{"id":1695,"date":"2026-08-20T17:17:59","date_gmt":"2026-08-20T21:17:59","guid":{"rendered":"https:\/\/opentextbooks.concordia.ca\/explorations3\/?post_type=chapter&#038;p=1695"},"modified":"2026-10-14T11:32:49","modified_gmt":"2026-10-14T15:32:49","slug":"human-variation-an-adaptive-significance-approach-test-wip","status":"publish","type":"chapter","link":"https:\/\/opentextbooks.concordia.ca\/explorations3\/chapter\/human-variation-an-adaptive-significance-approach-test-wip\/","title":{"raw":"Human Variation: An Adaptive Significance Approach","rendered":"Human Variation: An Adaptive Significance Approach"},"content":{"raw":"<div class=\"__UNKNOWN__\">\r\n<div class=\"textbox\">\r\n\r\nLearn more about <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/about-the-authors\/\">authors and editors<\/a>,<a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/student-contributors\/\"> Hess' student contributions<\/a>, and <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/versioning-history\/\">versioning history<\/a>.\r\n\r\n<\/div>\r\n\r\n<div class=\"textbox textbox--learning-objectives\"><header class=\"textbox__header\">\r\n<h2 class=\"textbox__title\">Learning Objectives<\/h2>\r\n<\/header>\r\n<div class=\"textbox__content\">\r\n<ul>\r\n \t<li class=\"import-Normal\" style=\"text-indent: 0pt\">Distinguish between adaptations and adjustments as ways of coping with environmental stressors.<\/li>\r\n \t<li class=\"import-Normal\" style=\"text-indent: 0pt\">Provide examples of adjustments humans use to cope with thermal stressors.<\/li>\r\n \t<li class=\"import-Normal\" style=\"text-indent: 0pt\">Describe how specific patterns of human adaptations and adjustments are correlated to natural selection processes.<\/li>\r\n \t<li class=\"import-Normal\" style=\"text-indent: 0pt\">Summarize the role of solar radiation in variations of human skin tone, and explain why reduced pigmentation is advantageous in northern latitudes.<\/li>\r\n \t<li class=\"import-Normal\" style=\"text-indent: 0pt\">Compare and contrast the various genetic mutations present in Tibetan and Ethiopian populations that allow them to survive at high altitudes.<\/li>\r\n \t<li class=\"import-Normal\" style=\"text-indent: 0pt\">Define the relationship between specific genetic mutations in some human populations and certain infectious diseases, such as the sickle-cell trait mutation and malarial infection.<\/li>\r\n<\/ul>\r\n<\/div>\r\n<\/div>\r\nAs early humans left Africa and spread across the globe, they faced numerous challenges related to their new environments. Beyond genetically influenced changes in physiology as a result of evolution, humans have developed lifestyle strategies to cope with and even thrive in a wide range of habitats. The ways populations of humans met such challenges, coupled with their geographic separation throughout the majority of the last two hundred thousand years, have led to the many forms of adaptation in our species. This chapter focuses on the complexities of modern human variation through the lens of human evolutionary history.\r\n<h2 class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Stress and Homeostasis<\/h2>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">All organisms, including humans, must maintain a baseline of normal functions within their cells, tissues, and organs to survive. This constancy of internal functions is referred to as <strong>[pb_glossary id=\"1840\"]homeostasis[\/pb_glossary].<\/strong> Homeostatic regulation, however, may be disrupted by a variety of both external and internal stimuli known as [pb_glossary id=\"1841\"]<strong>stressors<\/strong>.[\/pb_glossary] Within limits, all organisms have evolved certain physiological mechanisms to respond to stressors in an effort to maintain homeostasis. The range of changes in the physiology (function), morphology (form), and\/or behaviour of organisms in response to their environments and potential stressors is regulated by its [pb_glossary id=\"1842\"]<strong>phenotypic<\/strong><strong> plasticity<\/strong>[\/pb_glossary]. Coping with these stressors led to the development of both [pb_glossary id=\"1843\"]<strong>adjustments<\/strong>[\/pb_glossary] (behavioural, acclimatory, and developmental) and [pb_glossary id=\"1844\"]<strong>adaptations<\/strong>[\/pb_glossary], which are explained in detail in the following sections.<\/p>\r\n\r\n<h2 class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Adjustments and Adaptations<\/h2>\r\n<h3 class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Adjustments<\/strong><\/h3>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The term <em>adjustment<\/em> refers to an organism\u2019s nongenetic way of coping with the stressors of its environment. Although adjustments themselves are nongenetic in nature, the ability of an organism to experience or develop an adjustment is based on its phenotypic plasticity, which is linked to its evolutionarily guided genetic potential. Adjustments occur exclusively on the individual level. As such, different individuals within a population may experience a wide range of possible adjustments in response to a similar stressor. In general, the three main forms of adjustment are: behavioural, acclimatory, and developmental.<\/p>\r\n\r\n<h4 class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><em>Behavioural Adjustments<\/em><\/h4>\r\n[caption id=\"\" align=\"alignleft\" width=\"390\"]<img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2023\/06\/image3-3.jpg\" alt=\"Underwater photograph of scuba diver exploring the ocean floor.\" width=\"390\" height=\"293\" \/> Figure 15.1: Notice the lack of full-spectrum colour in this photo of a deep-water diver as well as the diver\u2019s use of specialized equipment, such as a breathing apparatus to deliver gasses for respiration, a bodysuit to ensure thermal regulation, and a flashlight to increase visibility in the low-light setting. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-13\/\" target=\"_blank\">Deep water diver<\/a> by Leslie E. Fitzpatrick is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.[\/caption]\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">When you are cold, do you reach for a blanket? When you are warm, do you seek out shelter cooled by an air-conditioning system? If so, you have likely been influenced to do so by the culture in which you were raised. As noted earlier in this textbook, the term <em>culture<\/em> refers to a collection of shared, learned beliefs and behaviours among individuals within a discrete population. <strong>[pb_glossary id=\"1845\"]Behavioural adjustments[\/pb_glossary]<\/strong> are regarded as cultural responses to environmental stressors. These adjustments are temporary in nature and, since they are nongenetic, must be constantly altered to meet novel situations posed by the environment. For example, divers are able to reach extraordinary depths (in excess of 300 metres below the surface) within the water through the use of a specialized mixture of gasses for breathing, an apparatus for the delivery of the gasses, protective clothing, and gear to increase visibility. The deeper a diver descends, the more atmospheric pressure the diver experiences, resulting in increased levels of potentially toxic byproducts of respiration within the body. In addition, with increased depth there is a decrease in the ambient temperature of the water and a decrease in the availability of light within the visible spectrum. Deep-water divers are well-versed in the environmental stressors of open waters and employ a variety of strategies based on behavioural adjustments to meet such demands. From wearing protective clothing to help maintain the body\u2019s core temperature to waiting at a specific depth for a prescribed period of time to facilitate the expulsion of nitrogen gas that may have accumulated within the bloodstream, divers employ numerous behavioural adjustments to ensure their safety (Figure 15.1). Without these culturally mediated behavioural adjustments, a deep-water diver\u2019s first dive would also be their last.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">In many developing countries, the use of refrigeration for the storage of perishable food products is uncommon; therefore, individuals within these cultures have developed a variety of behavioural adjustment strategies related to food preparation to address possible food spoilage. Through a cross-cultural analysis of spice use in recipes, Paul Sherman and Jennifer Billing (1999) determined that cultures closest to the equator, where temperatures are hotter, tend to use both a greater number and a wider variety of plant-based spices with bacteria-inhibiting phytochemical properties (e.g., garlic and onion). Antimicrobial properties of spices permits the consumption of foods, particularly animal-based protein sources, for a period of time beyond that which would be considered safe. There are some acclimatory adjustment benefits to the use of some pungent spices as well, which are explored in the following section.<\/p>\r\n\r\n<h4 class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><em>Acclimatory Adjustments: Thermal Stressors<\/em><\/h4>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>[pb_glossary id=\"1846\"]Acclimatory adjustments[\/pb_glossary]<\/strong> are temporary, reversible changes in an organism\u2019s physiology in response to environmental stressors. Although they are not genetically determined, the range of acclimatory adjustments that an organism is capable of producing is linked to its underlying phenotypic plasticity and the duration and severity of the stressor. A good example of this is the human response to varying ambient temperatures.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">To understand human adjustments, we must first understand the thermodynamic mechanisms through which heat may be gained or lost. The four pathways for this are conduction, convection, evaporation, and radiation (Figure 15.2).<\/p>\r\n\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"376\"]<img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image11-5.png\" alt=\"Person facing wall with arrows illustrating evaporation, conduction, radiation, and convection.\" width=\"376\" height=\"426\" \/> Figure 15.2: Various thermodynamic mechanisms related to heat gain and loss in the human body. This process is decribed in the text below. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-13\/\" target=\"_blank\">Mechanisms of heat transfer (Figure 14.2)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.[\/caption]\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Through <strong>[pb_glossary id=\"1847\"]conduction[\/pb_glossary]<\/strong> processes, heat will move from a warmer body to a cooler one through direct contact. An example of this is when you accidentally touch a hot cooktop with your hand and the heat is transferred from the cooktop to your skin.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">With [pb_glossary id=\"1848\"]<strong>convection<\/strong>[\/pb_glossary], when a warm body is surrounded by a cooler fluid (e.g., air or water), heat will be transferred from the warmer body to the cooler fluid. This is why we will often employ the behavioural adjustment of wearing multiple layers of clothing during the winter in an effort to prevent heat loss to the cooler atmosphere. Conversely, if your body temperature is cooler than that of the air surrounding you, your body will absorb heat.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Depending on your physical condition, most people will begin to sweat around 37.2\u2103 to 37.7\u2103 (98.9\u2109\u201399.9\u2109). Sweating is an example of [pb_glossary id=\"1849\"]<strong>evaporation<\/strong>[\/pb_glossary], which occurs when a liquid, such as the water within our bodies, is converted to a gas. Phase conversions, such as those underlying the evaporative processes of transforming liquids to gasses, require energy. In evaporation, this energy is in the form of heat, and the effect is to cool the body.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The final mechanism for heat loss within the human body is [pb_glossary id=\"1850\"]<strong>radiation<\/strong>[\/pb_glossary], through which energy in the form of electromagnetic waves is produced at a wavelength that typically lies below that which is visible to the human eye. Although humans gain and lose heat from their bodies through radiation, this form of heat transfer is not visible. Humans are capable of losing and gaining heat through conduction, convection, and radiation; however, heat may not be gained through evaporation.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">As the ambient temperature decreases, it becomes increasingly difficult for the human body to regulate its core temperature, which is central to the maintenance of homeostasis. When an individual\u2019s body temperature falls below 34.4\u2103 (93.9\u00b0F), the brain\u2019s <strong>[pb_glossary id=\"1851\"]hypothalamus[\/pb_glossary]<\/strong> becomes impaired, leading to issues with body temperature control. A total loss of the ability to regulate body temperature occurs around 29.4\u2103 (84.9\u00b0F), which may result in death. When the ambient temperature falls below the critical temperature of 31\u2103 (87.8\u00b0F), a nude human body that is at rest will respond with a series of physiological changes to preserve homeostasis (Figure 15.3).<\/p>\r\n\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"585\"]<img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image26-2.jpg\" alt=\"Body outlines illustrate differences in heat maintenance for different ambient environments.\" width=\"585\" height=\"347\" \/> Figure 15.3: Example of overall body heat maintenance in cold and warm ambient environments. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\">A full text description of this image is available<\/a>. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-13\/\" target=\"_blank\">Body heat maintenance in cold and warm (Figure 14.3)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.[\/caption]\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The human body experiences two main types of physiological responses to colder temperatures: those that increase the production of heat and those that seek to retain heat. The production of heat within the body is accomplished through short-term increases in the body\u2019s basal metabolic rate, such as shivering to increase muscular metabolism. An organism\u2019s basic metabolic rate is a measure of the energy required to maintain necessary body processes when the organism is at rest. Increases in basal metabolic rates, such as when we shiver from the cold, require increased consumption of energy-providing nutrients. Of course, such increases in metabolic rates are not infinite, as we may only consume a finite amount of nutrients. As with all <strong>[pb_glossary id=\"1846\"]acclimatory adjustments[\/pb_glossary]<\/strong>, an increase in the basal metabolic rate is merely temporary.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Of the physiological mechanisms to preserve heat already in the body, the most notable is [pb_glossary id=\"1853\"]<strong>vasoconstriction<\/strong>[\/pb_glossary], or the constriction of peripheral capillaries in the skin. The decreased surface area of the capillaries through vasoconstriction results in less heat reaching the surface of the skin where it would be dissipated into the atmosphere. Vasoconstriction also leads to the maintenance of heat near the core of the body where the vital organs are located. As a trade-off, though, individuals are more at risk of cold-related injuries, such as frost-bite, which can lead to tissue necrosis (tissue death) in regions of the body that are most distant from the core (e.g., fingers, toes, nose, ears, cheeks, chin, etc.).<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Just as cold stress presents challenges to maintaining homeostasis, heat does as well. In hot climates, the body will absorb heat from its surroundings (through conduction, convection, and radiation), resulting in potential heat-related disorders, such as heat exhaustion. When the human body is exposed to ambient temperatures above 35\u2103 (95\u00b0F), excess body heat will be lost primarily through evaporative processes, specifically through sweating. All humans, regardless of their environment, have approximately the same number of sweat glands within their bodies. Over time, individuals living in hot, arid environments will develop more sensitive forms of sweat glands resulting in the production of greater quantities of sweat (Best, Lieberman, and Kamilar 2019; Pontzer Et al. 2021). In an effort to prevent dehydration due to this form of acclimatory adjustment, there will be an additional reduction in the volume of urine produced by the individual (Pontzer Et al. 2021).<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">As noted in the previous section, some cultural groups, particularly those in equatorial regions, add pungent spices to their foods to inhibit the colonization of bacteria (Sherman and Billing 1999). Although adding spices to decrease spoilage rates is a behavioural adjustment, the application of some forms of peppers triggers an acclimatory adjustment as well. Compounds referred to as capsaicinoids are the secondary byproducts of chili pepper plants\u2019 metabolism and are produced to deter their consumption by some forms of fungi and mammals. When mammals, such as humans, consume the capsaicinoids from chili peppers, a burning sensation may occur within their mouths and along their digestive tracts. This burning sensation is the result of the activation of capsaicin receptors along the body\u2019s nerve pathways. Although the peppers themselves may be at ambient temperature so their consumption is not causing any form of body temperature increase, the human body perceives the pepper as elevating its core temperature due to the activation of the capsaicin receptors. This causes the hypothalamus to react, initiating sweating in an attempt to lower body temperature and maintain homeostasis. The increased piquancy (application of pungent spices to food) as a means of inhibiting food-borne bacterial colonization in warm climates, as well as spices\u2019 ability to trigger sweating processes as a method for cooling the body, is an example of the intersection between behavioural and acclimatory adjustments that utilized within certain populations.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">In addition to increased sweat production to maintain homeostasis in excess heat, <strong>[pb_glossary id=\"1854\"]vasodilation[\/pb_glossary]<\/strong> may occur (Figure 15.4). Vasodilation is an expansion of the capillaries within the skin leading to a more effective transfer of heat from within the body to the exterior to allow conductive, convective, radiative, and evaporative (sweating) processes to occur.<\/p>\r\n\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"499\"]<img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image27-4.png\" alt=\"Side-by-side sketches of capillaries under the skin for heat and cold.\" width=\"499\" height=\"445\" \/> Figure 15.4: The vasoconstriction processes occur within the peripheral vascular system when an individual is exposed to cold ambient temperatures and the vasodilation that occurs in warmer environments. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\">A full text description of this image is available<\/a>. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-13\/\" target=\"_blank\">Vasoconstriction and vasodilation (Figure 14.4)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.[\/caption]\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Physiologically based acclimatory adjustments to hot, dry climates may be complemented by behavioural adjustments as well. For example, individuals in such climates may limit their physical activity during the times of day when the temperature is typically the hottest. Additionally, these individuals may wear loose-fitting clothing that covers much of their skin. The looseness of the clothing allows for air to flow between the clothing and the skin to permit the effective evaporation of sweat. Although it may seem counterintuitive to cover one\u2019s body completely in a hot climate, the covering of the skin keeps the sun\u2019s rays from directly penetrating the skin and elevating the body\u2019s core temperature.<\/p>\r\n\r\n<h4 class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><em>Acclimatory Adjustments: Altitudinal Stressors<\/em><\/h4>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The challenges posed by thermal conditions are but one form of environmental stressor humans must face. High-altitude environments, which are defined as altitudes in excess of 2,400 metres above sea level (masl) or 7,874 feet above sea level (fasl), pose additional challenges to the maintenance of homeostasis in humans. Some of the main stressors encountered by those living within high-altitude environments include decreased oxygen availability, cold temperatures, low humidity, high wind speed, a reduced nutritional base, and increased solar radiation levels. Of these challenges, the most significant is the decreased availability of oxygen.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">To visualize how altitude affects the availability of oxygen, imagine two balloons that are each filled with the same quantity of oxygen molecules. One of these balloons is positioned at sea-level and the other is placed high upon a mountain peak. For the balloon at sea level, there is more atmospheric pressure pressing down on the molecules within this balloon. This leads to the oxygen molecules within the sea level balloon being forced into a more compact organization. In contrast, the mountain peak balloon has less atmospheric pressure pressing down on it. This leads to the oxygen molecules within that balloon spreading out from each other since they are not being forced together quite as strongly. This example highlights the availability of oxygen molecules in each breath than we take in low- versus high-altitude environments. At 5,500 masl (approximately 18,000 fasl), the atmospheric pressure is approximately 50% of its value at sea level (Peacock 1998). At the peak of Mount Everest (8,900 masl or approximately 29,200 fasl), the atmospheric pressure is equivalent to only about 30% of their sea level amounts (Peacock 1998; Figure 15.5).<\/p>\r\n\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"482\"]<img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image21-5.png\" alt=\"Atmospheric pressure decreases in density as a person climbs a mountain and increases in altitude. \" width=\"482\" height=\"418\" \/> Figure 15.5: As altitude increases, atmospheric pressure decreases, which allows for more space between air molecules. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-13\/\" target=\"_blank\">Atmospheric pressure (Figure 14.5)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.[\/caption]\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Due to decreased availability of oxygen at higher altitudes, certain acclimatory adjustments are required to ensure the maintenance of homeostasis for individuals other than those who were gestated, born, and raised at high altitude. For these people, their rate of breathing will increase to permit greater quantities of air containing oxygen into the lungs when they ascend into higher altitude environments. An increased speed and depth of breathing, which is referred to as [pb_glossary id=\"1855\"]<strong>hyperpnea<\/strong>[\/pb_glossary], is not sustainable indefinitely; thus, the rate of breathing begins to decrease as the person becomes acclimatized to the altitude. During the initial phases of high-altitude-related hyperpnea, the heart begins to beat faster but the amount of blood pushed through during each beat decreases slightly. In addition, the body will divert energy from noncritical bodily functions, such as digestive processes.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Once the atmospheric oxygen reaches the alveoli (small air sacs) in the lungs, it spreads across the alveolar membrane and enters <strong>[pb_glossary id=\"1858\"]erythrocytes[\/pb_glossary]<\/strong> (red blood cells). As oxygen reaches the alevoli\u2019s erythrocytes, it loosely binds with hemoglobin (an iron-rich protein) contained in the erythrocytes. When the erythrocytes carrying the hemoglobin-bound oxygen molecules reach capillaries where the partial pressure of oxygen is relatively low, oxygen will be released by the hemoglobin so that it is free for diffusion into body cells. Similar to acclimatory adjustments related to thermal conditions (e.g., shivering or sweating), those related to high altitude may not be infinitely sustained due to their energetically expensive nature.<\/p>\r\n\r\n\r\n[caption id=\"\" align=\"alignright\" width=\"430\"]<img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image24-3.jpg\" alt=\"Newborn lays face down on hospital bedding. Photograph is blue indicating UV light.\" width=\"430\" height=\"323\" \/> Figure 15.6: Premature infant born at 30 weeks, 4 days gestation to a mother with altitudinal-induced preeclampsia. Blue light assists the infant\u2019s liver with processing high levels of bilirubin. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-13\/\" target=\"_blank\">Premature infant<\/a> by Leslie E. Fitzpatrick is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.[\/caption]\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Although the long-term acclimatory adjustments that an individual from low altitude experiences in a high-altitude environment may permit them to reside there successfully, reproduction within such settings is frequently complicated. With increased altitude comes an increased risk of miscarriage, lower birth weights, and higher infant mortality rates. As the pregnant person\u2019s body seeks to preserve its own homeostasis, there is often a decreased rate and volume of blood flow to the uterus as compared to a pregnant person of similar physiological condition at a lower altitude (Moore, Niermeyer, and Zamudio 1998). This results in a decrease in the amount of oxygen that will be passed through the uterus and placenta to the developing fetus. In addition, pregnant people who experience pregnancy at higher altitudes are more prone to developing preeclampsia (severe elevation of blood pressure), which is linked to increased rates of both fetal and maternal death (Moore, Niermeyer, and Zamudio 1998; Figure 15.6).<\/p>\r\n\r\n<h4 class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><em>Developmental Adjustments <\/em><\/h4>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Developmental adjustments occur only in individuals who spent their developmental period (i.e., childhood and adolescence) within a high-altitude environment; they do not apply to those who moved into these environments in the post developmental (i.e., adult) phase. Furthermore, the degree of developmental adjustment within an individual is directly related to their underlying phenotypic plasticity as well as the amount of time during the crucial growth and development period that the individual resides within the challenging environment. Although humans have the remarkable capacity to develop and survive within environments that are not overly conducive to the successful maintenance of homeostasis, there are definitely physiological costs associated with this ability.<\/p>\r\n\r\n\r\n[caption id=\"\" align=\"alignleft\" width=\"369\"]<img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image18-2.jpg\" alt=\"Two people walking down a street wearing brightly colored woven traditional clothing.\" width=\"369\" height=\"277\" \/> Figure 15.7: Two individuals from a high-altitude region of the Peruvian Andes. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Andahuaylas_Peru-_two_women_walking_down_street.jpg\" target=\"_blank\">Andahuaylas Peru-two women walking down street<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:ThayneT\" target=\"_blank\">Thayne Tuason<\/a> has been modified (cropped) and is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/deed.en\" target=\"_blank\">CC BY 4.0 License<\/a>.[\/caption]\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">In general, high-altitude natives tend to grow more slowly and physically mature later than their low-altitude counterparts (Figure 15.7). Lowered growth and maturity rates are linked not only to the increased physiological demands placed on the body due to the decreased partial pressure of oxygen but also to reductions in the quality of the nutritional base at higher altitudes. Increased terrain complexity, elevated solar radiation levels, and higher wind speeds coupled with the lower temperatures and humidity levels found at high altitudes leads to difficulties with growing and maintaining crops and raising livestock. Overall, as altitude rises, the quality of the available nutritional base goes down, which is correlated to a lack of the nutrients necessary to ensure proper physiological growth and development in humans. Thus, even though individuals may be able to develop and grow within high-altitude environments, they may not reach their full genetically mediated growth potential as they would in a lower-altitude environment.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Not all developmental adjustments are linked to environmental pressures such as climate or altitude; rather, some of these adjustments are correlated to sociocultural or behavioural practices. Some of these adjustments may affect the physiological appearance of an individual when they are practiced consistently during the development and growth phases.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Sudden infant death syndrome (SIDS) has no definitive cause; however, the American Academy of Pediatrics published a report in 1992 linking SIDS to infants (under the age of one) sleeping on their stomachs. The \u201cBack to Sleep\u201d campaign championed by the American Academy of Pediatrics helped educate members of the medical community as well as the public that the best sleep position for infants is on their backs (American Academy of Pediatrics 2000).<\/p>\r\n\r\n\r\n\r\n[caption id=\"attachment_420\" align=\"aligncenter\" width=\"562\"]<img class=\"wp-image-419\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/14.8.jpg\" alt=\"Brachycephaly drawings show a flattened, symmetrical head. Plagiocephaly shows asymmetrical flattening of the skull.\" width=\"562\" height=\"219\" \/> Figure 15.8: These sketches illustrate a top and side view of brachycephaly (left and middle images, respectively) and plagiocephaly (right image). Credit: Brachycephaly and plagiocephaly original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Mary Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.[\/caption]\r\n\r\n<div class=\"__UNKNOWN__\">\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Placing infants on their backs to sleep has led to decreased infant mortality (death) rates due to SIDS; however, it has led to an unintended consequence: infant cranial deformation. The cranial deformations experienced by infants who sleep solely on their back tend to manifest in one of two forms: brachycephaly and plagiocephaly (Roby Et al. 2012; Figure 15.8). With positional brachycephaly, the back of the infant\u2019s head appears rather uniformly flattened due to repetitive contact with a flat surface, such as a crib mattress or car seat back. In cases of positional plagiocephaly, the back of the infant\u2019s head appears asymmetrically flattened. This asymmetry is typically due to an uneven distribution of mechanical forces resulting from the manner in which the infant\u2019s head is in contact with a flat surface. The forms of cranial deformation resulting from sleep positioning do not affect the infant\u2019s brain development. For many individuals, the appearance of the deformation is minimized during later development. Still, some individuals will maintain the pattern of cranial deformation acquired during their infancy throughout their lives. The unintentional cranial deformation resulting from placing infants on their backs to sleep as a means of preventing SIDS-related deaths is a physiological indicator of a behavioural adjustment.<\/p>\r\n\r\n<\/div>\r\n<h3 class=\"__UNKNOWN__\"><strong>Adaptations<\/strong><\/h3>\r\n<div class=\"__UNKNOWN__\">\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">As we have just explored, survival and reproduction at high altitudes present numerous physiological challenges for most humans. The behavioural, acclimatory, and developmental adjustments discussed above are all related to the phenotypic plasticity of the individual; however, most adjustments are temporary in nature and they affect a single individual rather than all individuals within a population. But what if the physiological changes were permanent? What if they affected all members of a population rather than just a single individual? The long-term, microevolutionary (i.e., genetic) changes that occur within a population in response to an environmental stressor are referred to as an adaptation. From an evolutionary standpoint, the term <em>adaptation<\/em> refers to a phenotypic trait (i.e., physiological\/morphological feature or behaviour) that has been acted upon by natural selection processes to increase a species\u2019 ability to survive and reproduce within a specific environment. Within the field of physiology, the term <em>adaptation<\/em> refers to traits that serve to restore homeostasis. The physiology-based interpretation of adaptations presumes that all traits serve a purpose and that all adaptations are beneficial in nature; however, this may be a fallacy, since some traits may be present without clear evidence as to their purpose. As such, during the following discussion of various forms of adaptations in human populations, we will focus our attention on phenotypic traits with an evidence-based purpose.<\/p>\r\n\r\n<h4 class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><em>Adaptation: <\/em><em>Altitudinal Adaptation<\/em><\/h4>\r\n<\/div>\r\n\r\n[caption id=\"attachment_420\" align=\"aligncenter\" width=\"619\"]<img class=\"wp-image-420\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/14.9.jpg\" alt=\"The Simian Plateau in northeast Africa and Tibetan Plateau in southern Asia.\" width=\"619\" height=\"339\" \/> Figure 15.9: Highlighted regions feature (from left to right) the Simian (Ethiopian) and Tibetan Plateau high-altitude regions. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:World_Map_of_HVR_adaptation_in_high_altitude_populations.jpg\" target=\"_blank\">World Map of HVR adaptation in high altitude populations<\/a> by Chkuu has been modified (cropped, Andean region colour change) and is under <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\" target=\"_blank\">CC BY-SA 4.0 License<\/a>.[\/caption]\r\n\r\n<div class=\"__UNKNOWN__\">\r\n\r\nAs mentioned in the previous section, there is genomic research supporting the evolutionary selection of certain phenotypes and their corresponding genotypes within indigenous high-altitude populations across the globe. The following discussion focuses on two high-altitude indigenous populations from Tibet and Ethiopia (Figure 15.9). Although these populations share many common genetic traits based on relatively similar evolutionary histories influenced by similar environmental stressors, there is support for local genetically based adaptation as well, based on different genes being acted upon by environmental stressors that may be unique to Tibet and Ethiopia (Bigham 2016).\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Tibetan populations have resided in the Tibetan Plateau and Himalayan Mountain regions at elevations exceeding 4,000 masl (13,100 fasl) for at least the past 7,400 years (Meyer Et al. 2017). There is evidence of a genetic exchange event involving Tibetan populations and Denisovans around 48,700 years ago, which introduced a haplogroup involving mutations of the <em>EPAS1<\/em> gene (Zhang Et al. 2021). The <em>EPAS1<\/em> is involved in the regulation of erythrocytes and hemoglobin. For individuals originating in lower-altitude environments, <em>EPAS1 <\/em>stimulates increased erythrocyte production in high-altitude environments as a temporary acclimatory adjustment. For indigenous high-altitude populations of Tibet, the <em>EPAS1<\/em> gene mutation introduced by Denisovan introgression inhibits increased erythrocyte production, which reduces potential negative effects (e.g., stroke or heart attack) associated with long-term high levels of erythrocyte production (Gray Et al. 2022; Zhang Et al. 2021). The erythrocyte count of high-altitude Tibetans with the <em>EPAS1<\/em> point mutation is about the same as for individuals residing at sea level.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Populations indigenous to the Semien Plateau of Ethiopia, such as the Oromo and Amhara, share a similar but not identical <em>EPAS1<\/em> point mutation with the Tibetan population (Bigham 2016); however, there is no indication that this mutation was derived from Denisovan introgression. The <em>EPAS1<\/em> mutations occurred independently from each other; however, their effects are still similar in that they permit the Tibetan and Ethiopian populations to survive at high altitudes. Not all adaptations are related to life in high-altitude environments, however. In the following sections, we will address two more general examples of adaptation in human populations: variations in skin colour and differences in body build.<\/p>\r\n\r\n<h4 class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><em>Adaptation: Skin Tone<\/em><em> Basics<\/em><\/h4>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">When you think about your own skin tone and compare it to members of your family, do you all possess exactly the same shade? Are some members of your family darker than others? What about your friends? Your classmates? Skin tone occurs along a continuum, which is a reflection of the complex evolutionary history of our species. The expression of skin tone is regulated primarily by melanin and hemoglobin. <strong>[pb_glossary id=\"1871\"]Melanin[\/pb_glossary]<\/strong> is a dark brown-black pigment that is produced by the oxidation of certain amino acids (e.g., tyrosine, cysteine, phenylalanine) in melanocytes. <strong>[pb_glossary id=\"1872\"]Melanocytes[\/pb_glossary]<\/strong> are specialized cells located in the base layer (stratum basale) of the skin\u2019s epidermis as well as several other areas within the body (Figure 15.10). Within the melanocytes, melanin is produced in the special organelle called a melanosome. Melanosomes serve as sites for the synthesis, storage, and transportation of melanin. Melanosomes transport the melanin particles through cellular projections to epidermal skin cells (keratinocytes) as well as to the base of the growing hair root. In the eye, however, melanin particles produced by the melanosomes remain present within the iris and are not transported beyond their origin location. The two main forms of melanin related to skin, hair, and eye colour are eumelanin and pheomelanin. All humans contain both eumelanin and pheomelanin within their bodies; however, the relative expression of these two forms of melanin determines an individual\u2019s overall colouring. Eumelanin is a brown-to-black coloured melanin particle while pheomelanin is more pink-to-red coloured. Individuals with darker skin or hair colour have a greater expression of eumelanin than those with lighter-coloured skin and blonde or red hair.<\/p>\r\n\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"553\"]<img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image12-2.jpg\" alt=\"Melanocytes and melanosomes are compared from light and dark skin tones.\" width=\"553\" height=\"436\" \/> Figure 15.10: Diagram featuring the relative numbers of melanocytes and melanosomes in light and dark shades of skin tone. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\">A full text description of this image is available<\/a>. Credit: <a href=\"https:\/\/openstax.org\/books\/anatomy-and-physiology-2e\/pages\/5-1-layers-of-the-skin#fig-ch05_01_07\" target=\"_blank\">Skin Pigmentation (Anatomy and Physiology, Figure 5.8)<\/a> by <a href=\"https:\/\/openstax.org\/\" target=\"_blank\">OpenStax<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\" target=\"_blank\">CC BY 4.0 License<\/a>.[\/caption]\r\n<h4 class=\"import-Normal\"><em>Adaptation<\/em><em>: <\/em><em>Melanogenesis <\/em><\/h4>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Although all humans have approximately the same number of melanocytes within their epidermis, the production of melanin by these melanocytes varies. There are two forms of melanogenesis (the process through which melanocytes generate melanin): basal and activated. As discussed previously, the expression of eumelanin and pheomelanin by the melanocytes is genetically regulated through the expression of specific receptors (e.g., <em>MC1R<\/em>) or other melanocyte components (e.g., <em>MFSD12<\/em>)<em>.<\/em> <strong>[pb_glossary id=\"1873\"]Basal melanogenesis[\/pb_glossary] <\/strong>is dependent upon an individual\u2019s inherent genetic composition and is not influenced by external factors. [pb_glossary id=\"1874\"]<strong>Activated melanogenesis<\/strong>[\/pb_glossary] occurs in response to ultraviolet radiation (UV) exposure, specifically UV-B (short UV wave) exposure. Increased melanogenesis in response to UV-B exposure serves to provide protection to the skin\u2019s innermost layer called the hypodermis, which lies below the epidermis and dermis (Figure 15.11). Melanin in the skin, specifically eumelanin, effectively absorbs UV-B radiation from light\u2014meaning that it will not reach the hypodermal layer. This effect is often more apparent during periods of the year when people tend to be outside more and the weather is warmer, which leads to most donning fewer protective garments. The exposure of skin to sunlight is, of course, culturally mediated with some cultures encouraging the covering of skin at all times.<\/p>\r\n\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"395\"]<img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image10-6.png\" alt=\"Cross-section of skin illustrating UVA rays penetrate deeper than UVB. \" width=\"395\" height=\"407\" \/> Figure 15.11: Penetration of skin layers by UVA and UVB rays. UVB rays penetrate only through the epidermis. UVA rays penetrate much deeper, through the dermis. Credit: <a href=\"https:\/\/cnx.org\/contents\/FPtK1zmh@16.7:RxywCGkA@10\/5-1-Layers-of-the-Skin\" target=\"_blank\">Skin Pigmentation (Anatomy and Physiology, Figure 5.8)<\/a> by<a href=\"https:\/\/openstax.org\/\" target=\"_blank\"> OpenStax<\/a> is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\" target=\"_blank\"> CC BY 4.0 License<\/a>.[\/caption]\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">As previously noted in this chapter, hemoglobin is an iron-rich protein that binds with oxygen in the bloodstream. For individuals with lighter-coloured skin, blood vessels near the surface of the skin and the hemoglobin contained within those vessels is more apparent than in individuals with darker skin. The visible presence of hemoglobin coupled with the pink-to-red tone of the pheomelanin leads to lighter-skinned individuals having a pale pink skin tone. Individuals with lighter skin more readily absorb UV radiation as their basal melanin expression is directed more toward the production of pheomelanin than eumelanin. But why are there so many variations in skin tone in humans? To answer this question, we now turn toward an exploration of an evolutionary-based adaptation of skin tone as a function of the environment.<\/p>\r\n\r\n<h4 class=\"import-Normal\"><em>Adaptation: <\/em><em>Evolutionary Basis for Skin Tone Variation<\/em><\/h4>\r\n[caption id=\"\" align=\"alignleft\" width=\"337\"]<img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image22-4.png\" alt=\"Table discussing hair and skin, folate and UV rays, leaving Africa, vitamin D, and selective pressures.\" width=\"337\" height=\"843\" \/> Figure 15.12: Evolutionary basis for human skin colour variation. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\">A full text description of this image is available<\/a>. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-13\/\" target=\"_blank\">Evolutionary basis for human skin color variation (Figure 14.12)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Katie Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.[\/caption]\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Skin cancer is a significant concern for many individuals with light skin tone as the cumulative exposure of the epidermis and underlying skin tissues to UV radiation may result in the development of abnormal cells within those tissues, leading to malignancies. Although darker-skinned individuals are at risk for skin cancer as well, they are less likely to develop it due to increased levels of melanin, specifically eumelanin, in their skin. Even though skin cancer is a serious health concern for some individuals, most skin cancers occur in the postreproductive years; therefore, it is improbable that evolutionary forces favouring varying melanin expression levels are related to a selective pressure to avoid such cancers. Furthermore, if avoiding skin cancer were the primary factor driving the evolution of various skin tones, then it reasons that everyone would have the most significant expression of eumelanin possible. So, why do we have different skin tones (Figure 15.12)?<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The term <strong>[pb_glossary id=\"1875\"]cline[\/pb_glossary]<\/strong> (introduced in Chapter 14) refers to the continuum or spectrum of gradations (i.e., levels or degrees) from one extreme to another. With respect to skin tone, the various tonal shades occur clinally with darker skin being more prevalent near the equator and gradually decreasing in tone (i.e., decreased melanin production) in more distant latitudes. For individuals who are indigenous to equatorial regions, the increased levels of melanin within their skin provides them with a measure of protection against both sunburn and sunstroke because the melanin is more reflective of UV radiation than hemoglobin. In cases of severe sunburn, eccrine glands are affected, resulting in an individual\u2019s ability to sweat being compromised. As sweat is the body\u2019s most effective means of reducing its core temperature to maintain homeostasis, damage to the eccrine glands may lead to numerous physiological issues related to heat that may ultimately result in death.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Even though avoiding severe sunburn and sunstroke is of great importance to individuals within equatorial regions, this is likely not the primary factor driving the evolutionary selection of darker skin within these regions. It has been proposed that UV radiation\u2019s destruction of [pb_glossary id=\"1876\"]<strong>folic acid<\/strong>[\/pb_glossary], which is a form of B-complex vitamin, may have led to the selection of darker skin in equatorial regions. For pregnant people, low levels of folic acid within the body during gestation may lead to defects in the formation of the brain and spinal cord of the fetus. This condition, which is referred to as spina bifida (Figure 15.13), often significantly reduces an infant\u2019s chances of survival without medical intervention. In people producing sperm, low levels of folic acid within the body reduce sperm quantity and quality. Thus, in geographic regions with high UV radiation levels (i.e., equatorial regions), there appears to be an evolutionarily driven correlation between darker skin and fertility.<\/p>\r\n\r\n\r\n[caption id=\"\" align=\"alignright\" width=\"364\"]<img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image19-2-1.jpg\" alt=\"Infant with a bulging spinal cord above the lower spine.\" width=\"364\" height=\"294\" \/> Figure 15.13: Infant with open neural tube defect in lower (lumbar) region of the spine (right). A close-up of the open neural tube defect within the spinal column (left) shows the dura matter, which is ordinarily protected within the spine, is exposed on the surface of the skin. The spinal cord sits near the surface, when it should be protected within the spinal column. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Spina-bifida.jpg\" target=\"_blank\">Spina-bifida<\/a> by the <a href=\"https:\/\/www.cdc.gov\/\" target=\"_blank\">Centers for Disease Control and Prevention<\/a> is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\" target=\"_blank\">public domain<\/a>.[\/caption]\r\n\r\nIf darker skin tone is potentially correlated to more successful reproduction, then why do lighter shades of skin exist? One hypothesis is that there is a relationship between lighter skin tone and vitamin D synthesis within the body. When skin is exposed to the UV-B radiation waves in sunlight, a series of chemical reactions occur within the epidermis leading to the production of vitamin D3, which is a fat-soluble vitamin that assists the body with absorbing calcium and phosphorus in the small intestine. These nutrients are among those that are critical for the proper growth and maintenance of bone tissue within the body. In the absence of adequate minerals, particularly calcium, bone structure and strength will be compromised, leading to the development of rickets during the growth phase. Rickets is a disease affecting children during their growth phase. It is characterized by inadequately calcified bones that are softer and more flexible than normal. Individuals with rickets will develop a true bowing of their legs, which may affect their mobility (Figure 15.14). In addition, deformation of pelvic bones in people who may become pregnant may occur as a result of rickets, leading to complications with reproduction. In adults, a deficiency in vitamin D3 will often result in osteomalacia, which is a general softening of the bones due to inadequate mineralization. As noted, a variety of maladies may occur due to the inadequate production or absorption of vitamin D3, as well as the destruction of folate within the human body. Therefore, from an evolutionary perspective, natural selection should favour a skin tone that is best suited to a given environment.\r\n\r\n[caption id=\"\" align=\"alignleft\" width=\"263\"]<img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image9-2-1.jpg\" alt=\"Historic photo of three young children each with visible lower limb curvature.\" width=\"263\" height=\"315\" \/> Figure 15.14: Children with rickets in various developmental stages. Credit: <a href=\"https:\/\/wellcomecollection.org\/works\/m3eu5snb\" target=\"_blank\">Rachitis, stages of development for children<\/a> [slide numbers 7181 and 7182; photo number: M0003399] by <a href=\"https:\/\/wellcomecollection.org\/\" target=\"_blank\">Wellcome Collection<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\" target=\"_blank\">CC BY 4.0 License<\/a>.[\/caption]In general, the trend related to lighter skin pigmentation further from the equator follows a principle called [pb_glossary id=\"1877\"]<strong>Gloger\u2019s Rule<\/strong>[\/pb_glossary]. This rule states that within the same species of mammals the more heavily pigmented individuals tend to originate near the equator while lighter-pigmented members of the species will be found in regions further from the equator. Gloger\u2019s Rule applies latitudinally; however, it does not appear to hold for certain human populations near the poles. Specifically, it does not apply to the Inuit people (Figure 15.15), who are indigenous to regions near the North Pole and currently reside in portions of Canada, Greenland, Alaska, and Denmark. The Inuit have a darker skin tone that would not be anticipated under the provisions of Gloger\u2019s Rule. The high reflectivity of light off of snow and ice, which is common in polar regions, necessitates the darker skin tone of these individuals to prevent folic acid degradation just as it does for individuals within equatorial regions. The consumption of vitamin D\u2013rich foods, such as raw fish, permits the Inuit to reside at high latitudes with darker skin tone while preventing rickets.\r\n<h4 class=\"import-Normal\"><em>Adaptation: <\/em><em>Shape and Size Variations<\/em><\/h4>\r\n[caption id=\"\" align=\"alignright\" width=\"353\"]<img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image6-3-1.jpg\" alt=\"Historic photo of a person carrying a very large fish laid on a pack.\" width=\"353\" height=\"296\" \/> Figure 15.15: Copper Inuk (from Bernard Harbour, Nunavut) with lake trout on his back (1915). Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Copper_Inuk_with_lake_trout_on_his_back_near_Bernard_Harbour_(51007).jpg\" target=\"_blank\">Copper Inuk with lake trout on his back near Bernard Harbour, Northwest Territories (Nunavut)<\/a> (1915) by George H. Wilkins is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/deed.en\" target=\"_blank\">CC BY-SA 4.0 License<\/a>. This image is part of the Photographic Archives of the Canadian Museum of History.[\/caption]\r\n\r\nIn addition to natural selection playing a role in the determination of melanin expression, it plays a significant role in the determination of the shape and size of the human body. As previously discussed, the most significant thermodynamic mechanism of heat loss from the body is radiation. At temperatures below 20\u2103 (68\u2109), the human body loses around 65% of its heat to radiative processes; however, the efficiency of radiation is correlated to the overall body shape and size of the individual. There is a direct correlation between the ratio of an object\u2019s surface area to mass and the amount of heat that may be lost through radiation. For example, two objects of identical composition and mass are heated to the same temperature. One object is a cube and the other is a sphere. Which object will cool the fastest? Geometrically, a sphere has the smallest surface area per unit mass of any three-dimensional object, so the sphere will cool more slowly than the cube. In other words, the smaller the ratio of the surface area to mass an object has, the more it will retain heat. With respect to the cube in our example, mass increases by the cube, but surface area may increase only by the square, so size will affect the mass to surface area ratio. This, in general, holds true for humans, as well.\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">In regions where temperatures are consistently cold, the body shape and size of individuals indigenous to the area tend to be more compact. These individuals have a relatively higher body mass to surface area (i.e., skin) than their counterparts from equatorial regions where the average temperatures are considerably warmer. Individuals from hot climates, such as the Fulani (Figure 15.16) of West Africa, have limbs that are considerably longer than those of individuals from cold climates, such as the Inuit of Greenland (Figure 15.16). Evolutionarily, the longer limbs of individuals from equatorial regions (e.g., the Fulani) provide a greater surface area (i.e., lower body mass to surface area ratio) for the dissipation of heat through radiative processes. In contrast, the relatively short limbs of Arctic-dwelling people, such as the Inuit, allows for the retention of heat because there is a decreased surface area through which heat may radiate away from the body.<\/p>\r\n\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"385\"]<img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image20-2.jpg\" alt=\"Person on left is stocky, person on right has a narrow body breadth.\" width=\"385\" height=\"570\" \/> Figure 15.16: The individual on the left is typical of one adapted to a cold environment where the conservation of heat in the body\u2019s core is of critical importance.The individual on the right could be adapted to a tropical environment where the rapid dispersal of heat is necessary to maintain homeostasis. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Greenland_1999_(01).jpg\" target=\"_blank\">Greenland 1999 (01)<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Vadeve\" target=\"_blank\">Vadeve<\/a> has been designated to the <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/cc0\/\" target=\"_blank\">public domain (CC0)<\/a>.[\/caption]\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">As described above, there are certain trends related to the general shape and size of human bodies in relation to the thermal conditions. To better describe these trends, we turn to a couple of general principles that are applicable to a variety of species beyond humans. [pb_glossary id=\"1879\"]<strong>Bergmann\u2019s Rule<\/strong>[\/pb_glossary] predicts that as average environmental temperature decreases, populations are expected to exhibit an increase in weight and a decrease in surface area (Figure 15.17a). Also, within the same species of homeothermic animals, the relative length of projecting body parts (e.g., nose, ears, and limbs) increases in relation to the average environmental temperature (Figure 15.17b). This principle, referred to as [pb_glossary id=\"1880\"]<strong>Allen\u2019s Rule<\/strong>[\/pb_glossary], notes that longer, thinner limbs are advantageous for the radiation of excess heat in hot environments and shorter, stockier limbs assist with the preservation of body heat in cold climates. A measure of the crural index (crural index = tibia length <span style=\"font-size: NaNpt;color: #;text-decoration: none\">\u00f7 <\/span>femur length) of individuals from various human populations provides support for Allen\u2019s Rule since this value is lower in individuals from colder climates than it is for those from hot climates. The crural indices for human populations vary directly with temperature, so individuals with higher crural index values are generally from regions with a warmer average environmental temperature. Conversely, the crural indices are lower for individuals from regions where there are colder average temperatures.<\/p>\r\n\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"533\"]<img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image16-6.png\" alt=\"Illustration of an elk (left) and gazelle (right).\" width=\"533\" height=\"319\" \/> Figure 15.17a: These organisms are representative of Bergmann\u2019s rule. The animal on the left depicts an ungulate from a cooler environment with increased body weight and decreased surface area, compared to the slender ungulate on the right. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-13\/\" target=\"_blank\">Bergmann\u2019s Rule (Figure 14.16a)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.[\/caption]\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"521\"]<img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image14-4.png\" alt=\"Three types of rabbits with different ear and forelimb lengths.\" width=\"521\" height=\"264\" \/> Figure 15.17b: These animals are representative of Allen\u2019s rule. The rabbit on the left comes from a cooler environment and is compact with short limbs and ears. The rabbit on the right comes from a warm environment and has long and lanky limbs and ears. The rabbit in the middle has ears and limbs that are in-between the other two. Rabbits do not sweat like humans; heat is dissipated primarily through their ears. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-13\/\" target=\"_blank\">Allen\u2019s Rule (Figure 14.16b)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.[\/caption]\r\n\r\n[caption id=\"\" align=\"alignleft\" width=\"627\"]<img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image17-6.png\" alt=\"Four noses with varying heights, arches, and nostril breadth.\" width=\"627\" height=\"237\" \/> Figure 15.18: Human nasal morphological variation as influenced by four major climate-based adaptive zones: hot-dry, hot-wet, cold-dry, and cold-wet. The four noses in this figure vary in shape in relation to their respective climate-based adaptive zones. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-13\/\" target=\"_blank\">Human nasal morphological variation (Figure 14.17)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.[\/caption]\r\n\r\nNasal shape and size (Figure 15.18) is another physiological feature affected by our ancestors\u2019 environments. The selective role of climate in determining human nasal variation is typically approached by dividing climates into four adaptive zones: hot-dry, hot-wet, cold-dry, and cold-wet (Maddux Et al. 2016). A principal role of the nasal cavity is to condition (i.e., warm and humidify) ambient air prior to its reaching the lungs. Given this function of the nasal cavity, it is anticipated that different nasal shapes and sizes will be related to varying environments. In cold-dry climates, an individual\u2019s nasal cavity must provide humidification and warmth to the dry air when breathing in through the nose (Noback Et al. 2011). Also, in that type of climate, the nasal cavity must conserve moisture and minimize heat loss during when the individual exhales through the nose (Noback Et al. 2011). From a physiological stress perspective, this is a stressful event.\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Conversely, in hot-wet environments, there is no need for the nasal cavity to provide additional moisture to the inhaled air nor is there a need to warm the air or to preserve heat within the nasal cavity (Noback Et al. 2011). So, in hot-wet climates, the body is under less physiological stress related to the inhalation of ambient air than in cold-dry climates. As with most human morphological elements, the shape and size of the nasal cavity occurs along a cline. Due to the environmental stressors of cold-dry environments requiring the humidification and warming of air through the nasal cavity, individuals indigenous to such environments tend to have taller (longer) noses with a reduced nasal entrance (nostril opening) size (Noback Et al. 2011). This general shape is referred to as leptorrhine, and it allows for a larger surface area within the nasal cavity itself for the air to be warmed and humidified prior to entering the lungs (Maddux Et al. 2016). In addition, the relatively small nasal entrance of leptorrhine noses serves as a means of conserving moisture and heat (Noback Et al. 2011). Individuals indigenous to hot-wet climates tend to have platyrrhine nasal shapes, which are shorter with broader nasal entrances (Maddux Et al. 2016). Since individuals in hot-wet climates do not need to humidify and warm the air entering the nose, their nasal tract is shorter and the nasal entrance wider to permit the effective cooling of the nasal cavity during respiratory processes.<\/p>\r\n\r\n<h4 class=\"import-Normal\"><em>Adaptation: Infectious Disease<\/em><\/h4>\r\n<p class=\"import-Normal\">Throughout our evolutionary journey, humans have been exposed to numerous infectious diseases. In the following section, we will explore some of the evolutionary-based adaptations that have occurred in certain populations in response to the stressors presented by select infectious diseases. One of the primary examples of natural selection processes acting on the human genome in response to the presence of an infectious disease is the case of the relationship between the sickle-cell anemia trait and malaria, introduced in Chapter 5.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Malaria is a zoonotic disease (an infectious disease transmitted between animals and humans; it is covered in more detail in Chapter 17). It is caused by the spread of the parasitic protozoa from the genus <em>Plasmodium <\/em>(Figure 15.19). These unicellular, eukaryotic protozoa are transmitted through the bite of a female <em>Anopheles<\/em> mosquito. During the bite process, the protozoan parasites present within an infected mosquito\u2019s saliva enter a host\u2019s bloodstream where they are transported to the liver. Within the liver, the parasites multiply and are eventually released into the bloodstream, where they infect erythrocytes. Once inside the erythrocytes, the parasites reproduce until they exceed the cell\u2019s storage capacity, causing it to burst and release the parasites into the bloodstream once again. This replication cycle continues as long as there are viable erythrocytes within the host to infect.<\/p>\r\n\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"518\"]<img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image13-1-1.jpg\" alt=\"Life cycle stages of Malaria parasite.\" width=\"518\" height=\"511\" \/> Figure 15.19: Life cycle of the malaria parasite. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\">A full text description of this image is available<\/a>. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Malaria_parasite_life_cycle-NIAID.jpg\" target=\"_blank\">Malaria parasite life cycle-NIAID<\/a> by <a href=\"https:\/\/www.niaid.nih.gov\/\" target=\"_blank\">NIH National Institute of Allergy and Infectious Diseases<\/a> is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\" target=\"_blank\">public domain<\/a>.[\/caption]\r\n<p class=\"import-Normal\">General complications from malaria infections include the following: enlargement of the spleen (due to destruction of infected erythrocytes); lower number of thrombocytes (also called platelets, required for coagulation\/clotting of blood); high levels of bilirubin (a byproduct of hemoglobin breakdown in the liver) in the blood; jaundice (yellowing of the skin and eyes due to increased blood bilirubin levels); fever; vomiting; retinal (eye) damage; and convulsions (seizures). In 2020, there were 241 million cases of malaria reported globally, with 95% of those cases originating in Africa (World Health Organization 2021). In sub-Saharan Africa, where incidents of malaria are the highest in the world, 125 million pregnancies are affected by malaria, resulting in 200,000 infant deaths (Hartman, Rogerson, and Fischer 2013). Pregnant people who become infected during the gestational process are more likely to have low-birthweight infants due to prematurity or growth restriction inside the uterus (Hartman, Rogerson, and Fischer 2013). After birth, infants born to malaria-infected pregnant people are more likely to develop infantile anemia (low red-blood cell counts), a malaria infection that is not related to the maternal malarial infection, and they are more likely to die than infants born to non-malaria-infected pregnant people (Hartman, Rogerson, and Fischer 2013).<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">For children and adolescents whose brains are still developing, there is a risk of cognitive (intellectual) impairment associated with some forms of malaria infections (Fernando, Rodrigo, and Rajapakse 2010). Given the relatively high rates of morbidity (disease) and mortality (number of deaths) associated with malaria, it is plausible that this disease may have served as a selective pressure during human evolution. Support for natural selection related to malaria resistance is related to genetic mutations associated with sickle cell, thalassemia, glucose-6-phosphate dehydrogenase (G6PD) deficiency, and the absence of certain antigens (molecules capable of inducing an immune response from the host) on erythrocytes. For the purposes of this text, we will focus our discussion on the relationship between sickle cell disease and malaria.<\/p>\r\n\r\n\r\n[caption id=\"\" align=\"alignright\" width=\"312\"]<img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image15-2-1.jpg\" alt=\"Normal (round) and sickle (crescent-shaped) red blood cells flow through a blood vessel. \" width=\"312\" height=\"499\" \/> Figure 15.20: Normal and sickled erythrocytes. Normal red blood cells are round and can easily flow freely through blood vessels. Abnormal, or cicle, blood cells are half moon shaped and can easily become entangled and block blood flow. Sickle cells have abnormal hemoglobin that form strands that cause the sickle shape. The Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Sickle_cell_01.jpg\" target=\"_blank\">Sickle cell 01<\/a> by <a href=\"https:\/\/www.nhlbi.nih.gov\/health\/sickle-cell-disease\" target=\"_blank\">The National Heart, Lung, and Blood Institute (NHLBI)<\/a> is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\" target=\"_blank\">public domain<\/a>.[\/caption]\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>[pb_glossary id=\"1881\"]Sickle cell disease[\/pb_glossary]<\/strong> is a group of genetically inherited blood disorders characterized by an abnormality in the shape of the hemoglobin within erythrocytes. It is important to note that there are multiple variants of hemoglobin, including, but not limited to the following: A, D, C, E, F, H, S, Barts, Portland, Hope, Pisa, and Hopkins. Each of these variants of hemoglobin may result in various conditions within the body; however, for the following explanation we will focus solely on variants A and S.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Individuals who inherit a mutated gene (hemoglobin with a sickled erythrocyte variety, HbS) on chromosome 11 from both parents will develop sickle cell anemia, which is the most severe form of the sickle cell disease family (Figure 15.20). The genotype of an individual with sickle cell anemia is HbSS; whereas, an individual without sickle cell alleles has a genotype of HbAA representing two normal adult hemoglobin type A variants. Manifestations of sickle cell anemia (HbSS) range from mild to severe, with some of the more common symptoms being anemia, blood clots, organ failure, chest pain, fever, and low blood-oxygen levels. In high-income countries with advanced medical care, the median life expectancy of an HbSS individual is around 60 years; however, in low-income countries where advanced medical care is scarce, as many as 90% of children with sickle cell disease perish before the age of five (Longo Et al. 2017).<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Considering that advanced medical care was not available during much of human evolutionary history, it stands to reason that the majority of individuals with the HbSS genotype died before the age of reproduction. If that is the case though, why do we still have the HbS variant present in modern populations? As covered earlier in this textbook, the genotype of an individual is composed of genes from both biological parents. In the case of an individual with an HbSS genotype, the sickle cell allele (HbS) was inherited from each of the parents. For individuals with the heterozygous genotype of HbSA, they have inherited both a sickle cell allele (HbS) and a normal hemoglobin allele (HbA). Heterozygous (HbSA) individuals who reside in regions where malaria is endemic may have a selective advantage. They will experience a sickling of some, but not all, of their erythrocytes. As discussed in the following paragraph, HbSA heterozygous individuals are less likely to die from malaria infections than their HbAA counterparts. Unlike an individual with the HbSS genotype, someone with HbSA may experience some of the symptoms listed above; however, they are generally less severe.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">As noted earlier, the mechanism through which <em>Plasmodium<\/em> protozoan parasites replicate involves human erythrocyte cells. However, due to their sickled shape, as well as the presence of an abnormally shaped protein within the cell, the parasites are unable to replicate effectively in the erythrocyte cells coded for by the HbS allele (Cyrklaff Et al. 2011). An individual who has an HbSA genotype and an active malaria infection will become ill with the disease to a lesser extent than someone with an HbAA genotype, which increases their chances of survival. Although normal erythrocytes (regulated by the HbA allele) allow for parasite replication, they are not able to replicate in HbS erythrocytes of the heterozygote. So, individuals with the HbSA genotype are more likely to survive a malaria infection than an individual who is HbAA. Although individuals with the HbSA genotype may endure some physiological complications related to the sickling of some of their erythrocytes, their morbidity and mortality rates are lower than they are for HbSS members of the population. The majority of individuals who are heterozygous or homozygous for the HbS trait have ancestors who originated in sub-Saharan Africa, India, Saudi Arabia, and regions in South and Central America, the Mediterranean (Turkey, Greece, and Italy), and the Caribbean (Centers for Disease Control and Prevention 2017; Figure 15.21).<\/p>\r\n\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"511\"]<img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image23-3.png\" alt=\"Map illustrating distribution of sickle cell and associated erythrocytic abnormalities for Africa and Asia.\" width=\"511\" height=\"306\" \/> Figure 15.21: Distribution of sickle cell and associated erythrocytic abnormalities for Africa and Asia. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Red_Blood_Cell_abnormalities.png\" target=\"_blank\">Red Blood Cell abnormalities<\/a> by Armando Moreno Vranich has been designated to the <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/cc0\/\" target=\"_blank\">public domain (CC0)<\/a>.[\/caption]\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">With respect to the history of these regions, during the early phases of settlement horticulture was the primary method of crop cultivation. Typically performed on a small scale, horticulture is based on manual labour and relatively simple hand tools rather than the use of draft animals or irrigation technologies. Common in horticulture is <em>swidden<\/em>, or the cutting and burning of plants in woodland and grassland regions. The swidden is the prepared field that results following a slash-and-burn episode. This practice fundamentally alters the soil chemistry, removes plants that provide shade, and increases the areas where water may pool. This anthropogenically altered landscape provides the perfect breeding ground for the <em>Anopheles<\/em> mosquito, as it prefers warm, stagnant pools of water (Figure 15.22).<\/p>\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"561\"]<img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image5-6.png\" alt=\"Horticulture encourages mosquitos, increasing malaria. Balancing selection maintains normal and sickle cell alleles.\" width=\"561\" height=\"468\" \/> Figure 15.22: The effects of human horticultural activities on the balancing selection of populations in relation to sickle cell disease genotype variants. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\">A full text description of this image is available<\/a>. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-13\/\" target=\"_blank\">Sickle cell disease (Figure 14.21)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Katie Nelson is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>. [Includes two horticulture illustrations by Mary Nelson, <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Sickle_cell_anemia.jpg\" target=\"_blank\">Sickle cell anemia<\/a> by <a href=\"https:\/\/en.wikibooks.org\/wiki\/User:Pkleong\" target=\"_blank\">Pkleong<\/a> at <a href=\"https:\/\/en.wikibooks.org\/wiki\/\" target=\"_blank\">English Wikibooks<\/a> (modified), <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/cc0\/\" target=\"_blank\">public domain (CC0)<\/a>.][\/caption]\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Although swidden agriculture was historically practiced across the globe, it became most problematic in the regions where the <em>Anopheles<\/em> mosquito is endemic. These areas have the highest incidence rates of malaria infection. Over time, the presence of the <em>Anopheles<\/em> mosquito and the <em>Plasmodium<\/em> parasite that it transmitted acted as a selective pressure, particularly in regions where swidden agricultural practices were common, toward the selection of individuals with some modicum of resistance against the infection. In these regions, HbSS and HbSA individuals would have been more likely to survive and reproduce successfully. Although individuals and populations are far more mobile now than they have been throughout much of history, there are still regions where we can see higher rates of malaria infection as well as greater numbers of individuals with the HbS erythrocyte variant. The relationship between malaria and the selective pressure for the HbS variant is one of the most prominent examples of natural selection in the human species within recent evolutionary history.<\/p>\r\n\r\n<h4 class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><em>Adaptation: Lactase Persistence <\/em><\/h4>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">With the case of sickled erythrocytes and their resistance to infection by malaria parasites, there is strong support for a cause-and-effect-style relationship linked to natural selection. Although somewhat less apparent, there is a correlation between lactase persistence and environmental challenges. Lactase-phlorizin hydrolase (LPH) is an enzyme that is primarily produced in the small intestine and permits the proper digestion of lactose, a disaccharide (composed of two simple sugars: glucose and galactose) found in the milk of mammals. Most humans will experience a decrease in the expression of LPH following weaning, leading to an inability to properly digest lactose. Generally, LPH production decreases between the ages of two and five and is completely absent by the age of nine (Dzialanski Et al. 2016). For these individuals, the ingestion of lactose may lead to a wide variety of gastrointestinal ailments, including abdominal bloating, increased gas, and diarrhea. Although the bloating and gas are unpleasant, the diarrhea caused by a failure to properly digest lactose can be life-threatening if severe enough due to the dehydration it can cause. Some humans, however, are able to produce LPH far beyond the weaning period.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Individuals who continue to produce LPH have what is referred to as the <strong>[pb_glossary id=\"1882\"]lactase persistence[\/pb_glossary] <\/strong>trait. The lactase persistence trait is encoded for a gene called <em>LCT<\/em>, which is located on human chromosome 2 (Ranciaro Et al. 2014). From an evolutionary and historical perspective, this trait is most commonly linked to cultures that have practiced cattle domestication (Figure 15.23). For individuals in those cultures, the continued expression of LPH may have provided a selective advantage. During periods of environmental stress, such as a drought, if an individual is capable of successfully digesting cow\u2019s milk, they have a higher chance of survival than someone who suffers from diarrhea-linked dehydration due to a lack of LPH. Although the frequency of the lactase persistence trait is relatively low among African agriculturalists, it is high among pastoralist populations that are traditionally associated with cattle domestication, such as the Tutsi and Fulani, who have frequencies of 90% and 50%, respectively (Tishkoff Et al. 2007).<\/p>\r\n\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"632\"]<img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image4-4.png\" alt=\"Map depicting the percentage of adults with lactase persistence in the eastern hemisphere.\" width=\"632\" height=\"497\" \/> Figure 15.23: Interpolated map depicting the percentage of adults with the lactase persistence genotype in indigenous populations of Africa, Europe, Asia, and Australia. Circles denote sample locations. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Lactose_tolerance_in_the_Old_World.svg\" target=\"_blank\">Lactose tolerance in the Old World<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Joe_Roe\" target=\"_blank\">Joe Roe<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/legalcode\" target=\"_blank\">CC BY 4.0 License<\/a>.[\/caption]\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Cattle domestication began around 11,000 years ago in Europe (Beja-Pereira Et al. 2006) and 7,500 to 9,000 years ago in the Middle East and North Africa (Tishkoff Et al. 2007). Based on human genomic studies, it is estimated that the mutation for the lactase persistence trait occurred around 2,000 to 20,000 years ago for European populations (Tishkoff Et al. 2007). For African populations, the lactase persistence trait emerged approximately 1,200 to 23,000 years ago (Gerbault Et al. 2011). This begs the question: Is this mutation the same for both populations? It appears that the emergence of the lactase persistence mutation in non-European populations, specifically those in East Africa (e.g., Tutsi and Fulani), is a case of <strong>convergent evolution<\/strong>. With convergent evolution events, a similar mutation may occur in species of different lineages through independent evolutionary processes. Based on our current understanding of the genetic mutation pathways for the lactase persistence trait in European and African populations, these mutations are not representative of a shared lineage. In other words, just because a person of European origin and a person of African origin can each digest milk due to the presence of the lactase-persistence trait in their genotypes, it does not mean that these two individuals inherited it due to shared common ancestry.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Is it possible that the convergent evolution of similar lactase-persistence traits in disparate populations is merely a product of genetic drift? Or is there evidence for natural selection? Even though 23,000 years may seem like a long time, it is but a blink of the proverbial evolutionary eye. From the perspective of human evolutionary pathways, mutations related to the <em>LCT<\/em> gene have occurred relatively recently. Similar genetic changes in multiple populations through genetic drift processes, which are relatively slow and directionless, fail to accumulate as rapidly as lactase-persistence traits (Gerbault Et al. 2011). The widespread accumulation of these traits in a relatively short period of time supports the notion that an underlying selective pressure must be driving this form of human evolution. Although to date no definitive factors have been firmly identified, it is thought that environmental pressures are likely to credit for the rapid accumulation of the lactase-persistence trait in multiple human populations through convergent evolutionary pathways.<\/p>\r\n\r\n<div class=\"textbox\">\r\n<h2 class=\"import-Normal\">Special Topic: Skin Tone Genetic Regulation<\/h2>\r\n<p class=\"import-Normal\">The melanocortin 1 receptor (<em>MC1R<\/em>) gene acts to control which types of melanin (eumelanin or pheomelanin) are produced by melanocytes. The <em>MC1R<\/em> receptor is located on the surface of the melanocyte cells (Quillen Et al. 2018). Activation of the <em>MC1R <\/em>receptors may occur through exposure to specific environmental stimuli or due to underlying genetic processes. Inactive or blocked <em>MC1R <\/em>receptors result in melanocytes producing pheomelanin. If the <em>MC1R<\/em> gene receptors are activated, then the melanocytes will produce eumelanin. Thus, individuals with activated <em>MC1R<\/em> receptors tend to have darker-pigmented skin and hair than individuals with inactive or blocked receptors.<\/p>\r\n<p class=\"import-Normal\">The alleles of another gene, the major facilitator, superfamily domain-containing protein 12 (<em>MFSD12<\/em>) gene, affect the expression of melanocytes in a different way than the <em>MC1R<\/em> gene. Instead of affecting the activation of melanocyte receptors, the <em>MFSD12<\/em> alleles indirectly affect the membranes of melanocyte lysosomes (Quillen Et al. 2018). The melanocyte\u2019s lysosomes are organelles containing digestive enzymes, which ultimately correlate to varying degrees of pigmentation in humans. Variations in the membranes of the melanocyte lysosomes ultimately correlate to differing degrees of pigmentation in humans.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Ancestral <em>MFSD12 <\/em>allele variants are present in European and East Asian populations and are associated with lighter pigmentation of the skin (Crawford Et al. 2017; Quillen Et al. 2018). In addition, this ancestral variant is also associated with Tanzanian, San, and Ethiopian populations of Afro-Asiatic ancestry (Crawford Et al. 2017; Quillen Et al. 2018). In contrast, the more derived (i.e., more recent) allele variants that are linked to darker skin tones are more commonly present in East African populations, particularly those of Nilo-Saharan descent (Crawford Et al. 2017; Quillen Et al. 2018). The notion that ancestral alleles of <em>MFSD12<\/em> are associated with lighter skin pigmentation is in opposition to the commonly accepted idea that our pigmentation was likely darker throughout early human evolution (Crawford Et al. 2017; Quillen Et al. 2018). Due to the complexity of the human genome, <em>MFSD12<\/em> and <em>MC1R <\/em>are but two examples of alleles affecting human skin tone. Furthermore, there is genetic evidence suggesting that certain genomic variants associated with both darker and lighter skin colour have been subject to directional selection processes for as long as 600,000 years, which far exceeds the evolutionary span of <em>Homo sapiens sapiens<\/em> (Crawford Et al. 2017; Quillen Et al. 2018).<\/p>\r\n\r\n<\/div>\r\n<\/div>\r\n<div class=\"__UNKNOWN__\">\r\n<div class=\"textbox shaded\">\r\n<h2>Summary<\/h2>\r\nFrom the time that the first of our species left Africa, we have had to adjust and adapt to numerous environmental challenges. The remarkable ability of human beings to maintain homeostasis through a combination of both nongenetic (adjustments) and genetic (adaptations) means has allowed us to occupy a remarkable variety of environments, from high-altitude mountainous regions to the tropics near the equator. From adding piquant, pungent spices to our foods as a means of inhibiting food-borne illnesses due to bacterial growth to donning garments specially suited to local climates, behavioural adjustments have provided us with a nongenetic means of coping with obstacles to our health and well-being. Acclimatory adjustments, such as sweating when we are warm in an attempt to regulate our body temperature or experiencing increased breathing rates as a means of increasing blood oxygen levels in regions where the partial pressure of oxygen is low, have been instrumental in our survival with respect to thermal and altitudinal environmental challenges. For some individuals, developmental adjustments that were acquired during their development and growth phases (e.g., increased heart and lung capacities for individuals from high-altitude regions) provide them with a form of physiological advantage not possible for someone who ventures to such an environmentally challenging region as an adult. Genetically mediated adaptations, such as variations in the pigmentation of our skin, have ensured our evolutionary fitness across all latitudes. Taken together, these examples point to a broader question: will the human species continue to adjust and adapt to new environmental challenges in the future? If past performance is any measure of future expectations, then the human story will continue as long as we do not alter our environment to the point that the plasticity of our behaviour, physiological, and morphological boundaries is exceeded.\r\n<h2 class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Review Questions<\/h2>\r\n<ul>\r\n \t<li class=\"import-Normal\" style=\"text-indent: 0pt\">Detail at least two examples of how natural selection has influenced human variation. Specifically, what was the selective pressure that may have led to a preference for a specific trait and how is that trait related to an increased level of fitness?<\/li>\r\n \t<li class=\"import-Normal\" style=\"text-indent: 0pt\">Why is reduced pigmentation of the skin advantageous for individuals from northern latitudes? What role does darker skin pigmentation serve for individuals near the equator? What is the relationship between skin pigmentation and fitness?<\/li>\r\n \t<li class=\"import-Normal\" style=\"text-indent: 0pt\">What are some of the risks associated with pregnancy at high altitude? Compare and contrast the various genetic mutations of the indigenous Tibetan and Ethiopian high-altitude populations. In your answer, specifically address the issue of pregnancy at high altitudes.<\/li>\r\n \t<li class=\"import-Normal\" style=\"text-indent: 0pt\">What is the relationship between the sickle cell mutation and the <em>Plasmodium<\/em> parasite? Would having the HbSA genotype still be advantageous in a region where such parasites are not common? Why or why not?<\/li>\r\n<\/ul>\r\n<\/div>\r\n&nbsp;\r\n<h2 class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Key Terms<strong>\r\n<\/strong><\/h2>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Acclimatory adjustm<\/strong><strong>ents<\/strong>: Processes by which an individual organism adjusts in order to maintain homeostasis in response to environmental challenges.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Activated melanogenesis<\/strong>: Increase in melanin production in response to ultraviolet radiation (UV) exposure.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Adaptation<\/strong>: Alteration in population-level gene frequencies related to environmentally induced selective pressures; leads to a greater level of fitness for a population related to a specific environment.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Adjustment<\/strong>: Nongenetic-based ways in which organisms adjust to environmental stressors.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Allen\u2019s Rule<\/strong>: Due to thermal adaptation, homeothermic animals have body volume-to-surface ratios that vary inversely with the average temperature of their environment. In cold climates, the anticipated ratio is high; in warm climates, it is low.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Basal melanogenesis<\/strong>: Genetically mediated, non-environmentally influenced base melanin level.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Behavioural adjustments<\/strong>: An individual\u2019s culturally mediated responses to an environmental stressor in an effort to maintain homeostasis.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Bergmann\u2019s Rule<\/strong>: For a broadly distributed monophyletic group, species and populations of smaller size tend to be found in environments with warmer climates and those of larger size tend to be found in ones that are colder.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Cline<\/strong>: A continuum of gradations (i.e., degrees or levels) of a specific trait.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Conduction<\/strong>: Mechanism of heat transfer between objects through direct contact.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Convection<\/strong>: Movement of heat away from a warm object to the cooler surrounding fluid (i.e., gas or liquid).<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Convergent evolution<\/strong>: Evolutionary process whereby organisms that are not closely related independently evolve similar traits as a product of adaptation to similar evolutionary parameters.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Erythrocyte<\/strong>: Red blood cell; most common form of blood cell; the principle means of transporting oxygen throughout the circulatory system.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Evaporation<\/strong>: Mechanism of heat transfer whereby liquid is transformed into a gas, utilizing energy (e.g., heat).<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Folic acid<\/strong>: Form of B complex vitamin necessary for proper fetal development.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Gloger\u2019s Rule<\/strong>: For mammals of the same species, those with more darkly pigmented forms tend to be found closer to the equator and those with lighter forms are found in regions further from the equator.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Homeostasis<\/strong>: Condition of optimal functioning for an organism.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Hyperpnea<\/strong>: Increased depth and rate of respiration.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Hypothalamus<\/strong>: Small portion of the human brain responsible for body temperature regulation.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Lactase persistence<\/strong>: Genetic mutation permitting the continued production of lactase-phlorizin hydrolase enzyme in the small intestine past the weaning period.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Melanin<\/strong>: Black-brown pigment produced by melanocytes; one of the primary pigments in skin.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Melanocytes<\/strong>: Specialized cells that produce melanin.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Phenotypic plasticity<\/strong>: Ability of one genotype to produce more than one phenotype dependent on environmental conditions.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Radiation<\/strong>: Mechanism of heat transfer involving electromagnetic energy being emitted from an object.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Sickle cell disease<\/strong>: A group of genetically inherited blood disorders characterized by an abnormality in the shape of the hemoglobin within erythrocytes (red blood cells).<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Stressor<\/strong>: Any stimulus resulting in an imbalance in an organism\u2019s homeostatic balance.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Vasoconstriction<\/strong>: Narrowing of the blood vessels due to contractions of the muscular vessel walls.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Vasodilation<\/strong>: Dilation of the blood vessels due to relaxation of the muscular vessel walls.<\/p>\r\n\r\n<h2 class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">For Further Exploration<strong>\r\n<\/strong><\/h2>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Homeostasis<\/strong><\/p>\r\n<p class=\"import-Normal\">Baptista, Vander. 2006. \u201c<a href=\"https:\/\/doi.org\/10.1152\/advan.00075.2006\" target=\"_blank\" rel=\"noopener\">Starting Physiology: Understanding Homeostasis<\/a>.\u201d <em>Advances in Physiology Education<\/em> 30: 263\u2013264.<\/p>\r\n<p class=\"import-Normal\">Goldstein, David S., and Bruce McEwen. 2002. \u201c<a href=\"https:\/\/doi.org\/10.1080\/102538902900012345\" target=\"_blank\" rel=\"noopener\">Allostasis, Homeostats, and the Nature of Stress<\/a>.\u201d <em>The International Journal on the Biology of Stress<\/em> 5 (1): 55\u201358.<\/p>\r\n<p class=\"import-Normal\"><strong>General Clinal Variation and Genetic Exchange<\/strong><\/p>\r\n<p class=\"import-Normal\">Delhey, Kaspar. 2019. \u201c<a href=\"https:\/\/doi.org\/10.1111\/brv.12503\" target=\"_blank\" rel=\"noopener\">A Review of Gloger's Rule, an Ecogeographical Rule of Colour: Definitions, Interpretations and Evidence<\/a>.\u201d <em>Biological Reviews<\/em> 94 (4): 1294\u20131316.<\/p>\r\n<p class=\"import-Normal\">Feng, Yuanqing, Michael A. McQuillan, and Sarah A. Tishkoff. 2021. \u201c<a href=\"https:\/\/doi.org\/10.1093\/hmg\/ddab007\" target=\"_blank\" rel=\"noopener\">Evolutionary Genetics of Skin Pigmentation in African Populations<\/a>.\u201d <em>Human Molecular Genetics<\/em> 30 (R1): R88\u2013R97.<\/p>\r\n<p class=\"import-Normal\">Hu, Hao, Nayia Petousi, Gustavo Glusman, Yao Yu, Ryan Bohlender, Tsewang Tashi, Jonathan M. Downie, et al. 2017. \u201c<a href=\"https:\/\/doi.org\/10.1371\/journal.pgen.1006675\" target=\"_blank\" rel=\"noopener\">Evolutionary History of Tibetans Inferred from Whole-Genome Sequencing<\/a>.\u201d <em>PLoS Genetics <\/em>13 (4): e1006675. .<\/p>\r\n<p class=\"import-Normal\">Jablonski, Nina G. 2021. \u201c<a href=\"https:\/\/doi.org\/10.1002\/ajpa.24200\" target=\"_blank\" rel=\"noopener\">Skin Color and Race<\/a>.\u201d Special issue, \u201cRace Reconciled II: Interpreting and Communicating Biological Variation and Race in 2021,\u201d <em>American Journal of Physical Anthropology<\/em> 175 (2): 437\u2013447.<\/p>\r\n<p class=\"import-Normal\">Pritchard, Jonathan K., Joseph K. Pickrell, and Graham Coop. 2010. \u201c<a href=\"https:\/\/doi.org\/10.1016\/j.cub.2009.11.055\" target=\"_blank\" rel=\"noopener\">The Genetics of Human Adaptation: Hard Sweeps, Soft Sweeps, and Polygenic Adaptation<\/a>.\u201d <em>Current Biology<\/em> 20 (4): R208\u2013R215.<\/p>\r\n<p class=\"import-Normal\">Sankararaman, Sriram, Swapan Mallick, Nick Patterson, and David Reich. 2016. \u201c<a href=\"https:\/\/doi.org\/10.1016\/j.cub.2016.03.037\" target=\"_blank\" rel=\"noopener\">The Combined Landscape of Denisovan and Neanderthal Ancestry in Present-Day Humans<\/a>.\u201d <em>Current Biology<\/em> 26 (9): 1241\u20131247.<\/p>\r\n<p class=\"import-Normal\"><strong>Lactase Persistence<\/strong><\/p>\r\n<p class=\"import-Normal\">HHMI BioInteractive. 2021. \u201c<a href=\"https:\/\/www.biointeractive.org\/classroom-resources\/making-fittest-got-lactase-co-evolution-genes-and-culture\" target=\"_blank\" rel=\"noopener\">The Making of the Fittest: Got Lactase? The Co-evolution of Genes and Culture<\/a>.\u201d Accessed April 7, 2023.<\/p>\r\n<p class=\"import-Normal\"><strong>Malaria and Sickle Cell Anemia<\/strong><\/p>\r\n<p class=\"import-Normal\">Bill and Melinda Gates Foundation. 2022. \u201c<a href=\"https:\/\/www.gatesfoundation.org\/our-work\/programs\/global-health\/malaria\" target=\"_blank\" rel=\"noopener\">Malaria<\/a>.\u201d Accessed April 7, 2023.<\/p>\r\n<p class=\"import-Normal\">Centers for Disease Control and Prevention. 2022. \u201c<a href=\"https:\/\/www.cdc.gov\/parasites\/malaria\/index.html\" target=\"_blank\" rel=\"noopener\">Malaria<\/a>.\u201d Accessed April 7, 2023.<\/p>\r\n<p class=\"import-Normal\">HHMI BioInteractive. 2020. \u201c<a href=\"https:\/\/www.biointeractive.org\/classroom-resources\/making-fittest-natural-selection-humans\" target=\"_blank\" rel=\"noopener\">The Making of the Fittest: Natural Selection in Humans<\/a>.\u201d 2020. Accessed April 7, 2023.<\/p>\r\n<p class=\"import-Normal\">National Institutes of Health: National Center for Advancing Translational Sciences. \u201c<a href=\"https:\/\/rarediseases.info.nih.gov\/diseases\/8614\/sickle-cell-anemia\" target=\"_blank\" rel=\"noopener\">Sickle Cell Anemia<\/a>.\u201d Accessed April 7, 2023.<\/p>\r\n<p class=\"import-Normal\">World Health Organization. 2022. \u201c<a href=\"https:\/\/www.who.int\/news-room\/fact-sheets\/detail\/malaria\" target=\"_blank\" rel=\"noopener\">Malaria<\/a>.\u201d Accessed April 7, 2023.<\/p>\r\n<p class=\"import-Normal\"><strong>Rickets and Bone Health<\/strong><\/p>\r\n<p class=\"import-Normal\">National Institutes of Health: National Center for Advancing Translational Sciences. \u201c<a href=\"https:\/\/rarediseases.info.nih.gov\/diseases\/5700\/rickets\" target=\"_blank\" rel=\"noopener\">Rickets<\/a>.\u201d Accessed April 7, 2023.<\/p>\r\n<p class=\"import-Normal\">Talmadge, D. W., and R. V. Talmadge. 2007. \u201cCalcium Homeostasis: How Bone Solubility Relates to All Aspects of Bone Physiology.\u201d <em>Journal of Musculoskeletal and Neuronal Interactions <\/em>7 (2): 108\u2013112.<\/p>\r\n<p class=\"import-Normal\"><strong>Skin Colour<\/strong><\/p>\r\n<p class=\"import-Normal\">HHMI BioInteractive. 2020. \u201c<a href=\"https:\/\/www.biointeractive.org\/classroom-resources\/biology-skin-color\" target=\"_blank\" rel=\"noopener\">The Biology of Skin Color<\/a>.\u201d Accessed April 7, 2023<\/p>\r\n\r\n<h2 class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">References<\/h2>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">American Academy of Pediatrics, Task Force on Infant Sleep Position and Sudden Infant Death Syndrome. 2000. \u201cChanging Concepts of Sudden Infant Death Syndrome: Implications for Infant Sleeping Environment and Sleep Position.\u201d <em>Pediatrics<\/em> 105 (3): 650\u2013656.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Beja-Pereira, Albano, David Caramelli, Carles Lalueza-Fox, Cristiano Vernesi, Nuno Ferrand, Antonella Casoli, Felix Goyache, et al. 2006. \u201cThe Origin of European Cattle: Evidence from Modern and Ancient DNA.\u201d <em>PNAS <\/em>103 (21): 8113\u20138118.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Best, Andre, Daniel E. 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J. 1998. \u201cABC of Oxygen: Oxygen at High Altitude.\u201d <em>BMJ<\/em> 317 (7165): 1063\u20131066.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Pontzer, Herman, Mary H. Brown, Brian M. Wood, David A. Raichlen, Audax Z.P. Madbulla, Jacob A. Harris, Holly Dunsworth, et al. 2021. \u201cEvolution of Water Conservation in Humans.\u201d <em>Current Biology<\/em> 31 (8): 1804\u20131810.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Quillen, Ellen E., Heather L. Norton, Esteban J. Parra, Frida Loza-Durazo, Khai C. Ang, Florin Mircea Illiescu, Laurel N. Pearson, et al. 2019. \u201cShades of Complexity: New Perspectives on the Evolution and Genetic Architecture of Human Skin.\u201d <em>Yearbook<\/em><em> of Physical Anthropology <\/em>168 (S67): 4\u201326.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Ranciaro, Alessia, Michael C. Campbell, Jibril B. Hirbo, Wen-Ya Ko, Alain Froment,<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Paolo Anagnostou, Maritha J. Kotze, et al. 2014. \u201cGenetic Origins of Lactase Persistence and the Spread of Pastoralism in Africa.\u201d <em>American Journal of Human Genetics <\/em>94 (4): 496\u2013510.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Roby, Brianne Barnett, Marsha Finkelstein, Robert J. Tibesar, and James D. Sidman. 2012. \u201cPrevalence of Positional Plagiocephaly in Teens Born after the \u2018Back to Sleep\u2019 Campaign.\u201d <em>Otolaryn<\/em><em>g<\/em><em>ology<\/em><em>\u2014Head and Neck Surgery<\/em> 146 (5): 823\u2013828.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Sherman, Paul W., and Jennifer Billing. 1999. \u201cDarwinian Gastronomy: Why We Use Spices.\u201d <em>BioScience <\/em>49 (6): 453\u2013463.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Tishkoff, Sarah A., Floyd A. Reed, Alessia Ranciaro, Benjamin F. Voight, Courtney C. Babbitt, Jesse S. Silverman, Kweli Powell, et al. 2007. \u201cConvergent Adaptation of Human Lactase Persistence in Africa and Europe.\u201d <em>Nature Genetics<\/em> 39 (1): 31\u201340.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">World Health Organization. 2021. \u201c<a href=\"https:\/\/www.who.int\/teams\/global-malaria-programme\/reports\/world-malaria-report-2021\" target=\"_blank\" rel=\"noopener\">World Malaria Report 2021<\/a>.\u201d <em>World Health Organization<\/em> website, December 4, 2022. Accessed April 7, 2023.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Zhang, Xinjun, Kelsey E. Witt, Mayra M. Ba\u00f1uelos, Amy Ko, Kai Yuan, Shuhua Xu, Rasmus Nielsen, and Emilia Huerta-Sanchez. 2021. \u201cThe History and Evolution of Denisovan-<em>EPAS1<\/em> Haplotype in Tibetans.\u201d <em>PNAS Biological Sciences<\/em> 118 (22): 1\u20139.<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><\/p>\r\n\r\n<\/div>\r\n<\/div>","rendered":"<div class=\"__UNKNOWN__\">\n<div class=\"textbox\">\n<p>Learn more about <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/about-the-authors\/\">authors and editors<\/a>,<a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/student-contributors\/\"> Hess&#8217; student contributions<\/a>, and <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/versioning-history\/\">versioning history<\/a>.<\/p>\n<\/div>\n<div class=\"textbox textbox--learning-objectives\">\n<header class=\"textbox__header\">\n<h2 class=\"textbox__title\">Learning Objectives<\/h2>\n<\/header>\n<div class=\"textbox__content\">\n<ul>\n<li class=\"import-Normal\" style=\"text-indent: 0pt\">Distinguish between adaptations and adjustments as ways of coping with environmental stressors.<\/li>\n<li class=\"import-Normal\" style=\"text-indent: 0pt\">Provide examples of adjustments humans use to cope with thermal stressors.<\/li>\n<li class=\"import-Normal\" style=\"text-indent: 0pt\">Describe how specific patterns of human adaptations and adjustments are correlated to natural selection processes.<\/li>\n<li class=\"import-Normal\" style=\"text-indent: 0pt\">Summarize the role of solar radiation in variations of human skin tone, and explain why reduced pigmentation is advantageous in northern latitudes.<\/li>\n<li class=\"import-Normal\" style=\"text-indent: 0pt\">Compare and contrast the various genetic mutations present in Tibetan and Ethiopian populations that allow them to survive at high altitudes.<\/li>\n<li class=\"import-Normal\" style=\"text-indent: 0pt\">Define the relationship between specific genetic mutations in some human populations and certain infectious diseases, such as the sickle-cell trait mutation and malarial infection.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<p>As early humans left Africa and spread across the globe, they faced numerous challenges related to their new environments. Beyond genetically influenced changes in physiology as a result of evolution, humans have developed lifestyle strategies to cope with and even thrive in a wide range of habitats. The ways populations of humans met such challenges, coupled with their geographic separation throughout the majority of the last two hundred thousand years, have led to the many forms of adaptation in our species. This chapter focuses on the complexities of modern human variation through the lens of human evolutionary history.<\/p>\n<h2 class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Stress and Homeostasis<\/h2>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">All organisms, including humans, must maintain a baseline of normal functions within their cells, tissues, and organs to survive. This constancy of internal functions is referred to as <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1840\">homeostasis<\/a>.<\/strong> Homeostatic regulation, however, may be disrupted by a variety of both external and internal stimuli known as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1841\"><strong>stressors<\/strong>.<\/a> Within limits, all organisms have evolved certain physiological mechanisms to respond to stressors in an effort to maintain homeostasis. The range of changes in the physiology (function), morphology (form), and\/or behaviour of organisms in response to their environments and potential stressors is regulated by its <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1842\"><strong>phenotypic<\/strong><strong> plasticity<\/strong><\/a>. Coping with these stressors led to the development of both <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1843\"><strong>adjustments<\/strong><\/a> (behavioural, acclimatory, and developmental) and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1844\"><strong>adaptations<\/strong><\/a>, which are explained in detail in the following sections.<\/p>\n<h2 class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Adjustments and Adaptations<\/h2>\n<h3 class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Adjustments<\/strong><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The term <em>adjustment<\/em> refers to an organism\u2019s nongenetic way of coping with the stressors of its environment. Although adjustments themselves are nongenetic in nature, the ability of an organism to experience or develop an adjustment is based on its phenotypic plasticity, which is linked to its evolutionarily guided genetic potential. Adjustments occur exclusively on the individual level. As such, different individuals within a population may experience a wide range of possible adjustments in response to a similar stressor. In general, the three main forms of adjustment are: behavioural, acclimatory, and developmental.<\/p>\n<h4 class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><em>Behavioural Adjustments<\/em><\/h4>\n<figure style=\"width: 390px\" class=\"wp-caption alignleft\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2023\/06\/image3-3.jpg\" alt=\"Underwater photograph of scuba diver exploring the ocean floor.\" width=\"390\" height=\"293\" \/><figcaption class=\"wp-caption-text\">Figure 15.1: Notice the lack of full-spectrum colour in this photo of a deep-water diver as well as the diver\u2019s use of specialized equipment, such as a breathing apparatus to deliver gasses for respiration, a bodysuit to ensure thermal regulation, and a flashlight to increase visibility in the low-light setting. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-13\/\" target=\"_blank\">Deep water diver<\/a> by Leslie E. Fitzpatrick is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">When you are cold, do you reach for a blanket? When you are warm, do you seek out shelter cooled by an air-conditioning system? If so, you have likely been influenced to do so by the culture in which you were raised. As noted earlier in this textbook, the term <em>culture<\/em> refers to a collection of shared, learned beliefs and behaviours among individuals within a discrete population. <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1845\">Behavioural adjustments<\/a><\/strong> are regarded as cultural responses to environmental stressors. These adjustments are temporary in nature and, since they are nongenetic, must be constantly altered to meet novel situations posed by the environment. For example, divers are able to reach extraordinary depths (in excess of 300 metres below the surface) within the water through the use of a specialized mixture of gasses for breathing, an apparatus for the delivery of the gasses, protective clothing, and gear to increase visibility. The deeper a diver descends, the more atmospheric pressure the diver experiences, resulting in increased levels of potentially toxic byproducts of respiration within the body. In addition, with increased depth there is a decrease in the ambient temperature of the water and a decrease in the availability of light within the visible spectrum. Deep-water divers are well-versed in the environmental stressors of open waters and employ a variety of strategies based on behavioural adjustments to meet such demands. From wearing protective clothing to help maintain the body\u2019s core temperature to waiting at a specific depth for a prescribed period of time to facilitate the expulsion of nitrogen gas that may have accumulated within the bloodstream, divers employ numerous behavioural adjustments to ensure their safety (Figure 15.1). Without these culturally mediated behavioural adjustments, a deep-water diver\u2019s first dive would also be their last.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">In many developing countries, the use of refrigeration for the storage of perishable food products is uncommon; therefore, individuals within these cultures have developed a variety of behavioural adjustment strategies related to food preparation to address possible food spoilage. Through a cross-cultural analysis of spice use in recipes, Paul Sherman and Jennifer Billing (1999) determined that cultures closest to the equator, where temperatures are hotter, tend to use both a greater number and a wider variety of plant-based spices with bacteria-inhibiting phytochemical properties (e.g., garlic and onion). Antimicrobial properties of spices permits the consumption of foods, particularly animal-based protein sources, for a period of time beyond that which would be considered safe. There are some acclimatory adjustment benefits to the use of some pungent spices as well, which are explored in the following section.<\/p>\n<h4 class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><em>Acclimatory Adjustments: Thermal Stressors<\/em><\/h4>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1846\">Acclimatory adjustments<\/a><\/strong> are temporary, reversible changes in an organism\u2019s physiology in response to environmental stressors. Although they are not genetically determined, the range of acclimatory adjustments that an organism is capable of producing is linked to its underlying phenotypic plasticity and the duration and severity of the stressor. A good example of this is the human response to varying ambient temperatures.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">To understand human adjustments, we must first understand the thermodynamic mechanisms through which heat may be gained or lost. The four pathways for this are conduction, convection, evaporation, and radiation (Figure 15.2).<\/p>\n<figure style=\"width: 376px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image11-5.png\" alt=\"Person facing wall with arrows illustrating evaporation, conduction, radiation, and convection.\" width=\"376\" height=\"426\" \/><figcaption class=\"wp-caption-text\">Figure 15.2: Various thermodynamic mechanisms related to heat gain and loss in the human body. This process is decribed in the text below. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-13\/\" target=\"_blank\">Mechanisms of heat transfer (Figure 14.2)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Through <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1847\">conduction<\/a><\/strong> processes, heat will move from a warmer body to a cooler one through direct contact. An example of this is when you accidentally touch a hot cooktop with your hand and the heat is transferred from the cooktop to your skin.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">With <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1848\"><strong>convection<\/strong><\/a>, when a warm body is surrounded by a cooler fluid (e.g., air or water), heat will be transferred from the warmer body to the cooler fluid. This is why we will often employ the behavioural adjustment of wearing multiple layers of clothing during the winter in an effort to prevent heat loss to the cooler atmosphere. Conversely, if your body temperature is cooler than that of the air surrounding you, your body will absorb heat.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Depending on your physical condition, most people will begin to sweat around 37.2\u2103 to 37.7\u2103 (98.9\u2109\u201399.9\u2109). Sweating is an example of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1849\"><strong>evaporation<\/strong><\/a>, which occurs when a liquid, such as the water within our bodies, is converted to a gas. Phase conversions, such as those underlying the evaporative processes of transforming liquids to gasses, require energy. In evaporation, this energy is in the form of heat, and the effect is to cool the body.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The final mechanism for heat loss within the human body is <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1850\"><strong>radiation<\/strong><\/a>, through which energy in the form of electromagnetic waves is produced at a wavelength that typically lies below that which is visible to the human eye. Although humans gain and lose heat from their bodies through radiation, this form of heat transfer is not visible. Humans are capable of losing and gaining heat through conduction, convection, and radiation; however, heat may not be gained through evaporation.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">As the ambient temperature decreases, it becomes increasingly difficult for the human body to regulate its core temperature, which is central to the maintenance of homeostasis. When an individual\u2019s body temperature falls below 34.4\u2103 (93.9\u00b0F), the brain\u2019s <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1851\">hypothalamus<\/a><\/strong> becomes impaired, leading to issues with body temperature control. A total loss of the ability to regulate body temperature occurs around 29.4\u2103 (84.9\u00b0F), which may result in death. When the ambient temperature falls below the critical temperature of 31\u2103 (87.8\u00b0F), a nude human body that is at rest will respond with a series of physiological changes to preserve homeostasis (Figure 15.3).<\/p>\n<figure style=\"width: 585px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image26-2.jpg\" alt=\"Body outlines illustrate differences in heat maintenance for different ambient environments.\" width=\"585\" height=\"347\" \/><figcaption class=\"wp-caption-text\">Figure 15.3: Example of overall body heat maintenance in cold and warm ambient environments. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\">A full text description of this image is available<\/a>. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-13\/\" target=\"_blank\">Body heat maintenance in cold and warm (Figure 14.3)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The human body experiences two main types of physiological responses to colder temperatures: those that increase the production of heat and those that seek to retain heat. The production of heat within the body is accomplished through short-term increases in the body\u2019s basal metabolic rate, such as shivering to increase muscular metabolism. An organism\u2019s basic metabolic rate is a measure of the energy required to maintain necessary body processes when the organism is at rest. Increases in basal metabolic rates, such as when we shiver from the cold, require increased consumption of energy-providing nutrients. Of course, such increases in metabolic rates are not infinite, as we may only consume a finite amount of nutrients. As with all <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1846\">acclimatory adjustments<\/a><\/strong>, an increase in the basal metabolic rate is merely temporary.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Of the physiological mechanisms to preserve heat already in the body, the most notable is <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1853\"><strong>vasoconstriction<\/strong><\/a>, or the constriction of peripheral capillaries in the skin. The decreased surface area of the capillaries through vasoconstriction results in less heat reaching the surface of the skin where it would be dissipated into the atmosphere. Vasoconstriction also leads to the maintenance of heat near the core of the body where the vital organs are located. As a trade-off, though, individuals are more at risk of cold-related injuries, such as frost-bite, which can lead to tissue necrosis (tissue death) in regions of the body that are most distant from the core (e.g., fingers, toes, nose, ears, cheeks, chin, etc.).<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Just as cold stress presents challenges to maintaining homeostasis, heat does as well. In hot climates, the body will absorb heat from its surroundings (through conduction, convection, and radiation), resulting in potential heat-related disorders, such as heat exhaustion. When the human body is exposed to ambient temperatures above 35\u2103 (95\u00b0F), excess body heat will be lost primarily through evaporative processes, specifically through sweating. All humans, regardless of their environment, have approximately the same number of sweat glands within their bodies. Over time, individuals living in hot, arid environments will develop more sensitive forms of sweat glands resulting in the production of greater quantities of sweat (Best, Lieberman, and Kamilar 2019; Pontzer Et al. 2021). In an effort to prevent dehydration due to this form of acclimatory adjustment, there will be an additional reduction in the volume of urine produced by the individual (Pontzer Et al. 2021).<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">As noted in the previous section, some cultural groups, particularly those in equatorial regions, add pungent spices to their foods to inhibit the colonization of bacteria (Sherman and Billing 1999). Although adding spices to decrease spoilage rates is a behavioural adjustment, the application of some forms of peppers triggers an acclimatory adjustment as well. Compounds referred to as capsaicinoids are the secondary byproducts of chili pepper plants\u2019 metabolism and are produced to deter their consumption by some forms of fungi and mammals. When mammals, such as humans, consume the capsaicinoids from chili peppers, a burning sensation may occur within their mouths and along their digestive tracts. This burning sensation is the result of the activation of capsaicin receptors along the body\u2019s nerve pathways. Although the peppers themselves may be at ambient temperature so their consumption is not causing any form of body temperature increase, the human body perceives the pepper as elevating its core temperature due to the activation of the capsaicin receptors. This causes the hypothalamus to react, initiating sweating in an attempt to lower body temperature and maintain homeostasis. The increased piquancy (application of pungent spices to food) as a means of inhibiting food-borne bacterial colonization in warm climates, as well as spices\u2019 ability to trigger sweating processes as a method for cooling the body, is an example of the intersection between behavioural and acclimatory adjustments that utilized within certain populations.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">In addition to increased sweat production to maintain homeostasis in excess heat, <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1854\">vasodilation<\/a><\/strong> may occur (Figure 15.4). Vasodilation is an expansion of the capillaries within the skin leading to a more effective transfer of heat from within the body to the exterior to allow conductive, convective, radiative, and evaporative (sweating) processes to occur.<\/p>\n<figure style=\"width: 499px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image27-4.png\" alt=\"Side-by-side sketches of capillaries under the skin for heat and cold.\" width=\"499\" height=\"445\" \/><figcaption class=\"wp-caption-text\">Figure 15.4: The vasoconstriction processes occur within the peripheral vascular system when an individual is exposed to cold ambient temperatures and the vasodilation that occurs in warmer environments. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\">A full text description of this image is available<\/a>. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-13\/\" target=\"_blank\">Vasoconstriction and vasodilation (Figure 14.4)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Physiologically based acclimatory adjustments to hot, dry climates may be complemented by behavioural adjustments as well. For example, individuals in such climates may limit their physical activity during the times of day when the temperature is typically the hottest. Additionally, these individuals may wear loose-fitting clothing that covers much of their skin. The looseness of the clothing allows for air to flow between the clothing and the skin to permit the effective evaporation of sweat. Although it may seem counterintuitive to cover one\u2019s body completely in a hot climate, the covering of the skin keeps the sun\u2019s rays from directly penetrating the skin and elevating the body\u2019s core temperature.<\/p>\n<h4 class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><em>Acclimatory Adjustments: Altitudinal Stressors<\/em><\/h4>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The challenges posed by thermal conditions are but one form of environmental stressor humans must face. High-altitude environments, which are defined as altitudes in excess of 2,400 metres above sea level (masl) or 7,874 feet above sea level (fasl), pose additional challenges to the maintenance of homeostasis in humans. Some of the main stressors encountered by those living within high-altitude environments include decreased oxygen availability, cold temperatures, low humidity, high wind speed, a reduced nutritional base, and increased solar radiation levels. Of these challenges, the most significant is the decreased availability of oxygen.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">To visualize how altitude affects the availability of oxygen, imagine two balloons that are each filled with the same quantity of oxygen molecules. One of these balloons is positioned at sea-level and the other is placed high upon a mountain peak. For the balloon at sea level, there is more atmospheric pressure pressing down on the molecules within this balloon. This leads to the oxygen molecules within the sea level balloon being forced into a more compact organization. In contrast, the mountain peak balloon has less atmospheric pressure pressing down on it. This leads to the oxygen molecules within that balloon spreading out from each other since they are not being forced together quite as strongly. This example highlights the availability of oxygen molecules in each breath than we take in low- versus high-altitude environments. At 5,500 masl (approximately 18,000 fasl), the atmospheric pressure is approximately 50% of its value at sea level (Peacock 1998). At the peak of Mount Everest (8,900 masl or approximately 29,200 fasl), the atmospheric pressure is equivalent to only about 30% of their sea level amounts (Peacock 1998; Figure 15.5).<\/p>\n<figure style=\"width: 482px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image21-5.png\" alt=\"Atmospheric pressure decreases in density as a person climbs a mountain and increases in altitude.\" width=\"482\" height=\"418\" \/><figcaption class=\"wp-caption-text\">Figure 15.5: As altitude increases, atmospheric pressure decreases, which allows for more space between air molecules. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-13\/\" target=\"_blank\">Atmospheric pressure (Figure 14.5)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Due to decreased availability of oxygen at higher altitudes, certain acclimatory adjustments are required to ensure the maintenance of homeostasis for individuals other than those who were gestated, born, and raised at high altitude. For these people, their rate of breathing will increase to permit greater quantities of air containing oxygen into the lungs when they ascend into higher altitude environments. An increased speed and depth of breathing, which is referred to as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1855\"><strong>hyperpnea<\/strong><\/a>, is not sustainable indefinitely; thus, the rate of breathing begins to decrease as the person becomes acclimatized to the altitude. During the initial phases of high-altitude-related hyperpnea, the heart begins to beat faster but the amount of blood pushed through during each beat decreases slightly. In addition, the body will divert energy from noncritical bodily functions, such as digestive processes.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Once the atmospheric oxygen reaches the alveoli (small air sacs) in the lungs, it spreads across the alveolar membrane and enters <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1858\">erythrocytes<\/a><\/strong> (red blood cells). As oxygen reaches the alevoli\u2019s erythrocytes, it loosely binds with hemoglobin (an iron-rich protein) contained in the erythrocytes. When the erythrocytes carrying the hemoglobin-bound oxygen molecules reach capillaries where the partial pressure of oxygen is relatively low, oxygen will be released by the hemoglobin so that it is free for diffusion into body cells. Similar to acclimatory adjustments related to thermal conditions (e.g., shivering or sweating), those related to high altitude may not be infinitely sustained due to their energetically expensive nature.<\/p>\n<figure style=\"width: 430px\" class=\"wp-caption alignright\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image24-3.jpg\" alt=\"Newborn lays face down on hospital bedding. Photograph is blue indicating UV light.\" width=\"430\" height=\"323\" \/><figcaption class=\"wp-caption-text\">Figure 15.6: Premature infant born at 30 weeks, 4 days gestation to a mother with altitudinal-induced preeclampsia. Blue light assists the infant\u2019s liver with processing high levels of bilirubin. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-13\/\" target=\"_blank\">Premature infant<\/a> by Leslie E. Fitzpatrick is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Although the long-term acclimatory adjustments that an individual from low altitude experiences in a high-altitude environment may permit them to reside there successfully, reproduction within such settings is frequently complicated. With increased altitude comes an increased risk of miscarriage, lower birth weights, and higher infant mortality rates. As the pregnant person\u2019s body seeks to preserve its own homeostasis, there is often a decreased rate and volume of blood flow to the uterus as compared to a pregnant person of similar physiological condition at a lower altitude (Moore, Niermeyer, and Zamudio 1998). This results in a decrease in the amount of oxygen that will be passed through the uterus and placenta to the developing fetus. In addition, pregnant people who experience pregnancy at higher altitudes are more prone to developing preeclampsia (severe elevation of blood pressure), which is linked to increased rates of both fetal and maternal death (Moore, Niermeyer, and Zamudio 1998; Figure 15.6).<\/p>\n<h4 class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><em>Developmental Adjustments <\/em><\/h4>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Developmental adjustments occur only in individuals who spent their developmental period (i.e., childhood and adolescence) within a high-altitude environment; they do not apply to those who moved into these environments in the post developmental (i.e., adult) phase. Furthermore, the degree of developmental adjustment within an individual is directly related to their underlying phenotypic plasticity as well as the amount of time during the crucial growth and development period that the individual resides within the challenging environment. Although humans have the remarkable capacity to develop and survive within environments that are not overly conducive to the successful maintenance of homeostasis, there are definitely physiological costs associated with this ability.<\/p>\n<figure style=\"width: 369px\" class=\"wp-caption alignleft\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image18-2.jpg\" alt=\"Two people walking down a street wearing brightly colored woven traditional clothing.\" width=\"369\" height=\"277\" \/><figcaption class=\"wp-caption-text\">Figure 15.7: Two individuals from a high-altitude region of the Peruvian Andes. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Andahuaylas_Peru-_two_women_walking_down_street.jpg\" target=\"_blank\">Andahuaylas Peru-two women walking down street<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:ThayneT\" target=\"_blank\">Thayne Tuason<\/a> has been modified (cropped) and is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/deed.en\" target=\"_blank\">CC BY 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">In general, high-altitude natives tend to grow more slowly and physically mature later than their low-altitude counterparts (Figure 15.7). Lowered growth and maturity rates are linked not only to the increased physiological demands placed on the body due to the decreased partial pressure of oxygen but also to reductions in the quality of the nutritional base at higher altitudes. Increased terrain complexity, elevated solar radiation levels, and higher wind speeds coupled with the lower temperatures and humidity levels found at high altitudes leads to difficulties with growing and maintaining crops and raising livestock. Overall, as altitude rises, the quality of the available nutritional base goes down, which is correlated to a lack of the nutrients necessary to ensure proper physiological growth and development in humans. Thus, even though individuals may be able to develop and grow within high-altitude environments, they may not reach their full genetically mediated growth potential as they would in a lower-altitude environment.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Not all developmental adjustments are linked to environmental pressures such as climate or altitude; rather, some of these adjustments are correlated to sociocultural or behavioural practices. Some of these adjustments may affect the physiological appearance of an individual when they are practiced consistently during the development and growth phases.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Sudden infant death syndrome (SIDS) has no definitive cause; however, the American Academy of Pediatrics published a report in 1992 linking SIDS to infants (under the age of one) sleeping on their stomachs. The \u201cBack to Sleep\u201d campaign championed by the American Academy of Pediatrics helped educate members of the medical community as well as the public that the best sleep position for infants is on their backs (American Academy of Pediatrics 2000).<\/p>\n<figure id=\"attachment_420\" aria-describedby=\"caption-attachment-420\" style=\"width: 562px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-419\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/14.8.jpg\" alt=\"Brachycephaly drawings show a flattened, symmetrical head. Plagiocephaly shows asymmetrical flattening of the skull.\" width=\"562\" height=\"219\" \/><figcaption id=\"caption-attachment-420\" class=\"wp-caption-text\">Figure 15.8: These sketches illustrate a top and side view of brachycephaly (left and middle images, respectively) and plagiocephaly (right image). Credit: Brachycephaly and plagiocephaly original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Mary Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<div class=\"__UNKNOWN__\">\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Placing infants on their backs to sleep has led to decreased infant mortality (death) rates due to SIDS; however, it has led to an unintended consequence: infant cranial deformation. The cranial deformations experienced by infants who sleep solely on their back tend to manifest in one of two forms: brachycephaly and plagiocephaly (Roby Et al. 2012; Figure 15.8). With positional brachycephaly, the back of the infant\u2019s head appears rather uniformly flattened due to repetitive contact with a flat surface, such as a crib mattress or car seat back. In cases of positional plagiocephaly, the back of the infant\u2019s head appears asymmetrically flattened. This asymmetry is typically due to an uneven distribution of mechanical forces resulting from the manner in which the infant\u2019s head is in contact with a flat surface. The forms of cranial deformation resulting from sleep positioning do not affect the infant\u2019s brain development. For many individuals, the appearance of the deformation is minimized during later development. Still, some individuals will maintain the pattern of cranial deformation acquired during their infancy throughout their lives. The unintentional cranial deformation resulting from placing infants on their backs to sleep as a means of preventing SIDS-related deaths is a physiological indicator of a behavioural adjustment.<\/p>\n<\/div>\n<h3 class=\"__UNKNOWN__\"><strong>Adaptations<\/strong><\/h3>\n<div class=\"__UNKNOWN__\">\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">As we have just explored, survival and reproduction at high altitudes present numerous physiological challenges for most humans. The behavioural, acclimatory, and developmental adjustments discussed above are all related to the phenotypic plasticity of the individual; however, most adjustments are temporary in nature and they affect a single individual rather than all individuals within a population. But what if the physiological changes were permanent? What if they affected all members of a population rather than just a single individual? The long-term, microevolutionary (i.e., genetic) changes that occur within a population in response to an environmental stressor are referred to as an adaptation. From an evolutionary standpoint, the term <em>adaptation<\/em> refers to a phenotypic trait (i.e., physiological\/morphological feature or behaviour) that has been acted upon by natural selection processes to increase a species\u2019 ability to survive and reproduce within a specific environment. Within the field of physiology, the term <em>adaptation<\/em> refers to traits that serve to restore homeostasis. The physiology-based interpretation of adaptations presumes that all traits serve a purpose and that all adaptations are beneficial in nature; however, this may be a fallacy, since some traits may be present without clear evidence as to their purpose. As such, during the following discussion of various forms of adaptations in human populations, we will focus our attention on phenotypic traits with an evidence-based purpose.<\/p>\n<h4 class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><em>Adaptation: <\/em><em>Altitudinal Adaptation<\/em><\/h4>\n<\/div>\n<figure id=\"attachment_420-2\" aria-describedby=\"caption-attachment-420-2\" style=\"width: 619px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-420\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/14.9.jpg\" alt=\"The Simian Plateau in northeast Africa and Tibetan Plateau in southern Asia.\" width=\"619\" height=\"339\" \/><figcaption id=\"caption-attachment-420-2\" class=\"wp-caption-text\">Figure 15.9: Highlighted regions feature (from left to right) the Simian (Ethiopian) and Tibetan Plateau high-altitude regions. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:World_Map_of_HVR_adaptation_in_high_altitude_populations.jpg\" target=\"_blank\">World Map of HVR adaptation in high altitude populations<\/a> by Chkuu has been modified (cropped, Andean region colour change) and is under <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\" target=\"_blank\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<div class=\"__UNKNOWN__\">\n<p>As mentioned in the previous section, there is genomic research supporting the evolutionary selection of certain phenotypes and their corresponding genotypes within indigenous high-altitude populations across the globe. The following discussion focuses on two high-altitude indigenous populations from Tibet and Ethiopia (Figure 15.9). Although these populations share many common genetic traits based on relatively similar evolutionary histories influenced by similar environmental stressors, there is support for local genetically based adaptation as well, based on different genes being acted upon by environmental stressors that may be unique to Tibet and Ethiopia (Bigham 2016).<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Tibetan populations have resided in the Tibetan Plateau and Himalayan Mountain regions at elevations exceeding 4,000 masl (13,100 fasl) for at least the past 7,400 years (Meyer Et al. 2017). There is evidence of a genetic exchange event involving Tibetan populations and Denisovans around 48,700 years ago, which introduced a haplogroup involving mutations of the <em>EPAS1<\/em> gene (Zhang Et al. 2021). The <em>EPAS1<\/em> is involved in the regulation of erythrocytes and hemoglobin. For individuals originating in lower-altitude environments, <em>EPAS1 <\/em>stimulates increased erythrocyte production in high-altitude environments as a temporary acclimatory adjustment. For indigenous high-altitude populations of Tibet, the <em>EPAS1<\/em> gene mutation introduced by Denisovan introgression inhibits increased erythrocyte production, which reduces potential negative effects (e.g., stroke or heart attack) associated with long-term high levels of erythrocyte production (Gray Et al. 2022; Zhang Et al. 2021). The erythrocyte count of high-altitude Tibetans with the <em>EPAS1<\/em> point mutation is about the same as for individuals residing at sea level.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Populations indigenous to the Semien Plateau of Ethiopia, such as the Oromo and Amhara, share a similar but not identical <em>EPAS1<\/em> point mutation with the Tibetan population (Bigham 2016); however, there is no indication that this mutation was derived from Denisovan introgression. The <em>EPAS1<\/em> mutations occurred independently from each other; however, their effects are still similar in that they permit the Tibetan and Ethiopian populations to survive at high altitudes. Not all adaptations are related to life in high-altitude environments, however. In the following sections, we will address two more general examples of adaptation in human populations: variations in skin colour and differences in body build.<\/p>\n<h4 class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><em>Adaptation: Skin Tone<\/em><em> Basics<\/em><\/h4>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">When you think about your own skin tone and compare it to members of your family, do you all possess exactly the same shade? Are some members of your family darker than others? What about your friends? Your classmates? Skin tone occurs along a continuum, which is a reflection of the complex evolutionary history of our species. The expression of skin tone is regulated primarily by melanin and hemoglobin. <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1871\">Melanin<\/a><\/strong> is a dark brown-black pigment that is produced by the oxidation of certain amino acids (e.g., tyrosine, cysteine, phenylalanine) in melanocytes. <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1872\">Melanocytes<\/a><\/strong> are specialized cells located in the base layer (stratum basale) of the skin\u2019s epidermis as well as several other areas within the body (Figure 15.10). Within the melanocytes, melanin is produced in the special organelle called a melanosome. Melanosomes serve as sites for the synthesis, storage, and transportation of melanin. Melanosomes transport the melanin particles through cellular projections to epidermal skin cells (keratinocytes) as well as to the base of the growing hair root. In the eye, however, melanin particles produced by the melanosomes remain present within the iris and are not transported beyond their origin location. The two main forms of melanin related to skin, hair, and eye colour are eumelanin and pheomelanin. All humans contain both eumelanin and pheomelanin within their bodies; however, the relative expression of these two forms of melanin determines an individual\u2019s overall colouring. Eumelanin is a brown-to-black coloured melanin particle while pheomelanin is more pink-to-red coloured. Individuals with darker skin or hair colour have a greater expression of eumelanin than those with lighter-coloured skin and blonde or red hair.<\/p>\n<figure style=\"width: 553px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image12-2.jpg\" alt=\"Melanocytes and melanosomes are compared from light and dark skin tones.\" width=\"553\" height=\"436\" \/><figcaption class=\"wp-caption-text\">Figure 15.10: Diagram featuring the relative numbers of melanocytes and melanosomes in light and dark shades of skin tone. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\">A full text description of this image is available<\/a>. Credit: <a href=\"https:\/\/openstax.org\/books\/anatomy-and-physiology-2e\/pages\/5-1-layers-of-the-skin#fig-ch05_01_07\" target=\"_blank\">Skin Pigmentation (Anatomy and Physiology, Figure 5.8)<\/a> by <a href=\"https:\/\/openstax.org\/\" target=\"_blank\">OpenStax<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\" target=\"_blank\">CC BY 4.0 License<\/a>.<\/figcaption><\/figure>\n<h4 class=\"import-Normal\"><em>Adaptation<\/em><em>: <\/em><em>Melanogenesis <\/em><\/h4>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Although all humans have approximately the same number of melanocytes within their epidermis, the production of melanin by these melanocytes varies. There are two forms of melanogenesis (the process through which melanocytes generate melanin): basal and activated. As discussed previously, the expression of eumelanin and pheomelanin by the melanocytes is genetically regulated through the expression of specific receptors (e.g., <em>MC1R<\/em>) or other melanocyte components (e.g., <em>MFSD12<\/em>)<em>.<\/em> <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1873\">Basal melanogenesis<\/a> <\/strong>is dependent upon an individual\u2019s inherent genetic composition and is not influenced by external factors. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1874\"><strong>Activated melanogenesis<\/strong><\/a> occurs in response to ultraviolet radiation (UV) exposure, specifically UV-B (short UV wave) exposure. Increased melanogenesis in response to UV-B exposure serves to provide protection to the skin\u2019s innermost layer called the hypodermis, which lies below the epidermis and dermis (Figure 15.11). Melanin in the skin, specifically eumelanin, effectively absorbs UV-B radiation from light\u2014meaning that it will not reach the hypodermal layer. This effect is often more apparent during periods of the year when people tend to be outside more and the weather is warmer, which leads to most donning fewer protective garments. The exposure of skin to sunlight is, of course, culturally mediated with some cultures encouraging the covering of skin at all times.<\/p>\n<figure style=\"width: 395px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image10-6.png\" alt=\"Cross-section of skin illustrating UVA rays penetrate deeper than UVB.\" width=\"395\" height=\"407\" \/><figcaption class=\"wp-caption-text\">Figure 15.11: Penetration of skin layers by UVA and UVB rays. UVB rays penetrate only through the epidermis. UVA rays penetrate much deeper, through the dermis. Credit: <a href=\"https:\/\/cnx.org\/contents\/FPtK1zmh@16.7:RxywCGkA@10\/5-1-Layers-of-the-Skin\" target=\"_blank\">Skin Pigmentation (Anatomy and Physiology, Figure 5.8)<\/a> by<a href=\"https:\/\/openstax.org\/\" target=\"_blank\"> OpenStax<\/a> is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\" target=\"_blank\"> CC BY 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">As previously noted in this chapter, hemoglobin is an iron-rich protein that binds with oxygen in the bloodstream. For individuals with lighter-coloured skin, blood vessels near the surface of the skin and the hemoglobin contained within those vessels is more apparent than in individuals with darker skin. The visible presence of hemoglobin coupled with the pink-to-red tone of the pheomelanin leads to lighter-skinned individuals having a pale pink skin tone. Individuals with lighter skin more readily absorb UV radiation as their basal melanin expression is directed more toward the production of pheomelanin than eumelanin. But why are there so many variations in skin tone in humans? To answer this question, we now turn toward an exploration of an evolutionary-based adaptation of skin tone as a function of the environment.<\/p>\n<h4 class=\"import-Normal\"><em>Adaptation: <\/em><em>Evolutionary Basis for Skin Tone Variation<\/em><\/h4>\n<figure style=\"width: 337px\" class=\"wp-caption alignleft\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image22-4.png\" alt=\"Table discussing hair and skin, folate and UV rays, leaving Africa, vitamin D, and selective pressures.\" width=\"337\" height=\"843\" \/><figcaption class=\"wp-caption-text\">Figure 15.12: Evolutionary basis for human skin colour variation. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\">A full text description of this image is available<\/a>. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-13\/\" target=\"_blank\">Evolutionary basis for human skin color variation (Figure 14.12)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Katie Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Skin cancer is a significant concern for many individuals with light skin tone as the cumulative exposure of the epidermis and underlying skin tissues to UV radiation may result in the development of abnormal cells within those tissues, leading to malignancies. Although darker-skinned individuals are at risk for skin cancer as well, they are less likely to develop it due to increased levels of melanin, specifically eumelanin, in their skin. Even though skin cancer is a serious health concern for some individuals, most skin cancers occur in the postreproductive years; therefore, it is improbable that evolutionary forces favouring varying melanin expression levels are related to a selective pressure to avoid such cancers. Furthermore, if avoiding skin cancer were the primary factor driving the evolution of various skin tones, then it reasons that everyone would have the most significant expression of eumelanin possible. So, why do we have different skin tones (Figure 15.12)?<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The term <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1875\">cline<\/a><\/strong> (introduced in Chapter 14) refers to the continuum or spectrum of gradations (i.e., levels or degrees) from one extreme to another. With respect to skin tone, the various tonal shades occur clinally with darker skin being more prevalent near the equator and gradually decreasing in tone (i.e., decreased melanin production) in more distant latitudes. For individuals who are indigenous to equatorial regions, the increased levels of melanin within their skin provides them with a measure of protection against both sunburn and sunstroke because the melanin is more reflective of UV radiation than hemoglobin. In cases of severe sunburn, eccrine glands are affected, resulting in an individual\u2019s ability to sweat being compromised. As sweat is the body\u2019s most effective means of reducing its core temperature to maintain homeostasis, damage to the eccrine glands may lead to numerous physiological issues related to heat that may ultimately result in death.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Even though avoiding severe sunburn and sunstroke is of great importance to individuals within equatorial regions, this is likely not the primary factor driving the evolutionary selection of darker skin within these regions. It has been proposed that UV radiation\u2019s destruction of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1876\"><strong>folic acid<\/strong><\/a>, which is a form of B-complex vitamin, may have led to the selection of darker skin in equatorial regions. For pregnant people, low levels of folic acid within the body during gestation may lead to defects in the formation of the brain and spinal cord of the fetus. This condition, which is referred to as spina bifida (Figure 15.13), often significantly reduces an infant\u2019s chances of survival without medical intervention. In people producing sperm, low levels of folic acid within the body reduce sperm quantity and quality. Thus, in geographic regions with high UV radiation levels (i.e., equatorial regions), there appears to be an evolutionarily driven correlation between darker skin and fertility.<\/p>\n<figure style=\"width: 364px\" class=\"wp-caption alignright\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image19-2-1.jpg\" alt=\"Infant with a bulging spinal cord above the lower spine.\" width=\"364\" height=\"294\" \/><figcaption class=\"wp-caption-text\">Figure 15.13: Infant with open neural tube defect in lower (lumbar) region of the spine (right). A close-up of the open neural tube defect within the spinal column (left) shows the dura matter, which is ordinarily protected within the spine, is exposed on the surface of the skin. The spinal cord sits near the surface, when it should be protected within the spinal column. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Spina-bifida.jpg\" target=\"_blank\">Spina-bifida<\/a> by the <a href=\"https:\/\/www.cdc.gov\/\" target=\"_blank\">Centers for Disease Control and Prevention<\/a> is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\" target=\"_blank\">public domain<\/a>.<\/figcaption><\/figure>\n<p>If darker skin tone is potentially correlated to more successful reproduction, then why do lighter shades of skin exist? One hypothesis is that there is a relationship between lighter skin tone and vitamin D synthesis within the body. When skin is exposed to the UV-B radiation waves in sunlight, a series of chemical reactions occur within the epidermis leading to the production of vitamin D3, which is a fat-soluble vitamin that assists the body with absorbing calcium and phosphorus in the small intestine. These nutrients are among those that are critical for the proper growth and maintenance of bone tissue within the body. In the absence of adequate minerals, particularly calcium, bone structure and strength will be compromised, leading to the development of rickets during the growth phase. Rickets is a disease affecting children during their growth phase. It is characterized by inadequately calcified bones that are softer and more flexible than normal. Individuals with rickets will develop a true bowing of their legs, which may affect their mobility (Figure 15.14). In addition, deformation of pelvic bones in people who may become pregnant may occur as a result of rickets, leading to complications with reproduction. In adults, a deficiency in vitamin D3 will often result in osteomalacia, which is a general softening of the bones due to inadequate mineralization. As noted, a variety of maladies may occur due to the inadequate production or absorption of vitamin D3, as well as the destruction of folate within the human body. Therefore, from an evolutionary perspective, natural selection should favour a skin tone that is best suited to a given environment.<\/p>\n<figure style=\"width: 263px\" class=\"wp-caption alignleft\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image9-2-1.jpg\" alt=\"Historic photo of three young children each with visible lower limb curvature.\" width=\"263\" height=\"315\" \/><figcaption class=\"wp-caption-text\">Figure 15.14: Children with rickets in various developmental stages. Credit: <a href=\"https:\/\/wellcomecollection.org\/works\/m3eu5snb\" target=\"_blank\">Rachitis, stages of development for children<\/a> [slide numbers 7181 and 7182; photo number: M0003399] by <a href=\"https:\/\/wellcomecollection.org\/\" target=\"_blank\">Wellcome Collection<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\" target=\"_blank\">CC BY 4.0 License<\/a>.<\/figcaption><\/figure>\n<p>In general, the trend related to lighter skin pigmentation further from the equator follows a principle called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1877\"><strong>Gloger\u2019s Rule<\/strong><\/a>. This rule states that within the same species of mammals the more heavily pigmented individuals tend to originate near the equator while lighter-pigmented members of the species will be found in regions further from the equator. Gloger\u2019s Rule applies latitudinally; however, it does not appear to hold for certain human populations near the poles. Specifically, it does not apply to the Inuit people (Figure 15.15), who are indigenous to regions near the North Pole and currently reside in portions of Canada, Greenland, Alaska, and Denmark. The Inuit have a darker skin tone that would not be anticipated under the provisions of Gloger\u2019s Rule. The high reflectivity of light off of snow and ice, which is common in polar regions, necessitates the darker skin tone of these individuals to prevent folic acid degradation just as it does for individuals within equatorial regions. The consumption of vitamin D\u2013rich foods, such as raw fish, permits the Inuit to reside at high latitudes with darker skin tone while preventing rickets.<\/p>\n<h4 class=\"import-Normal\"><em>Adaptation: <\/em><em>Shape and Size Variations<\/em><\/h4>\n<figure style=\"width: 353px\" class=\"wp-caption alignright\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image6-3-1.jpg\" alt=\"Historic photo of a person carrying a very large fish laid on a pack.\" width=\"353\" height=\"296\" \/><figcaption class=\"wp-caption-text\">Figure 15.15: Copper Inuk (from Bernard Harbour, Nunavut) with lake trout on his back (1915). Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Copper_Inuk_with_lake_trout_on_his_back_near_Bernard_Harbour_(51007).jpg\" target=\"_blank\">Copper Inuk with lake trout on his back near Bernard Harbour, Northwest Territories (Nunavut)<\/a> (1915) by George H. Wilkins is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/deed.en\" target=\"_blank\">CC BY-SA 4.0 License<\/a>. This image is part of the Photographic Archives of the Canadian Museum of History.<\/figcaption><\/figure>\n<p>In addition to natural selection playing a role in the determination of melanin expression, it plays a significant role in the determination of the shape and size of the human body. As previously discussed, the most significant thermodynamic mechanism of heat loss from the body is radiation. At temperatures below 20\u2103 (68\u2109), the human body loses around 65% of its heat to radiative processes; however, the efficiency of radiation is correlated to the overall body shape and size of the individual. There is a direct correlation between the ratio of an object\u2019s surface area to mass and the amount of heat that may be lost through radiation. For example, two objects of identical composition and mass are heated to the same temperature. One object is a cube and the other is a sphere. Which object will cool the fastest? Geometrically, a sphere has the smallest surface area per unit mass of any three-dimensional object, so the sphere will cool more slowly than the cube. In other words, the smaller the ratio of the surface area to mass an object has, the more it will retain heat. With respect to the cube in our example, mass increases by the cube, but surface area may increase only by the square, so size will affect the mass to surface area ratio. This, in general, holds true for humans, as well.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">In regions where temperatures are consistently cold, the body shape and size of individuals indigenous to the area tend to be more compact. These individuals have a relatively higher body mass to surface area (i.e., skin) than their counterparts from equatorial regions where the average temperatures are considerably warmer. Individuals from hot climates, such as the Fulani (Figure 15.16) of West Africa, have limbs that are considerably longer than those of individuals from cold climates, such as the Inuit of Greenland (Figure 15.16). Evolutionarily, the longer limbs of individuals from equatorial regions (e.g., the Fulani) provide a greater surface area (i.e., lower body mass to surface area ratio) for the dissipation of heat through radiative processes. In contrast, the relatively short limbs of Arctic-dwelling people, such as the Inuit, allows for the retention of heat because there is a decreased surface area through which heat may radiate away from the body.<\/p>\n<figure style=\"width: 385px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image20-2.jpg\" alt=\"Person on left is stocky, person on right has a narrow body breadth.\" width=\"385\" height=\"570\" \/><figcaption class=\"wp-caption-text\">Figure 15.16: The individual on the left is typical of one adapted to a cold environment where the conservation of heat in the body\u2019s core is of critical importance.The individual on the right could be adapted to a tropical environment where the rapid dispersal of heat is necessary to maintain homeostasis. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Greenland_1999_(01).jpg\" target=\"_blank\">Greenland 1999 (01)<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Vadeve\" target=\"_blank\">Vadeve<\/a> has been designated to the <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/cc0\/\" target=\"_blank\">public domain (CC0)<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">As described above, there are certain trends related to the general shape and size of human bodies in relation to the thermal conditions. To better describe these trends, we turn to a couple of general principles that are applicable to a variety of species beyond humans. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1879\"><strong>Bergmann\u2019s Rule<\/strong><\/a> predicts that as average environmental temperature decreases, populations are expected to exhibit an increase in weight and a decrease in surface area (Figure 15.17a). Also, within the same species of homeothermic animals, the relative length of projecting body parts (e.g., nose, ears, and limbs) increases in relation to the average environmental temperature (Figure 15.17b). This principle, referred to as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1880\"><strong>Allen\u2019s Rule<\/strong><\/a>, notes that longer, thinner limbs are advantageous for the radiation of excess heat in hot environments and shorter, stockier limbs assist with the preservation of body heat in cold climates. A measure of the crural index (crural index = tibia length <span style=\"font-size: NaNpt;color: #;text-decoration: none\">\u00f7 <\/span>femur length) of individuals from various human populations provides support for Allen\u2019s Rule since this value is lower in individuals from colder climates than it is for those from hot climates. The crural indices for human populations vary directly with temperature, so individuals with higher crural index values are generally from regions with a warmer average environmental temperature. Conversely, the crural indices are lower for individuals from regions where there are colder average temperatures.<\/p>\n<figure style=\"width: 533px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image16-6.png\" alt=\"Illustration of an elk (left) and gazelle (right).\" width=\"533\" height=\"319\" \/><figcaption class=\"wp-caption-text\">Figure 15.17a: These organisms are representative of Bergmann\u2019s rule. The animal on the left depicts an ungulate from a cooler environment with increased body weight and decreased surface area, compared to the slender ungulate on the right. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-13\/\" target=\"_blank\">Bergmann\u2019s Rule (Figure 14.16a)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<figure style=\"width: 521px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image14-4.png\" alt=\"Three types of rabbits with different ear and forelimb lengths.\" width=\"521\" height=\"264\" \/><figcaption class=\"wp-caption-text\">Figure 15.17b: These animals are representative of Allen\u2019s rule. The rabbit on the left comes from a cooler environment and is compact with short limbs and ears. The rabbit on the right comes from a warm environment and has long and lanky limbs and ears. The rabbit in the middle has ears and limbs that are in-between the other two. Rabbits do not sweat like humans; heat is dissipated primarily through their ears. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-13\/\" target=\"_blank\">Allen\u2019s Rule (Figure 14.16b)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<figure style=\"width: 627px\" class=\"wp-caption alignleft\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image17-6.png\" alt=\"Four noses with varying heights, arches, and nostril breadth.\" width=\"627\" height=\"237\" \/><figcaption class=\"wp-caption-text\">Figure 15.18: Human nasal morphological variation as influenced by four major climate-based adaptive zones: hot-dry, hot-wet, cold-dry, and cold-wet. The four noses in this figure vary in shape in relation to their respective climate-based adaptive zones. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-13\/\" target=\"_blank\">Human nasal morphological variation (Figure 14.17)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p>Nasal shape and size (Figure 15.18) is another physiological feature affected by our ancestors\u2019 environments. The selective role of climate in determining human nasal variation is typically approached by dividing climates into four adaptive zones: hot-dry, hot-wet, cold-dry, and cold-wet (Maddux Et al. 2016). A principal role of the nasal cavity is to condition (i.e., warm and humidify) ambient air prior to its reaching the lungs. Given this function of the nasal cavity, it is anticipated that different nasal shapes and sizes will be related to varying environments. In cold-dry climates, an individual\u2019s nasal cavity must provide humidification and warmth to the dry air when breathing in through the nose (Noback Et al. 2011). Also, in that type of climate, the nasal cavity must conserve moisture and minimize heat loss during when the individual exhales through the nose (Noback Et al. 2011). From a physiological stress perspective, this is a stressful event.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Conversely, in hot-wet environments, there is no need for the nasal cavity to provide additional moisture to the inhaled air nor is there a need to warm the air or to preserve heat within the nasal cavity (Noback Et al. 2011). So, in hot-wet climates, the body is under less physiological stress related to the inhalation of ambient air than in cold-dry climates. As with most human morphological elements, the shape and size of the nasal cavity occurs along a cline. Due to the environmental stressors of cold-dry environments requiring the humidification and warming of air through the nasal cavity, individuals indigenous to such environments tend to have taller (longer) noses with a reduced nasal entrance (nostril opening) size (Noback Et al. 2011). This general shape is referred to as leptorrhine, and it allows for a larger surface area within the nasal cavity itself for the air to be warmed and humidified prior to entering the lungs (Maddux Et al. 2016). In addition, the relatively small nasal entrance of leptorrhine noses serves as a means of conserving moisture and heat (Noback Et al. 2011). Individuals indigenous to hot-wet climates tend to have platyrrhine nasal shapes, which are shorter with broader nasal entrances (Maddux Et al. 2016). Since individuals in hot-wet climates do not need to humidify and warm the air entering the nose, their nasal tract is shorter and the nasal entrance wider to permit the effective cooling of the nasal cavity during respiratory processes.<\/p>\n<h4 class=\"import-Normal\"><em>Adaptation: Infectious Disease<\/em><\/h4>\n<p class=\"import-Normal\">Throughout our evolutionary journey, humans have been exposed to numerous infectious diseases. In the following section, we will explore some of the evolutionary-based adaptations that have occurred in certain populations in response to the stressors presented by select infectious diseases. One of the primary examples of natural selection processes acting on the human genome in response to the presence of an infectious disease is the case of the relationship between the sickle-cell anemia trait and malaria, introduced in Chapter 5.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Malaria is a zoonotic disease (an infectious disease transmitted between animals and humans; it is covered in more detail in Chapter 17). It is caused by the spread of the parasitic protozoa from the genus <em>Plasmodium <\/em>(Figure 15.19). These unicellular, eukaryotic protozoa are transmitted through the bite of a female <em>Anopheles<\/em> mosquito. During the bite process, the protozoan parasites present within an infected mosquito\u2019s saliva enter a host\u2019s bloodstream where they are transported to the liver. Within the liver, the parasites multiply and are eventually released into the bloodstream, where they infect erythrocytes. Once inside the erythrocytes, the parasites reproduce until they exceed the cell\u2019s storage capacity, causing it to burst and release the parasites into the bloodstream once again. This replication cycle continues as long as there are viable erythrocytes within the host to infect.<\/p>\n<figure style=\"width: 518px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image13-1-1.jpg\" alt=\"Life cycle stages of Malaria parasite.\" width=\"518\" height=\"511\" \/><figcaption class=\"wp-caption-text\">Figure 15.19: Life cycle of the malaria parasite. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\">A full text description of this image is available<\/a>. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Malaria_parasite_life_cycle-NIAID.jpg\" target=\"_blank\">Malaria parasite life cycle-NIAID<\/a> by <a href=\"https:\/\/www.niaid.nih.gov\/\" target=\"_blank\">NIH National Institute of Allergy and Infectious Diseases<\/a> is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\" target=\"_blank\">public domain<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">General complications from malaria infections include the following: enlargement of the spleen (due to destruction of infected erythrocytes); lower number of thrombocytes (also called platelets, required for coagulation\/clotting of blood); high levels of bilirubin (a byproduct of hemoglobin breakdown in the liver) in the blood; jaundice (yellowing of the skin and eyes due to increased blood bilirubin levels); fever; vomiting; retinal (eye) damage; and convulsions (seizures). In 2020, there were 241 million cases of malaria reported globally, with 95% of those cases originating in Africa (World Health Organization 2021). In sub-Saharan Africa, where incidents of malaria are the highest in the world, 125 million pregnancies are affected by malaria, resulting in 200,000 infant deaths (Hartman, Rogerson, and Fischer 2013). Pregnant people who become infected during the gestational process are more likely to have low-birthweight infants due to prematurity or growth restriction inside the uterus (Hartman, Rogerson, and Fischer 2013). After birth, infants born to malaria-infected pregnant people are more likely to develop infantile anemia (low red-blood cell counts), a malaria infection that is not related to the maternal malarial infection, and they are more likely to die than infants born to non-malaria-infected pregnant people (Hartman, Rogerson, and Fischer 2013).<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">For children and adolescents whose brains are still developing, there is a risk of cognitive (intellectual) impairment associated with some forms of malaria infections (Fernando, Rodrigo, and Rajapakse 2010). Given the relatively high rates of morbidity (disease) and mortality (number of deaths) associated with malaria, it is plausible that this disease may have served as a selective pressure during human evolution. Support for natural selection related to malaria resistance is related to genetic mutations associated with sickle cell, thalassemia, glucose-6-phosphate dehydrogenase (G6PD) deficiency, and the absence of certain antigens (molecules capable of inducing an immune response from the host) on erythrocytes. For the purposes of this text, we will focus our discussion on the relationship between sickle cell disease and malaria.<\/p>\n<figure style=\"width: 312px\" class=\"wp-caption alignright\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image15-2-1.jpg\" alt=\"Normal (round) and sickle (crescent-shaped) red blood cells flow through a blood vessel.\" width=\"312\" height=\"499\" \/><figcaption class=\"wp-caption-text\">Figure 15.20: Normal and sickled erythrocytes. Normal red blood cells are round and can easily flow freely through blood vessels. Abnormal, or cicle, blood cells are half moon shaped and can easily become entangled and block blood flow. Sickle cells have abnormal hemoglobin that form strands that cause the sickle shape. The Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Sickle_cell_01.jpg\" target=\"_blank\">Sickle cell 01<\/a> by <a href=\"https:\/\/www.nhlbi.nih.gov\/health\/sickle-cell-disease\" target=\"_blank\">The National Heart, Lung, and Blood Institute (NHLBI)<\/a> is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\" target=\"_blank\">public domain<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1881\">Sickle cell disease<\/a><\/strong> is a group of genetically inherited blood disorders characterized by an abnormality in the shape of the hemoglobin within erythrocytes. It is important to note that there are multiple variants of hemoglobin, including, but not limited to the following: A, D, C, E, F, H, S, Barts, Portland, Hope, Pisa, and Hopkins. Each of these variants of hemoglobin may result in various conditions within the body; however, for the following explanation we will focus solely on variants A and S.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Individuals who inherit a mutated gene (hemoglobin with a sickled erythrocyte variety, HbS) on chromosome 11 from both parents will develop sickle cell anemia, which is the most severe form of the sickle cell disease family (Figure 15.20). The genotype of an individual with sickle cell anemia is HbSS; whereas, an individual without sickle cell alleles has a genotype of HbAA representing two normal adult hemoglobin type A variants. Manifestations of sickle cell anemia (HbSS) range from mild to severe, with some of the more common symptoms being anemia, blood clots, organ failure, chest pain, fever, and low blood-oxygen levels. In high-income countries with advanced medical care, the median life expectancy of an HbSS individual is around 60 years; however, in low-income countries where advanced medical care is scarce, as many as 90% of children with sickle cell disease perish before the age of five (Longo Et al. 2017).<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Considering that advanced medical care was not available during much of human evolutionary history, it stands to reason that the majority of individuals with the HbSS genotype died before the age of reproduction. If that is the case though, why do we still have the HbS variant present in modern populations? As covered earlier in this textbook, the genotype of an individual is composed of genes from both biological parents. In the case of an individual with an HbSS genotype, the sickle cell allele (HbS) was inherited from each of the parents. For individuals with the heterozygous genotype of HbSA, they have inherited both a sickle cell allele (HbS) and a normal hemoglobin allele (HbA). Heterozygous (HbSA) individuals who reside in regions where malaria is endemic may have a selective advantage. They will experience a sickling of some, but not all, of their erythrocytes. As discussed in the following paragraph, HbSA heterozygous individuals are less likely to die from malaria infections than their HbAA counterparts. Unlike an individual with the HbSS genotype, someone with HbSA may experience some of the symptoms listed above; however, they are generally less severe.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">As noted earlier, the mechanism through which <em>Plasmodium<\/em> protozoan parasites replicate involves human erythrocyte cells. However, due to their sickled shape, as well as the presence of an abnormally shaped protein within the cell, the parasites are unable to replicate effectively in the erythrocyte cells coded for by the HbS allele (Cyrklaff Et al. 2011). An individual who has an HbSA genotype and an active malaria infection will become ill with the disease to a lesser extent than someone with an HbAA genotype, which increases their chances of survival. Although normal erythrocytes (regulated by the HbA allele) allow for parasite replication, they are not able to replicate in HbS erythrocytes of the heterozygote. So, individuals with the HbSA genotype are more likely to survive a malaria infection than an individual who is HbAA. Although individuals with the HbSA genotype may endure some physiological complications related to the sickling of some of their erythrocytes, their morbidity and mortality rates are lower than they are for HbSS members of the population. The majority of individuals who are heterozygous or homozygous for the HbS trait have ancestors who originated in sub-Saharan Africa, India, Saudi Arabia, and regions in South and Central America, the Mediterranean (Turkey, Greece, and Italy), and the Caribbean (Centers for Disease Control and Prevention 2017; Figure 15.21).<\/p>\n<figure style=\"width: 511px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image23-3.png\" alt=\"Map illustrating distribution of sickle cell and associated erythrocytic abnormalities for Africa and Asia.\" width=\"511\" height=\"306\" \/><figcaption class=\"wp-caption-text\">Figure 15.21: Distribution of sickle cell and associated erythrocytic abnormalities for Africa and Asia. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Red_Blood_Cell_abnormalities.png\" target=\"_blank\">Red Blood Cell abnormalities<\/a> by Armando Moreno Vranich has been designated to the <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/cc0\/\" target=\"_blank\">public domain (CC0)<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">With respect to the history of these regions, during the early phases of settlement horticulture was the primary method of crop cultivation. Typically performed on a small scale, horticulture is based on manual labour and relatively simple hand tools rather than the use of draft animals or irrigation technologies. Common in horticulture is <em>swidden<\/em>, or the cutting and burning of plants in woodland and grassland regions. The swidden is the prepared field that results following a slash-and-burn episode. This practice fundamentally alters the soil chemistry, removes plants that provide shade, and increases the areas where water may pool. This anthropogenically altered landscape provides the perfect breeding ground for the <em>Anopheles<\/em> mosquito, as it prefers warm, stagnant pools of water (Figure 15.22).<\/p>\n<figure style=\"width: 561px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image5-6.png\" alt=\"Horticulture encourages mosquitos, increasing malaria. Balancing selection maintains normal and sickle cell alleles.\" width=\"561\" height=\"468\" \/><figcaption class=\"wp-caption-text\">Figure 15.22: The effects of human horticultural activities on the balancing selection of populations in relation to sickle cell disease genotype variants. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\">A full text description of this image is available<\/a>. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-13\/\" target=\"_blank\">Sickle cell disease (Figure 14.21)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Katie Nelson is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>. [Includes two horticulture illustrations by Mary Nelson, <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Sickle_cell_anemia.jpg\" target=\"_blank\">Sickle cell anemia<\/a> by <a href=\"https:\/\/en.wikibooks.org\/wiki\/User:Pkleong\" target=\"_blank\">Pkleong<\/a> at <a href=\"https:\/\/en.wikibooks.org\/wiki\/\" target=\"_blank\">English Wikibooks<\/a> (modified), <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/cc0\/\" target=\"_blank\">public domain (CC0)<\/a>.]<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Although swidden agriculture was historically practiced across the globe, it became most problematic in the regions where the <em>Anopheles<\/em> mosquito is endemic. These areas have the highest incidence rates of malaria infection. Over time, the presence of the <em>Anopheles<\/em> mosquito and the <em>Plasmodium<\/em> parasite that it transmitted acted as a selective pressure, particularly in regions where swidden agricultural practices were common, toward the selection of individuals with some modicum of resistance against the infection. In these regions, HbSS and HbSA individuals would have been more likely to survive and reproduce successfully. Although individuals and populations are far more mobile now than they have been throughout much of history, there are still regions where we can see higher rates of malaria infection as well as greater numbers of individuals with the HbS erythrocyte variant. The relationship between malaria and the selective pressure for the HbS variant is one of the most prominent examples of natural selection in the human species within recent evolutionary history.<\/p>\n<h4 class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><em>Adaptation: Lactase Persistence <\/em><\/h4>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">With the case of sickled erythrocytes and their resistance to infection by malaria parasites, there is strong support for a cause-and-effect-style relationship linked to natural selection. Although somewhat less apparent, there is a correlation between lactase persistence and environmental challenges. Lactase-phlorizin hydrolase (LPH) is an enzyme that is primarily produced in the small intestine and permits the proper digestion of lactose, a disaccharide (composed of two simple sugars: glucose and galactose) found in the milk of mammals. Most humans will experience a decrease in the expression of LPH following weaning, leading to an inability to properly digest lactose. Generally, LPH production decreases between the ages of two and five and is completely absent by the age of nine (Dzialanski Et al. 2016). For these individuals, the ingestion of lactose may lead to a wide variety of gastrointestinal ailments, including abdominal bloating, increased gas, and diarrhea. Although the bloating and gas are unpleasant, the diarrhea caused by a failure to properly digest lactose can be life-threatening if severe enough due to the dehydration it can cause. Some humans, however, are able to produce LPH far beyond the weaning period.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Individuals who continue to produce LPH have what is referred to as the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1882\">lactase persistence<\/a> <\/strong>trait. The lactase persistence trait is encoded for a gene called <em>LCT<\/em>, which is located on human chromosome 2 (Ranciaro Et al. 2014). From an evolutionary and historical perspective, this trait is most commonly linked to cultures that have practiced cattle domestication (Figure 15.23). For individuals in those cultures, the continued expression of LPH may have provided a selective advantage. During periods of environmental stress, such as a drought, if an individual is capable of successfully digesting cow\u2019s milk, they have a higher chance of survival than someone who suffers from diarrhea-linked dehydration due to a lack of LPH. Although the frequency of the lactase persistence trait is relatively low among African agriculturalists, it is high among pastoralist populations that are traditionally associated with cattle domestication, such as the Tutsi and Fulani, who have frequencies of 90% and 50%, respectively (Tishkoff Et al. 2007).<\/p>\n<figure style=\"width: 632px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image4-4.png\" alt=\"Map depicting the percentage of adults with lactase persistence in the eastern hemisphere.\" width=\"632\" height=\"497\" \/><figcaption class=\"wp-caption-text\">Figure 15.23: Interpolated map depicting the percentage of adults with the lactase persistence genotype in indigenous populations of Africa, Europe, Asia, and Australia. Circles denote sample locations. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Lactose_tolerance_in_the_Old_World.svg\" target=\"_blank\">Lactose tolerance in the Old World<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Joe_Roe\" target=\"_blank\">Joe Roe<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/legalcode\" target=\"_blank\">CC BY 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Cattle domestication began around 11,000 years ago in Europe (Beja-Pereira Et al. 2006) and 7,500 to 9,000 years ago in the Middle East and North Africa (Tishkoff Et al. 2007). Based on human genomic studies, it is estimated that the mutation for the lactase persistence trait occurred around 2,000 to 20,000 years ago for European populations (Tishkoff Et al. 2007). For African populations, the lactase persistence trait emerged approximately 1,200 to 23,000 years ago (Gerbault Et al. 2011). This begs the question: Is this mutation the same for both populations? It appears that the emergence of the lactase persistence mutation in non-European populations, specifically those in East Africa (e.g., Tutsi and Fulani), is a case of <strong>convergent evolution<\/strong>. With convergent evolution events, a similar mutation may occur in species of different lineages through independent evolutionary processes. Based on our current understanding of the genetic mutation pathways for the lactase persistence trait in European and African populations, these mutations are not representative of a shared lineage. In other words, just because a person of European origin and a person of African origin can each digest milk due to the presence of the lactase-persistence trait in their genotypes, it does not mean that these two individuals inherited it due to shared common ancestry.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Is it possible that the convergent evolution of similar lactase-persistence traits in disparate populations is merely a product of genetic drift? Or is there evidence for natural selection? Even though 23,000 years may seem like a long time, it is but a blink of the proverbial evolutionary eye. From the perspective of human evolutionary pathways, mutations related to the <em>LCT<\/em> gene have occurred relatively recently. Similar genetic changes in multiple populations through genetic drift processes, which are relatively slow and directionless, fail to accumulate as rapidly as lactase-persistence traits (Gerbault Et al. 2011). The widespread accumulation of these traits in a relatively short period of time supports the notion that an underlying selective pressure must be driving this form of human evolution. Although to date no definitive factors have been firmly identified, it is thought that environmental pressures are likely to credit for the rapid accumulation of the lactase-persistence trait in multiple human populations through convergent evolutionary pathways.<\/p>\n<div class=\"textbox\">\n<h2 class=\"import-Normal\">Special Topic: Skin Tone Genetic Regulation<\/h2>\n<p class=\"import-Normal\">The melanocortin 1 receptor (<em>MC1R<\/em>) gene acts to control which types of melanin (eumelanin or pheomelanin) are produced by melanocytes. The <em>MC1R<\/em> receptor is located on the surface of the melanocyte cells (Quillen Et al. 2018). Activation of the <em>MC1R <\/em>receptors may occur through exposure to specific environmental stimuli or due to underlying genetic processes. Inactive or blocked <em>MC1R <\/em>receptors result in melanocytes producing pheomelanin. If the <em>MC1R<\/em> gene receptors are activated, then the melanocytes will produce eumelanin. Thus, individuals with activated <em>MC1R<\/em> receptors tend to have darker-pigmented skin and hair than individuals with inactive or blocked receptors.<\/p>\n<p class=\"import-Normal\">The alleles of another gene, the major facilitator, superfamily domain-containing protein 12 (<em>MFSD12<\/em>) gene, affect the expression of melanocytes in a different way than the <em>MC1R<\/em> gene. Instead of affecting the activation of melanocyte receptors, the <em>MFSD12<\/em> alleles indirectly affect the membranes of melanocyte lysosomes (Quillen Et al. 2018). The melanocyte\u2019s lysosomes are organelles containing digestive enzymes, which ultimately correlate to varying degrees of pigmentation in humans. Variations in the membranes of the melanocyte lysosomes ultimately correlate to differing degrees of pigmentation in humans.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Ancestral <em>MFSD12 <\/em>allele variants are present in European and East Asian populations and are associated with lighter pigmentation of the skin (Crawford Et al. 2017; Quillen Et al. 2018). In addition, this ancestral variant is also associated with Tanzanian, San, and Ethiopian populations of Afro-Asiatic ancestry (Crawford Et al. 2017; Quillen Et al. 2018). In contrast, the more derived (i.e., more recent) allele variants that are linked to darker skin tones are more commonly present in East African populations, particularly those of Nilo-Saharan descent (Crawford Et al. 2017; Quillen Et al. 2018). The notion that ancestral alleles of <em>MFSD12<\/em> are associated with lighter skin pigmentation is in opposition to the commonly accepted idea that our pigmentation was likely darker throughout early human evolution (Crawford Et al. 2017; Quillen Et al. 2018). Due to the complexity of the human genome, <em>MFSD12<\/em> and <em>MC1R <\/em>are but two examples of alleles affecting human skin tone. Furthermore, there is genetic evidence suggesting that certain genomic variants associated with both darker and lighter skin colour have been subject to directional selection processes for as long as 600,000 years, which far exceeds the evolutionary span of <em>Homo sapiens sapiens<\/em> (Crawford Et al. 2017; Quillen Et al. 2018).<\/p>\n<\/div>\n<\/div>\n<div class=\"__UNKNOWN__\">\n<div class=\"textbox shaded\">\n<h2>Summary<\/h2>\n<p>From the time that the first of our species left Africa, we have had to adjust and adapt to numerous environmental challenges. The remarkable ability of human beings to maintain homeostasis through a combination of both nongenetic (adjustments) and genetic (adaptations) means has allowed us to occupy a remarkable variety of environments, from high-altitude mountainous regions to the tropics near the equator. From adding piquant, pungent spices to our foods as a means of inhibiting food-borne illnesses due to bacterial growth to donning garments specially suited to local climates, behavioural adjustments have provided us with a nongenetic means of coping with obstacles to our health and well-being. Acclimatory adjustments, such as sweating when we are warm in an attempt to regulate our body temperature or experiencing increased breathing rates as a means of increasing blood oxygen levels in regions where the partial pressure of oxygen is low, have been instrumental in our survival with respect to thermal and altitudinal environmental challenges. For some individuals, developmental adjustments that were acquired during their development and growth phases (e.g., increased heart and lung capacities for individuals from high-altitude regions) provide them with a form of physiological advantage not possible for someone who ventures to such an environmentally challenging region as an adult. Genetically mediated adaptations, such as variations in the pigmentation of our skin, have ensured our evolutionary fitness across all latitudes. Taken together, these examples point to a broader question: will the human species continue to adjust and adapt to new environmental challenges in the future? If past performance is any measure of future expectations, then the human story will continue as long as we do not alter our environment to the point that the plasticity of our behaviour, physiological, and morphological boundaries is exceeded.<\/p>\n<h2 class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Review Questions<\/h2>\n<ul>\n<li class=\"import-Normal\" style=\"text-indent: 0pt\">Detail at least two examples of how natural selection has influenced human variation. Specifically, what was the selective pressure that may have led to a preference for a specific trait and how is that trait related to an increased level of fitness?<\/li>\n<li class=\"import-Normal\" style=\"text-indent: 0pt\">Why is reduced pigmentation of the skin advantageous for individuals from northern latitudes? What role does darker skin pigmentation serve for individuals near the equator? What is the relationship between skin pigmentation and fitness?<\/li>\n<li class=\"import-Normal\" style=\"text-indent: 0pt\">What are some of the risks associated with pregnancy at high altitude? Compare and contrast the various genetic mutations of the indigenous Tibetan and Ethiopian high-altitude populations. In your answer, specifically address the issue of pregnancy at high altitudes.<\/li>\n<li class=\"import-Normal\" style=\"text-indent: 0pt\">What is the relationship between the sickle cell mutation and the <em>Plasmodium<\/em> parasite? Would having the HbSA genotype still be advantageous in a region where such parasites are not common? Why or why not?<\/li>\n<\/ul>\n<\/div>\n<p>&nbsp;<\/p>\n<h2 class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Key Terms<strong><br \/>\n<\/strong><\/h2>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Acclimatory adjustm<\/strong><strong>ents<\/strong>: Processes by which an individual organism adjusts in order to maintain homeostasis in response to environmental challenges.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Activated melanogenesis<\/strong>: Increase in melanin production in response to ultraviolet radiation (UV) exposure.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Adaptation<\/strong>: Alteration in population-level gene frequencies related to environmentally induced selective pressures; leads to a greater level of fitness for a population related to a specific environment.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Adjustment<\/strong>: Nongenetic-based ways in which organisms adjust to environmental stressors.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Allen\u2019s Rule<\/strong>: Due to thermal adaptation, homeothermic animals have body volume-to-surface ratios that vary inversely with the average temperature of their environment. In cold climates, the anticipated ratio is high; in warm climates, it is low.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Basal melanogenesis<\/strong>: Genetically mediated, non-environmentally influenced base melanin level.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Behavioural adjustments<\/strong>: An individual\u2019s culturally mediated responses to an environmental stressor in an effort to maintain homeostasis.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Bergmann\u2019s Rule<\/strong>: For a broadly distributed monophyletic group, species and populations of smaller size tend to be found in environments with warmer climates and those of larger size tend to be found in ones that are colder.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Cline<\/strong>: A continuum of gradations (i.e., degrees or levels) of a specific trait.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Conduction<\/strong>: Mechanism of heat transfer between objects through direct contact.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Convection<\/strong>: Movement of heat away from a warm object to the cooler surrounding fluid (i.e., gas or liquid).<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Convergent evolution<\/strong>: Evolutionary process whereby organisms that are not closely related independently evolve similar traits as a product of adaptation to similar evolutionary parameters.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Erythrocyte<\/strong>: Red blood cell; most common form of blood cell; the principle means of transporting oxygen throughout the circulatory system.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Evaporation<\/strong>: Mechanism of heat transfer whereby liquid is transformed into a gas, utilizing energy (e.g., heat).<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Folic acid<\/strong>: Form of B complex vitamin necessary for proper fetal development.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Gloger\u2019s Rule<\/strong>: For mammals of the same species, those with more darkly pigmented forms tend to be found closer to the equator and those with lighter forms are found in regions further from the equator.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Homeostasis<\/strong>: Condition of optimal functioning for an organism.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Hyperpnea<\/strong>: Increased depth and rate of respiration.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Hypothalamus<\/strong>: Small portion of the human brain responsible for body temperature regulation.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Lactase persistence<\/strong>: Genetic mutation permitting the continued production of lactase-phlorizin hydrolase enzyme in the small intestine past the weaning period.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Melanin<\/strong>: Black-brown pigment produced by melanocytes; one of the primary pigments in skin.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Melanocytes<\/strong>: Specialized cells that produce melanin.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Phenotypic plasticity<\/strong>: Ability of one genotype to produce more than one phenotype dependent on environmental conditions.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Radiation<\/strong>: Mechanism of heat transfer involving electromagnetic energy being emitted from an object.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Sickle cell disease<\/strong>: A group of genetically inherited blood disorders characterized by an abnormality in the shape of the hemoglobin within erythrocytes (red blood cells).<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Stressor<\/strong>: Any stimulus resulting in an imbalance in an organism\u2019s homeostatic balance.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Vasoconstriction<\/strong>: Narrowing of the blood vessels due to contractions of the muscular vessel walls.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Vasodilation<\/strong>: Dilation of the blood vessels due to relaxation of the muscular vessel walls.<\/p>\n<h2 class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">For Further Exploration<strong><br \/>\n<\/strong><\/h2>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Homeostasis<\/strong><\/p>\n<p class=\"import-Normal\">Baptista, Vander. 2006. \u201c<a href=\"https:\/\/doi.org\/10.1152\/advan.00075.2006\" target=\"_blank\" rel=\"noopener\">Starting Physiology: Understanding Homeostasis<\/a>.\u201d <em>Advances in Physiology Education<\/em> 30: 263\u2013264.<\/p>\n<p class=\"import-Normal\">Goldstein, David S., and Bruce McEwen. 2002. \u201c<a href=\"https:\/\/doi.org\/10.1080\/102538902900012345\" target=\"_blank\" rel=\"noopener\">Allostasis, Homeostats, and the Nature of Stress<\/a>.\u201d <em>The International Journal on the Biology of Stress<\/em> 5 (1): 55\u201358.<\/p>\n<p class=\"import-Normal\"><strong>General Clinal Variation and Genetic Exchange<\/strong><\/p>\n<p class=\"import-Normal\">Delhey, Kaspar. 2019. \u201c<a href=\"https:\/\/doi.org\/10.1111\/brv.12503\" target=\"_blank\" rel=\"noopener\">A Review of Gloger&#8217;s Rule, an Ecogeographical Rule of Colour: Definitions, Interpretations and Evidence<\/a>.\u201d <em>Biological Reviews<\/em> 94 (4): 1294\u20131316.<\/p>\n<p class=\"import-Normal\">Feng, Yuanqing, Michael A. McQuillan, and Sarah A. Tishkoff. 2021. \u201c<a href=\"https:\/\/doi.org\/10.1093\/hmg\/ddab007\" target=\"_blank\" rel=\"noopener\">Evolutionary Genetics of Skin Pigmentation in African Populations<\/a>.\u201d <em>Human Molecular Genetics<\/em> 30 (R1): R88\u2013R97.<\/p>\n<p class=\"import-Normal\">Hu, Hao, Nayia Petousi, Gustavo Glusman, Yao Yu, Ryan Bohlender, Tsewang Tashi, Jonathan M. Downie, et al. 2017. \u201c<a href=\"https:\/\/doi.org\/10.1371\/journal.pgen.1006675\" target=\"_blank\" rel=\"noopener\">Evolutionary History of Tibetans Inferred from Whole-Genome Sequencing<\/a>.\u201d <em>PLoS Genetics <\/em>13 (4): e1006675. .<\/p>\n<p class=\"import-Normal\">Jablonski, Nina G. 2021. \u201c<a href=\"https:\/\/doi.org\/10.1002\/ajpa.24200\" target=\"_blank\" rel=\"noopener\">Skin Color and Race<\/a>.\u201d Special issue, \u201cRace Reconciled II: Interpreting and Communicating Biological Variation and Race in 2021,\u201d <em>American Journal of Physical Anthropology<\/em> 175 (2): 437\u2013447.<\/p>\n<p class=\"import-Normal\">Pritchard, Jonathan K., Joseph K. Pickrell, and Graham Coop. 2010. \u201c<a href=\"https:\/\/doi.org\/10.1016\/j.cub.2009.11.055\" target=\"_blank\" rel=\"noopener\">The Genetics of Human Adaptation: Hard Sweeps, Soft Sweeps, and Polygenic Adaptation<\/a>.\u201d <em>Current Biology<\/em> 20 (4): R208\u2013R215.<\/p>\n<p class=\"import-Normal\">Sankararaman, Sriram, Swapan Mallick, Nick Patterson, and David Reich. 2016. \u201c<a href=\"https:\/\/doi.org\/10.1016\/j.cub.2016.03.037\" target=\"_blank\" rel=\"noopener\">The Combined Landscape of Denisovan and Neanderthal Ancestry in Present-Day Humans<\/a>.\u201d <em>Current Biology<\/em> 26 (9): 1241\u20131247.<\/p>\n<p class=\"import-Normal\"><strong>Lactase Persistence<\/strong><\/p>\n<p class=\"import-Normal\">HHMI BioInteractive. 2021. \u201c<a href=\"https:\/\/www.biointeractive.org\/classroom-resources\/making-fittest-got-lactase-co-evolution-genes-and-culture\" target=\"_blank\" rel=\"noopener\">The Making of the Fittest: Got Lactase? The Co-evolution of Genes and Culture<\/a>.\u201d Accessed April 7, 2023.<\/p>\n<p class=\"import-Normal\"><strong>Malaria and Sickle Cell Anemia<\/strong><\/p>\n<p class=\"import-Normal\">Bill and Melinda Gates Foundation. 2022. \u201c<a href=\"https:\/\/www.gatesfoundation.org\/our-work\/programs\/global-health\/malaria\" target=\"_blank\" rel=\"noopener\">Malaria<\/a>.\u201d Accessed April 7, 2023.<\/p>\n<p class=\"import-Normal\">Centers for Disease Control and Prevention. 2022. \u201c<a href=\"https:\/\/www.cdc.gov\/parasites\/malaria\/index.html\" target=\"_blank\" rel=\"noopener\">Malaria<\/a>.\u201d Accessed April 7, 2023.<\/p>\n<p class=\"import-Normal\">HHMI BioInteractive. 2020. \u201c<a href=\"https:\/\/www.biointeractive.org\/classroom-resources\/making-fittest-natural-selection-humans\" target=\"_blank\" rel=\"noopener\">The Making of the Fittest: Natural Selection in Humans<\/a>.\u201d 2020. Accessed April 7, 2023.<\/p>\n<p class=\"import-Normal\">National Institutes of Health: National Center for Advancing Translational Sciences. \u201c<a href=\"https:\/\/rarediseases.info.nih.gov\/diseases\/8614\/sickle-cell-anemia\" target=\"_blank\" rel=\"noopener\">Sickle Cell Anemia<\/a>.\u201d Accessed April 7, 2023.<\/p>\n<p class=\"import-Normal\">World Health Organization. 2022. \u201c<a href=\"https:\/\/www.who.int\/news-room\/fact-sheets\/detail\/malaria\" target=\"_blank\" rel=\"noopener\">Malaria<\/a>.\u201d Accessed April 7, 2023.<\/p>\n<p class=\"import-Normal\"><strong>Rickets and Bone Health<\/strong><\/p>\n<p class=\"import-Normal\">National Institutes of Health: National Center for Advancing Translational Sciences. \u201c<a href=\"https:\/\/rarediseases.info.nih.gov\/diseases\/5700\/rickets\" target=\"_blank\" rel=\"noopener\">Rickets<\/a>.\u201d Accessed April 7, 2023.<\/p>\n<p class=\"import-Normal\">Talmadge, D. W., and R. V. Talmadge. 2007. \u201cCalcium Homeostasis: How Bone Solubility Relates to All Aspects of Bone Physiology.\u201d <em>Journal of Musculoskeletal and Neuronal Interactions <\/em>7 (2): 108\u2013112.<\/p>\n<p class=\"import-Normal\"><strong>Skin Colour<\/strong><\/p>\n<p class=\"import-Normal\">HHMI BioInteractive. 2020. \u201c<a href=\"https:\/\/www.biointeractive.org\/classroom-resources\/biology-skin-color\" target=\"_blank\" rel=\"noopener\">The Biology of Skin Color<\/a>.\u201d Accessed April 7, 2023<\/p>\n<h2 class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">References<\/h2>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">American Academy of Pediatrics, Task Force on Infant Sleep Position and Sudden Infant Death Syndrome. 2000. \u201cChanging Concepts of Sudden Infant Death Syndrome: Implications for Infant Sleeping Environment and Sleep Position.\u201d <em>Pediatrics<\/em> 105 (3): 650\u2013656.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Beja-Pereira, Albano, David Caramelli, Carles Lalueza-Fox, Cristiano Vernesi, Nuno Ferrand, Antonella Casoli, Felix Goyache, et al. 2006. \u201cThe Origin of European Cattle: Evidence from Modern and Ancient DNA.\u201d <em>PNAS <\/em>103 (21): 8113\u20138118.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Best, Andre, Daniel E. Lieberman, and Jason M. Kamilar. 2019. \u201cDiversity and Evolution of Human Eccrine Sweat Gland Density.\u201d <em>Journal of Thermal Biology<\/em> 84: 331\u2013338.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Bigham, Abigail W. 2016. \u201c<a href=\"https:\/\/www.cdc.gov\/ncbddd\/sicklecell\/data.html\" target=\"_blank\" rel=\"noopener\">Genetics of Human Origin and Evolution: High-Altitude Adaptations<\/a>.\u201d <em>Current Opinion in Genetics &amp; Development<\/em> 41: 8\u201313.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Centers for Disease Control and Prevention. 2017. \u201cData &amp; Statistics on Sickle Cell Disease.\u201d <em>Centers for Disease Control and Prevention<\/em> website, August 9. Accessed April 7, 2023. .<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Crawford, Nicholas G., Derek E. Kelly, Matthew E. B. Hansen, Marcia H. Beltrame, Shaohua Fan, Shanna L. Bowman, Ethan Jewett, et al. 2017. \u201cLoci Associated with Skin Pigmentation Identified in African Populations.\u201d <em>Science<\/em> 358 (6365): 1\u201349.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Cyrkalff, Marek, Cecilia P. Sanchez, Nicole Kilian, Curille Bisseye, Jacques Simpore, Friedrich Frischknecht, and Michael Lanzer. 2011. \u201cHemoglobins S and C Interfere with Actin Remodeling in <em>Plasmodium <\/em><em>falciparum<\/em>-Infected Erythrocytes.\u201d <em>Science<\/em> 334 (6060): 1283\u20131286.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Dzialanski, Zbigniew, Michael Barany, Peter Engfeldt, Anders Magnuson, Lovisa A. Olsson, and Torbj\u04e7rn K. Nilsson. 2016. \u201cLactase Persistence versus Lactose Intolerance: Is There an Intermediate Phenotype?\u201d <em>Clinical Biochemistry<\/em> 49 (2016): 248\u2013252.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Fernando, Sumadya D., Chaturaka Rodrigo, and Senaka Rajapakse. 2010. \u201cThe \u2018Hidden\u2019 Burden of Malaria: Cognitive Impairment Following Infection.\u201d <em>Malaria Journal<\/em> 9 (366): 1\u201311.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Gerbault, Pascale, Anke Liebert, Yuval Itan, Adam Powell, Mathias Currat, Joachim Burger, Dallas M. Swallow, and Mark G. Thomas. 2011. \u201cEvolution of Lactase Persistence: An Example of Human Niche Construction.\u201d <em>Philosophical Transactions of the Royal Society B: Biological Sciences <\/em>366 (1566): 863\u2013877.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Gray, Olivia A., Jennifer Yoo, D\u00e9bora R. Sobriera, Jordan Jousma, David Witnosky, Noboru J. Sakabe, Ying-Jie Ping, et al. 2022. \u201cA Pleiotropic Hypoxia-Sensitive <em>EPAS1<\/em> Enhancer Is Disrupted by Adaptive Alleles in Tibetans.\u201d <em>Science Advances <\/em>8 (47): 1\u201313.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Hartman, T. K., S. J. Rogerson, and P. R. Fischer. 2013. \u201cThe Impact of Maternal Malaria on Newborns.\u201d <em>Annals of Tropical Paediatrics<\/em> 30 (4): 271\u2013282.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Longo, Dan L., Fr\u00e9d\u00e9ric B. Piel, Martin H. Steinberg, and David C. Rees. 2017. \u201cSickle Cell Disease.\u201d <em>The New England Journal of Medicine<\/em> 376 (16): 1561\u20131573.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Maddux, Scott D., Todd R. Yokley, Bohumil M. Svoma, and Robert G. Franciscus. 2016. \u201cAbsolute Humidity and the Human Nose: A Reanalysis of Climate Zones and Their Influence on Nasal Form and Function.\u201d <em>American Journal of Physical Anthropology <\/em>161 (2): 309\u2013320.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Meyer, M. C., M. S. Alexander, Z. Wang, D. L. Hoffmann, J. A. Dahl, D. Degering, W. R. Haas, and F. Schl\u00fctz. 2017. \u201cPermanent Human Occupation of the Central Tibetan Plateau in the Early Holocene.\u201d <em>Science <\/em>355 (6320): 64\u201367.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Moore, Lorna G., Susan Niermeyer, and Stacy Zamudio. 1998. \u201cHuman Adaptation to High Altitude: Regional and Life-Cycle Perspectives.\u201d <em>Yearbook of Physical Anthropology<\/em> 41: 25\u201364.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Noback, Marlijn L., Katerina Harvati, and Fred Spoor. 2011. \u201cClimate-Related Variation of the Human Nasal Cavity.\u201d <em>American Journal of Physical Anthropology<\/em> 145 (4): 599\u2013614.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Peacock, A. J. 1998. \u201cABC of Oxygen: Oxygen at High Altitude.\u201d <em>BMJ<\/em> 317 (7165): 1063\u20131066.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Pontzer, Herman, Mary H. Brown, Brian M. Wood, David A. Raichlen, Audax Z.P. Madbulla, Jacob A. Harris, Holly Dunsworth, et al. 2021. \u201cEvolution of Water Conservation in Humans.\u201d <em>Current Biology<\/em> 31 (8): 1804\u20131810.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Quillen, Ellen E., Heather L. Norton, Esteban J. Parra, Frida Loza-Durazo, Khai C. Ang, Florin Mircea Illiescu, Laurel N. Pearson, et al. 2019. \u201cShades of Complexity: New Perspectives on the Evolution and Genetic Architecture of Human Skin.\u201d <em>Yearbook<\/em><em> of Physical Anthropology <\/em>168 (S67): 4\u201326.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Ranciaro, Alessia, Michael C. Campbell, Jibril B. Hirbo, Wen-Ya Ko, Alain Froment,<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Paolo Anagnostou, Maritha J. Kotze, et al. 2014. \u201cGenetic Origins of Lactase Persistence and the Spread of Pastoralism in Africa.\u201d <em>American Journal of Human Genetics <\/em>94 (4): 496\u2013510.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Roby, Brianne Barnett, Marsha Finkelstein, Robert J. Tibesar, and James D. Sidman. 2012. \u201cPrevalence of Positional Plagiocephaly in Teens Born after the \u2018Back to Sleep\u2019 Campaign.\u201d <em>Otolaryn<\/em><em>g<\/em><em>ology<\/em><em>\u2014Head and Neck Surgery<\/em> 146 (5): 823\u2013828.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Sherman, Paul W., and Jennifer Billing. 1999. \u201cDarwinian Gastronomy: Why We Use Spices.\u201d <em>BioScience <\/em>49 (6): 453\u2013463.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Tishkoff, Sarah A., Floyd A. Reed, Alessia Ranciaro, Benjamin F. Voight, Courtney C. Babbitt, Jesse S. Silverman, Kweli Powell, et al. 2007. \u201cConvergent Adaptation of Human Lactase Persistence in Africa and Europe.\u201d <em>Nature Genetics<\/em> 39 (1): 31\u201340.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">World Health Organization. 2021. \u201c<a href=\"https:\/\/www.who.int\/teams\/global-malaria-programme\/reports\/world-malaria-report-2021\" target=\"_blank\" rel=\"noopener\">World Malaria Report 2021<\/a>.\u201d <em>World Health Organization<\/em> website, December 4, 2022. Accessed April 7, 2023.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Zhang, Xinjun, Kelsey E. Witt, Mayra M. Ba\u00f1uelos, Amy Ko, Kai Yuan, Shuhua Xu, Rasmus Nielsen, and Emilia Huerta-Sanchez. 2021. \u201cThe History and Evolution of Denisovan-<em>EPAS1<\/em> Haplotype in Tibetans.\u201d <em>PNAS Biological Sciences<\/em> 118 (22): 1\u20139.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">\n<\/div>\n<\/div>\n<div class=\"glossary\"><span class=\"screen-reader-text\" id=\"definition\">definition<\/span><template id=\"term_1695_1840\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1695_1840\"><div tabindex=\"-1\"><h2>Introductory Statement<\/h2>\n<p>This preliminary section offers an overview of the discipline of Anthropology. Students who have previously completed an introductory course (such as ANTH 202 or its equivalent) will likely find the material familiar. Although reviewing this section is recommended, those confident in their understanding of Anthropology and its four subdisciplines may choose to proceed directly to <a href=\"https:\/\/opentextbooks.concordia.ca\/explorationsversiontwo\/chapter\/1\/\">Chapter 1<\/a>. It is important to note that this textbook reflects an American approach to organizing the discipline; in other academic traditions, anthropological knowledge may be divided into different disciplinary frameworks.<\/p>\n<header class=\"textbox__header\">\n<h2 class=\"textbox__title\">Learning Objectives<\/h2>\n<p>&nbsp;<\/p>\n<\/header>\n<div class=\"textbox__content\">\n<ul>\n<li class=\"import-Normal\">Describe anthropology and the four subdisciplines.<\/li>\n<li class=\"import-Normal\">Explain the main anthropological approaches.<\/li>\n<li class=\"import-Normal\">Define biological anthropology, describe its key questions, and identify major subfields<\/li>\n<\/ul>\n<p class=\"import-Normal\">Diving in caves along the Caribbean coast of Mexico, archaeologist Octavio del Rio and his team spotted something unusual in the sand 26 feet below the ocean surface. As they swam closer, they suspected it could be a bone\u2014and likely a very ancient one, as this cave system is inaccessible today without modern diving equipment. However, in the distant past, these caves were dry land formations high above the ocean. The divers ended up recovering not just one but many bones from the site. Eventually they were able to reconstruct an 80% complete human skeleton that they named \u201cEve of Naharon.\u201d Dated to 13,600 years ago, she is (as of today) the oldest known North American skeleton (TANN 2018).<\/p>\n<p class=\"import-Normal\">Who was Eve? What was her life like? How did she end up in the cave? What can we learn about her from the bones she left behind? Anthropologists have determined that Eve was 4.6 feet tall, had a broken back, and died in her early 20s. Although it is rare to find an ancient, nearly complete skeleton in the ocean depths, Eve is not the only such find. In underwater caves along Mexico\u2019s Yucatan Peninsula, archaeologists have found eight well-preserved skeletons dated between 9,000 to 13,000 years old. With each new discovery\u2014whether it is a skeleton in North America, fossil footprints in Tanzania, or a mandible with teeth in China\u2014we come another step closer to understanding the evolution of our species.<\/p>\n<p class=\"import-Normal\">Biological anthropologists study when and how human beings evolved; their intriguing findings are the focus of this book. Biological anthropology is one of four <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1087\">subdisciplines<\/a><\/strong>\u00a0within anthropology; the others are cultural anthropology, archaeology, and linguistic anthropology. All anthropological subdisciplines seek to better understand what it means to be human.<\/p>\n<h2 class=\"import-Normal\">What is Anthropology?<\/h2>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Why are people so diverse (Figure 1.1)? Some people live in the frigid Arctic tundra, others in the arid deserts of sub-Saharan Africa, and still others in the dense forests of Papua New Guinea. Human beings speak more than 6,000 distinct languages. Some people are barely five feet tall while others stoop to fit through a standard door frame. What makes people, around the world, look, speak, and behave differently from one another? And what do all humans share in common?<\/p>\n<figure style=\"width: 392px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2023\/02\/image9.png\" alt=\"Four people with different phenotypes\/features from throughout the world.\" width=\"392\" height=\"259\" \/><figcaption class=\"wp-caption-text\">Figure 1.1: Despite superficial differences among individuals, humans are 99.9% genetically similar to one another. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-2\/\" target=\"_blank\">Humans (Figure 1.1)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\" target=\"_blank\">CC BY-NC-SA 4.0 License<\/a>. [Includes <a href=\"https:\/\/www.flickr.com\/photos\/minusma\/33644830088\/in\/album-72157707941932464\/\" target=\"_blank\">Untitled<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/minusma\/\" target=\"_blank\">Mission de I\u2019ONU au Mali - UN Mission in Mali<\/a>\/Gema Cortes, <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\" target=\"_blank\">CC BY-NC-SA 2.0<\/a>; <a href=\"https:\/\/www.flickr.com\/photos\/fischerfotos\/25315353063\" target=\"_blank\">Untitled in Middle East<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/fischerfotos\/\" target=\"_blank\">Mark Fischer<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/\" target=\"_blank\">CC-BY-SA 2.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Smiling_Blonde_Girl.jpg\" target=\"_blank\">Smiling Blonde Girl<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/23992271@N04\" target=\"_blank\">Egor Gribanov<\/a>,<a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\" target=\"_blank\"> CC BY 2.0<\/a>; <a href=\"https:\/\/www.flickr.com\/photos\/un_photo\/5881472981\" target=\"_blank\">UNDP Supports Mongolian Herders<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/un_photo\/\" target=\"_blank\">United Nations Photo<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-nd\/2.0\/\" target=\"_blank\">CC BY-NC-ND].<\/a><\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Anthropology is a discipline that explores human differences and similarities by investigating our biological and cultural complexity, past and present. Derived from Greek, the word -<em>anthropos<\/em> means \u201chuman\u201d and -<em>logy<\/em> refers to the \u201cstudy of.\u201d Therefore, anthropology is, by definition, the study of humans. Anthropologists are not the only scholars to focus on the human condition; biologists, sociologists, psychologists, and others also examine human nature and societies. However, anthropology is a uniquely dynamic, multifaceted discipline that emerged from a deep-seated curiosity about who we are as a species.<\/p>\n<h2 class=\"import-Normal\">The Subdisciplines<\/h2>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">In the United States, the discipline of anthropology includes four subdisciplines: cultural anthropology, biological anthropology, archaeology, and linguistic anthropology. In addition, applied anthropology is sometimes called the fifth subdiscipline (Figure 1.2). Each of the subdisciplines provides a distinct perspective on the human experience. Some (like biological anthropology) use the scientific method to develop theories about human origins, evolution, material remains, or behaviours. Others (like cultural anthropology) use humanistic and interpretive approaches to understand human beliefs, languages, behaviours, cultures, and societies. Findings from all subdisciplines, together, contribute to a multifaceted appreciation of human biocultural experiences, past and present.<\/p>\n<h3 class=\"import-Normal\"><strong>Cultural Anthropology<\/strong><\/h3>\n<figure style=\"width: 376px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image7.png\" alt=\"The word \u201cAnthropology\u201d is depicted as an umbrella as it hovers over text boxes representing the subdisciplines.\" width=\"376\" height=\"280\" \/><figcaption class=\"wp-caption-text\">Figure 1.2: The discipline of anthropology has four subdisciplines: archaeology, cultural anthropology, biological anthropology, and linguistic anthropology, as well as an applied dimension. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-2\/\" target=\"_blank\">Subdisciplines of anthropology (Figure 1.8)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by <a href=\"https:\/\/marynelsonstudio.com\" target=\"_blank\">Mary Nelson<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Cultural anthropologists focus on similarities and differences among living persons and societies. They suspend their sense of what is expected in their own culture in order to understand other perspectives without judging them (<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1088\">cultural relativism<\/a><\/strong>). They learn these perspectives through <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1089\">participant-observation<\/a><\/strong> fieldwork. Beyond describing another way of life, cultural anthropologists ask broader questions about humankind: Are human emotions universal or culturally distinct? Is maternal behaviour learned or innate? How and why do groups migrate to new places? For cultural anthropologists, no aspect of human life is outside their purview: They study art, religion, medicine, migration, natural disasters, even video gaming. While many cultural anthropologists are intrigued by human diversity, they recognize that people around the world share much in common.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">One famous U.S. cultural anthropologist, Margaret Mead (1901\u20131978, Figure 1.3), conducted cross-cultural studies of gender and socialization. In the early twentieth century, people in the U.S. wondered if the emotional turbulence exhibited by American adolescents was caused by the biology of puberty, and thus natural and universal. To find out, Mead went to the Samoan Islands, where she lived for several months getting to know Samoan teenagers. She learned that Samoan adolescence was relatively tranquil and happy. Based on her fieldwork, Mead wrote <em>Coming of Age in Samoa<\/em>, a best-selling book that was both sensational and scandalous (Mead 1928). In it, she critiqued U.S. parenting as restrictive in contrast to Samoan parenting, which allowed teenagers to freely explore their community and even their sexuality. Ultimately, she argued that nurture (i.e., socialization) more than nature (i.e., biology) shaped adolescent development. Despite her expressed relativism, she has been critiqued recently for exploiting the people she studied.<\/p>\n<div class=\"__UNKNOWN__\">\n<figure style=\"width: 217px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image11.jpg\" alt=\"Historic photo of a middle-aged woman in dark blouse.\" width=\"217\" height=\"266\" \/><figcaption class=\"wp-caption-text\">Figure 1.3: Margaret Mead, circa 1948. Credit: <a href=\"https:\/\/www.flickr.com\/photos\/internetarchivebookimages\/20388587586\/\" target=\"_blank\">Margaret Mead<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/internetarchivebookimages\/\" target=\"_blank\">Internet Archive Book Images<\/a> has been designated to the <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/cc0\/\" target=\"_blank\">public domain (CC0)<\/a>. [Image from page 47 of \"A brief expedition into science at the American Museum of Natural History\" (1969).]<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Cultural anthropologists do not always travel far to learn about human experiences. In the 1980s, American anthropologist Philippe Bourgois (1956\u2013) asked how pockets of extreme poverty persist in the United States, a country widely perceived as wealthy with an overall high quality of life compared to other countries. To answer this question, he lived with Puerto Rican drug dealers in East Harlem, contextualizing their experiences both historically and presently, in terms of ongoing social marginalization and institutional racism. Rather than blame drug dealers for their choices, Bourgois argued that both individual choices and social inequality can trap people in the overlapping worlds of drugs and poverty (Bourgois 2003).<\/p>\n<h3 class=\"import-Normal\"><strong>Linguistic <\/strong><strong>A<\/strong><strong>nthropology<\/strong><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The study of people is incomplete without attending to language, a defining trait of human beings. While other animals have communication systems, only humans have complex symbolic languages\u2014and more than 6,000 of them! Human language makes it possible to teach and learn, plan and think abstractly, coordinate our efforts, and contemplate our own demise. Linguistic anthropologists ask questions like: How did language first emerge? How has it evolved and diversified over time? How has language helped our species? How can linguistic style convey social identity? How does language influence our worldview? Some linguistic anthropologists track the emergence and diversification of languages, while others focus on language use in social context. Still others explore how language is crucial to socialization: children learn their culture and identities through language and nonverbal forms of communication (Ochs and Schieffelin 2017; Figure 1.4).<\/p>\n<figure style=\"width: 302px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image14.png\" alt=\"Photo of mother and daughter speaking to a newborn baby.\" width=\"302\" height=\"233\" \/><figcaption class=\"wp-caption-text\">Figure 1.4: From the moment they are born, children learn through language and nonverbal forms of communication. Credit: <a href=\"https:\/\/www.flickr.com\/photos\/torbein\/49278674\/\" target=\"_blank\">Babytalk<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/torbein\/\" target=\"_blank\">Torbein R\u00f8nning<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-nd\/2.0\/\" target=\"_blank\">CC BY-NC-ND 2.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">One line of linguistic anthropological research focuses on the relationships among language, thought, and culture. For example, Benjamin Whorf (1897\u20131941) observed that whereas the English language has grammatical tenses to indicate past, present, and future, the Hopi language does not; instead, it indicates whether or not something has \u201cmanifested.\u201d Whorf argued that this grammatical difference causes English and Hopi speakers to think about time in distinct ways: English speakers think about time in a linear way, while Hopi think about time in terms of a cycle of things or events that have manifested or are manifesting (Whorf 1956). Based on his research, Whorf developed a strong version of the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1090\">Sapir-Whorf hypothesis<\/a> <\/strong>(also known as linguistic relativity), which states that language shapes thought. Some critics, like German American linguist Ekkehart Malotki (1938\u2013), recognized that English and Hopi tenses differ but argued against Whorf by claiming that the Hopi language does, in fact, have linguistic terms for time and that a linear sense of time may be universal (Malotki 1983). Nevertheless, anthropological linguists tend to see human languages as a unique form of communication, linked to our ability to think and process our world.<\/p>\n<h3 class=\"import-Normal\"><strong>Archaeology<\/strong><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Archaeologists focus on material remains\u2014tools, pottery, rock art, shelters, seeds, bones, and other objects\u2014to better understand people and societies. Archaeologists ask specific questions like: How did people in a particular area live? How did they utilize their environment? What happened to their society? They also ask general questions about humankind: When did our ancestors begin to walk on two legs? How and why did they leave Africa? Why did humans first develop agriculture? How did the first cities develop?<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">One critical method that archaeologists use to answer these questions is excavation, which involves carefully digging and removing sediment to uncover material remains while recording their context. Take the example of Kathleen Kenyon (1906\u20131978), a British archaeologist and one of few female archaeologists in the 1940s. While excavating at Jericho, which dates back to 10,000 BCE (Figure 1.5), she discovered city structures and cemeteries built during the Early Bronze Age (3,200 YBP in Europe). Based on her findings, she argued that Jericho is the oldest city continuously occupied by different groups of people for thousands of years (Kenyon 1979).<\/p>\n<figure style=\"width: 424px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image12.png\" alt=\"An archaeological site with excavated structures in front of dry hills.\" width=\"424\" height=\"318\" \/><figcaption class=\"wp-caption-text\">Figure 1.5: Archaeologists, including Kathleen Kenyon, have helped unearth the foundations of ancient dwellings at Jericho. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Jerycho8.jpg\" target=\"_blank\">Jerycho8<\/a> by Abraham Sobkowski has been designated to the <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/cc0\/\" target=\"_blank\">public domain (CC0)<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">While most archaeologists study the past, some excavate at contemporary sites to gain new perspectives on present-day societies. For example, participants in the Garbage Project, which began in the 1970s in Tucson, Arizona, excavate modern landfills as if they were a conventional dig site. They have found that what people say they throw out differs from what is actually in the trash. The landfill holds large amounts of paper products (that people claim to recycle) as well as construction debris (Rathje and Murphy 1992). This finding indicates the need to create more environmentally conscious waste-disposal practices.<\/p>\n<h3 class=\"import-Normal\"><strong>Biological Anthropology<\/strong><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Biological anthropology\u2014the focus of this book\u2014is the study of human evolution and biological variation. Some biological anthropologists study our closest living relatives\u2014monkeys and apes\u2014to learn how nonhuman and human primates are alike and how they differ both biologically and behaviourally (Figure 1.6). Other biological anthropologists focus on extinct human species and subspecies, asking questions like: What did they look like? What did they eat? When did they start to speak? How did they adapt to new environments? Still other biological anthropologists focus on modern human diversity, asking questions about the evolution of traits, like lactose tolerance or skin colour, that differ between populations. Throughout this book, we will learn about biological anthropological research that explores our nonhuman primate cousins, the origins of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1091\">hominins<\/a><\/strong>\u00a0(i.e. humans and fossil human relatives), how they adapted over time, and how we \u2013 modern humans \u2013 continue to change.<\/p>\n<figure style=\"width: 270px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image16.png\" alt=\"A group of chimpanzees in close proximity resting or grooming each other.\" width=\"270\" height=\"199\" \/><figcaption class=\"wp-caption-text\">Figure 1.6: Chimpanzees are the nonhuman primate that is most closely related to humans. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Chimpanzees.jpg\" target=\"_blank\">Chimpanzees<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/12191709@N00\" target=\"_blank\">Klaus Post<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/legalcode\" target=\"_blank\">CC BY 2.0 License<\/a>.<\/figcaption><\/figure>\n<h3 class=\"import-Normal\"><strong>Applied Anthropology<\/strong><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Sometimes considered the fifth subdiscipline, applied anthropology involves the practical application of anthropological theories, methods, and findings to solve real-world problems. Applied anthropologists span the subdisciplines. An applied archaeologist might work in cultural resource management to assess a potentially significant archaeological site unearthed during a construction project. An applied cultural anthropologist could work for a technology company that seeks to understand how people interact with their products in order to design them better. Applied anthropologists are employed outside of academic settings, in public and private sectors, including business firms, advertising companies, city government, law enforcement, hospitals, nongovernmental organizations, and even the military.<\/p>\n<figure style=\"width: 228px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image5.png\" alt=\"Doctor takes notes sitting next to a woman and a sick toddler.\" width=\"228\" height=\"194\" \/><figcaption class=\"wp-caption-text\">Figure 1.7: Paul Farmer in Haiti. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:PEF-with-mom-and-baby---Quy-Ton-12-2003_1-1-310.jpg\" target=\"_blank\">PEF-with-mom-and-baby---Quy-Ton-12-2003 1-1-310<\/a> by Cjmadson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/3.0\/deed.en\" target=\"_blank\">CC BY 3.0 License<\/a>.<\/figcaption><\/figure>\n<p>Trained as both a physician and anthropologist, Paul Farmer (1959\u20132022, Figure 1.7) demonstrated the potential of applied anthropology to improve lives. As a college student in North Carolina, Farmer became interested in the Haitian migrants working on nearby farms. This led him to visit Haiti, the most resource-poor country in the Western Hemisphere, where he was struck by the deprived state of its health care facilities. Years later, he would return to Haiti, as a physician, to treat diseases that had been largely eradicated in the United States, such as tuberculosis and cholera. Drawing on his anthropological training, he also did fieldwork and wrote books that contextualize the suffering of Haitians in relation to historical, social, and political conditions (Farmer 2006). Finally, as an applied anthropologist, he took action by co-founding Partners in Health, a nonprofit organization that establishes health clinics in resource-poor countries and trains local staff to administer care.<\/p>\n<h2 class=\"import-Normal\">Anthropological Approaches<\/h2>\n<p class=\"import-Normal\">Each of the four main anthropological subdisciplines contributes to our understanding of humankind by exploring cultures, languages, material remains, and biological adaptations. To study these phenomena, anthropologists draw upon distinct research approaches, including <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1156\">holism<\/a><\/strong>, comparison, dynamism, and fieldwork.<\/p>\n<h3 class=\"import-Normal\"><strong>Holism<\/strong><\/h3>\n<p class=\"import-Normal\">Anthropologists are interested in the <em>whole <\/em>of humanity. We look at the interactions among several aspects of our complex bodies or societies, rather than focusing on a singular aspect (Figure 1.8). For example, a biological anthropologist studying the social behaviours of a monkey species in South America may not only observe how they interact with one another, but also how physical adaptations, foraging patterns, ecological conditions, and habitat changes also affect their behaviours. By focusing on only one factor, the anthropologist would attain an incomplete understanding of the species\u2019 social life. A cultural anthropologist studying marriage in a small village in India would not only consider local gender norms but also family networks, laws regarding marriage, religious rules, and economic factors. All of these aspects can influence marital practices in a given context. In both examples, the anthropologist is using a holistic approach by considering the multiple interrelated and intersecting factors that comprise a given phenomena.<\/p>\n<figure style=\"width: 292px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image2.png\" alt=\"Silhouette of a person with a web of dotted lines representing elements of humanity.\" width=\"292\" height=\"393\" \/><figcaption class=\"wp-caption-text\">Figure 1.8: By using a holistic approach, anthropologists learn how different aspects of humanity interact with and influence one another. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-2\/\" target=\"_blank\">Holism (Figure 1.2)<\/a>\u00a0original to <a href=\"https:\/\/explorations.americananthro.org\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<h3 class=\"import-Normal\"><strong>Comparison<\/strong><\/h3>\n<p class=\"import-Normal\">Anthropologists use comparative approaches to compare and contrast data from different populations, from groups within a population, or from the same group over time. For example: How do humans today differ from prior <em>Homo sapiens <\/em>populations? How does Egyptian society today compare to ancient Egyptian society? How do male and female behaviours differ within a given human society or a particular primate group? Comparative analyses help us understand commonalities and differences within or across species, groups, or time.<\/p>\n<h3 class=\"import-Normal\"><strong>Dynamism<\/strong><\/h3>\n<p class=\"import-Normal\">Comparative analysis is facilitated by the fact that humans are extremely dynamic. Our ability to change, both biologically and culturally, has enabled us to persist over millions of years and to thrive in different environments. Anthropologists ask about all kinds of changes: short-term and long-term, temporary and permanent, cultural and biological. For example, a cultural anthropologist might look at how people in a relatively isolated society are affected by globalization. A linguistic anthropologist might explore how a hybrid form of language, like Spanglish, emerged. An archaeologist might study how climate change influenced the emergence of agriculture. A biological anthropologist might consider how diseases affecting our ancestors led to physical changes that persist today. All of these examples highlight the dynamic nature of human bodies and societies.<\/p>\n<figure style=\"width: 240px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image23.png\" alt=\"Woman interviewing a student.\" width=\"240\" height=\"158\" \/><figcaption class=\"wp-caption-text\">Figure 1.9: Anthropologist Katie Nelson conducting fieldwork with undocumented Mexican immigrant college students. Credit: Ethnographic interview by Luke Berhow is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<h3 class=\"import-Normal\"><strong>Fieldwork<\/strong><\/h3>\n<p class=\"import-Normal\">Throughout this book, you will read examples of anthropological research from around the world. Anthropologists do not only work in laboratories, libraries, or offices. To collect data, they travel to where their data lives, whether it is a city, village, cave, tropical forest, or desert. At their field sites, anthropologists collect data that, depending on subdiscipline, may include interviews with local peoples (Figure 1.9), examples of language in use, skeletal features, or cultural remains like stone tools. While anthropologists ask an array of questions and use diverse methods to answer their research questions, they share this commitment to conducting research in the field.<\/p>\n<h2 class=\"import-Normal\">What is Biological Anthropology?<\/h2>\n<p class=\"import-Normal\">Biological anthropology uses a scientific and evolutionary approach to answer many of the same questions that all anthropologists are concerned with: What does it mean to be human? Where do we come from? Who are we today? Biological anthropologists are concerned with exploring how humans vary biologically, how humans adapt to their changing environments, and how humans have evolved over time and continue to evolve today. Some biological anthropologists also study what humans and nonhuman primates have in common and how we differ.<\/p>\n<p class=\"import-Normal\">You may have heard biological anthropology referred to by another name\u2014physical anthropology. Physical anthropology is a discipline that dates to as far back as the eighteenth century, when it focused mostly on physical variation among humans. Some early physical anthropologists were also physicians or anatomists interested in comparing and contrasting the human form. These researchers dedicated themselves to measuring bodies and skulls (anthropometry and craniometry) in great detail (Figure 1.10). Many also acted under the misguided racist belief that human biological races existed and that it was possible to differentiate between, or even rank, such races by measuring differences in human anatomy. Anthropologists today agree that there are no biological human races and that all humans alive today are members of the same species, <em>Homo sapiens<\/em>, and subspecies, <em>Homo<\/em> <em>sapiens sapiens<\/em>. We recognize that the differences we can see between peoples\u2019 bodies are due to a wide variety of factors, including environment, diet, activities, and genetic makeup.<\/p>\n<figure style=\"width: 346px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image18.png\" alt=\"A standing person in uniform is using a large metal tool to measure a seated man\u2019s head.\" width=\"346\" height=\"237\" \/><figcaption class=\"wp-caption-text\">Figure 1.10: An anthropometric device used to measure a subject\u2019s head, circa 1913. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Head-Measurer_of_Tremearne_(side_view).jpg\" target=\"_blank\">Head-Measurer of Tremearne (side view)<\/a> by A.J.N. Tremearne, Man 15 (1914): 87\u201388 is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\" target=\"_blank\">public domain<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">The subdiscipline has changed a great deal since these early years. Biological anthropologists no longer identify human differences in order to assign people to groups, like races. The focus is instead on understanding how and why human and primate variation developed through evolutionary processes. The name for the subdiscipline has transitioned in recent years (from <em>physical anthropology<\/em> to <em>biological anthropology<\/em>) to reflect these changes. Many believe the term <em>biological anthropology<\/em> better reflects the subdiscipline\u2019s focus today, which includes genetic and molecular research.<\/p>\n<h3 class=\"import-Normal\"><strong>The Scope of Biological Anthropology<\/strong><\/h3>\n<p class=\"import-Normal\">Just as anthropology as a discipline is wide ranging and holistic, so too is the subdiscipline of biological anthropology. There are at least six <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1092\">subfields<\/a><\/strong>\u00a0within biological anthropology (Figure 1.11): primatology, paleoanthropology, molecular anthropology, bioarchaeology, forensic anthropology, and human biology. Each subfield focuses on a different dimension of what it means to be human from a biological perspective. Through their varied research in these subfields, biological anthropologists try to answer the following key questions:<\/p>\n<ul>\n<li class=\"import-Normal\">What is our place in nature? How are we related to other organisms? What makes us unique?<\/li>\n<li class=\"import-Normal\">What are our origins? What influenced our evolution?<\/li>\n<li class=\"import-Normal\">How and when did we move\/migrate across the globe?<\/li>\n<li class=\"import-Normal\">How are humans around the world today different from and similar to each other? What influences these patterns of variation? What are the patterns of our recent evolution and how do we continue to evolve?<\/li>\n<\/ul>\n<p class=\"import-Normal\">The terms <em>subfield <\/em>and <em>subdiscipline<\/em> are very similar and are often used interchangeably. In this book we use <em>subdiscipline<\/em> to refer to the four major areas of focus that make up the discipline of anthropology: biological anthropology, cultural anthropology, archaeological anthropology, and linguistic anthropology. When we use the term <em>subfield<\/em> we are referring to the different specializations within biological anthropology.<\/p>\n<figure style=\"width: 386px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image13.png\" alt=\"A \u201cbiological anthropology\u201d umbrella hovers over subfield names accompanied by symbols.\" width=\"386\" height=\"365\" \/><figcaption class=\"wp-caption-text\">Figure 1.11: Biological anthropology has at least six subfields. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-2\/\" target=\"_blank\">Subfields of biological anthropology (Figure 1.16)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<h3 class=\"import-Normal\"><strong>Primatology<\/strong><\/h3>\n<p class=\"import-Normal\">Primatologists study the anatomy, behaviour, ecology, and genetics of living and extinct nonhuman primates, including apes, monkeys, tarsiers, lemurs, and lorises. Primatology research gives us insights into how evolution has shaped our species, since nonhuman primates are our closest living biological relatives. Through such studies, we have learned that all primates share a suite of traits. Primates, for instance, have nails instead of claws, possess hands that can grasp and manipulate objects (Figure 1.12), invest great amounts of time and energy in raising a small number of offspring, and employ complex social behaviours. Behavioural studies, such as those by Jane Goodall of wild chimpanzees and others, reveal that great apes are like humans in that they have families and form strong maternal-infant relationships. Gorillas mourn the deaths of their group members, and they exhibit behaviours similar to humans such as playing and tickling. Importantly, the work of Goodall, Karen B. Strier (see Appendix B), and others focus on primate conservation: They have brought attention to the fact that 60% of primates are currently threatened with extinction (Estrada et al. 2017).<\/p>\n<figure style=\"width: 355px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image15.png\" alt=\"The head and hand of a gorilla rest on an angled tree trunk.\" width=\"355\" height=\"224\" \/><figcaption class=\"wp-caption-text\">Figure 1.12: A mountain gorillas feeds on insects. Their fingers and fingernails are very similar to that of humans. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Mountain_gorilla_finger_detail.KMRA.jpg\" target=\"_blank\">Mountain gorilla finger detail.KMRA<\/a> by Kurt Ackermann (username KMRA) is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.5\/legalcode\" target=\"_blank\">CC BY 2.5 License<\/a>.<\/figcaption><\/figure>\n<h3 class=\"import-Normal\"><strong>Paleoanthropology<\/strong><\/h3>\n<p class=\"import-Normal\">Paleoanthropologists study human ancestors from the distant past to learn how, why, and where they evolved. Because these ancestors lived before there were written records, paleoanthropologists have to rely on various types of physical evidence to come to their conclusions. This evidence includes fossilized remains (particularly fossilized bones; Figure 1.13), DNA, artifacts such as stone tools, and the contexts in which these items are found. In recent years, paleoanthropologists have made some monumental discoveries about hominin evolution.<\/p>\n<\/div>\n<div class=\"__UNKNOWN__\">\n<figure style=\"width: 358px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image10.png\" alt=\"A person looks eye-to-eye with a fossil cast.\" width=\"358\" height=\"238\" \/><figcaption class=\"wp-caption-text\">Figure 1.13: Donald Johanson and an Australopithecus fossil skull. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Donald_Johanson,_2009.jpg\" target=\"_blank\">Donald Johanson 2009<\/a> by Julesasu has been designated to the <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/cc0\/\" target=\"_blank\">public domain (CC0)<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">These findings helped us learn that human evolution did not occur in a simple, straight line but, rather, branched out in many directions. Most branches were evolutionary \u201cdead ends.\u201d Humans are now the only living hominins left on planet Earth. Paleoanthropologists frequently work together with other scientists such as archaeologists, geologists, and paleontologists to interpret and understand the evidence they find. Paleoanthropology is a dynamic subfield of biological anthropology that contributes to our understanding of human origins and evolution.<\/p>\n<h3 class=\"import-Normal\"><strong>Molecular Anthropology<\/strong><\/h3>\n<p class=\"import-Normal\">Molecular anthropologists use molecular techniques (primarily genetics) to compare ancient and modern populations as well as to study living populations of humans or nonhuman primates. By examining DNA sequences, molecular anthropologists can estimate how closely related two populations are, as well as identify population events, like a population decline, that explain the observed genetic patterns. This information helps scientists trace patterns of migration and identify how people have adapted to different environments over time.<\/p>\n<p class=\"import-Normal\">Several molecular anthropologists have recently attracted international recognition for their groundbreaking work. For instance, in 2022, Svante P\u00e4\u00e4bo won the Nobel Prize in physiology (medicine) for his work extracting the DNA from 40,000-year-old Neanderthal bones and producing the first complete genome of <em>Homo neanderthalensis<\/em>. This was a challenging task because ancient DNA does not preserve well and older extraction techniques tended to become contaminated by the researcher\u2019s and other environmental DNA. P\u00e4\u00e4bo and his team designed specialized clean rooms for handling ancient DNA and made advances in DNA sequencing. Their research helped scientists identify genetic differences between modern humans and Neanderthals and analyse how those differences influence how diseases, such as COVID-19, affect our bodies. Molecular anthropology is a quickly changing field as new techniques and discoveries shape our understanding of ourselves, our ancestors, and our nonhuman primate relatives.<\/p>\n<h3 class=\"import-Normal\"><strong>Bioarchaeology<\/strong><\/h3>\n<p class=\"import-Normal\">Bioarchaeologists study human skeletal remains along with the surrounding soils and other materials. They use the research methods of skeletal biology, mortuary studies, osteology, and archaeology to answer questions about the lifeways of past populations. Through studying the bones and burials of past peoples, bioarchaeologists search for answers to how people lived and died, including their health, nutrition, diseases, and\/or injuries. Most bioarchaeologists study not just individuals but entire populations to reveal biological and cultural patterns.<\/p>\n<p class=\"import-Normal\">People have always been intrigued by the remains of the dead, however historically, human bodies were often studied isolated from the ground and location where they were found. Bioarchaeologists emphasize the context in and around where the remains are found, using a biocultural approach that studies humans through an understanding of the interconnectedness of biology, culture, and environment.<\/p>\n<h3 class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Forensic Anthropology<\/strong><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Forensic anthropologists use many of the same techniques as bioarchaeologists to develop a biological profile for unidentified individuals, including estimating sex, age at death, height, ancestry, or other unique identifying features such as skeletal trauma or diseases. They may also go to a crime or accident scene to assist in the search and recovery of human remains, aiding law enforcement teams (Figure 1.14). The popular television show <em>Bones<\/em> told the fictional story of a forensic anthropologist, Dr. Temperance Brennan, who brilliantly interpreted clues from victims' bones to help solve crimes. While the show includes forensic anthropology techniques and responsibilities, it also includes many inaccuracies. For example, forensic anthropologists do not collect trace evidence like hair or fibres, run DNA tests, carry weapons, or solve criminal cases.<\/p>\n<figure style=\"width: 342px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image6.png\" alt=\"Woman placing flowers near a stone memorial.\" width=\"342\" height=\"228\" \/><figcaption class=\"wp-caption-text\">Figure 1.14: A remembrance of the victims of El Mozote Massacre in El Salvador. Forensic anthropologists played an important role in identifying the victims of this massacre during the Salvadoran Civil War. Credit:\u00a0<a href=\"https:\/\/www.flickr.com\/photos\/fotospresidencia_sv\/25069414908\" target=\"_blank\">Untitled<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/fotospresidencia_sv\/\" target=\"_blank\">Presidencia El Salvador <\/a>has been designated to the <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/cc0\/\" target=\"_blank\">public domain (CC0)<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Forensic anthropology is considered an applied area of biological anthropology, because it involves a practical application of anthropological theories, methods, and findings to solve real-world problems. While some forensic anthropologists are academics that work for colleges and universities, others are employed by public safety and law agencies.<\/p>\n<h3 class=\"import-Normal\"><strong>Human Biology<\/strong><\/h3>\n<p class=\"import-Normal\">Many biological anthropologists do work that falls under the label of \u201chuman biology.\u201d This type of research explores how the human body is affected by different physical environments, cultural influences, and nutrition. These include studies of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1093\">human variation<\/a><\/strong> or the physiological differences among humans around the world. Some of these anthropologists study <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1094\">human adaptations<\/a> <\/strong>to extreme environments, which includes physiological responses and genetic advantages to help them survive. Others are interested in how nutrition and disease affect human growth and development. Biological anthropologists engage in a wide range of research that spans the breadth of human biological diversity.<\/p>\n<p class=\"import-Normal\">The six subfields of biological anthropology\u2014primatology, paleoanthropology, molecular anthropology, bioarchaeology, forensic anthropology, and human biology\u2014all help us to understand what it means to be biologically human. From molecular analyses of our cells to studies of our changing skeleton, to research on our nonhuman primate cousins, biological anthropology assists in answering the central question of anthropology: What does it mean to be human? Despite their different foci, all biological anthropologists share a commitment to using a scientific approach to study how we became the complex, adaptable species we are today.<\/p>\n<h2 class=\"import-Normal\">Key Terms<\/h2>\n<p class=\"import-Normal\"><strong>Belief<\/strong>: A firmly held opinion or conviction typically based on spiritual apprehension rather than empirical proof.<\/p>\n<p class=\"import-Normal\"><strong>Cultural re<\/strong><strong>lativism<\/strong>: The anthropological practice of suspending judgment and seeking to understand another culture on its own terms sympathetically enough so that the culture appears to be a coherent and meaningful design for living.<\/p>\n<p class=\"import-Normal\"><strong>Holism<\/strong>: The idea that the parts of a system interconnect and interact to make up the whole.<\/p>\n<p class=\"import-Normal\"><strong>Hominins<\/strong>: Species that are regarded as human, directly ancestral to humans, or very closely related to humans.<\/p>\n<p class=\"import-Normal\"><strong>Human adaptation<\/strong>: The ways in which human bodies, people, or cultures change, often in ways better suited to the environment or social context.<\/p>\n<p class=\"import-Normal\"><strong>Human variation<\/strong>: The range of forms of any human characteristic, such as body shape or skin colour.<\/p>\n<p class=\"import-Normal\"><strong>Hypothesis<\/strong>: Explanation of observed facts; details how and why observed phenomena are the way they are. Scientific hypotheses rely on empirical evidence, are testable, and are able to be refuted.<\/p>\n<p class=\"import-Normal\"><strong>Indigenous<\/strong>: Refers to people who are the original settlers of a given region and have deep ties to that place. Also known as First Peoples, Aboriginal Peoples, or Native Peoples, these populations are in contrast to other groups who have settled, occupied, or colonized the area more recently.<\/p>\n<p class=\"import-Normal\"><strong>Law<\/strong>: A prediction about what will happen given certain conditions; typically mathematical.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><strong>Sapir-Whorf hypothesis<\/strong>: The principle that the language you speak allows you to think about some things and not other things. This is also known as the linguistic relativity hypothesis.<\/p>\n<p class=\"import-Normal\"><strong>Subdisciplines<\/strong>: The four major areas that make up the discipline of anthropology: biological anthropology, cultural anthropology, archaeology, and linguistic anthropology. Applied anthropology is sometimes considered to be a fifth subdiscipline.<\/p>\n<p class=\"import-Normal\"><strong>Subfield<\/strong>: In this textbook, <em>subfield<\/em> refers to the different specializations within biological anthropology, including primatology, paleoanthropology, molecular anthropology, bioarchaeology, forensic anthropology, and human biology.<\/p>\n<h2 class=\"import-Normal\">For Further Exploration<\/h2>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><a href=\"https:\/\/www.americananthro.org\/\" target=\"_blank\">American Anthropological Association website<\/a>.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><a href=\"https:\/\/bioanth.org\/\" target=\"_blank\">American Association of Biological Anthropologists website<\/a>.<\/p>\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;text-indent: 0pt\">8, 2023<\/p>\n<h2 class=\"import-Normal\">References<\/h2>\n<p class=\"import-Normal\" style=\"text-indent: 0pt\">Binford, Leigh. 2016. <em>The El Mozote Massacre: Human Rights and Global Implications.<\/em> Revised and expanded edition. Tucson: University of Arizona Press.<\/p>\n<p class=\"import-Normal\" style=\"text-indent: 0pt\">Estrada, Alejandro, Paul A. Garber, Anthony B. Rylands, Christian Roos, Eduardo Fernandez-Duque, Anthony Di Fiore, K. Anne-Isola Nekaris, et al. 2017. \u201cImpending Extinction Crisis of the World\u2019s Primates: Why Primates Matter.\u201d <em>Science Advances<\/em> 3(229): 1\u201316.<\/p>\n<p class=\"import-Normal\" style=\"text-indent: 0pt\">Farmer, Paul. 2006. <em>AIDS and Accusation: Haiti and the Geography of Blame.<\/em> Berkeley: University of California Press.<\/p>\n<p class=\"import-Normal\" style=\"text-indent: 0pt\">Farmer, Paul, Matthew Basilico, Vanessa Kerry, Madeleine Ballard, Anne Becker, Gene Bukhman, Ophelia Dahl, et al. 2013. \u201cGlobal Health Priorities for the Early Twenty-first Century.\u201d In <em>Reimagining Global Health: An Introduction, <\/em>edited by Paul Farmer, Jim Yong Kim, Arthur Kleinman, and Matthew Basilico, 302\u2013339. Berkeley: University of California Press.<\/p>\n<p class=\"import-Normal\" style=\"text-indent: 0pt\">Kenyon, Kathleen. 1979. <em>Archaeology in the Holy Land.<\/em> New York: W.W. Norton.<\/p>\n<p class=\"import-Normal\">Malotki, Ekkehart. 1983. <em>Hopi Time: A Linguistic Analysis of the Temporal Concepts in the Hopi Languag<\/em><em>e.<\/em> Berlin: De Gruyter.<\/p>\n<p class=\"import-Normal\" style=\"text-indent: 0pt\">Mead, Margaret. 1928. <em>Coming of Age in Samoa<\/em>. Oxford: Morrow.<\/p>\n<p class=\"import-Normal\">Ochs, Elinor and Bambi Schieffelin. 2017. \u201cLanguage Socialization: An Historical Overview.\u201d In <em>Encyclopedia of Language and Education, Volume 8, <\/em>edited by Patricia Duff, 3-16. New York: Springer.<\/p>\n<p class=\"import-Normal\">Rathje, William and Cullen Murphy. 1992. \"Five Major Myths about Garbage, and Why They're Wrong.\" <em>Smithsonian<\/em> 23, no. 4: 113-122.<\/p>\n<p class=\"import-Normal\" style=\"text-indent: 0pt\">TANN. 2018. <a href=\"https:\/\/archaeonewsnet.com\/2018\/08\/mexican-anthropologists-put-face-on.html\" target=\"_blank\">\u201cMexican Anthropologists Put Face on Nearly 14,000-Year-Old Woman.\u201d<\/a> <em>Archaeology News Network<\/em>, August 19, 2018<em>. <\/em>Accessed on November 16, 2022.<\/p>\n<p class=\"import-Normal\" style=\"text-indent: 0pt\">Whorf, Benjamin. 1956. <em>Language, Thought, and Reality.<\/em> Cambridge: MIT Press.<\/p>\n<h2 class=\"import-Normal\">Acknowledgment<\/h2>\n<p class=\"import-Normal\">We are grateful to the anonymous reviewers for their many insightful comments and suggestions.<\/p>\n<\/div>\n<div class=\"mceTemp\"><\/div>\n<\/div>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1695_1841\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1695_1841\"><div tabindex=\"-1\"><div class=\"textbox\">Learn more about <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/about-the-authors\/\">authors and editors<\/a>,<a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/student-contributors\/\"> Hess' student contributions<\/a>, and <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/versioning-history\/\">versioning history<\/a>.<\/div>\n<div class=\"textbox textbox--learning-objectives\">\n<header class=\"textbox__header\">\n<h2 class=\"textbox__title\">Learning Objectives<\/h2>\n<\/header>\n<div class=\"textbox__content\">\n<ul>\n<li class=\"import-Normal\">Explain key components of the scientific method.<\/li>\n<li class=\"import-Normal\">Differentiate between hypotheses, theories, and laws.<\/li>\n<li class=\"import-Normal\">Differentiate science from other ways of knowing.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<div class=\"__UNKNOWN__\">\n<h2 class=\"import-Normal\">Anthropologists as Scientists<\/h2>\n<p class=\"import-Normal\">Biological anthropologists use the scientific method as a way of learning about the world around them. Many people think of science as taking place in a sterile laboratory, but in biological anthropology it is just as likely to occur somewhere else, such as at a research station in Ethiopia, a field site in Tanzania, or a town in El Salvador. To understand how information in this field is established, it is important to recognize what science is and is not, as well as to understand how the scientific method actually works.<\/p>\n<h3 class=\"import-Normal\"><strong>Recognizing <\/strong><strong>Science<\/strong><\/h3>\n<p class=\"import-Normal\">Science combines our natural curiosity with our ability to experiment so we can understand the world around us and address needs in our communities. Thanks to science, meteorologists can predict the weather, it takes a relatively small number of farmers to grow enough food to feed our large population, our medicine continues to improve, and over half of the world\u2019s population owns a cell phone.<\/p>\n<p class=\"import-Normal\">Anyone can participate in science\u2014not just academics. In fact, children are often some of the best scientists (Figure 1.15). An early, well-known psychologist, Jean Piaget (1896\u20131980), argued that a child is a \u201clittle scientist,\u201d internally motivated to experiment and explore their world. This can be seen when an infant repeatedly drops a toy to see if the parent will pick it up, or when a four-year-old sincerely asks \u201cwhy\u201d again and again. Maria Montessori (1870\u20131952), an Italian doctor and educator, was interested in how children learn. Through her research, she also recognized that children have natural scientific tendencies. Children have a desire to explore their environment, ask questions, use their imaginations, and learn by doing. In 1907, Montessori opened a school to foster children\u2019s natural desire to learn this way. This developed a child-centreed teaching method that has spread around the world and is being used in over 22,000 schools today. In anthropology and other scientific fields, the process of learning is more formalized, but scientists still benefit from the curiosity that motivates children and still experience the thrill of discovery.<\/p>\n<figure style=\"width: 365px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image19.jpg\" alt=\"Toddler presses their hands and face against a large window.\" width=\"365\" height=\"243\" \/><figcaption class=\"wp-caption-text\">Figure 1.15: Children are true scientists as they explore and test the world around them through sight and touch. Credit: Child Scientist at Window original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Beth Shook is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Science represents both a body of knowledge and the process for learning that knowledge (the scientific method). Scientific claims can, at times, be difficult to distinguish from other information. Science also incorporates a broad range of methods to collect data, adding to the difficulty of knowing what science really is. This section will address four key characteristics that help us define and recognize science: (1) science studies the physical and natural world and how it works, (2) scientific explanations must be testable and refutable, (3) science relies on <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1095\">empirical<\/a><\/strong> (observable) evidence, and (4) science involves the scientific community.<\/p>\n<h4 class=\"import-Normal\"><em>Science Studies the Physical and Natural World and How It Works<\/em><\/h4>\n<p class=\"import-Normal\">Our physical and natural universe ranges from very small (e.g., electrons) to very large (e.g., Earth itself and the galaxies beyond it). Scientists often design their research to address how and why natural forces influence our physical and natural world. In biological anthropology, we focus our questions on humans as well as other primate species, both living and extinct. We ask questions like: What influences a primate\u2019s diet? Why do humans walk on two legs? And did Neanderthals and modern humans interbreed?<\/p>\n<p class=\"import-Normal\">There are very few questions that are considered off-limits in science. That being said, the scope of scientific investigation is generally focused on <em>natural<\/em> phenomena and <em>natural<\/em> processes and excludes the supernatural. People often regard the supernatural, whether it be a ghost, luck, or god, as working outside the laws of the universe, which makes it difficult to study with a scientific approach. Science neither supports nor contradicts the existence of supernatural powers\u2014it simply does not include the supernatural in its explanations.<\/p>\n<h4 class=\"import-Normal\"><em>Scientific Explanations Must Be Testable and Refutable<\/em><\/h4>\n<p class=\"import-Normal\">The goal of scientists is to identify a research question and then identify the best answer(s) to that question. For example, an excavation of a cemetery may reveal that many people buried there had unhealed fractures when they died, leading the anthropologist to ask: \u201cWhy did this population experience more broken bones than their neighbours?\u201d There might be multiple explanations to address this question, such as a lack of calcium in their diets, participation in dangerous work, or violent conflict with neighbours; these explanations are considered hypotheses. In the past, you might have learned that a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1096\">hypothesis<\/a><\/strong> is an \u201ceducated guess,\u201d but in science, hypotheses are much more than that. A scientific hypothesis reflects a scientist\u2019s knowledge-based experiences and background research. A hypothesis is better defined as an explanation of observed facts; hypotheses explain how and why observed phenomena are the way they are.<\/p>\n<p class=\"import-Normal\">Scientific hypotheses should generate expectations that are <em>testable<\/em><em>. <\/em>For example, if the best explanation regarding our cemetery population was that they were experiencing violent conflict with their neighbours, we should expect to find clues, like weapons or protective walls around their homes, in the anthropological record to support this. Alternatively, if this population did not experience violent conflict with their neighbours, we may eventually be able to gather enough evidence to rule out (refute) this explanation. An important part of science is rigorous testing. Science <em>does not prove<\/em> any hypothesis. However, a strong hypothesis is one that has strong supporting evidence and has not yet been disproven.<\/p>\n<h4 class=\"import-Normal\"><em>Science Relies on Empirical Evidence<\/em><\/h4>\n<p class=\"import-Normal\">The word <em>emp<\/em><em>irical<\/em> refers to experience that is verified by observation (rather than evidence that derives primarily from logic or theory). In anthropology, much evidence about our world is collected by observation through fieldwork or in a laboratory. The most reliable studies are based on accurately and precisely recorded observations. Scientists value studies that explain exactly what methods were used so that their data collection and analysis processes are reproducible. This allows for other scientists to expand the study or provide new insights into the observations.<\/p>\n<h4 class=\"import-Normal\"><em>Science Involves the Scientific Community<\/em><\/h4>\n<p class=\"import-Normal\">Contrary to many Hollywood science fiction films, good science is not carried out in isolation in a secret basement laboratory; rather, it is done as part of a community. Scientists pay attention to what others have done before them, present new ideas to each other, and publish in scientific journals. Most scientific research is collaborative, bringing together researchers with different types of specialized knowledge to work on a shared project. Today, thanks to technology, scientific projects can bring together researchers from different backgrounds, experiences, locations, and perspectives. Most big anthropological questions such as \u201cWhere did modern humans develop?,\u201d \u201cWhat genetic changes make us uniquely human?,\u201d and \u201cHow did cooperative behaviour evolve?\u201d cannot be addressed with one simple study but are tested with different lines of evidence and by different scientists over time.<\/p>\n<p class=\"import-Normal\">Working within a scientific community supports one of the most valuable aspects of science: that <em>science is self-correcting<\/em>. Science that is openly communicated with others allows for a system with checks and balances: competing explanations can be proposed and questionable studies can be reevaluated. Ultimately, the goal is that through science the best explanations will stand the test of time.<\/p>\n<h3 class=\"import-Normal\"><strong>How Science Works: The Scientific Method<\/strong><\/h3>\n<p class=\"import-Normal\">Most students have learned the scientific method as a simple linear, or perhaps circular, process (see, e.g., Figure 1.16). Typically, the process is said to begin with making observations about the natural world. This leads to the development of a scientific hypothesis. From the hypothesis a set of predictions can be made, which are then tested by experimentation or by making additional observations. Scientific predictions are often phrased as \u201cif... then\u2026\u201d statements, such as \u201cIf hypothesis A is true, then this experiment will show outcome B.\u201d The results of a scientific study should then either support or reject the hypothesis.<\/p>\n<figure style=\"width: 558px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image3.png\" alt=\"Five text boxes depict the steps in the scientific method.\" width=\"558\" height=\"102\" \/><figcaption class=\"wp-caption-text\">Figure 1.16: Simple depiction of the scientific method. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-2\/\" target=\"_blank\">Simple depiction of the scientific method (Figure 1.23)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">This simple version of the scientific method is valuable because it highlights the key aspects that should be present in any scientific research experiment or scientific paper. However, this simplistic view does not accurately represent the dynamic and creative side of science, nor does it identify the complex steps that are incorporated into a scientist\u2019s routine.<\/p>\n<figure style=\"width: 523px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image4.png\" alt=\"Circles and arrows depict the more complex process of how science works.\" width=\"523\" height=\"676\" \/><figcaption class=\"wp-caption-text\">Figure 1.17: Complex flow of the scientific method. <a href=\"https:\/\/undsci.berkeley.edu\/the-understanding-science-flowchart-text-description\/\" target=\"_blank\" rel=\"noopener\">A full text description is available from Understanding Science<\/a>. Credit: <a href=\"https:\/\/undsci.berkeley.edu\/teaching\/teachingtools.php\" target=\"_blank\" rel=\"noopener\">Complex Science Flowchart<\/a> (2022) by <a href=\"https:\/\/undsci.berkeley.edu\/\" target=\"_blank\">Understanding Science, University of California Museum of Paleontology<\/a> is used by permission and available here under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Figure 1.17 provides an alternative representation of the scientific method that emphasizes the many paths to scientific discovery. While still incorporating the key components of making observations, testing ideas, and interpreting results, this chart shows that scientific ideas have many possible starting points and influences, and scientists often repeat steps and circle back around. Gathering evidence does not always rest on experiments in the laboratory. Evaluating data is not always clear-cut, and results are sometimes surprising or inconclusive. Many important discoveries were in fact made by mistake. For example, engineer Percy Spencer accidentally melted a chocolate bar in his pocket with a magnetron, which became the first microwave, and Spencer Silver invented the adhesive for 3M Post-it \u00ae notes while trying to develop a strong glue. The real scientific process is more similar to the philosophy of the animated television character Ms. Frizzle from <em>The Magic School Bus<\/em>, \u201cTake chances, make mistakes, get messy.\u201d<\/p>\n<p class=\"import-Normal\">Two key components lacking in the simple version of the scientific method are exploration and discovery. There are many reasons that a scientist might choose a particular research question: they may be motivated by personal experience, struck by something they read, or inspired by a student\u2019s question in class. Often scientific research reveals more questions than answers, so experienced researchers rarely lack problems to solve. But identifying a research question is just part of the process; most scientists spend more time exploring the literature, sharing ideas, asking questions, and planning their research project than conducting the test itself.<\/p>\n<p class=\"import-Normal\">Science itself is a social enterprise that is influenced by cultural issues and values, as well as funding priorities. For example, corporations are the biggest funders of scientific research, followed by government agencies such as the National Science Foundation (which also fund many research projects done at colleges and universities). Those organizations have great influence on what is considered valuable research at any given time. For example, the World Health Organization (WHO) has classified many diseases as \u201cneglected tropical diseases,\u201d including dengue, leprosy, rabies, and hookworm. Together these diseases affect an estimated one billion people, mostly in impoverished areas. While these debilitating tropical diseases can be as deadly as diseases that receive more attention, like AIDS and tuberculosis, they receive comparatively little funding due to political priorities (Farmer et al. 2013).<\/p>\n<p class=\"import-Normal\">Also important to the scientific process are interactions within the scientific community. Scientific collaboration can take place through informal discussion over a cup of coffee as well as more formal interactions, such as presenting at conferences and engaging in <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1097\">scholarly peer review<\/a><\/strong>. Scholarly peer review describes the process whereby an author\u2019s work must pass the scrutiny of other experts in the field before being accepted for publication in a journal or book. This helps keep scientists accountable for ethically responsible research projects and papers. Additionally, presenting data at conferences and in articles and books allows researchers to receive critical feedback from academic peers and others to test these ideas and further the field of science toward identifying the best explanations. It is important that the scientific field include researchers with diverse identities, backgrounds, and experiences so that researchers ask new questions, innovate, and problem solve more effectively.<\/p>\n<h3 class=\"import-Normal\"><strong>Hypotheses, Theories, and Laws<\/strong><\/h3>\n<p class=\"import-Normal\">Scientific investigation occurs at many levels, from investigating individual cases (e.g., \u201cWhat is causing this child\u2019s mysterious illness?\u201d) to understanding processes that affect most of us (\u201cWhat is the ideal amount of sleep for an adult?\u201d). All of these questions are important and will generate different types of testable scientific explanations. So far, we have used the term <em>hypothesis<\/em> to describe these scientific ideas about why observed phenomena are the way they are. Hypotheses are typically explanations that address a narrow set of phenomena, such as (in anthropology) a particular human population or primate species.<\/p>\n<p class=\"import-Normal\">In science, a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1098\">theory<\/a> <\/strong>is an explanation of observations that addresses a wide range of phenomena. Like hypotheses, theories also explain how or why something occurs, rely on empirical evidence, and are testable and able to be refuted. Because the term <em>theory<\/em> is often used casually outside of science, you may hear people try to dismiss a scientific claim as \u201cjust a theory.\u201d In science there are often multiple competing theories, but over time some are eliminated, leaving standing the theory or theories that best explain the most evidence. Scientific theories that have stood the test of time are thus supported by many lines of evidence and are usually reliable. Some well-tested theories accepted by most scientists include the theory of general relativity, which explains the law of gravitation and its relation to other forces, and evolutionary theory, which describes how heritable traits can change in a population over time.<\/p>\n<p class=\"import-Normal\">While scientific hypotheses and theories share many characteristics, laws are quite different. A <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1099\">law<\/a> <\/strong>is a <em>prediction<\/em> about what will happen given certain conditions, <em>not<\/em> an explanation for how or why it happens. A law is not a \u201cmature\u201d version of a theory. For example, Newton\u2019s universal law of gravity allows us to predict the gravitational force (F) between any two objects using the equation F=G(m<sub>1<\/sub>m<sub>2<\/sub>)\/r<sup>2<\/sup>, but it does not explain <em>why<\/em> gravity works. Laws are often mathematical, and some well-known laws include Newton\u2019s three laws of motion and Mendel\u2019s laws of genetic inheritance. Laws are important, and their discovery often promotes the development of theories.<\/p>\n<figure style=\"width: 290px\" class=\"wp-caption alignright\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image8.png\" alt=\"People with surprised expressions stand as a naked man runs by.\" width=\"290\" height=\"174\" \/><figcaption class=\"wp-caption-text\">Figure 1.18: Archimedes is portrayed here having just discovered his Principle of Buoyancy. The vignette is by Count Giammaria Mazzuchelli (1707\u20131765). Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Eureka!_Archimede.jpg\" target=\"_blank\">Eureka! Archimede<\/a> by <a href=\"https:\/\/www.ssplprints.com\/\" target=\"_blank\">Science and Society Piture Library Prints<\/a> is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\" target=\"_blank\">public domain<\/a>. [This image is a faithful photographic reproduction of \u201cArchimedes' Principle\u201d vignette from \"Historical and Critical Information about the Life, Inventions and Writings of Archimedes of Syracuse\" by Count Giammaria Mazzuchelli (1707\u20131765), published in Brescia, Italy in 1737.]<\/figcaption><\/figure>\n<p class=\"import-Normal\">To demonstrate how important laws can be\u2014and to show how unusual things can inspire scientific discoveries\u2014we can use the story of the ancient Greek mathematician and inventor Archimedes (Figure 1.18). Archimedes\u2019s buoyancy principle is a law that is useful for many things, including density calculations and designing ships. Purportedly, he made this discovery when he noticed the water level rise in the bathtub when he climbed in it. Realizing its importance, he is said to have shouted \u201cEureka\u201d and proceeded to run naked through the city of Syracuse. While this fun story may or may not be true, it does remain that scientific laws, alongside scientific hypotheses and theories, have a very important role in the scientific process and in generating scientific explanations about our natural world.<\/p>\n<h2 class=\"import-Normal\">Ways of Knowing: Science, Faith, and Anthropology<\/h2>\n<p class=\"import-Normal\">In anthropology, we recognize that there are many ways of knowing things. For instance, you might know that fingernails are softer than metal because as a child you accidentally stapled through your fingernail while doing an art project (a coauthor of this textbook once experienced this). This would be an example of knowledge you gained through experience. You might also know that inserting a knife into an electrical outlet is dangerous and could greatly harm you. Hopefully you learned this not from personal experience but through instruction from parents, teachers, and others in your social group. The degree to which humans rely on and benefit from the experiential knowledge of others is an important characteristic of what makes us human.<\/p>\n<p class=\"import-Normal\">A unified way of knowing that is shared by a group of people and used to explain and predict phenomena is called a<strong> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1100\">knowledge system<\/a><\/strong>. Human knowledge systems are diverse and reflect the wide range of cultures and societies throughout the world and through time.<\/p>\n<p class=\"import-Normal\">Science and religion are both knowledge systems. Yet they differ in important ways. The type of knowledge gained from science is often called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1101\">scientific understanding<\/a><\/strong>. As we have explored in the previous section, scientific understanding can change and relies on evidence and rigorous, repeated testing. Religious or spiritual ways of knowing are called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1102\">belief<\/a><\/strong>, which is different from scientific understanding because they do not require repeated testing or validation (although they can rely on observations and experiences). Instead, belief relies on trust and<strong> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1103\">faith<\/a><\/strong>.<\/p>\n<p class=\"import-Normal\">Different individuals, cultures, and societies may place more value on one type of knowing than another, although most use a combination that includes science, empiricism, and religion. In fact, Bronis\u0142aw Malinowski (1884\u20131942), an important anthropologist of the early twentieth century, concluded that all societies use both religion <em>and<\/em> science in some way or another, because they are both common ways that humans experience the world.<\/p>\n<p class=\"import-Normal\">In contemporary societies such as the United States, science and (some) religions conflict on the topic of human origins. Nearly every culture and society has a unique origin story that explains where they came from and how they came to be who they are today. These stories are often integrated into the culture\u2019s religious belief system. Many anthropologists are interested in faith-based origin stories and other beliefs because they show us how a particular group of people explain the world and their place in it. Anthropologists also value scientific understanding as the basis for how humans vary biologically and change over time. In other words, anthropologists value the multiple knowledge systems of different groups and use them to understand the human condition in a broad and inclusive way.<\/p>\n<p class=\"import-Normal\">It is also important to note that scientists often depend on the local knowledge of the people with whom they work to understand elements of the natural or physical world that science has not yet investigated. Many groups, including <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1473\">Indigenous<\/a><\/strong> peoples, know about the world through prolonged relationships with the environment. Indigenous knowledge systems\u2014specific to an Indigenous community or group\u2014are informed by their own empirical observation of a specific environment and passed down over generations.<\/p>\n<p class=\"import-Normal\">While religion and Indigenous knowledge systems may play a complementary role in helping anthropologists understand the human condition, they are distinct from science. The anthropological subdiscipline of biological anthropology is based on scientific ways of knowing about humans and human origins. In this volume, we will exclusively explore what science tells us about how humans came to be and why we are the way we are today. Therefore, you do not need to <em>believe<\/em> in evolution to master this material, because belief is not a scientific way of knowing. For this textbook, you only need to <em>understand <\/em>the scientific perspectives of evolution.<\/p>\n<p class=\"import-Normal\">Throughout our lives, each of us work to reconcile our worldview with the different ways we have of knowing things. This is part of our lifelong intellectual journey. It is also, in our opinion, one of the most exciting parts of learning. We are pleased you have joined us on this journey of knowledge about humanity and yourself!<\/p>\n<p>&nbsp;<\/p>\n<div class=\"textbox shaded\">\n<h2>Summary<\/h2>\n<p>Biological anthropology relies on the scientific method to investigate humans and other primates across time and place. While research in this field begins with careful observation, hypotheses are more closely examined with empirical evidence from excavation, fieldwork, or laboratory study. Focusing on this scientific foundation, the discipline allows anthropologists to move beyond belief and speculation to produce knowledge that is testable and continually open to challenge.<\/p>\n<p>Findings are continually debated, reviewed, and revised, ensuring that explanations improve and remain grounded in current and relevant evidence. If you have not caught on already, this textbook follows the same process, reflecting the evolving body of knowledge that is biological anthropology.<\/p>\n<h2 class=\"import-Normal\">Review Questions<\/h2>\n<ul>\n<li class=\"import-Normal\">What is science?<\/li>\n<li class=\"import-Normal\">What is the scientific method?<\/li>\n<li class=\"import-Normal\">How does science compare to other ways of knowing?<\/li>\n<\/ul>\n<\/div>\n<h2 class=\"import-Normal\">Key Terms<\/h2>\n<p class=\"import-Normal\"><strong>Empirical<\/strong>: Evidence that is verifiable by observation or experience instead of relying primarily on logic or theory.<\/p>\n<p class=\"import-Normal\"><strong>Faith<\/strong>: Complete trust or confidence in the doctrines of a religion, typically based on spiritual apprehension rather than empirical proof.<\/p>\n<p class=\"import-Normal\"><strong>Knowledge system<\/strong>: A unified way of knowing that is shared by a group of people and used to explain and predict phenomena.<\/p>\n<p class=\"import-Normal\"><strong>Participant observation<\/strong>: A research method common in cultural anthropology that involves living with, observing, and participating in the same activities as the people one studies.<\/p>\n<p class=\"import-Normal\"><strong>Scholarly peer review<\/strong>: The process whereby an author\u2019s work must pass the scrutiny of other experts in the field before being published in a journal or book.<\/p>\n<p class=\"import-Normal\"><strong>Scientific u<\/strong><strong>nderstanding<\/strong>: Knowledge accumulated by systematic scientific study, supported by rigorous testing and organized by general principles.<\/p>\n<p class=\"import-Normal\"><strong>Theory<\/strong>: An explanation of observations that typically addresses a wide range of phenomena.<\/p>\n<h2 class=\"import-Normal\">For Further Exploration<\/h2>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><a href=\"https:\/\/www.understandingscience.org\" target=\"_blank\">Understanding Science website<\/a> (a project of the University of California Museum of Paleontology.<\/p>\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #333333\">Anticole, Matt. n.d. <a href=\"https:\/\/ed.ted.com\/lessons\/what-s-the-difference-between-a-scientific-law-and-theory-matt-anticole#watch\" target=\"_blank\">\u201cWhat\u2019s the Difference between a Scientific Law and Theory?\"<\/a> TedEd Lesson. \u00a0Accessed January 28, 2023.<\/span> 28, 2023.<\/p>\n<p class=\"import-Normal\">Chan, Keith. 2021. \u201cIcebreaker Science.\u201d In <a href=\"https:\/\/explorations.americananthro.org\" target=\"_blank\"><em>Explorations<\/em><em>:<\/em><em> Lab and Activities Manual<\/em><\/a>, edited by Beth Shook, Katie Nelson, Kelsie Aguilera, and Lara Braff. Arlington, VA: American Anthropological Association.<\/p>\n<p class=\"import-Normal\">Chizmeshya, Sydney Quinn, and Katherine E. Brent. 2021. \u201cKnowing and Believing.\u201d In <a href=\"https:\/\/explorations.americananthro.org\" target=\"_blank\"><em>Explorations:<\/em> <em>Lab and Activities Manual<\/em><\/a>, edited by Beth Shook, Katie Nelson, Kelsie Aguilera, and Lara Braff. Arlington, VA: American Anthropological Association.<\/p>\n<p class=\"import-Normal\">Pfister, Anne E. 2021. \u201cScience and Belief: Just Because We Can, Doesn\u2019t Always Mean We Should.\u201d In <a href=\"https:\/\/explorations.americananthro.org\" target=\"_blank\"><em>Explorations: Lab and Activities Manual<\/em><\/a> edited by Beth Shook, Katie Nelson, Kelsie Aguilera, and Lara Braff. Arlington, VA: American Anthropological Association.<\/p>\n<h2 class=\"import-Normal\">References<\/h2>\n<p class=\"import-Normal\" style=\"text-indent: 0pt\">Binford, Leigh. 2016. <em>The El Mozote Massacre: Human Rights and Global Implications.<\/em> Revised and expanded edition. Tucson: University of Arizona Press.<\/p>\n<p class=\"import-Normal\" style=\"text-indent: 0pt\">Estrada, Alejandro, Paul A. Garber, Anthony B. Rylands, Christian Roos, Eduardo Fernandez-Duque, Anthony Di Fiore, K. Anne-Isola Nekaris, et al. 2017. \u201cImpending Extinction Crisis of the World\u2019s Primates: Why Primates Matter.\u201d <em>Science Advances<\/em> 3(229): 1\u201316.<\/p>\n<p class=\"import-Normal\" style=\"text-indent: 0pt\">Farmer, Paul. 2006. <em>AIDS and Accusation: Haiti and the Geography of Blame.<\/em> Berkeley: University of California Press.<\/p>\n<p class=\"import-Normal\" style=\"text-indent: 0pt\">Farmer, Paul, Matthew Basilico, Vanessa Kerry, Madeleine Ballard, Anne Becker, Gene Bukhman, Ophelia Dahl, et al. 2013. \u201cGlobal Health Priorities for the Early Twenty-first Century.\u201d In <em>Reimagining Global Health: An Introduction, <\/em>edited by Paul Farmer, Jim Yong Kim, Arthur Kleinman, and Matthew Basilico, 302\u2013339. Berkeley: University of California Press.<\/p>\n<p class=\"import-Normal\" style=\"text-indent: 0pt\">Kenyon, Kathleen. 1979. <em>Archaeology in the Holy Land.<\/em> New York: W.W. Norton.<\/p>\n<p class=\"import-Normal\">Malotki, Ekkehart. 1983. <em>Hopi Time: A Linguistic Analysis of the Temporal Concepts in the Hopi Languag<\/em><em>e.<\/em> Berlin: De Gruyter.<\/p>\n<p class=\"import-Normal\" style=\"text-indent: 0pt\">Mead, Margaret. 1928. <em>Coming of Age in Samoa<\/em>. Oxford: Morrow.<\/p>\n<p class=\"import-Normal\">Ochs, Elinor and Bambi Schieffelin. 2017. \u201cLanguage Socialization: An Historical Overview.\u201d In <em>Encyclopedia of Language and Education, Volume 8, <\/em>edited by Patricia Duff, 3-16. New York: Springer.<\/p>\n<p class=\"import-Normal\">Rathje, William and Cullen Murphy. 1992. \"Five Major Myths about Garbage, and Why They're Wrong.\" <em>Smithsonian<\/em> 23, no. 4: 113-122.<\/p>\n<p class=\"import-Normal\" style=\"text-indent: 0pt\">TANN. 2018. <a href=\"https:\/\/archaeonewsnet.com\/2018\/08\/mexican-anthropologists-put-face-on.html\" target=\"_blank\">\u201cMexican Anthropologists Put Face on Nearly 14,000-Year-Old Woman.\u201d<\/a> <em>Archaeology News Network<\/em>, August 19, 2018<em>. <\/em>Accessed on November 16, 2022.<\/p>\n<p class=\"import-Normal\" style=\"text-indent: 0pt\">Whorf, Benjamin. 1956. <em>Language, Thought, and Reality.<\/em> Cambridge: MIT Press.<\/p>\n<\/div>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1695_1842\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1695_1842\"><div tabindex=\"-1\"><div class=\"textbox\">Learn more about <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/about-the-authors\/\">authors and editors<\/a>,<a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/student-contributors\/\"> Hess' student contributions<\/a>, and <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/versioning-history\/\">versioning history<\/a>.<\/div>\n<div class=\"textbox textbox--learning-objectives\">\n<header class=\"textbox__header\">\n<h2 class=\"textbox__title\">Learning Objectives<\/h2>\n<\/header>\n<div class=\"textbox__content\">\n<ul>\n<li class=\"import-Normal\">Explain key components of the scientific method.<\/li>\n<li class=\"import-Normal\">Differentiate between hypotheses, theories, and laws.<\/li>\n<li class=\"import-Normal\">Differentiate science from other ways of knowing.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<div class=\"__UNKNOWN__\">\n<h2 class=\"import-Normal\">Anthropologists as Scientists<\/h2>\n<p class=\"import-Normal\">Biological anthropologists use the scientific method as a way of learning about the world around them. Many people think of science as taking place in a sterile laboratory, but in biological anthropology it is just as likely to occur somewhere else, such as at a research station in Ethiopia, a field site in Tanzania, or a town in El Salvador. To understand how information in this field is established, it is important to recognize what science is and is not, as well as to understand how the scientific method actually works.<\/p>\n<h3 class=\"import-Normal\"><strong>Recognizing <\/strong><strong>Science<\/strong><\/h3>\n<p class=\"import-Normal\">Science combines our natural curiosity with our ability to experiment so we can understand the world around us and address needs in our communities. Thanks to science, meteorologists can predict the weather, it takes a relatively small number of farmers to grow enough food to feed our large population, our medicine continues to improve, and over half of the world\u2019s population owns a cell phone.<\/p>\n<p class=\"import-Normal\">Anyone can participate in science\u2014not just academics. In fact, children are often some of the best scientists (Figure 1.15). An early, well-known psychologist, Jean Piaget (1896\u20131980), argued that a child is a \u201clittle scientist,\u201d internally motivated to experiment and explore their world. This can be seen when an infant repeatedly drops a toy to see if the parent will pick it up, or when a four-year-old sincerely asks \u201cwhy\u201d again and again. Maria Montessori (1870\u20131952), an Italian doctor and educator, was interested in how children learn. Through her research, she also recognized that children have natural scientific tendencies. Children have a desire to explore their environment, ask questions, use their imaginations, and learn by doing. In 1907, Montessori opened a school to foster children\u2019s natural desire to learn this way. This developed a child-centreed teaching method that has spread around the world and is being used in over 22,000 schools today. In anthropology and other scientific fields, the process of learning is more formalized, but scientists still benefit from the curiosity that motivates children and still experience the thrill of discovery.<\/p>\n<figure style=\"width: 365px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image19.jpg\" alt=\"Toddler presses their hands and face against a large window.\" width=\"365\" height=\"243\" \/><figcaption class=\"wp-caption-text\">Figure 1.15: Children are true scientists as they explore and test the world around them through sight and touch. Credit: Child Scientist at Window original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Beth Shook is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Science represents both a body of knowledge and the process for learning that knowledge (the scientific method). Scientific claims can, at times, be difficult to distinguish from other information. Science also incorporates a broad range of methods to collect data, adding to the difficulty of knowing what science really is. This section will address four key characteristics that help us define and recognize science: (1) science studies the physical and natural world and how it works, (2) scientific explanations must be testable and refutable, (3) science relies on <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1095\">empirical<\/a><\/strong> (observable) evidence, and (4) science involves the scientific community.<\/p>\n<h4 class=\"import-Normal\"><em>Science Studies the Physical and Natural World and How It Works<\/em><\/h4>\n<p class=\"import-Normal\">Our physical and natural universe ranges from very small (e.g., electrons) to very large (e.g., Earth itself and the galaxies beyond it). Scientists often design their research to address how and why natural forces influence our physical and natural world. In biological anthropology, we focus our questions on humans as well as other primate species, both living and extinct. We ask questions like: What influences a primate\u2019s diet? Why do humans walk on two legs? And did Neanderthals and modern humans interbreed?<\/p>\n<p class=\"import-Normal\">There are very few questions that are considered off-limits in science. That being said, the scope of scientific investigation is generally focused on <em>natural<\/em> phenomena and <em>natural<\/em> processes and excludes the supernatural. People often regard the supernatural, whether it be a ghost, luck, or god, as working outside the laws of the universe, which makes it difficult to study with a scientific approach. Science neither supports nor contradicts the existence of supernatural powers\u2014it simply does not include the supernatural in its explanations.<\/p>\n<h4 class=\"import-Normal\"><em>Scientific Explanations Must Be Testable and Refutable<\/em><\/h4>\n<p class=\"import-Normal\">The goal of scientists is to identify a research question and then identify the best answer(s) to that question. For example, an excavation of a cemetery may reveal that many people buried there had unhealed fractures when they died, leading the anthropologist to ask: \u201cWhy did this population experience more broken bones than their neighbours?\u201d There might be multiple explanations to address this question, such as a lack of calcium in their diets, participation in dangerous work, or violent conflict with neighbours; these explanations are considered hypotheses. In the past, you might have learned that a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1096\">hypothesis<\/a><\/strong> is an \u201ceducated guess,\u201d but in science, hypotheses are much more than that. A scientific hypothesis reflects a scientist\u2019s knowledge-based experiences and background research. A hypothesis is better defined as an explanation of observed facts; hypotheses explain how and why observed phenomena are the way they are.<\/p>\n<p class=\"import-Normal\">Scientific hypotheses should generate expectations that are <em>testable<\/em><em>. <\/em>For example, if the best explanation regarding our cemetery population was that they were experiencing violent conflict with their neighbours, we should expect to find clues, like weapons or protective walls around their homes, in the anthropological record to support this. Alternatively, if this population did not experience violent conflict with their neighbours, we may eventually be able to gather enough evidence to rule out (refute) this explanation. An important part of science is rigorous testing. Science <em>does not prove<\/em> any hypothesis. However, a strong hypothesis is one that has strong supporting evidence and has not yet been disproven.<\/p>\n<h4 class=\"import-Normal\"><em>Science Relies on Empirical Evidence<\/em><\/h4>\n<p class=\"import-Normal\">The word <em>emp<\/em><em>irical<\/em> refers to experience that is verified by observation (rather than evidence that derives primarily from logic or theory). In anthropology, much evidence about our world is collected by observation through fieldwork or in a laboratory. The most reliable studies are based on accurately and precisely recorded observations. Scientists value studies that explain exactly what methods were used so that their data collection and analysis processes are reproducible. This allows for other scientists to expand the study or provide new insights into the observations.<\/p>\n<h4 class=\"import-Normal\"><em>Science Involves the Scientific Community<\/em><\/h4>\n<p class=\"import-Normal\">Contrary to many Hollywood science fiction films, good science is not carried out in isolation in a secret basement laboratory; rather, it is done as part of a community. Scientists pay attention to what others have done before them, present new ideas to each other, and publish in scientific journals. Most scientific research is collaborative, bringing together researchers with different types of specialized knowledge to work on a shared project. Today, thanks to technology, scientific projects can bring together researchers from different backgrounds, experiences, locations, and perspectives. Most big anthropological questions such as \u201cWhere did modern humans develop?,\u201d \u201cWhat genetic changes make us uniquely human?,\u201d and \u201cHow did cooperative behaviour evolve?\u201d cannot be addressed with one simple study but are tested with different lines of evidence and by different scientists over time.<\/p>\n<p class=\"import-Normal\">Working within a scientific community supports one of the most valuable aspects of science: that <em>science is self-correcting<\/em>. Science that is openly communicated with others allows for a system with checks and balances: competing explanations can be proposed and questionable studies can be reevaluated. Ultimately, the goal is that through science the best explanations will stand the test of time.<\/p>\n<h3 class=\"import-Normal\"><strong>How Science Works: The Scientific Method<\/strong><\/h3>\n<p class=\"import-Normal\">Most students have learned the scientific method as a simple linear, or perhaps circular, process (see, e.g., Figure 1.16). Typically, the process is said to begin with making observations about the natural world. This leads to the development of a scientific hypothesis. From the hypothesis a set of predictions can be made, which are then tested by experimentation or by making additional observations. Scientific predictions are often phrased as \u201cif... then\u2026\u201d statements, such as \u201cIf hypothesis A is true, then this experiment will show outcome B.\u201d The results of a scientific study should then either support or reject the hypothesis.<\/p>\n<figure style=\"width: 558px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image3.png\" alt=\"Five text boxes depict the steps in the scientific method.\" width=\"558\" height=\"102\" \/><figcaption class=\"wp-caption-text\">Figure 1.16: Simple depiction of the scientific method. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-2\/\" target=\"_blank\">Simple depiction of the scientific method (Figure 1.23)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">This simple version of the scientific method is valuable because it highlights the key aspects that should be present in any scientific research experiment or scientific paper. However, this simplistic view does not accurately represent the dynamic and creative side of science, nor does it identify the complex steps that are incorporated into a scientist\u2019s routine.<\/p>\n<figure style=\"width: 523px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image4.png\" alt=\"Circles and arrows depict the more complex process of how science works.\" width=\"523\" height=\"676\" \/><figcaption class=\"wp-caption-text\">Figure 1.17: Complex flow of the scientific method. <a href=\"https:\/\/undsci.berkeley.edu\/the-understanding-science-flowchart-text-description\/\" target=\"_blank\" rel=\"noopener\">A full text description is available from Understanding Science<\/a>. Credit: <a href=\"https:\/\/undsci.berkeley.edu\/teaching\/teachingtools.php\" target=\"_blank\" rel=\"noopener\">Complex Science Flowchart<\/a> (2022) by <a href=\"https:\/\/undsci.berkeley.edu\/\" target=\"_blank\">Understanding Science, University of California Museum of Paleontology<\/a> is used by permission and available here under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Figure 1.17 provides an alternative representation of the scientific method that emphasizes the many paths to scientific discovery. While still incorporating the key components of making observations, testing ideas, and interpreting results, this chart shows that scientific ideas have many possible starting points and influences, and scientists often repeat steps and circle back around. Gathering evidence does not always rest on experiments in the laboratory. Evaluating data is not always clear-cut, and results are sometimes surprising or inconclusive. Many important discoveries were in fact made by mistake. For example, engineer Percy Spencer accidentally melted a chocolate bar in his pocket with a magnetron, which became the first microwave, and Spencer Silver invented the adhesive for 3M Post-it \u00ae notes while trying to develop a strong glue. The real scientific process is more similar to the philosophy of the animated television character Ms. Frizzle from <em>The Magic School Bus<\/em>, \u201cTake chances, make mistakes, get messy.\u201d<\/p>\n<p class=\"import-Normal\">Two key components lacking in the simple version of the scientific method are exploration and discovery. There are many reasons that a scientist might choose a particular research question: they may be motivated by personal experience, struck by something they read, or inspired by a student\u2019s question in class. Often scientific research reveals more questions than answers, so experienced researchers rarely lack problems to solve. But identifying a research question is just part of the process; most scientists spend more time exploring the literature, sharing ideas, asking questions, and planning their research project than conducting the test itself.<\/p>\n<p class=\"import-Normal\">Science itself is a social enterprise that is influenced by cultural issues and values, as well as funding priorities. For example, corporations are the biggest funders of scientific research, followed by government agencies such as the National Science Foundation (which also fund many research projects done at colleges and universities). Those organizations have great influence on what is considered valuable research at any given time. For example, the World Health Organization (WHO) has classified many diseases as \u201cneglected tropical diseases,\u201d including dengue, leprosy, rabies, and hookworm. Together these diseases affect an estimated one billion people, mostly in impoverished areas. While these debilitating tropical diseases can be as deadly as diseases that receive more attention, like AIDS and tuberculosis, they receive comparatively little funding due to political priorities (Farmer et al. 2013).<\/p>\n<p class=\"import-Normal\">Also important to the scientific process are interactions within the scientific community. Scientific collaboration can take place through informal discussion over a cup of coffee as well as more formal interactions, such as presenting at conferences and engaging in <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1097\">scholarly peer review<\/a><\/strong>. Scholarly peer review describes the process whereby an author\u2019s work must pass the scrutiny of other experts in the field before being accepted for publication in a journal or book. This helps keep scientists accountable for ethically responsible research projects and papers. Additionally, presenting data at conferences and in articles and books allows researchers to receive critical feedback from academic peers and others to test these ideas and further the field of science toward identifying the best explanations. It is important that the scientific field include researchers with diverse identities, backgrounds, and experiences so that researchers ask new questions, innovate, and problem solve more effectively.<\/p>\n<h3 class=\"import-Normal\"><strong>Hypotheses, Theories, and Laws<\/strong><\/h3>\n<p class=\"import-Normal\">Scientific investigation occurs at many levels, from investigating individual cases (e.g., \u201cWhat is causing this child\u2019s mysterious illness?\u201d) to understanding processes that affect most of us (\u201cWhat is the ideal amount of sleep for an adult?\u201d). All of these questions are important and will generate different types of testable scientific explanations. So far, we have used the term <em>hypothesis<\/em> to describe these scientific ideas about why observed phenomena are the way they are. Hypotheses are typically explanations that address a narrow set of phenomena, such as (in anthropology) a particular human population or primate species.<\/p>\n<p class=\"import-Normal\">In science, a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1098\">theory<\/a> <\/strong>is an explanation of observations that addresses a wide range of phenomena. Like hypotheses, theories also explain how or why something occurs, rely on empirical evidence, and are testable and able to be refuted. Because the term <em>theory<\/em> is often used casually outside of science, you may hear people try to dismiss a scientific claim as \u201cjust a theory.\u201d In science there are often multiple competing theories, but over time some are eliminated, leaving standing the theory or theories that best explain the most evidence. Scientific theories that have stood the test of time are thus supported by many lines of evidence and are usually reliable. Some well-tested theories accepted by most scientists include the theory of general relativity, which explains the law of gravitation and its relation to other forces, and evolutionary theory, which describes how heritable traits can change in a population over time.<\/p>\n<p class=\"import-Normal\">While scientific hypotheses and theories share many characteristics, laws are quite different. A <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1099\">law<\/a> <\/strong>is a <em>prediction<\/em> about what will happen given certain conditions, <em>not<\/em> an explanation for how or why it happens. A law is not a \u201cmature\u201d version of a theory. For example, Newton\u2019s universal law of gravity allows us to predict the gravitational force (F) between any two objects using the equation F=G(m<sub>1<\/sub>m<sub>2<\/sub>)\/r<sup>2<\/sup>, but it does not explain <em>why<\/em> gravity works. Laws are often mathematical, and some well-known laws include Newton\u2019s three laws of motion and Mendel\u2019s laws of genetic inheritance. Laws are important, and their discovery often promotes the development of theories.<\/p>\n<figure style=\"width: 290px\" class=\"wp-caption alignright\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image8.png\" alt=\"People with surprised expressions stand as a naked man runs by.\" width=\"290\" height=\"174\" \/><figcaption class=\"wp-caption-text\">Figure 1.18: Archimedes is portrayed here having just discovered his Principle of Buoyancy. The vignette is by Count Giammaria Mazzuchelli (1707\u20131765). Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Eureka!_Archimede.jpg\" target=\"_blank\">Eureka! Archimede<\/a> by <a href=\"https:\/\/www.ssplprints.com\/\" target=\"_blank\">Science and Society Piture Library Prints<\/a> is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\" target=\"_blank\">public domain<\/a>. [This image is a faithful photographic reproduction of \u201cArchimedes' Principle\u201d vignette from \"Historical and Critical Information about the Life, Inventions and Writings of Archimedes of Syracuse\" by Count Giammaria Mazzuchelli (1707\u20131765), published in Brescia, Italy in 1737.]<\/figcaption><\/figure>\n<p class=\"import-Normal\">To demonstrate how important laws can be\u2014and to show how unusual things can inspire scientific discoveries\u2014we can use the story of the ancient Greek mathematician and inventor Archimedes (Figure 1.18). Archimedes\u2019s buoyancy principle is a law that is useful for many things, including density calculations and designing ships. Purportedly, he made this discovery when he noticed the water level rise in the bathtub when he climbed in it. Realizing its importance, he is said to have shouted \u201cEureka\u201d and proceeded to run naked through the city of Syracuse. While this fun story may or may not be true, it does remain that scientific laws, alongside scientific hypotheses and theories, have a very important role in the scientific process and in generating scientific explanations about our natural world.<\/p>\n<h2 class=\"import-Normal\">Ways of Knowing: Science, Faith, and Anthropology<\/h2>\n<p class=\"import-Normal\">In anthropology, we recognize that there are many ways of knowing things. For instance, you might know that fingernails are softer than metal because as a child you accidentally stapled through your fingernail while doing an art project (a coauthor of this textbook once experienced this). This would be an example of knowledge you gained through experience. You might also know that inserting a knife into an electrical outlet is dangerous and could greatly harm you. Hopefully you learned this not from personal experience but through instruction from parents, teachers, and others in your social group. The degree to which humans rely on and benefit from the experiential knowledge of others is an important characteristic of what makes us human.<\/p>\n<p class=\"import-Normal\">A unified way of knowing that is shared by a group of people and used to explain and predict phenomena is called a<strong> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1100\">knowledge system<\/a><\/strong>. Human knowledge systems are diverse and reflect the wide range of cultures and societies throughout the world and through time.<\/p>\n<p class=\"import-Normal\">Science and religion are both knowledge systems. Yet they differ in important ways. The type of knowledge gained from science is often called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1101\">scientific understanding<\/a><\/strong>. As we have explored in the previous section, scientific understanding can change and relies on evidence and rigorous, repeated testing. Religious or spiritual ways of knowing are called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1102\">belief<\/a><\/strong>, which is different from scientific understanding because they do not require repeated testing or validation (although they can rely on observations and experiences). Instead, belief relies on trust and<strong> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1103\">faith<\/a><\/strong>.<\/p>\n<p class=\"import-Normal\">Different individuals, cultures, and societies may place more value on one type of knowing than another, although most use a combination that includes science, empiricism, and religion. In fact, Bronis\u0142aw Malinowski (1884\u20131942), an important anthropologist of the early twentieth century, concluded that all societies use both religion <em>and<\/em> science in some way or another, because they are both common ways that humans experience the world.<\/p>\n<p class=\"import-Normal\">In contemporary societies such as the United States, science and (some) religions conflict on the topic of human origins. Nearly every culture and society has a unique origin story that explains where they came from and how they came to be who they are today. These stories are often integrated into the culture\u2019s religious belief system. Many anthropologists are interested in faith-based origin stories and other beliefs because they show us how a particular group of people explain the world and their place in it. Anthropologists also value scientific understanding as the basis for how humans vary biologically and change over time. In other words, anthropologists value the multiple knowledge systems of different groups and use them to understand the human condition in a broad and inclusive way.<\/p>\n<p class=\"import-Normal\">It is also important to note that scientists often depend on the local knowledge of the people with whom they work to understand elements of the natural or physical world that science has not yet investigated. Many groups, including <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1473\">Indigenous<\/a><\/strong> peoples, know about the world through prolonged relationships with the environment. Indigenous knowledge systems\u2014specific to an Indigenous community or group\u2014are informed by their own empirical observation of a specific environment and passed down over generations.<\/p>\n<p class=\"import-Normal\">While religion and Indigenous knowledge systems may play a complementary role in helping anthropologists understand the human condition, they are distinct from science. The anthropological subdiscipline of biological anthropology is based on scientific ways of knowing about humans and human origins. In this volume, we will exclusively explore what science tells us about how humans came to be and why we are the way we are today. Therefore, you do not need to <em>believe<\/em> in evolution to master this material, because belief is not a scientific way of knowing. For this textbook, you only need to <em>understand <\/em>the scientific perspectives of evolution.<\/p>\n<p class=\"import-Normal\">Throughout our lives, each of us work to reconcile our worldview with the different ways we have of knowing things. This is part of our lifelong intellectual journey. It is also, in our opinion, one of the most exciting parts of learning. We are pleased you have joined us on this journey of knowledge about humanity and yourself!<\/p>\n<p>&nbsp;<\/p>\n<div class=\"textbox shaded\">\n<h2>Summary<\/h2>\n<p>Biological anthropology relies on the scientific method to investigate humans and other primates across time and place. While research in this field begins with careful observation, hypotheses are more closely examined with empirical evidence from excavation, fieldwork, or laboratory study. Focusing on this scientific foundation, the discipline allows anthropologists to move beyond belief and speculation to produce knowledge that is testable and continually open to challenge.<\/p>\n<p>Findings are continually debated, reviewed, and revised, ensuring that explanations improve and remain grounded in current and relevant evidence. If you have not caught on already, this textbook follows the same process, reflecting the evolving body of knowledge that is biological anthropology.<\/p>\n<h2 class=\"import-Normal\">Review Questions<\/h2>\n<ul>\n<li class=\"import-Normal\">What is science?<\/li>\n<li class=\"import-Normal\">What is the scientific method?<\/li>\n<li class=\"import-Normal\">How does science compare to other ways of knowing?<\/li>\n<\/ul>\n<\/div>\n<h2 class=\"import-Normal\">Key Terms<\/h2>\n<p class=\"import-Normal\"><strong>Empirical<\/strong>: Evidence that is verifiable by observation or experience instead of relying primarily on logic or theory.<\/p>\n<p class=\"import-Normal\"><strong>Faith<\/strong>: Complete trust or confidence in the doctrines of a religion, typically based on spiritual apprehension rather than empirical proof.<\/p>\n<p class=\"import-Normal\"><strong>Knowledge system<\/strong>: A unified way of knowing that is shared by a group of people and used to explain and predict phenomena.<\/p>\n<p class=\"import-Normal\"><strong>Participant observation<\/strong>: A research method common in cultural anthropology that involves living with, observing, and participating in the same activities as the people one studies.<\/p>\n<p class=\"import-Normal\"><strong>Scholarly peer review<\/strong>: The process whereby an author\u2019s work must pass the scrutiny of other experts in the field before being published in a journal or book.<\/p>\n<p class=\"import-Normal\"><strong>Scientific u<\/strong><strong>nderstanding<\/strong>: Knowledge accumulated by systematic scientific study, supported by rigorous testing and organized by general principles.<\/p>\n<p class=\"import-Normal\"><strong>Theory<\/strong>: An explanation of observations that typically addresses a wide range of phenomena.<\/p>\n<h2 class=\"import-Normal\">For Further Exploration<\/h2>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><a href=\"https:\/\/www.understandingscience.org\" target=\"_blank\">Understanding Science website<\/a> (a project of the University of California Museum of Paleontology.<\/p>\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #333333\">Anticole, Matt. n.d. <a href=\"https:\/\/ed.ted.com\/lessons\/what-s-the-difference-between-a-scientific-law-and-theory-matt-anticole#watch\" target=\"_blank\">\u201cWhat\u2019s the Difference between a Scientific Law and Theory?\"<\/a> TedEd Lesson. \u00a0Accessed January 28, 2023.<\/span> 28, 2023.<\/p>\n<p class=\"import-Normal\">Chan, Keith. 2021. \u201cIcebreaker Science.\u201d In <a href=\"https:\/\/explorations.americananthro.org\" target=\"_blank\"><em>Explorations<\/em><em>:<\/em><em> Lab and Activities Manual<\/em><\/a>, edited by Beth Shook, Katie Nelson, Kelsie Aguilera, and Lara Braff. Arlington, VA: American Anthropological Association.<\/p>\n<p class=\"import-Normal\">Chizmeshya, Sydney Quinn, and Katherine E. Brent. 2021. \u201cKnowing and Believing.\u201d In <a href=\"https:\/\/explorations.americananthro.org\" target=\"_blank\"><em>Explorations:<\/em> <em>Lab and Activities Manual<\/em><\/a>, edited by Beth Shook, Katie Nelson, Kelsie Aguilera, and Lara Braff. Arlington, VA: American Anthropological Association.<\/p>\n<p class=\"import-Normal\">Pfister, Anne E. 2021. \u201cScience and Belief: Just Because We Can, Doesn\u2019t Always Mean We Should.\u201d In <a href=\"https:\/\/explorations.americananthro.org\" target=\"_blank\"><em>Explorations: Lab and Activities Manual<\/em><\/a> edited by Beth Shook, Katie Nelson, Kelsie Aguilera, and Lara Braff. Arlington, VA: American Anthropological Association.<\/p>\n<h2 class=\"import-Normal\">References<\/h2>\n<p class=\"import-Normal\" style=\"text-indent: 0pt\">Binford, Leigh. 2016. <em>The El Mozote Massacre: Human Rights and Global Implications.<\/em> Revised and expanded edition. Tucson: University of Arizona Press.<\/p>\n<p class=\"import-Normal\" style=\"text-indent: 0pt\">Estrada, Alejandro, Paul A. Garber, Anthony B. Rylands, Christian Roos, Eduardo Fernandez-Duque, Anthony Di Fiore, K. Anne-Isola Nekaris, et al. 2017. \u201cImpending Extinction Crisis of the World\u2019s Primates: Why Primates Matter.\u201d <em>Science Advances<\/em> 3(229): 1\u201316.<\/p>\n<p class=\"import-Normal\" style=\"text-indent: 0pt\">Farmer, Paul. 2006. <em>AIDS and Accusation: Haiti and the Geography of Blame.<\/em> Berkeley: University of California Press.<\/p>\n<p class=\"import-Normal\" style=\"text-indent: 0pt\">Farmer, Paul, Matthew Basilico, Vanessa Kerry, Madeleine Ballard, Anne Becker, Gene Bukhman, Ophelia Dahl, et al. 2013. \u201cGlobal Health Priorities for the Early Twenty-first Century.\u201d In <em>Reimagining Global Health: An Introduction, <\/em>edited by Paul Farmer, Jim Yong Kim, Arthur Kleinman, and Matthew Basilico, 302\u2013339. Berkeley: University of California Press.<\/p>\n<p class=\"import-Normal\" style=\"text-indent: 0pt\">Kenyon, Kathleen. 1979. <em>Archaeology in the Holy Land.<\/em> New York: W.W. Norton.<\/p>\n<p class=\"import-Normal\">Malotki, Ekkehart. 1983. <em>Hopi Time: A Linguistic Analysis of the Temporal Concepts in the Hopi Languag<\/em><em>e.<\/em> Berlin: De Gruyter.<\/p>\n<p class=\"import-Normal\" style=\"text-indent: 0pt\">Mead, Margaret. 1928. <em>Coming of Age in Samoa<\/em>. Oxford: Morrow.<\/p>\n<p class=\"import-Normal\">Ochs, Elinor and Bambi Schieffelin. 2017. \u201cLanguage Socialization: An Historical Overview.\u201d In <em>Encyclopedia of Language and Education, Volume 8, <\/em>edited by Patricia Duff, 3-16. New York: Springer.<\/p>\n<p class=\"import-Normal\">Rathje, William and Cullen Murphy. 1992. \"Five Major Myths about Garbage, and Why They're Wrong.\" <em>Smithsonian<\/em> 23, no. 4: 113-122.<\/p>\n<p class=\"import-Normal\" style=\"text-indent: 0pt\">TANN. 2018. <a href=\"https:\/\/archaeonewsnet.com\/2018\/08\/mexican-anthropologists-put-face-on.html\" target=\"_blank\">\u201cMexican Anthropologists Put Face on Nearly 14,000-Year-Old Woman.\u201d<\/a> <em>Archaeology News Network<\/em>, August 19, 2018<em>. <\/em>Accessed on November 16, 2022.<\/p>\n<p class=\"import-Normal\" style=\"text-indent: 0pt\">Whorf, Benjamin. 1956. <em>Language, Thought, and Reality.<\/em> Cambridge: MIT Press.<\/p>\n<\/div>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1695_1843\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1695_1843\"><div tabindex=\"-1\"><div class=\"textbox\">Learn more about <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/about-the-authors\/\">authors and editors<\/a>,<a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/student-contributors\/\"> Hess' student contributions<\/a>, and <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/versioning-history\/\">versioning history<\/a>.<\/div>\n<div class=\"textbox textbox--learning-objectives\">\n<header class=\"textbox__header\">\n<h2 class=\"textbox__title\">Learning Objectives<\/h2>\n<\/header>\n<div class=\"textbox__content\">\n<ul>\n<li>Identify and describe the major developments in scientific thought that led to the discovery of evolutionary processes.<\/li>\n<li>Explain how natural selection works and results in evolutionary change over time.<\/li>\n<li>Explain what is meant by the \u201cModern Synthesis\u201d and its impacts on evolutionary thought.<\/li>\n<li>Discuss the teaching of human evolution in the U.S. and abroad.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<h2 class=\"__UNKNOWN__\">The Beginnings of Evolutionary Thinking<\/h2>\n<div class=\"__UNKNOWN__\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.627006530761719pt;margin-right: 3.917236328125pt;text-indent: 0pt\">Throughout our evolutionary history, humans have developed an understanding of the natural world as they interacted with and extracted resources from it. To survive, our earliest ancestors possessed an understanding of the physical environment, including weather patterns, animal behaviour, edible and medicinal plants, locations of water, and seasonal cycles. Many ancient cultures, including those of the Americas (Dunbar-Ortiz 2014), Mesopotamia, and Egypt, left writings, hieroglyphics, and stories passed down through oral tradition detailing their understanding of the natural environment, human and zoological anatomy, botany, and medical practices (Moore 1993).<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 1.209999084472656pt;margin-right: 11.6515502929688pt;text-indent: 0pt\">There are also over 2,000 years of organized thought and writing regarding <strong>evolution<\/strong>, including contributions from Greek, Roman, and Islamic scholars. Three examples of note are included here. The Greek philosopher Aristotle (384\u2013322 BCE) studied the natural world, publishing several volumes on animals based on systematic observations, rather than attributing what he observed to divine intervention, as his contemporaries were doing (Figure 2.1). Aristotle\u2019s system for the biological classification of nearly 500 species of animals was based on his own observations and dissections, interviews with specialists such as beekeepers and fishermen, and accounts of travelers. His nine book <em>History of Animals<\/em>, published in the 4th century BC (n.d.), was one of the first zoological taxonomies ever created. Aristotle\u2019s primary contribution to the classification of biological species was to recognize that natural groups are based on structure, physiology, mode of reproduction, and behaviour (Moore 1993, 39).<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 1.243003845214844pt;margin-right: 31.8323364257812pt;text-indent: 0pt\"><img class=\"aligncenter\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2023\/03\/image3-5.jpg\" alt=\"Large orange octopus on ocean floor.\" width=\"240\" height=\"321\" \/><\/p>\n<figure style=\"width: 338px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image12-4.jpg\" alt=\"Elephant half-submerged in a body of water with a ferry of human watchers behind.\" width=\"338\" height=\"231\" \/><figcaption class=\"wp-caption-text\">Figure 2.1a-b: Aristotle was the first to publish that a. octopuses can change their colours when disturbed and b. elephants use their trunks as a snorkel when crossing deep water. Credit: a. <a href=\"https:\/\/en.wikipedia.org\/wiki\/File:Octopus_macropus.jpg\" target=\"_blank\">Octopus macropus<\/a> by <a href=\"https:\/\/subnormali-team.blogspot.com\/2006_12_01_archive.html\">SUBnormali Team<\/a> (originally from <a href=\"https:\/\/it.wikipedia.org\/wiki\/Utente:Yoruno\" target=\"_blank\">Yoruno<\/a>) is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/#:~:text=You%20are%20free%20to%3A,for%20any%20purpose%2C%20even%20commercially.\" target=\"_blank\">CC-BY-SA 3.0 License<\/a>. b. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Elephant_swimming,_Botswana_(cropped).jpg\">Elephant swimming, Botswana (cropped)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/8721758@N06\" target=\"_blank\">Jorge L\u00e1scar<\/a> from Australia (uploaded by <a href=\"https:\/\/www.flickr.com\/photos\/29050464@N06\/\" target=\"_blank\">Peter D. Tillman<\/a>) is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/deed.en\" target=\"_blank\">CC BY 2.0 License<\/a>.<\/figcaption><\/figure>\n<figure style=\"width: 263px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image20-3.png\" alt=\"Rows of organisms, with plants and animals at the bottom and humans, angels, and God at top.\" width=\"263\" height=\"379\" \/><figcaption class=\"wp-caption-text\">Figure 2.2: The Great Chain of Being by Didacus Valades. Credit: <a href=\"https:\/\/commons.wikimedia.org\/w\/index.php?curid=1688250\" target=\"_blank\">Great Chain of Being<\/a> by Didacus Valades (Diego Valades 1579) and photographed by Rhetorica Christiana (via <a href=\"https:\/\/archive.org\/details\/rhetoricachristi00vala\/page\/n259\/mode\/2up\" target=\"_blank\">Getty Research<\/a>) is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\" target=\"_blank\">public domain<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 11.6515502929688pt;text-indent: 0pt\">Aristotle\u2019s <em>History of Animals<\/em> also placed animals in a hierarchy, ranking animals above plants due to what he claimed were their abilities to sense the world around them and to move. He also graded animals according to their modes of reproduction. Those giving birth to live young were placed above those who laid eggs. Warm-blooded animals ranked above invertebrates. This concept of \u201chigher\u201d and \u201clower\u201d organisms was expanded upon by scholars in the Medieval period to form the <em>Scala Naturae<\/em> (Latin for \u201cladder of being\u201d). This \u201cGreat Chain of Being,\u201d depicting a hierarchy of beings with God at the top and minerals at the bottom (Figure 2.2), was thought by medieval Christians to have been decreed by God; in this Great Chain, humans were placed closer to God than other species. Aristotle\u2019s works were rediscovered by Islamic scholars in the ninth century and translated into Arabic, Syriac, Persian, and later into Latin, becoming part of university curriculum in 13th-century Europe (Lindberg 1992), allowing Aristotle\u2019s works and ideas to influence other thinkers for 2,000 years.<\/p>\n<figure style=\"width: 251px\" class=\"wp-caption alignright\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image8-5.jpg\" alt=\"A person leading a giraffe on a leash, with text written in Arabic below.\" width=\"251\" height=\"375\" \/><figcaption class=\"wp-caption-text\">Figure 2.3: An image from Kit\u0101b al-\u1e25ayaw\u0101n (Book of the Animals) by Al-Jahiz. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Al-Jahiz.jpg\" target=\"_blank\">Al-Jahiz<\/a> by Al-Jahiz [in <a href=\"https:\/\/themuslimtimes.info\/2017\/02\/25\/al-jahizs-book-of-animals-the-transcendent-value-of-disgust\/\" target=\"_blank\">Kit\u0101b al-\u1e25ayaw\u0101n<\/a> (Book of the Animals), 15th century] is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\" target=\"_blank\">public domain<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 12.08837890625pt;text-indent: 0pt\">Science also owes a debt to many Arabic scholars. One such Islamic scholar and writer, who built upon the ideas of Aristotle, was Ab\u016b \u02bfUthman \u02bfAmr ibn Ba\u1e25r al-Kin\u0101n\u012b al-Ba\u1e63r\u012b \/ al-J\u0101\u1e25i\u1e93, known as Al-Jahiz (776\u2013868 CE), who authored over 200 books (El-Zaher 2018; Figure 2.3). His most well-known work was the seven-volume <em>Kitab al-Hayawan<\/em> or <em>Book of Animals<\/em>, in which he described over 350 species in zoological detail. Importantly, Al-Jahiz introduced the idea and mechanisms of biological evolution 1,000 years before Darwin proposed the concept of <strong>natural selection<\/strong> in 1859 (Love 2020). For instance, Al-Jahiz wrote about the struggle for existence, the transformation of species over time, and environmental factors that influence the process, all ideas that were later espoused by western European scientists in the 19th century. Al-Jahiz wrote:<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.891006pt;margin-right: 12.0884pt;text-indent: 0.648994pt;text-align: left;padding-left: 40px\">Animals engage in a struggle for existing, and for resources, to avoid being eaten, and to breed. Environmental factors influence organisms to develop new characteristics to ensure survival, thus transforming them into new species. Animals that survive to breed can pass on their successful characteristics to their offspring. [Masood 2009]<\/p>\n<figure style=\"width: 335px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image9-7.png\" alt=\"A person with a full beard and turban looks into the distance.\" width=\"335\" height=\"389\" \/><figcaption class=\"wp-caption-text\">Figure 2.4: Drawing of Ibn al-Haytham. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Ibn_al-Haytham.png\" target=\"_blank\">Ibn al-Haytham<\/a> by Sopianwar is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\" target=\"_blank\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.891006469726562pt;margin-right: 12.08837890625pt;text-indent: 0.648994445800781pt\">Another important early Islamic scientist is Ibn al-Haytham (965\u20131040), a 10th-century Islamic scholar who contributed a great deal to our understanding of optics and how human vision works (Figure 2.4; Lindberg 1992, 177\u2013180). Born in what is now Iraq, al-Haytham was a scholar of many disciplines, including mathematics, physics, mechanics, astronomy, philosophy, and medicine. He authored some 200 books in his lifetime and was an expert on Aristotle\u2019s natural philosophy, logic, and metaphysics. In relation to evolution, al-Haytham\u2019s methodology of investigation\u2014specifically, using experiments to verify theory\u2014is similar to what later became known as the modern scientific method. He is most famous for discovering the laws of reflection and refraction over 1,000 years ago and inventing the camera obscura, which was incredibly important for the eventual development of photography. His work is credited for its influence on astronomy, mathematics, and optics, inspiring Galileo, Johannes Kepler, and Sir Isaac Newton (Tasci 2020). As an inspirational scientific figure, al-Haytham was celebrated in 2016 by UNESCO as a trailblazer and the founder of modern optics (Figure 2.5). An International Year of Light was named in his honor and a scholarly conference on his contributions was held to coincide with the 1,000th anniversary of the publication of his <em>Kit\u0101b al-Man\u0101\u1e93ir<\/em> (Book of Optics; UNESCO.org 2015).<\/p>\n<figure style=\"width: 239px\" class=\"wp-caption alignright\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image16-2.jpg\" alt=\"Labeled diagram of the eye and optic nerves.\" width=\"239\" height=\"399\" \/><figcaption class=\"wp-caption-text\">Figure 2.5: Diagram of the Human Eye by Ibn al-Haytham. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:I.A._Haitham,_Diagram_of_the_eye,_16th_century_Wellcome_L0011969.jpg\" target=\"_blank\">Diagram of the eye<\/a> by Ibn Al [Alhazen] Haitham (16th Century) has been modified (cropped) and is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/legalcode\" target=\"_blank\">CC BY 4.0 License<\/a>. This image is available from <a href=\"https:\/\/wellcomeimages.org\/\" target=\"_blank\">Wellcome Images<\/a> 3044 (under the photo number L0011969).<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0.891006469726562pt;margin-right: 12.08837890625pt;text-indent: 0.648994445800781pt\">The writings of these Islamic scholars as well as similar scientific texts from other cultures were unknown to or unacknowledged by Western scientists until recently. Fortunately, many science teachers are now incorporating this content into their classes (Love 2020).<\/p>\n<h2 class=\"import-Normal\" style=\"background-color: transparent;margin-left: 1.364006042480469pt;margin-right: 0pt;text-indent: 0pt\">Western European Evolutionary Thought<\/h2>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.836006164550781pt;margin-right: 0.0257568359375pt;text-indent: 0pt\">Although there have been many different scientific traditions throughout world history, a new global discourse around science emerged in Western Europe in the 19th century. Europeans pointed to the continuing expansion of their colonial power\u2014as well as their military and technological success\u2014as evidence of the efficacy of Western science, which came to dominate on a global scale (Elshakry 2010). The movement toward a global science centred in Western Europe began with formulation of the <strong>Scientific Method<\/strong>.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0.0257568359375pt;text-indent: 0pt\">The Scientific Method was first codified by Francis Bacon (1561\u20131626), an English politician who was likely influenced by the methods of inquiry established by Ibn al-Haytham centuries prior (Tbakhi &amp; Amr 2007). Bacon has been called the founder of <strong>empiricism<\/strong> for proposing a system for weighing the truthfulness of knowledge based solely on inductive reasoning and careful observations of natural phenomena. Ironically, he died as a result of trying to scientifically observe the effects of cold on the putrefaction of meat. On a journey out of London, he purchased a chicken and stuffed it with snow for observation, catching a chill in the process. One week later, he died of bronchitis (Urbach, Quinton, &amp; Lea 2023).<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0.0257568359375pt;text-indent: 0pt\">The second important development with regard to evolution was the concept of a <strong>species<\/strong>. John Ray (1627\u20131705), an English parson and naturalist, was the first person to publish a biological definition of species in his <em>Historia Plantarum<\/em> (<em>History of Plants),<\/em> a three volume work published in 1686, 1688, and 1704<em>. <\/em>Ray defined a <em>species<\/em> as a group of morphologically similar organisms arising from a common ancestor. However, we now define a species as a group of similar organisms capable of producing fertile offspring. In keeping with the scientific method, Ray classified plants according to similarities and differences that emerged from observation. He claimed that any seed from the same plant was the same species, even if it had slightly different traits.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.836006164550781pt;margin-right: 4.403076171875pt;text-indent: 0pt\">The modern period of biological classification began with the work of Carl von Linne (\u201cCarolus Linnaeus\u201d) (1707\u20131778), a Swedish scientist who laid the foundations for the modern scheme of taxonomy used today. He established the system of <strong>binomial nomenclature<\/strong>, in which a species of animal or plant receives a name consisting of two terms: the first term identifies the genus to which it belongs and the second term identifies the species. His original <em>Systema<\/em> <em>Naturae<\/em>, published in 1736, went through several editions. By the tenth edition in 1758, mammals incorporated primates, including apes and humans, and the term <em>Homo sapiens <\/em>was introduced to signify the latter (Paterlini 2007).<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.495002746582031pt;margin-right: 4.97509765625pt;text-indent: 0pt\">Georges-Louis Leclerc, Comte de Buffon (1707\u20131788), was a prominent French naturalist whose work influenced prominent scientists in the second half of the 18th century. Buffon's idea that species change over time became a cornerstone of modern evolutionary theory. His technique of comparing similar structures across different species, called <strong>comparative anatomy<\/strong>, is still in use today in the study of evolution. He published 36 volumes of <em>Histoire<\/em> <em>Naturelle<\/em> during his lifetime and heavily influenced two prominent French thinkers who were to have significant impacts on our understanding of evolution, Georges Cuvier and Jean-Baptiste Lamarck.<\/p>\n<figure style=\"width: 455px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image23-2.jpg\" alt=\"Historic painting of person with short wavy hair next to drawing of a mastodon skeleton.\" width=\"455\" height=\"302\" \/><figcaption class=\"wp-caption-text\">Figure 2.6: Cuvier with one of his drawings of a fossil quadruped. Credit: Cuvier and a fossil quadruped original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\" target=\"_blank\">CC BY-NC-SA 4.0 License<\/a>. [Includes <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Georges_Cuvier_3.jpg\" target=\"_blank\">Georges Cuvier 3<\/a> by <a href=\"https:\/\/en.wikipedia.org\/wiki\/Fran%C3%A7ois-Andr%C3%A9_Vincent\" target=\"_blank\">Fran\u00e7ois-Andr\u00e9 Vincent<\/a> (artist), <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\" target=\"_blank\">public domain<\/a>; <a href=\"https:\/\/freesvg.org\/mammoth-skeleton\" target=\"_blank\">Mammoth skeleton<\/a> in <a href=\"https:\/\/freesvg.org\/by\/OpenClipart\" target=\"_blank\">OpenClipart<\/a>, <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/cc0\/\" target=\"_blank\">public domain (CC0)<\/a>.]<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.594001770019531pt;margin-right: 1.4913330078125pt;text-indent: 0pt\">Georges Cuvier (1769\u20131832) was a paleontologist and comparative anatomist (Figure 2.6). One of his first major contributions to the field of evolution was proof that some species had become <strong>extinct <\/strong>through detailed and comprehensive analyses of large fossil quadrupeds (Moore 1993, 111). The idea of extinction was not new, but it was challenging to demonstrate if a fossil species was truly extinct or still had living relatives elsewhere. It was also challenging in that it ran counter to religious beliefs of the time. The Bible\u2019s Book of Genesis was interpreted as saying that all species had been created by God in the seven days it took to create the world and that all created species have survived to this day. Extinction was interpreted as implying imperfection, suggesting God\u2019s work was flawed. Also, given that the Earth was calculated to have been created in 4004 B.C.E., based on biblical genealogies, there would not have been enough time for species to disappear (Moore 1993, 112).<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 1.4913330078125pt;text-indent: 0pt\">Cuvier was so knowledgeable in this field that he became famous for his ability to reconstruct what an extinct animal looked like from fragmentary remains. He demonstrated that fossil mammoths differed from similar living creatures, such as elephants. His many examples of fossils telling the stories of animals that lived and then disappeared were taken as incontrovertible proof of extinctions (PBS 2001). Where Cuvier went awry was his hypothesis of how extinction worked and its causes. As part of his study of comparative anatomy, Cuvier made observations of stratified layers of rock, or sediment, each containing different species. From this, he drew conclusions that species were \u201cfixed\u201d and did not evolve, but then went extinct, and that different assemblages of fossils occurred at different times in the past, as evidenced by the sedimentary layers (Moore 1993, 118). Cuvier explained this through a theory of <strong>catastrophism<\/strong>, which stated that successive catastrophic deluges (akin to Biblical floods) swept over parts of the Earth periodically, exterminating all life. When the waters receded from a particular region, lifeforms from unaffected regions would repopulate the areas that were destroyed, giving rise to a new layer of species that looked different from the layer below it. This theory implied that species were fixed in place and did not evolve and that the Earth was young. In fact, Cuvier postulated that the last catastrophe was a deluge he believed occurred five to six thousand years ago, paving the way for the advent of humans (Moore 1993, 118). Cuvier\u2019s catastrophism became part of an ongoing and vociferous debate between two schools of geology. The catastrophists believed the present state of the earth was the consequence of a series of violent catastrophes of short duration, while the uniformitarians thought it was the result of slow acting geological forces that continue to shape the earth.<\/p>\n<figure style=\"width: 379px\" class=\"wp-caption alignright\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image13-2.jpg\" alt=\"Horizontal layers of rock rest on vertical layers of rock.\" width=\"379\" height=\"303\" \/><figcaption class=\"wp-caption-text\">Figure 2.7: Siccar Point, Aberdeen, UK. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Siccar_Point.jpg\" target=\"_blank\">Siccar Point<\/a> by <a href=\"https:\/\/www.geograph.org.uk\/profile\/139\" target=\"_blank\">Anne Burgess<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\" target=\"_blank\">CC BY-SA 2.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.495002746582031pt;margin-right: 1.47552490234375pt;text-indent: 0pt\">James Hutton (1726\u20131797) was one prominent proponent of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_830\">uniformitarianism<\/a><\/strong>. Based on evidence he found at sites in his native Scotland, Hutton argued that the Earth was much older than previously thought. Examining the geology of Siccar Point, a cliff site on the eastern coast of Scotland (Figure 2.7), Hutton concluded that the intersection of the vertical and horizontal rocks represented a gap in time of many millions of years, during which the lower rocks had been deformed and eroded before the upper layers were deposited on top. From this, Hutton argued sediments are deposited primarily in the oceans, where they become strata, or layers of sedimentary rock. Volcanic action uplifts these strata to form mountains, which are then subject to erosion from rain, rivers, and wind, returning sediment to the oceans (Moore 1993, 121). Hutton\u2019s <em>Theory of the Earth <\/em>(1788) demanded vast periods of time (known as \u201cdeep time\u201d) for such slow-working forces to shape the earth. At the time, he was heavily criticized for this view, as it contradicted the biblical version of the history of creation.<\/p>\n<figure style=\"width: 391px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image18-3.jpg\" alt=\"A cross-section of a volcanic eruption showing different types of rock that make up the volcano.\" width=\"391\" height=\"249\" \/><figcaption class=\"wp-caption-text\">Figure 2.8: The frontispiece from Charles Lyell's Principles of Geology (2nd American edition, 1857), showing the origins of different rock types. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Lyell_Principles_frontispiece.jpg\" target=\"_blank\">Lyell Principles frontispiece<\/a> by Charles Lyell (Principles of Geology, 2nd American edition, 1857) is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\" target=\"_blank\">public domain<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.495002746582031pt;margin-right: 1.47552490234375pt;text-indent: 0pt\">Another Scotsman, who was to become a highly influential geologist and a close friend of Darwin, was Charles Lyell (1797\u20131875). Lyell was originally a lawyer who began his studies of Geology at Oxford under the tutelage of catastrophist William Buckland, from whom he diverged when Buckland tried to find physical evidence of Noah\u2019s flood from the Christian Bible. Lyell was instead intent on establishing geology as a science based on observation. Building upon Hutton\u2019s ideas (published 50 years earlier), Lyell traveled throughout Europe, documenting evidence of uniformitarianism. During his travels, he catalogued evidence of sea level rise and fall and of volcanoes positioned atop much older rocks. He also found evidence of valleys formed through erosion, mountains resulting from earthquakes, and volcanic eruptions that had been witnessed or documented in the past (University of California Berkeley Museum of Paleontology n.d.). Lyell also espoused the principle that \u201crocks and strata (layers of rock) increase in age the further down they are in a geological sequence. Barring obvious upheavals or other evidence of disturbance, the same principle must apply to any fossils contained within the rock. The lower down in a sequence of rocks a fossil is, the older it is likely to be (Wood 2005, 12).\u201d<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0.495002746582031pt;margin-right: 1.47552490234375pt;text-indent: 0pt\">Lyell published the first edition of his three-volume <em>Principles of Geology <\/em>in 1830\u20131833 (Figure 2.8). It established geology as a science, underwent constant revisions as new scientific evidence was discovered, and was published in 12 editions during Lyell\u2019s lifetime. In it, he espoused the key concept of uniformitarianism\u2014that \"the present is the key to the past.\u201d What this meant was that geological remains from the distant past can be explained by reference to geological processes now in operation and directly observable.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 1.83465576171875pt;text-indent: 0pt\">Jean-Baptiste Lamarck (1744\u20131829) was the first Western scientist to propose a mechanism explaining why and how traits changed in species over time, as well as to recognize the importance of the physical environment in acting on and shaping physical characteristics. Lamarck\u2019s view of how and why species changed through time, known as the \u201cTheory of Inheritance of Acquired Characteristics,\u201d was first presented in the introductory lecture to students in his invertebrate zoology class at the Museum of Natural History in Paris in 1802 (Burkhardt 2013). It was based on the idea that as animals adapted to their environments through the use and disuse of characteristics, their adaptations were passed on to their offspring through reproduction (Figure 2.9). Lamarck was right about the environment having an influence on characteristics of species, as well as about variations being passed on through reproduction. He simply had the mechanism wrong.<\/p>\n<p><img class=\"aligncenter\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image14-5.png\" alt=\"Giraffes with necks of different heights reach to eat leaves.\" width=\"419\" height=\"244\" \/><\/p>\n<figure style=\"width: 404px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image11-7.png\" alt=\"Illustration of three giraffes with necks of different heights.\" width=\"404\" height=\"391\" \/><figcaption class=\"wp-caption-text\">Figure 2.9a-b: Inheritance of Acquired Characteristics and Natural Selection. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-3\/\" target=\"_blank\">Lamarckian Evolution (Figure 4.2A and 4.2B)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 1.86676025390625pt;text-indent: 0pt\">Lamarck\u2019s theory involved a three-step process. Step one involves an animal experiencing a radical change in its environment. Step two is the animal (either individual or species) responding with a new kind of behaviour. Step three is how the behavioural change results in morphological (meaning physical) changes to the animal that are successfully passed on to subsequent generations (Ward 2018, 8). Lamarck\u2019s most famous example was the proposition that giraffes actively stretched their necks to reach leaves on tall trees to eat. Over their lifetimes, the continuation of this habit resulted in gradual lengthening of the neck. These longer necks were then passed on to their offspring. Lamarck's theory was disproved when evolutionary biologist August Weismann published the results of an experiment involving mice (Figure 2.10). Weismann amputated the tails of 68 mice and then successively bred five generations of them, removing the tails of all offspring in each generation, eventually producing 901 mice, all of whom had perfectly healthy long tails in spite of having parents whose tails were missing (Weismann 1889).<\/p>\n<figure style=\"width: 551px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image6-5.png\" alt=\"Mice with cut-off ails breed healthy offspring with full length tails.\" width=\"551\" height=\"385\" \/><figcaption class=\"wp-caption-text\">Figure 2.10: Weismann\u2019s mouse-tail experiment showing that offspring do not inherit traits that the parents acquired during their lifetimes. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-3\/\" target=\"_blank\">Weismann\u2019s mouse-tail experiment (Figure 4.3)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.527999877929688pt;margin-right: 0.20892333984375pt;text-indent: 0pt\">How giraffes actually ended up with long necks is a different story. In an environment where the food supply is higher off the ground, and perhaps less available to competing species, giraffes who happened to have slightly longer necks (due to random individual variation and genetic mutation) would be more likely to survive. These giraffes would then be able to reproduce, passing along the slight variation in neck length that would allow their offspring to do the same. Over time, individuals with longer necks would be overrepresented in the population, and neck lengths overall would increase among giraffes. Unfortunately, Lamarck\u2019s ideas challenged the scientific establishment of the time and were rejected. He was discredited and harassed \u201cto the point of loss of money, reputation, and then health\u201d (Ward 2018, 9).<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.527999877929688pt;margin-right: 0.4715576171875pt;text-indent: 0pt\">The final piece in the evolutionary puzzle leading up to the theory of natural selection was put forth by Thomas Malthus (1766\u20131834), who published <em>A<\/em><em>n Essay on Population <\/em>in 1798. Malthus lived in England during the time of the Industrial Revolution. It was a time of great poverty and misery when many people migrated from the countryside to squalid, disease-ridden cities to work extremely long hours in dangerous conditions in factories, coal mines, and other industrial workplaces. Birth rates were high and starvation and disease were rampant. Malthus struggled to explain why. His answer was basically the idea of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1788\">carrying capacity<\/a><\/strong>, an ecological concept still in use today. Malthus suggested the rate of population growth exceeded the rate of increase of the human food supply. In other words, people were outgrowing the available food crops. He also suggested that populations of animals and plants were naturally constrained by the food supply, resulting in reductions in population in times of scarcity, \u201crestraining them within the prescribed bounds\u201d (Moore 1993, 147). But, despite significant challenges, some individuals always survived. This was the key to later understandings of evolutionary change in species over time.<\/p>\n<h2 class=\"import-Normal\" style=\"background-color: transparent;margin-left: 1.331001281738281pt;margin-right: 0pt;text-indent: 0pt\">The Journey to Natural Selection<\/h2>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.527999877929688pt;margin-right: 7.171630859375pt;text-indent: 0pt\">In Western European thought, the individual most closely associated with evolution is Charles Darwin (1809\u20131882). However, as one can see from the individuals and ideas presented in the prior section, he was not the first person to explore evolution and how it might work. In fact, Darwin built upon and synthesized many of the ideas\u2014from geology to biology, ecology, and economy\u2014discussed above. He was simply in the right place at the right time. If he had not worked out his ideas when he did, someone else would have. As a matter of fact, as noted below, someone else did, forcing Darwin to publicly reveal his theory.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 7.171630859375pt;text-indent: 0pt\">Darwin continued his observations and experiments during his formal education, culminating in his graduation from Cambridge in 1831, at which point he was invited to become a gentleman naturalist for a British Royal Navy surveying mission of the globe aboard the H.M.S. <em>Beagle<\/em>. It is worth noting that Darwin was only 22 years old and the captain\u2019s third choice for the position (Costa 2017), but he proved extremely curious and methodical. The mission departed in December of 1831 and returned five years later (Figure 2.11). During this time, Darwin produced copious notebooks, observations, drawings, and reflections on the natural phenomena he encountered and the experiments he performed.<\/p>\n<figure style=\"width: 780px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image22-5.png\" alt=\"The voyage of the Beagle throughout the world.\" width=\"780\" height=\"329\" \/><figcaption class=\"wp-caption-text\">Figure 2.11: Map of the voyage of the H.M.S. Beagle. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available.<\/a> Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Voyage_of_the_Beagle-de.svg\" target=\"_blank\">Voyage of the Beagle-de<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Succu\" target=\"_blank\">Succu<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 3.4952392578125pt;text-indent: 0pt\">Discussing all of Darwin\u2019s work aboard the <em>Beagle <\/em>is beyond the scope of this chapter, but his primary interests were in cataloguing new varieties of plant and animal life and examining the geology of the places the ship made landfall. Part of Darwin\u2019s success with regard to both ventures was due to his extreme seasickness, which began before the ship even left Plymouth Harbour. It never let up, encouraging Darwin to go ashore at every available opportunity. \u201cIn fact, of the nearly five years of the voyage, Darwin was actually on board the ship for just a year and a half altogether\u201d (Costa 2017, 18).<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.527999877929688pt;margin-right: 4.93707275390625pt;text-indent: 0pt\">During the voyage, the young Darwin tried to make sense of what he saw through the lens of the scientific paradigms he held when he left England, but he continually made observations that challenged these paradigms. For example, while the <em>Beagle<\/em> crewmen were charting the coast of Argentina, Darwin conducted fieldwork on land. There he observed species that were new to him, like armadillos. He also collected fossils, including those of extinct armadillos. Meaning, he had found both <strong>extant <\/strong>and extinct members of the same species in the same geographic location, which challenged the theory of catastrophism put forth by Cuvier, who argued that each variant of an animal, living or extinct, was its own distinct species (Moore 1993, 144). Darwin also observed geographic variation in the same species all along the east coast of South America, from Brazil to the southern tip of Argentina. He noted that some species were found in multiple localities and differed from place to place. Those living closer to each other exhibited only slight variations, while those living further apart might be catalogued as entirely different species if one did not know better.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.693000793457031pt;margin-right: 14.136962890625pt;text-indent: 0pt\">He made similar observations in the Galapagos Islands located off the northwest coast of Ecuador, with regard to giant tortoises and finches (Figure 2.12). A local resident of the islands explained to Darwin that each island had its own variety of tortoise and that locals could discern which island a tortoise came from simply by looking at it. Darwin noted other such examples in both plants and animals, meaning geographic variation was occurring on separate, neighbouring islands.<\/p>\n<figure style=\"width: 684px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image15-4.jpg\" alt=\"Hood Island tortoises have saddle-backed shells; Isabella Island, dome-shaped; Pinta Island, intermediate.\" width=\"684\" height=\"528\" \/><figcaption class=\"wp-caption-text\">Figure 2.12: Variation in giant tortoises in the Galapagos Islands. Credit: Giant Tortoises of the Galapagos Islands original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Mary Nelson and Katie Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0.67529296875pt;text-indent: 0pt\">Prevailing views of time argued that variations in living species, and even the fossil armadillos and the living armadillos, were the result of separate creation events. According to this view, each variation, no matter how slight, was a different species. Challenging these ideas would mean challenging not only catastrophism, but the <strong>Fixity of Species<\/strong> and other well-accepted ideas of the time. Darwin was aware that he was a young, unestablished naturalist. He was also aware of the ruin that befell Lamarck when his theories were rejected. Lastly, Lyell, who was a good friend of Darwin\u2019s, rejected evolution altogether. It is no wonder that Darwin published a great deal about the geological and fossil data he collected when he returned from the voyage, but not his early hypotheses about evolution.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.627006530761719pt;margin-right: 0pt;text-indent: 0pt\">Upon Darwin\u2019s return to England, it took another twenty years of data collection and experimentation before he was ready to share his conclusions about evolution. Much of this work was conducted at Down House, his home of forty years, where he performed all sorts of experiments that laid the groundwork for his ideas about evolution. Darwin\u2019s home was his laboratory, and he engaged the help of his children, neighbours, friends, and servants in collecting, dissecting, and experimenting. At one point in the 1850s, sheets of moistened paper covered with frogs eggs lined the hallways of the house, while flocks of sixteen different pigeon breeds cooed outside, glass jars filled with salt water and floating seeds filled the cellar, and the smell of dissected pigeon skeletons pervaded the air inside the house. There were also ongoing experiments in the yard, including piles of dissected flowers, beekeeping, and fenced-off plots of land where seedlings were under study. Darwin was a keen experimental scientist, observer, and a prolific writer and presenter of scientific papers. He regarded his work as \u201cone long argument\u201d that never really ended. In fact, Darwin published ten books after <em>On the Origin of Species<\/em>, addressing such far-ranging topics as animal behaviour, orchids, and domestication, among others (Costa 2017).<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.627006530761719pt;margin-right: 0pt;text-indent: 0pt\">Darwin may not have published <em>Origins<\/em> in 1859 had it not been for receiving a paper in June of 1858 from Alfred Russel Wallace, an English naturalist working in Malaysia, espousing the same ideas. Wallace had sent the paper to Darwin asking if it was worthy of publication and requesting he forward it to Lyell and the English botanist, Joseph Hooker. Darwin wrote to Lyell and Hooker about Wallace\u2019s paper, entitled <em>On the Tendency of Varieties to Depart Indefinitely from the Original Type<\/em>. In recognition that both Wallace and Darwin had arrived at the same discovery, a \u201cjoint\u201d paper composed of four parts (none of them actually coauthored) was read to the Linnaean Society by Lyell, then secretary of the Society, on July 1, 1858, and published on August 20. Darwin published <em>On the Origin of Species <\/em>15 months later. (The original composite paper read before the Linnaean society is available to read for free from the Alfred Russell Wallace Website, on the <a href=\"https:\/\/wallacefund.myspecies.info\/content\/1858-darwin-wallace-paper\" target=\"_blank\">1858 Darwin-Wallace paper<\/a> page.)<\/p>\n<h3 class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.726005554199219pt;margin-right: 0pt;text-indent: 0pt\"><strong>The Mechanism of Natural Selection <\/strong><\/h3>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.693000793457031pt;margin-right: 4.15203857421875pt;text-indent: 0pt\">Let us take a moment here to explore the mechanism of natural selection in more detail. Before we begin, it is important to recognize that Darwin defined evolution as descent with modification, by which he meant that species share a common ancestor yet change over time, giving rise to new species. Descent with modification refers to the fact that offspring from two parents look different from each of their parents, and from each other, meaning they descend with slight differences (\u201cmodifications\u201d). If you have ever observed a litter of puppies or a field of flowers and stopped to examine each individual closely, you have seen that each differs from the next, and none look exactly like their parents. These variations are random, not specific, and may or may not be present in the following generations.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.693000793457031pt;margin-right: 4.15203857421875pt;text-indent: 0pt\">Darwin struggled to explain why some slight differences were preserved over time, while others were not. He turned to what he knew of animal breeding (<strong>artificial selection<\/strong>) for an explanation (Richards 1998). Darwin bred different breeds of pigeons at Down House, carefully documenting phenotypic differences across generations, including slight anatomical variations he observed through dissection. He also grew and crossbred species of flowers and dissected those too. Darwin was also very fond of hunting and of hunting dogs. In an early draft of his theory on speciation, he used greyhounds as an example of adaptation and selection, \u201cnoting how its every bone and muscle, instinct and habit, were fitted to run down hare (rabbits) (University of Cambridge n.d.).\u201d In each case of plant and animal breeding Darwin observed, he noted that humans were selecting variants in each generation that had characteristics humans desired (i.e., sweetness of fruits, colours of flowers, fur type and colour of animals). Breeders then continually bred plants and animals with the desired variants, over and over again. These small changes added up over time to create new species of plants and breeds of animals. Darwin also noted that artificial selection does not necessarily render plants or animals better adapted to their original environments. The characteristics humans desire often result in plants less likely to survive in the wild and animals more likely to suffer from certain behavioural or health problems. One has only to examine high rates of hip dysplasia in several modern breeds of dogs to observe what Darwin was referring to.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.693000793457031pt;margin-right: 4.15203857421875pt;text-indent: 0pt\">From his studies of artificial selection, Darwin drew the conclusion that nature also acts upon variations among members of the same species. Instead of human intervention, the forces of nature, such as heat, cold, predation, disease, and now climate change, determine which offspring, with which variants, survive and reproduce. These individuals then pass down these favourable variants to their own offspring. In this way, nature selects for traits that are beneficial within a particular environment and selects against traits that are disadvantageous within a particular environment. Over many generations, populations of a species become more and more adapted (or, in evolutionary terms, \u201cfit\u201d) for their specific environments. Darwin named this process natural selection.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.693000793457031pt;margin-right: 4.15203857421875pt;text-indent: 0pt\">This theory explained the variations in tortoises Darwin had observed years earlier in the Galapagos Islands (see Figure 2.12). Tortoises who lived on larger islands with lush vegetation to feed on were larger than those on smaller islands. They also had shorter necks and dome-shaped shells as their food was close to the ground. Tortoises on smaller, drier islands fed on cacti, which grew much taller. These tortoises had longer necks, longer front legs, and saddle-shaped shells, which allowed them to successfully stretch to reach the edible cactus pads that grew on the tops of the plants. How did these observable differences in the two tortoise populations emerge? Darwin would argue that, over time, small, random variations in the tortoises were differentially selected for by the distinct natural environments on different islands.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.693000793457031pt;margin-right: 4.15203857421875pt;text-indent: 0pt\">In addition to the biogeographical evidence Darwin offered from his research aboard the <em>Beagle<\/em>, as well as the evidence he documented from the artificial selection of plants and animals, he also relied, where possible, on fossil evidence. One example, mentioned above, were the fossil findings of extinct armadillos in Argentina in the same locations as living armadillos. Unfortunately, as Darwin himself noted, the geological record was incomplete, most often missing the transitional fossil forms that bridge extinct and living species. That issue has since been resolved with scientific research in geochronology and paleontology, among other fields. It is now well-established that life is far more ancient than was believed in Darwin\u2019s time and that these ancient forms of life were the ancestors to all life on this planet (Kutschera &amp; Niklas 2004).<\/p>\n<h2 class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\">What Darwin was Missing<\/h2>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.527999877929688pt;margin-right: 2.886962890625pt;text-indent: 0pt\">Although the theory of evolution by natural selection gained traction in scientific circles in the decades after Darwin\u2019s publication of <em>Origins<\/em>, he was never able to discover the mechanisms that caused variation within members of the same species or the means by which traits were inherited. This began later in 1892 with the publication of <em>The Germ-Plasm: A Theory of Heredity<\/em> by August Weismann, the same Weismann of the mouse tail experiment presented earlier in this chapter. In his book, Weissman proposed a theory of germ-plasm, which was a precursor to the later discovery and understanding of DNA. Weismann specialized in cytology, a branch of biology devoted to understanding the function of plant and animal cells. Germ-plasm, he proposed, was a substance in the germ cells (what we would call gametes, or sex cells, today) that carried hereditary information. He predicted that an offspring inherits half of its germ-plasm from each of its parents, and claimed that other cells (e.g. somatic, or body, cells) could not transmit genetic information from parents to offspring. This thereby erased the possibility that acquired traits (which he argued resided in somatic cells) could be inherited (Zou 2015). This contribution to evolutionary theory was an important step toward understanding genetic inheritance, but a connection between genetics and evolution was still lacking.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 2.886962890625pt;text-indent: 0pt\">A series of lectures by a deceased Augustinian monk named Gregor Mendel (1822\u20131884), originally published in 1865, changed that perspective (Moore 1993, 285). Although Darwin was unknown to Mendel, he began a series of experiments with pea plants shortly after the publication of Darwin\u2019s <em>Origins<\/em>, aiming to add to evolutionary understandings of heredity. As Mendel bred different generations of pea plants that had differences in seed shape and colour, pod shape and colour, flower position, and stem length, he documented consistent expression of some variations over others in subsequent generations. He meticulously documented the statistics of each crossing of plants and the percentages of <strong>phenotypes<\/strong> that resulted, eventually discovering the concept of dominance and recessiveness of characteristics, as will be seen in chapter 3. The recognition of the importance of Mendel\u2019s work began with its rediscovery by Hugo de Vries and Carl Correns, both of whom were working on hypotheses regarding heredity in plants and had arrived at conclusions similar to Mendel\u2019s. Both published papers supporting Mendel\u2019s conclusions in 1900 (Moore 1993). Research into the inheritance of characteristics continued through the next three decades, and by the close of the 1930s, no major scientific questions remained regarding the transmission of heredity through <strong>genes<\/strong>, although what genes did and what chemicals they were made of were still under investigation.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 2.886962890625pt;text-indent: 0pt\">The <strong>Modern Synthesis <\/strong>refers to the merging of Mendelian genetics with Darwinian evolution that took place between 1930 and 1950. The basic principles of the synthetic theory were influenced by scientists working in many different fields, including genetics, zoology, biology, paleontology, botany, and statistics. Although there were differences of opinion among them, evolution came to be defined as changes in allele frequencies within populations. Genetic mutations, changes in the genetic code that are the original source of variation in every living thing, were believed to be random, the sources of phenotypic variation, and transmitted through sexual reproduction. These assertions were supported by a growing body of field and laboratory research, as well as new work in mathematics in the field of population genetics that defined evolution as numerical changes in gene frequencies within an interbreeding population from one generation to the next (Corning 2020). These changes in gene frequencies were argued to be the result of natural selection, mutation, migration (<strong>gene flow<\/strong>), and <strong>genetic drift<\/strong>, or random chance. Empirical research and mathematics demonstrated that very small selective forces acting over a relatively long time were able to generate substantial evolutionary change, including speciation (Plutynski 2009). Thus, the Modern Synthesis encompassed both <strong>microevolution<\/strong>, which refers to changes in gene frequencies between generations within a population, and <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1507\">macroevolution<\/a><\/strong>, longer-term changes in a population that can eventually result in speciation, wherein individuals from different populations are no longer able to successfully interbreed and produce viable offspring.<\/p>\n<figure style=\"width: 267px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image10-2.jpg\" alt=\"A white man with short hair dressed in a white shirt and dark tie.\" width=\"267\" height=\"355\" \/><figcaption class=\"wp-caption-text\"><em>Figure 2.13: Theodosius Dobzhansky (1943). Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Dobzhansky_no_Brasil_em_1943.jpg\" target=\"_blank\">Dobzhansky no Brasil em 1943<\/a> by unknown creator via <a href=\"https:\/\/www.flickr.com\/photos\/celycarmo\/\" target=\"_blank\">Cely Carmo<\/a> at Flickr is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\" target=\"_blank\">public domain<\/a>.<\/em><\/figcaption><\/figure>\n<p><em>Genetics and the Origin of Species<\/em>, published in 1937 by Theodosius Dobzhansky (Figure 2.13), was a cornerstone of the modern synthesis, applying genetics to the study of natural selection in wild populations, appealing to both geneticists and field biologists. Dobzhansky was interested in <strong>speciation<\/strong>, particularly in finding out what kept one species distinct from another and how speciation occurred. His research involved fruit flies, the species <em>Drosophila pseudoobscura<\/em>. At the time he began in the 1920s, biologists assumed all members of the same species had nearly identical genes. Dobzhansky traveled from Canada to Mexico capturing wild members of <em>D.<\/em><em>pseudoobscura<\/em>, discovering that different populations had different combinations of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_738\">alleles<\/a><\/strong> (forms of a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1458\">gene<\/a><\/strong>) that distinguished them from other populations, even though they were all members of the same species. What, then, led to the creation of new species? Dobzhansky realized it was sexual selection. Members of the same species are more likely to live among their own kind and to recognize, and prefer, them as mates. Over time, as a result of random mutations, natural selection in a given environment, and <strong>genetic drift<\/strong>, meaning random changes in allele frequencies, members of the same population accumulate mutations distinct to their own <strong>gene pool<\/strong>, eventually becoming genetically distinct from other populations. What this means is that they have become a new <strong>species.<\/strong><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.527999877929688pt;margin-right: 2.886962890625pt;text-indent: 0pt\">From these studies, Dobzhansky and others developed the Bateson-Dobzhansky-Muller model, also known as Dobzhansky-Muller model (Figure 2.14). It is a model of the evolution of genetic incompatibility. Combining genetics with natural selection, the model is important in understanding the role of reproductive isolation during speciation and the role of natural selection in bringing it about. Due to sexual selection (mate preference), populations can become reproductively isolated from one another. Eventually, novel mutations may arise and be selected for in one or both populations, rendering members of each genetically incompatible with the other, resulting in two distinct species.<\/p>\n<figure style=\"width: 601px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image4-4.jpg\" alt=\"Dobzhansky-Muller Model producing hybrids with incompatible mutations. See caption for image details.\" width=\"601\" height=\"348\" \/><figcaption class=\"wp-caption-text\">Figure 2.14: The Dobzhansky-Muller Model: In the ancestral population the genotype is AABB. When two populations become isolated from each other, new mutations can arise. In one population uppercase A evolves into lowercase a, and in the other uppercase B evolves into lowercase b. When the two populations hybridize, it is the first time a and b interact with each other. When these alleles are incompatible, they represent Dobzhansky-Muller incompatibilities. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Bateson-Dobzhansky-Muller_model._.jpg\" target=\"_blank\">Bateson-Dobzhansky-Muller model<\/a> by OrientationEB is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\" target=\"_blank\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<div class=\"textbox\">\n<h2 class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\">Special Topic: Evolution and Natural Selection Observable Today<\/h2>\n<figure style=\"width: 339px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image19-3.jpg\" alt=\"Side view of a brown speckled lizard laying on a plastic lawn chair.\" width=\"339\" height=\"226\" \/><figcaption class=\"wp-caption-text\">Figure 2.15: Puerto Rican Crested Anole photographed in Picard, Dominica. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Anolis_cristatellus_in_Picard,_Dominica-2012_02_15_0339.jpg\" target=\"_blank\">Anolis cristatellus in Picard, Dominica-2012 02 15 0339<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Postdlf\" target=\"_blank\">Postdif<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/deed.en\" target=\"_blank\">CC BY-SA 3.0 Unported License<\/a>.<\/figcaption><\/figure>\n<p>Although this chapter primarily focuses on the past, it is important to remember that natural selection and evolution are still ongoing processes. Climate change, deforestation, urbanization, and other human impacts on the planet are influencing evolution among many contemporary species of plants and animals. One such example occurs among crested anoles (<em>Anolis cristatellus<\/em>), small lizards of the Caribbean jungle that are increasingly making their home in cities (Figure 2.15).<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\">As urban sprawl continues across the planet, shrinking the availability of wilderness habitat, many wild species have come to make their homes in cities. \u201cUrbanization has dramatically transformed landscapes around the world\u2014changing how animals interact with nature, creating \"heat islands\" with higher temperatures, and hurting local biodiversity. Yet many organisms survive and even thrive in these urban environments, taking advantage of new habitats created by humans (National Science Foundation 2023). A recent example of lizards in Puerto Rico demonstrates evolution happening quickly in both behaviour and genes that has come about as a result of the pressures of urban life (Winchell Et al. 2023). Crested anoles, who once lived only in forests, now scurry around towns and cities throughout the Caribbean. As a result of having to sprint across large open spaces, like hot streets and parking lots, they have developed longer limbs. City-living lizards also now sport longer toe pads with special scales that allow them to cling to smooth surfaces, like windows and walls (as well as the plastic patio furniture pictured in Figure 2.15), rather than to the rough surfaces of bark and rock that their forest-living relatives climb. These adaptations enhance their ability to escape predators and survive in cities.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\">Researchers were curious to see if these changes were the result of genetic changes in urban populations, so they captured 96 male lizards in three Puerto Rican regions and compared their genomes to each other and to forest specimens in each location. They found that members of the three city-living populations were genetically distinct from each other, as well as from forest populations in their respective regions. In total, 33 genes in the urban lizards\u2019 genomes were different from their forest-living counterparts and were linked to urbanization. These changes are estimated to have occurred just within the last 30 to 80 generations, suggesting that selective pressures related to survival in urban environments is strong. As study coauthor Kristen Winchell put it, \u201cWe are watching evolution as it is unfolding\u201d (National Public Radio 2023). (If you are interested in hearing more about the study, see \u201c<a href=\"https:\/\/www.pnas.org\/post\/podcast\/lizards-adapt-urban-living\" target=\"_blank\">How Lizards Adapt to Urban Living<\/a>,\u201d an episode of Science Sessions, a free podcast from the Proceedings of the National Academy of Sciences (PNAS 2023) featuring Dr. Winchell and her work.)<\/p>\n<\/div>\n<h2 class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\">Misconceptions About Evolution Through Natural Selection<\/h2>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.836006164550781pt;margin-right: 3.1103515625pt;text-indent: 0pt\">After many years of teaching about evolution and natural selection, it continues to surprise me how many misconceptions exist about how the process works. If you do a web image search for \u201chuman evolution,\u201d the following image is likely to appear (Figure 2.16).<\/p>\n<figure style=\"width: 605px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image2-6.png\" alt=\"Six increasingly upright figures walk in one direction.\" width=\"605\" height=\"222\" \/><figcaption class=\"wp-caption-text\">Figure 2.16: An artist\u2019s visual representation of the process of human evolution. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Human_evolution_scheme.svg\" target=\"_blank\">Human evolution scheme<\/a> by M. Garde is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 3.0211181640625pt;text-indent: 0pt\">What is wrong with this picture? First, it implies that humans evolved from chimpanzees, which is incorrect. Although, as primates, we share a common ancestor very far back in time, we split from other primates, including our closest relatives, the nonhuman apes, several million years ago. This image also suggests that evolution is gradual and progressive; that it is intentional and directional; and that there is an end to it\u2014a stopping point. As you will be learning, evolution takes place in fits and starts, depending on the physical environment, changes in climate, food supply, predation, reproductive success, and other factors. It is also not intentional, in the sense that there is no predetermined end; in fact, if environmental conditions change, species can evolve in different directions or even go extinct. Evolution also does not necessarily progress in the same direction over time. One example is the eel-like creature <em>Qikiqtania wakei<\/em> that lived 375 million years ago. It was originally a fish that evolved to walk on land, then evolved to live back in the water. Early tetrapods like <em>Qikiqtania<\/em> were likely spending more and more time out of the water during this period. The arrangement of bones and joints in their fins was starting to resemble arms and legs, which would have allowed them to prop themselves up in shallow water and survive on mudflats. <em>Qikiqtania\u2019<\/em>s skeletal morphology, however, suggests that it then evolved from having rudimentary fingers and toes back to fins that allowed them to again swim in open water (Stewart Et al. 2022).<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.869003295898438pt;margin-right: 11.6299438476562pt;text-indent: 0pt\">There is also the misperception that natural selection can create entirely new anatomical structures out of thin air in response to changes in environmental pressures. For example, when asked if they can think of ways in which modern humans are continuing to evolve biologically, students often postulate that, as a result of climate change, humans might rapidly develop gills, webbed hands and feet, and learn to breathe underwater in response to rising sea levels. Unfortunately, natural selection can only act on slight variations in anatomy that are already present, and we have no rudimentary physiological system for breathing underwater. Given that natural selection can only act upon existing variation, humans have evolved in such a way that many parts of our bodies are prone to injury. Our knees are one example. The anterior cruciate ligament (ACL) in our knees is \u201cvulnerable to tearing in humans because our upright bipedal posture forces it to endure much more strain than it is designed to\u201d (Lents 2018, 23). When our ancestors made the transition from quadrupedalism to upright walking, we shifted from four bent legs to two straight legs, relying more on our bones than our muscles to support our weight. This is functional for normal walking and running in a straight line, but sudden shifts in direction and momentum, combined with the sizes and weights of modern humans, result in tears in an ACL that is simply not strong enough to bear the stress. If evolution had the capability to engineer a knee from scratch, it would look quite different, and any ligaments involved would likely be larger, stronger, and more flexible. For an interesting look at what anatomically modern humans might look like if we had evolved to withstand the stresses our bodies undergo in our present environment, see \u201c<a href=\"https:\/\/www.radiotimes.com\/tv\/documentaries\/this-is-what-the-perfect-body-looks-like-according-to-science\/\" target=\"_blank\">This is what the perfect body looks like - according to science<\/a>,\u201d which was proposed by biological anthropologist Alice Roberts (Harrison 2018).<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.836006164550781pt;margin-right: 9.61920166015625pt;text-indent: 0pt\">Another misperception about evolution is that some species are \u201cmore evolved\u201d than others. Every species currently alive on the planet today is the result of millennia of natural selection that has rendered current members of that species well-adapted to their respective environments. Humans are no more \u201cevolved\u201d than fruit flies or yeast. What sets us apart are our cultural and technological abilities, which have allowed us to successfully survive in a wide variety of physical environments, many of which are now becoming too hot, too wet, or too dry to sustain human life without a great deal of technological intervention (IPCC 2022).<\/p>\n<figure style=\"width: 366px\" class=\"wp-caption alignright\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image5-3.jpg\" alt=\"A male dragonfly with a light blue body, transparent wings, and black markings rests on a twig.\" width=\"366\" height=\"282\" \/><figcaption class=\"wp-caption-text\">Figure 2.17: Adult male Common Whitetail Dragonfly, <a href=\"https:\/\/commons.wikimedia.org\/wiki\/Libellula_lydia\" target=\"_blank\">Libellula lydia<\/a>. Credit: <a href=\"https:\/\/www.cirrusimage.com\/dragonfly_common_whitetail.htm\" target=\"_blank\">Common Whitetail Dragonfly \u2013 Plathemis lydia<\/a> by Bruce Marlin is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.5\" target=\"_blank\">CC BY-SA 2.5 License<\/a>.<\/figcaption><\/figure>\n<p>There is also some confusion about what \u201cfitness\u201d actually means and a failure to grasp that it changes as environmental conditions change. Evolutionary \u201cfitness\u201d is different from physical fitness. \u201cFitness\u201d in evolutionary terms refers to an individual\u2019s ability to survive and reproduce viable offspring who also survive and reproduce. Evolutionary fitness and reproductive success are highly dependent on specific environmental conditions, which can shift over time, greatly affecting the relative fitness of individuals in a population. Recent research on the impacts of climate change on dragonflies will serve to illustrate the point (Figure 2.17).<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.748001098632812pt;margin-right: 3.8743896484375pt;text-indent: 0.594001770019531pt\">Pictured here is a male dragonfly, who, you will notice, has distinctive black markings on its wings. This is due to melanization. Males control breeding, and those with more ornamentation tend to attract more mates and to successfully ward off male competitors. Higher levels of melanization, however, have negative consequences for males in warming climates. The black markings absorb heat, elevating body temperatures, which can cause overheating, reduce male fighting ability, and even lead to death (Moore Et al. 2021). Females are not as adversely affected because they spend more time in shaded areas, while males are more often flying in sunlit areas, fending off rivals. However, as highly melanized males become less viable, wing colouration is undergoing selection in males. In other words, what constitutes being \u201cfit\u201d for males has changed, favouring those who have fewer of the black markings and, therefore, are less negatively impacted by warming temperatures. Note that natural selection acts on individuals, \u201cselecting\u201d those who happen to be fit for particular environmental conditions at a particular point in time. Evolution, though, happens at the level of the population. If the climate continues to warm, populations of dragonflies who inhabit warming areas will increasingly exhibit less ornamentation in males.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.858001708984375pt;margin-right: 5.50946044921875pt;text-indent: 0pt\">Lastly, natural selection can only act on characteristics that influence reproductive success. Deleterious traits that have nothing to do with one\u2019s ability to reproduce and successfully rear offspring to reproductive age will continue to be passed on. For example, the author of this chapter is a natural redhead, and redheads are predisposed genetically to a number of conditions that can negatively affect health (Colliss Harvey 2015), but some of these conditions are not diagnosed until later in life. One example is Parkinson\u2019s disease (Chen Et al. 2017), which is a degenerative neurological disorder. The average age of diagnosis of Parkinson\u2019s is 60 years of age, meaning redheads may encounter such a diagnosis well past childbearing age, having already passed on the genetic predisposition. Thus, Parkinson\u2019s disease cannot be selected out from the redhead family tree.<\/p>\n<\/div>\n<h2 class=\"__UNKNOWN__\">Are We Still Evolving?<\/h2>\n<div class=\"__UNKNOWN__\">\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">After reading this chapter, many students are curious to know if humans are still evolving. The answer is yes. As a species, we continue to respond to selective pressures biologically and culturally. This final section will focus on three contemporary examples of human evolution. Before beginning, let\u2019s review the conditions necessary for natural selection to operate on a trait. First, the trait must be heritable, meaning it is transmitted genetically from generation to generation. There must also be variation of the trait within the population and the trait must influence reproductive success. Three examples of traits that meet these criteria are immunity to the Human Immunodeficiency Virus (HIV), height, and wisdom teeth (Andrews, Kalinowski, &amp; Leonard 2011).<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">AIDS is a potentially fatal infectious disease caused by HIV, a zoonosis believed to be derived from Simian Immunodeficiency Viruses (SIVs) found in chimpanzees and monkeys and most likely transmitted to humans through the butchering of infected animals (Sharp &amp; Hahn 2011). In total, 40 million people have died from AIDS-related illnesses since the start of the global epidemic in the 1980s. There were 38.4 million people around the world living with AIDS as of 2021, including 1.5 million new cases and 650,000 deaths in that year alone (UNAIDS 2021). A disease causing this level of morbidity and mortality represents a major selective pressure, especially given that infection can occur before birth (Goulder Et al. 2016), thereby affecting future reproductive success.<\/p>\n<figure style=\"width: 323px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image17-7.png\" alt=\"A political map of Europe and North Africa associated with percentages ranging from 0% to 16.4%.\" width=\"323\" height=\"391\" \/><figcaption class=\"wp-caption-text\">Figure 2.19: Map of CCR5-delta32 allele distribution. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-11\/\" target=\"_blank\">Map of CCR5-delta32 allele distribution (Figure 16.10)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Katie Nelson is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available.<\/a> [Includes <a href=\"https:\/\/pixabay.com\/vectors\/europe-map-western-political-32847\/\" target=\"_blank\">Europe Map Western Political 32847<\/a> by <a href=\"https:\/\/pixabay.com\/users\/clker-free-vector-images-3736\/\" target=\"_blank\">Clker-Free-Vector-Images<\/a>, <a href=\"https:\/\/pixabay.com\/service\/terms\/#license\" target=\"_blank\">Pixabay License<\/a>; data from Solloch et al. 2017.]<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The majority of people in the world are highly susceptible to HIV infection, but some are not. These latter individuals are homozygous for a rare, recessive allele at the CCR5 locus that makes them immune to HIV. Heterozygotes who inherit a single copy of this allele are more resistant to infection and, when infected, the disease takes longer to progress in the event that they are infected. The mechanism by which the allele prevents infection involves a 32-base pair deletion in the DNA sequence of the CCR5 gene, creating a nonfunctioning receptor on the surface of the cell that prevents HIV from infecting the cell. The allele is inherited as a simple Mendelian trait, and there is variation in its prevalence, ranging as high as 14% of the population in northern Europe and Russia (Novembre, Galvani, and Slatkin 2005; see Figure 2.19). What is interesting about the allele\u2019s geographic distribution is that it does not map onto parts of the world with the highest rates of HIV infection (Figure 2.20), suggesting that AIDS was not the original selective pressure favouring this allele.<\/p>\n<figure style=\"width: 498px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image7-8.png\" alt=\"World map with different HIV infection rates throughout the world.\" width=\"498\" height=\"253\" \/><figcaption class=\"wp-caption-text\">Figure 2.20: World map of countries shaded according to their HIV\/AIDS adult prevalence rate in 2020. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available.<\/a> Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:World_map_of_countries_by_HIV-AIDS_adult_prevalence_rate_%282020%29.svg\" target=\"_blank\">World map of countries by HIV-AIDS adult prevalence rate (2020)<\/a> by LuccaSSC has been designated to the <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/cc0\/\" target=\"_blank\">public domain (CC0 1.0)<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Given its current geographic distribution, the bubonic plague, which ravaged Europe repeatedly from the 14th to the 19th centuries (Pamuk 2007), was initially proposed as the selective agent. Subsequent research suggests smallpox, which killed up to 400,000 people annually in 18th-century Europe (Hays 2005), was more likely the selective pressure (Novembre, Galvani, &amp; Slatkin 2005). Given the mortality rates for smallpox (Crosby 2003), an allele that conferred immunity was highly advantageous, as it is for those faced with the threat of HIV infection today.<\/p>\n<p class=\"import-Normal\">Height is another example of a trait experiencing selective pressure. If you have ever toured a historical site, you have likely hit your head on a doorframe or become claustrophobic trying to squeeze down a narrow hallway under a lower-than-average ceiling. It is not your imagination. Humans have gotten taller in recent centuries. In fact, the average height of people in industrialized nations has increased approximately 10 centimetres in the past 150 years. This increase has been attributed to improvements in nutrition, sanitation, and access to medical care (Hatton 2014). But this is only part of the story.<\/p>\n<p class=\"import-Normal\">Height is highly heritable. Studies indicate 80% of variation in height within populations is due to genetics, with 697 different genetic variances identified as having an effect on adult stature (Devuyst 2014). Multiple studies also demonstrate a positive relationship between height and reproductive success for men (Andrews, Kalinowsky, &amp; Leonard 2011). This is primarily due to sexual selection and nonrandom mating, namely women\u2019s preferences for taller men, which may explain why height is one characteristic men often lie about on dating websites (Guadagno, Okdie, &amp; Kruse 2012). Sexual selection also plays out with regard to economic success in Western cultures, with taller men more likely to be in higher-level positions that pay well. Research demonstrates an inch of height is worth an additional $789 per year in salary, meaning a man who is six feet tall will earn on average $5,525 more per year than an identical man who is five foot five purely due to heightism bias (Gladwell 2007). Over the course of a career, this can add up to hundreds of thousands of dollars, likely allowing taller men to attract more potential mates, increasing their reproductive success.<\/p>\n<p class=\"import-Normal\">Wisdom teeth are also undergoing evolutionary pressure. Have you or anyone in your family had their wisdom teeth removed? While it can be a painful and expensive process, it is a common experience in Western nations. It begs the question as to why there is no longer room in our mouths for all of our teeth? Biological anthropologist Daniel Lieberman offers several reasons, including that modern humans are growing faster and maturing earlier, which could be leading to impaction if skeletal growth takes place faster than dental growth. He also argues that the soft diets many modern humans consume generate insufficient strain to stimulate enough growth in our jaws to accommodate all of our teeth. Lastly, as the human brain has expanded over the past hundreds of thousands of years, it is taking up more space in the skull, causing the jaw to shrink, leaving no room for third molars (Lieberman 2011).<\/p>\n<p class=\"import-Normal\">Conversely, do you know anyone whose wisdom teeth never came in? That is fairly common in some populations, suggesting evolutionary pressure favouring the absence of wisdom teeth has been culturally influenced. The oldest fossil evidence of skulls missing third molars was found in China and is 300,000 to 400,000 years old, suggesting the earliest mutation selecting against the eruption of wisdom teeth arose in Asia (Main 2013). Since that time, jaws have continued to decrease in size to the point they often cannot accommodate third molars, which can become impacted, painful, and even infected, a condition physical anthropologist Alan Main argues might have interfered with the ability to survive and reproduce in ancestral populations (Main 2013). As we have learned, a mutation that positively influences reproductive success\u2014such as being born without the trait to develop wisdom teeth\u2014would likely be selected for over time. Evidence in modern humans suggests that this is the case, with 40% of modern Asians and 45% of Native Alaskans and Greenlanders (populations descended from Asian populations) lacking wisdom teeth. The percentage among those of European descent ranges from 10 to 25% and for African Americans is 11% (Main 2013). Later chapters of this textbook emphasize that directional selection progresses along a particular path until the environment changes and a trait is no longer advantageous. In the case of wisdom teeth, the ability of modern dentistry to preempt impaction through surgery may, in fact, be what is preventing natural selection from doing away with wisdom teeth altogether.<\/p>\n<h2>Cultural Connections and Contemporary Implications<\/h2>\n<p>By the end of the Renaissance, knowledge inherited from Greek and Islamic scholars profoundly influenced how humans perceived nature and the scientific method itself. This period marked a major epistemic shift where the way of understanding and studying the natural world was evolving. Historical and religious worldviews were closely intertwined during this time: ancient ideas were often incorporated into theological frameworks, as exemplified by Archbishop James Ussher\u2019s famous calculation that the world was created on October 23, 4004 BC.<\/p>\n<p>The Enlightenment of the 17th and 18th centuries introduced rapid technological development and new philosophies of science. However, it also brought challenges. While curiosity about nature expanded, many thinkers continued to treat knowledge as fixed and immutable, anchored by biblical interpretation, which was often deemed too sacred to question.<\/p>\n<p>The second major scientific revolution emerged during the Industrial Era, influenced by European thinkers such as Charles Darwin, John Ray, Robert Hooke, James Hutton, and Jean-Baptiste Lamarck. This era saw groundbreaking advances in geology, paleontology, and biology. Concepts such as catastrophism, uniformitarianism, inheritance, and acquired characteristics reshaped humanity's understanding of the earth\u2019s history and the continuity of life.<\/p>\n<p>Yet, scientific ideas never exist in isolation as they are deeply interwoven with social and cultural life. As these thinkers sought to explain nature, evolution, and, by extension, human existence, their ideas inevitably intersected with religious worldviews. This long-standing entanglement and occasional tension between science and religion continue to shape how societies understand the origins of life today. For example, a 2023 Gallup Poll measuring <a href=\"https:\/\/news.gallup.com\/poll\/647594\/majority-credits-god-humankind-not-creationism.aspx\" target=\"_blank\">Americans\u2019 beliefs about human origins<\/a> revealed that 37% believed God created humans in their present form, 34% argued that humans developed through evolution with God\u2019s guidance, and only 24% of U.S. adults accepted the scientific theory of evolution. A similar reality exists in Canada, where <a href=\"https:\/\/researchco.ca\/2023\/04\/14\/evolution-2023\/#:~:text=By%20a%203%2Dto%2D1,within%20the%20last%2010%2C000%20years.\" target=\"_blank\">1 in 5 Canadians<\/a> believe God created human beings in their present form within the last 10,000 years.<\/p>\n<p>Consequently, these perspectives reflect two distinct ways of reconstructing the past. Science pursues truth through observation, testing, and empirical evidence, while religion offers meaning through faith, belief, and spiritual interpretation. As a result, attempts to understand the origins of humanity often follow divergent paths. But what happens when desire or ideology, rather than evidence, drives our reconstructions of the past of both nature and ourselves?<\/p>\n<h4>Discussion Questions<\/h4>\n<ul>\n<li style=\"font-weight: 400\">Can religion and science work collaboratively to deepen our understanding of life and the universe?<\/li>\n<li style=\"font-weight: 400\">What social tensions arise between human culture and scientific advancement?Can you provide some examples?<\/li>\n<li style=\"font-weight: 400\">How is modern society influencing our understanding of evolution happening today?<\/li>\n<li style=\"font-weight: 400\">Beyond religion, what other socio-cultural factors influence scientific understanding? Can you provide some examples?<\/li>\n<li style=\"font-weight: 400\">What does it mean when a culture limits the next generation\u2019s understanding to its own worldview? Is it possible for us to think or move beyond our cultural boundaries?<\/li>\n<\/ul>\n<h2 class=\"import-Normal\" style=\"margin-left: 1.364006042480469pt;text-indent: 0pt\">Key Developments in Evolutionary Thought<\/h2>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 482.25pt\">\n<tbody>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">4th century BCE<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Aristotle<\/p>\n<p class=\"import-Normal\">(384\u2013322 BCE)<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">\u201cFounder of Biology.\u201d Publishes <em>History of Animals<\/em>, a biological classification system of over 500 animals based on structure, physiology, reproduction, and behaviour. Also creates the \u201cGreat Chain of Being,\u201d ranking species and placing humans closest to God.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">8th\u20139th century CE<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Al-Jahiz<\/p>\n<p class=\"import-Normal\">(776\u2013868 CE)<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Writes seven-volume <em>Book of Animals<\/em>, which includes animal classifications and food chains. Introduces concept of biological evolution and its mechanisms.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1011\u20131021<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Ibn al-Haythem<\/p>\n<p class=\"import-Normal\">(965\u20131040 CE)<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">\u201cFather of Modern Optics.\u201d Uses experimental science to catalogue how vision works and discovers laws of reflection and refraction. Publishes <em>Book of Optics<\/em> and invents <em>camera obscura<\/em>, the foundation for modern photography.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1620<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Francis Bacon<\/p>\n<p class=\"import-Normal\">(1561\u20131626)<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">\u201cFather of Empiricism.\u201d Publishes <em>The Novum Annum<\/em>, formulating the scientific method based on observation and inductive reasoning.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1686<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">John Ray<\/p>\n<p class=\"import-Normal\">(1627\u20131705)<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">First to publish a biological definition of <em>species<\/em> in <em>History of Plants<\/em>.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1749<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Comte de Buffon<\/p>\n<p class=\"import-Normal\">(1707\u20131788)<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Publishes <em>Histoire Naturelle<\/em>, comparing anatomical structures across species using methods still in use today. Inspires Lamarck and Cuvier.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1758<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Carl von Linne<\/p>\n<p class=\"import-Normal\">(Carolus Linnaeus)<\/p>\n<p class=\"import-Normal\">(1707\u20131778)<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Introduces system of binomial nomenclature. Publishes <em>Systema Naturae<\/em>, the tenth edition of which introduces the designation <em>Homo sapiens <\/em>for humans.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1788<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">James Hutton<\/p>\n<p class=\"import-Normal\">(1726\u20131797)<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">\u201cFather of Geology.\u201d Publishes <em>Theory of the Earth<\/em>; introduces idea of Deep Time; explains how features of the earth were formed through the actions of rain, wind, rivers, and volcanic eruptions.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1798<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Thomas Malthus<\/p>\n<p class=\"import-Normal\">(1766\u20131834)<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Economist and \u201cFather of Statistics.\u201d Publishes <em>An Essay on Population<\/em>; introduces concept of carrying capacity; explains how populations outstrip the food supply, leaving some individuals to die off; inspires Darwin\u2019s idea of \u201cnatural selection.\u201d<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1809<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Jean-Baptiste Lamarck<\/p>\n<p class=\"import-Normal\">(1744\u20131829)<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Publishes theory of the Inheritance of acquired characteristics; is the first Western scientist to propose a mechanism explaining how traits change in species over time and to recognize the importance of the physical environment in acting on species and their survival.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1810<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Georges Cuvier<\/p>\n<p class=\"import-Normal\">(1769\u20131832)<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Paleontologist\/comparative anatomist; proved species went extinct; proposed the Theory of Catastrophism.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1830<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Charles Lyell<\/p>\n<p class=\"import-Normal\">(1797\u20131875)<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Establishes geology as a science. Publishes first edition of <em>The Principles of Geology <\/em>(1830\u201333); issuing 12 total editions in his lifetime, each updated according to new scientific data.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1858<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Alfred Russel Wallace<\/p>\n<p class=\"import-Normal\">(1823\u20131913)<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Sends scientific paper to Darwin titled \u201cOn the Tendency of Varieties to Depart Indefinitely from the Original Type,\u201d essentially espousing the concept of natural selection; a reading of the papers by both Wallace and Darwin to the Linnaean Society is conducted by Lyell.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1859<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Charles Darwin<\/p>\n<p class=\"import-Normal\">(1809\u20131882)<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Publishes <em>On the Origin of Species by Means of Natural Selection<\/em> (1859).<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1865<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Gregor Mendel<\/p>\n<p class=\"import-Normal\">(1822\u20131884)<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Publishes <em>Experiments in Plant Hybridization<\/em> (1865), outlining the fundamentals of genetic inheritance.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1889<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">August Weismann<\/p>\n<p class=\"import-Normal\">(1834\u20131914)<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Publishes <em>Essays Upon Heredity <\/em>(1889), disproving the inheritance of acquired characteristics. Publishes <em>The Germ Plasm <\/em>(1892), postulating an early idea of inheritance through sexual reproduction.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1937<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Theodosius Dobzhansky<\/p>\n<p class=\"import-Normal\">(1900\u20131975)<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">One of the founders of the Modern Synthesis of biology and genetics. Publishes <em>Genetics and the Origin of Species<\/em> (1937). Documents a genetic model of speciation through reproductive isolation.<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div class=\"textbox shaded\">\n<h2>Summary<\/h2>\n<p>Firstly, it is important to recognize that the global discourse on evolutionary thought emerged from a Western European colonial legacy; often centring eurocentric perspectives while overlooking other intellectual traditions. This legacy has resulted in a lasting influence in how the knowledge was\u2013and continues to be\u2013structured and understood.<\/p>\n<p>From its earliest ideas to today\u2019s genomic research, evolutionary thought has demonstrated that species, including our own, are not static, but are part of ongoing processes shaped by variation, natural selection, and shifting conditions. A persistent misconception is that evolution implies progress toward more advanced or \u2018better\u2019 forms; in reality, it reflects context-specific adaptations that enhance survival and reproduction. Humans exemplify this ongoing process, adapting through traits such as resistance to disease, tolerance of new foods, and responses to rapidly changing modern environments.<\/p>\n<h2 class=\"import-Normal\">Review Questions<\/h2>\n<ul>\n<li class=\"import-Normal\">Summarize the major scientific developments that led to the formulation of the theory of natural selection.<\/li>\n<li class=\"import-Normal\">Explain how natural selection operates and how it leads to evolution in populations.<\/li>\n<li class=\"import-Normal\">Explain the importance of genetics to an understanding of human evolution.<\/li>\n<li class=\"import-Normal\">Have you observed current examples of evolution taking place where you live? In which species? Which forces of evolution are involved?<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<h2 class=\"__UNKNOWN__\">Key Terms<\/h2>\n<div class=\"__UNKNOWN__\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.902000427246094pt;margin-right: 18.1800537109375pt;text-indent: 0.406997680664062pt\"><strong>Allele<\/strong>: A nonidentical DNA sequence found in the same gene location on a homologous chromosome, or gene copy, that codes for the same trait but produces a different phenotype.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.836006164550781pt;margin-right: 4.92626953125pt;text-indent: 0.34100341796875pt\"><strong>Artificial selection<\/strong>: The identification by humans of desirable traits in plants and animals, and the subsequent steps taken to enhance and perpetuate those traits in future generations.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.836006164550781pt;margin-right: 0.62152099609375pt;text-indent: 0.461997985839844pt\"><strong>Binomial nomenclature<\/strong>: A system of classification in which a species of animal or plant receives a name consisting of two terms: the first identifies the genus to which it belongs, and the second identifies the species.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 6.76727294921875pt;text-indent: 0pt\"><strong>Carrying capacity<\/strong>: The number of living organisms, including animals, crops, and humans, that a geographic area can support without environmental degradation.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.924003601074219pt;margin-right: 3.10675048828125pt;text-indent: 0.0879974365234375pt\"><strong>Catastrophism<\/strong>: The theory that the Earth\u2019s geology has largely been shaped by sudden, short-lived, violent events, possibly worldwide in scope. Compare to uniformitarianism.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.924003601074219pt;margin-right: 3.10675048828125pt;text-indent: 0.0879974365234375pt\"><strong>Comparative anatomy<\/strong>: Georges-Louis Leclerc\u2019s technique of comparing similar anatomical structures across different species.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.924003601074219pt;margin-right: 3.10675048828125pt;text-indent: 0.0879974365234375pt\"><strong>Creationism<\/strong>: The belief that the universe and all living organisms originate from specific acts of divine creation, as in the Biblical account, rather than by natural processes such as evolution.<\/p>\n<p class=\"import-Normal\" style=\"margin-right: 0.0257568359375pt\"><strong>Empiricism<\/strong>: The idea that all learning and knowledge derives from experience and observation. It became prominent in the 17th and 18th centuries in western Europe due to the rise of experimental science.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.858001708984375pt;margin-right: 53.6096496582031pt;text-indent: 0.44000244140625pt\"><strong>Evolution<\/strong>: In a biological sense, this term refers to cumulative inherited change in a population of organisms through time. More specifically, <em>evolution<\/em> is defined as a change in allele (gene) frequencies from one generation to the next among members of an interbreeding population.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 1.298004150390625pt;margin-right: 0pt;text-indent: 0pt\"><strong>Extant<\/strong>: Still in existence; surviving.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 1.199005126953125pt;margin-right: 19.8264770507812pt;text-indent: 0.0989990234375pt\"><strong>Extinct<\/strong>: Said of a species, family, or other group of animals or plants that has no living members; no longer in existence.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 1.199005126953125pt;margin-right: 19.8264770507812pt;text-indent: 0.0989990234375pt\"><strong>Fixity of <\/strong><strong>Species<\/strong>: The idea that a species, once created, remains unchanged over time.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.836006164550781pt;margin-right: 6.576171875pt;text-indent: 0pt\"><strong>Gene<\/strong>: A sequence of DNA that provides coding information for the construction of proteins.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0.836006164550781pt;margin-right: 6.576171875pt;text-indent: 0pt\"><strong>Genetic drift<\/strong>: Random changes in allele frequencies within a population from one generation to the next.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.836006164550781pt;margin-right: 6.576171875pt;text-indent: 0pt\"><strong>Gene flow<\/strong>: The introduction of new genetic material into a population through interbreeding between two distinct populations.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0.836006164550781pt;margin-right: 6.576171875pt;text-indent: 0pt\"><strong>Gene pool<\/strong>: The entire collection of genetic material in a breeding community that can be passed from one generation to the next.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0.836006164550781pt;margin-right: 6.576171875pt;text-indent: 0pt\"><strong>Genotype<\/strong>: The genotype of an organism is its complete set of genetic material\u2014its unique sequence of DNA. Genotype also refers to the alleles or variants an individual carries in a particular gene or genetic location.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.693000793457031pt;margin-right: 1.15521240234375pt;text-indent: 0.605003356933594pt\"><strong>Hybrid<\/strong>: Offspring of parents that differ in genetically determined traits.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.924003601074219pt;margin-right: 16.4979858398438pt;text-indent: 0.319000244140625pt\"><strong>Intelligent design<\/strong>: A pseudoscientific set of beliefs based on the notion that life on earth is so complex that it cannot be explained by the scientific theory of evolution and therefore must have been designed by a supernatural entity.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.594001770019531pt;margin-right: 24.672607421875pt;text-indent: 0.681999206542969pt\"><strong>Macroevolution<\/strong>: Large and often-complex changes in biological populations, such as species formation.<\/p>\n<p><strong>Microevolution<\/strong>: Changes in the frequency of a gene or allele in an interbreeding population.<\/p>\n<p><strong>M<\/strong><strong>odern synthesis<\/strong>: The mid\u201320th century merging of Mendelian genetics with Darwinian evolution that resulted in a unified theory of evolution.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.693000793457031pt;margin-right: 3.12261962890625pt;text-indent: 0.583000183105469pt\"><strong>Natural selection<\/strong>: The natural process by which the survival and reproductive success of individuals or groups within an interbreeding population that are best adjusted to their environment leads to the perpetuation of genetic qualities best suited to that particular environment at that point in time.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.693000793457031pt;margin-right: 19.8097534179688pt;text-indent: 0.605003356933594pt\"><strong>Phenotype<\/strong>: The detectable or visible expression of an organism\u2019s <em>genotype<\/em>.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.693000793457031pt;margin-right: 7.392578125pt;text-indent: 0.198005676269531pt\"><strong>Scientific method<\/strong>: A method of procedure that has characterized natural science since the 17th century, consisting of systematic observation, measurement, experimentation, and the formulation, testing, and modification of hypotheses.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0.858001708984375pt;margin-right: 2.66143798828125pt;text-indent: 0.0330047607421875pt\"><strong>Speciation<\/strong>: The process by which new genetically distinct species evolve from the main population, usually through geographic isolation or other barriers to gene flow.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.858001708984375pt;margin-right: 2.66143798828125pt;text-indent: 0.0330047607421875pt\"><strong>Species<\/strong>: A group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding. The species is the principal natural taxonomic unit, ranking below a genus and denoted by a Latin binomial (e.g., <em>Homo sapiens<\/em>).<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0.495002746582031pt;margin-right: 1.47552490234375pt;text-indent: 0pt\"><strong>Uniformitarian<\/strong><strong>ism<\/strong>: The theory that changes in the earth's crust during geologic history have resulted from the action of continuous and uniform processes\u2014such as wind, precipitation, evaporation, condensation, erosion, and volcanic action\u2014that continue to act in the present. Compare to <strong>c<\/strong><em>atastrophism<\/em>.<\/p>\n<h2 class=\"import-Normal\">For Further Exploration<strong><br \/>\n<\/strong><\/h2>\n<p>Costa, James T. 2017. <em>Darwin\u2019s Backyard: How Small Experiments Led to a Big Theory<\/em>. New York: W.W. Norton.<\/p>\n<p>Darwin, Charles. 1905. <em>The Voyage of the Beagle<\/em>. (Originally published in 1839 as <em>Journal and Remarks<\/em>). [Author\u2019s note: Several editions exist with different publishers, including illustrated editions, paperback editions, and e-books.]<\/p>\n<p>Moore, John A. 1993. <em>Science as a Way of Knowing: The Foundations of Modern Biology<\/em>. Cambridge, MA: Harvard University Press.<\/p>\n<h2 class=\"import-Normal\">References<\/h2>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 29.0806274414062pt;text-indent: 0pt\">Al-Haytham, Ibn. 1011-1021. <em>Kit\u0101b al-Man\u0101\u1e93ir<\/em> (Book of Optics). Cairo, Egypt.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 29.0806274414062pt;text-indent: 0pt\">Al-Jahiz. 776\u2013868 CE. <em>Kitab al-Hayawan<\/em> (<em>Book of <\/em><em>Animals<\/em><em>).<\/em><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Andrews, Tessa M., Steven T. Kalinowski, and Mary J. Leonard. 2011. \u201cAre Humans Evolving? A Classroom Discussion to Change Students\u2019 Misconceptions Regarding Natural Selection.\u201d <em>Evolution: Education and Outreach<\/em> 4 (3): 456\u2013466.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Aristotle. 384-322 BCE. <em>History of <\/em><em>Animals<\/em><em>.<\/em><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Asghar, Anila, Salman Hameed, and Najme Kashani Farahani. 2014. \u201cEvolution in Biology Textbooks: A Comparative Analysis of Five Muslim Countries.\u201d Religion &amp; Education 41 (1). Accessed February 12, 2023. https:\/\/www.tandfonline.com\/doi\/abs\/10.1080\/15507394.2014.855081.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Associated Press. January 10, 2023. \u201cForest Lizards Have Genetically Morphed To Survive Life In The City, Researchers Say.\u201d <em>National Public Radio (NPR)<\/em>. Retrieved February 19, 2023 from https:\/\/www.npr.org\/2023\/01\/10\/1148150056\/forest-lizards-genetically-morphed-cities.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 14.25pt;text-indent: 0pt\">Burkhardt, Richard W. 2013. \u201cLamarck, Evolution, and the Inheritance of Acquired Characters.\u201d <em>Genetics<\/em> 194 (4): 793\u2013805.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 21.4119873046875pt;text-indent: 0pt\">Chen, Xiqun, Danielle Feng, Michael A. Schwartzchild, and Xiang Gao. 2017. \u201cRed Hair, MC1R Variants, and Risk for Parkinson\u2019s Disease\u2014A Meta-Analysis.\u201d <em>Annals of Clinical and Translational Neurology<\/em> 4 (3): 212\u2013216.https:\/\/doi.org\/10.1002\/acn3.381.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 4.13275146484375pt;text-indent: 0pt\">Colliss Harvey, Jacky. 2015. <em>Red: A History of the Redhead<\/em>. 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Westport, CT: Praeger.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 27.93212890625pt;text-indent: 0pt\">Darwin, Charles. 1859. <em>On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life. <\/em>First Edition. London: John Murray.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 35.9136962890625pt;text-indent: 0pt\">Darwin, Francis, ed. 2001[1897]. <em>The Life &amp; Letters of Charles Darwin<\/em>, vol. 2. Honolulu: University Press of the Pacific.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 7.79656982421875pt;text-indent: 0pt\">Desilver, Drew. 2017. \u201cU.S. Students\u2019 Academic Achievement Still Lags That of Their Peers in Many Other Countries.\u201d Pew Research Center, February 15. 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Scotland: Royal Society of Edinburgh.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 2.458251953125pt;text-indent: 0pt\">IPCC. 2022. <em>Climate Change 2022: Impacts, Adaptation, and Vulnerability. <\/em>Contribution of Working Group II to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change, edited by H.-O. P\u00f6rtner, D.C. Roberts, M. Tignor, E.S. Poloczanska, K. Mintenbeck, A. Alegr\u00eda, M. Craig, S. Langsdorf, S. L\u00f6schke, V. M\u00f6ller, A. Okem, and B. Rama. Cambridge: Cambridge University Press. https:\/\/www.ipcc.ch\/report\/ar6\/wg2\/.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 2.458251953125pt;text-indent: 0pt\">Jones, Stephen. 2017. \u201cReligion, Science, and Evolutionary Theory\u201d[an interview with Salman Hameed]. Podcast, <em>The Religious Studies Project<\/em>, January 30. 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Cambridge, MA: Harvard University Press.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 15.0872802734375pt;text-indent: 0pt\">Lindberg, David C. 1992. <em>The Beginnings of Western Science: The European Scientific Tradition in Philosophical, Religious, and Institutional Context, 600 B.C. to A.D. 1450<\/em>. Chicago: The University of Chicago Press.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Linnaeus, Carl. 1736. <em>Systema Naturae<\/em>. First Edition. Stockholm: Laurentius Salvius.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 21.6511840820312pt;text-indent: 0pt\">Love, Shayla. 2020. \u201cA Thousand Years before Darwin, Islamic Scholars Were Writing about Evolution.\u201d VICE World News, October 5. 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Accessed February 18, 2023. https:\/\/embryo.asu.edu\/handle\/10776\/8284.<\/p>\n<\/div>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1695_1844\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1695_1844\"><div tabindex=\"-1\"><div class=\"textbox\">Learn more about <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/about-the-authors\/\">authors and editors<\/a>,<a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/student-contributors\/\"> Hess' student contributions<\/a>, and <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/versioning-history\/\">versioning history<\/a>.<\/div>\n<div class=\"textbox textbox--learning-objectives\">\n<header class=\"textbox__header\">\n<h2 class=\"textbox__title\">Learning Objectives<\/h2>\n<\/header>\n<div class=\"textbox__content\">\n<ul>\n<li>Identify and describe the major developments in scientific thought that led to the discovery of evolutionary processes.<\/li>\n<li>Explain how natural selection works and results in evolutionary change over time.<\/li>\n<li>Explain what is meant by the \u201cModern Synthesis\u201d and its impacts on evolutionary thought.<\/li>\n<li>Discuss the teaching of human evolution in the U.S. and abroad.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<h2 class=\"__UNKNOWN__\">The Beginnings of Evolutionary Thinking<\/h2>\n<div class=\"__UNKNOWN__\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.627006530761719pt;margin-right: 3.917236328125pt;text-indent: 0pt\">Throughout our evolutionary history, humans have developed an understanding of the natural world as they interacted with and extracted resources from it. To survive, our earliest ancestors possessed an understanding of the physical environment, including weather patterns, animal behaviour, edible and medicinal plants, locations of water, and seasonal cycles. Many ancient cultures, including those of the Americas (Dunbar-Ortiz 2014), Mesopotamia, and Egypt, left writings, hieroglyphics, and stories passed down through oral tradition detailing their understanding of the natural environment, human and zoological anatomy, botany, and medical practices (Moore 1993).<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 1.209999084472656pt;margin-right: 11.6515502929688pt;text-indent: 0pt\">There are also over 2,000 years of organized thought and writing regarding <strong>evolution<\/strong>, including contributions from Greek, Roman, and Islamic scholars. Three examples of note are included here. The Greek philosopher Aristotle (384\u2013322 BCE) studied the natural world, publishing several volumes on animals based on systematic observations, rather than attributing what he observed to divine intervention, as his contemporaries were doing (Figure 2.1). Aristotle\u2019s system for the biological classification of nearly 500 species of animals was based on his own observations and dissections, interviews with specialists such as beekeepers and fishermen, and accounts of travelers. His nine book <em>History of Animals<\/em>, published in the 4th century BC (n.d.), was one of the first zoological taxonomies ever created. Aristotle\u2019s primary contribution to the classification of biological species was to recognize that natural groups are based on structure, physiology, mode of reproduction, and behaviour (Moore 1993, 39).<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 1.243003845214844pt;margin-right: 31.8323364257812pt;text-indent: 0pt\"><img class=\"aligncenter\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2023\/03\/image3-5.jpg\" alt=\"Large orange octopus on ocean floor.\" width=\"240\" height=\"321\" \/><\/p>\n<figure style=\"width: 338px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image12-4.jpg\" alt=\"Elephant half-submerged in a body of water with a ferry of human watchers behind.\" width=\"338\" height=\"231\" \/><figcaption class=\"wp-caption-text\">Figure 2.1a-b: Aristotle was the first to publish that a. octopuses can change their colours when disturbed and b. elephants use their trunks as a snorkel when crossing deep water. Credit: a. <a href=\"https:\/\/en.wikipedia.org\/wiki\/File:Octopus_macropus.jpg\" target=\"_blank\">Octopus macropus<\/a> by <a href=\"https:\/\/subnormali-team.blogspot.com\/2006_12_01_archive.html\">SUBnormali Team<\/a> (originally from <a href=\"https:\/\/it.wikipedia.org\/wiki\/Utente:Yoruno\" target=\"_blank\">Yoruno<\/a>) is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/#:~:text=You%20are%20free%20to%3A,for%20any%20purpose%2C%20even%20commercially.\" target=\"_blank\">CC-BY-SA 3.0 License<\/a>. b. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Elephant_swimming,_Botswana_(cropped).jpg\">Elephant swimming, Botswana (cropped)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/8721758@N06\" target=\"_blank\">Jorge L\u00e1scar<\/a> from Australia (uploaded by <a href=\"https:\/\/www.flickr.com\/photos\/29050464@N06\/\" target=\"_blank\">Peter D. Tillman<\/a>) is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/deed.en\" target=\"_blank\">CC BY 2.0 License<\/a>.<\/figcaption><\/figure>\n<figure style=\"width: 263px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image20-3.png\" alt=\"Rows of organisms, with plants and animals at the bottom and humans, angels, and God at top.\" width=\"263\" height=\"379\" \/><figcaption class=\"wp-caption-text\">Figure 2.2: The Great Chain of Being by Didacus Valades. Credit: <a href=\"https:\/\/commons.wikimedia.org\/w\/index.php?curid=1688250\" target=\"_blank\">Great Chain of Being<\/a> by Didacus Valades (Diego Valades 1579) and photographed by Rhetorica Christiana (via <a href=\"https:\/\/archive.org\/details\/rhetoricachristi00vala\/page\/n259\/mode\/2up\" target=\"_blank\">Getty Research<\/a>) is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\" target=\"_blank\">public domain<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 11.6515502929688pt;text-indent: 0pt\">Aristotle\u2019s <em>History of Animals<\/em> also placed animals in a hierarchy, ranking animals above plants due to what he claimed were their abilities to sense the world around them and to move. He also graded animals according to their modes of reproduction. Those giving birth to live young were placed above those who laid eggs. Warm-blooded animals ranked above invertebrates. This concept of \u201chigher\u201d and \u201clower\u201d organisms was expanded upon by scholars in the Medieval period to form the <em>Scala Naturae<\/em> (Latin for \u201cladder of being\u201d). This \u201cGreat Chain of Being,\u201d depicting a hierarchy of beings with God at the top and minerals at the bottom (Figure 2.2), was thought by medieval Christians to have been decreed by God; in this Great Chain, humans were placed closer to God than other species. Aristotle\u2019s works were rediscovered by Islamic scholars in the ninth century and translated into Arabic, Syriac, Persian, and later into Latin, becoming part of university curriculum in 13th-century Europe (Lindberg 1992), allowing Aristotle\u2019s works and ideas to influence other thinkers for 2,000 years.<\/p>\n<figure style=\"width: 251px\" class=\"wp-caption alignright\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image8-5.jpg\" alt=\"A person leading a giraffe on a leash, with text written in Arabic below.\" width=\"251\" height=\"375\" \/><figcaption class=\"wp-caption-text\">Figure 2.3: An image from Kit\u0101b al-\u1e25ayaw\u0101n (Book of the Animals) by Al-Jahiz. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Al-Jahiz.jpg\" target=\"_blank\">Al-Jahiz<\/a> by Al-Jahiz [in <a href=\"https:\/\/themuslimtimes.info\/2017\/02\/25\/al-jahizs-book-of-animals-the-transcendent-value-of-disgust\/\" target=\"_blank\">Kit\u0101b al-\u1e25ayaw\u0101n<\/a> (Book of the Animals), 15th century] is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\" target=\"_blank\">public domain<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 12.08837890625pt;text-indent: 0pt\">Science also owes a debt to many Arabic scholars. One such Islamic scholar and writer, who built upon the ideas of Aristotle, was Ab\u016b \u02bfUthman \u02bfAmr ibn Ba\u1e25r al-Kin\u0101n\u012b al-Ba\u1e63r\u012b \/ al-J\u0101\u1e25i\u1e93, known as Al-Jahiz (776\u2013868 CE), who authored over 200 books (El-Zaher 2018; Figure 2.3). His most well-known work was the seven-volume <em>Kitab al-Hayawan<\/em> or <em>Book of Animals<\/em>, in which he described over 350 species in zoological detail. Importantly, Al-Jahiz introduced the idea and mechanisms of biological evolution 1,000 years before Darwin proposed the concept of <strong>natural selection<\/strong> in 1859 (Love 2020). For instance, Al-Jahiz wrote about the struggle for existence, the transformation of species over time, and environmental factors that influence the process, all ideas that were later espoused by western European scientists in the 19th century. Al-Jahiz wrote:<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.891006pt;margin-right: 12.0884pt;text-indent: 0.648994pt;text-align: left;padding-left: 40px\">Animals engage in a struggle for existing, and for resources, to avoid being eaten, and to breed. Environmental factors influence organisms to develop new characteristics to ensure survival, thus transforming them into new species. Animals that survive to breed can pass on their successful characteristics to their offspring. [Masood 2009]<\/p>\n<figure style=\"width: 335px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image9-7.png\" alt=\"A person with a full beard and turban looks into the distance.\" width=\"335\" height=\"389\" \/><figcaption class=\"wp-caption-text\">Figure 2.4: Drawing of Ibn al-Haytham. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Ibn_al-Haytham.png\" target=\"_blank\">Ibn al-Haytham<\/a> by Sopianwar is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\" target=\"_blank\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.891006469726562pt;margin-right: 12.08837890625pt;text-indent: 0.648994445800781pt\">Another important early Islamic scientist is Ibn al-Haytham (965\u20131040), a 10th-century Islamic scholar who contributed a great deal to our understanding of optics and how human vision works (Figure 2.4; Lindberg 1992, 177\u2013180). Born in what is now Iraq, al-Haytham was a scholar of many disciplines, including mathematics, physics, mechanics, astronomy, philosophy, and medicine. He authored some 200 books in his lifetime and was an expert on Aristotle\u2019s natural philosophy, logic, and metaphysics. In relation to evolution, al-Haytham\u2019s methodology of investigation\u2014specifically, using experiments to verify theory\u2014is similar to what later became known as the modern scientific method. He is most famous for discovering the laws of reflection and refraction over 1,000 years ago and inventing the camera obscura, which was incredibly important for the eventual development of photography. His work is credited for its influence on astronomy, mathematics, and optics, inspiring Galileo, Johannes Kepler, and Sir Isaac Newton (Tasci 2020). As an inspirational scientific figure, al-Haytham was celebrated in 2016 by UNESCO as a trailblazer and the founder of modern optics (Figure 2.5). An International Year of Light was named in his honor and a scholarly conference on his contributions was held to coincide with the 1,000th anniversary of the publication of his <em>Kit\u0101b al-Man\u0101\u1e93ir<\/em> (Book of Optics; UNESCO.org 2015).<\/p>\n<figure style=\"width: 239px\" class=\"wp-caption alignright\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image16-2.jpg\" alt=\"Labeled diagram of the eye and optic nerves.\" width=\"239\" height=\"399\" \/><figcaption class=\"wp-caption-text\">Figure 2.5: Diagram of the Human Eye by Ibn al-Haytham. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:I.A._Haitham,_Diagram_of_the_eye,_16th_century_Wellcome_L0011969.jpg\" target=\"_blank\">Diagram of the eye<\/a> by Ibn Al [Alhazen] Haitham (16th Century) has been modified (cropped) and is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/legalcode\" target=\"_blank\">CC BY 4.0 License<\/a>. This image is available from <a href=\"https:\/\/wellcomeimages.org\/\" target=\"_blank\">Wellcome Images<\/a> 3044 (under the photo number L0011969).<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0.891006469726562pt;margin-right: 12.08837890625pt;text-indent: 0.648994445800781pt\">The writings of these Islamic scholars as well as similar scientific texts from other cultures were unknown to or unacknowledged by Western scientists until recently. Fortunately, many science teachers are now incorporating this content into their classes (Love 2020).<\/p>\n<h2 class=\"import-Normal\" style=\"background-color: transparent;margin-left: 1.364006042480469pt;margin-right: 0pt;text-indent: 0pt\">Western European Evolutionary Thought<\/h2>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.836006164550781pt;margin-right: 0.0257568359375pt;text-indent: 0pt\">Although there have been many different scientific traditions throughout world history, a new global discourse around science emerged in Western Europe in the 19th century. Europeans pointed to the continuing expansion of their colonial power\u2014as well as their military and technological success\u2014as evidence of the efficacy of Western science, which came to dominate on a global scale (Elshakry 2010). The movement toward a global science centred in Western Europe began with formulation of the <strong>Scientific Method<\/strong>.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0.0257568359375pt;text-indent: 0pt\">The Scientific Method was first codified by Francis Bacon (1561\u20131626), an English politician who was likely influenced by the methods of inquiry established by Ibn al-Haytham centuries prior (Tbakhi &amp; Amr 2007). Bacon has been called the founder of <strong>empiricism<\/strong> for proposing a system for weighing the truthfulness of knowledge based solely on inductive reasoning and careful observations of natural phenomena. Ironically, he died as a result of trying to scientifically observe the effects of cold on the putrefaction of meat. On a journey out of London, he purchased a chicken and stuffed it with snow for observation, catching a chill in the process. One week later, he died of bronchitis (Urbach, Quinton, &amp; Lea 2023).<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0.0257568359375pt;text-indent: 0pt\">The second important development with regard to evolution was the concept of a <strong>species<\/strong>. John Ray (1627\u20131705), an English parson and naturalist, was the first person to publish a biological definition of species in his <em>Historia Plantarum<\/em> (<em>History of Plants),<\/em> a three volume work published in 1686, 1688, and 1704<em>. <\/em>Ray defined a <em>species<\/em> as a group of morphologically similar organisms arising from a common ancestor. However, we now define a species as a group of similar organisms capable of producing fertile offspring. In keeping with the scientific method, Ray classified plants according to similarities and differences that emerged from observation. He claimed that any seed from the same plant was the same species, even if it had slightly different traits.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.836006164550781pt;margin-right: 4.403076171875pt;text-indent: 0pt\">The modern period of biological classification began with the work of Carl von Linne (\u201cCarolus Linnaeus\u201d) (1707\u20131778), a Swedish scientist who laid the foundations for the modern scheme of taxonomy used today. He established the system of <strong>binomial nomenclature<\/strong>, in which a species of animal or plant receives a name consisting of two terms: the first term identifies the genus to which it belongs and the second term identifies the species. His original <em>Systema<\/em> <em>Naturae<\/em>, published in 1736, went through several editions. By the tenth edition in 1758, mammals incorporated primates, including apes and humans, and the term <em>Homo sapiens <\/em>was introduced to signify the latter (Paterlini 2007).<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.495002746582031pt;margin-right: 4.97509765625pt;text-indent: 0pt\">Georges-Louis Leclerc, Comte de Buffon (1707\u20131788), was a prominent French naturalist whose work influenced prominent scientists in the second half of the 18th century. Buffon's idea that species change over time became a cornerstone of modern evolutionary theory. His technique of comparing similar structures across different species, called <strong>comparative anatomy<\/strong>, is still in use today in the study of evolution. He published 36 volumes of <em>Histoire<\/em> <em>Naturelle<\/em> during his lifetime and heavily influenced two prominent French thinkers who were to have significant impacts on our understanding of evolution, Georges Cuvier and Jean-Baptiste Lamarck.<\/p>\n<figure style=\"width: 455px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image23-2.jpg\" alt=\"Historic painting of person with short wavy hair next to drawing of a mastodon skeleton.\" width=\"455\" height=\"302\" \/><figcaption class=\"wp-caption-text\">Figure 2.6: Cuvier with one of his drawings of a fossil quadruped. Credit: Cuvier and a fossil quadruped original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\" target=\"_blank\">CC BY-NC-SA 4.0 License<\/a>. [Includes <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Georges_Cuvier_3.jpg\" target=\"_blank\">Georges Cuvier 3<\/a> by <a href=\"https:\/\/en.wikipedia.org\/wiki\/Fran%C3%A7ois-Andr%C3%A9_Vincent\" target=\"_blank\">Fran\u00e7ois-Andr\u00e9 Vincent<\/a> (artist), <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\" target=\"_blank\">public domain<\/a>; <a href=\"https:\/\/freesvg.org\/mammoth-skeleton\" target=\"_blank\">Mammoth skeleton<\/a> in <a href=\"https:\/\/freesvg.org\/by\/OpenClipart\" target=\"_blank\">OpenClipart<\/a>, <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/cc0\/\" target=\"_blank\">public domain (CC0)<\/a>.]<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.594001770019531pt;margin-right: 1.4913330078125pt;text-indent: 0pt\">Georges Cuvier (1769\u20131832) was a paleontologist and comparative anatomist (Figure 2.6). One of his first major contributions to the field of evolution was proof that some species had become <strong>extinct <\/strong>through detailed and comprehensive analyses of large fossil quadrupeds (Moore 1993, 111). The idea of extinction was not new, but it was challenging to demonstrate if a fossil species was truly extinct or still had living relatives elsewhere. It was also challenging in that it ran counter to religious beliefs of the time. The Bible\u2019s Book of Genesis was interpreted as saying that all species had been created by God in the seven days it took to create the world and that all created species have survived to this day. Extinction was interpreted as implying imperfection, suggesting God\u2019s work was flawed. Also, given that the Earth was calculated to have been created in 4004 B.C.E., based on biblical genealogies, there would not have been enough time for species to disappear (Moore 1993, 112).<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 1.4913330078125pt;text-indent: 0pt\">Cuvier was so knowledgeable in this field that he became famous for his ability to reconstruct what an extinct animal looked like from fragmentary remains. He demonstrated that fossil mammoths differed from similar living creatures, such as elephants. His many examples of fossils telling the stories of animals that lived and then disappeared were taken as incontrovertible proof of extinctions (PBS 2001). Where Cuvier went awry was his hypothesis of how extinction worked and its causes. As part of his study of comparative anatomy, Cuvier made observations of stratified layers of rock, or sediment, each containing different species. From this, he drew conclusions that species were \u201cfixed\u201d and did not evolve, but then went extinct, and that different assemblages of fossils occurred at different times in the past, as evidenced by the sedimentary layers (Moore 1993, 118). Cuvier explained this through a theory of <strong>catastrophism<\/strong>, which stated that successive catastrophic deluges (akin to Biblical floods) swept over parts of the Earth periodically, exterminating all life. When the waters receded from a particular region, lifeforms from unaffected regions would repopulate the areas that were destroyed, giving rise to a new layer of species that looked different from the layer below it. This theory implied that species were fixed in place and did not evolve and that the Earth was young. In fact, Cuvier postulated that the last catastrophe was a deluge he believed occurred five to six thousand years ago, paving the way for the advent of humans (Moore 1993, 118). Cuvier\u2019s catastrophism became part of an ongoing and vociferous debate between two schools of geology. The catastrophists believed the present state of the earth was the consequence of a series of violent catastrophes of short duration, while the uniformitarians thought it was the result of slow acting geological forces that continue to shape the earth.<\/p>\n<figure style=\"width: 379px\" class=\"wp-caption alignright\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image13-2.jpg\" alt=\"Horizontal layers of rock rest on vertical layers of rock.\" width=\"379\" height=\"303\" \/><figcaption class=\"wp-caption-text\">Figure 2.7: Siccar Point, Aberdeen, UK. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Siccar_Point.jpg\" target=\"_blank\">Siccar Point<\/a> by <a href=\"https:\/\/www.geograph.org.uk\/profile\/139\" target=\"_blank\">Anne Burgess<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\" target=\"_blank\">CC BY-SA 2.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.495002746582031pt;margin-right: 1.47552490234375pt;text-indent: 0pt\">James Hutton (1726\u20131797) was one prominent proponent of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_830\">uniformitarianism<\/a><\/strong>. Based on evidence he found at sites in his native Scotland, Hutton argued that the Earth was much older than previously thought. Examining the geology of Siccar Point, a cliff site on the eastern coast of Scotland (Figure 2.7), Hutton concluded that the intersection of the vertical and horizontal rocks represented a gap in time of many millions of years, during which the lower rocks had been deformed and eroded before the upper layers were deposited on top. From this, Hutton argued sediments are deposited primarily in the oceans, where they become strata, or layers of sedimentary rock. Volcanic action uplifts these strata to form mountains, which are then subject to erosion from rain, rivers, and wind, returning sediment to the oceans (Moore 1993, 121). Hutton\u2019s <em>Theory of the Earth <\/em>(1788) demanded vast periods of time (known as \u201cdeep time\u201d) for such slow-working forces to shape the earth. At the time, he was heavily criticized for this view, as it contradicted the biblical version of the history of creation.<\/p>\n<figure style=\"width: 391px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image18-3.jpg\" alt=\"A cross-section of a volcanic eruption showing different types of rock that make up the volcano.\" width=\"391\" height=\"249\" \/><figcaption class=\"wp-caption-text\">Figure 2.8: The frontispiece from Charles Lyell's Principles of Geology (2nd American edition, 1857), showing the origins of different rock types. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Lyell_Principles_frontispiece.jpg\" target=\"_blank\">Lyell Principles frontispiece<\/a> by Charles Lyell (Principles of Geology, 2nd American edition, 1857) is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\" target=\"_blank\">public domain<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.495002746582031pt;margin-right: 1.47552490234375pt;text-indent: 0pt\">Another Scotsman, who was to become a highly influential geologist and a close friend of Darwin, was Charles Lyell (1797\u20131875). Lyell was originally a lawyer who began his studies of Geology at Oxford under the tutelage of catastrophist William Buckland, from whom he diverged when Buckland tried to find physical evidence of Noah\u2019s flood from the Christian Bible. Lyell was instead intent on establishing geology as a science based on observation. Building upon Hutton\u2019s ideas (published 50 years earlier), Lyell traveled throughout Europe, documenting evidence of uniformitarianism. During his travels, he catalogued evidence of sea level rise and fall and of volcanoes positioned atop much older rocks. He also found evidence of valleys formed through erosion, mountains resulting from earthquakes, and volcanic eruptions that had been witnessed or documented in the past (University of California Berkeley Museum of Paleontology n.d.). Lyell also espoused the principle that \u201crocks and strata (layers of rock) increase in age the further down they are in a geological sequence. Barring obvious upheavals or other evidence of disturbance, the same principle must apply to any fossils contained within the rock. The lower down in a sequence of rocks a fossil is, the older it is likely to be (Wood 2005, 12).\u201d<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0.495002746582031pt;margin-right: 1.47552490234375pt;text-indent: 0pt\">Lyell published the first edition of his three-volume <em>Principles of Geology <\/em>in 1830\u20131833 (Figure 2.8). It established geology as a science, underwent constant revisions as new scientific evidence was discovered, and was published in 12 editions during Lyell\u2019s lifetime. In it, he espoused the key concept of uniformitarianism\u2014that \"the present is the key to the past.\u201d What this meant was that geological remains from the distant past can be explained by reference to geological processes now in operation and directly observable.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 1.83465576171875pt;text-indent: 0pt\">Jean-Baptiste Lamarck (1744\u20131829) was the first Western scientist to propose a mechanism explaining why and how traits changed in species over time, as well as to recognize the importance of the physical environment in acting on and shaping physical characteristics. Lamarck\u2019s view of how and why species changed through time, known as the \u201cTheory of Inheritance of Acquired Characteristics,\u201d was first presented in the introductory lecture to students in his invertebrate zoology class at the Museum of Natural History in Paris in 1802 (Burkhardt 2013). It was based on the idea that as animals adapted to their environments through the use and disuse of characteristics, their adaptations were passed on to their offspring through reproduction (Figure 2.9). Lamarck was right about the environment having an influence on characteristics of species, as well as about variations being passed on through reproduction. He simply had the mechanism wrong.<\/p>\n<p><img class=\"aligncenter\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image14-5.png\" alt=\"Giraffes with necks of different heights reach to eat leaves.\" width=\"419\" height=\"244\" \/><\/p>\n<figure style=\"width: 404px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image11-7.png\" alt=\"Illustration of three giraffes with necks of different heights.\" width=\"404\" height=\"391\" \/><figcaption class=\"wp-caption-text\">Figure 2.9a-b: Inheritance of Acquired Characteristics and Natural Selection. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-3\/\" target=\"_blank\">Lamarckian Evolution (Figure 4.2A and 4.2B)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 1.86676025390625pt;text-indent: 0pt\">Lamarck\u2019s theory involved a three-step process. Step one involves an animal experiencing a radical change in its environment. Step two is the animal (either individual or species) responding with a new kind of behaviour. Step three is how the behavioural change results in morphological (meaning physical) changes to the animal that are successfully passed on to subsequent generations (Ward 2018, 8). Lamarck\u2019s most famous example was the proposition that giraffes actively stretched their necks to reach leaves on tall trees to eat. Over their lifetimes, the continuation of this habit resulted in gradual lengthening of the neck. These longer necks were then passed on to their offspring. Lamarck's theory was disproved when evolutionary biologist August Weismann published the results of an experiment involving mice (Figure 2.10). Weismann amputated the tails of 68 mice and then successively bred five generations of them, removing the tails of all offspring in each generation, eventually producing 901 mice, all of whom had perfectly healthy long tails in spite of having parents whose tails were missing (Weismann 1889).<\/p>\n<figure style=\"width: 551px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image6-5.png\" alt=\"Mice with cut-off ails breed healthy offspring with full length tails.\" width=\"551\" height=\"385\" \/><figcaption class=\"wp-caption-text\">Figure 2.10: Weismann\u2019s mouse-tail experiment showing that offspring do not inherit traits that the parents acquired during their lifetimes. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-3\/\" target=\"_blank\">Weismann\u2019s mouse-tail experiment (Figure 4.3)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.527999877929688pt;margin-right: 0.20892333984375pt;text-indent: 0pt\">How giraffes actually ended up with long necks is a different story. In an environment where the food supply is higher off the ground, and perhaps less available to competing species, giraffes who happened to have slightly longer necks (due to random individual variation and genetic mutation) would be more likely to survive. These giraffes would then be able to reproduce, passing along the slight variation in neck length that would allow their offspring to do the same. Over time, individuals with longer necks would be overrepresented in the population, and neck lengths overall would increase among giraffes. Unfortunately, Lamarck\u2019s ideas challenged the scientific establishment of the time and were rejected. He was discredited and harassed \u201cto the point of loss of money, reputation, and then health\u201d (Ward 2018, 9).<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.527999877929688pt;margin-right: 0.4715576171875pt;text-indent: 0pt\">The final piece in the evolutionary puzzle leading up to the theory of natural selection was put forth by Thomas Malthus (1766\u20131834), who published <em>A<\/em><em>n Essay on Population <\/em>in 1798. Malthus lived in England during the time of the Industrial Revolution. It was a time of great poverty and misery when many people migrated from the countryside to squalid, disease-ridden cities to work extremely long hours in dangerous conditions in factories, coal mines, and other industrial workplaces. Birth rates were high and starvation and disease were rampant. Malthus struggled to explain why. His answer was basically the idea of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1788\">carrying capacity<\/a><\/strong>, an ecological concept still in use today. Malthus suggested the rate of population growth exceeded the rate of increase of the human food supply. In other words, people were outgrowing the available food crops. He also suggested that populations of animals and plants were naturally constrained by the food supply, resulting in reductions in population in times of scarcity, \u201crestraining them within the prescribed bounds\u201d (Moore 1993, 147). But, despite significant challenges, some individuals always survived. This was the key to later understandings of evolutionary change in species over time.<\/p>\n<h2 class=\"import-Normal\" style=\"background-color: transparent;margin-left: 1.331001281738281pt;margin-right: 0pt;text-indent: 0pt\">The Journey to Natural Selection<\/h2>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.527999877929688pt;margin-right: 7.171630859375pt;text-indent: 0pt\">In Western European thought, the individual most closely associated with evolution is Charles Darwin (1809\u20131882). However, as one can see from the individuals and ideas presented in the prior section, he was not the first person to explore evolution and how it might work. In fact, Darwin built upon and synthesized many of the ideas\u2014from geology to biology, ecology, and economy\u2014discussed above. He was simply in the right place at the right time. If he had not worked out his ideas when he did, someone else would have. As a matter of fact, as noted below, someone else did, forcing Darwin to publicly reveal his theory.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 7.171630859375pt;text-indent: 0pt\">Darwin continued his observations and experiments during his formal education, culminating in his graduation from Cambridge in 1831, at which point he was invited to become a gentleman naturalist for a British Royal Navy surveying mission of the globe aboard the H.M.S. <em>Beagle<\/em>. It is worth noting that Darwin was only 22 years old and the captain\u2019s third choice for the position (Costa 2017), but he proved extremely curious and methodical. The mission departed in December of 1831 and returned five years later (Figure 2.11). During this time, Darwin produced copious notebooks, observations, drawings, and reflections on the natural phenomena he encountered and the experiments he performed.<\/p>\n<figure style=\"width: 780px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image22-5.png\" alt=\"The voyage of the Beagle throughout the world.\" width=\"780\" height=\"329\" \/><figcaption class=\"wp-caption-text\">Figure 2.11: Map of the voyage of the H.M.S. Beagle. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available.<\/a> Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Voyage_of_the_Beagle-de.svg\" target=\"_blank\">Voyage of the Beagle-de<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Succu\" target=\"_blank\">Succu<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 3.4952392578125pt;text-indent: 0pt\">Discussing all of Darwin\u2019s work aboard the <em>Beagle <\/em>is beyond the scope of this chapter, but his primary interests were in cataloguing new varieties of plant and animal life and examining the geology of the places the ship made landfall. Part of Darwin\u2019s success with regard to both ventures was due to his extreme seasickness, which began before the ship even left Plymouth Harbour. It never let up, encouraging Darwin to go ashore at every available opportunity. \u201cIn fact, of the nearly five years of the voyage, Darwin was actually on board the ship for just a year and a half altogether\u201d (Costa 2017, 18).<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.527999877929688pt;margin-right: 4.93707275390625pt;text-indent: 0pt\">During the voyage, the young Darwin tried to make sense of what he saw through the lens of the scientific paradigms he held when he left England, but he continually made observations that challenged these paradigms. For example, while the <em>Beagle<\/em> crewmen were charting the coast of Argentina, Darwin conducted fieldwork on land. There he observed species that were new to him, like armadillos. He also collected fossils, including those of extinct armadillos. Meaning, he had found both <strong>extant <\/strong>and extinct members of the same species in the same geographic location, which challenged the theory of catastrophism put forth by Cuvier, who argued that each variant of an animal, living or extinct, was its own distinct species (Moore 1993, 144). Darwin also observed geographic variation in the same species all along the east coast of South America, from Brazil to the southern tip of Argentina. He noted that some species were found in multiple localities and differed from place to place. Those living closer to each other exhibited only slight variations, while those living further apart might be catalogued as entirely different species if one did not know better.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.693000793457031pt;margin-right: 14.136962890625pt;text-indent: 0pt\">He made similar observations in the Galapagos Islands located off the northwest coast of Ecuador, with regard to giant tortoises and finches (Figure 2.12). A local resident of the islands explained to Darwin that each island had its own variety of tortoise and that locals could discern which island a tortoise came from simply by looking at it. Darwin noted other such examples in both plants and animals, meaning geographic variation was occurring on separate, neighbouring islands.<\/p>\n<figure style=\"width: 684px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image15-4.jpg\" alt=\"Hood Island tortoises have saddle-backed shells; Isabella Island, dome-shaped; Pinta Island, intermediate.\" width=\"684\" height=\"528\" \/><figcaption class=\"wp-caption-text\">Figure 2.12: Variation in giant tortoises in the Galapagos Islands. Credit: Giant Tortoises of the Galapagos Islands original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Mary Nelson and Katie Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0.67529296875pt;text-indent: 0pt\">Prevailing views of time argued that variations in living species, and even the fossil armadillos and the living armadillos, were the result of separate creation events. According to this view, each variation, no matter how slight, was a different species. Challenging these ideas would mean challenging not only catastrophism, but the <strong>Fixity of Species<\/strong> and other well-accepted ideas of the time. Darwin was aware that he was a young, unestablished naturalist. He was also aware of the ruin that befell Lamarck when his theories were rejected. Lastly, Lyell, who was a good friend of Darwin\u2019s, rejected evolution altogether. It is no wonder that Darwin published a great deal about the geological and fossil data he collected when he returned from the voyage, but not his early hypotheses about evolution.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.627006530761719pt;margin-right: 0pt;text-indent: 0pt\">Upon Darwin\u2019s return to England, it took another twenty years of data collection and experimentation before he was ready to share his conclusions about evolution. Much of this work was conducted at Down House, his home of forty years, where he performed all sorts of experiments that laid the groundwork for his ideas about evolution. Darwin\u2019s home was his laboratory, and he engaged the help of his children, neighbours, friends, and servants in collecting, dissecting, and experimenting. At one point in the 1850s, sheets of moistened paper covered with frogs eggs lined the hallways of the house, while flocks of sixteen different pigeon breeds cooed outside, glass jars filled with salt water and floating seeds filled the cellar, and the smell of dissected pigeon skeletons pervaded the air inside the house. There were also ongoing experiments in the yard, including piles of dissected flowers, beekeeping, and fenced-off plots of land where seedlings were under study. Darwin was a keen experimental scientist, observer, and a prolific writer and presenter of scientific papers. He regarded his work as \u201cone long argument\u201d that never really ended. In fact, Darwin published ten books after <em>On the Origin of Species<\/em>, addressing such far-ranging topics as animal behaviour, orchids, and domestication, among others (Costa 2017).<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.627006530761719pt;margin-right: 0pt;text-indent: 0pt\">Darwin may not have published <em>Origins<\/em> in 1859 had it not been for receiving a paper in June of 1858 from Alfred Russel Wallace, an English naturalist working in Malaysia, espousing the same ideas. Wallace had sent the paper to Darwin asking if it was worthy of publication and requesting he forward it to Lyell and the English botanist, Joseph Hooker. Darwin wrote to Lyell and Hooker about Wallace\u2019s paper, entitled <em>On the Tendency of Varieties to Depart Indefinitely from the Original Type<\/em>. In recognition that both Wallace and Darwin had arrived at the same discovery, a \u201cjoint\u201d paper composed of four parts (none of them actually coauthored) was read to the Linnaean Society by Lyell, then secretary of the Society, on July 1, 1858, and published on August 20. Darwin published <em>On the Origin of Species <\/em>15 months later. (The original composite paper read before the Linnaean society is available to read for free from the Alfred Russell Wallace Website, on the <a href=\"https:\/\/wallacefund.myspecies.info\/content\/1858-darwin-wallace-paper\" target=\"_blank\">1858 Darwin-Wallace paper<\/a> page.)<\/p>\n<h3 class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.726005554199219pt;margin-right: 0pt;text-indent: 0pt\"><strong>The Mechanism of Natural Selection <\/strong><\/h3>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.693000793457031pt;margin-right: 4.15203857421875pt;text-indent: 0pt\">Let us take a moment here to explore the mechanism of natural selection in more detail. Before we begin, it is important to recognize that Darwin defined evolution as descent with modification, by which he meant that species share a common ancestor yet change over time, giving rise to new species. Descent with modification refers to the fact that offspring from two parents look different from each of their parents, and from each other, meaning they descend with slight differences (\u201cmodifications\u201d). If you have ever observed a litter of puppies or a field of flowers and stopped to examine each individual closely, you have seen that each differs from the next, and none look exactly like their parents. These variations are random, not specific, and may or may not be present in the following generations.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.693000793457031pt;margin-right: 4.15203857421875pt;text-indent: 0pt\">Darwin struggled to explain why some slight differences were preserved over time, while others were not. He turned to what he knew of animal breeding (<strong>artificial selection<\/strong>) for an explanation (Richards 1998). Darwin bred different breeds of pigeons at Down House, carefully documenting phenotypic differences across generations, including slight anatomical variations he observed through dissection. He also grew and crossbred species of flowers and dissected those too. Darwin was also very fond of hunting and of hunting dogs. In an early draft of his theory on speciation, he used greyhounds as an example of adaptation and selection, \u201cnoting how its every bone and muscle, instinct and habit, were fitted to run down hare (rabbits) (University of Cambridge n.d.).\u201d In each case of plant and animal breeding Darwin observed, he noted that humans were selecting variants in each generation that had characteristics humans desired (i.e., sweetness of fruits, colours of flowers, fur type and colour of animals). Breeders then continually bred plants and animals with the desired variants, over and over again. These small changes added up over time to create new species of plants and breeds of animals. Darwin also noted that artificial selection does not necessarily render plants or animals better adapted to their original environments. The characteristics humans desire often result in plants less likely to survive in the wild and animals more likely to suffer from certain behavioural or health problems. One has only to examine high rates of hip dysplasia in several modern breeds of dogs to observe what Darwin was referring to.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.693000793457031pt;margin-right: 4.15203857421875pt;text-indent: 0pt\">From his studies of artificial selection, Darwin drew the conclusion that nature also acts upon variations among members of the same species. Instead of human intervention, the forces of nature, such as heat, cold, predation, disease, and now climate change, determine which offspring, with which variants, survive and reproduce. These individuals then pass down these favourable variants to their own offspring. In this way, nature selects for traits that are beneficial within a particular environment and selects against traits that are disadvantageous within a particular environment. Over many generations, populations of a species become more and more adapted (or, in evolutionary terms, \u201cfit\u201d) for their specific environments. Darwin named this process natural selection.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.693000793457031pt;margin-right: 4.15203857421875pt;text-indent: 0pt\">This theory explained the variations in tortoises Darwin had observed years earlier in the Galapagos Islands (see Figure 2.12). Tortoises who lived on larger islands with lush vegetation to feed on were larger than those on smaller islands. They also had shorter necks and dome-shaped shells as their food was close to the ground. Tortoises on smaller, drier islands fed on cacti, which grew much taller. These tortoises had longer necks, longer front legs, and saddle-shaped shells, which allowed them to successfully stretch to reach the edible cactus pads that grew on the tops of the plants. How did these observable differences in the two tortoise populations emerge? Darwin would argue that, over time, small, random variations in the tortoises were differentially selected for by the distinct natural environments on different islands.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.693000793457031pt;margin-right: 4.15203857421875pt;text-indent: 0pt\">In addition to the biogeographical evidence Darwin offered from his research aboard the <em>Beagle<\/em>, as well as the evidence he documented from the artificial selection of plants and animals, he also relied, where possible, on fossil evidence. One example, mentioned above, were the fossil findings of extinct armadillos in Argentina in the same locations as living armadillos. Unfortunately, as Darwin himself noted, the geological record was incomplete, most often missing the transitional fossil forms that bridge extinct and living species. That issue has since been resolved with scientific research in geochronology and paleontology, among other fields. It is now well-established that life is far more ancient than was believed in Darwin\u2019s time and that these ancient forms of life were the ancestors to all life on this planet (Kutschera &amp; Niklas 2004).<\/p>\n<h2 class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\">What Darwin was Missing<\/h2>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.527999877929688pt;margin-right: 2.886962890625pt;text-indent: 0pt\">Although the theory of evolution by natural selection gained traction in scientific circles in the decades after Darwin\u2019s publication of <em>Origins<\/em>, he was never able to discover the mechanisms that caused variation within members of the same species or the means by which traits were inherited. This began later in 1892 with the publication of <em>The Germ-Plasm: A Theory of Heredity<\/em> by August Weismann, the same Weismann of the mouse tail experiment presented earlier in this chapter. In his book, Weissman proposed a theory of germ-plasm, which was a precursor to the later discovery and understanding of DNA. Weismann specialized in cytology, a branch of biology devoted to understanding the function of plant and animal cells. Germ-plasm, he proposed, was a substance in the germ cells (what we would call gametes, or sex cells, today) that carried hereditary information. He predicted that an offspring inherits half of its germ-plasm from each of its parents, and claimed that other cells (e.g. somatic, or body, cells) could not transmit genetic information from parents to offspring. This thereby erased the possibility that acquired traits (which he argued resided in somatic cells) could be inherited (Zou 2015). This contribution to evolutionary theory was an important step toward understanding genetic inheritance, but a connection between genetics and evolution was still lacking.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 2.886962890625pt;text-indent: 0pt\">A series of lectures by a deceased Augustinian monk named Gregor Mendel (1822\u20131884), originally published in 1865, changed that perspective (Moore 1993, 285). Although Darwin was unknown to Mendel, he began a series of experiments with pea plants shortly after the publication of Darwin\u2019s <em>Origins<\/em>, aiming to add to evolutionary understandings of heredity. As Mendel bred different generations of pea plants that had differences in seed shape and colour, pod shape and colour, flower position, and stem length, he documented consistent expression of some variations over others in subsequent generations. He meticulously documented the statistics of each crossing of plants and the percentages of <strong>phenotypes<\/strong> that resulted, eventually discovering the concept of dominance and recessiveness of characteristics, as will be seen in chapter 3. The recognition of the importance of Mendel\u2019s work began with its rediscovery by Hugo de Vries and Carl Correns, both of whom were working on hypotheses regarding heredity in plants and had arrived at conclusions similar to Mendel\u2019s. Both published papers supporting Mendel\u2019s conclusions in 1900 (Moore 1993). Research into the inheritance of characteristics continued through the next three decades, and by the close of the 1930s, no major scientific questions remained regarding the transmission of heredity through <strong>genes<\/strong>, although what genes did and what chemicals they were made of were still under investigation.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 2.886962890625pt;text-indent: 0pt\">The <strong>Modern Synthesis <\/strong>refers to the merging of Mendelian genetics with Darwinian evolution that took place between 1930 and 1950. The basic principles of the synthetic theory were influenced by scientists working in many different fields, including genetics, zoology, biology, paleontology, botany, and statistics. Although there were differences of opinion among them, evolution came to be defined as changes in allele frequencies within populations. Genetic mutations, changes in the genetic code that are the original source of variation in every living thing, were believed to be random, the sources of phenotypic variation, and transmitted through sexual reproduction. These assertions were supported by a growing body of field and laboratory research, as well as new work in mathematics in the field of population genetics that defined evolution as numerical changes in gene frequencies within an interbreeding population from one generation to the next (Corning 2020). These changes in gene frequencies were argued to be the result of natural selection, mutation, migration (<strong>gene flow<\/strong>), and <strong>genetic drift<\/strong>, or random chance. Empirical research and mathematics demonstrated that very small selective forces acting over a relatively long time were able to generate substantial evolutionary change, including speciation (Plutynski 2009). Thus, the Modern Synthesis encompassed both <strong>microevolution<\/strong>, which refers to changes in gene frequencies between generations within a population, and <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1507\">macroevolution<\/a><\/strong>, longer-term changes in a population that can eventually result in speciation, wherein individuals from different populations are no longer able to successfully interbreed and produce viable offspring.<\/p>\n<figure style=\"width: 267px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image10-2.jpg\" alt=\"A white man with short hair dressed in a white shirt and dark tie.\" width=\"267\" height=\"355\" \/><figcaption class=\"wp-caption-text\"><em>Figure 2.13: Theodosius Dobzhansky (1943). Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Dobzhansky_no_Brasil_em_1943.jpg\" target=\"_blank\">Dobzhansky no Brasil em 1943<\/a> by unknown creator via <a href=\"https:\/\/www.flickr.com\/photos\/celycarmo\/\" target=\"_blank\">Cely Carmo<\/a> at Flickr is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\" target=\"_blank\">public domain<\/a>.<\/em><\/figcaption><\/figure>\n<p><em>Genetics and the Origin of Species<\/em>, published in 1937 by Theodosius Dobzhansky (Figure 2.13), was a cornerstone of the modern synthesis, applying genetics to the study of natural selection in wild populations, appealing to both geneticists and field biologists. Dobzhansky was interested in <strong>speciation<\/strong>, particularly in finding out what kept one species distinct from another and how speciation occurred. His research involved fruit flies, the species <em>Drosophila pseudoobscura<\/em>. At the time he began in the 1920s, biologists assumed all members of the same species had nearly identical genes. Dobzhansky traveled from Canada to Mexico capturing wild members of <em>D.<\/em><em>pseudoobscura<\/em>, discovering that different populations had different combinations of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_738\">alleles<\/a><\/strong> (forms of a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1458\">gene<\/a><\/strong>) that distinguished them from other populations, even though they were all members of the same species. What, then, led to the creation of new species? Dobzhansky realized it was sexual selection. Members of the same species are more likely to live among their own kind and to recognize, and prefer, them as mates. Over time, as a result of random mutations, natural selection in a given environment, and <strong>genetic drift<\/strong>, meaning random changes in allele frequencies, members of the same population accumulate mutations distinct to their own <strong>gene pool<\/strong>, eventually becoming genetically distinct from other populations. What this means is that they have become a new <strong>species.<\/strong><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.527999877929688pt;margin-right: 2.886962890625pt;text-indent: 0pt\">From these studies, Dobzhansky and others developed the Bateson-Dobzhansky-Muller model, also known as Dobzhansky-Muller model (Figure 2.14). It is a model of the evolution of genetic incompatibility. Combining genetics with natural selection, the model is important in understanding the role of reproductive isolation during speciation and the role of natural selection in bringing it about. Due to sexual selection (mate preference), populations can become reproductively isolated from one another. Eventually, novel mutations may arise and be selected for in one or both populations, rendering members of each genetically incompatible with the other, resulting in two distinct species.<\/p>\n<figure style=\"width: 601px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image4-4.jpg\" alt=\"Dobzhansky-Muller Model producing hybrids with incompatible mutations. See caption for image details.\" width=\"601\" height=\"348\" \/><figcaption class=\"wp-caption-text\">Figure 2.14: The Dobzhansky-Muller Model: In the ancestral population the genotype is AABB. When two populations become isolated from each other, new mutations can arise. In one population uppercase A evolves into lowercase a, and in the other uppercase B evolves into lowercase b. When the two populations hybridize, it is the first time a and b interact with each other. When these alleles are incompatible, they represent Dobzhansky-Muller incompatibilities. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Bateson-Dobzhansky-Muller_model._.jpg\" target=\"_blank\">Bateson-Dobzhansky-Muller model<\/a> by OrientationEB is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\" target=\"_blank\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<div class=\"textbox\">\n<h2 class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\">Special Topic: Evolution and Natural Selection Observable Today<\/h2>\n<figure style=\"width: 339px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image19-3.jpg\" alt=\"Side view of a brown speckled lizard laying on a plastic lawn chair.\" width=\"339\" height=\"226\" \/><figcaption class=\"wp-caption-text\">Figure 2.15: Puerto Rican Crested Anole photographed in Picard, Dominica. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Anolis_cristatellus_in_Picard,_Dominica-2012_02_15_0339.jpg\" target=\"_blank\">Anolis cristatellus in Picard, Dominica-2012 02 15 0339<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Postdlf\" target=\"_blank\">Postdif<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/deed.en\" target=\"_blank\">CC BY-SA 3.0 Unported License<\/a>.<\/figcaption><\/figure>\n<p>Although this chapter primarily focuses on the past, it is important to remember that natural selection and evolution are still ongoing processes. Climate change, deforestation, urbanization, and other human impacts on the planet are influencing evolution among many contemporary species of plants and animals. One such example occurs among crested anoles (<em>Anolis cristatellus<\/em>), small lizards of the Caribbean jungle that are increasingly making their home in cities (Figure 2.15).<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\">As urban sprawl continues across the planet, shrinking the availability of wilderness habitat, many wild species have come to make their homes in cities. \u201cUrbanization has dramatically transformed landscapes around the world\u2014changing how animals interact with nature, creating \"heat islands\" with higher temperatures, and hurting local biodiversity. Yet many organisms survive and even thrive in these urban environments, taking advantage of new habitats created by humans (National Science Foundation 2023). A recent example of lizards in Puerto Rico demonstrates evolution happening quickly in both behaviour and genes that has come about as a result of the pressures of urban life (Winchell Et al. 2023). Crested anoles, who once lived only in forests, now scurry around towns and cities throughout the Caribbean. As a result of having to sprint across large open spaces, like hot streets and parking lots, they have developed longer limbs. City-living lizards also now sport longer toe pads with special scales that allow them to cling to smooth surfaces, like windows and walls (as well as the plastic patio furniture pictured in Figure 2.15), rather than to the rough surfaces of bark and rock that their forest-living relatives climb. These adaptations enhance their ability to escape predators and survive in cities.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\">Researchers were curious to see if these changes were the result of genetic changes in urban populations, so they captured 96 male lizards in three Puerto Rican regions and compared their genomes to each other and to forest specimens in each location. They found that members of the three city-living populations were genetically distinct from each other, as well as from forest populations in their respective regions. In total, 33 genes in the urban lizards\u2019 genomes were different from their forest-living counterparts and were linked to urbanization. These changes are estimated to have occurred just within the last 30 to 80 generations, suggesting that selective pressures related to survival in urban environments is strong. As study coauthor Kristen Winchell put it, \u201cWe are watching evolution as it is unfolding\u201d (National Public Radio 2023). (If you are interested in hearing more about the study, see \u201c<a href=\"https:\/\/www.pnas.org\/post\/podcast\/lizards-adapt-urban-living\" target=\"_blank\">How Lizards Adapt to Urban Living<\/a>,\u201d an episode of Science Sessions, a free podcast from the Proceedings of the National Academy of Sciences (PNAS 2023) featuring Dr. Winchell and her work.)<\/p>\n<\/div>\n<h2 class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\">Misconceptions About Evolution Through Natural Selection<\/h2>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.836006164550781pt;margin-right: 3.1103515625pt;text-indent: 0pt\">After many years of teaching about evolution and natural selection, it continues to surprise me how many misconceptions exist about how the process works. If you do a web image search for \u201chuman evolution,\u201d the following image is likely to appear (Figure 2.16).<\/p>\n<figure style=\"width: 605px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image2-6.png\" alt=\"Six increasingly upright figures walk in one direction.\" width=\"605\" height=\"222\" \/><figcaption class=\"wp-caption-text\">Figure 2.16: An artist\u2019s visual representation of the process of human evolution. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Human_evolution_scheme.svg\" target=\"_blank\">Human evolution scheme<\/a> by M. Garde is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 3.0211181640625pt;text-indent: 0pt\">What is wrong with this picture? First, it implies that humans evolved from chimpanzees, which is incorrect. Although, as primates, we share a common ancestor very far back in time, we split from other primates, including our closest relatives, the nonhuman apes, several million years ago. This image also suggests that evolution is gradual and progressive; that it is intentional and directional; and that there is an end to it\u2014a stopping point. As you will be learning, evolution takes place in fits and starts, depending on the physical environment, changes in climate, food supply, predation, reproductive success, and other factors. It is also not intentional, in the sense that there is no predetermined end; in fact, if environmental conditions change, species can evolve in different directions or even go extinct. Evolution also does not necessarily progress in the same direction over time. One example is the eel-like creature <em>Qikiqtania wakei<\/em> that lived 375 million years ago. It was originally a fish that evolved to walk on land, then evolved to live back in the water. Early tetrapods like <em>Qikiqtania<\/em> were likely spending more and more time out of the water during this period. The arrangement of bones and joints in their fins was starting to resemble arms and legs, which would have allowed them to prop themselves up in shallow water and survive on mudflats. <em>Qikiqtania\u2019<\/em>s skeletal morphology, however, suggests that it then evolved from having rudimentary fingers and toes back to fins that allowed them to again swim in open water (Stewart Et al. 2022).<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.869003295898438pt;margin-right: 11.6299438476562pt;text-indent: 0pt\">There is also the misperception that natural selection can create entirely new anatomical structures out of thin air in response to changes in environmental pressures. For example, when asked if they can think of ways in which modern humans are continuing to evolve biologically, students often postulate that, as a result of climate change, humans might rapidly develop gills, webbed hands and feet, and learn to breathe underwater in response to rising sea levels. Unfortunately, natural selection can only act on slight variations in anatomy that are already present, and we have no rudimentary physiological system for breathing underwater. Given that natural selection can only act upon existing variation, humans have evolved in such a way that many parts of our bodies are prone to injury. Our knees are one example. The anterior cruciate ligament (ACL) in our knees is \u201cvulnerable to tearing in humans because our upright bipedal posture forces it to endure much more strain than it is designed to\u201d (Lents 2018, 23). When our ancestors made the transition from quadrupedalism to upright walking, we shifted from four bent legs to two straight legs, relying more on our bones than our muscles to support our weight. This is functional for normal walking and running in a straight line, but sudden shifts in direction and momentum, combined with the sizes and weights of modern humans, result in tears in an ACL that is simply not strong enough to bear the stress. If evolution had the capability to engineer a knee from scratch, it would look quite different, and any ligaments involved would likely be larger, stronger, and more flexible. For an interesting look at what anatomically modern humans might look like if we had evolved to withstand the stresses our bodies undergo in our present environment, see \u201c<a href=\"https:\/\/www.radiotimes.com\/tv\/documentaries\/this-is-what-the-perfect-body-looks-like-according-to-science\/\" target=\"_blank\">This is what the perfect body looks like - according to science<\/a>,\u201d which was proposed by biological anthropologist Alice Roberts (Harrison 2018).<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.836006164550781pt;margin-right: 9.61920166015625pt;text-indent: 0pt\">Another misperception about evolution is that some species are \u201cmore evolved\u201d than others. Every species currently alive on the planet today is the result of millennia of natural selection that has rendered current members of that species well-adapted to their respective environments. Humans are no more \u201cevolved\u201d than fruit flies or yeast. What sets us apart are our cultural and technological abilities, which have allowed us to successfully survive in a wide variety of physical environments, many of which are now becoming too hot, too wet, or too dry to sustain human life without a great deal of technological intervention (IPCC 2022).<\/p>\n<figure style=\"width: 366px\" class=\"wp-caption alignright\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image5-3.jpg\" alt=\"A male dragonfly with a light blue body, transparent wings, and black markings rests on a twig.\" width=\"366\" height=\"282\" \/><figcaption class=\"wp-caption-text\">Figure 2.17: Adult male Common Whitetail Dragonfly, <a href=\"https:\/\/commons.wikimedia.org\/wiki\/Libellula_lydia\" target=\"_blank\">Libellula lydia<\/a>. Credit: <a href=\"https:\/\/www.cirrusimage.com\/dragonfly_common_whitetail.htm\" target=\"_blank\">Common Whitetail Dragonfly \u2013 Plathemis lydia<\/a> by Bruce Marlin is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.5\" target=\"_blank\">CC BY-SA 2.5 License<\/a>.<\/figcaption><\/figure>\n<p>There is also some confusion about what \u201cfitness\u201d actually means and a failure to grasp that it changes as environmental conditions change. Evolutionary \u201cfitness\u201d is different from physical fitness. \u201cFitness\u201d in evolutionary terms refers to an individual\u2019s ability to survive and reproduce viable offspring who also survive and reproduce. Evolutionary fitness and reproductive success are highly dependent on specific environmental conditions, which can shift over time, greatly affecting the relative fitness of individuals in a population. Recent research on the impacts of climate change on dragonflies will serve to illustrate the point (Figure 2.17).<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.748001098632812pt;margin-right: 3.8743896484375pt;text-indent: 0.594001770019531pt\">Pictured here is a male dragonfly, who, you will notice, has distinctive black markings on its wings. This is due to melanization. Males control breeding, and those with more ornamentation tend to attract more mates and to successfully ward off male competitors. Higher levels of melanization, however, have negative consequences for males in warming climates. The black markings absorb heat, elevating body temperatures, which can cause overheating, reduce male fighting ability, and even lead to death (Moore Et al. 2021). Females are not as adversely affected because they spend more time in shaded areas, while males are more often flying in sunlit areas, fending off rivals. However, as highly melanized males become less viable, wing colouration is undergoing selection in males. In other words, what constitutes being \u201cfit\u201d for males has changed, favouring those who have fewer of the black markings and, therefore, are less negatively impacted by warming temperatures. Note that natural selection acts on individuals, \u201cselecting\u201d those who happen to be fit for particular environmental conditions at a particular point in time. Evolution, though, happens at the level of the population. If the climate continues to warm, populations of dragonflies who inhabit warming areas will increasingly exhibit less ornamentation in males.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.858001708984375pt;margin-right: 5.50946044921875pt;text-indent: 0pt\">Lastly, natural selection can only act on characteristics that influence reproductive success. Deleterious traits that have nothing to do with one\u2019s ability to reproduce and successfully rear offspring to reproductive age will continue to be passed on. For example, the author of this chapter is a natural redhead, and redheads are predisposed genetically to a number of conditions that can negatively affect health (Colliss Harvey 2015), but some of these conditions are not diagnosed until later in life. One example is Parkinson\u2019s disease (Chen Et al. 2017), which is a degenerative neurological disorder. The average age of diagnosis of Parkinson\u2019s is 60 years of age, meaning redheads may encounter such a diagnosis well past childbearing age, having already passed on the genetic predisposition. Thus, Parkinson\u2019s disease cannot be selected out from the redhead family tree.<\/p>\n<\/div>\n<h2 class=\"__UNKNOWN__\">Are We Still Evolving?<\/h2>\n<div class=\"__UNKNOWN__\">\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">After reading this chapter, many students are curious to know if humans are still evolving. The answer is yes. As a species, we continue to respond to selective pressures biologically and culturally. This final section will focus on three contemporary examples of human evolution. Before beginning, let\u2019s review the conditions necessary for natural selection to operate on a trait. First, the trait must be heritable, meaning it is transmitted genetically from generation to generation. There must also be variation of the trait within the population and the trait must influence reproductive success. Three examples of traits that meet these criteria are immunity to the Human Immunodeficiency Virus (HIV), height, and wisdom teeth (Andrews, Kalinowski, &amp; Leonard 2011).<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">AIDS is a potentially fatal infectious disease caused by HIV, a zoonosis believed to be derived from Simian Immunodeficiency Viruses (SIVs) found in chimpanzees and monkeys and most likely transmitted to humans through the butchering of infected animals (Sharp &amp; Hahn 2011). In total, 40 million people have died from AIDS-related illnesses since the start of the global epidemic in the 1980s. There were 38.4 million people around the world living with AIDS as of 2021, including 1.5 million new cases and 650,000 deaths in that year alone (UNAIDS 2021). A disease causing this level of morbidity and mortality represents a major selective pressure, especially given that infection can occur before birth (Goulder Et al. 2016), thereby affecting future reproductive success.<\/p>\n<figure style=\"width: 323px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image17-7.png\" alt=\"A political map of Europe and North Africa associated with percentages ranging from 0% to 16.4%.\" width=\"323\" height=\"391\" \/><figcaption class=\"wp-caption-text\">Figure 2.19: Map of CCR5-delta32 allele distribution. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-11\/\" target=\"_blank\">Map of CCR5-delta32 allele distribution (Figure 16.10)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Katie Nelson is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available.<\/a> [Includes <a href=\"https:\/\/pixabay.com\/vectors\/europe-map-western-political-32847\/\" target=\"_blank\">Europe Map Western Political 32847<\/a> by <a href=\"https:\/\/pixabay.com\/users\/clker-free-vector-images-3736\/\" target=\"_blank\">Clker-Free-Vector-Images<\/a>, <a href=\"https:\/\/pixabay.com\/service\/terms\/#license\" target=\"_blank\">Pixabay License<\/a>; data from Solloch et al. 2017.]<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The majority of people in the world are highly susceptible to HIV infection, but some are not. These latter individuals are homozygous for a rare, recessive allele at the CCR5 locus that makes them immune to HIV. Heterozygotes who inherit a single copy of this allele are more resistant to infection and, when infected, the disease takes longer to progress in the event that they are infected. The mechanism by which the allele prevents infection involves a 32-base pair deletion in the DNA sequence of the CCR5 gene, creating a nonfunctioning receptor on the surface of the cell that prevents HIV from infecting the cell. The allele is inherited as a simple Mendelian trait, and there is variation in its prevalence, ranging as high as 14% of the population in northern Europe and Russia (Novembre, Galvani, and Slatkin 2005; see Figure 2.19). What is interesting about the allele\u2019s geographic distribution is that it does not map onto parts of the world with the highest rates of HIV infection (Figure 2.20), suggesting that AIDS was not the original selective pressure favouring this allele.<\/p>\n<figure style=\"width: 498px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image7-8.png\" alt=\"World map with different HIV infection rates throughout the world.\" width=\"498\" height=\"253\" \/><figcaption class=\"wp-caption-text\">Figure 2.20: World map of countries shaded according to their HIV\/AIDS adult prevalence rate in 2020. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available.<\/a> Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:World_map_of_countries_by_HIV-AIDS_adult_prevalence_rate_%282020%29.svg\" target=\"_blank\">World map of countries by HIV-AIDS adult prevalence rate (2020)<\/a> by LuccaSSC has been designated to the <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/cc0\/\" target=\"_blank\">public domain (CC0 1.0)<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Given its current geographic distribution, the bubonic plague, which ravaged Europe repeatedly from the 14th to the 19th centuries (Pamuk 2007), was initially proposed as the selective agent. Subsequent research suggests smallpox, which killed up to 400,000 people annually in 18th-century Europe (Hays 2005), was more likely the selective pressure (Novembre, Galvani, &amp; Slatkin 2005). Given the mortality rates for smallpox (Crosby 2003), an allele that conferred immunity was highly advantageous, as it is for those faced with the threat of HIV infection today.<\/p>\n<p class=\"import-Normal\">Height is another example of a trait experiencing selective pressure. If you have ever toured a historical site, you have likely hit your head on a doorframe or become claustrophobic trying to squeeze down a narrow hallway under a lower-than-average ceiling. It is not your imagination. Humans have gotten taller in recent centuries. In fact, the average height of people in industrialized nations has increased approximately 10 centimetres in the past 150 years. This increase has been attributed to improvements in nutrition, sanitation, and access to medical care (Hatton 2014). But this is only part of the story.<\/p>\n<p class=\"import-Normal\">Height is highly heritable. Studies indicate 80% of variation in height within populations is due to genetics, with 697 different genetic variances identified as having an effect on adult stature (Devuyst 2014). Multiple studies also demonstrate a positive relationship between height and reproductive success for men (Andrews, Kalinowsky, &amp; Leonard 2011). This is primarily due to sexual selection and nonrandom mating, namely women\u2019s preferences for taller men, which may explain why height is one characteristic men often lie about on dating websites (Guadagno, Okdie, &amp; Kruse 2012). Sexual selection also plays out with regard to economic success in Western cultures, with taller men more likely to be in higher-level positions that pay well. Research demonstrates an inch of height is worth an additional $789 per year in salary, meaning a man who is six feet tall will earn on average $5,525 more per year than an identical man who is five foot five purely due to heightism bias (Gladwell 2007). Over the course of a career, this can add up to hundreds of thousands of dollars, likely allowing taller men to attract more potential mates, increasing their reproductive success.<\/p>\n<p class=\"import-Normal\">Wisdom teeth are also undergoing evolutionary pressure. Have you or anyone in your family had their wisdom teeth removed? While it can be a painful and expensive process, it is a common experience in Western nations. It begs the question as to why there is no longer room in our mouths for all of our teeth? Biological anthropologist Daniel Lieberman offers several reasons, including that modern humans are growing faster and maturing earlier, which could be leading to impaction if skeletal growth takes place faster than dental growth. He also argues that the soft diets many modern humans consume generate insufficient strain to stimulate enough growth in our jaws to accommodate all of our teeth. Lastly, as the human brain has expanded over the past hundreds of thousands of years, it is taking up more space in the skull, causing the jaw to shrink, leaving no room for third molars (Lieberman 2011).<\/p>\n<p class=\"import-Normal\">Conversely, do you know anyone whose wisdom teeth never came in? That is fairly common in some populations, suggesting evolutionary pressure favouring the absence of wisdom teeth has been culturally influenced. The oldest fossil evidence of skulls missing third molars was found in China and is 300,000 to 400,000 years old, suggesting the earliest mutation selecting against the eruption of wisdom teeth arose in Asia (Main 2013). Since that time, jaws have continued to decrease in size to the point they often cannot accommodate third molars, which can become impacted, painful, and even infected, a condition physical anthropologist Alan Main argues might have interfered with the ability to survive and reproduce in ancestral populations (Main 2013). As we have learned, a mutation that positively influences reproductive success\u2014such as being born without the trait to develop wisdom teeth\u2014would likely be selected for over time. Evidence in modern humans suggests that this is the case, with 40% of modern Asians and 45% of Native Alaskans and Greenlanders (populations descended from Asian populations) lacking wisdom teeth. The percentage among those of European descent ranges from 10 to 25% and for African Americans is 11% (Main 2013). Later chapters of this textbook emphasize that directional selection progresses along a particular path until the environment changes and a trait is no longer advantageous. In the case of wisdom teeth, the ability of modern dentistry to preempt impaction through surgery may, in fact, be what is preventing natural selection from doing away with wisdom teeth altogether.<\/p>\n<h2>Cultural Connections and Contemporary Implications<\/h2>\n<p>By the end of the Renaissance, knowledge inherited from Greek and Islamic scholars profoundly influenced how humans perceived nature and the scientific method itself. This period marked a major epistemic shift where the way of understanding and studying the natural world was evolving. Historical and religious worldviews were closely intertwined during this time: ancient ideas were often incorporated into theological frameworks, as exemplified by Archbishop James Ussher\u2019s famous calculation that the world was created on October 23, 4004 BC.<\/p>\n<p>The Enlightenment of the 17th and 18th centuries introduced rapid technological development and new philosophies of science. However, it also brought challenges. While curiosity about nature expanded, many thinkers continued to treat knowledge as fixed and immutable, anchored by biblical interpretation, which was often deemed too sacred to question.<\/p>\n<p>The second major scientific revolution emerged during the Industrial Era, influenced by European thinkers such as Charles Darwin, John Ray, Robert Hooke, James Hutton, and Jean-Baptiste Lamarck. This era saw groundbreaking advances in geology, paleontology, and biology. Concepts such as catastrophism, uniformitarianism, inheritance, and acquired characteristics reshaped humanity's understanding of the earth\u2019s history and the continuity of life.<\/p>\n<p>Yet, scientific ideas never exist in isolation as they are deeply interwoven with social and cultural life. As these thinkers sought to explain nature, evolution, and, by extension, human existence, their ideas inevitably intersected with religious worldviews. This long-standing entanglement and occasional tension between science and religion continue to shape how societies understand the origins of life today. For example, a 2023 Gallup Poll measuring <a href=\"https:\/\/news.gallup.com\/poll\/647594\/majority-credits-god-humankind-not-creationism.aspx\" target=\"_blank\">Americans\u2019 beliefs about human origins<\/a> revealed that 37% believed God created humans in their present form, 34% argued that humans developed through evolution with God\u2019s guidance, and only 24% of U.S. adults accepted the scientific theory of evolution. A similar reality exists in Canada, where <a href=\"https:\/\/researchco.ca\/2023\/04\/14\/evolution-2023\/#:~:text=By%20a%203%2Dto%2D1,within%20the%20last%2010%2C000%20years.\" target=\"_blank\">1 in 5 Canadians<\/a> believe God created human beings in their present form within the last 10,000 years.<\/p>\n<p>Consequently, these perspectives reflect two distinct ways of reconstructing the past. Science pursues truth through observation, testing, and empirical evidence, while religion offers meaning through faith, belief, and spiritual interpretation. As a result, attempts to understand the origins of humanity often follow divergent paths. But what happens when desire or ideology, rather than evidence, drives our reconstructions of the past of both nature and ourselves?<\/p>\n<h4>Discussion Questions<\/h4>\n<ul>\n<li style=\"font-weight: 400\">Can religion and science work collaboratively to deepen our understanding of life and the universe?<\/li>\n<li style=\"font-weight: 400\">What social tensions arise between human culture and scientific advancement?Can you provide some examples?<\/li>\n<li style=\"font-weight: 400\">How is modern society influencing our understanding of evolution happening today?<\/li>\n<li style=\"font-weight: 400\">Beyond religion, what other socio-cultural factors influence scientific understanding? Can you provide some examples?<\/li>\n<li style=\"font-weight: 400\">What does it mean when a culture limits the next generation\u2019s understanding to its own worldview? Is it possible for us to think or move beyond our cultural boundaries?<\/li>\n<\/ul>\n<h2 class=\"import-Normal\" style=\"margin-left: 1.364006042480469pt;text-indent: 0pt\">Key Developments in Evolutionary Thought<\/h2>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 482.25pt\">\n<tbody>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">4th century BCE<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Aristotle<\/p>\n<p class=\"import-Normal\">(384\u2013322 BCE)<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">\u201cFounder of Biology.\u201d Publishes <em>History of Animals<\/em>, a biological classification system of over 500 animals based on structure, physiology, reproduction, and behaviour. Also creates the \u201cGreat Chain of Being,\u201d ranking species and placing humans closest to God.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">8th\u20139th century CE<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Al-Jahiz<\/p>\n<p class=\"import-Normal\">(776\u2013868 CE)<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Writes seven-volume <em>Book of Animals<\/em>, which includes animal classifications and food chains. Introduces concept of biological evolution and its mechanisms.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1011\u20131021<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Ibn al-Haythem<\/p>\n<p class=\"import-Normal\">(965\u20131040 CE)<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">\u201cFather of Modern Optics.\u201d Uses experimental science to catalogue how vision works and discovers laws of reflection and refraction. Publishes <em>Book of Optics<\/em> and invents <em>camera obscura<\/em>, the foundation for modern photography.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1620<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Francis Bacon<\/p>\n<p class=\"import-Normal\">(1561\u20131626)<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">\u201cFather of Empiricism.\u201d Publishes <em>The Novum Annum<\/em>, formulating the scientific method based on observation and inductive reasoning.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1686<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">John Ray<\/p>\n<p class=\"import-Normal\">(1627\u20131705)<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">First to publish a biological definition of <em>species<\/em> in <em>History of Plants<\/em>.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1749<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Comte de Buffon<\/p>\n<p class=\"import-Normal\">(1707\u20131788)<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Publishes <em>Histoire Naturelle<\/em>, comparing anatomical structures across species using methods still in use today. Inspires Lamarck and Cuvier.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1758<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Carl von Linne<\/p>\n<p class=\"import-Normal\">(Carolus Linnaeus)<\/p>\n<p class=\"import-Normal\">(1707\u20131778)<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Introduces system of binomial nomenclature. Publishes <em>Systema Naturae<\/em>, the tenth edition of which introduces the designation <em>Homo sapiens <\/em>for humans.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1788<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">James Hutton<\/p>\n<p class=\"import-Normal\">(1726\u20131797)<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">\u201cFather of Geology.\u201d Publishes <em>Theory of the Earth<\/em>; introduces idea of Deep Time; explains how features of the earth were formed through the actions of rain, wind, rivers, and volcanic eruptions.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1798<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Thomas Malthus<\/p>\n<p class=\"import-Normal\">(1766\u20131834)<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Economist and \u201cFather of Statistics.\u201d Publishes <em>An Essay on Population<\/em>; introduces concept of carrying capacity; explains how populations outstrip the food supply, leaving some individuals to die off; inspires Darwin\u2019s idea of \u201cnatural selection.\u201d<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1809<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Jean-Baptiste Lamarck<\/p>\n<p class=\"import-Normal\">(1744\u20131829)<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Publishes theory of the Inheritance of acquired characteristics; is the first Western scientist to propose a mechanism explaining how traits change in species over time and to recognize the importance of the physical environment in acting on species and their survival.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1810<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Georges Cuvier<\/p>\n<p class=\"import-Normal\">(1769\u20131832)<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Paleontologist\/comparative anatomist; proved species went extinct; proposed the Theory of Catastrophism.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1830<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Charles Lyell<\/p>\n<p class=\"import-Normal\">(1797\u20131875)<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Establishes geology as a science. Publishes first edition of <em>The Principles of Geology <\/em>(1830\u201333); issuing 12 total editions in his lifetime, each updated according to new scientific data.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1858<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Alfred Russel Wallace<\/p>\n<p class=\"import-Normal\">(1823\u20131913)<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Sends scientific paper to Darwin titled \u201cOn the Tendency of Varieties to Depart Indefinitely from the Original Type,\u201d essentially espousing the concept of natural selection; a reading of the papers by both Wallace and Darwin to the Linnaean Society is conducted by Lyell.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1859<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Charles Darwin<\/p>\n<p class=\"import-Normal\">(1809\u20131882)<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Publishes <em>On the Origin of Species by Means of Natural Selection<\/em> (1859).<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1865<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Gregor Mendel<\/p>\n<p class=\"import-Normal\">(1822\u20131884)<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Publishes <em>Experiments in Plant Hybridization<\/em> (1865), outlining the fundamentals of genetic inheritance.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1889<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">August Weismann<\/p>\n<p class=\"import-Normal\">(1834\u20131914)<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Publishes <em>Essays Upon Heredity <\/em>(1889), disproving the inheritance of acquired characteristics. Publishes <em>The Germ Plasm <\/em>(1892), postulating an early idea of inheritance through sexual reproduction.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1937<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Theodosius Dobzhansky<\/p>\n<p class=\"import-Normal\">(1900\u20131975)<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">One of the founders of the Modern Synthesis of biology and genetics. Publishes <em>Genetics and the Origin of Species<\/em> (1937). Documents a genetic model of speciation through reproductive isolation.<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div class=\"textbox shaded\">\n<h2>Summary<\/h2>\n<p>Firstly, it is important to recognize that the global discourse on evolutionary thought emerged from a Western European colonial legacy; often centring eurocentric perspectives while overlooking other intellectual traditions. This legacy has resulted in a lasting influence in how the knowledge was\u2013and continues to be\u2013structured and understood.<\/p>\n<p>From its earliest ideas to today\u2019s genomic research, evolutionary thought has demonstrated that species, including our own, are not static, but are part of ongoing processes shaped by variation, natural selection, and shifting conditions. A persistent misconception is that evolution implies progress toward more advanced or \u2018better\u2019 forms; in reality, it reflects context-specific adaptations that enhance survival and reproduction. Humans exemplify this ongoing process, adapting through traits such as resistance to disease, tolerance of new foods, and responses to rapidly changing modern environments.<\/p>\n<h2 class=\"import-Normal\">Review Questions<\/h2>\n<ul>\n<li class=\"import-Normal\">Summarize the major scientific developments that led to the formulation of the theory of natural selection.<\/li>\n<li class=\"import-Normal\">Explain how natural selection operates and how it leads to evolution in populations.<\/li>\n<li class=\"import-Normal\">Explain the importance of genetics to an understanding of human evolution.<\/li>\n<li class=\"import-Normal\">Have you observed current examples of evolution taking place where you live? In which species? Which forces of evolution are involved?<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<h2 class=\"__UNKNOWN__\">Key Terms<\/h2>\n<div class=\"__UNKNOWN__\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.902000427246094pt;margin-right: 18.1800537109375pt;text-indent: 0.406997680664062pt\"><strong>Allele<\/strong>: A nonidentical DNA sequence found in the same gene location on a homologous chromosome, or gene copy, that codes for the same trait but produces a different phenotype.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.836006164550781pt;margin-right: 4.92626953125pt;text-indent: 0.34100341796875pt\"><strong>Artificial selection<\/strong>: The identification by humans of desirable traits in plants and animals, and the subsequent steps taken to enhance and perpetuate those traits in future generations.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.836006164550781pt;margin-right: 0.62152099609375pt;text-indent: 0.461997985839844pt\"><strong>Binomial nomenclature<\/strong>: A system of classification in which a species of animal or plant receives a name consisting of two terms: the first identifies the genus to which it belongs, and the second identifies the species.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 6.76727294921875pt;text-indent: 0pt\"><strong>Carrying capacity<\/strong>: The number of living organisms, including animals, crops, and humans, that a geographic area can support without environmental degradation.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.924003601074219pt;margin-right: 3.10675048828125pt;text-indent: 0.0879974365234375pt\"><strong>Catastrophism<\/strong>: The theory that the Earth\u2019s geology has largely been shaped by sudden, short-lived, violent events, possibly worldwide in scope. Compare to uniformitarianism.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.924003601074219pt;margin-right: 3.10675048828125pt;text-indent: 0.0879974365234375pt\"><strong>Comparative anatomy<\/strong>: Georges-Louis Leclerc\u2019s technique of comparing similar anatomical structures across different species.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.924003601074219pt;margin-right: 3.10675048828125pt;text-indent: 0.0879974365234375pt\"><strong>Creationism<\/strong>: The belief that the universe and all living organisms originate from specific acts of divine creation, as in the Biblical account, rather than by natural processes such as evolution.<\/p>\n<p class=\"import-Normal\" style=\"margin-right: 0.0257568359375pt\"><strong>Empiricism<\/strong>: The idea that all learning and knowledge derives from experience and observation. It became prominent in the 17th and 18th centuries in western Europe due to the rise of experimental science.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.858001708984375pt;margin-right: 53.6096496582031pt;text-indent: 0.44000244140625pt\"><strong>Evolution<\/strong>: In a biological sense, this term refers to cumulative inherited change in a population of organisms through time. More specifically, <em>evolution<\/em> is defined as a change in allele (gene) frequencies from one generation to the next among members of an interbreeding population.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 1.298004150390625pt;margin-right: 0pt;text-indent: 0pt\"><strong>Extant<\/strong>: Still in existence; surviving.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 1.199005126953125pt;margin-right: 19.8264770507812pt;text-indent: 0.0989990234375pt\"><strong>Extinct<\/strong>: Said of a species, family, or other group of animals or plants that has no living members; no longer in existence.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 1.199005126953125pt;margin-right: 19.8264770507812pt;text-indent: 0.0989990234375pt\"><strong>Fixity of <\/strong><strong>Species<\/strong>: The idea that a species, once created, remains unchanged over time.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.836006164550781pt;margin-right: 6.576171875pt;text-indent: 0pt\"><strong>Gene<\/strong>: A sequence of DNA that provides coding information for the construction of proteins.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0.836006164550781pt;margin-right: 6.576171875pt;text-indent: 0pt\"><strong>Genetic drift<\/strong>: Random changes in allele frequencies within a population from one generation to the next.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.836006164550781pt;margin-right: 6.576171875pt;text-indent: 0pt\"><strong>Gene flow<\/strong>: The introduction of new genetic material into a population through interbreeding between two distinct populations.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0.836006164550781pt;margin-right: 6.576171875pt;text-indent: 0pt\"><strong>Gene pool<\/strong>: The entire collection of genetic material in a breeding community that can be passed from one generation to the next.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0.836006164550781pt;margin-right: 6.576171875pt;text-indent: 0pt\"><strong>Genotype<\/strong>: The genotype of an organism is its complete set of genetic material\u2014its unique sequence of DNA. Genotype also refers to the alleles or variants an individual carries in a particular gene or genetic location.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.693000793457031pt;margin-right: 1.15521240234375pt;text-indent: 0.605003356933594pt\"><strong>Hybrid<\/strong>: Offspring of parents that differ in genetically determined traits.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.924003601074219pt;margin-right: 16.4979858398438pt;text-indent: 0.319000244140625pt\"><strong>Intelligent design<\/strong>: A pseudoscientific set of beliefs based on the notion that life on earth is so complex that it cannot be explained by the scientific theory of evolution and therefore must have been designed by a supernatural entity.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.594001770019531pt;margin-right: 24.672607421875pt;text-indent: 0.681999206542969pt\"><strong>Macroevolution<\/strong>: Large and often-complex changes in biological populations, such as species formation.<\/p>\n<p><strong>Microevolution<\/strong>: Changes in the frequency of a gene or allele in an interbreeding population.<\/p>\n<p><strong>M<\/strong><strong>odern synthesis<\/strong>: The mid\u201320th century merging of Mendelian genetics with Darwinian evolution that resulted in a unified theory of evolution.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.693000793457031pt;margin-right: 3.12261962890625pt;text-indent: 0.583000183105469pt\"><strong>Natural selection<\/strong>: The natural process by which the survival and reproductive success of individuals or groups within an interbreeding population that are best adjusted to their environment leads to the perpetuation of genetic qualities best suited to that particular environment at that point in time.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.693000793457031pt;margin-right: 19.8097534179688pt;text-indent: 0.605003356933594pt\"><strong>Phenotype<\/strong>: The detectable or visible expression of an organism\u2019s <em>genotype<\/em>.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.693000793457031pt;margin-right: 7.392578125pt;text-indent: 0.198005676269531pt\"><strong>Scientific method<\/strong>: A method of procedure that has characterized natural science since the 17th century, consisting of systematic observation, measurement, experimentation, and the formulation, testing, and modification of hypotheses.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0.858001708984375pt;margin-right: 2.66143798828125pt;text-indent: 0.0330047607421875pt\"><strong>Speciation<\/strong>: The process by which new genetically distinct species evolve from the main population, usually through geographic isolation or other barriers to gene flow.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0.858001708984375pt;margin-right: 2.66143798828125pt;text-indent: 0.0330047607421875pt\"><strong>Species<\/strong>: A group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding. The species is the principal natural taxonomic unit, ranking below a genus and denoted by a Latin binomial (e.g., <em>Homo sapiens<\/em>).<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0.495002746582031pt;margin-right: 1.47552490234375pt;text-indent: 0pt\"><strong>Uniformitarian<\/strong><strong>ism<\/strong>: The theory that changes in the earth's crust during geologic history have resulted from the action of continuous and uniform processes\u2014such as wind, precipitation, evaporation, condensation, erosion, and volcanic action\u2014that continue to act in the present. Compare to <strong>c<\/strong><em>atastrophism<\/em>.<\/p>\n<h2 class=\"import-Normal\">For Further Exploration<strong><br \/>\n<\/strong><\/h2>\n<p>Costa, James T. 2017. <em>Darwin\u2019s Backyard: How Small Experiments Led to a Big Theory<\/em>. New York: W.W. Norton.<\/p>\n<p>Darwin, Charles. 1905. <em>The Voyage of the Beagle<\/em>. (Originally published in 1839 as <em>Journal and Remarks<\/em>). [Author\u2019s note: Several editions exist with different publishers, including illustrated editions, paperback editions, and e-books.]<\/p>\n<p>Moore, John A. 1993. <em>Science as a Way of Knowing: The Foundations of Modern Biology<\/em>. Cambridge, MA: Harvard University Press.<\/p>\n<h2 class=\"import-Normal\">References<\/h2>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 29.0806274414062pt;text-indent: 0pt\">Al-Haytham, Ibn. 1011-1021. <em>Kit\u0101b al-Man\u0101\u1e93ir<\/em> (Book of Optics). Cairo, Egypt.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 29.0806274414062pt;text-indent: 0pt\">Al-Jahiz. 776\u2013868 CE. <em>Kitab al-Hayawan<\/em> (<em>Book of <\/em><em>Animals<\/em><em>).<\/em><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Andrews, Tessa M., Steven T. Kalinowski, and Mary J. Leonard. 2011. \u201cAre Humans Evolving? A Classroom Discussion to Change Students\u2019 Misconceptions Regarding Natural Selection.\u201d <em>Evolution: Education and Outreach<\/em> 4 (3): 456\u2013466.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Aristotle. 384-322 BCE. <em>History of <\/em><em>Animals<\/em><em>.<\/em><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Asghar, Anila, Salman Hameed, and Najme Kashani Farahani. 2014. \u201cEvolution in Biology Textbooks: A Comparative Analysis of Five Muslim Countries.\u201d Religion &amp; Education 41 (1). Accessed February 12, 2023. https:\/\/www.tandfonline.com\/doi\/abs\/10.1080\/15507394.2014.855081.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Associated Press. January 10, 2023. \u201cForest Lizards Have Genetically Morphed To Survive Life In The City, Researchers Say.\u201d <em>National Public Radio (NPR)<\/em>. 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Schwartzchild, and Xiang Gao. 2017. \u201cRed Hair, MC1R Variants, and Risk for Parkinson\u2019s Disease\u2014A Meta-Analysis.\u201d <em>Annals of Clinical and Translational Neurology<\/em> 4 (3): 212\u2013216.https:\/\/doi.org\/10.1002\/acn3.381.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 4.13275146484375pt;text-indent: 0pt\">Colliss Harvey, Jacky. 2015. <em>Red: A History of the Redhead<\/em>. 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E-copy available at https:\/\/www.esp.org\/books\/weismann\/essays\/facsimile\/.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 17.7549438476562pt;text-indent: 0pt\">Winchell, Kristen M., Shane C. Campbell-Staton, Jonathan B. Losos, and Anthony Geneva. 2023. \u201cGenome-Wide Parallelism Underlies Contemporary Adaptation In Urban Lizards.\u201d <em>PNAS<\/em> 120 (3): e2216789120. https:\/\/doi.org\/10.1073\/pnas.2216789120.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 17.7549438476562pt;text-indent: 0pt\">Wood, Bernard. 2005. <em>Human Evolution: A Very Short Introduction<\/em>. Oxford: Oxford University Press.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 17.7549438476562pt;text-indent: 0pt\">Zou, Yawen. 2015. \"The Germ-Plasm: a Theory of Heredity (1893), by August Weismann.\" <em>Embryo Project Encyclopedia<\/em>, January 26. Accessed February 18, 2023. https:\/\/embryo.asu.edu\/handle\/10776\/8284.<\/p>\n<\/div>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1695_1845\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1695_1845\"><div tabindex=\"-1\"><div class=\"__UNKNOWN__\">\n<div class=\"textbox\">\n<h6>Student contributors for this chapter from Salinda Hess' ANTH 203: Daphn\u00e9e-Tiffany Kirouac Millan, Davina Paradis, Jung Jin Kim, and Nathan Dennis<\/h6>\n<p>Learn more about <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/about-the-authors\/\">authors and editors<\/a>,<a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/student-contributors\/\"> Hess' student contributions<\/a>, and <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/versioning-history\/\">versioning history<\/a>.<\/p>\n<\/div>\n<p>&nbsp;<\/p>\n<div class=\"textbox textbox--learning-objectives\">\n<header class=\"textbox__header\">\n<h2 class=\"textbox__title\">Learning Objectives<\/h2>\n<\/header>\n<div class=\"textbox__content\">\n<ul>\n<li>Explain the relationship among genes, bodies, and organismal change.<\/li>\n<li>Discuss the shortcomings of simplistic understandings of genetics.<\/li>\n<li>Describe what is meant by the \"biopolitics of heredity.\"<\/li>\n<li>Discuss issues caused by misuse of ideas about adaptations and natural selection.<\/li>\n<li>Examine and correct myths about evolution.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<p class=\"import-Normal\">The Human Genome Project, an international initiative launched in 1990, sought to identify the entire genetic makeup of our species. For many scientists, it meant trying to understand the genetic underpinnings of what made humans uniquely human. James Watson, a codiscoverer of the helical shape of DNA, wrote that \u201cwhen finally interpreted, the genetic messages encoded within our DNA molecules will provide the ultimate answers to the chemical underpinnings of human existence\u201d (Watson 1990, 248). The underlying message is that what makes humans unique can be found in our <strong>genes<\/strong>. The Human Genome Project hoped to find the core of who we are and where we come from.<\/p>\n<p class=\"import-Normal\">Despite its lofty goal, the Human Genome Project\u2014even after publishing the entire human genome in January 2022\u2014could not fully account for the many factors that contribute to what it is to be human. Richard Lewontin, Steven Rose, and Leon Kamin (2017) argue that genetic determinism of the sort assumed by the Human Genome Project neglects other essential dimensions that contribute to the development and evolution of human bodies, not to mention the role that culture plays. They use an apt metaphor of a cake to illustrate the incompleteness of reductive models. Consider the flavour of a cake and think of the ingredients listed in the recipe. The recipe includes ingredients such as flour, sugar, shortening, vanilla extract, eggs, and milk. Does raw flour taste like cake? Does sugar, vanilla extract, or any of the other ingredients taste like cake? They do not, and knowing the individual flavours of each ingredient does not tell us much about what cake tastes like. Even mixing all of the ingredients in the correct proportions does not get us cake. Instead, external factors such as baking at the right temperature, for the right amount of time, and even the particularities of our evolved sense of taste and smell are all necessary components of experiencing the cake. Lewontin, Rose, and Kamin (2017) argue that the same is true for humans and other organisms.<\/p>\n<p class=\"import-Normal\">Knowing everything about cake ingredients does not allow us to fully know cake. Equally so, knowing everything about the genes found in our DNA does not allow us to fully know humans. Different, interacting levels are implicated in the development and evolution of all organisms, including humans. Genes, the structure of chromosomes, developmental processes, epigenetic tags, environmental factors, and still-other components all play key roles such that genetically reductive models of human development and evolution are woefully inadequate.<\/p>\n<p class=\"import-Normal\">The complex interactions across many levels\u2014genetic, developmental, and environmental\u2014explain why we still do not know how our one-dimensional DNA nucleotide sequence results in a four-dimensional organism. This was the unfulfilled promise of the inception of the Human Genome Project in the 1980s and 1990s: the project produced the complete DNA sequence of a human cell in the hopes that it would reveal how human bodies are built and how to cure them when they are built poorly. Yet, that information has remained elusive. Presumably, the knowledge of how organisms are produced from DNA sequences will one day permit us to reconcile the discrepancies between patterns in anatomical evolution and molecular evolution.<\/p>\n<p class=\"import-Normal\">In this chapter, we will consider multilevel evolution and explore evolution as a complex interaction between genetic and epigenetic factors as well as the environments in which organisms live. Next, we will examine the biopolitical nature of human evolution. We will then investigate problems that arise from attributing all traits to an adaptive function. Finally, we will address common misconceptions about evolution. The goal of this chapter is to provide you with the necessary toolkit for understanding the molecular, anatomical, and political dimensions of evolution.<\/p>\n<h2 class=\"import-Normal\">Evolution Happens at Multiple Levels<\/h2>\n<p class=\"import-Normal\">Following Richard Dawkins\u2019s publication of <em>The Selfish Gene <\/em>in 1976, the scientific imagination was captured by the potential of genomics to reveal how genes are copied by Darwinian selection. Dawkins argues that the genes in individuals that contribute to greater reproductive success are the units of selection. His conception of evolution at the molecular level undercuts the complex interactions between organisms and their environments, which are not expressed genomically but are nevertheless key drivers in evolution.<\/p>\n<p class=\"import-Normal\">By the 1980s, the acknowledgement among most biologists that even though genes construct bodies, genes and bodies evolve at different rates and with distinct patterns. This realization led to a renewed focus on how bodies change. The Evolutionary Synthesis of the 1930s\u20131970s had reduced organisms to their <strong>genotypes<\/strong> and species to their <strong>gene pools<\/strong>, which provided valuable insights about the processes of biological change, but it was only a first approximation. Animals are in fact reactive and adaptable beings, not passive and inert genotypes. Species are clusters of socially interacting and reproductively compatible organisms.<\/p>\n<figure style=\"width: 291px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"https:\/\/opentextbooks.concordia.ca\/explorations\/wp-content\/uploads\/sites\/57\/2023\/06\/image8-5.png\" alt=\"An asteroid hits the ocean. Pterodactyls fly among clouds in the foreground.\" width=\"291\" height=\"233\" \/><figcaption class=\"wp-caption-text\">Figure 3.1: A painting by Donald E. Davis representing the Chicxulub asteroid impact off the Yucatan Peninsula that contributed to the mass extinction that included the dinosaurs about 65 million years ago. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Chicxulub_impact_-_artist_impression.jpg\" target=\"_blank\">Chicxulub impact - artist impression<\/a> by Donald E. Davis, <a href=\"https:\/\/www.nasa.gov\/\" target=\"_blank\">NASA<\/a>, is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\" target=\"_blank\">public domain<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Once we accept that evolutionary change is fundamentally genetic change, we can ask: How do bodies function and evolve? How do groups of animals come to see one another as potential mates or competitors for mates, as opposed to just other creatures in the environment? Are there evolutionary processes that are not explicable by population genetics? These questions\u2014which lead us beyond reductive assumptions\u2014were raised in the 1980s by Stephen Jay Gould, the leading evolutionary biologist of the late 20th century (see: Gould 2003; 1996).<\/p>\n<p class=\"import-Normal\">Gould spearheaded a movement to identify and examine higher-order processes and features of evolution that were not adequately explained by population genetics. For example, <strong>extinction<\/strong>, which was such a problem for biologists of the 1600s, could now be seen as playing a more complex role in the history of life than population genetics had been able to model. Gould recognized that there are two kinds of extinctions, each with different consequences: background extinctions and mass extinctions. Background extinctions are those that reflect the balance of nature, because in a competitive Darwinian world, some things go extinct and other things take their place. Ecologically, your species may be adapted to its niche, but if another species comes along that\u2019s better adapted to the same niche, eventually your species will go extinct. It sucks, but it is the way of all life: you come into existence, you endure, and you pass out of existence. But mass extinctions are quite different. They reflect not so much the balance of nature as the wholesale disruption of nature: many species from many different lineages dying off at roughly the same time\u2014presumably as the result of some kind of rare ecological disaster. The situation may not be survival of the fittest as much as survival of the luckiest. The result, then, would be an ecological scramble among the survivors. Having made it through the worst, the survivors could now simply divide up the new ecosystem amongst themselves, since their competitors were gone. Something like this may well have happened about 65 million years ago, when a huge asteroid hit the Yucatan Peninsula, which mammals survived but dinosaurs did not (Figure 3.1). Something like this may be happening now, due to human expansion and environmental degradation. Note, though, that there is only a limited descriptive role here for population genetics: the phenomena we are describing are about organisms and species in ecosystems.<\/p>\n<p class=\"import-Normal\">Another question involved the disconnect between properties of <em>species<\/em> and the properties of <em>gene pools<\/em>. For example, there are upwards of 15 species of gibbons but only two species of chimpanzees. Why? There are upwards of 20 species of guenons but fewer than ten of baboons. Why? Are there genes for that? It seems unlikely. Gould suggested that species, as units of nature, might have properties that are not reducible to the genes in their cells. For example, rates of speciation and extinction might be properties of their ecologies and histories rather than their genes. Thus, relationships between environmental contexts and variability within a species result in degrees of resistance to extinction and affect the frequency and rates at which clades diversify (Lloyd &amp; Gould 1993). Consistent biases of speciation rates might well produce patterns of macroevolutionary diversity that are difficult to explain genetically and better understood ecologically. Gould called such biases in speciation rates <strong>species selection<\/strong>\u2014a higher-order process that invokes competition between species, in addition to the classic Darwinian competition between individuals.<\/p>\n<p class=\"import-Normal\">One of Gould\u2019s most important studies involved the very nature of species. In the classical view, a species is continually adapting to its environment until it changes so much that it is a different species than it was at the beginning of this sentence (Eldredge &amp; Gould 1972). That implies that the species is a fundamentally unstable entity through time, continuously changing to fit in. But suppose, argued Gould along with paleontologist Niles Eldredge, a species is more stable through time and only really adapts during periods of ecological instability and change. Then we might expect to find in the fossil record long equilibrium periods\u2014a few million years or so\u2014in which species don\u2019t seem to change much, punctuated by relatively brief periods in which they change a bit and then stabilize again as new species. They called this idea <strong>punctuated equilibria<\/strong>. The idea helps to explain certain features of the fossil record, notably the existence of small anatomical \u201cgaps\u201d between closely related fossil forms (Figure 3.2). Its significance lies in the fact that although it incorporates genetics, punctuated equilibria is not really a theory of genetics but one of types bodies in deep time.<\/p>\n<p class=\"import-Normal\">Punctuated equilibria is seen across taxa, with long periods in the fossil record representing little phenotypic change. These periods of stability are disrupted by shorter periods of rapid <strong>adaptation<\/strong>, the process through which populations of organisms become suited to living in their environments. Phenotypic changes are often coupled with drastic climatic or ecological changes that affect the milieu in which organisms live. For example, throughout much of hominin evolutionary history, brain size was closely associated with body size and thus remained mostly stable. However, changes occurred in average hominin brain size at around 100 thousand years ago, 1 million years ago, and 1.8 million years ago. Several hypotheses have been put forth to explain these changes, including unpredictability in climate and environment (Potts 1998), social development (Barton 1996), and the evolution of language (Deacon 1998). Evidence from the fossil record, paleoclimate models, and comparative anatomy suggests that the changes observed in hominin lineage result from biocultural processes\u2014that is, the coalescence of environmental and cultural factors that selected for larger brains (Marks 2015; Shultz, Nelson, &amp; Dunbar 2012).<\/p>\n<figure style=\"width: 461px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"https:\/\/opentextbooks.concordia.ca\/explorations\/wp-content\/uploads\/sites\/57\/2023\/08\/image5-8.png\" alt=\"Two graphs contrast phyletic gradualism and punctuated equilibria.\" width=\"461\" height=\"222\" \/><figcaption class=\"wp-caption-text\">Figure 3.2: Different ways of conceptualizing the evolutionary relationship between an earlier and a later species. With phyletic gradualism, species are envisioned transforming continually in a direct line over time. With punctuated equilibria species branch off at particular points over time.\u00a0 Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__\/\" target=\"_blank\">Phyletic gradualism vs. punctuated equilibria (Figure 2.12)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">In response to the call for a theory of the evolution of form, the field of <strong>evo-devo<\/strong>\u2014the intersection of evolutionary and developmental biology\u2014arose. The central focus here is on how changes in form and shape arise. An embryo matures by the stimulation of certain cells to divide, forming growth fields. The interactions and relationships among these growth fields generate the structures of the body. The <strong>hox genes<\/strong> that regulate these growth fields turn out to be highly conserved across the animal kingdom. This is because they repeatedly turn on and off the most basic genes guiding the animal\u2019s development, and thus any changes to them would be catastrophic. Indeed, these genes were first identified by manipulating them in fruit flies, such that one could produce a bizarre mutant fruit fly that grew a pair of legs where its antennae were supposed to be (Kaufman, Seeger, and Olsen 1990).<\/p>\n<p class=\"import-Normal\">Certain genetic changes can alter the fates of cells and the body parts, while other genetic changes can simply affect the rates at which neighbouring groups of cells grow and divide, thus producing physical bumps or dents in the developing body. The result of altering the relationships among these fields of cellular proliferation in the growing embryo is <strong>allometry<\/strong>, or the differential growth of body parts. As an animal gets larger\u2014either over the course of its life or over the course of macroevolution\u2014it often has to change shape in order to live at a different size. Many important physiological functions depend on properties of geometric area: the strength of a bone, for example, is proportional to its cross-sectional area. But area is a two-dimensional quality, while growing takes place in three dimensions\u2014as an increase in mass or volume. As an animal expands, its bones necessarily weaken, because volume expands faster than area does. Consequently a bigger animal has more stress on its bones than a smaller animal does and must evolve bones even thicker than they would be by simply scaling the animal up proportionally. In other words, if you expand a mouse to the size of an elephant, it will nevertheless still have much thinner bones than the elephant does. But those giant mouse bones will unfortunately not be adequate to the task. Thus, a giant mouse would have to change aspects of its form to maintain function at a larger size (see Figure 3.3).<\/p>\n<p class=\"import-Normal\"><img class=\"aligncenter\" src=\"https:\/\/opentextbooks.concordia.ca\/explorations\/wp-content\/uploads\/sites\/57\/2023\/08\/image6-6.png\" alt=\"Side-view of a mouse skeleton.\" width=\"515\" height=\"252\" \/><\/p>\n<figure style=\"width: 453px\" class=\"wp-caption aligncenter\"><img src=\"https:\/\/opentextbooks.concordia.ca\/explorations\/wp-content\/uploads\/sites\/57\/2023\/08\/image7-9.png\" alt=\"Side-view of an elephant skeleton.\" width=\"453\" height=\"326\" \/><figcaption class=\"wp-caption-text\">Figure 3.3: Mouse (top) and elephant (bottom) skeletons. Notice the elephant\u2019s bones are more robust when the two animals are the same size. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__\/\" target=\"_blank\">Mouse and elephant skeletons (Figure 2.13)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Physiologically, we would like to know how the body \u201cknows\u201d when to turn on and off the genes that regulate growth to produce a normal animal. Evolutionarily, we would like to know how the body \u201clearns\u201d to alter the genetic on\/off switch (or the genetic \u201cslow down\/speed up\u201d switch) to produce an animal that looks different. Moreover, since organisms differ from one another, we would like to know how the developing body distinguishes a range of normal variation from abnormal variation. And, finally, how does abnormal variation eventually become normal in a descendant species?<\/p>\n<p class=\"import-Normal\">Taking up these questions, Gould invoked the work of a British geneticist named Conrad H. Waddington, who thought about genetics in less reductive ways than his colleagues. Rather than isolate specific DNA sites to analyse their function, Waddington instead studied the inheritance of an organism\u2019s reactivity\u2014its ability to adapt to the circumstances of its life. In a famous experiment, he grew fruit fly eggs in an atmosphere containing ether. Most died, but a few survived somehow by developing a weird physical feature: a second thorax with a second pair of wings. Waddington bred these flies and soon developed a stable line of flies who would reliably develop a second thorax when grown in ether. Then he began to lower the concentration of ether, while continuing to selectively breed the flies that developed the strange appearance. Eventually he had a line of flies that would stably develop the \u201cbithorax\u201d <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1238\"><strong>phenotype<\/strong><\/a>\u2013the suite of traits of an organism\u2013even when there was no ether; it had become the \u201cnew normal.\u201d The flies had genetically assimilated the bithorax condition.<\/p>\n<p class=\"import-Normal\">Waddington was thus able to mimic the <strong>inheritance of acquired characteristics<\/strong>: what had been a trait stimulated by ether a few generations ago was now a normal part of the development of the descendants. Waddington recognized that while he had performed a selection experiment on genetic variants, he had not selected for particular traits. Rather, he helped produce the physiological tendency to develop particular traits when appropriately stimulated. He called that tendency <strong>plasticity<\/strong> and its converse, the tendency to stay the same even under weird environmental circumstances, <strong>canalization.<\/strong> Waddington had initially selected for plasticity, the tendency to develop the bithorax phenotype under weird conditions, and then, later, for canalization, the developmental normalization of that weird physical trait. Although Waddington had high stature in the community of geneticists, evolutionary biologists of the 1950s and 1960s regarded him with suspicion because he was not working within the standard mindset of reductionism, which saw evolution as the spread of genetic variants that coded for favourable traits. Both Waddington and Gould resisted contemporary intellectual paradigms that favoured reductive accounts of evolutionary processes. They conceived of evolution as an emergent process in which many external factors (e.g. climate, environment, predation) and internal factors (e.g., genotypes, plasticity, canalization) coalesce to produce the evolutionary trends that we observe in the fossil record and our genome.<\/p>\n<p class=\"import-Normal\">While Gould and Waddington both looked beyond the genome to understand evolution, the Human Genome Project\u2014an international project with the goal of identifying each base pair in the human genome in the 1990s\u2014generated a great deal of public interest in analyzing the human DNA sequence from the standpoint of medical genetics. Some of the rhetoric aimed to sell the public on investing a lot of money and resources in sequencing the human genome in order to show the genetic basis of heritable traits, cure genetic diseases, and learn what it means ultimately to be biologically human. However, the Human Genome Project was not actually able to answer those questions through the use of genetics alone, and thus a broader, more holistic account was required.<\/p>\n<p class=\"import-Normal\">This holistic account came from decades of research in human biology and anthropology, which understood the human body as highly adaptable, dynamic, and emergent. For example, in the early 20th century, anthropologist Franz Boas measured the skulls of immigrants to the U.S., revealing that environmental, not merely genetic, factors affected skull shape. The growing human body adjusts itself to the conditions of life, such as diet, sunshine, high altitude, hard labour, population density, how babies are carried\u2014any and all of which can have subtle but consistent effects upon its development. There can thus be no normal human form, only a context-specific range of human forms.<\/p>\n<p class=\"import-Normal\">However, what the human biologists called human adaptability, evolutionary biologists called developmental plasticity, and evidence quickly began to mount for its cause being <strong>epigenetic <\/strong>modifications to DNA. Epigenetic modifications are changes to how genes are used by the body (as opposed to changes in the DNA sequences; see Chapter 4). Scientific interest shifted from the focus of the Human Genome Project to the ways that bodies are made by evolutionary-developmental processes, including epigenetics. What is meant by \u201cepigenetic modification\u201d? Evolution is about how descendants diverge from their ancestors. Inheritance from parent to offspring is still critical to this process, which occurs through genetic recombination: the pairing of homologous chromosomes and sharing of genetic material during meiosis (see Chapter 4). However, in the 21st century, the link between evolution and inheritance has broadened with a clearer understanding of how environmental and developmental factors shape bodies and the expression of genes, including epigenetic inheritance patterns. While offspring inherit their genes through random assortment during meiosis, environmental factors also shape how genes are used. When these epigenetic modifications occur in germ cells, they can be passed onto offspring. In these cases, there is no change in the DNA sequence but rather in how genes are used by the body due to DNA methylation and the structure of chromosomes due to histone acetylation (see Chapter 4).<\/p>\n<p class=\"import-Normal\">In addition, we now recognize that evolution is affected by two other forms of intergenerational transmission and inheritance (in addition to genetics and epigenetics). These forms include behavioural variation and culture. That is, behavioural information can be transmitted horizontally (intragenerationally), permitting more rapid ways for organisms to adjust to the environment. And, then there is the fourth mode of transmission: the cultural or symbolic mode. It is proposed that humans are the only species that horizontally transmits an arbitrary set of rules to govern communication, social interaction, and thought. This shared information is symbolic and has resulted in what we recognize as \u201cculture\u201d: locally emergent worlds of names, words, pictures, classifications, revered pasts, possible futures, spirits, dead ancestors, unborn descendants, in-laws, politeness, taboo, justice, beauty, and story, all accompanied by practices and a material world of tools.<\/p>\n<p class=\"import-Normal\">Consequently our contemporary ideas about evolution see the evolutionary processes as hierarchically organized and not restricted to the differential transmission of DNA sequences into the next generation. While that is indeed a significant part of evolution, the organism and species are nevertheless crucial to understanding how those DNA sequences get transmitted. Further, the transmission of epigenetic, behavioural, and symbolic information play a complex role in perpetuating our genes, bodies, and species. In the case of human evolution, one can readily see that symbolic information and cultural adaptation are far more central to our lives and our survival today than DNA and genetic adaptation. It is thus misleading to think of humans passively occupying an environmental niche. Rather, humans are actively engaged in constructing our own niches, as well as adapting to them and using them to adapt. The complex interplay between a species and its active engagement in creating its own ecology is known as <strong>niche construction<\/strong>. If we understand <strong>natural selection<\/strong>\u2013the process by which populations adapt to their specific environments\u2013as the effects that environmental context has on the reproductive success of organisms, then niche construction is the process through which organisms shape their own selective pressures.<\/p>\n<div class=\"textbox\">\n<h2>Dig Deeper: Moving Beyond Genetic Determinism<\/h2>\n<p>Contemporary evolutionary biology and anthropology increasingly emphasize that genes operate within dynamic regulatory networks rather than acting as isolated determinants. As <a href=\"https:\/\/www.zotero.org\/google-docs\/?zoqFM1\" target=\"_blank\">Carroll (2005)<\/a> and <a href=\"https:\/\/www.zotero.org\/google-docs\/?C6NEFg\" target=\"_blank\">Wray (2007)<\/a> demonstrate, evolutionary change often arises not from mutations in structural genes but in their regulation\u2014the timing, intensity, and location of gene expression. Such regulatory evolution can explain major anatomical and physiological innovations without invoking large genetic divergences. This view reframes evolution as an outcome of organizational complexity where genetic, developmental, and environmental processes intersect. This systems-level understanding also resonates with anthropological frameworks of biocultural embodiment, which recognize that social and ecological experiences can become biologically inscribed in the body. <a href=\"https:\/\/www.zotero.org\/google-docs\/?AROEum\" target=\"_blank\">Meaney\u2019s (2001)<\/a>\u00a0 foundational epigenetic research focuses on maternal care in rats, presenting how nurturing behaviour modifies the expression of stress-response genes. This biological effect can persist into subsequent generations.<\/p>\n<p>Recent human studies continue to expand this insight. <a href=\"https:\/\/www.zotero.org\/google-docs\/?r3ZGNw\" target=\"_blank\">Goldman &amp; Sterner (2023)<\/a> demonstrate how environmental exposures, inequality, and psychological stress influence the pace of biological aging, showing epigenetic modifications reflect the lived conditions of bodies over time. In Canada, this relationship between environment, history, and biology has profound implications. A 2023 scoping review on Canadian Indigenous populations and the epigenetic effects of intergenerational trauma <a href=\"https:\/\/www.zotero.org\/google-docs\/?NEGUdK\" target=\"_blank\">(Schafte &amp; Bruna, 2023)<\/a> documents measurable biological patterns associated with colonial violence, displacement, and systemic inequity. By dissecting the obesity patterns in the Indigenous youth populations, the researchers present a clear connection between the parents who attended residential schools and biological health issues in their children years later. This holistic understanding of epigenetics shows an \u201cembodied transmission of trauma and ill health across generations\u201d (2023, p.9), underscoring that the effects of colonialism are not merely social but are biologically embodied, carried forward through mechanisms of gene regulation and stress physiology.<\/p>\n<p>Understanding heredity as a process of interaction and regulation rather than genetic determinism opens the door to rethinking evolution as a flexible, context-driven phenomenon. Just as social experiences and ecological conditions can shape patterns of gene expression, environmental pressures can also influence the structure and behaviour of genomes across generations. This broader view of evolutionary change highlights the importance of considering mechanisms that fall outside of traditional, gradualist models.<\/p>\n<\/div>\n<h2 class=\"import-Normal\">The Biopolitics of Heredity<\/h2>\n<p class=\"import-Normal\">\u201cScience isn\u2019t political\u201d is a sentiment that you have likely heard before. Science is supposed to be about facts and objectivity. It exists, or at least ought to, outside of petty human concerns. However, the sorts of questions we ask as scientists, the problems we choose to study, the categories and concepts we use, who gets to do science, and whose work gets cited are all shaped by culture. Doing science is a political act. This fact is markedly true for human evolution. While it is easier to create intellectual distance between us and fruit flies and viruses, there is no distance when we are studying ourselves. The hardest lesson to learn about human evolution is that it is intensely political. Indeed, to see it from the opposite side, as it were, the history of creationism\u2014the belief that the universe was divinely created around 6,000 years ago\u2014is essentially a history of legal decisions. For instance, in <em>Tennessee v. John T. Scopes<\/em> (1925), a schoolteacher was prosecuted for violating a law in Tennessee that prohibited the teaching of human evolution in public schools, where teachers were required by law to teach creationism.<\/p>\n<p class=\"import-Normal\">More recently, legal decisions aimed at legislating science education have shaped how students are exposed to evolutionary theory. For instance, <em>McLean v. Arkansas<\/em> (1982) dispatched \u201cscientific creationism\u201d by arguing that the imposition of balanced teaching of evolution and creationism in science classes violates the Establishment Clause, separating church and state. Additionally, <em>Kitzmiller v. Dover (Pennsylvania) Area School District<\/em> (2005) dispatched the teaching of \u201cintelligent design\u201d in public school classrooms as it was deemed to not be science. In some cases, people see unbiblical things in evolution, although most Christian theologians are easily able to reconcile science to the Bible. In other cases, people see immoral things in evolution, although there is morality and immorality everywhere. And some people see evolution as an aspect of alt-religion, usurping the authority of science in schools to teach the rejection of the Christian faith, which would be unconstitutional due to the protected separation of church and state.<\/p>\n<p class=\"import-Normal\">Clearly, the position that politics has nothing to do with science is untenable. But is the politics in evolution an aberration or is it somehow embedded in science? In the early 20th century, scientists commonly promoted the view that science and politics were separate: science was seen as a pure activity, only rarely corrupted by politics. And yet as early as World War I, the politics of nationalism made a hero of the German chemist Fritz Haber for inventing poison gas. And during World War II, both German doctors and American physicists, recruited to the war effort, helped to end many civilian lives. Therefore, we can think of the apolitical scientist as a self-serving myth that functions to absolve scientists of responsibility for their politics. The history of science shows how every generation of scientists has used evolutionary theory to rationalize political and moral positions. In the very first generation of evolutionary science, Darwin\u2019s <em>Origin of Species<\/em> (1859) is today far more readable than his <em>Descent of Man<\/em> (1871). The reason is that Darwin consciously purged <em>The Origin of Species<\/em> of any discussion of people. And when he finally got around to talking about people, in <em>The Descent of Man<\/em>, he simply imbued them with the quaint Victorian prejudices of his age, and the result makes you cringe every few pages. There is plenty of politics in there\u2014sexism, racism, and colonialism\u2014because <em>you cannot talk about people apolitically<\/em>.<\/p>\n<p class=\"import-Normal\">One immediate faddish deduction from Darwinism, popularized by Herbert Spencer (1864) as \u201csurvival of the fittest,\u201d held that unfettered competition led to advancement in nature and to human history. Since the poor were purported losers in that struggle, anything that made their lives easier would go against the natural order. This position later came to be known ironically as \u201cSocial Darwinism.\u201d Spencer was challenged by fellow Darwinian Thomas Huxley (1863), who agreed that struggle was the law of the jungle but observed that we don\u2019t live in jungles anymore. The obligation to make lives better for others is a moral, not a natural, fact. We simultaneously inhabit a natural universe of descent from apes and a moral universe of injustice and inequality, and science is not well served by ignoring the latter.<\/p>\n<p class=\"import-Normal\">Concurrently, the German biologist Ernst Haeckel\u2019s 1868 popularization of Darwinism was translated into English a few years later as <em>The History of Creation<\/em>. As we saw earlier, Haeckel was determined to convince his readers that they were descended from apes, even in the absence of fossil evidence attesting to it. When he made non-Europeans into the missing links that connected his readers to the apes, and depicted them as ugly caricatures, he knew precisely what he was doing. Indeed, even when the degrading racial drawings were deleted from the English translation of his book, the text nevertheless made his arguments quite clear. And a generation later, when the Americans had not yet entered the Great War in 1916, a biologist named Vernon Kellogg visited the German High Command as a neutral observer and found that the officers knew a lot about evolutionary biology, which they had gotten from Haeckel and which rationalized their military aggressions. Kellogg went home and wrote a bestseller about it, called <em>Headquarters Nights<\/em> (1917). World War I would have been fought with or without evolutionary theory, but as a source of scientific authority, evolution\u2014even if a perversion of the Darwinian theory\u2014had very quickly attained global geopolitical relevance.<\/p>\n<p class=\"import-Normal\">Oftentimes, politics in evolutionary science is subtle, due to the pervasive belief in the advancement of science. We recognize the biases of our academic ancestors and modify our scientific stories accordingly. But we can never be free of our own cultural biases, which are invisible to us, as much as our predecessors\u2019 biases were invisible to them. In some cases, the most important cultural issues resurface in different guises each generation, like scientific racism. <strong>Scientific racism<\/strong> is the recruitment of science for the evil political ends of racism, and it has proved remarkably impervious to evolution. Before Darwin, there was creationist scientific racism, and after Darwin, there was evolutionist scientific racism. And there is still scientific racism today, self-justified by recourse to evolution, which means that scientists have to be politically astute and sensitive to the uses of their work to counter these social tendencies.<\/p>\n<p class=\"import-Normal\">Consider this: Are you just your ancestry, or can you transcend it? If that sounds like a weird question, it was actually quite important to a turn-of-the-20th-century European society in which an old hereditary aristocracy was under increasing threat from a rising middle class. And that is why the very first English textbook of Mendelian genetics concluded with the thought that \u201cpermanent progress is a question of breeding rather than of pedagogics; a matter of gametes, not of training \u2026 the creature is not made but born\u201d (Punnett 1905, 60). <em>Translation: Not only do we now know a bit about how heredity works, but it\u2019s also the most important thing about you. Trust me, I\u2019m a scientist.<\/em><\/p>\n<p class=\"import-Normal\">Yet evolution is about how descendants come to differ from ancestors. Do we really know that your heredity, your DNA, your ancestry, is the most important thing about you? That you were born, not made? After all, we do know that you could be born into slavery or as a peasant, and come from a long line of enslaved people or peasants, and yet not have slavery or peasantry be the most important thing about you. Whatever your ancestors were may unfortunately constrain what you can become, but as a moral precept, it should not. But just as science is not purely \u201cfacts and objectivity,\u201d ancestry is not a strictly biological concept. Human ancestry is biopolitics, not biology.<\/p>\n<p class=\"import-Normal\">Evolution is fundamentally a theory about ancestry, and yet ancestors are, in the broad anthropological sense, sacred: ancestors are often more meaningful symbolically than biologically. Just a few years after <em>The Origin of Species <\/em>(Darwin 1859), the British politician and writer Benjamin Disraeli declared himself to be on the side of the angels, not the apes, and to \u201crepudiate with indignation and abhorrence those new-fangled theories\u201d (Monypenny, Flavelle, and Buckle 1920, 105). He turned his back on an ape ancestry and looked to the angel; yet, he did so as a prominent Jew-turned-Anglican, who had personally transcended his humble roots and risen to the pinnacle of the Empire. Ancestry was certainly important, and Disraeli was famously proud of his, but it was also certainly not the most important thing, not the primary determinant of his place in the world. Indeed, quite the opposite: Disraeli\u2019s life was built on the transcendence of many centuries of Jewish poverty and oppression in Europe. Humble ancestry was there to be superseded and nobility was there to be earned; Disraeli would later become the Earl of Beaconsfield. Clearly, \u201care you just your ancestry\u201d is not a value-neutral question, and \u201cthe creature is not made, but born\u201d is not a value-neutral answer.<\/p>\n<p class=\"import-Normal\">Ancestry being the most important thing about a person became a popular idea twice in 20th century science. First, at the beginning of the century, when the <strong>eugenics<\/strong> movement in America called attention to \u201cfeeble-minded stocks,\u201d which usually referred to the poor or to immigrants (see Figure 3.4). This movement culminated in Congress restricting the immigration of \u201cfeeble-minded races\u201d (said to include Jews and Italians) in 1924, and the Supreme Court declaring it acceptable for states to sterilize their \u201cfeeble-minded\u201d citizens involuntarily in 1927. After the Nazis picked up and embellished these ideas during World War II, Americans moved swiftly away from them in some contexts (e.g., for most people of European descent) while still strictly adhering in other contexts such as Japanese internment camps and immigration restrictions.<\/p>\n<figure style=\"width: 374px\" class=\"wp-caption alignright\"><img class=\"\" src=\"https:\/\/opentextbooks.concordia.ca\/explorations\/wp-content\/uploads\/sites\/57\/2023\/08\/image4-6.png\" alt=\"Historic photo. People sit in front of a structure with a \u201cEugenic and Health Exhibit&quot; banner.\" width=\"374\" height=\"262\" \/><figcaption class=\"wp-caption-text\">Figure 3.4: Eugenic and Health Exhibit, Fitter Families exhibit, and examination building, Kansas State Free Fair. Credit: <a href=\"https:\/\/www.dnalc.org\/view\/16328-Gallery-14-Eugenics-Exhibit-at-the-Kansas-State-Free-Fair-1920.html\" target=\"_blank\">Gallery 14: Eugenics Exhibit at the Kansas State Free Fair, 1920 ID (ID 16328)<\/a> by <a href=\"https:\/\/www.dnalc.org\/\" target=\"_blank\">Cold Spring Harbor<\/a> (Courtesy American Philosophical Society) is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-nd\/3.0\/us\/\" target=\"_blank\">CC BY-NC-ND 3.0 License.<\/a><\/figcaption><\/figure>\n<p class=\"import-Normal\">Ancestry again became paramount in the drumming up of public support for the Human Genome Project in the 1990s. Public support for sequencing the human genome was encouraged by a popular science campaign that featured books titled <em>The Book of Man <\/em>(Bodmer &amp; McKie 1997), <em>The Human Blueprint <\/em>(Shapiro 1991), and <em>The Code of Codes<\/em> (Kevles &amp; Hood 1993). These books generally promised cures for genetic diseases and a deeper understanding of the human condition. We can certainly identify progress in molecular genetics over the last couple of decades since the human genome was sequenced, but that progress has notably not been accompanied by cures for genetic diseases, nor by deeper understandings of the human condition.<\/p>\n<p class=\"import-Normal\">Even at the most detailed and refined levels of genetic analysis, we still don\u2019t have much of an understanding of the actual basis by which things seem to \u201crun in families.\u201d While the genetic basis of simple, if tragic, genetic diseases have become well-known\u2014such as sickle-cell anemia, cystic fibrosis, and Tay-Sachs\u2019 Disease\u2014we still haven\u2019t found the ostensible genetic basis for traits that are thought to have a strong genetic component. For example, a recent genetic summary found over 12,000 genetic sites that contributed to height yet still explained only about 40-50 percent of the variation in height among European ancestry but no more than 10-20 percent of variation of other ancestries, which we know strongly runs in families (Yengo Et al. 2022).<\/p>\n<p class=\"import-Normal\">Partly in reaction to the reductionistic hype of the Human Genome Project, the study of epigenetics has become the subject of great interest. One famous natural experiment involves a Nazi-imposed famine in Holland over the winter of 1944\u20131945. Children born during and shortly after the famine experienced a higher incidence of certain health problems as adults, many decades later. Apparently, certain genes had been down-regulated early in development and remained that way throughout the course of life. Indeed, this modified regulation of the genes in response to the severe environmental conditions may have been passed on to their children.<\/p>\n<p class=\"import-Normal\">Obviously one\u2019s particular genetic constitution may play an important role in one\u2019s life trajectory. But overvaluing that role may have important social and political consequences. In the first place, genotypes are rendered meaningful in a cultural universe. Thus, if you live in a strongly patriarchal society and are born without a Y chromosome (since human males are chromosomally XY and females XX), your genotype will indeed have a strong effect upon your life course. So even though the variation is natural, the consequences are political. The mediating factors are the cultural ideas about how people of different sexes ought to be treated, and the role of the state in permitting certain people to develop and thrive. More broadly, there are implications for public education if variation in intelligence is genetic. There are implications for the legal system if criminality is genetic. There are implications for the justice system if sexual preference, or sexual identity, is genetic. There are implications for the development of sports talent if that is genetic. And yet, even for the human traits that are more straightforward to measure and known to be strongly heritable, the DNA base sequence variation seems to explain little.<\/p>\n<p class=\"import-Normal\">Genetic determinism or <strong>hereditarianism<\/strong> is the idea that \u201cthe creature is made, not born\u201d\u2014or, in a more recent formulation by James Watson, that \u201cour fate is in our genes.\u201d One of the major implications drawn from genetic determinism is that the feature in question must inevitably express itself; therefore, we can\u2019t do anything about it. Therefore, we might as well not fund the social programs designed to ameliorate economic inequality and improve people\u2019s lives, because their courses are fated genetically. And therefore, they don\u2019t deserve better lives.<\/p>\n<p class=\"import-Normal\">All of the \u201ctherefores\u201d in the preceding paragraph are open to debate. What is important is that the argument relies on a very narrow understanding of the role of genetics in human life, and it misdirects the causes of inequality from cultural to natural processes. By contrast, instead of focusing on genes and imagining them to place an invisible limit upon social progress, we can study the ways in which your DNA sequence does <em>not<\/em> limit your capability for self-improvement or fix your place in a social hierarchy. In general, two such avenues exist. First, we can examine the ways in which the human body responds and reacts to environmental variation: human adaptability and plasticity. This line of research began with the anthropometric studies of immigrants by Franz Boas in the early 20th century and has now expanded to incorporate the epigenetic inheritance of modified human DNA. And second, we can consider how human lives are shaped by social histories\u2014especially the structural inequalities within the societies in which they grow up.<\/p>\n<p class=\"import-Normal\">Although it arises and is refuted every generation, the radical hereditarian position (genetic determinism) perennially claims to speak for both science and evolution. It does not. It is the voice of a radical fringe\u2014perhaps naive, perhaps evil. It is not the authentic voice of science or of evolution. Indeed, keeping Charles Darwin\u2019s name unsullied by protecting it from association with bad science often seems like a full-time job. Culture and epigenetics are very much a part of the human condition, and their roles are significant parts of the complete story of human evolution.<\/p>\n<div class=\"textbox\" style=\"background: var(--lightblue)\">\n<h2><strong>Special Topic: Oversexing the Gendered Body <\/strong><\/h2>\n<p>While rapid mitochondrial evolution underscores the biological flexibility of organisms in response to environmental pressures, evolutionary theory is also shaped by another set of forces: cultural assumptions and social norms. Nowhere is this more visible than in scientific interpretations of sex and gender. Many modern gender roles stem from assumptions about sex differences that have accumulated throughout human history. While these roles may appear to be fixed stereotypes or biologically predetermined, they can be deconstructed by examining the processes of sexual selection through queer and feminist theoretical frameworks. Applying these lenses to evolutionary concepts allows for a deeper understanding of how cultural ideologies, particularly those surrounding gender and sexuality, shape interpretations of biological processes.<\/p>\n<p>Darwin first introduced the concept of sexual selection in The Descent of Man (1871) to explain how males and females may have developed different traits that would be detrimental to the species\u2019 overall survival <a href=\"https:\/\/www.zotero.org\/google-docs\/?GVyarx\" target=\"_blank\">(Vicedo, 2025)<\/a>. Unlike natural selection which is \u201cselection by death,\u201d sexual selection represents death by selection <a href=\"https:\/\/www.zotero.org\/google-docs\/?G5vjwZ\" target=\"_blank\">(Gayon, 2010)<\/a>. Darwin argued that males typically compete intrasexually for female attention, and that females exercise choice based on attractiveness or vigor, proving their fitness. However, when reframed through feminist theory, the amount of agency Darwin ascribed to females doesn\u2019t reflect the societal assumptions surrounding gender roles in his era. Charlotte Perkins Gilman in her publication Women and Economics, argued that by the 1960s, men increasingly relied on social dominance over women rather than competition with other men (Vicedo, 2025). This dynamic required women to continually enhance their sexual appeal in exchange for economic security, a system she coined the \u201csexuo-economic relationship\u201d (2025, p.5). This framework reveals the societal power imbalance between men and women, and how women are the ones sexualizing themselves and competing for partners, not men. Such processes would lead to the modern oversexualization of women.<\/p>\n<p>Oversexualization, a cultural ideology that prioritizes sexual appeal over autonomy and well-being, further complicates interpretations of sexual selection. Brassard and company (2018) define oversexualization through four components: valuing people solely for their sexual appeal, societal norms of equating attractiveness with sexiness, sexual objectification, and the inappropriate imposition of sexuality (Brassard Et al., 2018, p.16-17). When oversexualization is observed within a population, it may signal that the pressures of sexual selection have intensified relative to that of natural selection, creating \u201cexcessive sex difference\" (Vicedo,<a href=\"https:\/\/www.zotero.org\/google-docs\/?a1BV2F\" target=\"_blank\"> 2025)<\/a>. While many aspects of Gilman's arguments do not directly apply to contemporary gender dynamics, stereotypes rooted in historical gender expectations continue to shape women's experiences in the workforce and broader society (2025). Understanding sexual selection as a culturally mediated process, rather than as a simple competition amongst males, offers a more nuanced picture of how gender ideologies influence biological narratives. This intersection of culture and biology is crucial for studying gender roles, queer relationships, and sexual diversity across societies and time periods.<\/p>\n<\/div>\n<p>&nbsp;<\/p>\n<div class=\"__UNKNOWN__\">\n<h2 class=\"import-Normal\">Adaptationism and the Panglossian Paradigm<\/h2>\n<p class=\"import-Normal\">The story of human evolution, and the evolution of all life for that matter, is never settled because evolution is ongoing. Additionally, because the conditions that shape evolutionary trajectories are not predetermined, evolution itself is emergent. Even during periods of ecological stability, when fewer macroevolutionary changes occur, populations of organisms continue to experience change. When ecological stability is disrupted, populations must adapt to the changes. Darwin explained in naturalistic terms how animals adapt to their environments: traits that contribute to an organism's ability to survive and reproduce in specific environments will become more common. The most \u201cfit\u201d\u2014those organisms best suite<\/p>\n<figure style=\"width: 279px\" class=\"wp-caption alignright\"><img class=\"\" src=\"https:\/\/opentextbooks.concordia.ca\/explorations\/wp-content\/uploads\/sites\/57\/2023\/08\/image3-5.png\" alt=\"Human hand is smaller with smaller fingers and smoother skin compared to a chimpanzee hand.\" width=\"279\" height=\"264\" \/><figcaption class=\"wp-caption-text\">Figure 3.5: Drawings of a human hand (left) and a chimpanzee hand (right). Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__\/\" target=\"_blank\">Human and chimpanzee hand (Figure 2.16)<\/a> by Mary Nelson original to <a href=\"https:\/\/explorations.americananthro.org\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">d to the <em>current<\/em> environmental conditions in which they live\u2014have survived over eons of the history of life on earth to cocreate ecosystems full of animals and plants. Our own bodies are full of evident adaptations: eyes for seeing, ears for hearing, feet for walking on, and so forth.<\/p>\n<p class=\"import-Normal\">But what about hands? Feet are adapted to be primarily weight-bearing structures (rather than grasping structures, as in the apes) and that is what we primarily use them for. But we use our hands in many ways: for fine-scale manipulation, greeting, pointing, stimulating a sexual partner, writing, throwing, and cooking, among other uses. So which of these uses express what hands are \u201cfor,\u201d when all of them express what hands do?<\/p>\n<p class=\"import-Normal\">Gould and Lewontin (1979) illustrate the problem with assuming that the function of a trait defines its evolutionary cause. Consid<\/p>\n<p class=\"import-Normal\">er the case of Dr. Pangloss\u2014the protagonistic of Voltaire\u2019s <em>Candide<\/em>\u2014who believed that we lived in the best of all possible worlds. Gould and Lewontin use his pronouncement that \u201cnoses were made for spectacles and so we have spectacles\u201d to demonstrate the problem with assuming any trait has evolved for a specific purpose. Identifying a function of a trait does not necessitate that the function is the ultimate cause of the trait. Individual traits are not under selection pressures in isolation; in fact, an entire organism must be able to survive and reproduce in their environment. When natural selection results in adaptations, changes that occur in some traits can have cascading effects throughout the phenotype and features that are not under selection pressure can also change.<\/p>\n<p>&nbsp;<\/p>\n<div class=\"textbox\" style=\"background: var(--lightblue)\">\n<h2>Dig Deeper: Rapid Mitochondrial Evolution in Stingless Bees<\/h2>\n<p>A striking example of this interactional evolutionary change comes from recent research on stingless bees. When observing the mitochondrial genome (mitogenome) in two Australian stringless bees in the genus Tetragonula\u2014T. carbonaria and T. hockingsi\u2014they exhibit a rare\u00a0 duplication of the entire mitogenome and show rapid divergence from other members of their species <a href=\"https:\/\/www.zotero.org\/google-docs\/?yfSvM1\" target=\"_blank\">(Fran\u00e7oso et al., 2023)<\/a>. This accelerated evolution is hypothesized to result from factors such as low effective population, founder effects, and genome duplication triggered by environmental stressors. This phenomenon echoes the earlier work by Conrad H. Waddington (1956) mentioned in this chapter, whose experiments exposing fruit fly embryos to ether induced the development of additional wings and thoraces, changes that later became heritable under stable conditions <a href=\"https:\/\/www.zotero.org\/google-docs\/?FdVXeR\" target=\"_blank\">(Shook et al., 2023b)<\/a>. Both cases highlight how organisms can respond to intense environmental pressures through dramatic developmental and genetic shifts.<\/p>\n<p>The mitochondria genetics influence the energy synthesis of the cells and in most animals, the mitogenome remains relatively stable <a href=\"https:\/\/www.zotero.org\/google-docs\/?Lw5Lmk\" target=\"_blank\">(Shook et al., 2023a)<\/a>; however, Tetragonula species appear to possess an unusual capacity for rapid sequence rearrangement and complete genome duplication, suggesting that their mitogenomes play an important adaptive role. Comparing these genomes with other species such as Lepidotrigona\u2014which shows rearrangements but no duplication\u2014 provides a unique opportunity to examine how different lineages respond to similar ecological pressures. <a href=\"https:\/\/www.zotero.org\/google-docs\/?VxrGpj\" target=\"_blank\">Fran\u00e7oso et al. (2023)<\/a> found that Tetragonula mitogenomes form amphimeric circular structures in which two complete genomes are joined head-to-tail, an extremely rare configuration. These arrangements, including inversions and translocations of gene blocks such as ND6, CytB, ND1, and several rRNA and tRNA genes, are far less common in other bee genera. This pattern supports the idea proposed by <a href=\"https:\/\/www.zotero.org\/google-docs\/?V2eJWI\" target=\"_blank\">Gould &amp; Eldredge (1977)<\/a> that species are fundamentally unstable entities subject to bursts of rapid change in response to environmental pressures, rather than progressing along a single linear pathway. It is important to note that not all species within the genus exhibit the same degree or type of genomic flexibility. While T. carbonaria and T. hockingsi show full mitogenome duplications, the aforementioned Lepidotrigona species show only partial rearrangements despite facing similar environmental conditions. This variation challenges deterministic assumptions that evolution necessarily moves species toward optimal forms. Instead, it illustrates that evolution often involves trial-and-error shifts shaped by constraint, chance, and ecological stress.<\/p>\n<p>Although further research is needed to determine precisely what triggers such rapid genomic events, the evidence demonstrates that mitochondria play an active role in shaping evolutionary pathways. These findings complicate traditional gradualist models and highlight the importance of examining molecular responses to environmental pressures.<\/p>\n<\/div>\n<p>&nbsp;<\/p>\n<p class=\"import-Normal\">There is an important lesson in recognizing that what things do in the present is not a good guide to understanding why they came to exist. Gunpowder was invented for entertainment\u2014only later was it adopted for killing people. The Internet was invented to decentralize computers in case of a nuclear attack\u2014and only later adopted for social media. Apes have short thumbs and use their hands in locomotion; our ancestors stopped using their hands in locomotion by about six million years ago and had fairly modern-looking hands by about two million years ago. We can speculate that a combination of selection for abstract thought and dexterity led to evolution of the human hand, with its capability for toolmaking that exceeds what apes can do (see Figure 3.5). But let\u2019s face it\u2014how many tools have you made today?<\/p>\n<p class=\"import-Normal\">Consequently, we are obliged to see the human foot as having a purpose to which it is adapted and the human hand as having multiple purposes, most of which are different from what it originally evolved for. Paleontologists Gould and Elisabeth Vrba suggested that an original use be regarded as an adaptation and any additional uses be called \u201c<strong>exaptations.<\/strong>\u201d Thus, we would consider the human hand to be an adaptation for toolmaking and an exaptation for writing. So how do we know whether any particular feature is an adaptation, like the walking foot, rather than an exaptation, like the writing hand? Or more broadly, how can we reason rigorously from what a feature does to what it evolved for?<\/p>\n<p class=\"import-Normal\">The answer to the question \u201cwhat did this feature evolve for?\u201d creates an origin myth. This origin myth contains three assumptions: (1) features can be isolated as evolutionary units; (2) there is a specific reason for the existence of any particular feature; and (3) there is a clear and simplistic explanation for why the feature evolved.<\/p>\n<figure style=\"width: 378px\" class=\"wp-caption alignright\"><img src=\"https:\/\/opentextbooks.concordia.ca\/explorations\/wp-content\/uploads\/sites\/57\/2023\/08\/image9-8.png\" alt=\"Head with images and human qualities drawn on it. Journal title printed at the bottom.\" width=\"378\" height=\"437\" \/><figcaption class=\"wp-caption-text\">Figure 3.6: According to the early 19th century science of phrenology, units of personality could be mapped onto units in the head, as shown on this cover of The Phrenology Journal. Credit: <a href=\"https:\/\/wellcomecollection.org\/works\/b6skynug\" target=\"_blank\">Phrenology; Chart<\/a> [slide number 5278, photo number: L0000992, original print from Dr. E. Clark, The Phrenological Journal (Know Thyself)] by <a href=\"https:\/\/wellcomecollection.org\/\" target=\"_blank\">Wellcome Collection<\/a>, is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/legalcode\" target=\"_blank\">CC BY 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">The first assumption was appreciated a century ago as the \u201cunit-character problem.\u201d Are the units by which the body grows and evolves the same as units we name? This is clearly not the case: we have genes and we have noses, and we have genes that affect noses, but we don\u2019t have \u201cnose genes.\u201d What is the relationship between the evolving elements that we see, identify, and name, and the elements that biologically exist and evolve? It is hard to know, but we can use the history of science as a guide to see how that fallacy has been used by earlier generations. Back in the 19th century, the early anatomists argued that since the brain contained the mind, they could map different mental states (acquisitiveness, punctuality, sensitivity) onto parts of the brain. Someone who was very introspective, say, would have an enlarged introspection part of the brain, a cranial bulge to represent the hyperactivity of this mental state. The anatomical science was known as <strong>phrenology<\/strong>, and it was predicated on the false assumption that units of thought or personality or behaviour could be mapped to distinct parts of the brain and physically observed (see Figure 3.6). This is the fallacy of reification, imagining that something named is something real.<\/p>\n<figure style=\"width: 295px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"https:\/\/opentextbooks.concordia.ca\/explorations\/wp-content\/uploads\/sites\/57\/2023\/08\/image1-8-1.png\" alt=\"A black-and-white drawing of a chimpanzee head and face.\" width=\"295\" height=\"236\" \/><figcaption class=\"wp-caption-text\">Figure 3.7: Chimpanzees have big ears. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Chimpanzee_head_sketch.png\" target=\"_blank\">Chimpanzee head sketch<\/a> by <a href=\"https:\/\/de.wikipedia.org\/wiki\/Benutzer:Roger_Zenner\" target=\"_blank\">Roger Zenner<\/a>, original by Brehms Tierleben (1887), is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\" target=\"_blank\">public domain<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">The second assumption, that everything has a reason, has long been recognized as a core belief of religion. Our desire to impose order and simplicity on the workings of the universe, however, does not constrain it to obey simple and orderly causes. Magic, witchcraft, spirits, and divine agency are all powerful explanations for why things happen. Consequently, it is probably not a good idea to lump natural selection in with those. Sometimes things do happen for a reason, of course, but other times things happen as byproducts of other things, or for very complicated and entangled reasons, or for no reason at all. What phenomena have reasons and thereby merit explanation? Chimpanzees have very large testicles, and we think we know why: their promiscuous sexual behaviour triggers intense competition for high sperm count. But chimpanzees also have very large ears, but much less scientific attention has been paid to this trait (see Figure 3.7). Why not? Why should there be a reason for chimp testicles but not for chimp ears? What determines the kinds of features that we try to explain, as opposed to the ones that we do not? Again, the assumption that any specific feature has a reason is metaphysical; that is to say, it may be true in any particular case, but to assume it in all cases is gratuitous.<\/p>\n<p class=\"import-Normal\">And third, the possibility of knowing what the reason for any particular feature is, assuming that it has one, is a challenge for evolutionary epistemology (the theory of how we know things). Consider the big adaptations of our lineage: bipedalism and language. Nobody doubts that they are good, and they evolved by natural selection, and we know how they work. But why did they evolve? If talking and walking are simply better than not talking and not walking, then why did they evolve in just a single branch of the ape lineage in the primate family tree? We don\u2019t know what bipedalism evolved for, although there are plenty of speculations: walking long distances, running long distances, cooling the head, seeing over tall grass, carrying babies, carrying food, wading, threatening, counting calories, sexual display, and so on. Neither do we know what language evolved for, although there are speculations: coordinating hunting, gossiping, manipulating others. But it is also possible that bipedality is simply the way that a small arboreal ape travels on the ground, if it isn\u2019t in the treetops. Or that language is simply the way that a primate with small canine teeth and certain mental propensities comes to communicate. If that were true, then there might be no reason for bipedality or language: having the unique suite of preconditions and a fortuitous set of circumstances simply set them in motion, and natural selection elaborated and explored their potentials. It is possible that walking and talking simply solved problems that no other lineage had ever solved; but even if so, the fact remains that the rest of the species in the history of life have done pretty well without having solved them.<\/p>\n<p class=\"import-Normal\">It is certainly very optimistic to think that all three assumptions (that organisms can be meaningfully atomized, that everything has a reason, and that we can know the reason) would be simultaneously in effect. Indeed, just as there are many ways of adapting (genetically, epigenetically, behaviourally, culturally), there are also many ways of being nonadaptive, which would imply that there is no reason at all for the feature in question.<\/p>\n<p class=\"import-Normal\">First, there is the element of randomness of population histories. There are more cases of sickle-cell anemia among sub-Saharan Africans than other peoples, and there is a reason for it: carriers of sickle-cell anemia have a resistance to malaria, which is more frequent in parts of Africa (as discussed in Chapters 4 and 14). But there are more cases of a blood disease called variegated porphyria, a rare genetic metabolic disorder, in the Afrikaners of South Africa (descendants of mostly Dutch settlers in the 17th century) than in other peoples, and there is no reason for it. Yet we know the cause: One of the founding Dutch colonial settlers had the <strong>allele<\/strong>\u2013a variant of a gene\u2013and everyone in South Africa with it today is her descendant. But that is not a reason\u2014that is simply an accident of history.<\/p>\n<p class=\"import-Normal\">Second, there is the potential mismatch between the past and the present. The value of a particular feature in the past may be changed as the environmental circumstances change. Our species is diurnal, and our ancestors were diurnal. But beginning around a few hundred thousand years ago, our ancestors could build fires, which extended the light period, which was subsequently further amplified by lamps and candles. And over the course of the 20th century, electrical power has made it possible for people to stay up very late when it is dark\u2014working, partying, worrying\u2014to a greater extent than any other closely related species. In other words, we evolved to be diurnal, yet we are now far more nocturnal than any of our recent ancestors or close relatives. Are we adapting to nocturnality? If so, why? Does it even make any sense to speak of the human occupation of a nocturnal ape niche, despite the fact that we empirically seem to be doing just that? And if so, does it make sense to ask what the reason for it is?<\/p>\n<p class=\"import-Normal\">Third, there is a genetic phenomenon known as a selective sweep, or the hitchhiker effect. Imagine three genes\u2014A, B, and C\u2014located very closely together on a chromosome. They each have several variants, or alleles, in the population. Now, for whatever reason, it becomes beneficial to have one of the B alleles, say B4; this B4 allele is now under strong positive selection. Obviously, we will expect future generations to be characterized by mostly B4. But what was B4 attached to? Because whatever A and C alleles were adjacent to it will also be quickly spread, simply by virtue of the selection for B4. Even if the A and C alleles are not very good, they will spread because of the good B4 allele between them. Eventually the linkage groups will break up because of genetic crossing-over in future generations. But in the meantime, some random version of genes A and C are proliferating in the species simply because they are joined to superior allele B4. And clearly, the A and C alleles are there because of selection\u2014but not because of selection <em>for<\/em> them!<\/p>\n<p class=\"import-Normal\">Fourth, some features are simply consequences of other properties rather than adaptations to external conditions. We already noted the phenomenon of allometric growth, in which some physical features have to outgrow others to maintain function at an increased size. Can we ask the reason for the massive brow ridges of <em>Homo erectus<\/em>, or are brow ridges simply what you get when you have a conjunction of thick skull bones, a large face, and a sloping forehead\u2014and, thus, again would have a cause but no reason?<\/p>\n<p class=\"import-Normal\">Fifth, some features may be underutilized and on the way out. What is the reason for our two outer toes? They aren\u2019t propulsive, they don\u2019t do anything, and sometimes they\u2019re just in the way. Obviously they are there because we are descended from ancestors with five digits on their hands and feet. Is it possible that a million years from now, we will just have our three largest toes, just as the ancestors of the horse lost their digits in favour of a single hoof per limb? Or will our outer toes find another use, such as stabilizing the landings in our personal jet-packs? For the time being, we can just recognize vestigiality as another nonadaptive explanation for the presence of a given feature.<\/p>\n<p class=\"import-Normal\">Finally, Darwin himself recognized that many obvious features do not help an animal survive. Some things may instead help an animal breed. The peacock\u2019s tail feathers do not help it eat, but they do help it mate. There is competition, but only against half of the species. Darwin called this <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1084\">sexual selection<\/a><\/strong>. Its result is not a fit to the environment but, rather, a fit to the opposite sex. In some species, that is literally the case, as the male and female genitalia have specific ways of anatomically fitting together. The specific form is less important than the specific match, so inquiring about the reason for a particular form of the reproductive anatomy may be misleading. The specific form may be effectively random, as long as it fits the opposite sex and is different from the anatomies of other species. Nor is sexual selection the only form of selection that can affect the body differently from natural selection. Competition might also take place between biological units other than organisms\u2014perhaps genes, perhaps cells, or populations, or species. The spread of cultural things, such as head-binding or cheap refined fructose or forced labour, can have significant effects upon bodies, which are also not adaptations produced by natural selection. They are often adaptive physiological responses to stresses but not the products of natural selection.<\/p>\n<p class=\"import-Normal\">With so many paths available by which a physical feature might have organically arisen without having been the object of natural selection, it is unwise to assume that any individual trait is an adaptation. And that generalization applies to the best-known, best-studied, and most materially based evolutionary adaptations of our lineage. But our cultural behaviours are also highly adaptive, so what about our most familiar social behaviours? Patriarchy, hierarchy, warfare\u2014are these adaptations? Do they have reasons? Are they good for something?<\/p>\n<p class=\"import-Normal\">This is where some sloppy thinking has been troublesome. What would it mean to say that patriarchy evolved by natural selection in the human species? If, on the one hand, it means that the human mind evolved by natural selection to be able to create and survive in many different kinds of social and political regimes, of which patriarchy is one, then biological anthropologists will readily agree. If, on the other hand, it means that patriarchy evolved by natural selection, that implies that patriarchy is genetically determined (since natural selection is a genetic process) and out-reproduced the alleles for other, more egalitarian, social forms. This in turn would imply that patriarchy is an adaptation and therefore of some beneficial value in the past and has become an ingrained part of human nature today. This would be bad news, say, if you harboured ambitions of dismantling it. Dismantling patriarchy in that case would be to go against nature, a futile gesture. In other words, this latter interpretation would be a naturalistic manifesto for a conservative political platform: don\u2019t try to dismantle the patriarchy, because it is within us, the product of evolution\u2014suck it up and live with it.<\/p>\n<p class=\"import-Normal\">Here, evolution is being used as a political instrument for transforming the human genome into an imaginary glass ceiling against equality. There is thus a convergence between the pseudo-biology of crude <strong>adaptationism <\/strong>(the idea that everything is the product of natural selection) and the pseudo-biology of hereditarianism. Naturalizing inequality is not the business of evolutionary theory, and it represents a difficult moral position for a scientist to adopt, as well as a poor scientific position.<\/p>\n<div class=\"textbox\" style=\"background: var(--lightblue)\">\n<p class=\"import-Normal\"><strong style=\"font-family: &#039;Cormorant Garamond&#039;, serif;font-size: 1.602em\">Evolution of the Anthropocene <\/strong><\/p>\n<figure style=\"width: 379px\" class=\"wp-caption alignright\"><img class=\"\" src=\"https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/8\/8f\/Absetzterseite_des_Tagebaus_Inden_2002.jpg\/500px-Absetzterseite_des_Tagebaus_Inden_2002.jpg\" alt=\"File:Absetzterseite des Tagebaus Inden 2002.jpg\" width=\"379\" height=\"200\" \/><figcaption class=\"wp-caption-text\">Figure 3.8: View of the overburden dumping side of the Inden open-pit lignite mine in the Rhineland, Germany, showing layers of excavated earth used to reconstruct the landscape. Credit: <em data-start=\"249\" data-end=\"289\">Absetzterseite des Tagebaus Inden 2002<\/em> by Rhetos is dedicated to the public domain under the <a href=\"https:\/\/creativecommons.org\/publicdomain\/zero\/1.0\/deed.en\">Creative Commons CC0 1.0 Universal Public Domain Dedication. <\/a><\/figcaption><\/figure>\n<p>Under the previously explored Adaptationism and Panglossian Paradigm, it is explained that human evolution is constantly occurring even throughout periods of ecological stability. While this acknowledges evolution as an ongoing process of change, it fails to explore the implications of such on the alteration of other species and ecosystems.<\/p>\n<p>The emergence of the Anthropocene, driven by human activity, though not recognized as an official epoch, is seen as a transformative event comparable to other major historical shifts such as the Ordovician Biodiversification (UNESCO, 2024). Given its scale, it is crucial to inform scholars about the impact of our social and cultural evolution on the rest of the world. Richard Robbins\u2019 Global Problems and Culture of Capitalism explains how the modern culture of consumption has been extremely successful at accommodating populations of people far larger than previously possible. Robbins claims that the globalization attributed to capitalism has allowed the world to make full use of its environmental resources, providing necessities and innovative technologies to humans all over the world (Robbins &amp; Dowty, 2019). In other words, capitalism is an anthropocentric cultural system that highly benefits humans and facilitates our survival with little regard to the development and survival of other forms of life. It would be highly relevant to introduce the idea that our cultural evolution and capacity to modify the environment to meet our needs have established new environmental conditions in which the human species' survival and reproduction rate expand at the detriment of ecosystems and endangerment of other primates and non-human species.<\/p>\n<p>According to the International Union for Conservation of Nature\u2019s Red List of Threatened Species, there are currently over 169,000 species listed, with more than 47,000 species at risk of extinction \u2014 including 41% of amphibians, 26% of mammals, 26% of freshwater fishes, 12% of birds, and many others (IUCN, 2025). Human lifestyles are causing changes that\u2014if not taken into consideration\u2014could lead to our extinction as a species. The recognition that our evolutionary behavioural development is causing environmental destruction may be the first step for our species to take accountability for the damage that it is causing to others and prevent further damage.<\/p>\n<\/div>\n<\/div>\n<div class=\"__UNKNOWN__\">\n<h2>Cultural Connections and Contemporary Implications<\/h2>\n<p>From an anthropological perspective, the study of genetics and genomics reveals that human evolution is no longer a purely biological process but a deeply cultural one. The Modern Synthesis brings together both Mendelian genetics and population-level evolutionary theory, demonstrating how discrete genes interact across populations through mutation, migration, selection, and drift. Contemporary research in genomics and epigenetics further expands this view, describing how genes are not fixed determinants, but dynamic, responsive systems shaped by environmental, social, and technological forces. This contemporary framework allows anthropology to see human evolution as a continuing dialogue between biology and culture, in which social life and technology now act as powerful forces.<\/p>\n<p>Technological innovation, particularly in the digital age, represents one of these new forces. The human brain is adapting to a world saturated with digital stimuli, shifting to favor pattern recognition and multitasking over deep memorization or spatial awareness. Beyond cognition, the constants of technology's presence in our daily lives\u2014screen exposure, disrupted sleep, and mediated social interaction\u2014can influence neural development and stress-response pathways, blurring the boundaries between biological and cultural adaptation and suggesting that technology itself has become a profound developmental influence.<\/p>\n<p>It is important to note that climate change exerts another global selective pressure, reshaping ecosystems and human responses to them. Physiological adaptation may involve tolerance to heat and fluctuating food sources, while genetic selection could favour metabolic and immune traits suited to new environments. There will also be large changes from a cultural perspective, where migration, innovation, and social restructuring may have large impacts on human evolution.<\/p>\n<p>Genomic engineering further complicates this picture. Techniques such as CRISPR now allow for the precise alteration of DNA, offering immense potential for eliminating hereditary diseases and improving long-term health outcomes. One example is the targeted suppression of the PCSK9 gene to lower LDL cholesterol levels, which can significantly reduce the risk of heart disease in genetically predisposed individuals (Feldscher, 2022). While such interventions hold great promise for preventive medicine, they also raise evolutionary concerns. By artificially narrowing the range of genetic variation, these technologies may weaken the population\u2019s long-term adaptability. Alleles that appear harmful in one context may confer unexpected advantages under different environmental conditions, and their removal could limit evolutionary flexibility. Moreover, as lifespans lengthen and mortality rates decline, population density and resource strain are likely to increase, shifting selective pressures away from disease resistance and toward ecological sustainability and social equilibrium.<\/p>\n<p>While these aspects are important to take into consideration, it remains uncertain how much such current interventions will truly influence long-term human evolution. Many of their effects may occur only at the individual or generational level. Epigenetic modifications, for instance, often fade during gametogenesis, meaning that changes in gene expression caused by lifestyle, stress, or diet may not be inherited. Likewise, the elimination of certain \u201cpoor\u201d genes through technology may occur only in isolated lineages rather than across populations, limiting their evolutionary impact. Nevertheless, anthropology reminds us that even if these changes do not drastically redirect human evolution, they redefine how humans understand and engage with it. The cultural meanings attached to genetic \u201ccorrection,\u201d optimization, and identity echo older anxieties about purity and control. Moreover, the commercialization of genetic data transforms ancestry and kinship into molecular commodities. Whether or not technology reshapes our genes in the long term, it is already reshaping our concept of what it means to be human\u2014a transformation as cultural and philosophical as it is biological.<\/p>\n<h4>Discussion questions<\/h4>\n<ul>\n<li>In what ways has technology shaped humans both culturally and biologically? Can you think of examples from your own lives or society?<\/li>\n<li>Should humans actively intervene in their own evolution through genetic modification? What potential benefits, risks, and social consequences might this create?<\/li>\n<li>How might climate change influence human evolution, both biologically and culturally? What forms of adaptation might become increasingly important as environments change?<\/li>\n<\/ul>\n<div class=\"textbox shaded\">\n<h2 class=\"import-Normal\">Summary<\/h2>\n<p class=\"import-Normal\">Now that you have finished reading this chapter, you are equipped to understand the historical and political dimensions of evolution. Evolution is an ongoing process of change and diversification. Evolutionary theory is a tool that we use to understand this process. The development of evolutionary theory is shaped both by scientific innovation and political engagement. Since Darwin first articulated natural selection as an observable mechanism by which species adapt to their environments, our understanding of evolution has grown. Initially, scientists focused on the adaptive aspects of evolution. However, with the emergence of genetics, our understanding of heredity and the level at which evolution acts has changed. Genetics led to a focus on the molecular dimensions of evolution. For some, this focus resulted in reductive accounts of evolution. Further developments in our understanding of evolution shifted our view to epigenetic processes and how organisms shape their own evolutionary pressures (e.g., niche construction).<\/p>\n<p class=\"import-Normal\">Evolutionary theory will continue to develop in the future as we invent new technologies, describe new dimensions of biology, and experience cultural changes. Current innovations in evolutionary theory are asking us to consider evolutionary forces beyond natural selection and genetics to include the ways organisms shape their environments (niche construction), inheritances beyond genetics (inclusive inheritance), constraints on evolutionary change (developmental bias), and the ability of bodies to change in response to external factors (plasticity). The future of evolutionary theory looks bright as we continue to explore these and other dimensions. Biological anthropology is well-positioned to be a lively part of this conversation, as it extends standard evolutionary theory by considering the role of culture, social learning, and human intentionality in shaping the evolutionary trajectories of humans (Zeder 2018). Remember, at root, human evolutionary theory consists of two propositions: (1) the human species is descended from other similar species and (2) natural selection has been the primary agent of biological adaptation. Pretty much everything else is subject to some degree of contestation.<\/p>\n<h2 class=\"import-Normal\">Review Questions<\/h2>\n<ul>\n<li class=\"import-Normal\">How is the study of your ancestors biopolitical, not just biological? Does that make it less scientific or differently scientific?<\/li>\n<li class=\"import-Normal\">What was gained by reducing organisms to genotypes and species to gene pools? What is gained by reintroducing bodies and species into evolutionary studies?<\/li>\n<li class=\"import-Normal\">How do genetic or molecular studies complement anatomical studies of evolution?<\/li>\n<li class=\"import-Normal\">How are you reducible to your ancestry? If you could meet your ancestors from the year 1700 (and you would have well over a thousand of them!), would their lives be meaningfully similar to yours? Would you even be able to communicate with them?<\/li>\n<li class=\"import-Normal\">The molecular biologist Fran\u00e7ois Jacob argued that evolution is more like a tinkerer than an engineer. In what ways do we seem like precisely engineered machinery, and in what ways do we seem like jerry-rigged or improvised contraptions?<\/li>\n<li class=\"import-Normal\">How might biological anthropology contribute to future developments in evolutionary theory?<\/li>\n<\/ul>\n<\/div>\n<h2 class=\"import-Normal\">Key Terms<strong><br \/>\n<\/strong><\/h2>\n<p class=\"import-Normal\"><strong>Adaptation<\/strong>: A fit between the organism and environment.<\/p>\n<p class=\"import-Normal\"><strong>Adaptationism<\/strong>: The idea that everything is the product of natural selection.<\/p>\n<p class=\"import-Normal\"><strong>Allele<\/strong>: A genetic variant.<\/p>\n<p class=\"import-Normal\"><strong>Allometry<\/strong>: The differential growth of body parts.<\/p>\n<p class=\"import-Normal\"><strong>Canalization<\/strong>: The tendency of a growing organism to be buffered toward normal development.<\/p>\n<p class=\"import-Normal\"><strong>Epigenetics<\/strong>: The study of how genetically identical cells and organisms (with the same DNA base sequence) can nevertheless differ in stably inherited ways.<\/p>\n<p class=\"import-Normal\"><strong>Eugenics<\/strong>: An idea that was popular in the 1920s that society should be improved by breeding \u201cbetter\u201d kinds of people.<\/p>\n<p class=\"import-Normal\"><strong>Evo-devo<\/strong>: The study of the origin of form; a contraction of \u201cevolutionary developmental biology.\u201d<\/p>\n<p class=\"import-Normal\"><strong>Exaptation<\/strong>: An additional beneficial use for a biological feature.<\/p>\n<p class=\"import-Normal\"><strong>Extinction<\/strong>: The loss of a species from the face of the earth.<\/p>\n<p class=\"import-Normal\"><strong>Gene<\/strong>: A stretch of DNA with an identifiable function (sometimes broadened to include any DNA with recognizable structural features as well).<\/p>\n<p class=\"import-Normal\"><strong>Gene pool<\/strong>: Hypothetical summation of the entire genetic composition of population or species.<\/p>\n<p class=\"import-Normal\"><strong>Genotype<\/strong>: Genetic constitution of an individual organism.<\/p>\n<p class=\"import-Normal\"><strong>Hereditarianism<\/strong>: The idea that genes or ancestry is the most crucial or salient element in a human life. Generally associated with an argument for natural inequality on pseudo-genetic grounds.<\/p>\n<p class=\"import-Normal\"><strong>Hox genes<\/strong>: A group of related genes that control for the body plan of an embryo along the head-tail axis.<\/p>\n<p class=\"import-Normal\"><strong>Inheritance of acquired characteristics<\/strong>: The idea that you pass on the features that developed during your lifetime, not just your genes; also known as Lamarckian inheritance.<\/p>\n<p class=\"import-Normal\"><strong>Natural selection<\/strong>: A consistent bias in survival and fertility, leading to the overrepresentation of certain features in future generations and an improved fit between an average member of the population and the environment.<\/p>\n<p class=\"import-Normal\"><strong>Niche construction<\/strong>: The active engagement by which species transform their surroundings in favourable ways, rather than just passively inhabiting them.<\/p>\n<p class=\"import-Normal\"><strong>Phenotype<\/strong>: Observable manifestation of a genetic constitution, expressed in a particular set of circumstances. The suite of traits of an organism.<\/p>\n<p class=\"import-Normal\"><strong>Phrenology<\/strong>: The 19th-century anatomical study of bumps on the head as an indication of personality and mental abilities.<\/p>\n<p class=\"import-Normal\"><strong>Plasticity<\/strong>: The tendency of a growing organism to react developmentally to its particular conditions of life.<\/p>\n<p class=\"import-Normal\"><strong>Punctuated equilibria<\/strong>: The idea that species are stable through time and are formed very rapidly relative to their duration. (The opposite theory, that species are unstable and constantly changing through time, is called phyletic gradualism.)<\/p>\n<p class=\"import-Normal\"><strong>Scientific racism<\/strong>: The use of pseudoscientific evidence to support or legitimize racial hierarchy and inequality.<\/p>\n<p class=\"import-Normal\"><strong>Sexual selection<\/strong>: Natural selection arising through preference by one sex for certain characteristics in individuals of the other sex.<\/p>\n<p class=\"import-Normal\"><strong>Species selection<\/strong>: A postulated evolutionary process in which selection acts on an entire species population, rather than individuals.<\/p>\n<h2 class=\"import-Normal\">For Further Exploration <strong><br \/>\n<\/strong><\/h2>\n<p class=\"import-Normal\">Ackermann, Rebecca Rogers, Alex Mackay, and Michael L. Arnold. 2016. \u201cThe Hybrid Origin of \u2018Modern\u2019 Humans.\u201d <em>Evolutionary Biology<\/em> 43 (1): 1\u201311.<\/p>\n<p class=\"import-Normal\">Bateson, Patrick, and Peter Gluckman. 2011. <em>Plasticity, Robustness, Development and Evolution<\/em>. New York: Cambridge University Press.<\/p>\n<p class=\"import-Normal\">Cosans, Christopher E. 2009. <em>Owen's Ape and Darwin's Bulldog: Beyond Darwinism and Creationism<\/em>. Bloomington, IN: Indiana University Press.<\/p>\n<p class=\"import-Normal\">Desmond, Adrian, and James Moore. 2009. <em>Darwin's Sacred Cause: How a Hatred of Slavery Shaped Darwin's Views on Human Evolution<\/em>. New York: Houghton Mifflin Harcourt.<\/p>\n<p class=\"import-Normal\">Dobzhansky, Theodosius, Francisco J. Ayala, G. Ledyard Stebbins, and James W. Valentine. 1977. <em>Evolution<\/em>. San Francisco: W.H. Freeman and Company.<\/p>\n<p class=\"import-Normal\">Fuentes, Agust\u00edn. 2017. <em>The Creative Spark: How Imagination Made Humans Exceptional<\/em>. New York: Dutton.<\/p>\n<p class=\"import-Normal\">Haraway, Donna J. 1989. <em>Primate Visions: Gender, Race, and Nature in the World of Modern Science<\/em>. New York: Routledge.<\/p>\n<p class=\"import-Normal\">Huxley, Thomas. 1863. <em>Evidence as to Man's Place in Nature<\/em>. London: Williams &amp; Norgate.<\/p>\n<p class=\"import-Normal\">Jablonka, Eva, and Marion J. Lamb. 2005. <em>Evolution in Four Dimensions: Genetic, Epigenetic, Behavioral, and Symbolic Variation in the History of Life<\/em>. Cambridge, MA: The MIT Press.<\/p>\n<p class=\"import-Normal\">Kuklick, Henrika, ed. 2008. <em>A New History of Anthropology<\/em>. New York: Blackwell.<\/p>\n<p class=\"import-Normal\">Laland, Kevin N., Tobias Uller, Marcus W. Feldman, Kim Sterelny, Gerd B. Muller, Armin Moczek, Eva Jablonka, and John Odling-Smee. 2015. \u201cThe Extended Evolutionary Synthesis: Its Structure, Assumptions and Predictions.\u201d <em>Proceedings of the Royal Society, Series B<\/em> 282 (1813): 20151019.<\/p>\n<p class=\"import-Normal\">Lamarck, Jean Baptiste. 1809. <em>Philosophie Zoologique<\/em>. Paris: Dentu.<\/p>\n<p class=\"import-Normal\">Landau, Misia. 1991. <em>Narratives of Human Evolution<\/em>. New Haven: Yale University Press.<\/p>\n<p class=\"import-Normal\">Lee, Sang-Hee. 2017. <em>Close Encounters with Humankind: A Paleoanthropologist Investigates Our Evolving Species<\/em>. New York: W. W. Norton.<\/p>\n<p class=\"import-Normal\">Livingstone, David N. 2008. <em>Adam's Ancestors: Race, Religion, and the Politics of Human Origins<\/em>. Baltimore: Johns Hopkins University Press.<\/p>\n<p class=\"import-Normal\">Marks, Jonathan. 2015. <em>Tales of the Ex-Apes: How We Think about Human Evolution<\/em>. Berkeley, CA: University of California Press.<\/p>\n<p class=\"import-Normal\">Pigliucci, Massimo. 2009. \u201cThe Year in Evolutionary Biology 2009: An Extended Synthesis for Evolutionary Biology.\u201d <em>Annals of the New York Academy of Sciences<\/em> 1168: 218\u2013228.<\/p>\n<p class=\"import-Normal\">Simpson, George Gaylord. 1949. <em>The Meaning of Evolution: A Study of the History of Life and of Its Significance for Man<\/em>. New Haven: Yale University Press.<\/p>\n<p class=\"import-Normal\">Sommer, Marianne. 2016.<em> History Within: The Science, Culture, and Politics of Bones, Organisms, and Molecules<\/em>. Chicago: University of Chicago Press.<\/p>\n<p class=\"import-Normal\">Stoczkowski, Wiktor. 2002. <em>Explaining Human Origins: Myth, Imagination and Conjecture<\/em>. New York: Cambridge University Press.<\/p>\n<p class=\"import-Normal\">Tattersall, Ian, and Rob DeSalle. 2019. <em>The Accidental Homo sapiens: Genetics, Behavior, and Free Will<\/em>. New York: Pegasus.<\/p>\n<h2 class=\"import-Normal\">References<\/h2>\n<p class=\"import-Normal\">Barton, Robert A. 1996. \"Neocortex Size and Behavioural Ecology in Primates.\" <em>Proceedings of the Royal Society of London. Series B: Biological Sciences<\/em> 263 (1367): 173\u2013177.<\/p>\n<p class=\"import-Normal\">Bodmer, Walter, and Robin McKie. 1997. <em>The Book of Man: The Hman Genome Project and the Quest to Discover our Genetic Heritage.<\/em> Oxford University Press.<\/p>\n<p>Brassard, A., Perron-Laplante, J., Lachapelle, \u00c9., Pierrepont, C. de, &amp; P\u00e9loquin, K. (2018). Oversexualization among emerging adults: Preliminary associations with romantic attachment and intimacy. The Canadian Journal of Human Sexuality, 27(3), 235\u2013247. Project Muse.<\/p>\n<p>Carroll, S. B. (2005). Evolution at Two Levels: On Genes and Form. PLoS Biology, 3(7). Public Library of Science. https:\/\/doi.org\/10.1371\/journal.pbio.0030245<\/p>\n<p>Chudek, M., Muthukrishna, M., &amp; Henrich, J. (2015). Cultural evolution. <em>The Handbook of Evolutionary Psychology<\/em>, 1\u201321. https:\/\/doi.org\/10.1002\/9781119125563.evpsych230<\/p>\n<p class=\"import-Normal\">Darwin, Charles. 1859.<em> On the Origin of Species by Means of Natural Selection, or, the Preservation of Favoured Races in the Struggle for Life<\/em>. London: J. Murray.<\/p>\n<p class=\"import-Normal\">Darwin, Charles. 1871. <em>The Descent of Man, and Selection in Relation to Sex.<\/em> London: J. Murray.<\/p>\n<p class=\"import-Normal\">Dawkins, Richard. 1976. <em>The Selfish Gene. <\/em>Oxford University Press.<\/p>\n<p class=\"import-Normal\">Deacon, T. W. 1998. <em>The Symbolic Species: The Co-evolution of Language and the Brain<\/em>. W. W. Norton &amp; Company.<\/p>\n<p class=\"import-Normal\">Eldredge, N., and S. J. Gould. 1972. \"Punctuated Equilibria: An Alternative to Phyletic Gradualism.\" In <em>Models in Paleobiology<\/em>, edited by T. J. Schopf, 82\u2013115. San Francisco: W. H. Freeman.<\/p>\n<p>Feldscher, K. (2022). <em>Using gene editing to fight deadly genetic diseases<\/em>. Harvard T.H. Chan School of Public Health. https:\/\/hsph.harvard.edu\/news\/using-gene-editing-to-fight-deadly-genetic-diseases\/<\/p>\n<p>Fran\u00e7oso, E., Zuntini, A. R., Ricardo, P. C., Santos, P. K. F., de Souza Araujo, N., Silva, J. P. N., Gon\u00e7alves, L. T., Brito, R., Gloag, R., Taylor, B. A., Harpur, B. A., Oldroyd, B. P., Brown, M. J. F., &amp; Arias, M. C. (2023). Rapid evolution, rearrangements and whole mitogenome duplication in the Australian stingless bees Tetragonula (Hymenoptera: Apidae): A steppingstone towards understanding mitochondrial function and evolution. International Journal of Biological Macromolecules, 242. Elsevier. https:\/\/doi.org\/10.1016\/j.ijbiomac.2023.124568<\/p>\n<p class=\"import-Normal\">Gayon, J. (2010). Sexual selection: Another Darwinian process. Comptes Rendus Biologies, 333(2), 134\u2013144. MEDLINE. https:\/\/doi.org\/10.1016\/j.crvi.2009.12.001<\/p>\n<p>Goldman, E. A., &amp; Sterner, K. N. (2023). Environment, Epigenetics, and the Pace of Human Aging. Annual Review of Anthropology, 52, 279\u2013294. Annual Reviews. https:\/\/doi.org\/10.1146\/annurev-anthro-052721-090516<\/p>\n<p>Gould, S. J., &amp; Eldredge, N. (1977). Punctuated Equilibria: The Tempo and Mode of Evolution Reconsidered. Paleobiology, 3(2), 115\u2013151. JSTOR Biological Sciences Collection.<\/p>\n<p class=\"import-Normal\">Gould, Stephen J. 2003.<em> The Structure of Evolutionary Theory<\/em>. Cambridge, MA: Harvard University Press.<\/p>\n<p class=\"import-Normal\">Gould, Stephen J. 1996. <em>Mismeasure of Man<\/em>. New York: WW Norton &amp; Company.<\/p>\n<p class=\"import-Normal\">Gould, Stephen Jay, and Richard C. Lewontin. 1979. \"The Spandrels of San Marco and the Panglossian Paradigm: A Critique of the Adaptationist Programme.\" <em>Proceedings of the Royal Society of London. Series B: Biological Sciences<\/em> 205 (1151): 581\u2013598.<\/p>\n<p class=\"import-Normal\">Haeckel, Ernst. 1868. <em>Nat\u00fcrliche Sch\u00f6pfungsgeschichte<\/em>. Berlin: Reimer.<\/p>\n<p class=\"import-Normal\">Huxley, Thomas Henry. 1863. <em>Evidence as to Man\u2019s Place in Nature. <\/em>London: Williams and Norgate.<\/p>\n<p>IUCN. 2025. <em>The IUCN Red List of Threatened Species<\/em>. Version 2025-1. https:\/\/www.iucnredlist.org. Accessed on 30 July 2025.<\/p>\n<p class=\"import-Normal\">Kaufman, Thomas C., Mark A. Seeger, and Gary Olsen. 1990. \"Molecular and Genetic Organization of the Antennapedia Gene Complex of <em>Drosophila melanogaster<\/em>.\" <em>Advances in Genetics<\/em> 27: 309\u2013362.<\/p>\n<p class=\"import-Normal\">Kellogg, Vernon. 1917. <em>Headquarters Nights<\/em>. Boston: The Atlantic Monthly Press.<\/p>\n<p class=\"import-Normal\">Kevles, Daniel J., and Leroy Hood. 1993. <em>The Code of Codes: Scientific and Social Issues in the Human Genome Project<\/em>. Cambridge, MA: Harvard University Press.<\/p>\n<p class=\"import-Normal\">Lewontin, Richard, Steven Rose, and Leon Kamin. 2017. <em>Not in Our Genes\u202f: Biology, Ideology, and Human Nature<\/em>, 2nd ed. Chicago: Haymarket Books.<\/p>\n<p class=\"import-Normal\">Lloyd, Elisabeth A., and Stephen J. Gould. 1993. \"Species Selection on Variability.\" <em>Proceedings of the National Academy of Sciences<\/em> 90 (2): 595\u2013599.<\/p>\n<p class=\"import-Normal\">Marks, Jonathan. 2015. \u201cThe Biological Myth of Human Evolution.\u201d In <em>Biologising the Social Sciences: Challenging Darwinian and Neuroscience Explanations<\/em>, edited by David Canter and David A. Turner, 59\u201378. London: Routledge.<\/p>\n<p>Meaney, M. J. (2001). Maternal care, gene expression, and the transmission of individual differences in stress reactivity across generations. Annual Review of Neuroscience, 24, 1161\u20131192. MEDLINE.<\/p>\n<p class=\"import-Normal\">Monypenny, William Flavelle, and George Earle Buckle. 1929. <em>The Life of Benjamin Disraeli, Earl of Beaconsfield, Volume II: 1860\u20131881<\/em>. London: John Murray.<\/p>\n<p class=\"import-Normal\">Potts, Rick. 1998. \u201cVariability Selection in Hominid Evolution.\u201d <em>Evolutionary Anthropology <\/em><em>7<\/em><em>:<\/em> 81\u201396.<\/p>\n<p class=\"import-Normal\">Punnett, R. C. 1905. <em>Mendelism<\/em>. Cambridge: Macmillan and Bowes.<\/p>\n<p>Robbins, R., &amp; Dowty, R. (2019). Robbins Richard, Global problems and culture of capitalism (7th ed.). Pearson.<\/p>\n<p class=\"import-Normal\">Shapiro, Robert. 1991. <em>The Human Blueprint: The Race to Unlock the Secrets of Our Genetic Script.<\/em> New York: St. Martin\u2019s Press.<\/p>\n<p>Schafte, K., &amp; Bruna, S. (2023). The influence of intergenerational trauma on epigenetics and obesity in Indigenous populations\u2014A scoping review. Epigenetics, 18(1), 2260218. MEDLINE. https:\/\/doi.org\/10.1080\/15592294.2023.2260218<\/p>\n<p>Shultz, Susanne, Emma Nelson, and Robin Dunbar. 2012. \"Hominin Cognitive Evolution: Identifying Patterns and Processes in the Fossil and Archaeological Record.\" <em>Philosophical Transactions of the Royal Society B: Biological Sciences<\/em> 367 (1599): 2130\u20132140.<\/p>\n<p>Shook, B., Nelson, K., Braff, L., &amp; Aguilera, K. (2023a). Molecular Biology and Genetics. https:\/\/opentextbooks.concordia.ca\/explorationsversiontwo\/chapter\/3\/<\/p>\n<p>Shook, B., Nelson, K., Braff, L., &amp; Aguilera, K. (2023b). Social and Biopolitical Dimensions of Evolutionary Thinking. https:\/\/opentextbooks.concordia.ca\/explorationsversiontwo\/chapter\/social-and-bi opolitical-dimensions-of-evolutionary-thinking\/<\/p>\n<p class=\"import-Normal\">Spencer, Herbert. 1864. <em>Principles of Biology.<\/em> London: Williams and Norgate.<\/p>\n<p>UNESCO. (2024).<em> The Anthropocene<\/em>. International Union of Geological Sciences. https:\/\/www.iugs.org\/_files\/ugd\/f1fc07_40d1a7ed58de458c9f8f24de5e739663.pdf?index=true<\/p>\n<p>Vicedo, M. (2025). Charlotte Perkins Gilman: A Pragmatist Framework for Constructing a New Humanhood. Journal of the History of the Behavioral Sciences, 61(4), e70041. MEDLINE. https:\/\/doi.org\/10.1002\/jhbs.70041<\/p>\n<p class=\"import-Normal\">Watson, James D. 1990. \"The Human Genome Project: Past, Present, and Future.\" <em>Science<\/em> 248 (4951): 44\u201349.<\/p>\n<p>Wray, G. A. (2007). The evolutionary significance of cis-regulatory mutations. Nature Reviews. Genetics, 8(3), 206\u2013216. MEDLINE.<\/p>\n<p>Waddington CH. Genetic assimilation of the bithorax phenotype. Evolution. 1956;10:1\u201313. doi: 10.1111\/j.1558-5646.1956.tb02824.x.<\/p>\n<p class=\"import-Normal\">Yengo, L., Vedantam, S., Marouli, E., Sidorenko, J., Bartell, E., Sakaue, S., Graff, M., Eliasen, A.U., Jiang, Y., Raghavan, S. and Miao, J., 2022. A saturated map of common genetic variants associated with human height. <em>Nature<\/em>, <em>610 <\/em>(7933): 704-712.<\/p>\n<p class=\"import-Normal\">Zeder, Melinda A. 2018. \"Why Evolutionary Biology Needs Anthropology: Evaluating Core Assumptions of the Extended Evolutionary Synthesis.\" <em>Evolutionary Anthropology: Issues, News, and Reviews<\/em> 27 (6): 267\u2013284.<\/p>\n<\/div>\n<\/div>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1695_1846\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1695_1846\"><div tabindex=\"-1\"><div class=\"__UNKNOWN__\">\n<div class=\"textbox\">\n<h6>Student contributors for this chapter from Salinda Hess' ANTH 203: Daphn\u00e9e-Tiffany Kirouac Millan, Davina Paradis, Jung Jin Kim, and Nathan Dennis<\/h6>\n<p>Learn more about <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/about-the-authors\/\">authors and editors<\/a>,<a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/student-contributors\/\"> Hess' student contributions<\/a>, and <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/versioning-history\/\">versioning history<\/a>.<\/p>\n<\/div>\n<p>&nbsp;<\/p>\n<div class=\"textbox textbox--learning-objectives\">\n<header class=\"textbox__header\">\n<h2 class=\"textbox__title\">Learning Objectives<\/h2>\n<\/header>\n<div class=\"textbox__content\">\n<ul>\n<li>Explain the relationship among genes, bodies, and organismal change.<\/li>\n<li>Discuss the shortcomings of simplistic understandings of genetics.<\/li>\n<li>Describe what is meant by the \"biopolitics of heredity.\"<\/li>\n<li>Discuss issues caused by misuse of ideas about adaptations and natural selection.<\/li>\n<li>Examine and correct myths about evolution.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<p class=\"import-Normal\">The Human Genome Project, an international initiative launched in 1990, sought to identify the entire genetic makeup of our species. For many scientists, it meant trying to understand the genetic underpinnings of what made humans uniquely human. James Watson, a codiscoverer of the helical shape of DNA, wrote that \u201cwhen finally interpreted, the genetic messages encoded within our DNA molecules will provide the ultimate answers to the chemical underpinnings of human existence\u201d (Watson 1990, 248). The underlying message is that what makes humans unique can be found in our <strong>genes<\/strong>. The Human Genome Project hoped to find the core of who we are and where we come from.<\/p>\n<p class=\"import-Normal\">Despite its lofty goal, the Human Genome Project\u2014even after publishing the entire human genome in January 2022\u2014could not fully account for the many factors that contribute to what it is to be human. Richard Lewontin, Steven Rose, and Leon Kamin (2017) argue that genetic determinism of the sort assumed by the Human Genome Project neglects other essential dimensions that contribute to the development and evolution of human bodies, not to mention the role that culture plays. They use an apt metaphor of a cake to illustrate the incompleteness of reductive models. Consider the flavour of a cake and think of the ingredients listed in the recipe. The recipe includes ingredients such as flour, sugar, shortening, vanilla extract, eggs, and milk. Does raw flour taste like cake? Does sugar, vanilla extract, or any of the other ingredients taste like cake? They do not, and knowing the individual flavours of each ingredient does not tell us much about what cake tastes like. Even mixing all of the ingredients in the correct proportions does not get us cake. Instead, external factors such as baking at the right temperature, for the right amount of time, and even the particularities of our evolved sense of taste and smell are all necessary components of experiencing the cake. Lewontin, Rose, and Kamin (2017) argue that the same is true for humans and other organisms.<\/p>\n<p class=\"import-Normal\">Knowing everything about cake ingredients does not allow us to fully know cake. Equally so, knowing everything about the genes found in our DNA does not allow us to fully know humans. Different, interacting levels are implicated in the development and evolution of all organisms, including humans. Genes, the structure of chromosomes, developmental processes, epigenetic tags, environmental factors, and still-other components all play key roles such that genetically reductive models of human development and evolution are woefully inadequate.<\/p>\n<p class=\"import-Normal\">The complex interactions across many levels\u2014genetic, developmental, and environmental\u2014explain why we still do not know how our one-dimensional DNA nucleotide sequence results in a four-dimensional organism. This was the unfulfilled promise of the inception of the Human Genome Project in the 1980s and 1990s: the project produced the complete DNA sequence of a human cell in the hopes that it would reveal how human bodies are built and how to cure them when they are built poorly. Yet, that information has remained elusive. Presumably, the knowledge of how organisms are produced from DNA sequences will one day permit us to reconcile the discrepancies between patterns in anatomical evolution and molecular evolution.<\/p>\n<p class=\"import-Normal\">In this chapter, we will consider multilevel evolution and explore evolution as a complex interaction between genetic and epigenetic factors as well as the environments in which organisms live. Next, we will examine the biopolitical nature of human evolution. We will then investigate problems that arise from attributing all traits to an adaptive function. Finally, we will address common misconceptions about evolution. The goal of this chapter is to provide you with the necessary toolkit for understanding the molecular, anatomical, and political dimensions of evolution.<\/p>\n<h2 class=\"import-Normal\">Evolution Happens at Multiple Levels<\/h2>\n<p class=\"import-Normal\">Following Richard Dawkins\u2019s publication of <em>The Selfish Gene <\/em>in 1976, the scientific imagination was captured by the potential of genomics to reveal how genes are copied by Darwinian selection. Dawkins argues that the genes in individuals that contribute to greater reproductive success are the units of selection. His conception of evolution at the molecular level undercuts the complex interactions between organisms and their environments, which are not expressed genomically but are nevertheless key drivers in evolution.<\/p>\n<p class=\"import-Normal\">By the 1980s, the acknowledgement among most biologists that even though genes construct bodies, genes and bodies evolve at different rates and with distinct patterns. This realization led to a renewed focus on how bodies change. The Evolutionary Synthesis of the 1930s\u20131970s had reduced organisms to their <strong>genotypes<\/strong> and species to their <strong>gene pools<\/strong>, which provided valuable insights about the processes of biological change, but it was only a first approximation. Animals are in fact reactive and adaptable beings, not passive and inert genotypes. Species are clusters of socially interacting and reproductively compatible organisms.<\/p>\n<figure style=\"width: 291px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"https:\/\/opentextbooks.concordia.ca\/explorations\/wp-content\/uploads\/sites\/57\/2023\/06\/image8-5.png\" alt=\"An asteroid hits the ocean. Pterodactyls fly among clouds in the foreground.\" width=\"291\" height=\"233\" \/><figcaption class=\"wp-caption-text\">Figure 3.1: A painting by Donald E. Davis representing the Chicxulub asteroid impact off the Yucatan Peninsula that contributed to the mass extinction that included the dinosaurs about 65 million years ago. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Chicxulub_impact_-_artist_impression.jpg\" target=\"_blank\">Chicxulub impact - artist impression<\/a> by Donald E. Davis, <a href=\"https:\/\/www.nasa.gov\/\" target=\"_blank\">NASA<\/a>, is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\" target=\"_blank\">public domain<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Once we accept that evolutionary change is fundamentally genetic change, we can ask: How do bodies function and evolve? How do groups of animals come to see one another as potential mates or competitors for mates, as opposed to just other creatures in the environment? Are there evolutionary processes that are not explicable by population genetics? These questions\u2014which lead us beyond reductive assumptions\u2014were raised in the 1980s by Stephen Jay Gould, the leading evolutionary biologist of the late 20th century (see: Gould 2003; 1996).<\/p>\n<p class=\"import-Normal\">Gould spearheaded a movement to identify and examine higher-order processes and features of evolution that were not adequately explained by population genetics. For example, <strong>extinction<\/strong>, which was such a problem for biologists of the 1600s, could now be seen as playing a more complex role in the history of life than population genetics had been able to model. Gould recognized that there are two kinds of extinctions, each with different consequences: background extinctions and mass extinctions. Background extinctions are those that reflect the balance of nature, because in a competitive Darwinian world, some things go extinct and other things take their place. Ecologically, your species may be adapted to its niche, but if another species comes along that\u2019s better adapted to the same niche, eventually your species will go extinct. It sucks, but it is the way of all life: you come into existence, you endure, and you pass out of existence. But mass extinctions are quite different. They reflect not so much the balance of nature as the wholesale disruption of nature: many species from many different lineages dying off at roughly the same time\u2014presumably as the result of some kind of rare ecological disaster. The situation may not be survival of the fittest as much as survival of the luckiest. The result, then, would be an ecological scramble among the survivors. Having made it through the worst, the survivors could now simply divide up the new ecosystem amongst themselves, since their competitors were gone. Something like this may well have happened about 65 million years ago, when a huge asteroid hit the Yucatan Peninsula, which mammals survived but dinosaurs did not (Figure 3.1). Something like this may be happening now, due to human expansion and environmental degradation. Note, though, that there is only a limited descriptive role here for population genetics: the phenomena we are describing are about organisms and species in ecosystems.<\/p>\n<p class=\"import-Normal\">Another question involved the disconnect between properties of <em>species<\/em> and the properties of <em>gene pools<\/em>. For example, there are upwards of 15 species of gibbons but only two species of chimpanzees. Why? There are upwards of 20 species of guenons but fewer than ten of baboons. Why? Are there genes for that? It seems unlikely. Gould suggested that species, as units of nature, might have properties that are not reducible to the genes in their cells. For example, rates of speciation and extinction might be properties of their ecologies and histories rather than their genes. Thus, relationships between environmental contexts and variability within a species result in degrees of resistance to extinction and affect the frequency and rates at which clades diversify (Lloyd &amp; Gould 1993). Consistent biases of speciation rates might well produce patterns of macroevolutionary diversity that are difficult to explain genetically and better understood ecologically. Gould called such biases in speciation rates <strong>species selection<\/strong>\u2014a higher-order process that invokes competition between species, in addition to the classic Darwinian competition between individuals.<\/p>\n<p class=\"import-Normal\">One of Gould\u2019s most important studies involved the very nature of species. In the classical view, a species is continually adapting to its environment until it changes so much that it is a different species than it was at the beginning of this sentence (Eldredge &amp; Gould 1972). That implies that the species is a fundamentally unstable entity through time, continuously changing to fit in. But suppose, argued Gould along with paleontologist Niles Eldredge, a species is more stable through time and only really adapts during periods of ecological instability and change. Then we might expect to find in the fossil record long equilibrium periods\u2014a few million years or so\u2014in which species don\u2019t seem to change much, punctuated by relatively brief periods in which they change a bit and then stabilize again as new species. They called this idea <strong>punctuated equilibria<\/strong>. The idea helps to explain certain features of the fossil record, notably the existence of small anatomical \u201cgaps\u201d between closely related fossil forms (Figure 3.2). Its significance lies in the fact that although it incorporates genetics, punctuated equilibria is not really a theory of genetics but one of types bodies in deep time.<\/p>\n<p class=\"import-Normal\">Punctuated equilibria is seen across taxa, with long periods in the fossil record representing little phenotypic change. These periods of stability are disrupted by shorter periods of rapid <strong>adaptation<\/strong>, the process through which populations of organisms become suited to living in their environments. Phenotypic changes are often coupled with drastic climatic or ecological changes that affect the milieu in which organisms live. For example, throughout much of hominin evolutionary history, brain size was closely associated with body size and thus remained mostly stable. However, changes occurred in average hominin brain size at around 100 thousand years ago, 1 million years ago, and 1.8 million years ago. Several hypotheses have been put forth to explain these changes, including unpredictability in climate and environment (Potts 1998), social development (Barton 1996), and the evolution of language (Deacon 1998). Evidence from the fossil record, paleoclimate models, and comparative anatomy suggests that the changes observed in hominin lineage result from biocultural processes\u2014that is, the coalescence of environmental and cultural factors that selected for larger brains (Marks 2015; Shultz, Nelson, &amp; Dunbar 2012).<\/p>\n<figure style=\"width: 461px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"https:\/\/opentextbooks.concordia.ca\/explorations\/wp-content\/uploads\/sites\/57\/2023\/08\/image5-8.png\" alt=\"Two graphs contrast phyletic gradualism and punctuated equilibria.\" width=\"461\" height=\"222\" \/><figcaption class=\"wp-caption-text\">Figure 3.2: Different ways of conceptualizing the evolutionary relationship between an earlier and a later species. With phyletic gradualism, species are envisioned transforming continually in a direct line over time. With punctuated equilibria species branch off at particular points over time.\u00a0 Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__\/\" target=\"_blank\">Phyletic gradualism vs. punctuated equilibria (Figure 2.12)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">In response to the call for a theory of the evolution of form, the field of <strong>evo-devo<\/strong>\u2014the intersection of evolutionary and developmental biology\u2014arose. The central focus here is on how changes in form and shape arise. An embryo matures by the stimulation of certain cells to divide, forming growth fields. The interactions and relationships among these growth fields generate the structures of the body. The <strong>hox genes<\/strong> that regulate these growth fields turn out to be highly conserved across the animal kingdom. This is because they repeatedly turn on and off the most basic genes guiding the animal\u2019s development, and thus any changes to them would be catastrophic. Indeed, these genes were first identified by manipulating them in fruit flies, such that one could produce a bizarre mutant fruit fly that grew a pair of legs where its antennae were supposed to be (Kaufman, Seeger, and Olsen 1990).<\/p>\n<p class=\"import-Normal\">Certain genetic changes can alter the fates of cells and the body parts, while other genetic changes can simply affect the rates at which neighbouring groups of cells grow and divide, thus producing physical bumps or dents in the developing body. The result of altering the relationships among these fields of cellular proliferation in the growing embryo is <strong>allometry<\/strong>, or the differential growth of body parts. As an animal gets larger\u2014either over the course of its life or over the course of macroevolution\u2014it often has to change shape in order to live at a different size. Many important physiological functions depend on properties of geometric area: the strength of a bone, for example, is proportional to its cross-sectional area. But area is a two-dimensional quality, while growing takes place in three dimensions\u2014as an increase in mass or volume. As an animal expands, its bones necessarily weaken, because volume expands faster than area does. Consequently a bigger animal has more stress on its bones than a smaller animal does and must evolve bones even thicker than they would be by simply scaling the animal up proportionally. In other words, if you expand a mouse to the size of an elephant, it will nevertheless still have much thinner bones than the elephant does. But those giant mouse bones will unfortunately not be adequate to the task. Thus, a giant mouse would have to change aspects of its form to maintain function at a larger size (see Figure 3.3).<\/p>\n<p class=\"import-Normal\"><img class=\"aligncenter\" src=\"https:\/\/opentextbooks.concordia.ca\/explorations\/wp-content\/uploads\/sites\/57\/2023\/08\/image6-6.png\" alt=\"Side-view of a mouse skeleton.\" width=\"515\" height=\"252\" \/><\/p>\n<figure style=\"width: 453px\" class=\"wp-caption aligncenter\"><img src=\"https:\/\/opentextbooks.concordia.ca\/explorations\/wp-content\/uploads\/sites\/57\/2023\/08\/image7-9.png\" alt=\"Side-view of an elephant skeleton.\" width=\"453\" height=\"326\" \/><figcaption class=\"wp-caption-text\">Figure 3.3: Mouse (top) and elephant (bottom) skeletons. Notice the elephant\u2019s bones are more robust when the two animals are the same size. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__\/\" target=\"_blank\">Mouse and elephant skeletons (Figure 2.13)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Physiologically, we would like to know how the body \u201cknows\u201d when to turn on and off the genes that regulate growth to produce a normal animal. Evolutionarily, we would like to know how the body \u201clearns\u201d to alter the genetic on\/off switch (or the genetic \u201cslow down\/speed up\u201d switch) to produce an animal that looks different. Moreover, since organisms differ from one another, we would like to know how the developing body distinguishes a range of normal variation from abnormal variation. And, finally, how does abnormal variation eventually become normal in a descendant species?<\/p>\n<p class=\"import-Normal\">Taking up these questions, Gould invoked the work of a British geneticist named Conrad H. Waddington, who thought about genetics in less reductive ways than his colleagues. Rather than isolate specific DNA sites to analyse their function, Waddington instead studied the inheritance of an organism\u2019s reactivity\u2014its ability to adapt to the circumstances of its life. In a famous experiment, he grew fruit fly eggs in an atmosphere containing ether. Most died, but a few survived somehow by developing a weird physical feature: a second thorax with a second pair of wings. Waddington bred these flies and soon developed a stable line of flies who would reliably develop a second thorax when grown in ether. Then he began to lower the concentration of ether, while continuing to selectively breed the flies that developed the strange appearance. Eventually he had a line of flies that would stably develop the \u201cbithorax\u201d <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1238\"><strong>phenotype<\/strong><\/a>\u2013the suite of traits of an organism\u2013even when there was no ether; it had become the \u201cnew normal.\u201d The flies had genetically assimilated the bithorax condition.<\/p>\n<p class=\"import-Normal\">Waddington was thus able to mimic the <strong>inheritance of acquired characteristics<\/strong>: what had been a trait stimulated by ether a few generations ago was now a normal part of the development of the descendants. Waddington recognized that while he had performed a selection experiment on genetic variants, he had not selected for particular traits. Rather, he helped produce the physiological tendency to develop particular traits when appropriately stimulated. He called that tendency <strong>plasticity<\/strong> and its converse, the tendency to stay the same even under weird environmental circumstances, <strong>canalization.<\/strong> Waddington had initially selected for plasticity, the tendency to develop the bithorax phenotype under weird conditions, and then, later, for canalization, the developmental normalization of that weird physical trait. Although Waddington had high stature in the community of geneticists, evolutionary biologists of the 1950s and 1960s regarded him with suspicion because he was not working within the standard mindset of reductionism, which saw evolution as the spread of genetic variants that coded for favourable traits. Both Waddington and Gould resisted contemporary intellectual paradigms that favoured reductive accounts of evolutionary processes. They conceived of evolution as an emergent process in which many external factors (e.g. climate, environment, predation) and internal factors (e.g., genotypes, plasticity, canalization) coalesce to produce the evolutionary trends that we observe in the fossil record and our genome.<\/p>\n<p class=\"import-Normal\">While Gould and Waddington both looked beyond the genome to understand evolution, the Human Genome Project\u2014an international project with the goal of identifying each base pair in the human genome in the 1990s\u2014generated a great deal of public interest in analyzing the human DNA sequence from the standpoint of medical genetics. Some of the rhetoric aimed to sell the public on investing a lot of money and resources in sequencing the human genome in order to show the genetic basis of heritable traits, cure genetic diseases, and learn what it means ultimately to be biologically human. However, the Human Genome Project was not actually able to answer those questions through the use of genetics alone, and thus a broader, more holistic account was required.<\/p>\n<p class=\"import-Normal\">This holistic account came from decades of research in human biology and anthropology, which understood the human body as highly adaptable, dynamic, and emergent. For example, in the early 20th century, anthropologist Franz Boas measured the skulls of immigrants to the U.S., revealing that environmental, not merely genetic, factors affected skull shape. The growing human body adjusts itself to the conditions of life, such as diet, sunshine, high altitude, hard labour, population density, how babies are carried\u2014any and all of which can have subtle but consistent effects upon its development. There can thus be no normal human form, only a context-specific range of human forms.<\/p>\n<p class=\"import-Normal\">However, what the human biologists called human adaptability, evolutionary biologists called developmental plasticity, and evidence quickly began to mount for its cause being <strong>epigenetic <\/strong>modifications to DNA. Epigenetic modifications are changes to how genes are used by the body (as opposed to changes in the DNA sequences; see Chapter 4). Scientific interest shifted from the focus of the Human Genome Project to the ways that bodies are made by evolutionary-developmental processes, including epigenetics. What is meant by \u201cepigenetic modification\u201d? Evolution is about how descendants diverge from their ancestors. Inheritance from parent to offspring is still critical to this process, which occurs through genetic recombination: the pairing of homologous chromosomes and sharing of genetic material during meiosis (see Chapter 4). However, in the 21st century, the link between evolution and inheritance has broadened with a clearer understanding of how environmental and developmental factors shape bodies and the expression of genes, including epigenetic inheritance patterns. While offspring inherit their genes through random assortment during meiosis, environmental factors also shape how genes are used. When these epigenetic modifications occur in germ cells, they can be passed onto offspring. In these cases, there is no change in the DNA sequence but rather in how genes are used by the body due to DNA methylation and the structure of chromosomes due to histone acetylation (see Chapter 4).<\/p>\n<p class=\"import-Normal\">In addition, we now recognize that evolution is affected by two other forms of intergenerational transmission and inheritance (in addition to genetics and epigenetics). These forms include behavioural variation and culture. That is, behavioural information can be transmitted horizontally (intragenerationally), permitting more rapid ways for organisms to adjust to the environment. And, then there is the fourth mode of transmission: the cultural or symbolic mode. It is proposed that humans are the only species that horizontally transmits an arbitrary set of rules to govern communication, social interaction, and thought. This shared information is symbolic and has resulted in what we recognize as \u201cculture\u201d: locally emergent worlds of names, words, pictures, classifications, revered pasts, possible futures, spirits, dead ancestors, unborn descendants, in-laws, politeness, taboo, justice, beauty, and story, all accompanied by practices and a material world of tools.<\/p>\n<p class=\"import-Normal\">Consequently our contemporary ideas about evolution see the evolutionary processes as hierarchically organized and not restricted to the differential transmission of DNA sequences into the next generation. While that is indeed a significant part of evolution, the organism and species are nevertheless crucial to understanding how those DNA sequences get transmitted. Further, the transmission of epigenetic, behavioural, and symbolic information play a complex role in perpetuating our genes, bodies, and species. In the case of human evolution, one can readily see that symbolic information and cultural adaptation are far more central to our lives and our survival today than DNA and genetic adaptation. It is thus misleading to think of humans passively occupying an environmental niche. Rather, humans are actively engaged in constructing our own niches, as well as adapting to them and using them to adapt. The complex interplay between a species and its active engagement in creating its own ecology is known as <strong>niche construction<\/strong>. If we understand <strong>natural selection<\/strong>\u2013the process by which populations adapt to their specific environments\u2013as the effects that environmental context has on the reproductive success of organisms, then niche construction is the process through which organisms shape their own selective pressures.<\/p>\n<div class=\"textbox\">\n<h2>Dig Deeper: Moving Beyond Genetic Determinism<\/h2>\n<p>Contemporary evolutionary biology and anthropology increasingly emphasize that genes operate within dynamic regulatory networks rather than acting as isolated determinants. As <a href=\"https:\/\/www.zotero.org\/google-docs\/?zoqFM1\" target=\"_blank\">Carroll (2005)<\/a> and <a href=\"https:\/\/www.zotero.org\/google-docs\/?C6NEFg\" target=\"_blank\">Wray (2007)<\/a> demonstrate, evolutionary change often arises not from mutations in structural genes but in their regulation\u2014the timing, intensity, and location of gene expression. Such regulatory evolution can explain major anatomical and physiological innovations without invoking large genetic divergences. This view reframes evolution as an outcome of organizational complexity where genetic, developmental, and environmental processes intersect. This systems-level understanding also resonates with anthropological frameworks of biocultural embodiment, which recognize that social and ecological experiences can become biologically inscribed in the body. <a href=\"https:\/\/www.zotero.org\/google-docs\/?AROEum\" target=\"_blank\">Meaney\u2019s (2001)<\/a>\u00a0 foundational epigenetic research focuses on maternal care in rats, presenting how nurturing behaviour modifies the expression of stress-response genes. This biological effect can persist into subsequent generations.<\/p>\n<p>Recent human studies continue to expand this insight. <a href=\"https:\/\/www.zotero.org\/google-docs\/?r3ZGNw\" target=\"_blank\">Goldman &amp; Sterner (2023)<\/a> demonstrate how environmental exposures, inequality, and psychological stress influence the pace of biological aging, showing epigenetic modifications reflect the lived conditions of bodies over time. In Canada, this relationship between environment, history, and biology has profound implications. A 2023 scoping review on Canadian Indigenous populations and the epigenetic effects of intergenerational trauma <a href=\"https:\/\/www.zotero.org\/google-docs\/?NEGUdK\" target=\"_blank\">(Schafte &amp; Bruna, 2023)<\/a> documents measurable biological patterns associated with colonial violence, displacement, and systemic inequity. By dissecting the obesity patterns in the Indigenous youth populations, the researchers present a clear connection between the parents who attended residential schools and biological health issues in their children years later. This holistic understanding of epigenetics shows an \u201cembodied transmission of trauma and ill health across generations\u201d (2023, p.9), underscoring that the effects of colonialism are not merely social but are biologically embodied, carried forward through mechanisms of gene regulation and stress physiology.<\/p>\n<p>Understanding heredity as a process of interaction and regulation rather than genetic determinism opens the door to rethinking evolution as a flexible, context-driven phenomenon. Just as social experiences and ecological conditions can shape patterns of gene expression, environmental pressures can also influence the structure and behaviour of genomes across generations. This broader view of evolutionary change highlights the importance of considering mechanisms that fall outside of traditional, gradualist models.<\/p>\n<\/div>\n<h2 class=\"import-Normal\">The Biopolitics of Heredity<\/h2>\n<p class=\"import-Normal\">\u201cScience isn\u2019t political\u201d is a sentiment that you have likely heard before. Science is supposed to be about facts and objectivity. It exists, or at least ought to, outside of petty human concerns. However, the sorts of questions we ask as scientists, the problems we choose to study, the categories and concepts we use, who gets to do science, and whose work gets cited are all shaped by culture. Doing science is a political act. This fact is markedly true for human evolution. While it is easier to create intellectual distance between us and fruit flies and viruses, there is no distance when we are studying ourselves. The hardest lesson to learn about human evolution is that it is intensely political. Indeed, to see it from the opposite side, as it were, the history of creationism\u2014the belief that the universe was divinely created around 6,000 years ago\u2014is essentially a history of legal decisions. For instance, in <em>Tennessee v. John T. Scopes<\/em> (1925), a schoolteacher was prosecuted for violating a law in Tennessee that prohibited the teaching of human evolution in public schools, where teachers were required by law to teach creationism.<\/p>\n<p class=\"import-Normal\">More recently, legal decisions aimed at legislating science education have shaped how students are exposed to evolutionary theory. For instance, <em>McLean v. Arkansas<\/em> (1982) dispatched \u201cscientific creationism\u201d by arguing that the imposition of balanced teaching of evolution and creationism in science classes violates the Establishment Clause, separating church and state. Additionally, <em>Kitzmiller v. Dover (Pennsylvania) Area School District<\/em> (2005) dispatched the teaching of \u201cintelligent design\u201d in public school classrooms as it was deemed to not be science. In some cases, people see unbiblical things in evolution, although most Christian theologians are easily able to reconcile science to the Bible. In other cases, people see immoral things in evolution, although there is morality and immorality everywhere. And some people see evolution as an aspect of alt-religion, usurping the authority of science in schools to teach the rejection of the Christian faith, which would be unconstitutional due to the protected separation of church and state.<\/p>\n<p class=\"import-Normal\">Clearly, the position that politics has nothing to do with science is untenable. But is the politics in evolution an aberration or is it somehow embedded in science? In the early 20th century, scientists commonly promoted the view that science and politics were separate: science was seen as a pure activity, only rarely corrupted by politics. And yet as early as World War I, the politics of nationalism made a hero of the German chemist Fritz Haber for inventing poison gas. And during World War II, both German doctors and American physicists, recruited to the war effort, helped to end many civilian lives. Therefore, we can think of the apolitical scientist as a self-serving myth that functions to absolve scientists of responsibility for their politics. The history of science shows how every generation of scientists has used evolutionary theory to rationalize political and moral positions. In the very first generation of evolutionary science, Darwin\u2019s <em>Origin of Species<\/em> (1859) is today far more readable than his <em>Descent of Man<\/em> (1871). The reason is that Darwin consciously purged <em>The Origin of Species<\/em> of any discussion of people. And when he finally got around to talking about people, in <em>The Descent of Man<\/em>, he simply imbued them with the quaint Victorian prejudices of his age, and the result makes you cringe every few pages. There is plenty of politics in there\u2014sexism, racism, and colonialism\u2014because <em>you cannot talk about people apolitically<\/em>.<\/p>\n<p class=\"import-Normal\">One immediate faddish deduction from Darwinism, popularized by Herbert Spencer (1864) as \u201csurvival of the fittest,\u201d held that unfettered competition led to advancement in nature and to human history. Since the poor were purported losers in that struggle, anything that made their lives easier would go against the natural order. This position later came to be known ironically as \u201cSocial Darwinism.\u201d Spencer was challenged by fellow Darwinian Thomas Huxley (1863), who agreed that struggle was the law of the jungle but observed that we don\u2019t live in jungles anymore. The obligation to make lives better for others is a moral, not a natural, fact. We simultaneously inhabit a natural universe of descent from apes and a moral universe of injustice and inequality, and science is not well served by ignoring the latter.<\/p>\n<p class=\"import-Normal\">Concurrently, the German biologist Ernst Haeckel\u2019s 1868 popularization of Darwinism was translated into English a few years later as <em>The History of Creation<\/em>. As we saw earlier, Haeckel was determined to convince his readers that they were descended from apes, even in the absence of fossil evidence attesting to it. When he made non-Europeans into the missing links that connected his readers to the apes, and depicted them as ugly caricatures, he knew precisely what he was doing. Indeed, even when the degrading racial drawings were deleted from the English translation of his book, the text nevertheless made his arguments quite clear. And a generation later, when the Americans had not yet entered the Great War in 1916, a biologist named Vernon Kellogg visited the German High Command as a neutral observer and found that the officers knew a lot about evolutionary biology, which they had gotten from Haeckel and which rationalized their military aggressions. Kellogg went home and wrote a bestseller about it, called <em>Headquarters Nights<\/em> (1917). World War I would have been fought with or without evolutionary theory, but as a source of scientific authority, evolution\u2014even if a perversion of the Darwinian theory\u2014had very quickly attained global geopolitical relevance.<\/p>\n<p class=\"import-Normal\">Oftentimes, politics in evolutionary science is subtle, due to the pervasive belief in the advancement of science. We recognize the biases of our academic ancestors and modify our scientific stories accordingly. But we can never be free of our own cultural biases, which are invisible to us, as much as our predecessors\u2019 biases were invisible to them. In some cases, the most important cultural issues resurface in different guises each generation, like scientific racism. <strong>Scientific racism<\/strong> is the recruitment of science for the evil political ends of racism, and it has proved remarkably impervious to evolution. Before Darwin, there was creationist scientific racism, and after Darwin, there was evolutionist scientific racism. And there is still scientific racism today, self-justified by recourse to evolution, which means that scientists have to be politically astute and sensitive to the uses of their work to counter these social tendencies.<\/p>\n<p class=\"import-Normal\">Consider this: Are you just your ancestry, or can you transcend it? If that sounds like a weird question, it was actually quite important to a turn-of-the-20th-century European society in which an old hereditary aristocracy was under increasing threat from a rising middle class. And that is why the very first English textbook of Mendelian genetics concluded with the thought that \u201cpermanent progress is a question of breeding rather than of pedagogics; a matter of gametes, not of training \u2026 the creature is not made but born\u201d (Punnett 1905, 60). <em>Translation: Not only do we now know a bit about how heredity works, but it\u2019s also the most important thing about you. Trust me, I\u2019m a scientist.<\/em><\/p>\n<p class=\"import-Normal\">Yet evolution is about how descendants come to differ from ancestors. Do we really know that your heredity, your DNA, your ancestry, is the most important thing about you? That you were born, not made? After all, we do know that you could be born into slavery or as a peasant, and come from a long line of enslaved people or peasants, and yet not have slavery or peasantry be the most important thing about you. Whatever your ancestors were may unfortunately constrain what you can become, but as a moral precept, it should not. But just as science is not purely \u201cfacts and objectivity,\u201d ancestry is not a strictly biological concept. Human ancestry is biopolitics, not biology.<\/p>\n<p class=\"import-Normal\">Evolution is fundamentally a theory about ancestry, and yet ancestors are, in the broad anthropological sense, sacred: ancestors are often more meaningful symbolically than biologically. Just a few years after <em>The Origin of Species <\/em>(Darwin 1859), the British politician and writer Benjamin Disraeli declared himself to be on the side of the angels, not the apes, and to \u201crepudiate with indignation and abhorrence those new-fangled theories\u201d (Monypenny, Flavelle, and Buckle 1920, 105). He turned his back on an ape ancestry and looked to the angel; yet, he did so as a prominent Jew-turned-Anglican, who had personally transcended his humble roots and risen to the pinnacle of the Empire. Ancestry was certainly important, and Disraeli was famously proud of his, but it was also certainly not the most important thing, not the primary determinant of his place in the world. Indeed, quite the opposite: Disraeli\u2019s life was built on the transcendence of many centuries of Jewish poverty and oppression in Europe. Humble ancestry was there to be superseded and nobility was there to be earned; Disraeli would later become the Earl of Beaconsfield. Clearly, \u201care you just your ancestry\u201d is not a value-neutral question, and \u201cthe creature is not made, but born\u201d is not a value-neutral answer.<\/p>\n<p class=\"import-Normal\">Ancestry being the most important thing about a person became a popular idea twice in 20th century science. First, at the beginning of the century, when the <strong>eugenics<\/strong> movement in America called attention to \u201cfeeble-minded stocks,\u201d which usually referred to the poor or to immigrants (see Figure 3.4). This movement culminated in Congress restricting the immigration of \u201cfeeble-minded races\u201d (said to include Jews and Italians) in 1924, and the Supreme Court declaring it acceptable for states to sterilize their \u201cfeeble-minded\u201d citizens involuntarily in 1927. After the Nazis picked up and embellished these ideas during World War II, Americans moved swiftly away from them in some contexts (e.g., for most people of European descent) while still strictly adhering in other contexts such as Japanese internment camps and immigration restrictions.<\/p>\n<figure style=\"width: 374px\" class=\"wp-caption alignright\"><img class=\"\" src=\"https:\/\/opentextbooks.concordia.ca\/explorations\/wp-content\/uploads\/sites\/57\/2023\/08\/image4-6.png\" alt=\"Historic photo. People sit in front of a structure with a \u201cEugenic and Health Exhibit&quot; banner.\" width=\"374\" height=\"262\" \/><figcaption class=\"wp-caption-text\">Figure 3.4: Eugenic and Health Exhibit, Fitter Families exhibit, and examination building, Kansas State Free Fair. Credit: <a href=\"https:\/\/www.dnalc.org\/view\/16328-Gallery-14-Eugenics-Exhibit-at-the-Kansas-State-Free-Fair-1920.html\" target=\"_blank\">Gallery 14: Eugenics Exhibit at the Kansas State Free Fair, 1920 ID (ID 16328)<\/a> by <a href=\"https:\/\/www.dnalc.org\/\" target=\"_blank\">Cold Spring Harbor<\/a> (Courtesy American Philosophical Society) is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-nd\/3.0\/us\/\" target=\"_blank\">CC BY-NC-ND 3.0 License.<\/a><\/figcaption><\/figure>\n<p class=\"import-Normal\">Ancestry again became paramount in the drumming up of public support for the Human Genome Project in the 1990s. Public support for sequencing the human genome was encouraged by a popular science campaign that featured books titled <em>The Book of Man <\/em>(Bodmer &amp; McKie 1997), <em>The Human Blueprint <\/em>(Shapiro 1991), and <em>The Code of Codes<\/em> (Kevles &amp; Hood 1993). These books generally promised cures for genetic diseases and a deeper understanding of the human condition. We can certainly identify progress in molecular genetics over the last couple of decades since the human genome was sequenced, but that progress has notably not been accompanied by cures for genetic diseases, nor by deeper understandings of the human condition.<\/p>\n<p class=\"import-Normal\">Even at the most detailed and refined levels of genetic analysis, we still don\u2019t have much of an understanding of the actual basis by which things seem to \u201crun in families.\u201d While the genetic basis of simple, if tragic, genetic diseases have become well-known\u2014such as sickle-cell anemia, cystic fibrosis, and Tay-Sachs\u2019 Disease\u2014we still haven\u2019t found the ostensible genetic basis for traits that are thought to have a strong genetic component. For example, a recent genetic summary found over 12,000 genetic sites that contributed to height yet still explained only about 40-50 percent of the variation in height among European ancestry but no more than 10-20 percent of variation of other ancestries, which we know strongly runs in families (Yengo Et al. 2022).<\/p>\n<p class=\"import-Normal\">Partly in reaction to the reductionistic hype of the Human Genome Project, the study of epigenetics has become the subject of great interest. One famous natural experiment involves a Nazi-imposed famine in Holland over the winter of 1944\u20131945. Children born during and shortly after the famine experienced a higher incidence of certain health problems as adults, many decades later. Apparently, certain genes had been down-regulated early in development and remained that way throughout the course of life. Indeed, this modified regulation of the genes in response to the severe environmental conditions may have been passed on to their children.<\/p>\n<p class=\"import-Normal\">Obviously one\u2019s particular genetic constitution may play an important role in one\u2019s life trajectory. But overvaluing that role may have important social and political consequences. In the first place, genotypes are rendered meaningful in a cultural universe. Thus, if you live in a strongly patriarchal society and are born without a Y chromosome (since human males are chromosomally XY and females XX), your genotype will indeed have a strong effect upon your life course. So even though the variation is natural, the consequences are political. The mediating factors are the cultural ideas about how people of different sexes ought to be treated, and the role of the state in permitting certain people to develop and thrive. More broadly, there are implications for public education if variation in intelligence is genetic. There are implications for the legal system if criminality is genetic. There are implications for the justice system if sexual preference, or sexual identity, is genetic. There are implications for the development of sports talent if that is genetic. And yet, even for the human traits that are more straightforward to measure and known to be strongly heritable, the DNA base sequence variation seems to explain little.<\/p>\n<p class=\"import-Normal\">Genetic determinism or <strong>hereditarianism<\/strong> is the idea that \u201cthe creature is made, not born\u201d\u2014or, in a more recent formulation by James Watson, that \u201cour fate is in our genes.\u201d One of the major implications drawn from genetic determinism is that the feature in question must inevitably express itself; therefore, we can\u2019t do anything about it. Therefore, we might as well not fund the social programs designed to ameliorate economic inequality and improve people\u2019s lives, because their courses are fated genetically. And therefore, they don\u2019t deserve better lives.<\/p>\n<p class=\"import-Normal\">All of the \u201ctherefores\u201d in the preceding paragraph are open to debate. What is important is that the argument relies on a very narrow understanding of the role of genetics in human life, and it misdirects the causes of inequality from cultural to natural processes. By contrast, instead of focusing on genes and imagining them to place an invisible limit upon social progress, we can study the ways in which your DNA sequence does <em>not<\/em> limit your capability for self-improvement or fix your place in a social hierarchy. In general, two such avenues exist. First, we can examine the ways in which the human body responds and reacts to environmental variation: human adaptability and plasticity. This line of research began with the anthropometric studies of immigrants by Franz Boas in the early 20th century and has now expanded to incorporate the epigenetic inheritance of modified human DNA. And second, we can consider how human lives are shaped by social histories\u2014especially the structural inequalities within the societies in which they grow up.<\/p>\n<p class=\"import-Normal\">Although it arises and is refuted every generation, the radical hereditarian position (genetic determinism) perennially claims to speak for both science and evolution. It does not. It is the voice of a radical fringe\u2014perhaps naive, perhaps evil. It is not the authentic voice of science or of evolution. Indeed, keeping Charles Darwin\u2019s name unsullied by protecting it from association with bad science often seems like a full-time job. Culture and epigenetics are very much a part of the human condition, and their roles are significant parts of the complete story of human evolution.<\/p>\n<div class=\"textbox\" style=\"background: var(--lightblue)\">\n<h2><strong>Special Topic: Oversexing the Gendered Body <\/strong><\/h2>\n<p>While rapid mitochondrial evolution underscores the biological flexibility of organisms in response to environmental pressures, evolutionary theory is also shaped by another set of forces: cultural assumptions and social norms. Nowhere is this more visible than in scientific interpretations of sex and gender. Many modern gender roles stem from assumptions about sex differences that have accumulated throughout human history. While these roles may appear to be fixed stereotypes or biologically predetermined, they can be deconstructed by examining the processes of sexual selection through queer and feminist theoretical frameworks. Applying these lenses to evolutionary concepts allows for a deeper understanding of how cultural ideologies, particularly those surrounding gender and sexuality, shape interpretations of biological processes.<\/p>\n<p>Darwin first introduced the concept of sexual selection in The Descent of Man (1871) to explain how males and females may have developed different traits that would be detrimental to the species\u2019 overall survival <a href=\"https:\/\/www.zotero.org\/google-docs\/?GVyarx\" target=\"_blank\">(Vicedo, 2025)<\/a>. Unlike natural selection which is \u201cselection by death,\u201d sexual selection represents death by selection <a href=\"https:\/\/www.zotero.org\/google-docs\/?G5vjwZ\" target=\"_blank\">(Gayon, 2010)<\/a>. Darwin argued that males typically compete intrasexually for female attention, and that females exercise choice based on attractiveness or vigor, proving their fitness. However, when reframed through feminist theory, the amount of agency Darwin ascribed to females doesn\u2019t reflect the societal assumptions surrounding gender roles in his era. Charlotte Perkins Gilman in her publication Women and Economics, argued that by the 1960s, men increasingly relied on social dominance over women rather than competition with other men (Vicedo, 2025). This dynamic required women to continually enhance their sexual appeal in exchange for economic security, a system she coined the \u201csexuo-economic relationship\u201d (2025, p.5). This framework reveals the societal power imbalance between men and women, and how women are the ones sexualizing themselves and competing for partners, not men. Such processes would lead to the modern oversexualization of women.<\/p>\n<p>Oversexualization, a cultural ideology that prioritizes sexual appeal over autonomy and well-being, further complicates interpretations of sexual selection. Brassard and company (2018) define oversexualization through four components: valuing people solely for their sexual appeal, societal norms of equating attractiveness with sexiness, sexual objectification, and the inappropriate imposition of sexuality (Brassard Et al., 2018, p.16-17). When oversexualization is observed within a population, it may signal that the pressures of sexual selection have intensified relative to that of natural selection, creating \u201cexcessive sex difference\" (Vicedo,<a href=\"https:\/\/www.zotero.org\/google-docs\/?a1BV2F\" target=\"_blank\"> 2025)<\/a>. While many aspects of Gilman's arguments do not directly apply to contemporary gender dynamics, stereotypes rooted in historical gender expectations continue to shape women's experiences in the workforce and broader society (2025). Understanding sexual selection as a culturally mediated process, rather than as a simple competition amongst males, offers a more nuanced picture of how gender ideologies influence biological narratives. This intersection of culture and biology is crucial for studying gender roles, queer relationships, and sexual diversity across societies and time periods.<\/p>\n<\/div>\n<p>&nbsp;<\/p>\n<div class=\"__UNKNOWN__\">\n<h2 class=\"import-Normal\">Adaptationism and the Panglossian Paradigm<\/h2>\n<p class=\"import-Normal\">The story of human evolution, and the evolution of all life for that matter, is never settled because evolution is ongoing. Additionally, because the conditions that shape evolutionary trajectories are not predetermined, evolution itself is emergent. Even during periods of ecological stability, when fewer macroevolutionary changes occur, populations of organisms continue to experience change. When ecological stability is disrupted, populations must adapt to the changes. Darwin explained in naturalistic terms how animals adapt to their environments: traits that contribute to an organism's ability to survive and reproduce in specific environments will become more common. The most \u201cfit\u201d\u2014those organisms best suite<\/p>\n<figure style=\"width: 279px\" class=\"wp-caption alignright\"><img class=\"\" src=\"https:\/\/opentextbooks.concordia.ca\/explorations\/wp-content\/uploads\/sites\/57\/2023\/08\/image3-5.png\" alt=\"Human hand is smaller with smaller fingers and smoother skin compared to a chimpanzee hand.\" width=\"279\" height=\"264\" \/><figcaption class=\"wp-caption-text\">Figure 3.5: Drawings of a human hand (left) and a chimpanzee hand (right). Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__\/\" target=\"_blank\">Human and chimpanzee hand (Figure 2.16)<\/a> by Mary Nelson original to <a href=\"https:\/\/explorations.americananthro.org\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">d to the <em>current<\/em> environmental conditions in which they live\u2014have survived over eons of the history of life on earth to cocreate ecosystems full of animals and plants. Our own bodies are full of evident adaptations: eyes for seeing, ears for hearing, feet for walking on, and so forth.<\/p>\n<p class=\"import-Normal\">But what about hands? Feet are adapted to be primarily weight-bearing structures (rather than grasping structures, as in the apes) and that is what we primarily use them for. But we use our hands in many ways: for fine-scale manipulation, greeting, pointing, stimulating a sexual partner, writing, throwing, and cooking, among other uses. So which of these uses express what hands are \u201cfor,\u201d when all of them express what hands do?<\/p>\n<p class=\"import-Normal\">Gould and Lewontin (1979) illustrate the problem with assuming that the function of a trait defines its evolutionary cause. Consid<\/p>\n<p class=\"import-Normal\">er the case of Dr. Pangloss\u2014the protagonistic of Voltaire\u2019s <em>Candide<\/em>\u2014who believed that we lived in the best of all possible worlds. Gould and Lewontin use his pronouncement that \u201cnoses were made for spectacles and so we have spectacles\u201d to demonstrate the problem with assuming any trait has evolved for a specific purpose. Identifying a function of a trait does not necessitate that the function is the ultimate cause of the trait. Individual traits are not under selection pressures in isolation; in fact, an entire organism must be able to survive and reproduce in their environment. When natural selection results in adaptations, changes that occur in some traits can have cascading effects throughout the phenotype and features that are not under selection pressure can also change.<\/p>\n<p>&nbsp;<\/p>\n<div class=\"textbox\" style=\"background: var(--lightblue)\">\n<h2>Dig Deeper: Rapid Mitochondrial Evolution in Stingless Bees<\/h2>\n<p>A striking example of this interactional evolutionary change comes from recent research on stingless bees. When observing the mitochondrial genome (mitogenome) in two Australian stringless bees in the genus Tetragonula\u2014T. carbonaria and T. hockingsi\u2014they exhibit a rare\u00a0 duplication of the entire mitogenome and show rapid divergence from other members of their species <a href=\"https:\/\/www.zotero.org\/google-docs\/?yfSvM1\" target=\"_blank\">(Fran\u00e7oso et al., 2023)<\/a>. This accelerated evolution is hypothesized to result from factors such as low effective population, founder effects, and genome duplication triggered by environmental stressors. This phenomenon echoes the earlier work by Conrad H. Waddington (1956) mentioned in this chapter, whose experiments exposing fruit fly embryos to ether induced the development of additional wings and thoraces, changes that later became heritable under stable conditions <a href=\"https:\/\/www.zotero.org\/google-docs\/?FdVXeR\" target=\"_blank\">(Shook et al., 2023b)<\/a>. Both cases highlight how organisms can respond to intense environmental pressures through dramatic developmental and genetic shifts.<\/p>\n<p>The mitochondria genetics influence the energy synthesis of the cells and in most animals, the mitogenome remains relatively stable <a href=\"https:\/\/www.zotero.org\/google-docs\/?Lw5Lmk\" target=\"_blank\">(Shook et al., 2023a)<\/a>; however, Tetragonula species appear to possess an unusual capacity for rapid sequence rearrangement and complete genome duplication, suggesting that their mitogenomes play an important adaptive role. Comparing these genomes with other species such as Lepidotrigona\u2014which shows rearrangements but no duplication\u2014 provides a unique opportunity to examine how different lineages respond to similar ecological pressures. <a href=\"https:\/\/www.zotero.org\/google-docs\/?VxrGpj\" target=\"_blank\">Fran\u00e7oso et al. (2023)<\/a> found that Tetragonula mitogenomes form amphimeric circular structures in which two complete genomes are joined head-to-tail, an extremely rare configuration. These arrangements, including inversions and translocations of gene blocks such as ND6, CytB, ND1, and several rRNA and tRNA genes, are far less common in other bee genera. This pattern supports the idea proposed by <a href=\"https:\/\/www.zotero.org\/google-docs\/?V2eJWI\" target=\"_blank\">Gould &amp; Eldredge (1977)<\/a> that species are fundamentally unstable entities subject to bursts of rapid change in response to environmental pressures, rather than progressing along a single linear pathway. It is important to note that not all species within the genus exhibit the same degree or type of genomic flexibility. While T. carbonaria and T. hockingsi show full mitogenome duplications, the aforementioned Lepidotrigona species show only partial rearrangements despite facing similar environmental conditions. This variation challenges deterministic assumptions that evolution necessarily moves species toward optimal forms. Instead, it illustrates that evolution often involves trial-and-error shifts shaped by constraint, chance, and ecological stress.<\/p>\n<p>Although further research is needed to determine precisely what triggers such rapid genomic events, the evidence demonstrates that mitochondria play an active role in shaping evolutionary pathways. These findings complicate traditional gradualist models and highlight the importance of examining molecular responses to environmental pressures.<\/p>\n<\/div>\n<p>&nbsp;<\/p>\n<p class=\"import-Normal\">There is an important lesson in recognizing that what things do in the present is not a good guide to understanding why they came to exist. Gunpowder was invented for entertainment\u2014only later was it adopted for killing people. The Internet was invented to decentralize computers in case of a nuclear attack\u2014and only later adopted for social media. Apes have short thumbs and use their hands in locomotion; our ancestors stopped using their hands in locomotion by about six million years ago and had fairly modern-looking hands by about two million years ago. We can speculate that a combination of selection for abstract thought and dexterity led to evolution of the human hand, with its capability for toolmaking that exceeds what apes can do (see Figure 3.5). But let\u2019s face it\u2014how many tools have you made today?<\/p>\n<p class=\"import-Normal\">Consequently, we are obliged to see the human foot as having a purpose to which it is adapted and the human hand as having multiple purposes, most of which are different from what it originally evolved for. Paleontologists Gould and Elisabeth Vrba suggested that an original use be regarded as an adaptation and any additional uses be called \u201c<strong>exaptations.<\/strong>\u201d Thus, we would consider the human hand to be an adaptation for toolmaking and an exaptation for writing. So how do we know whether any particular feature is an adaptation, like the walking foot, rather than an exaptation, like the writing hand? Or more broadly, how can we reason rigorously from what a feature does to what it evolved for?<\/p>\n<p class=\"import-Normal\">The answer to the question \u201cwhat did this feature evolve for?\u201d creates an origin myth. This origin myth contains three assumptions: (1) features can be isolated as evolutionary units; (2) there is a specific reason for the existence of any particular feature; and (3) there is a clear and simplistic explanation for why the feature evolved.<\/p>\n<figure style=\"width: 378px\" class=\"wp-caption alignright\"><img src=\"https:\/\/opentextbooks.concordia.ca\/explorations\/wp-content\/uploads\/sites\/57\/2023\/08\/image9-8.png\" alt=\"Head with images and human qualities drawn on it. Journal title printed at the bottom.\" width=\"378\" height=\"437\" \/><figcaption class=\"wp-caption-text\">Figure 3.6: According to the early 19th century science of phrenology, units of personality could be mapped onto units in the head, as shown on this cover of The Phrenology Journal. Credit: <a href=\"https:\/\/wellcomecollection.org\/works\/b6skynug\" target=\"_blank\">Phrenology; Chart<\/a> [slide number 5278, photo number: L0000992, original print from Dr. E. Clark, The Phrenological Journal (Know Thyself)] by <a href=\"https:\/\/wellcomecollection.org\/\" target=\"_blank\">Wellcome Collection<\/a>, is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/legalcode\" target=\"_blank\">CC BY 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">The first assumption was appreciated a century ago as the \u201cunit-character problem.\u201d Are the units by which the body grows and evolves the same as units we name? This is clearly not the case: we have genes and we have noses, and we have genes that affect noses, but we don\u2019t have \u201cnose genes.\u201d What is the relationship between the evolving elements that we see, identify, and name, and the elements that biologically exist and evolve? It is hard to know, but we can use the history of science as a guide to see how that fallacy has been used by earlier generations. Back in the 19th century, the early anatomists argued that since the brain contained the mind, they could map different mental states (acquisitiveness, punctuality, sensitivity) onto parts of the brain. Someone who was very introspective, say, would have an enlarged introspection part of the brain, a cranial bulge to represent the hyperactivity of this mental state. The anatomical science was known as <strong>phrenology<\/strong>, and it was predicated on the false assumption that units of thought or personality or behaviour could be mapped to distinct parts of the brain and physically observed (see Figure 3.6). This is the fallacy of reification, imagining that something named is something real.<\/p>\n<figure style=\"width: 295px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"https:\/\/opentextbooks.concordia.ca\/explorations\/wp-content\/uploads\/sites\/57\/2023\/08\/image1-8-1.png\" alt=\"A black-and-white drawing of a chimpanzee head and face.\" width=\"295\" height=\"236\" \/><figcaption class=\"wp-caption-text\">Figure 3.7: Chimpanzees have big ears. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Chimpanzee_head_sketch.png\" target=\"_blank\">Chimpanzee head sketch<\/a> by <a href=\"https:\/\/de.wikipedia.org\/wiki\/Benutzer:Roger_Zenner\" target=\"_blank\">Roger Zenner<\/a>, original by Brehms Tierleben (1887), is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\" target=\"_blank\">public domain<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">The second assumption, that everything has a reason, has long been recognized as a core belief of religion. Our desire to impose order and simplicity on the workings of the universe, however, does not constrain it to obey simple and orderly causes. Magic, witchcraft, spirits, and divine agency are all powerful explanations for why things happen. Consequently, it is probably not a good idea to lump natural selection in with those. Sometimes things do happen for a reason, of course, but other times things happen as byproducts of other things, or for very complicated and entangled reasons, or for no reason at all. What phenomena have reasons and thereby merit explanation? Chimpanzees have very large testicles, and we think we know why: their promiscuous sexual behaviour triggers intense competition for high sperm count. But chimpanzees also have very large ears, but much less scientific attention has been paid to this trait (see Figure 3.7). Why not? Why should there be a reason for chimp testicles but not for chimp ears? What determines the kinds of features that we try to explain, as opposed to the ones that we do not? Again, the assumption that any specific feature has a reason is metaphysical; that is to say, it may be true in any particular case, but to assume it in all cases is gratuitous.<\/p>\n<p class=\"import-Normal\">And third, the possibility of knowing what the reason for any particular feature is, assuming that it has one, is a challenge for evolutionary epistemology (the theory of how we know things). Consider the big adaptations of our lineage: bipedalism and language. Nobody doubts that they are good, and they evolved by natural selection, and we know how they work. But why did they evolve? If talking and walking are simply better than not talking and not walking, then why did they evolve in just a single branch of the ape lineage in the primate family tree? We don\u2019t know what bipedalism evolved for, although there are plenty of speculations: walking long distances, running long distances, cooling the head, seeing over tall grass, carrying babies, carrying food, wading, threatening, counting calories, sexual display, and so on. Neither do we know what language evolved for, although there are speculations: coordinating hunting, gossiping, manipulating others. But it is also possible that bipedality is simply the way that a small arboreal ape travels on the ground, if it isn\u2019t in the treetops. Or that language is simply the way that a primate with small canine teeth and certain mental propensities comes to communicate. If that were true, then there might be no reason for bipedality or language: having the unique suite of preconditions and a fortuitous set of circumstances simply set them in motion, and natural selection elaborated and explored their potentials. It is possible that walking and talking simply solved problems that no other lineage had ever solved; but even if so, the fact remains that the rest of the species in the history of life have done pretty well without having solved them.<\/p>\n<p class=\"import-Normal\">It is certainly very optimistic to think that all three assumptions (that organisms can be meaningfully atomized, that everything has a reason, and that we can know the reason) would be simultaneously in effect. Indeed, just as there are many ways of adapting (genetically, epigenetically, behaviourally, culturally), there are also many ways of being nonadaptive, which would imply that there is no reason at all for the feature in question.<\/p>\n<p class=\"import-Normal\">First, there is the element of randomness of population histories. There are more cases of sickle-cell anemia among sub-Saharan Africans than other peoples, and there is a reason for it: carriers of sickle-cell anemia have a resistance to malaria, which is more frequent in parts of Africa (as discussed in Chapters 4 and 14). But there are more cases of a blood disease called variegated porphyria, a rare genetic metabolic disorder, in the Afrikaners of South Africa (descendants of mostly Dutch settlers in the 17th century) than in other peoples, and there is no reason for it. Yet we know the cause: One of the founding Dutch colonial settlers had the <strong>allele<\/strong>\u2013a variant of a gene\u2013and everyone in South Africa with it today is her descendant. But that is not a reason\u2014that is simply an accident of history.<\/p>\n<p class=\"import-Normal\">Second, there is the potential mismatch between the past and the present. The value of a particular feature in the past may be changed as the environmental circumstances change. Our species is diurnal, and our ancestors were diurnal. But beginning around a few hundred thousand years ago, our ancestors could build fires, which extended the light period, which was subsequently further amplified by lamps and candles. And over the course of the 20th century, electrical power has made it possible for people to stay up very late when it is dark\u2014working, partying, worrying\u2014to a greater extent than any other closely related species. In other words, we evolved to be diurnal, yet we are now far more nocturnal than any of our recent ancestors or close relatives. Are we adapting to nocturnality? If so, why? Does it even make any sense to speak of the human occupation of a nocturnal ape niche, despite the fact that we empirically seem to be doing just that? And if so, does it make sense to ask what the reason for it is?<\/p>\n<p class=\"import-Normal\">Third, there is a genetic phenomenon known as a selective sweep, or the hitchhiker effect. Imagine three genes\u2014A, B, and C\u2014located very closely together on a chromosome. They each have several variants, or alleles, in the population. Now, for whatever reason, it becomes beneficial to have one of the B alleles, say B4; this B4 allele is now under strong positive selection. Obviously, we will expect future generations to be characterized by mostly B4. But what was B4 attached to? Because whatever A and C alleles were adjacent to it will also be quickly spread, simply by virtue of the selection for B4. Even if the A and C alleles are not very good, they will spread because of the good B4 allele between them. Eventually the linkage groups will break up because of genetic crossing-over in future generations. But in the meantime, some random version of genes A and C are proliferating in the species simply because they are joined to superior allele B4. And clearly, the A and C alleles are there because of selection\u2014but not because of selection <em>for<\/em> them!<\/p>\n<p class=\"import-Normal\">Fourth, some features are simply consequences of other properties rather than adaptations to external conditions. We already noted the phenomenon of allometric growth, in which some physical features have to outgrow others to maintain function at an increased size. Can we ask the reason for the massive brow ridges of <em>Homo erectus<\/em>, or are brow ridges simply what you get when you have a conjunction of thick skull bones, a large face, and a sloping forehead\u2014and, thus, again would have a cause but no reason?<\/p>\n<p class=\"import-Normal\">Fifth, some features may be underutilized and on the way out. What is the reason for our two outer toes? They aren\u2019t propulsive, they don\u2019t do anything, and sometimes they\u2019re just in the way. Obviously they are there because we are descended from ancestors with five digits on their hands and feet. Is it possible that a million years from now, we will just have our three largest toes, just as the ancestors of the horse lost their digits in favour of a single hoof per limb? Or will our outer toes find another use, such as stabilizing the landings in our personal jet-packs? For the time being, we can just recognize vestigiality as another nonadaptive explanation for the presence of a given feature.<\/p>\n<p class=\"import-Normal\">Finally, Darwin himself recognized that many obvious features do not help an animal survive. Some things may instead help an animal breed. The peacock\u2019s tail feathers do not help it eat, but they do help it mate. There is competition, but only against half of the species. Darwin called this <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1084\">sexual selection<\/a><\/strong>. Its result is not a fit to the environment but, rather, a fit to the opposite sex. In some species, that is literally the case, as the male and female genitalia have specific ways of anatomically fitting together. The specific form is less important than the specific match, so inquiring about the reason for a particular form of the reproductive anatomy may be misleading. The specific form may be effectively random, as long as it fits the opposite sex and is different from the anatomies of other species. Nor is sexual selection the only form of selection that can affect the body differently from natural selection. Competition might also take place between biological units other than organisms\u2014perhaps genes, perhaps cells, or populations, or species. The spread of cultural things, such as head-binding or cheap refined fructose or forced labour, can have significant effects upon bodies, which are also not adaptations produced by natural selection. They are often adaptive physiological responses to stresses but not the products of natural selection.<\/p>\n<p class=\"import-Normal\">With so many paths available by which a physical feature might have organically arisen without having been the object of natural selection, it is unwise to assume that any individual trait is an adaptation. And that generalization applies to the best-known, best-studied, and most materially based evolutionary adaptations of our lineage. But our cultural behaviours are also highly adaptive, so what about our most familiar social behaviours? Patriarchy, hierarchy, warfare\u2014are these adaptations? Do they have reasons? Are they good for something?<\/p>\n<p class=\"import-Normal\">This is where some sloppy thinking has been troublesome. What would it mean to say that patriarchy evolved by natural selection in the human species? If, on the one hand, it means that the human mind evolved by natural selection to be able to create and survive in many different kinds of social and political regimes, of which patriarchy is one, then biological anthropologists will readily agree. If, on the other hand, it means that patriarchy evolved by natural selection, that implies that patriarchy is genetically determined (since natural selection is a genetic process) and out-reproduced the alleles for other, more egalitarian, social forms. This in turn would imply that patriarchy is an adaptation and therefore of some beneficial value in the past and has become an ingrained part of human nature today. This would be bad news, say, if you harboured ambitions of dismantling it. Dismantling patriarchy in that case would be to go against nature, a futile gesture. In other words, this latter interpretation would be a naturalistic manifesto for a conservative political platform: don\u2019t try to dismantle the patriarchy, because it is within us, the product of evolution\u2014suck it up and live with it.<\/p>\n<p class=\"import-Normal\">Here, evolution is being used as a political instrument for transforming the human genome into an imaginary glass ceiling against equality. There is thus a convergence between the pseudo-biology of crude <strong>adaptationism <\/strong>(the idea that everything is the product of natural selection) and the pseudo-biology of hereditarianism. Naturalizing inequality is not the business of evolutionary theory, and it represents a difficult moral position for a scientist to adopt, as well as a poor scientific position.<\/p>\n<div class=\"textbox\" style=\"background: var(--lightblue)\">\n<p class=\"import-Normal\"><strong style=\"font-family: &apos;Cormorant Garamond&apos;, serif;font-size: 1.602em\">Evolution of the Anthropocene <\/strong><\/p>\n<figure style=\"width: 379px\" class=\"wp-caption alignright\"><img class=\"\" src=\"https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/8\/8f\/Absetzterseite_des_Tagebaus_Inden_2002.jpg\/500px-Absetzterseite_des_Tagebaus_Inden_2002.jpg\" alt=\"File:Absetzterseite des Tagebaus Inden 2002.jpg\" width=\"379\" height=\"200\" \/><figcaption class=\"wp-caption-text\">Figure 3.8: View of the overburden dumping side of the Inden open-pit lignite mine in the Rhineland, Germany, showing layers of excavated earth used to reconstruct the landscape. Credit: <em data-start=\"249\" data-end=\"289\">Absetzterseite des Tagebaus Inden 2002<\/em> by Rhetos is dedicated to the public domain under the <a href=\"https:\/\/creativecommons.org\/publicdomain\/zero\/1.0\/deed.en\" target=\"_blank\">Creative Commons CC0 1.0 Universal Public Domain Dedication. <\/a><\/figcaption><\/figure>\n<p>Under the previously explored Adaptationism and Panglossian Paradigm, it is explained that human evolution is constantly occurring even throughout periods of ecological stability. While this acknowledges evolution as an ongoing process of change, it fails to explore the implications of such on the alteration of other species and ecosystems.<\/p>\n<p>The emergence of the Anthropocene, driven by human activity, though not recognized as an official epoch, is seen as a transformative event comparable to other major historical shifts such as the Ordovician Biodiversification (UNESCO, 2024). Given its scale, it is crucial to inform scholars about the impact of our social and cultural evolution on the rest of the world. Richard Robbins\u2019 Global Problems and Culture of Capitalism explains how the modern culture of consumption has been extremely successful at accommodating populations of people far larger than previously possible. Robbins claims that the globalization attributed to capitalism has allowed the world to make full use of its environmental resources, providing necessities and innovative technologies to humans all over the world (Robbins &amp; Dowty, 2019). In other words, capitalism is an anthropocentric cultural system that highly benefits humans and facilitates our survival with little regard to the development and survival of other forms of life. It would be highly relevant to introduce the idea that our cultural evolution and capacity to modify the environment to meet our needs have established new environmental conditions in which the human species' survival and reproduction rate expand at the detriment of ecosystems and endangerment of other primates and non-human species.<\/p>\n<p>According to the International Union for Conservation of Nature\u2019s Red List of Threatened Species, there are currently over 169,000 species listed, with more than 47,000 species at risk of extinction \u2014 including 41% of amphibians, 26% of mammals, 26% of freshwater fishes, 12% of birds, and many others (IUCN, 2025). Human lifestyles are causing changes that\u2014if not taken into consideration\u2014could lead to our extinction as a species. The recognition that our evolutionary behavioural development is causing environmental destruction may be the first step for our species to take accountability for the damage that it is causing to others and prevent further damage.<\/p>\n<\/div>\n<\/div>\n<div class=\"__UNKNOWN__\">\n<h2>Cultural Connections and Contemporary Implications<\/h2>\n<p>From an anthropological perspective, the study of genetics and genomics reveals that human evolution is no longer a purely biological process but a deeply cultural one. The Modern Synthesis brings together both Mendelian genetics and population-level evolutionary theory, demonstrating how discrete genes interact across populations through mutation, migration, selection, and drift. Contemporary research in genomics and epigenetics further expands this view, describing how genes are not fixed determinants, but dynamic, responsive systems shaped by environmental, social, and technological forces. This contemporary framework allows anthropology to see human evolution as a continuing dialogue between biology and culture, in which social life and technology now act as powerful forces.<\/p>\n<p>Technological innovation, particularly in the digital age, represents one of these new forces. The human brain is adapting to a world saturated with digital stimuli, shifting to favor pattern recognition and multitasking over deep memorization or spatial awareness. Beyond cognition, the constants of technology's presence in our daily lives\u2014screen exposure, disrupted sleep, and mediated social interaction\u2014can influence neural development and stress-response pathways, blurring the boundaries between biological and cultural adaptation and suggesting that technology itself has become a profound developmental influence.<\/p>\n<p>It is important to note that climate change exerts another global selective pressure, reshaping ecosystems and human responses to them. Physiological adaptation may involve tolerance to heat and fluctuating food sources, while genetic selection could favour metabolic and immune traits suited to new environments. There will also be large changes from a cultural perspective, where migration, innovation, and social restructuring may have large impacts on human evolution.<\/p>\n<p>Genomic engineering further complicates this picture. Techniques such as CRISPR now allow for the precise alteration of DNA, offering immense potential for eliminating hereditary diseases and improving long-term health outcomes. One example is the targeted suppression of the PCSK9 gene to lower LDL cholesterol levels, which can significantly reduce the risk of heart disease in genetically predisposed individuals (Feldscher, 2022). While such interventions hold great promise for preventive medicine, they also raise evolutionary concerns. By artificially narrowing the range of genetic variation, these technologies may weaken the population\u2019s long-term adaptability. Alleles that appear harmful in one context may confer unexpected advantages under different environmental conditions, and their removal could limit evolutionary flexibility. Moreover, as lifespans lengthen and mortality rates decline, population density and resource strain are likely to increase, shifting selective pressures away from disease resistance and toward ecological sustainability and social equilibrium.<\/p>\n<p>While these aspects are important to take into consideration, it remains uncertain how much such current interventions will truly influence long-term human evolution. Many of their effects may occur only at the individual or generational level. Epigenetic modifications, for instance, often fade during gametogenesis, meaning that changes in gene expression caused by lifestyle, stress, or diet may not be inherited. Likewise, the elimination of certain \u201cpoor\u201d genes through technology may occur only in isolated lineages rather than across populations, limiting their evolutionary impact. Nevertheless, anthropology reminds us that even if these changes do not drastically redirect human evolution, they redefine how humans understand and engage with it. The cultural meanings attached to genetic \u201ccorrection,\u201d optimization, and identity echo older anxieties about purity and control. Moreover, the commercialization of genetic data transforms ancestry and kinship into molecular commodities. Whether or not technology reshapes our genes in the long term, it is already reshaping our concept of what it means to be human\u2014a transformation as cultural and philosophical as it is biological.<\/p>\n<h4>Discussion questions<\/h4>\n<ul>\n<li>In what ways has technology shaped humans both culturally and biologically? Can you think of examples from your own lives or society?<\/li>\n<li>Should humans actively intervene in their own evolution through genetic modification? What potential benefits, risks, and social consequences might this create?<\/li>\n<li>How might climate change influence human evolution, both biologically and culturally? What forms of adaptation might become increasingly important as environments change?<\/li>\n<\/ul>\n<div class=\"textbox shaded\">\n<h2 class=\"import-Normal\">Summary<\/h2>\n<p class=\"import-Normal\">Now that you have finished reading this chapter, you are equipped to understand the historical and political dimensions of evolution. Evolution is an ongoing process of change and diversification. Evolutionary theory is a tool that we use to understand this process. The development of evolutionary theory is shaped both by scientific innovation and political engagement. Since Darwin first articulated natural selection as an observable mechanism by which species adapt to their environments, our understanding of evolution has grown. Initially, scientists focused on the adaptive aspects of evolution. However, with the emergence of genetics, our understanding of heredity and the level at which evolution acts has changed. Genetics led to a focus on the molecular dimensions of evolution. For some, this focus resulted in reductive accounts of evolution. Further developments in our understanding of evolution shifted our view to epigenetic processes and how organisms shape their own evolutionary pressures (e.g., niche construction).<\/p>\n<p class=\"import-Normal\">Evolutionary theory will continue to develop in the future as we invent new technologies, describe new dimensions of biology, and experience cultural changes. Current innovations in evolutionary theory are asking us to consider evolutionary forces beyond natural selection and genetics to include the ways organisms shape their environments (niche construction), inheritances beyond genetics (inclusive inheritance), constraints on evolutionary change (developmental bias), and the ability of bodies to change in response to external factors (plasticity). The future of evolutionary theory looks bright as we continue to explore these and other dimensions. Biological anthropology is well-positioned to be a lively part of this conversation, as it extends standard evolutionary theory by considering the role of culture, social learning, and human intentionality in shaping the evolutionary trajectories of humans (Zeder 2018). Remember, at root, human evolutionary theory consists of two propositions: (1) the human species is descended from other similar species and (2) natural selection has been the primary agent of biological adaptation. Pretty much everything else is subject to some degree of contestation.<\/p>\n<h2 class=\"import-Normal\">Review Questions<\/h2>\n<ul>\n<li class=\"import-Normal\">How is the study of your ancestors biopolitical, not just biological? Does that make it less scientific or differently scientific?<\/li>\n<li class=\"import-Normal\">What was gained by reducing organisms to genotypes and species to gene pools? What is gained by reintroducing bodies and species into evolutionary studies?<\/li>\n<li class=\"import-Normal\">How do genetic or molecular studies complement anatomical studies of evolution?<\/li>\n<li class=\"import-Normal\">How are you reducible to your ancestry? If you could meet your ancestors from the year 1700 (and you would have well over a thousand of them!), would their lives be meaningfully similar to yours? Would you even be able to communicate with them?<\/li>\n<li class=\"import-Normal\">The molecular biologist Fran\u00e7ois Jacob argued that evolution is more like a tinkerer than an engineer. In what ways do we seem like precisely engineered machinery, and in what ways do we seem like jerry-rigged or improvised contraptions?<\/li>\n<li class=\"import-Normal\">How might biological anthropology contribute to future developments in evolutionary theory?<\/li>\n<\/ul>\n<\/div>\n<h2 class=\"import-Normal\">Key Terms<strong><br \/>\n<\/strong><\/h2>\n<p class=\"import-Normal\"><strong>Adaptation<\/strong>: A fit between the organism and environment.<\/p>\n<p class=\"import-Normal\"><strong>Adaptationism<\/strong>: The idea that everything is the product of natural selection.<\/p>\n<p class=\"import-Normal\"><strong>Allele<\/strong>: A genetic variant.<\/p>\n<p class=\"import-Normal\"><strong>Allometry<\/strong>: The differential growth of body parts.<\/p>\n<p class=\"import-Normal\"><strong>Canalization<\/strong>: The tendency of a growing organism to be buffered toward normal development.<\/p>\n<p class=\"import-Normal\"><strong>Epigenetics<\/strong>: The study of how genetically identical cells and organisms (with the same DNA base sequence) can nevertheless differ in stably inherited ways.<\/p>\n<p class=\"import-Normal\"><strong>Eugenics<\/strong>: An idea that was popular in the 1920s that society should be improved by breeding \u201cbetter\u201d kinds of people.<\/p>\n<p class=\"import-Normal\"><strong>Evo-devo<\/strong>: The study of the origin of form; a contraction of \u201cevolutionary developmental biology.\u201d<\/p>\n<p class=\"import-Normal\"><strong>Exaptation<\/strong>: An additional beneficial use for a biological feature.<\/p>\n<p class=\"import-Normal\"><strong>Extinction<\/strong>: The loss of a species from the face of the earth.<\/p>\n<p class=\"import-Normal\"><strong>Gene<\/strong>: A stretch of DNA with an identifiable function (sometimes broadened to include any DNA with recognizable structural features as well).<\/p>\n<p class=\"import-Normal\"><strong>Gene pool<\/strong>: Hypothetical summation of the entire genetic composition of population or species.<\/p>\n<p class=\"import-Normal\"><strong>Genotype<\/strong>: Genetic constitution of an individual organism.<\/p>\n<p class=\"import-Normal\"><strong>Hereditarianism<\/strong>: The idea that genes or ancestry is the most crucial or salient element in a human life. Generally associated with an argument for natural inequality on pseudo-genetic grounds.<\/p>\n<p class=\"import-Normal\"><strong>Hox genes<\/strong>: A group of related genes that control for the body plan of an embryo along the head-tail axis.<\/p>\n<p class=\"import-Normal\"><strong>Inheritance of acquired characteristics<\/strong>: The idea that you pass on the features that developed during your lifetime, not just your genes; also known as Lamarckian inheritance.<\/p>\n<p class=\"import-Normal\"><strong>Natural selection<\/strong>: A consistent bias in survival and fertility, leading to the overrepresentation of certain features in future generations and an improved fit between an average member of the population and the environment.<\/p>\n<p class=\"import-Normal\"><strong>Niche construction<\/strong>: The active engagement by which species transform their surroundings in favourable ways, rather than just passively inhabiting them.<\/p>\n<p class=\"import-Normal\"><strong>Phenotype<\/strong>: Observable manifestation of a genetic constitution, expressed in a particular set of circumstances. The suite of traits of an organism.<\/p>\n<p class=\"import-Normal\"><strong>Phrenology<\/strong>: The 19th-century anatomical study of bumps on the head as an indication of personality and mental abilities.<\/p>\n<p class=\"import-Normal\"><strong>Plasticity<\/strong>: The tendency of a growing organism to react developmentally to its particular conditions of life.<\/p>\n<p class=\"import-Normal\"><strong>Punctuated equilibria<\/strong>: The idea that species are stable through time and are formed very rapidly relative to their duration. (The opposite theory, that species are unstable and constantly changing through time, is called phyletic gradualism.)<\/p>\n<p class=\"import-Normal\"><strong>Scientific racism<\/strong>: The use of pseudoscientific evidence to support or legitimize racial hierarchy and inequality.<\/p>\n<p class=\"import-Normal\"><strong>Sexual selection<\/strong>: Natural selection arising through preference by one sex for certain characteristics in individuals of the other sex.<\/p>\n<p class=\"import-Normal\"><strong>Species selection<\/strong>: A postulated evolutionary process in which selection acts on an entire species population, rather than individuals.<\/p>\n<h2 class=\"import-Normal\">For Further Exploration <strong><br \/>\n<\/strong><\/h2>\n<p class=\"import-Normal\">Ackermann, Rebecca Rogers, Alex Mackay, and Michael L. Arnold. 2016. \u201cThe Hybrid Origin of \u2018Modern\u2019 Humans.\u201d <em>Evolutionary Biology<\/em> 43 (1): 1\u201311.<\/p>\n<p class=\"import-Normal\">Bateson, Patrick, and Peter Gluckman. 2011. <em>Plasticity, Robustness, Development and Evolution<\/em>. New York: Cambridge University Press.<\/p>\n<p class=\"import-Normal\">Cosans, Christopher E. 2009. <em>Owen's Ape and Darwin's Bulldog: Beyond Darwinism and Creationism<\/em>. Bloomington, IN: Indiana University Press.<\/p>\n<p class=\"import-Normal\">Desmond, Adrian, and James Moore. 2009. <em>Darwin's Sacred Cause: How a Hatred of Slavery Shaped Darwin's Views on Human Evolution<\/em>. New York: Houghton Mifflin Harcourt.<\/p>\n<p class=\"import-Normal\">Dobzhansky, Theodosius, Francisco J. Ayala, G. Ledyard Stebbins, and James W. Valentine. 1977. <em>Evolution<\/em>. San Francisco: W.H. Freeman and Company.<\/p>\n<p class=\"import-Normal\">Fuentes, Agust\u00edn. 2017. <em>The Creative Spark: How Imagination Made Humans Exceptional<\/em>. New York: Dutton.<\/p>\n<p class=\"import-Normal\">Haraway, Donna J. 1989. <em>Primate Visions: Gender, Race, and Nature in the World of Modern Science<\/em>. New York: Routledge.<\/p>\n<p class=\"import-Normal\">Huxley, Thomas. 1863. <em>Evidence as to Man's Place in Nature<\/em>. London: Williams &amp; Norgate.<\/p>\n<p class=\"import-Normal\">Jablonka, Eva, and Marion J. Lamb. 2005. <em>Evolution in Four Dimensions: Genetic, Epigenetic, Behavioral, and Symbolic Variation in the History of Life<\/em>. Cambridge, MA: The MIT Press.<\/p>\n<p class=\"import-Normal\">Kuklick, Henrika, ed. 2008. <em>A New History of Anthropology<\/em>. New York: Blackwell.<\/p>\n<p class=\"import-Normal\">Laland, Kevin N., Tobias Uller, Marcus W. Feldman, Kim Sterelny, Gerd B. Muller, Armin Moczek, Eva Jablonka, and John Odling-Smee. 2015. \u201cThe Extended Evolutionary Synthesis: Its Structure, Assumptions and Predictions.\u201d <em>Proceedings of the Royal Society, Series B<\/em> 282 (1813): 20151019.<\/p>\n<p class=\"import-Normal\">Lamarck, Jean Baptiste. 1809. <em>Philosophie Zoologique<\/em>. Paris: Dentu.<\/p>\n<p class=\"import-Normal\">Landau, Misia. 1991. <em>Narratives of Human Evolution<\/em>. New Haven: Yale University Press.<\/p>\n<p class=\"import-Normal\">Lee, Sang-Hee. 2017. <em>Close Encounters with Humankind: A Paleoanthropologist Investigates Our Evolving Species<\/em>. New York: W. W. Norton.<\/p>\n<p class=\"import-Normal\">Livingstone, David N. 2008. <em>Adam's Ancestors: Race, Religion, and the Politics of Human Origins<\/em>. Baltimore: Johns Hopkins University Press.<\/p>\n<p class=\"import-Normal\">Marks, Jonathan. 2015. <em>Tales of the Ex-Apes: How We Think about Human Evolution<\/em>. Berkeley, CA: University of California Press.<\/p>\n<p class=\"import-Normal\">Pigliucci, Massimo. 2009. \u201cThe Year in Evolutionary Biology 2009: An Extended Synthesis for Evolutionary Biology.\u201d <em>Annals of the New York Academy of Sciences<\/em> 1168: 218\u2013228.<\/p>\n<p class=\"import-Normal\">Simpson, George Gaylord. 1949. <em>The Meaning of Evolution: A Study of the History of Life and of Its Significance for Man<\/em>. New Haven: Yale University Press.<\/p>\n<p class=\"import-Normal\">Sommer, Marianne. 2016.<em> History Within: The Science, Culture, and Politics of Bones, Organisms, and Molecules<\/em>. Chicago: University of Chicago Press.<\/p>\n<p class=\"import-Normal\">Stoczkowski, Wiktor. 2002. <em>Explaining Human Origins: Myth, Imagination and Conjecture<\/em>. New York: Cambridge University Press.<\/p>\n<p class=\"import-Normal\">Tattersall, Ian, and Rob DeSalle. 2019. <em>The Accidental Homo sapiens: Genetics, Behavior, and Free Will<\/em>. New York: Pegasus.<\/p>\n<h2 class=\"import-Normal\">References<\/h2>\n<p class=\"import-Normal\">Barton, Robert A. 1996. \"Neocortex Size and Behavioural Ecology in Primates.\" <em>Proceedings of the Royal Society of London. Series B: Biological Sciences<\/em> 263 (1367): 173\u2013177.<\/p>\n<p class=\"import-Normal\">Bodmer, Walter, and Robin McKie. 1997. <em>The Book of Man: The Hman Genome Project and the Quest to Discover our Genetic Heritage.<\/em> Oxford University Press.<\/p>\n<p>Brassard, A., Perron-Laplante, J., Lachapelle, \u00c9., Pierrepont, C. de, &amp; P\u00e9loquin, K. (2018). Oversexualization among emerging adults: Preliminary associations with romantic attachment and intimacy. The Canadian Journal of Human Sexuality, 27(3), 235\u2013247. Project Muse.<\/p>\n<p>Carroll, S. B. (2005). Evolution at Two Levels: On Genes and Form. PLoS Biology, 3(7). Public Library of Science. https:\/\/doi.org\/10.1371\/journal.pbio.0030245<\/p>\n<p>Chudek, M., Muthukrishna, M., &amp; Henrich, J. (2015). Cultural evolution. <em>The Handbook of Evolutionary Psychology<\/em>, 1\u201321. https:\/\/doi.org\/10.1002\/9781119125563.evpsych230<\/p>\n<p class=\"import-Normal\">Darwin, Charles. 1859.<em> On the Origin of Species by Means of Natural Selection, or, the Preservation of Favoured Races in the Struggle for Life<\/em>. London: J. Murray.<\/p>\n<p class=\"import-Normal\">Darwin, Charles. 1871. <em>The Descent of Man, and Selection in Relation to Sex.<\/em> London: J. Murray.<\/p>\n<p class=\"import-Normal\">Dawkins, Richard. 1976. <em>The Selfish Gene. <\/em>Oxford University Press.<\/p>\n<p class=\"import-Normal\">Deacon, T. W. 1998. <em>The Symbolic Species: The Co-evolution of Language and the Brain<\/em>. W. W. Norton &amp; Company.<\/p>\n<p class=\"import-Normal\">Eldredge, N., and S. J. Gould. 1972. \"Punctuated Equilibria: An Alternative to Phyletic Gradualism.\" In <em>Models in Paleobiology<\/em>, edited by T. J. Schopf, 82\u2013115. San Francisco: W. H. Freeman.<\/p>\n<p>Feldscher, K. (2022). <em>Using gene editing to fight deadly genetic diseases<\/em>. Harvard T.H. Chan School of Public Health. https:\/\/hsph.harvard.edu\/news\/using-gene-editing-to-fight-deadly-genetic-diseases\/<\/p>\n<p>Fran\u00e7oso, E., Zuntini, A. R., Ricardo, P. C., Santos, P. K. F., de Souza Araujo, N., Silva, J. P. N., Gon\u00e7alves, L. T., Brito, R., Gloag, R., Taylor, B. A., Harpur, B. A., Oldroyd, B. P., Brown, M. J. F., &amp; Arias, M. C. (2023). Rapid evolution, rearrangements and whole mitogenome duplication in the Australian stingless bees Tetragonula (Hymenoptera: Apidae): A steppingstone towards understanding mitochondrial function and evolution. International Journal of Biological Macromolecules, 242. Elsevier. https:\/\/doi.org\/10.1016\/j.ijbiomac.2023.124568<\/p>\n<p class=\"import-Normal\">Gayon, J. (2010). Sexual selection: Another Darwinian process. Comptes Rendus Biologies, 333(2), 134\u2013144. MEDLINE. https:\/\/doi.org\/10.1016\/j.crvi.2009.12.001<\/p>\n<p>Goldman, E. A., &amp; Sterner, K. N. (2023). Environment, Epigenetics, and the Pace of Human Aging. Annual Review of Anthropology, 52, 279\u2013294. Annual Reviews. https:\/\/doi.org\/10.1146\/annurev-anthro-052721-090516<\/p>\n<p>Gould, S. J., &amp; Eldredge, N. (1977). Punctuated Equilibria: The Tempo and Mode of Evolution Reconsidered. Paleobiology, 3(2), 115\u2013151. JSTOR Biological Sciences Collection.<\/p>\n<p class=\"import-Normal\">Gould, Stephen J. 2003.<em> The Structure of Evolutionary Theory<\/em>. Cambridge, MA: Harvard University Press.<\/p>\n<p class=\"import-Normal\">Gould, Stephen J. 1996. <em>Mismeasure of Man<\/em>. New York: WW Norton &amp; Company.<\/p>\n<p class=\"import-Normal\">Gould, Stephen Jay, and Richard C. Lewontin. 1979. \"The Spandrels of San Marco and the Panglossian Paradigm: A Critique of the Adaptationist Programme.\" <em>Proceedings of the Royal Society of London. Series B: Biological Sciences<\/em> 205 (1151): 581\u2013598.<\/p>\n<p class=\"import-Normal\">Haeckel, Ernst. 1868. <em>Nat\u00fcrliche Sch\u00f6pfungsgeschichte<\/em>. Berlin: Reimer.<\/p>\n<p class=\"import-Normal\">Huxley, Thomas Henry. 1863. <em>Evidence as to Man\u2019s Place in Nature. <\/em>London: Williams and Norgate.<\/p>\n<p>IUCN. 2025. <em>The IUCN Red List of Threatened Species<\/em>. Version 2025-1. https:\/\/www.iucnredlist.org. Accessed on 30 July 2025.<\/p>\n<p class=\"import-Normal\">Kaufman, Thomas C., Mark A. Seeger, and Gary Olsen. 1990. \"Molecular and Genetic Organization of the Antennapedia Gene Complex of <em>Drosophila melanogaster<\/em>.\" <em>Advances in Genetics<\/em> 27: 309\u2013362.<\/p>\n<p class=\"import-Normal\">Kellogg, Vernon. 1917. <em>Headquarters Nights<\/em>. Boston: The Atlantic Monthly Press.<\/p>\n<p class=\"import-Normal\">Kevles, Daniel J., and Leroy Hood. 1993. <em>The Code of Codes: Scientific and Social Issues in the Human Genome Project<\/em>. Cambridge, MA: Harvard University Press.<\/p>\n<p class=\"import-Normal\">Lewontin, Richard, Steven Rose, and Leon Kamin. 2017. <em>Not in Our Genes\u202f: Biology, Ideology, and Human Nature<\/em>, 2nd ed. Chicago: Haymarket Books.<\/p>\n<p class=\"import-Normal\">Lloyd, Elisabeth A., and Stephen J. 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MEDLINE. https:\/\/doi.org\/10.1080\/15592294.2023.2260218<\/p>\n<p>Shultz, Susanne, Emma Nelson, and Robin Dunbar. 2012. \"Hominin Cognitive Evolution: Identifying Patterns and Processes in the Fossil and Archaeological Record.\" <em>Philosophical Transactions of the Royal Society B: Biological Sciences<\/em> 367 (1599): 2130\u20132140.<\/p>\n<p>Shook, B., Nelson, K., Braff, L., &amp; Aguilera, K. (2023a). Molecular Biology and Genetics. https:\/\/opentextbooks.concordia.ca\/explorationsversiontwo\/chapter\/3\/<\/p>\n<p>Shook, B., Nelson, K., Braff, L., &amp; Aguilera, K. (2023b). Social and Biopolitical Dimensions of Evolutionary Thinking. https:\/\/opentextbooks.concordia.ca\/explorationsversiontwo\/chapter\/social-and-bi opolitical-dimensions-of-evolutionary-thinking\/<\/p>\n<p class=\"import-Normal\">Spencer, Herbert. 1864. <em>Principles of Biology.<\/em> London: Williams and Norgate.<\/p>\n<p>UNESCO. (2024).<em> The Anthropocene<\/em>. International Union of Geological Sciences. https:\/\/www.iugs.org\/_files\/ugd\/f1fc07_40d1a7ed58de458c9f8f24de5e739663.pdf?index=true<\/p>\n<p>Vicedo, M. (2025). Charlotte Perkins Gilman: A Pragmatist Framework for Constructing a New Humanhood. Journal of the History of the Behavioral Sciences, 61(4), e70041. MEDLINE. https:\/\/doi.org\/10.1002\/jhbs.70041<\/p>\n<p class=\"import-Normal\">Watson, James D. 1990. \"The Human Genome Project: Past, Present, and Future.\" <em>Science<\/em> 248 (4951): 44\u201349.<\/p>\n<p>Wray, G. A. (2007). The evolutionary significance of cis-regulatory mutations. Nature Reviews. Genetics, 8(3), 206\u2013216. MEDLINE.<\/p>\n<p>Waddington CH. Genetic assimilation of the bithorax phenotype. Evolution. 1956;10:1\u201313. doi: 10.1111\/j.1558-5646.1956.tb02824.x.<\/p>\n<p class=\"import-Normal\">Yengo, L., Vedantam, S., Marouli, E., Sidorenko, J., Bartell, E., Sakaue, S., Graff, M., Eliasen, A.U., Jiang, Y., Raghavan, S. and Miao, J., 2022. A saturated map of common genetic variants associated with human height. <em>Nature<\/em>, <em>610 <\/em>(7933): 704-712.<\/p>\n<p class=\"import-Normal\">Zeder, Melinda A. 2018. \"Why Evolutionary Biology Needs Anthropology: Evaluating Core Assumptions of the Extended Evolutionary Synthesis.\" <em>Evolutionary Anthropology: Issues, News, and Reviews<\/em> 27 (6): 267\u2013284.<\/p>\n<\/div>\n<\/div>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1695_1847\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1695_1847\"><div tabindex=\"-1\"><div class=\"__UNKNOWN__\">\n<div class=\"textbox\">\n<h6>Student contributors for this chapter from Salinda Hess' ANTH 203: <em>Emma Costa, Shima Gahima, Will Lefebvre, Audrey Ch\u00e9kina\u00ebl.\u00a0<\/em><\/h6>\n<p>Learn more about <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/about-the-authors\/\">authors and editors<\/a>,<a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/student-contributors\/\"> Hess' student contributions<\/a>, and <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/versioning-history\/\">versioning history<\/a>.<\/p>\n<\/div>\n<\/div>\n<div class=\"__UNKNOWN__\">\n<div class=\"textbox textbox--learning-objectives\">\n<header class=\"textbox__header\">\n<h2 class=\"textbox__title\">Learning Objectives<\/h2>\n<\/header>\n<div class=\"textbox__content\">\n<ul>\n<li class=\"import-Normal\">Explain and identify the purpose of both DNA replication and the cell cycle.<\/li>\n<li class=\"import-Normal\">Identify key differences between mitosis and meiosis.<\/li>\n<li class=\"import-Normal\">Outline the process of protein synthesis, including transcription and translation.<\/li>\n<li class=\"import-Normal\">Use principles of Mendelian inheritance to predict genotypes and phenotypes of future generations.<\/li>\n<li class=\"import-Normal\">Explain complexities surrounding patterns of genetic inheritance and polygenic traits.<\/li>\n<li class=\"import-Normal\">Discuss challenges to and bioethical concerns of genetic testing.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<h2 class=\"import-Normal\">Cells and Molecules<\/h2>\n<h3 class=\"import-Normal\">Molecules of Life<\/h3>\n<p class=\"import-Normal\">All organisms are composed of four basic types of molecules that are essential for cell structure and function: proteins<strong>, <\/strong>lipids<strong>, <\/strong>carbohydrates, and nucleic acids (Figure 4.1). <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_586\">Proteins<\/a> <\/strong>are crucial for cell shape and nearly all cellular tasks, including receiving signals from outside the cell and mobilizing intra-cellular responses. <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_588\">Lipids<\/a> <\/strong>are a class of organic compounds that include fats, oils, and hormones.\u00a0<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_590\">Carbohydrates<\/a><\/strong> are sugar molecules and serve as energy to cells in the form of glucose. Lastly, <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_592\">nucleic acids<\/a><\/strong>, including <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_594\">deoxyribonucleic acid (DNA)<\/a><\/strong>, carry genetic information about a living organism.<\/p>\n<table class=\"aligncenter\" style=\"width: 740px;height: 551px\" border=\"1pt solid rgb(0, 0, 0)\" cellpadding=\"5pt\">\n<caption>Figure 4.1: Information about the four biomolecules. Credit: Biomolecules Table original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Hayley Mann is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/ target=\">CC BY-NC 4.0 License<\/a>.<\/caption>\n<thead>\n<tr style=\"height: 40px\">\n<td class=\"a-C\" style=\"background-color: transparent;padding: 5pt;border: 1pt solid #000000;width: 125.594px;height: 40px\">\n<p class=\"import-Normal\"><strong>Molecule<\/strong><\/p>\n<\/td>\n<td class=\"a-C\" style=\"background-color: transparent;padding: 5pt;border: 1pt solid #000000;width: 223.906px;height: 40px\">\n<p class=\"import-Normal\" style=\"margin-left: 36pt\"><strong>Definition<\/strong><\/p>\n<\/td>\n<td class=\"a-C\" style=\"background-color: transparent;padding: 5pt;border: 1pt solid #000000;width: 346.562px;height: 40px\">\n<p class=\"import-Normal\" style=\"margin-left: 36pt\"><strong>Example<\/strong><\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"a-R\" style=\"height: 194px\">\n<td class=\"a-C\" style=\"background-color: transparent;padding: 5pt;border: 1pt solid #000000;width: 125.594px;height: 194px\">\n<p class=\"import-Normal\">Proteins<\/p>\n<\/td>\n<td class=\"a-C\" style=\"background-color: transparent;padding: 5pt;border: 1pt solid #000000;width: 223.906px;height: 194px\">\n<p class=\"import-Normal\">Composed of one or more long chains of amino acids (i.e., basic units of protein)<\/p>\n<p class=\"import-Normal\">Often folded into complex 3D shapes that relate to function<\/p>\n<p class=\"import-Normal\">Proteins interact with other types of proteins and molecules<\/p>\n<\/td>\n<td class=\"a-C\" style=\"background-color: transparent;padding: 5pt;border: 1pt solid #000000;width: 346.562px;height: 194px\">\n<p class=\"import-Normal\">Proteins come in different categories including structural (e.g., collagen, keratin, lactase, hemoglobin, cell membrane proteins), defense proteins (e.g, antibodies), enzymes (e.g., lactase), hormones (e.g., insulin), and motor proteins (e.g., actin)<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a-R\" style=\"height: 137px\">\n<td class=\"a-C\" style=\"background-color: transparent;padding: 5pt;border: 1pt solid #000000;width: 125.594px;height: 137px\">\n<p class=\"import-Normal\">Lipids<\/p>\n<\/td>\n<td class=\"a-C\" style=\"background-color: transparent;padding: 5pt;border: 1pt solid #000000;width: 223.906px;height: 137px\">\n<p class=\"import-Normal\">Insoluble in water due to hydrophilic (water-loving) head and a hydrophobic (water-repelling) tail<\/p>\n<\/td>\n<td class=\"a-C\" style=\"background-color: transparent;padding: 5pt;border: 1pt solid #000000;width: 346.562px;height: 137px\">\n<p class=\"import-Normal\">Fats, such as triglycerides, store energy for your body<\/p>\n<p class=\"import-Normal\">Steroid hormones (e.g., estrogen and testosterone) act as chemical messengers to communicate between cells and tissues, as well as biochemical pathways inside of the cell<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a-R\" style=\"height: 80px\">\n<td class=\"a-C\" style=\"background-color: transparent;padding: 5pt;border: 1pt solid #000000;width: 125.594px;height: 80px\">\n<p class=\"import-Normal\">Carbohydrates<\/p>\n<\/td>\n<td class=\"a-C\" style=\"background-color: transparent;padding: 5pt;border: 1pt solid #000000;width: 223.906px;height: 80px\">\n<p class=\"import-Normal\">Large group of organic molecules that are composed of carbon and hydrogen atoms<\/p>\n<\/td>\n<td class=\"a-C\" style=\"background-color: transparent;padding: 5pt;border: 1pt solid #000000;width: 346.562px;height: 80px\">\n<p class=\"import-Normal\">Starches and sugars, including blood glucose, provide cells with energy<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a-R\" style=\"height: 78px\">\n<td class=\"a-C\" style=\"background-color: transparent;padding: 5pt;border: 1pt solid #000000;width: 125.594px;height: 78px\">\n<p class=\"import-Normal\">Nucleic Acids<\/p>\n<\/td>\n<td class=\"a-C\" style=\"background-color: transparent;padding: 5pt;border: 1pt solid #000000;width: 223.906px;height: 78px\">\n<p class=\"import-Normal\">Carries the genetic information of an organism<\/p>\n<\/td>\n<td class=\"a-C\" style=\"background-color: transparent;padding: 5pt;border: 1pt solid #000000;width: 346.562px;height: 78px\">\n<p class=\"import-Normal\">DNA<\/p>\n<p class=\"import-Normal\">RNA<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h3 class=\"import-Normal\">Cells<\/h3>\n<p class=\"import-Normal\">In 1665, Robert Hooke observed slices of plant cork using a microscope. Hooke noted that the microscopic plant structures he saw resembled <em>cella,<\/em> meaning \u201ca small room\u201d in Latin. Approximately two centuries later, biologists recognized the cell as being the most fundamental unit of life and that all life is composed of cells. Cellular organisms can be characterized as two main cell types: <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_596\">prokaryotes<\/a><\/strong> and <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_598\">eukaryotes<\/a> <\/strong>(Figure 4.2).<\/p>\n<figure id=\"attachment_77\" aria-describedby=\"caption-attachment-77\" style=\"width: 468px\" class=\"wp-caption alignleft\"><a href=\"\/explorationsclone\/part\/figure-3-2\/\" target=\"_blank\" rel=\"noopener\"><img class=\"wp-image-70\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2023\/06\/cellsfinal-scaled-1.jpg\" alt=\"Prokaryote and eukaryote cells. A full text description of this image is available using link in the caption.\" width=\"468\" height=\"370\" \/><\/a><figcaption id=\"caption-attachment-77\" class=\"wp-caption-text\">Figure 4.2: Prokaryotic cell and eukaryotic cell. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available.<\/a> Credit: Prokaryote vs. eukaryote original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Mary Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Prokaryotes include bacteria and archaea, and they are composed of a single cell. Additionally, their DNA and <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_600\">organelles<\/a><\/strong> are not surrounded by individual membranes. Thus, no compartments separate their DNA from the rest of the cell (see Figure 4.2). It is well known that some bacteria can cause illness in humans. For instance, <em>Escherichia coli<\/em> (<em>E. coli<\/em>) and <em>Salmonella<\/em> contamination can result in food poisoning symptoms. Pneumonia and strep throat are caused by <em>Streptococcal<\/em> bacteria. <em>Neisseria gonorrhoeae<\/em> is a sexually transmitted bacterial disease. Although bacteria are commonly associated with illness, not all bacteria are harmful. For example, researchers are studying the relationship between the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_602\">microbiome<\/a> <\/strong>and human health. The bacteria that are part of the healthy human microbiome perform beneficial roles, such as digesting food, boosting the immune system, and even making vitamins (e.g., B12 and K).<\/p>\n<p class=\"import-Normal\">Eukaryotes can be single-celled or multi-celled in their body composition. In contrast to prokaryotes, eukaryotes possess membranes that surround their DNA and organelles. An example of a single-celled eukaryote is the microscopic algae found in ponds (phytoplankton), which can produce oxygen from the sun. Yeasts are also single-celled, and fungi can be single- or multicellular. Plants and animals are all multicellular.<\/p>\n<p class=\"import-Normal\">Although plant and animal cells have a surprising number of similarities, there are some key differences (Figure 4.3). For example, plant cells possess a thick outer cell membrane made of a fibrous carbohydrate called cellulose. Animal and plant cells also have different <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_604\">tissues<\/a><\/strong>. For most plants, the outermost layer of cells forms a waxy cuticle that helps to protect the cells and to prevent water loss. Humans have skin, which is the outermost cell layer that is predominantly composed of a tough protein called keratin. Overall, humans have a diversity of tissue types (e.g., cartilage, brain, and heart).<\/p>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_77-2\" aria-describedby=\"caption-attachment-77-2\" style=\"width: 2560px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-71 size-full\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/3.x3ai-01-scaled-1.jpg\" alt=\"Plant and animal cells. A full text description of this image is available using link in the caption.\" width=\"2560\" height=\"1162\" \/><figcaption id=\"caption-attachment-77-2\" class=\"wp-caption-text\">Figure 4.3: Plant cell compared to an animal cell. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available.<\/a> Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Simple_plant_and_animal_cell.svg\" target=\"_blank\">Simple plant and animal cell<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Nefronus\" target=\"_blank\">Tom\u00e1\u0161 Kebert<\/a> &amp; <a href=\"https:\/\/www.umimeto.org\/\" target=\"_blank\">umimeto.org<\/a> has been modified (labels added) and is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\" target=\"_blank\">CC BY-NC-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<h3 class=\"import-Normal\"><strong>Animal Cell Organelles<\/strong><\/h3>\n<p class=\"import-Normal\">An animal cell is surrounded by a double membrane called the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_606\">phospholipid bilayer<\/a> <\/strong>(Figure 4.4). A closer look reveals that this protective barrier is made of lipids and proteins that provide structure and function for cellular activities, such as regulating the passage of molecules and ions (e.g., H<sub>2<\/sub>O and sodium) into and out of the cell. <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_608\">Cytoplasm<\/a><\/strong> is the jelly-like matrix inside of the cell membrane. Part of the cytoplasm comprises organelles, which perform different specialized tasks for the cell (Figure 4.5). An example of an organelle is the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_610\">nucleus<\/a><\/strong>, where the cell\u2019s DNA is located.<\/p>\n<p>&nbsp;<\/p>\n<figure style=\"width: 555px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image1.png\" alt=\"Cell wall of a phospholipid bilayer with embedded channels, carbohydrates, and proteins.\" width=\"555\" height=\"270\" \/><figcaption class=\"wp-caption-text\">Figure 4.4: A phospholipid bilayer with membrane-bound carbohydrates and proteins. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available.<\/a> Credit: <a href=\"https:\/\/openstax.org\/books\/anatomy-and-physiology\/pages\/3-1-the-cell-membrane#fig-ch03_01_03\" target=\"_blank\">Cell Membrane (Anatomy &amp; Physiology, Figure 3.4)<\/a> by<a href=\"https:\/\/openstax.org\/\"> OpenStax<\/a> is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\" target=\"_blank\"> CC BY 4.0 License<\/a>.<\/figcaption><\/figure>\n<figure style=\"width: 547px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image1-1.png\" alt=\"Animal cell with various organelles labeled.\" width=\"547\" height=\"415\" \/><figcaption class=\"wp-caption-text\">Figure 4.5: An animal cell with membrane-enclosed organelles. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available.<\/a> Credit: <a href=\"https:\/\/www.genome.gov\/genetics-glossary\/Organelle?id=147\" target=\"_blank\">Organelle<\/a> by<a href=\"https:\/\/www.genome.gov\/\" target=\"_blank\"> NIH National Human Genome Research Institute<\/a> is in the<a href=\"https:\/\/www.genome.gov\/about-nhgri\/Policies-Guidance\/Copyright\" target=\"_blank\"> public domain<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Another organelle is the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_612\">mitochondrion<\/a><\/strong>. Mitochondria are often referred to as \u201cpowerhouse centers\u201d because they produce energy for the cell in the form of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_616\">adenosine triphosphate (ATP)<\/a><\/strong>. Depending on the species and tissue type, multicellular eukaryotes can have hundreds to thousands of mitochondria in each of their cells. Scientists have determined that mitochondria were once <em>symbiotic<\/em> prokaryotic organisms (i.e., helpful bacteria) that transformed into cellular organelles over time. This evolutionary explanation helps explain why mitochondria also have their own DNA, called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_618\">mitochondrial DNA (mtDNA)<\/a><\/strong>. All organelles have important physiological functions and disease can occur when organelles do not perform their role optimally. Figure 4.6 lists other organelles found in the cell and their specialized cellular roles.<\/p>\n<table class=\"aligncenter\" style=\"width: 399pt\" border=\"1pt solid rgb(0, 0, 0)\" cellpadding=\"5pt\">\n<caption>Figure 4.6: This table depicts the names of organelles and their cellular functions. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-9\/\" target=\"_blank\">Cell Structure table (Figure 3.11)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Hayley Mann, Xazmin Lowman, and Malaina Gaddis is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/caption>\n<thead>\n<tr>\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Cell structure<\/strong><\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Description<\/strong><\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"a0-R\" style=\"height: 36pt\">\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Centrioles<\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Assist with the organization of mitotic spindles, which extend and contract for the purpose of cellular movement during mitosis and meiosis.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a0-R\" style=\"height: 36pt\">\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Cytoplasm<\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Gelatinous fluid located inside of cell membrane that contains organelles.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a0-R\" style=\"height: 24pt\">\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Endoplasmic reticulum (ER)<\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Continuous membrane with the nucleus that helps transport, synthesize, modify, and fold proteins. Rough ER has embedded ribosomes, whereas smooth ER lacks ribosomes.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a0-R\" style=\"height: 24pt\">\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Golgi body<\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Layers of flattened sacs that receive and transmit messages from the ER to secrete and transport proteins within the cell.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a0-R\" style=\"height: 24pt\">\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Lysosome<\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Located in the cytoplasm; contains enzymes to degrade cellular components.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a0-R\" style=\"height: 24pt\">\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Microtubule<\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Involved with cellular movement including intracellular transport and cell division.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a0-R\" style=\"height: 24pt\">\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Mitochondrion<\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Responsible for cellular respiration, where energy is produced by converting nutrients into ATP.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a0-R\" style=\"height: 24pt\">\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Nucleolus<\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Resides inside of the nucleus and is the site of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_620\">ribosomal RNA (rRNA)<\/a><\/strong> transcription, processing, and assembly.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a0-R\" style=\"height: 24pt\">\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Nucleopore<\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Pores in the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_622\">nuclear envelope<\/a><\/strong> that are selectively permeable.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a0-R\">\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Nucleus<\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Contains the cell\u2019s DNA and is surrounded by the nuclear envelope.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a0-R\">\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Ribosome<\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Located in the cytoplasm and also the membrane of the rough endoplasmic reticulum. Messenger RNA (mRNA) binds to ribosomes and proteins are synthesized.<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h2 class=\"import-Normal\">Introduction to Genetics<\/h2>\n<p class=\"import-Normal\">Genetics is the study of heredity. Biological parents pass down their genetic traits to their offspring. Although children resemble their parents, genetic traits often vary in appearance or molecular function. For example, two parents with normal color vision can sometimes produce a son with red-green colorblindness. <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_624\">Molecular geneticists<\/a> <\/strong>study the biological mechanisms responsible for creating variation between individuals, such as DNA <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_626\">mutations<\/a><\/strong> (see Chapter 5), cell division, and genetic regulation.<\/p>\n<p class=\"import-Normal\"><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_628\">Molecular anthropologists<\/a><\/strong> use genetic data to test anthropological questions. Some of these anthropologists utilize <strong>ancient DNA (aDNA)<\/strong>, which is DNA that is extracted from anything once living, including human, animal, and plant remains. Over time, DNA becomes degraded (i.e., less intact), but specialized laboratory techniques can make copies of short degraded aDNA segments, which can then be reassembled to provide more complete DNA information.<\/p>\n<h3 class=\"import-Normal\"><strong>DNA Structure<\/strong><\/h3>\n<p class=\"import-Normal\">The discovery, in 1953, of the molecular structure of deoxyribonucleic acid (DNA) was one of the greatest scientific achievements of all time. Using X-ray crystallography, Rosalind Franklin (Figure 4.7) provided an image that clearly showed the double helix shape of DNA. Due to controversy, Franklin\u2019s colleagues received more recognition for the DNA discovery. In 1962, Watson, Crick, and Wilkins won the Nobel Prize, while Franklin, who had died in 1958, was not honoured. Today, her vital contributions and scientific skill are widely recognized.<\/p>\n<figure style=\"width: 223px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image2-1.png\" alt=\"Historic photo of woman looking into a microscope.\" width=\"223\" height=\"268\" \/><figcaption class=\"wp-caption-text\">Figure 4.7: Chemist and X-ray crystallographer Rosalind Franklin. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Rosalind_Franklin.jpg\" target=\"_blank\">Rosalind Franklin<\/a> from the personal collection of Jenifer Glynn by MRC Laboratory of Molecular Biology is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\" target=\"_blank\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">The double helix shape of DNA can be described as a twisted ladder (Figure 4.8). More specifically, DNA is a double-stranded molecule with its two strands oriented in opposite directions (i.e., antiparallel). Each strand is composed of <strong>nucleotides <\/strong>with a<strong> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_634\">sugar phosphate backbone<\/a><\/strong>. There are four different types of DNA nucleotides: adenine (A), thymine (T), cytosine (C), and guanine (G). The two DNA strands are held together by nucleotide <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_636\">base pairs<\/a><\/strong>, which have chemical bonding rules. The complementary base-pairing rules are as follows: A and T bond with each other, while C and G form a bond. The chemical bonds between A-T and C-G are formed by \u201cweak\u201d hydrogen atom interactions, which means the two strands can be easily separated. A DNA sequence is the order of nucleotide bases (A, T, G, C) along only one DNA strand. If one DNA strand has the sequence CATGCT, then the other strand will have a complementary sequence GTACGA. This is an example of a short DNA sequence. In reality, there are approximately three billion DNA base pairs in human cells.<\/p>\n<figure style=\"width: 341px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image3.jpg\" alt=\"Double helix structure of DNA.\" width=\"341\" height=\"400\" \/><figcaption class=\"wp-caption-text\">Figure 4.8: Structural components that form double-stranded nucleic acid (DNA). Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Difference_DNA_RNA-EN.svg\" target=\"_blank\">Difference DNA RNA-EN<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Sponk\" target=\"_blank\">Sponk<\/a> (translation by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Sponk\" target=\"_blank\">Sponk<\/a>, cropped by Katie Nelson) is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\" target=\"_blank\">CC BY-NC-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<h3 class=\"import-Normal\"><strong>DNA Is Highly Organized within the Nucleus<\/strong><\/h3>\n<p class=\"import-Normal\">If you removed the DNA from a single human cell and stretched it out completely, it would measure approximately two meters (about 6.5 feet). Therefore, DNA molecules must be compactly organized in the nucleus. To achieve this, the double helix configuration of DNA undergoes coiling. An analogy would be twisting a string until coils are formed and then continuing to twist so that secondary coils are formed, and so on. To assist with coiling, DNA is first wrapped around proteins called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_638\">histones<\/a><\/strong>. This creates a complex called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_640\">chromatin<\/a>,<\/strong> which resembles \u201cbeads on a string\u201d (Figure 4.9). Next, chromatin is further coiled into a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_642\">chromosome<\/a><\/strong>. Another important feature of DNA is that chromosomes can be altered from tightly coiled (chromatin) to loosely coiled (<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_644\">euchromatin<\/a><\/strong>). Most of the time, chromosomes in the nucleus remain in a euchromatin state so that DNA sequences are accessible for regulatory processes to occur.<\/p>\n<p>&nbsp;<\/p>\n<figure style=\"width: 558px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image1-2.png\" alt=\"Illustrates how chromosomes are made up of various components. \" width=\"558\" height=\"534\" \/><figcaption class=\"wp-caption-text\">Figure 4.9: The hierarchical organization of chromosomes. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available<\/a>.\u00a0Credit: <a href=\"https:\/\/www.genome.gov\/glossary\/index.cfm?id=102\" target=\"_blank\">Histone (2019)<\/a> by<a href=\"https:\/\/www.genome.gov\/\" target=\"_blank\"> NIH National Human Genome Research Institute<\/a> is in the<a href=\"https:\/\/www.genome.gov\/about-nhgri\/Policies-Guidance\/Copyright\" target=\"_blank\"> public domain<\/a>.<\/figcaption><\/figure>\n<figure style=\"width: 256px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image4-1.png\" alt=\"Chromatid is divided into a short and long arm, bound by a centromere. \" width=\"256\" height=\"296\" \/><figcaption class=\"wp-caption-text\">Figure 4.10: The regions of a chromosome. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-9\/\" target=\"_blank\">Chromosome (Figure 3.16)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Katie Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<\/div>\n<p>&nbsp;<\/p>\n<div class=\"__UNKNOWN__\">\n<p>Human body cells typically have 23 pairs of chromosomes, for a total of 46 chromosomes in each cell\u2019s nucleus. An interesting fact is that the number of chromosomes an organism possesses varies by species, and this figure is not dependent upon the size or complexity of the organism. For instance, chimpanzees have a total of 48 chromosomes, while hermit crabs have 254. Chromosomes also have a distinct physical structure, including <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_646\">centromeres<\/a> <\/strong>(the \u201ccenter\u201d) and <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_648\">telomeres<\/a> <\/strong>(the ends) (Figure 4.10). Because of the centromeric region, chromosomes are described as having two different \u201carms,\u201d where one arm is long and the other is shorter. Centromeres play an important role during cell division, which will be discussed in the next section. Telomeres are located at the ends of chromosomes; they help protect the chromosomes from degradation after every round of cell division.<\/p>\n<\/div>\n<p>&nbsp;<\/p>\n<div class=\"__UNKNOWN__\">\n<div class=\"textbox\">\n<h2 class=\"import-Normal\">Special Topic: First Nation Immunity and European Diseases\u2014A Study of Ancient DNA<\/h2>\n<figure style=\"width: 300px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image5-1.png\" alt=\"A group of people in historic clothing, some with traditional shawls, eat under a tent.\" width=\"300\" height=\"184\" \/><figcaption class=\"wp-caption-text\">Figure 4.11a: Tsimshian Native Americans of the Pacific Northwest Coast. Credit: <a href=\"https:\/\/central.bac-lac.gc.ca\/.redirect?app=fonandcol&amp;id=3368729&amp;lang=eng\" target=\"_blank\">A group of Tsimshian people having a tea party in a tent, Lax Kw'alaams (formerly Port Simpson), B.C., c. 1890<\/a> by unknown photographer is in the <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/pdm\" target=\"_blank\">Public Domain<\/a>. This image is available from the <a href=\"https:\/\/www.bac-lac.gc.ca\/eng\/Pages\/home.aspx\" target=\"_blank\">Library and Archives Canada<\/a>, item number 3368729.<\/figcaption><\/figure>\n<p>Beginning in the early fifteenth century, First Nations progressively suffered from high mortality rates as the result of colonization from foreign powers. European-borne diseases such as measles, tuberculosis, influenza, and smallpox are largely responsible for the population collapse of Indigenous peoples in the Americas. Many Europeans who immigrated to the Americas had lived in large sedentary populations, which also included coexisting with domestic animals and pests. Although a few prehistoric Indigenous populations can be characterized as large agricultural societies (especially in Mesoamerica), their overall culture, community lifestyle, and subsistence practices were markedly different from that of Europeans. Therefore, because they did not share the same urban living environments as Europeans, it is believed that Indigenous peoples were susceptible to many European diseases.<\/p>\n<figure style=\"width: 459px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image6.jpg\" alt=\"Tsimshian territory on the coast of British Columbia next to the Hecate Strait.\" width=\"459\" height=\"594\" \/><figcaption class=\"wp-caption-text\">Figure 4.11b: Tsimshian territory in present-day British Columbia. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-9\/\" target=\"_blank\">Tsimshian Territory map (Figure 3.12b)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Elyssa Ebding at<a href=\"https:\/\/www.csuchico.edu\/geop\/geoplace\/index.shtml\" target=\"_blank\"> GeoPlace, California State University, Chico<\/a> is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\"> CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p>In 2016, a <em>Nature<\/em> article published by John Lindo and colleagues was the first to investigate whether pre-contact Indigenous peoples possessed a genetic susceptibility to European diseases. Their study included Tsimshians, a First Nation community from British Columbia (Figure 4.11a-b). DNA from both present-day and ancient individuals (who lived between 500 and 6,000 years ago) was analysed. The research team discovered that a change occurred in the <em>HLA-DQA1<\/em> gene, which is a member of the major histocompatibility complex (MHC) immune system molecules. MHC molecules are responsible for detecting and triggering an immune response against pathogens. Lindo and colleagues (2016) concluded that <em>HLA-DQA1<\/em> gene helped Indigenous peoples adapt to their local environmental ecology. However, when European-borne epidemics occurred in the Northwest during the 1800s, a certain <em>HLA-DQA1<\/em> <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_650\">DNA sequence<\/a><\/strong> variant (allele) associated with ancient Tsimshian immunity was no longer adaptive. As the result of past selective pressures from European diseases, present-day Tsimshians have different <em>HLA-DQA1<\/em> allele frequencies. The precise role that <em>HLA-DQA1 <\/em>plays in immune adaptation requires further investigation. But overall, this study serves as an example of how studying ancient DNA from the remains of deceased individuals can help provide insight into living human populations and historical events.<\/p>\n<\/div>\n<h2 class=\"import-Normal\">DNA Replication and Cell Division<\/h2>\n<p class=\"import-Normal\">For life to continue and flourish, cells must be able to divide. Tissue growth and cellular damage repair are also necessary to maintain an organism throughout its life. All these rely on the dynamic processes of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_652\">DNA replication<\/a><\/strong> and the <strong>cell cycle<\/strong>. The mechanisms highlighted in this section are tightly regulated and represent only part of the life cycle of a cell.<\/p>\n<h3 class=\"import-Normal\"><strong>DNA Replication <\/strong><\/h3>\n<p class=\"import-Normal\">DNA replication is the process by which new DNA is copied from an original DNA template. It is one phase of the highly coordinated cell cycle, and it requires a variety of enzymes with special functions. The creation of a complementary DNA strand from a template strand is described as <strong>semi-conservative replication<\/strong>. The result of semi-conservative replication is two separate double-stranded DNA molecules, each of which is composed of an original \u201cparent\u201d template strand and a newly synthesized \u201cdaughter\u201d DNA strand.<\/p>\n<p class=\"import-Normal\">DNA replication progresses in three steps referred to as <strong>initiation<\/strong>, <strong>elongation,<\/strong> and <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_662\">termination<\/a><\/strong>. During initiation, enzymes are recruited to specific sites along the DNA sequence (Figure 4.12). For example, an initiator enzyme, called <strong>helicase<\/strong>, \u201cunwinds\u201d DNA by breaking the hydrogen bonds between the two parent strands. The unraveling of the helix into two separated strands exposes the strands and creates a fork, which is the active site of DNA replication.<\/p>\n<figure style=\"width: 580px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image7.jpg\" alt=\"Helicase enzyme splits apart 2 DNA strands. On each strand DNA polymerase matches free nucleotides.\" width=\"580\" height=\"359\" \/><figcaption class=\"wp-caption-text\">Figure 4.12: DNA replication and the different enzymes associated with it. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available<\/a>. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:0323_DNA_Replication.jpg\" target=\"_blank\">0323 DNA Replication<\/a> by <a href=\"https:\/\/openstax.org\/books\/anatomy-and-physiology\/pages\/1-introduction\" target=\"_blank\">OpenStax<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/legalcode\" target=\"_blank\">CC BY 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Elongation is the assembly of new DNA daughter strands from the exposed original parent strands. The two parent strands can further be classified as <strong>leading strand<\/strong> or <strong>lagging strand<\/strong> and are distinguished by the direction of replication. Enzymes called <strong>DNA polymerases<\/strong> read parent template strands in a specific direction. Complementary nucleotides are added, and the newly formed daughter strands will grow. On the leading parent strand, a DNA polymerase will create one continuous strand. The lagging parent strand is created in several disconnected sections and other enzymes fill in the missing nucleotide gaps between these sections.<\/p>\n<p class=\"import-Normal\">Finally, termination refers to the end of DNA replication activity. It is signaled by a stop sequence in the DNA that is recognized by machinery at the replication fork. The end result of DNA replication is that the number of chromosomes are doubled so that the cell can divide into two.<\/p>\n<h3 class=\"import-Normal\"><strong>DNA Mutations<\/strong><\/h3>\n<p class=\"import-Normal\">DNA replication should result in the creation of two identical DNA nucleotide sequences. However, although DNA polymerases are quite precise during DNA replication, copying mistakes are estimated to occur every 10<sup>7<\/sup> DNA nucleotides. Variation from the original DNA sequence is known as a mutation (Refer to Chapter 5). Briefly, mutations can result in single-nucleotide changes, as well as the insertion or deletion of nucleotides and repeated sequences. Depending on where they occur in the genome, mutations can be <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_672\">deleterious<\/a> <\/strong>(harmful). For example, mutations may occur in regions that control cell cycle regulation, which can result in cancer (see Special Topic: The Cell Cycle and Immortality of Cancer Cells). Many other types of mutations, however, are not harmful to an organism.<\/p>\n<p class=\"import-Normal\">Regardless of their effect, the cell attempts to reduce the frequency of mutations that occur during DNA replication. To accomplish this, there are polymerases with proofreading capacities that can identify and correct mismatched nucleotides. These safeguards reduce the frequency of DNA mutations so that they only occur every 10<sup>9<\/sup> nucleotides.<\/p>\n<h3 class=\"import-Normal\"><strong>Mitotic Cell Division<\/strong><\/h3>\n<p class=\"import-Normal\">There are two types of cells in the body: <strong>germ cells <\/strong>(sperm and egg) and <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_676\">somatic cells<\/a><\/strong>. The body and its various tissues comprises somatic cells. Organisms that contain two sets of chromosomes in their somatic cells are called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_678\">diploid<\/a><\/strong> organisms. Humans have 46 chromosomes and they are diploid because they inherit one set of chromosomes (<em>n <\/em>= 23) from each parent. As a result, they have 23 matching pairs of chromosomes, which are known as <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_680\">homologous chromosomes<\/a><\/strong>. As seen in Figure 4.13, homologous chromosome pairs vary in size and are generally numbered from largest (chromosome 1) to smallest (chromosome 22) with the exception of the 23rd pair, which is made up of the sex chromosomes (X and Y). Typically, the female sex is XX and the male sex is XY. Individuals inherit an X chromosome from their chromosomal mother and an X or Y from their chromosomal father.<\/p>\n<figure id=\"attachment_81\" aria-describedby=\"caption-attachment-81\" style=\"width: 468px\" class=\"wp-caption alignleft\"><img class=\"wp-image-81\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/Karyotype.jpg\" alt=\"Karyotype showing pairs of chromosomes organized by size into 23 pairs.\" width=\"468\" height=\"263\" \/><figcaption id=\"caption-attachment-81\" class=\"wp-caption-text\">Figure 4.13: The 23 human chromosome pairs. Credit: Genome (2019) by NIH National Human Genome Research Institute is in the public domain.<\/figcaption><\/figure>\n<p class=\"import-Normal\">To grow and repair tissues, somatic cells must divide. As discussed previously, for cell division to occur, a cell must first replicate its genetic material. During DNA replication, each chromosome produces double the amount of genetic information. The duplicated arms of chromosomes are known as <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_682\">sister chromatids<\/a>,<\/strong> and they are attached at the centromeric region. To elaborate, the number of chromosomes stays the same (<em>n<\/em> = 46); however, the amount of genetic material is doubled in the cell as the result of replication.<\/p>\n<p class=\"import-Normal\"><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_684\">Mitosis<\/a><\/strong> is the process of somatic cell division that gives rise to two diploid daughter cells (Figure 4.14). Once DNA and other organelles in the cell have finished replication, mitotic spindle fibres physically align each chromosome at the center of the cell. Next, the spindle fibres divide the sister chromatids and move each one to opposite sides of the cell. At this phase, there are 46 chromosomes on each side of a human cell. The cell can now divide into two fully separated daughter cells.<\/p>\n<\/div>\n<figure id=\"attachment_88\" aria-describedby=\"caption-attachment-88\" style=\"width: 569px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-82\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/mitosismeiosisNEW.jpg\" alt=\"The stages of mitosis and meiosis.\" width=\"569\" height=\"521\" \/><figcaption id=\"caption-attachment-88\" class=\"wp-caption-text\">Figure 4.14: The steps of mitotic cell division and meiotic cell division. Credit: Mitosis and meiosis original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Katie Nelson is a collective work under a CC BY-NC 4.0 License. [Includes Mitosis (Figure 3.20) and Meiosis (Figure 3.21) by Mary Nelson; CC BY-NC 4.0 License.]<\/figcaption><\/figure>\n<div class=\"__UNKNOWN__\">\n<h3 class=\"import-Normal\"><strong>Meiotic Cell Division<\/strong><\/h3>\n<p class=\"import-Normal\">Gametogenesis is the production of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_686\">gametes<\/a><\/strong> (sperm and egg cells); it involves two rounds of cell division called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_688\">meiosis<\/a><\/strong>. Similar to mitosis, the parent cell in meiosis is diploid. However, meiosis has a few key differences, including the number of daughter cells produced (four cells, which require two rounds of cell division to produce) and the number of chromosomes each daughter cell has (see Figure 4.14).<\/p>\n<p class=\"import-Normal\">During the first round of division (known as meiosis I), each chromosome (<em>n<\/em> = 46) replicates its DNA so that sister chromatids are formed. Next, with the help of spindle fibres, homologous chromosomes align near the center of the cell and sister chromatids physically swap genetic material. In other words, the sister chromatids of matching chromosomes cross over with each other at matching DNA nucleotide positions. The occurrence of homologous chromosomes crossing over, swapping DNA, and then rejoining segments is called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_690\">genetic recombination<\/a><\/strong>. The \u201cgenetic shuffling\u201d that occurs in gametes increases organismal genetic diversity by creating new combinations of genes on chromosomes that are different from the parent cell. Genetic mutations can also arise during recombination. For example, there may be an unequal swapping of genetic material that occurs between the two sister chromatids, which can result in deletions or duplications of DNA nucleotides. Once genetic recombination is complete, homologous chromosomes are separated and two daughter cells are formed.<\/p>\n<p class=\"import-Normal\">The daughter cells after the first round of meiosis are <strong>haploid<\/strong>, meaning they only have one set of chromosomes (<em>n <\/em>= 23). During the second round of cell division (known as meiosis II), sister chromatids are separated and two additional haploid daughter cells are formed. Therefore, the four resulting daughter cells have one set of chromosomes (<em>n<\/em> = 23), and they also have a genetic composition that is not identical to the parent cells nor to each other.<\/p>\n<p class=\"import-Normal\">Although both sperm and egg gamete production undergo meiosis, they differ in the final number of viable daughter cells. In the case of spermatogenesis, four mature sperm cells are produced. Although four egg cells are also produced in oogenesis, only one of these egg cells will result in an ovum (mature egg). During fertilization, an egg cell and sperm cell fuse, which creates a diploid cell that develops into an embryo. The ovum also provides the cellular organelles necessary for embryonic cell division. This includes mitochondria, which is why humans, and most other multicellular eukaryotes, have the same mtDNA sequence as their mothers.<\/p>\n<h3 class=\"import-Normal\"><strong>Chromosomal Disorders: Aneuploidies<\/strong><\/h3>\n<p class=\"import-Normal\">During mitosis or meiosis, entire deletions or duplications of chromosomes can occur due to error. For example, homologous chromosomes may fail to separate properly, so one daughter cell may end up with an extra chromosome while the other daughter cell has one less. Cells with an unexpected (or abnormal) number of chromosomes are known as <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_694\">aneuploid<\/a><\/strong>. Adult or embryonic cells can be tested for chromosome number (<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_696\">karyotyping<\/a><\/strong>). Aneuploid cells are typically detrimental to a dividing cell or developing embryo, which can lead to a loss of pregnancy. However, the occurrence of individuals being born with three copies of the 21st chromosome is relatively common; this genetic condition is known as Down Syndrome. Moreover, individuals can also be born with aneuploid sex chromosome conditions such as XXY, XXX, and XO (referring to only one X chromosome).<\/p>\n<div class=\"textbox\">\n<h2 class=\"import-Normal\">Special Topic: The Cell Cycle and Immortality of Cancer Cells<\/h2>\n<p class=\"import-Normal\">DNA replication is part of a series of preparatory phases that a cell undergoes prior to cell division, collectively known as <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_698\">interphase<\/a> <\/strong>(Figure 4.15). During interphase, the cell not only doubles its chromosomes through DNA replication, but it also increases its metabolic capacity to provide energy for growth and division. Transition into each phase of the cell cycle is tightly controlled by proteins that serve as checkpoints. If a cell fails to pass a checkpoint, then DNA replication and\/or cell division will not continue. Some of the reasons why a cell may fail at a checkpoint is DNA damage, lack of nutrients to continue the process, or insufficient size. In turn, a cell may undergo <strong>apoptosis<\/strong>, which is a mechanism for cell death.<\/p>\n<figure style=\"width: 617px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image11.png\" alt=\"The cell cycle is mostly cell growth and DNA synthesis (interphase), followed by the mitotic phase (mitosis and cytokinesis).\" width=\"617\" height=\"433\" \/><figcaption class=\"wp-caption-text\">Figure 4.15: The phases and checkpoints of the cell cycle. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available.<\/a> Credit: <a href=\"https:\/\/cnx.org\/contents\/jVCgr5SL@15.43:SeU_rWbd@14\/10-2-The-Cell-Cycle\" target=\"_blank\">Cell cycle (Biology 2e, Figure 10.5)<\/a> by<a href=\"https:\/\/openstax.org\/\" target=\"_blank\"> OpenStax<\/a> is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\" target=\"_blank\"> CC BY 4.0 License<\/a>.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p class=\"import-Normal\">Unchecked cellular growth is a distinguishing hallmark of cancer. In other words, as cancer cells grow and proliferate, they acquire the capacity to avoid death and replicate indefinitely. This uncontrolled and continuous cell division is also known as \u201cimmortality.\u201d As previously mentioned, most cells lose the ability to divide due to shortening of telomeres on the ends of chromosomes over time. One way in which cancer cells retain replicative immortality is that the length of their telomeres is continuously protected. Chemotherapy, often used to treat cancer, targets the cell cycle (especially cell division) to halt the propagation of genetically abnormal cells. Another therapeutic approach that continues to be investigated is targeting telomere activity to stop the division of cancer cells.<\/p>\n<figure style=\"width: 296px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image12-1.png\" alt=\"Microscope image of irregularly shaped cells with bright nuclei.\" width=\"296\" height=\"223\" \/><figcaption class=\"wp-caption-text\">Figure 4.16: A microscopic slide of HeLa cancer cells. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:HeLa-III.jpg\" target=\"_blank\">HeLa-III<\/a> by National Institutes of Health (NIH) is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\" target=\"_blank\">public domain<\/a>.<\/figcaption><\/figure>\n<p>Researchers have exploited the immortality of cancer cells for molecular research. The oldest immortal cell line is HeLa cells (Figure 4.16), which were harvested from Henrietta Lacks, an African American woman diagnosed with cervical cancer in 1955. At that time, extracted cells frequently died during experiments, but surprisingly HeLa cells continued to replicate. Propagation of Lacks\u2019s cell line has significantly contributed to medical research, including contributing to ongoing cancer research and helping to test the polio vaccine in the 1950s. However, Lacks had not given her consent for her tumor biopsy to be used in cell culture research. Moreover, her family was unaware of the extraction and remarkable application of her cells for two decades. The history of HeLa cell origin was first revealed in 1976. The controversy voiced by the Lacks family was included in an extensive account of HeLa cells published in Rebecca Skloot\u2019s 2010 book, <em>The Immortal Life of Henrietta Lacks<\/em>. A film based on the book was also released in 2017 (Wolfe 2017).<\/p>\n<\/div>\n<h2 class=\"import-Normal\"><span style=\"text-align: initial;font-size: 1em\">Protein Synthesis<\/span><\/h2>\n<p class=\"import-Normal\">At the beginning of the chapter, we defined <em>proteins<\/em> as strings of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_702\">amino acids<\/a><\/strong> that fold into complex 3-D shapes. There are 20 standard amino acids that can be strung together in different combinations in humans, and the result is that proteins can perform an impressive amount of different functions. For instance, muscle fibres are proteins that help facilitate movement. A special class of proteins (immunoglobulins) help protect the organism by detecting disease-causing pathogens in the body. Protein hormones, such as insulin, help regulate physiological activity. Blood hemoglobin is a protein that transports oxygen throughout the body. <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_704\">Enzymes<\/a> <\/strong>are also proteins, and they are catalysts for biochemical reactions that occur in the cell (e.g., metabolism). Larger-scale protein structures can be visibly seen as physical features of an organism (e.g., hair and nails).<\/p>\n<h3 class=\"import-Normal\"><strong>Transcription and Translation <\/strong><\/h3>\n<figure style=\"width: 272px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image13.jpg\" alt=\"From DNA, transcription creates pre-mRNA, is processed to mature mRNA, translated to an amino acid chain (protein)\" width=\"272\" height=\"336\" \/><figcaption class=\"wp-caption-text\">Figure 4.17: The major steps of protein synthesis. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available.<\/a> Credit: Protein synthesis original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Mary Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p>Nucleotides in our DNA provide the coding instructions on how to make proteins. Making proteins, also known as <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_706\">protein synthesis<\/a><\/strong>, can be broken down into two main steps referred to as <strong>transcription<\/strong> and <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_710\">translation<\/a><\/strong>. The purpose of transcription, the first step, is to make an <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_712\">ribonucleic acid (RNA)<\/a><\/strong> copy of our genetic code. Although there are many different types of RNA molecules that have a variety of functions within the cell, we will mainly focus on <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_714\">messenger RNA (mRNA)<\/a><\/strong>.\u00a0Transcription concludes with the processing (<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_716\">splicing<\/a><\/strong>) of the mRNA. The second step, translation, uses mRNA as the instructions for chaining together amino acids into a new protein molecule (Figure 4.17).<\/p>\n<figure style=\"width: 340px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image14.jpg\" alt=\"Single stranded RNA is composed of 4 types of nucleobases: cytosine, guanine, adenine, and uracil.\" width=\"340\" height=\"461\" \/><figcaption class=\"wp-caption-text\">Figure 4.18: Structural components that form ribonucleic acid (RNA). <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available.<\/a> Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Difference_DNA_RNA-EN.svg\" target=\"_blank\">Difference DNA RNA-EN<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Sponk\" target=\"_blank\">Sponk<\/a> (translation by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Sponk\" target=\"_blank\">Sponk<\/a>, cropped by Katie Nelson) is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\" target=\"_blank\">CC BY-NC-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Unlike double-stranded DNA, RNA molecules are single-stranded nucleotide sequences (Figure 4.18). Additionally, while DNA contains the nucleotide thymine (T), RNA does not\u2014instead its fourth nucleotide is uracil (U). Uracil is complementary to (or can pair with) adenine (A), while cytosine (C) and guanine (G) continue to be complementary to each other.<\/p>\n<p>For transcription to proceed, a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_718\">gene<\/a><\/strong> must first be turned \u201con\u201d by the cell. A gene is a segment of DNA that codes for RNA, and genes can vary in length from a few hundred to as many as two million base pairs in length. The double-stranded DNA is then separated, and one side of the DNA is used as a coding template that is read by <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_720\">RNA polymerase<\/a>.<\/strong> Next, complementary free-floating RNA nucleotides are linked together (Figure 4.19) to form a single-stranded mRNA. For example, if a DNA template is TACGGATGC, then the newly constructed mRNA sequence will be AUGCCUACG.<\/p>\n<p>Genes contain segments called <strong>introns <\/strong>and <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_724\">exons<\/a><\/strong>. Exons are considered \u201ccoding\u201d while introns are considered \u201cnoncoding\u201d\u2014meaning the information they contain will not be needed to construct proteins. When a gene is first transcribed into pre-mRNA, introns and exons are both included (Figure 4.20). However, once transcription is finished, introns are removed in a process called splicing. During splicing, a protein\/RNA complex attaches itself to the pre-mRNA. Next, introns are removed and the remaining exons are connected, thus creating a shorter mature mRNA that serves as a template for building proteins.<\/p>\n<figure style=\"width: 1846px\" class=\"wp-caption alignnone\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image15.jpg\" alt=\"DNA strands pulled apart making space for RNA polymerase to form mRNA using 1 DNA template strand.\" width=\"1846\" height=\"473\" \/><figcaption class=\"wp-caption-text\">Figure 4.19: RNA polymerase catalyzing DNA transcription. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available.<\/a> Credit: <a href=\"https:\/\/www.genome.gov\/glossary\/index.cfm?id=197\" target=\"_blank\">Transcription (2019)<\/a>\u00a0by<a href=\"https:\/\/www.genome.gov\/\" target=\"_blank\"> NIH National Human Genome Research Institute<\/a> has been modified (cropped and labels changed by Katie Nelson) and is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<\/div>\n<figure id=\"attachment_88-2\" aria-describedby=\"caption-attachment-88-2\" style=\"width: 1900px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-88 size-full\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/4.20.jpg\" alt=\"Pre mRNA contains transcriptions of exons and introns. Mature mRNA only contains spliced exon mRNA.\" width=\"1900\" height=\"700\" \/><figcaption id=\"caption-attachment-88-2\" class=\"wp-caption-text\">Figure 4.20: RNA processing is the modification of RNA, including the removal of introns, called splicing, between transcription and translation. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available.<\/a> Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-9\/\" target=\"_blank\">Protein synthesis (Figure 3.23)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<div class=\"__UNKNOWN__\">\n<p class=\"import-Normal\">As described above, the result of transcription is a single-stranded mRNA copy of a gene<strong>. <\/strong>Translation is the process by which amino acids are chained together to form a new protein. During translation, the mature mRNA is transported outside of the nucleus, where it is bound to a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_726\">ribosome<\/a> <\/strong>(Figure 4.21). The nucleotides in the mRNA are read in triplets, which are called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_728\">codons<\/a><\/strong>. Each mRNA codon corresponds to an amino acid, which is carried to the ribosome by a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_730\">transfer RNA<\/a> <\/strong>(tRNA). Thus, tRNAs is the link between the mRNA molecule and the growing amino acid chain.<\/p>\n<figure style=\"width: 651px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image17.jpg\" alt=\"Ribosome and tRNA read mRNA and help join amino acids to a growing polypeptide chain.\" width=\"651\" height=\"366\" \/><figcaption class=\"wp-caption-text\">Figure 4.21: Translation of mRNA into a polypeptide chain composed of the twenty different types of amino acids. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available.<\/a> Credit: <a href=\"https:\/\/www.genome.gov\/genetics-glossary\/Amino-Acids?id=5\" target=\"_blank\">Amino Acids<\/a> by<a href=\"https:\/\/www.genome.gov\/\" target=\"_blank\"> NIH National Human Genome Research Institute<\/a> is in the<a href=\"https:\/\/www.genome.gov\/about-nhgri\/Policies-Guidance\/Copyright\" target=\"_blank\"> public domain<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Continuing with our mRNA sequence example from above, the mRNA sequence AUG-CCU-ACG codes for three amino acids. Using a codon table (Figure 4.22), AUG is a codon for methionine (Met), CCU is proline (Pro), and ACG is threonine (Thr). Therefore, the protein sequence is Met-Pro-Thr. Methionine is the most common \u201cstart codon\u201d (AUG) for the initiation of protein translation in eukaryotes. As the ribosome moves along the mRNA, the growing amino acid chain exits the ribosome and folds into a protein. When the ribosome reaches a \u201cstop\u201d codon (UAA, UAG, or UGA), the ribosome stops adding any new amino acids, detaches from the mRNA, and the protein is released. Depending upon the amino acid sequence, a linear protein may undergo additional \u201cfolding.\u201d The final three-dimensional protein shape is integral to completing a specific structural or functional task.<\/p>\n<div class=\"textbox shaded\">\n<h2 class=\"import-Normal\">Dig Deeper: Protein Synthesis<\/h2>\n<p class=\"import-Normal\">To see protein synthesis in animation, please check out the\u00a0 <a href=\"https:\/\/www.yourgenome.org\/video\/from-dna-to-protein\/\" target=\"_blank\">From DNA to Protein<\/a> video on YourGenome.org.<\/p>\n<\/div>\n<figure style=\"width: 550px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image18-1.png\" alt=\"A circle labeled with letters for mRNA nucleotides.\" width=\"550\" height=\"541\" \/><figcaption class=\"wp-caption-text\">Figure 4.22: This table can be used to identify which mRNA codons (sequence of three nucleotides) correspond with each of the 20 different amino acids. For each mRNA codon, you work in the 5\u2019 to 3\u2019 direction (inside the circle to outside). For example, if the mRNA codon is CAU, you look at the inner circle for the \u201cC,\u201d the middle circle for \u201cA,\u201d and outside circle for \u201cU,\u201d indicating that the CAU codon corresponds with the amino acid \u201chistidine\u201d (abbreviated \u201cHis\u201d or \u201cH\u201d). The table also indicates that the \u201cstart codon\u201d (AUG) correlates with Methionine, and the three \u201cstop\u201d codons are UAA, UAG, and UGA. <a href=\"https:\/\/docs.google.com\/document\/d\/1AKB8mx6Ih-V-1DJ_zxTbf9Jn4puHRCPEhG1rGOlojNc\/edit?usp=sharing\" target=\"_blank\" rel=\"noopener\">An accessible full text RNA codon to amino acid table is available.<\/a> Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Aminoacids_table.svg\" target=\"_blank\">Aminoacids table<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Mouagip\" target=\"_blank\">Mouagip<\/a> has been designated to the <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/cc0\/\" target=\"_blank\">public domain (CC0)<\/a>.<\/figcaption><\/figure>\n<h2 class=\"import-Normal\">Mendelian Genetics<\/h2>\n<figure style=\"width: 183px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image19.png\" alt=\"Stone statue of a robed monk.\" width=\"183\" height=\"239\" \/><figcaption class=\"wp-caption-text\">Figure 4.23: Statue of Mendel located at the Mendel Museum, located at Masaryk University in Brno, Czech Republic. Credit: \u00a0<a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Mendel%C2%B4s_statue.JPG\" target=\"_blank\">Mendel\u00b4s statue<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Coeli\" target=\"_blank\">Coeli<\/a> has been designated to the <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/cc0\/\" target=\"_blank\">public domain (CC0)<\/a>.<\/figcaption><\/figure>\n<p>Gregor Johann Mendel (1822\u20131884) is often described as the \u201cFather of Genetics.\u201d Mendel was a monk who conducted pea plant breeding experiments in a monastery located in the present-day Czech Republic (Figure 4.23). After several years of experiments, Mendel presented his work to a local scientific community in 1865 and published his findings the following year. Although his meticulous effort was notable, the importance of his work was not recognized for another 35 years. One reason for this delay in recognition is that his findings did not agree with the predominant scientific viewpoints on inheritance at the time. For example, it was believed that parental physical traits \u201cblended\u201d together and offspring inherited an intermediate form of that trait. In contrast, Mendel showed that certain pea plant physical traits (e.g., flower color) were passed down separately to the next generation in a statistically predictable manner. Mendel also observed that some parental traits disappeared in offspring but then reappeared in later generations. He explained this occurrence by introducing the concept of \u201cdominant\u201d and \u201crecessive\u201d traits. Mendel established a few fundamental laws of inheritance, and this section reviews some of these concepts. Moreover, the study of traits and diseases that are controlled by a single gene is commonly referred to as <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_732\">Mendelian genetics<\/a><\/strong>.<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<figure style=\"width: 738px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image20.png\" alt=\"Pea plant variation: round\/wrinkled, yellow\/ green pods, white\/purple flowers, tall\/short stem.\" width=\"738\" height=\"304\" \/><figcaption class=\"wp-caption-text\">Figure 4.24: Various phenotypic characteristics of pea plants resulting from different genotypes. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Mendels_peas.png\" target=\"_blank\">Mendels peas<\/a> by Mariana Ruiz <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:LadyofHats\" target=\"_blank\">LadyofHats<\/a> has been designated to the <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/cc0\/\" target=\"_blank\">public domain (CC0 1.0)<\/a>.<\/figcaption><\/figure>\n<p>The physical appearance of a trait is called an organism\u2019s <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_734\">phenotype<\/a><\/strong>. Figure 4.24 shows pea plant (<em>Pisum sativum<\/em>) phenotypes that were studied by Mendel, and in each of these cases the physical traits are controlled by a single gene. In the case of Mendelian genetics, a phenotype is determined by an organism\u2019s <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_736\">genotype<\/a><\/strong>. A genotype consists of two gene copies, wherein one copy was inherited from each parent. Gene copies are also known as <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_738\">alleles<\/a><\/strong> (Figure 4.25), which means they are found in the same gene location on homologous chromosomes. Alleles have a nonidentical DNA sequence, which means their phenotypic effect can be different. In other words, although alleles code for the same trait, different phenotypes can be produced depending on which two alleles (i.e., genotypes) an organism possesses. For example, Mendel\u2019s pea plants all have flowers, but their flower color can be purple or white. Flower color is therefore dependent upon which two color alleles are present in a genotype.<\/p>\n<figure style=\"width: 771px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image21.jpeg\" alt=\"Four pairs of chromosomes. Each chromosome is labeled with an allele, either capital B or lowercase b.\" width=\"771\" height=\"315\" \/><figcaption class=\"wp-caption-text\">Figure 4.25: Homozygous refers to having the same alleles (e.g. two capital Bs or two lowercase bs). Heterozygous refers to having two different alleles (e.g. one capital B and one lowercase b). Credit: <a href=\"https:\/\/www.genome.gov\/genetics-glossary\/homozygous\" target=\"_blank\">Homozygous<\/a> by<a href=\"https:\/\/www.genome.gov\/\" target=\"_blank\"> NIH National Human Genome Research Institute<\/a> is in the<a href=\"https:\/\/www.genome.gov\/about-nhgri\/Policies-Guidance\/Copyright\" target=\"_blank\"> public domain<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">A Punnett square is a diagram that can help visualize Mendelian inheritance patterns. For instance, when parents of known genotypes mate, a Punnett square can help predict the ratio of Mendelian genotypes and phenotypes that their offspring would possess. When discussing genotype, biologists use upper and lower case letters to denote the different allele copies. Figure 4.26 is a Punnett square that includes two <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_740\">heterozygous<\/a><\/strong> parents for flower color (Bb). A heterozygous genotype means there are two different alleles for the same gene. Therefore, a pea plant that is heterozygous for flower color has one purple allele and one white allele. When an organism is <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_742\">homozygous<\/a><\/strong> for a specific trait, it means their genotype consists of two copies of the same allele. Using the Punnett square example, the two heterozygous pea plant parents can produce offspring with two different homozygous genotypes (BB or bb) or offspring that are heterozygous (Bb).<\/p>\n<figure style=\"width: 220px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image22.png\" alt=\"Pollen and Pistol (each with one capital B and one lower case b allele) merge in different combinations.\" width=\"220\" height=\"220\" \/><figcaption class=\"wp-caption-text\">Figure 4.26: Punnett square depicting the possible genetic combinations of offspring from two heterozygous parents. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available.<\/a> Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Punnett_square_mendel_flowers.svg\" target=\"_blank\">Punnett square mendel flowers<\/a> by Madeleine Price Ball (<a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Madprime\" target=\"_blank\">Madprime<\/a>) is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">A pea plant with purple flowers could be heterozygous (Bb) or homozygous (BB). This is because the purple color allele (B) is <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_744\">dominant<\/a> <\/strong>to the white color allele (b), and therefore it only needs one copy of that allele to phenotypically express purple flowers. Because the white flower allele is <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_746\">recessive<\/a><\/strong>, a pea plant must be homozygous for the recessive allele in order to have a white color phenotype (bb). As seen by the Punnett square example (Figure 4.26), three of four offspring will have purple flowers and the other one will have white flowers.<\/p>\n<p class=\"import-Normal\">The Law of Segregation was introduced by Mendel to explain why we can predict the ratio of genotypes and phenotypes in offspring. As discussed previously, a parent will have two alleles for a certain gene (with each copy on a different homologous chromosome). The Law of Segregation states that the two copies will be segregated from each other and will each be distributed to their own gamete. We now know that the process where that occurs is meiosis.<\/p>\n<p class=\"import-Normal\">Offspring are the products of two gametes combining, which means the offspring inherits one allele from each gamete for most genes. When multiple offspring are produced (like with pea plant breeding), the predicted phenotype ratios are more clearly observed. The pea plants Mendel studied provide a simplistic model to understand single-gene genetics. While many traits anthropologists are interested in have a more complicated inheritance (e.g., are informed by many genes), there are a few known Mendelian traits in humans. Additionally, some human diseases also follow a Mendelian pattern of inheritance (Figure 4.27). Because humans do not have as many offspring as other organisms, we may not recognize Mendelian patterns as easily. However, understanding these principles and being able to calculate the probability that an offspring will have a Mendelian phenotype is still important.<\/p>\n<\/div>\n<div align=\"left\">\n<table class=\"grid aligncenter\" style=\"width: 422px;height: 420px\">\n<caption>Figure 4.27: Examples of human diseases with their gene names that follow a Mendelian pattern of inheritance.<\/caption>\n<thead>\n<tr style=\"height: 30px\">\n<td style=\"width: 432.598px;height: 30px\"><strong>Mendelian disorder<\/strong><\/td>\n<td style=\"width: 89.9414px;height: 30px\"><strong>Gene\u00a0<\/strong><\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr style=\"height: 30px\">\n<td style=\"width: 432.598px;height: 30px\">Alpha Thalassemia<\/td>\n<td style=\"width: 89.9414px;height: 30px\">HBA1<\/td>\n<\/tr>\n<tr style=\"height: 30px\">\n<td style=\"width: 432.598px;height: 30px\">Cystic Fibrosis<\/td>\n<td style=\"width: 89.9414px;height: 30px\">CFTR<\/td>\n<\/tr>\n<tr style=\"height: 30px\">\n<td style=\"width: 432.598px;height: 30px\">Fragile X Syndrome<\/td>\n<td style=\"width: 89.9414px;height: 30px\">FMR1<\/td>\n<\/tr>\n<tr style=\"height: 30px\">\n<td style=\"width: 432.598px;height: 30px\">Glucose-6-Phosphate Dehydrogenase Deficiency<\/td>\n<td style=\"width: 89.9414px;height: 30px\">G6PD<\/td>\n<\/tr>\n<tr style=\"height: 30px\">\n<td style=\"width: 432.598px;height: 30px\">Hemophilia A<\/td>\n<td style=\"width: 89.9414px;height: 30px\">F8<\/td>\n<\/tr>\n<tr style=\"height: 30px\">\n<td style=\"width: 432.598px;height: 30px\">Huntington disease<\/td>\n<td style=\"width: 89.9414px;height: 30px\">HTT<\/td>\n<\/tr>\n<tr style=\"height: 30px\">\n<td style=\"width: 432.598px;height: 30px\">Mitochondrial DNA Depletion Syndrome<\/td>\n<td style=\"width: 89.9414px;height: 30px\">TYMP<\/td>\n<\/tr>\n<tr style=\"height: 30px\">\n<td style=\"width: 432.598px;height: 30px\">Oculocutaneous Albinism: Type 1<\/td>\n<td style=\"width: 89.9414px;height: 30px\">TYR<\/td>\n<\/tr>\n<tr style=\"height: 30px\">\n<td style=\"width: 432.598px;height: 30px\">Polycystic Kidney Disease<\/td>\n<td style=\"width: 89.9414px;height: 30px\">PKHD1<\/td>\n<\/tr>\n<tr style=\"height: 30px\">\n<td style=\"width: 432.598px;height: 30px\">Sickle-cell anemia<\/td>\n<td style=\"width: 89.9414px;height: 30px\">HBB<\/td>\n<\/tr>\n<tr style=\"height: 30px\">\n<td style=\"width: 432.598px;height: 30px\">Spinal Muscular Atrophy: SMN1 Linked<\/td>\n<td style=\"width: 89.9414px;height: 30px\">SMN1<\/td>\n<\/tr>\n<tr style=\"height: 30px\">\n<td style=\"width: 432.598px;height: 30px\">Tay-Sachs Disease<\/td>\n<td style=\"width: 89.9414px;height: 30px\">HEXA<\/td>\n<\/tr>\n<tr style=\"height: 30px\">\n<td style=\"width: 432.598px;height: 30px\">Wilson Disease<\/td>\n<td style=\"width: 89.9414px;height: 30px\">ATP7B<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div class=\"__UNKNOWN__\">\n<h3 class=\"import-Normal\"><strong>Example of Mendelian Inheritance: The ABO Blood Group System<\/strong><\/h3>\n<p class=\"import-Normal\">In 1901, Karl Landsteiner at the University of Vienna published his discovery of ABO blood groups. While conducting blood immunology experiments in which he combined the blood of individuals who possess different blood cell types, he observed an agglutination (clotting) reaction. The presence of agglutination implies there is an incompatible immunological reaction; no agglutination will occur in individuals with the same blood type. This work was clearly important because it resulted in a higher survival rate of patients who received blood transfusions. Blood transfusions from someone with a different type of blood causes agglutinations, and the resulting coagulated blood can not easily pass through blood vessels, resulting in death. Landsteiner received the Nobel Prize (1930) for his discovery and explaination of the ABO blood group system.<\/p>\n<p class=\"import-Normal\">Blood <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_748\">cell surface antigens<\/a><\/strong> are proteins that coat the surface of red blood cells, and<strong> antibodies <\/strong>are specifically \u201cagainst\u201d or \u201canti\u201d to the antigens from other blood types. Thus, antibodies are responsible for causing agglutination between incompatible blood types. Understanding the interaction of antigens and antibodies helps to determine ABO compatibility amongst blood donors and recipients. Individuals that are blood type A have A antigens on the red blood cell surface, and anti-B antibodies, which will bind to B antigens should they come in contact. Alternatively, individuals with blood type B have B antigens and anti-A antibodies. Individuals with blood type AB have both A and B antigens but do not produce antibodies for the ABO system. This does not mean type AB does not have any antibodies present, just that specifically anti-A and anti-B antibodies are not produced. Individuals who are blood type O have nonspecific antigens and produce both anti-A and anti-B antibodies.<\/p>\n<p class=\"import-Normal\">Figure 4.28 shows a table of the ABO allele system, which has a Mendelian pattern of inheritance. Both the A and B alleles function as dominant alleles, so the A allele always codes for the A antigen, and the B allele codes for the B antigen. The O allele differs from A and B, because it codes for a nonfunctional antigen protein, which means there is no antigen present on the cell surface of O blood cells. To have blood type O, two copies of the O allele must be inherited, one from each parent, thus the O allele is considered recessive. Therefore, someone who is a heterozygous AO genotype is phenotypically blood type A, and a genotype of BO is blood type B. The ABO blood system also provides an example of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_752\">codominance<\/a><\/strong>, which is when both alleles are observed in the phenotype. This is true for blood type AB: when an individual inherits both the A and B alleles, then both A and B antigens will be present on the cell surface.<\/p>\n<figure style=\"width: 425px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image24.jpg\" alt=\"A table showing the genotypes that can occur from combinations of A, B, and O alleles.\" width=\"425\" height=\"177\" \/><figcaption class=\"wp-caption-text\">Figure 4.28: The different combinations of ABO blood alleles (A, B, and O) to form ABO blood genotypes. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available<\/a>. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-9\/\" target=\"_blank\">ABO Blood Genotypes (Figure 3.33)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Katie Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Also found on the surface of red blood cells is the rhesus group antigen, known as \u201cRh factor.\u201d In reality, there are several antigens on red blood cells independent from the ABO blood system, however, the Rh factor is the second most important antigen to consider when determining blood donor and recipient compatibility. Rh antigens must also be considered when a pregnant mother and her baby have incompatible Rh factors. In such cases, a doctor can administer necessary treatment steps to prevent pregnancy complications and hemolytic disease, which is when the mother\u2019s antibodies break down the newborn\u2019s red blood cells.<\/p>\n<p class=\"import-Normal\">An individual can possess the Rh antigen (be Rh positive) or lack the Rh antigen (be Rh negative). The Rh factor is controlled by a single gene and is inherited independently of the ABO alleles. Therefore, all blood types can either be positive (O+, A+, B+, AB+) or negative (O-, A-, B-, AB-).<\/p>\n<p class=\"import-Normal\">Individuals with O+ red blood cells can donate blood to A+, B+, AB+, and O+ blood type recipients. Because O- individuals do not have AB or Rh antigens, they are compatible with all blood cell types and are referred to as \u201cuniversal donors.\u201d Individuals that are AB+ are considered to be \u201cuniversal recipients\u201d because they do not possess antibodies against other blood types.<\/p>\n<h3 class=\"import-Normal\"><strong>Mendelian Patterns of Inheritance and Pedigrees<\/strong><\/h3>\n<p class=\"import-Normal\">A <strong>pedigree<\/strong> can be used to investigate a family\u2019s medical history by determining if a health issue is inheritable and will possibly require medical intervention. A pedigree can also help determine if it is a Mendelian recessive or dominant genetic condition. Figure 4.29 is a pedigree example of a family with Huntington\u2019s disease, which has a Mendelian dominant pattern of inheritance. In a standard pedigree, males are represented by a square and females are represented by a circle. Biological family members are connected to a horizontal line, with biological parents above and offspring below. When an individual is affected with a certain condition, the square or circle is filled in as a solid color. With a dominant condition, at least one of the parents will have the disease and an offspring will have a 50% chance of inheriting the affected chromosome. Therefore, dominant genetic conditions tend to be present in every generation. In the case of Huntington\u2019s, some individuals may not be diagnosed until later in adulthood, so parents may unknowingly pass this dominantly inherited disease to their children.<\/p>\n<figure style=\"width: 389px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image25.png\" alt=\"A three-generation pedigree with about half the individuals shaded in. Please see text discussion for details.\" width=\"389\" height=\"189\" \/><figcaption class=\"wp-caption-text\">Figure 4.29: A pedigree depicting an example of dominant Mendelian inheritance like Huntington\u2019s. Offspring with the trait will have at least one parent with the same trait. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-9\/\" target=\"_blank\">Mendelian dominant pattern of inheritance (Figure 3.34)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Beth Shook is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Because the probability of inheriting a disease-causing recessive allele is more rare, recessive medical conditions can skip generations. Figure 4.30 is an example of a family that carries a recessive cystic fibrosis mutation. A parent that is heterozygous for the cystic fibrosis allele has a 50% chance of passing down their affected chromosome to the next generation. If a child has a recessive disease, then it means both of their parents are <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_756\">carriers<\/a><\/strong> (heterozygous) for that condition. In most cases, carriers for recessive conditions show no serious medical symptoms. Individuals whose family have a known medical history for certain conditions sometimes seek family planning services (see the Genetic Testing section).<\/p>\n<\/div>\n<div><\/div>\n<div class=\"__UNKNOWN__\">\n<figure style=\"width: 392px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image26.png\" alt=\"A three-generation pedigree with three individuals with the trait shaded in. Please see text discussion for details.\" width=\"392\" height=\"215\" \/><figcaption class=\"wp-caption-text\">Figure 4.30: A pedigree depicting an example of recessive Mendelian inheritance like cystic fibrosis. Individuals may have a trait not observed in the previous generation. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-9\/\" target=\"_blank\">Mendelian recessive pattern of inheritance (Figure 3.35)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Beth Shook is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Pedigrees can also help distinguish if a health issue has either an <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_758\">autosomal<\/a> <\/strong>or <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_760\">X-linked<\/a><\/strong> pattern of inheritance. As previously discussed, there are 23 pairs of chromosomes and 22 of these pairs are known as autosomes. The provided pedigree examples (Figure 4.29-30) are autosomally linked genetic diseases. This means the genes that cause the disease are on one of the chromosomes numbered 1 to 22. The conditions caused by genes located on the X chromosome are referred to as X-linked diseases.<\/p>\n<p class=\"import-Normal\">Figure 4.31 depicts a family in which the mother is a carrier for the X-linked recessive disease Duchenne Muscular Dystrophy (DMD). The mother is a carrier for DMD, so daughters and sons will have a 50% chance of inheriting the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_762\">pathogenic<\/a><\/strong> <em>DMD<\/em> allele. Because females have two X chromosomes, females who inherit only one copy will not have the disease (although in rare cases, female carriers may show some symptoms of the disease). On the other hand, males who inherit a copy of an X-linked pathogenic <em>DMD<\/em> allele will typically be affected with the condition. Thus, males are more susceptible to X-linked conditions because they only have one X chromosome. Therefore, when evaluating a pedigree, if a higher proportion of males are affected with the disease, this could suggest the disease is X-linked recessive. <br style=\"clear: both\" \/><br style=\"clear: both\" \/>Compared to the X chromosome, the Y chromosome is smaller with only a few genes. Y-linked traits are therefore rare and can only be passed from a chromosomal father to a biological XY child.<\/p>\n<figure style=\"width: 407px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image27.jpg\" alt=\"A three-generation pedigree with four males and one female with the trait. Please see text discussion for details.\" width=\"407\" height=\"236\" \/><figcaption class=\"wp-caption-text\">Figure 4.31: A pedigree depicting an example of X-linked Mendelian inheritance like Duchenne Muscular Dystrophy (DMD). Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-9\/\" target=\"_blank\">X-linked recessive pattern of inheritance (Figure 3.36)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Beth Shook is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<h2 class=\"import-Normal\">Other Patterns of Inheritance<\/h2>\n<h3 class=\"import-Normal\"><strong>Complexity Surrounding Mendelian Inheritance<\/strong><\/h3>\n<p class=\"import-Normal\">Pea plant trait genetics are relatively simple compared to what we know about genetic inheritance today. The vast majority of genetically controlled traits are not strictly dominant or recessive, so the relationship among alleles and predicting phenotype is often more complicated. For example, traits that exhibit<strong> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_764\">incomplete dominance<\/a><\/strong> occur when a heterozygote exhibits a phenotype that is an intermediate phenotype of both alleles. In snapdragon flowers, the red flower color (R) is dominant and white is recessive (r). Therefore, the homozygous dominant RR is red and homozygous recessive rr is white. However, because the R allele is not completely dominant, the heterozygote Rr is a blend of red and white, which results in a pink flower (Figure 4.32).<\/p>\n<figure style=\"width: 302px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image28.png\" alt=\"Snapdragon flowers in many hues.\" width=\"302\" height=\"188\" \/><figcaption class=\"wp-caption-text\">Figure 4.32: Snap dragons with different genotypes resulting in different flower color phenotypes. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Antirrhinum_aka_Snap_dragon_at_lalbagh_7112.JPG\" target=\"_blank\">Antirrhinum a.k.a. Snap dragon at lalbagh 7112<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Rameshng\" target=\"_blank\">Rameshng<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">An example of incomplete dominance in humans is the enzyme \u03b2-hexosaminidase A (Hex A), which is encoded by the gene <em>HEXA<\/em>. Patients with two dysfunctional <em>HEXA <\/em>alleles are unable to metabolize a specific lipid-sugar molecule (GM2 ganglioside); because of this, the molecule builds up and causes damage to nerve cells in the brain and spinal cord. This condition is known as Tay-Sachs disease, and it usually appears in infants who are three to six months old. Most children with Tay-Sachs do not live past early childhood. Individuals who are heterozygous for the functional type <em>HEXA<\/em> allele and one dysfunctional allele have reduced Hex A activity. However, the amount of enzyme activity is still sufficient, so carriers do not exhibit any neurological phenotypes and appear healthy.<\/p>\n<p class=\"import-Normal\">Some genes and alleles can also have higher <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_766\">penetrance<\/a><\/strong> than others. Penetrance can be defined as the proportion of individuals who have a certain allele and also express an expected phenotype. If a genotype always produces an expected phenotype, then those alleles are said to be fully penetrant. However, in the case of incomplete (or reduced) penetrance, an expected phenotype may not occur even if an individual possesses the alleles that are known to control a trait or cause a disease.<\/p>\n<p class=\"import-Normal\">A well-studied example of genetic penetrance is the cancer-related genes <em>BRCA1<\/em> and <em>BRCA2<\/em>. Mutations in these genes can affect crucial processes such as DNA repair, which can lead to breast and ovarian cancers. Although <em>BRCA1<\/em> and <em>BRCA2<\/em> mutations have an autosomal dominant pattern of inheritance, it does not mean an individual will develop cancer if they inherit a pathogenic allele. Several lifestyle and environmental factors can also influence the risk for developing cancer. Regardless, if a family has a history of certain types of cancers, then it is often recommended that genetic testing be performed for individuals who are at risk. Moreover, publically available genetic testing companies are now offering health reports that include <em>BRCA1<\/em> and <em>BRCA2<\/em> allele testing (see the Genetic Testing section).<\/p>\n<h3 class=\"import-Normal\"><strong>Polygenic Traits<\/strong><\/h3>\n<p class=\"import-Normal\">While Mendelian traits tend to be influenced by a single gene, the vast majority of human phenotypes are <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_768\">polygenic traits<\/a><\/strong>. The term <em>polygenic<\/em> means \u201cmany genes.\u201d Therefore, a polygenic trait is influenced by many genes that work together to produce the phenotype. Human phenotypes such as hair color, eye color, height, and weight are examples of polygenic traits. Hair color, for example, is largely determined by the type and quantity of a pigment called melanin, which is produced by a specialized cell type within the skin called melanocytes. The quantity and ratio of melanin pigments determine black, brown, blond, and red hair colors. <em>MC1R<\/em> is a well-studied gene that encodes a protein expressed on the surface of melanocytes that is involved in the production of eumelanin pigment. Typically, people with two functional copies of <em>MC1R <\/em>have brown hair. People with reduced functioning <em>MC1R<\/em> allele copies tend to produce pheomelanin, which results in blond or red hair. However, <em>MC1R <\/em>alleles have variable penetrance, and studies are continually identifying new genes (e.g., <em>TYR<\/em>, <em>TYRP1<\/em>, <em>SLC24A5<\/em>, and <em>KITLG<\/em>) that also influence hair color. Individuals with two nonfunctioning copies of the gene <em>TYR<\/em> have a condition called oculocutaneous albinism\u2014their melanocytes are unable to produce melanin so these individuals have white hair, light eyes, and pale skin.<\/p>\n<p class=\"import-Normal\">In comparison to Mendelian diseases, <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_770\">complex diseases<\/a><\/strong> (e.g., Type II diabetes, coronary heart disease, Alzheimer's, and schizophrenia) are more prevalent in humans. Complex diseases are polygenic, but their development is also influenced by physical, environmental, sociocultural, and individual lifestyle factors. Families can be more predisposed to certain diseases; however, complex diseases often do not have a clear pattern of inheritance.<\/p>\n<p class=\"import-Normal\">Although research of complex traits and diseases continue, geneticists may not know all of the genes involved with a given complex disease. Additionally, how much genetic versus nongenetic determinants contribute to a disease phenotype can be difficult to decipher. Therefore, predicting individual medical risk and risk across different human populations is often a significant challenge. For instance, cardiovascular diseases (CVDs) continue to be one of the leading causes of death around the world. Development of CVDs has been linked to nutrient exposure during fetal development, high fat and sedentary lifestyles, drug usage, adverse socioeconomic conditions, and various genes. Human environments are diverse, and public health research including the field of Human Biology can help identify risk factors and behaviors associated with chronic diseases. Large-scale clinical genetic studies with powerful bioinformatic approaches can also help elucidate some of these complex relationships.<\/p>\n<h2 class=\"import-Normal\">Genomics and Epigenetics<\/h2>\n<p class=\"import-Normal\">A <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_772\">genome<\/a><\/strong> is all of the genetic material of an organism. In the case of humans, this includes 46 chromosomes and mtDNA. The human genome contains approximately three billion base pairs of DNA and has regions that are both noncoding and coding. Scientists now estimate that the human genome contains 20,000\u201325,000 protein-coding genes, with each chromosome containing a few hundred to a few thousand genes. As our knowledge of heredity increases, researchers have begun to realize the importance of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_774\">epigenetics<\/a><\/strong>, or changes in gene expression that do not result in a change of the underlying DNA sequence. Epigenetics research is also crucial for unraveling gene regulation, which involves complex interactions between DNA, RNA, proteins, and the environment.<\/p>\n<h3 class=\"import-Normal\"><strong>Genomics<\/strong><\/h3>\n<p class=\"import-Normal\">The vast majority of the human genome is noncoding, meaning there are no instructions to make a protein or RNA product in these regions. Historically, noncoding DNA was referred to as \u201cjunk DNA\u201d because these vast segments of the genome were thought to be irrelevant and nonfunctional. However, continual improvement of DNA <strong>sequencing<\/strong> technology along with worldwide scientific collaborations and consortia have contributed to our increased understanding of how the genome functions. Through these technological advances and collaborations, we have since discovered that many of these noncoding DNA regions are involved in dynamic genetic regulatory processes.<\/p>\n<p class=\"import-Normal\">Genomics is a diverse field of molecular biology that focuses on genomic evolution, structure, and function; gene mapping; and <strong>genotyping <\/strong>(determining the alleles present). Evolutionary genomics determined that humans share about 98.8% percent of their DNA with chimpanzees. Given the phenotypic differences between humans and chimpanzees, having a DNA sequence difference of 1.2% seems surprising. However, a lot of genomics research is also focused on understanding how noncoding genomic regions influence how individual genes are turned \u201con\u201d and \u201coff\u201d (i.e., regulated). Therefore, although DNA sequences are identical, regulatory differences in noncoding genetic regions (e.g., promoters) are believed to be largely responsible for the physical differences between humans and chimpanzees.<\/p>\n<p class=\"import-Normal\">Further understanding of genomic regulatory elements can lead to new therapies and personalized treatments for a broad range of diseases. For example, targeting the regulatory region of a pathogenic gene to \u201cturn off\u201d its expression can prevent its otherwise harmful effects. Such molecular targeting approaches can be personalized based on an individual\u2019s genetic makeup. Genome-wide association studies (GWAS), which seek to determine genes that are linked to complex traits and diseases, typically require significant computational efforts. This is because millions of DNA sequences must be analysed and GWAS sometimes include thousands of participants. During the beginning of the genomics field, most of the large-scale genomics studies only included North American, European, and East Asian participants and patients. Researchers are now focusing on increasing ethnic diversity in genomic studies and databases. In turn, accuracy of individual disease risk across all human populations will be improved and more rare disease\u2013causing alleles will be identified.<\/p>\n<h3 class=\"import-Normal\"><strong>Epigenetics<\/strong><\/h3>\n<p class=\"import-Normal\">All cells within your body have the same copy of DNA. For example, a brain neuron has the same DNA blueprint as does a skin cell on your arm. Although these cells have the same genetic information, they are considered specialized. The reason all cells within the body have the same DNA but different morphologies and functions is that different subsets of genes are turned \u201con\u201d and \u201coff\u201d within the different cell types. A more precise explanation is that there is differential expression of genes among different cell types. In the case of neuronal cells, a unique subset of genes are active that allow them to grow axons to send and receive messages. This subset of genes will be inactive in non-neuronal cell types such as skin cells. Epigenetics is a branch of genetics that studies how these genes are regulated through mechanisms that do not change the underlying DNA sequence.<\/p>\n<p class=\"import-Normal\">The prefix <em>epi-<\/em> means \u201con, above, or near,\u201d and epigenetic mechanisms such as <strong>DNA methylation<\/strong> and histone modifications occur on, above, or near DNA. The addition of a methyl group (\u2014 CH\u2083) to DNA is known as DNA methylation (Figure 4.33). DNA methylation and other modifications made to the histones around which DNA are wrapped are thought to make chromatin more compact. This DNA is inaccessible to transcription factors and RNA polymerases, thus preventing genes from being turned on (i.e., transcribed). Other histone modifications have the opposite effect by loosening chromatin, which makes genes accessible to transcription factors.<\/p>\n<figure style=\"width: 510px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image29.png\" alt=\"Epigenetic histone tail modifications that can tighten and loosen the chromatin of DNA. \" width=\"510\" height=\"395\" \/><figcaption class=\"wp-caption-text\">Figure 4.33: Different types of epigenetic histone tail modifications that can tighten (top) and loosen (bottom) the chromatin of DNA. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available.<\/a> Credit: <a href=\"https:\/\/cnx.org\/contents\/jVCgr5SL@15.43:5cz8bfb2@10\/16-3-Eukaryotic-Epigenetic-Gene-Regulation\" target=\"_blank\">Epigenetic Control (Biology 2e, Figure 16.7)<\/a> by<a href=\"https:\/\/openstax.org\/\" target=\"_blank\"> OpenStax<\/a> is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\" target=\"_blank\"> CC BY 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">It is important to note that environmental factors can alter DNA methylation and histone modifications and also that these changes can be passed from generation to generation. For example, someone\u2019s <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_782\">epigenetic profile<\/a><\/strong> can be altered during a stressful time (e.g., natural disasters, famine, etc.), and those regulatory changes can be inherited by the next generation. Moreover, our epigenetic expression profile changes as we age. For example, certain places in our genome become \u201chyper\u201d or \u201chypo\u201d methylated over time. Identical twins also have epigenetic profiles that become more different as they age. Researchers are only beginning to understand the significance of these genome-wide epigenetic changes. Scientists have also discovered that changes in epigenetic modifications can alter gene expression in ways that contribute to diseases. It is also important to note that, unlike DNA mutations (which permanently change the nucleotide sequence), epigenetic changes can be easily reversed. A lot of research now focuses on how drugs can alter or modulate changes in DNA methylation and histone modifications to treat diseases such as cancer.<\/p>\n<div class=\"textbox shaded no-borders\" style=\"background: var(--lightblue)\">\n<h2>Environmental Disruptors and Their Impact on Human Reproductive Systems<\/h2>\n<p>The National Institute of Environmental Health Sciences (NIEHS) defines endocrine-disrupting chemicals (EDCs) as synthetic or natural compounds that interfere with the body\u2019s hormonal systems. Found in pesticides, plastics, industrial chemicals, and pollutants, EDCs can mimic, block, or alter the natural action of hormones (NIEHS, 2024). Their effects on reproductive health are profound, particularly during critical developmental windows while also affecting subsequent generations through epigenetic changes.<\/p>\n<p>NIEHS declared EDC\u2019s:<\/p>\n<div align=\"center\">\n<table>\n<tbody>\n<tr>\n<td>Atrazine<\/td>\n<td>one of the most commonly applied herbicides in the world, often used to control weeds in corn, sorghum, and sugarcane crops.<\/td>\n<\/tr>\n<tr>\n<td>Bisphenol A (BPA)<\/td>\n<td>used to make polycarbonate plastics and epoxy resins. It is used in manufacturing, food packaging, toys, and other applications. BPA resins may be found in the lining of some canned foods and beverages.<\/td>\n<\/tr>\n<tr>\n<td>Dioxins<\/td>\n<td>a byproduct of certain manufacturing processes, such as herbicide production and paper bleaching. They can be released into the air from waste burning and wildfires.<\/td>\n<\/tr>\n<tr>\n<td>Perchlorate<\/td>\n<td>a colorless salt manufactured and used as an industrial chemical to make rockets, explosives, and fireworks, which can be found in some groundwater.<\/td>\n<\/tr>\n<tr>\n<td>Polyfluoroalkyl Substances (PFAS)<\/td>\n<td>a large group of chemicals used widely in industrial applications, such as firefighting foam, nonstick pans, paper, and textile coatings.<\/td>\n<\/tr>\n<tr>\n<td>Phthalates<\/td>\n<td>a large group of compounds used as liquid plasticizers. They are found in hundreds of products including some food packaging, cosmetics, fragrances, children\u2019s toys, and medical device tubing. Cosmetics that may contain phthalates include nail polish, hair spray, aftershave lotion, cleanser, and shampoo.<\/td>\n<\/tr>\n<tr>\n<td>Phytoestorgens<\/td>\n<td>naturally occurring substances with hormone-like activity found in some plants; they may have a similar effect to estrogen produced by the body. Soy foods, for example, contain phytoestrogens.<\/td>\n<\/tr>\n<tr>\n<td>Polybrominated diphenyl ethers (PBDE)<\/td>\n<td>used to make flame retardants for products such as furniture foam and carpet.<\/td>\n<\/tr>\n<tr>\n<td>Polychlorinated biphenyls (PCBs)<\/td>\n<td>used to make electrical equipment, such as transformers, and are in hydraulic fluids, heat transfer fluids, lubricants, and plasticizers. PCBs were mass-produced globally until they were banned in 1979.<\/td>\n<\/tr>\n<tr>\n<td>Triclosan<\/td>\n<td>an ingredient that was previously added to some antimicrobial and personal care products, like liquid body wash and soaps.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h3 style=\"text-align: left\">The Male Reproductive System: Vulnerabilities, Epigenetics, and Disruptions<\/h3>\n<p style=\"text-align: left\">The male reproductive system is highly sensitive to hormonal interference, especially during prenatal and early postnatal development. Over the past 50 years, epidemiological data gathered by the NIEHS has revealed alarming changes: increased cases of prostate and testicular cancers, male-descended testes, and anatomical malformations of male genitalia (Sweeney Et al., 2015). These changes are accompanied by a global decline in sperm quality, underscoring the widespread vulnerability of male reproductive health to environmental factors. The testes, as the site of sperm production and testosterone synthesis, are particularly susceptible to EDC interference. Proper testicular development depends on tightly regulated hormonal signalling, which EDCs can disrupt by mimicking or blocking hormones like testosterone and estrogen, leading to improper testicular formation and increased risk of testicular cancer. Prostate development is also a target for EDC interference. African American men, for example, exhibit twice the risk of developing prostate cancer than Caucasian men. This disparity has been attributed to hereditary, lifestyle, and environmental factors, often causing elevated maternal estrogen levels during gestation. This prenatal exposure to EDCs can mimic estrogen and predispose developing prostate tissues to cancerous changes in adulthood (2015).<\/p>\n<h3 style=\"text-align: left\">The Female Reproductive System: Epigenetics and Fertility Challenges<\/h3>\n<p style=\"text-align: left\">Female fertility relies on a delicate hormonal balance to regulate processes such as ovulation, implantation, and pregnancy. EDCs can disrupt this balance by mimicking, antagonizing, or altering the action of hormones. Their interference contributes to a wide range of reproductive disorders, including early puberty, premature ovarian failure, anovulation, and infertility. Epigenetics plays a central role in female reproductive health. DNA methylation, histone modifications, and ncRNA generation are crucial for regulating ovarian and uterine function; However, EDCs can affect these regulatory mechanisms. An example of this is primordial germ cells (PGCs) in female embryos, which need to undergo extensive epigenetic reprogramming during development (Biswas Et al., 2021). This process erases genomic imprinting and reactivates the inactive X chromosome, creating a \"blank slate\" for the next generation; however, EDCs can disrupt this critical period of epigenetic resetting, leading to long-term consequences for reproductive health.<\/p>\n<p style=\"text-align: left\">The ovarian follicle\u2013the functional unit of female reproduction\u2013is particularly vulnerable to these chemicals. Being exposed to EDCs can deplete the pool of these follicles, leading to temporary or permanent infertility (2021). Additionally, EDCs interfere with estrogen receptor function, a crucial regulator of female reproductive processes. These chemicals bind to these receptors, altering the recruitment of enzymes involved in histone modification and chromatin remodelling; this disrupts gene expression patterns critical for ovarian and uterine health. One striking example is diethylstilbestrol (DES), a synthetic estrogen once prescribed to pregnant women (2021). DES exposure has been linked to ovarian cancer in subsequent generations, highlighting the transgenerational effects of EDCs on the female reproductive system. In severe cases, EDCs induce multigenerational reproductive disorders, as observed in studies linking DES to ovarian cancer in the grandchildren of exposed individuals.<\/p>\n<\/div>\n<\/div>\n<h2 style=\"text-align: left\">Epigenetic Therapy<\/h2>\n<h3 style=\"text-align: left\">Heritable Changes and Some Related Drugs<\/h3>\n<p style=\"text-align: left\">As has been said, epigenetics involves heritable changes in gene expression, without involving DNA alteration. These changes, being heritable and often involving abnormal DNA methylation patterns within the four DNA methyltransferases (DNMTs) or histone modifications in chromatin, can lead to disease development. DNMTs (DNMT1, DNMT2, DNMT3A, and DNMT3B) have functions specific to themselves and are at the core of the DNA methylation process. Regarding the histone modifications mentioned, histones have been recognized to mutate under various mechanisms, such as acetylation, methylation and phosphorylation. The acetylation of histones involves histone acetyltransferases (HATs), which are associated with the activation of gene transcription. This process is reversed by the deacetylation of histones, which is associated with the silencing of gene transcription under histone deacetylases (HDACs). (Peedicayil, 2006)<\/p>\n<p style=\"text-align: left\">Epigenetic therapy, with the use of specialized drug developments, aims to correct epigenetic defects, which are reversible under pharmacological intervention, by targeting enzymes such as HATs, HDACs and DNMTs, as well as histone methyltransferases. For instance, certain drugs are being developed as DNMT inhibitors, stopping the methylation of DNA associated with inappropriate transcriptional silencing of genes, and potentially increasing haemoglobin F to help patients affected by sickle cell anemia. These DNMT inhibitor drugs have been classified under three categories based on their structures: nucleoside analogue DNMT inhibitors, non-nucleoside analogue DNMT inhibitors, and antisense oligonucleotides (2006). Nucleoside analogue DNMT inhibitors are analogues of cytosine, the nucleotide affected by methylation from DNMTs, and are incorporated into replicating DNA, replacing cytosine, thus being S-phase-specific drugs. Non-nucleoside analogue DNMT inhibitors are researched to reduce the myelotoxic effects of drugs directly incorporated into the DNA, and are brought into the patient differently. Antisense oligonucleotides are drugs made up of sequences of nucleotides complementary to mRNAs, made to block translation, by acting on the DNMT1 for instance. Additionally, drugs such as HDAC inhibitors help maintain the acetylation of histones, leading to apoptosis, growth arrest or differentiation of tumour cells, giving this drug an anticancer effect, suppressing tumour growth. (2006)<\/p>\n<h3 style=\"text-align: left\">Implications with Cancers<\/h3>\n<p style=\"text-align: left\">Research published in\u00a0<em>The Indian Journal for Medical Research<\/em> has shown that these drugs show promising results in cancer treatment trials involving solid tumours and hematological malignancies. However, they have limitations, for instance, the fact that DNMT and HDAC inhibitors could activate oncogenes due to limited specificity, leading to further tumor progression; or their high myelotoxicity levels, a side effect thought to be due to their incorporation into DNA, and nucleotide analogue inhibitors (2006). Though that is the case, it is important to know that epigenetic drugs alone or in combination with conventional anticancer drugs, may prove to be a significant advance over the use of conventional anticancer drugs, and may also be a way to prevent diseases. Additionally, combination therapy strategies targeting various epigenetic markers, such as DNMTs for cancer-related genes and non-selective HDAC inhibitors, have been shown to yield promising results, simultaneously inducing the expression of tumor suppressor genes and inhibiting the expression of key oncogenes.\u00a0<span style=\"margin: 0px;padding: 0px\">As recently explored by researchers in\u00a0<em>Cell Death Discovery<\/em>, this specific case of combination therapy would synergistically induce gene expression while maintaining the selectivity required to increase targeting of particular tumor types based on gene expression profiles.<\/span> (Yu Et al., 2024)<\/p>\n<p style=\"text-align: left\">To date, the majority of cases in which epigenetic defects have led to disease pathogenesis are cancers (Peedicayil, 2006), cancer cells often developing due to uncontrolled cell growth and resistance to cell death mechanisms, made possible with abnormal DNA methylation patterns as well as histone modifications (Yu Et al., 2024). Epigenetic alterations have therefore been identified within the core of tumor progression mechanisms in cancer cells, including tumorigenesis, promotion, progression, and recurrence, suggesting epigenetic heterogeneity at the cellular level (2024). Certain drugs have been developed, showing specifically good results for cancer treatments, by inhibiting enzymes such as KMTs and KDMs. These can be added to the growing list of drugs fitting into epigenetic therapy, including DNMT and HDAC inhibitors, as well as combination therapy treatments, for cancer and other diseases.<\/p>\n<h3 style=\"text-align: left\">Purpose of Study and Future Developments<\/h3>\n<p style=\"text-align: left\">Studying the link between epigenetics and diseases is crucial for multiple reasons, one of which is enabling scientists and researchers to better understand disease mechanisms, detect abnormal epigenetic changes, and, in turn, develop more effective treatments or possibly even prevent diseases from developing in the first place. As previously mentioned, epigenetic therapy has been shown to bring promising results in drug trials surrounding cancer treatments. Still, the range of diseases to be treated with this new pharmacology approach is vast, molecules other than DNMTs and HDACs being related to epigenetic mechanisms within gene expression, such as BET proteins and KDMs, potentially being a source of new medications or treatments (Yu Et al., 2024; Peedicayil, 2006). Additionally, by understanding someone's epigenetic profile, a form of personalized \u201cprecision medicine\u201d (2024, p. 8) is developed, offering less toxic and more effective treatments with fewer undesired side effects. Researchers expanding this field of knowledge would be able to understand, in more concrete terms, how external factors are linked to epigenetic changes and, consequently, disease risk, potentially halting disease progression and developing new prevention mechanisms. Personalized medicine combines both genetic and epigenetic data, including gene expression profiles, DNA methylation patterns, histone modification profiles, and identified biomarkers, to create precise disease management and prediction.<\/p>\n<p style=\"text-align: left\">It is crucial to keep in mind that diseases like cancer are linked to major causes of morbidity and mortality worldwide, which could be reduced with therapeutic medicine such as epigenetic therapy, aiming to detect cancer biomarkers to improve risk assessment, diagnosis, and targeted treatment interventions, limiting the burden of chronic and life-threatening diseases. With the advancement of epigenetic therapies, new sequencing techniques, as well as AI (2024), have opened avenues to establish precision diagnostics and therapeutics for patients.<\/p>\n<p style=\"text-align: left\">With this said, epigenetics is a relatively new area of scientific research. This field has exploded in the last few decades, especially with the advancement of technologies that allow researchers to examine DNA methylation patterns, histone modifications, and non-coding RNA molecules across the genome. While the potential of epigenetics in explaining complex diseases, including those linked to environmental factors such as endocrine-disrupting chemicals (EDCs), is immense, we\u2019ve identified two key challenges. One major limitation is the complexity and variability of epigenetic marks. These modifications can differ significantly across cell types, tissues, and even individuals, making it difficult to generalize findings.<\/p>\n<p style=\"text-align: left\">Additionally, epigenetic changes are dynamic and can fluctuate over time, which complicates the task of linking them to specific environmental exposures or health outcomes. Another challenge lies in the transgenerational aspect of epigenetics. While it's clear that epigenetic changes can be passed from one generation to the next, the mechanisms behind this inheritance are not fully understood. It's also difficult to pinpoint exactly when and how these modifications occur in development, especially since environmental exposures may affect individuals at different stages of their life, with varying effects depending on the timing and dose.<\/p>\n<div class=\"textbox\">\n<h2>Special Topic: Epigenetics and X Chromosome Inactivation<\/h2>\n<figure style=\"width: 181px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image30.jpg\" alt=\"A cat that has a multicolored coat pattern in colors of black, orange, and white.\" width=\"181\" height=\"201\" \/><figcaption class=\"wp-caption-text\">Figure 4.34: A multicolored coat pattern as the result of X chromosome inactivation during development. Credit: \u201cRue\u201d the calico cat by Hayley Mann is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\"> CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p>Mary Lyon was a British geneticist who presented a hypothesis for X chromosome inactivation (called the <em>Lyon hypothesis<\/em>) based on her work and other studies of the day. Females inherit two X chromosomes, one from each parent. Males have one functional X chromosome; however, this does not mean females have more active genes than males. During the genetic embryonic development of many female mammals, one of the X chromosomes is inactivated at random, so females have one functional X chromosome. The process of X chromosome inactivation in females occurs through epigenetic mechanisms, such as DNA methylation and histone modifications. Recent studies have analysed the role of a long noncoding RNA called X-inactive specific transcript (XIST), which is largely responsible for the random silencing of one of the X chromosomes. The presence of two X chromosomes is the signal for XIST RNA to be expressed so that one X chromosome can be inactivated. However, some cells may have an active paternal X chromosome while other cells may have an active maternal X chromosome. This phenomenon is easily seen in calico and tortoiseshell cats (Figure 4.34). In cats, the gene that controls coat color is found on the X chromosome. During early embryo development, random inactivation of X chromosomes gives rise to populations of cells that express black or orange, which results in the unique coat patterning. Therefore, calico cats are typically always female.<\/p>\n<\/div>\n<h2 class=\"import-Normal\">Genetic Testing<\/h2>\n<p class=\"import-Normal\">To assist with public health efforts, newborn screening for genetic diseases has been available in the United States for over 50 years. One of the first available genetic tests was to confirm a phenylketonuria (PKU) diagnosis in infants, which is easily treatable with a dietary change. Currently, each state decides what genes are included on newborn screening panels and some states even have programs to help with infant medical follow-ups. There are now hundreds of laboratories that provide testing for a few thousand different genes that can inform medical decisions for infants and adults. Moreover, genetic testing has been made available publicly to anyone without the assistance of medical professionals.<\/p>\n<h3 class=\"import-Normal\"><strong>Clinical Testing<\/strong><\/h3>\n<p class=\"import-Normal\">Clinical genetics tests assist patients with making medically informed decisions about family planning and health. Applications of this technology include assistance with<em> in vitro<\/em> fertilization (IVF) procedures, embryo genetic screening, and personalized medicine such as matching patients to cancer therapies. To ensure accuracy of patient genetic screening, it is important that all clinical laboratories are regulated. The Clinical Laboratory Improvement Amendments (CLIA) are United States federal standards that all human laboratory testing clinics must follow. A major benefit provided by some clinical genetic testing companies is access to genetic counselors, who have specialized education and training in medical genetics and counseling. For individuals with a family history of genetic disease, a physician may recommend genetic carrier screening to see if there is a risk for passing on a disease to a child. Genetic counselors provide expertise with interpretation of genetic testing results, as well as help guide and support patients when making impactful medical decisions.<\/p>\n<h2>Cultural Connections and Contemporary Implications<\/h2>\n<p>From the late nineteenth century to the present, humanity\u2019s desire to direct its own biological destiny has raised profound questions for biological anthropologists. The study of human evolution is not only a scientific exploration of change over time\u2014it is also a reflection of how societies interpret difference, fitness, and social value. The history of eugenics, and its modern echoes in genomic technology, reveal how evolutionary theory can be misused to justify inequality, as well as how culture continues to shape the biological future of our species.<\/p>\n<p>The roots of eugenics lie in Social Darwinism, where figures such as Francis Galton (a cousin of Darwin) believed that basic natural selection was insufficient, opting for more involved methods of social engineering through selective breeding. This perspective assumed that complex human traits such as intelligence, morality, or poverty could be biologically inherited and thus controlled. In this view, biological determinism replaced social responsibility, and \u201cfitness\u201d became a political and cultural judgment rather than a biological one.<\/p>\n<p>Throughout the early twentieth century, eugenic policies spread across the globe, shaping laws and public health initiatives. In Canada, government-backed programs continuing into the 1970s, enforced the sterilization of Indigenous women, coercing them with threats of withdrawing future healthcare. Germany famously drew upon such precedents in developing its racial hygiene programs during the Second World War, transforming eugenic ideology into a state-sponsored campaign of genocide. Even by the late twentieth century, echoes of eugenics persisted in Peru, where population control initiatives targeted Indigenous communities for compulsory sterilization.<\/p>\n<p>In the modern genomic era, new technologies involving gene therapy and genetic testing present both promise and fear. The ability to modify or select genes reawakens many of the same moral dilemmas that eugenics once posed. From a biological anthropological perspective, the danger lies not in studying or applying genetics itself, but in assuming that genes alone determine destiny. The human ecosystem operates within systems where culture, environment, and biology continuously interact; attempts to reduce behaviour, intelligence, or worth to genetic codes ignore these relationships that define humanity.<\/p>\n<p>As Steven Pinker argues when commenting on his book <em>The Blank Slate<\/em>, there have been two ideologies that have led to genocide: eugenics and Marxism. Marxism disregarded the idea of biology and race as well as human nature. Thus, it is not solely inheritance (genes) that leads to genocide, but the overall belief that humanity can and should be remade through coercive means. Biological anthropology reminds us that human variation\u2014both cultural and genetic\u2014is the foundation of adaptability. To purposely limit diversity through selective reproduction or genetic homogenization is to weaken humans\u2019 capacity to evolve, both biologically and ethically.<\/p>\n<h4>Discussion questions<\/h4>\n<ul>\n<li>What are the limits in parental selection for an offspring\u2019s genetics?<\/li>\n<li>Consider the 1-child policy in China. What are some of the problems engendered by that policy?<\/li>\n<\/ul>\n<div class=\"textbox shaded\">\n<h2 class=\"import-Normal\">Review Questions<\/h2>\n<ul>\n<li class=\"import-Normal\">What is the purpose of DNA replication? Explain in a few sentences what happens during DNA replication. When do DNA mutations happen? And how does this create phenotypic variation (i.e., different phenotypes of the same physical trait)?<\/li>\n<li class=\"import-Normal\">Using your own words, what are homologous chromosomes and sister chromatids? What are the key differences between mitosis and meiosis?<\/li>\n<li class=\"import-Normal\">Determine if the pedigree diagram below (Figure 4.40) represents an autosomal dominant, autosomal recessive, or X-linked recessive pattern of inheritance. You should write the genotype (i.e., AA, Aa, or aa) above each square to help you (note: there may sometimes be two possible answers for a square\u2019s genotype). Please also explain why you concluded a particular pattern of inheritance.<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n<figure style=\"width: 247px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image36.png\" alt=\"Pedigree where 6 of 15 individuals have the trait. On 2 separate branches parents without the trait have a biological child who does.\" width=\"247\" height=\"214\" \/><figcaption class=\"wp-caption-text\">Figure 4.40: A four generation pedigree depicting a trait with an undetermined inheritance pattern. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-9\/\" target=\"_blank\">X-linked recessive pattern of inheritance (Figure 3.46)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Beth Shook is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<ul>\n<li class=\"import-Normal\">Use base pairing rules to transcribe the following DNA template sequence into mRNA: GTAAAGGTGCTGGCCATC. Next, use the protein codon table (see Figure 4.21) to translate the sequence. In regard to transcription, explain what the significance is of the first and last codon\/protein in the sequence.<\/li>\n<li class=\"import-Normal\">In your opinion, what do you think the benefits are of direct-to-consumer (DTC) genetic testing? What are the drawbacks and\/or greater ethical concerns? Do you think benefits outweigh concerns?<\/li>\n<li class=\"import-Normal\">Imagine that you submit your DNA sample to a genetic testing company and among the various diseases for which they test, there is an allele that is associated with late-onset Alzheimer\u2019s disease. You have the option to view your Alzheimer\u2019s result or to not view your result. What do you do and why?<\/li>\n<\/ul>\n<\/div>\n<h2 class=\"import-Normal\">Key Terms<\/h2>\n<p class=\"import-Normal\"><strong>Adenosine triphosphate (ATP)<\/strong>: A high-energy compound produced by mitochondria that powers cellular processes.<\/p>\n<p class=\"import-Normal\"><strong>Allele<\/strong>: A nonidentical DNA sequence found in the same gene location on a homologous chromosome, or gene copy, that codes for the same trait but produces a different phenotype.<\/p>\n<p class=\"import-Normal\"><strong>Amino acids<\/strong>: Organic molecules that are the building blocks of protein. Each of the 20 different amino acids have their own unique chemical property. Amino acids are chained together to form proteins.<\/p>\n<p class=\"import-Normal\"><strong>Ancient DNA (aDNA)<\/strong>: DNA that is extracted from organic remains and that often dates from hundreds to thousands of years ago. Also, aDNA is typically degraded (i.e., damaged) due to exposure to the elements such as heat, acidity, and humidity.<\/p>\n<p class=\"import-Normal\"><strong>Aneuploid<\/strong>: A cell with an unexpected amount of chromosomes. The loss or gain of chromosomes can occur during mitotic or meiotic division.<\/p>\n<p class=\"import-Normal\"><strong>Antibodies<\/strong>: Immune-related proteins that can detect and bind to foreign substances in the blood such as pathogens.<\/p>\n<p class=\"import-Normal\"><strong>Apoptosis<\/strong>: A series of molecular steps that is activated leading to cell death. Apoptosis can be activated when a cell fails checkpoints during the cell cycle; however, cancer cells have the ability to avoid apoptosis.<\/p>\n<p class=\"import-Normal\"><strong>Autosomal<\/strong>: Refers to a pattern of inheritance in which an allele is located on an autosome (non sex chromosome).<\/p>\n<p class=\"import-Normal\"><strong>Base pairs<\/strong>: Chemical bonding between nucleotides. In DNA, adenine (A) pairs with thymine (T) and cytosine (C) pairs with guanine (G); in RNA, adenine (A) always pairs with uracil (U).<\/p>\n<p class=\"import-Normal\"><strong>Carbohydrate<\/strong>: Molecules composed of carbon and hydrogen atoms that can be broken down to supply energy.<\/p>\n<p class=\"import-Normal\"><strong>Carrier<\/strong>: An individual who has a heterozygous genotype that is typically associated with a disease.<\/p>\n<p class=\"import-Normal\"><strong>Cell cycle<\/strong>: A cycle the cell undergoes with checkpoints between phases to ensure that DNA replication and cell division occur properly.<\/p>\n<p class=\"import-Normal\"><strong>Cell surface antigen<\/strong>: A protein that is found on a red blood cell\u2019s surface.<\/p>\n<p class=\"import-Normal\"><strong>Centromere<\/strong>: A structural feature that is defined as the \u201ccenter\u201d of a chromosome and that creates two different arm lengths. This term also refers to the region of attachment for microtubules during mitosis and meiosis.<\/p>\n<p class=\"import-Normal\"><strong>Chromatin<\/strong>: DNA wrapped around histone complexes. During cell division, chromatin becomes a condensed chromosome.<\/p>\n<p class=\"import-Normal\"><strong>Chromosome<\/strong>: DNA molecule that is wrapped around protein complexes, including histones.<\/p>\n<p class=\"import-Normal\"><strong>Codominance<\/strong>: The effects of both alleles in a genotype can be seen in the phenotype.<\/p>\n<p class=\"import-Normal\"><strong>Codons<\/strong>: A sequence that comprises three DNA nucleotides that together code for a protein.<\/p>\n<p class=\"import-Normal\"><strong>Complex diseases<\/strong>: A category of diseases that are polygenic and are also influenced by environment and lifestyle factors.<\/p>\n<p class=\"import-Normal\"><strong>Cytoplasm<\/strong>: The \u201cjelly-like\u201d matrix inside of the cell that contains many organelles and other cellular molecules.<\/p>\n<p class=\"import-Normal\"><strong>Deleterious<\/strong>: A mutation that increases an organism\u2019s susceptibility to disease.<\/p>\n<p class=\"import-Normal\"><strong>Deoxyribonucleic acid (DNA)<\/strong>: A molecule that carries the hereditary information passed down from parents to offspring. DNA can be described as a \u201cdouble helix\u201d\u2019 shape. It includes two chains of nucleotides held together by hydrogen bonds with a sugar phosphate backbone.<\/p>\n<p class=\"import-Normal\"><strong>Diploid<\/strong>: Refers to an organism or cell with two sets of chromosomes.<\/p>\n<p class=\"import-Normal\"><strong>DNA methylation<\/strong>: Methyl groups bind DNA, which modifies the transcriptional activity of a gene by turning it \u201con\u201d or \u201coff.\u201d<\/p>\n<p class=\"import-Normal\"><strong>DNA polymerase<\/strong>: Enzyme that adds nucleotides to existing nucleic acid strands during DNA replication. These enzymes can be distinguished by their processivity (e.g., DNA replication).<\/p>\n<p class=\"import-Normal\"><strong>DNA replication<\/strong>: Cellular process in which DNA is copied and doubled.<\/p>\n<p class=\"import-Normal\"><strong>DNA sequence<\/strong>: The order of nucleotide bases. A DNA sequence can be short, long, or representative of entire chromosomes or organismal genomes.<\/p>\n<p class=\"import-Normal\"><strong>Dominant<\/strong>: Refers to an allele for which one copy is sufficient to be visible in the phenotype.<\/p>\n<p class=\"import-Normal\"><strong>Elongation<\/strong>: The assembly of new DNA from template strands with the help of DNA polymerases.<\/p>\n<p class=\"import-Normal\"><strong>Enzymes<\/strong>: Proteins responsible for catalyzing (accelerating) various biochemical reactions in cells.<\/p>\n<p class=\"import-Normal\"><strong>Epigenetic profile<\/strong>: The methylation pattern throughout a genome\u2014that is, which genes (and other genomic sites) are methylated and unmethylated.<\/p>\n<p class=\"import-Normal\"><strong>Epigenetics<\/strong>: Changes in gene expression that do not result in a change of the underlying DNA sequence. These changes typically involve DNA methylation and histone modifications. These changes are reversible and can also be inherited by the next generation.<\/p>\n<p class=\"import-Normal\"><strong>Euchromatin<\/strong>: Loosely coiled chromosomes found within the nucleus that are accessible for regulatory processing of DNA.<\/p>\n<p class=\"import-Normal\"><strong>Eukaryote<\/strong>: Single-celled or multicelled organism characterized by a distinct nucleus, with each organelle surrounded by its own membrane.<\/p>\n<p class=\"import-Normal\"><strong>Exon<\/strong>: Protein-coding segment of a gene.<\/p>\n<p class=\"import-Normal\"><strong>Gametes<\/strong>: Haploid cells referred to as an egg and sperm that will fuse together during sexual reproduction to form a diploid organism.<\/p>\n<p class=\"import-Normal\"><strong>Gene<\/strong>: Segment of DNA that contains protein-coding information and various regulatory (e.g., promoter) and noncoding (e.g., introns) regions.<\/p>\n<p class=\"import-Normal\"><strong>Genetic recombination<\/strong>: A cellular process that occurs during meiosis I in which homologous chromosomes pair up and sister chromatids on different chromosomes physically swap genetic information.<\/p>\n<p class=\"import-Normal\"><strong>Genome<\/strong>: All the genetic information of an organism.<\/p>\n<p class=\"import-Normal\"><strong>Genotype<\/strong>: The combination of two alleles that code for or are associated with the same gene.<\/p>\n<p class=\"import-Normal\"><strong>Genotyping<\/strong>: A molecular procedure that is performed to test for the presence of certain alleles or to discover new ones.<\/p>\n<p class=\"import-Normal\"><strong>Germ cells<\/strong>: Specialized cells that form gametes (egg and sperm cells).<\/p>\n<p class=\"import-Normal\"><strong>Haploid<\/strong>: Cell or organism with one set of chromosomes (<em>n<\/em> = 23).<\/p>\n<p class=\"import-Normal\"><strong>Helicase<\/strong>: A protein that breaks the hydrogen bonds that hold double-stranded DNA together.<\/p>\n<p class=\"import-Normal\"><strong>Heterozygous<\/strong>: Genotype that consists of two different alleles.<\/p>\n<p class=\"import-Normal\"><strong>Histones<\/strong>: Proteins that DNA wraps around to assist with DNA organization within the nucleus.<\/p>\n<p class=\"import-Normal\"><strong>Homologous chromosomes<\/strong>: A matching pair of chromosomes wherein one chromosome is maternally inherited and the other is paternally inherited.<\/p>\n<p class=\"import-Normal\"><strong>Homozygous<\/strong>: Genotype that consists of two identical alleles.<\/p>\n<p class=\"import-Normal\"><strong>Incomplete dominance<\/strong>: Heterozygous genotype that produces a phenotype that is a blend of both alleles.<\/p>\n<p class=\"import-Normal\"><strong>Initiation<\/strong>: The recruitment of proteins to separate DNA strands and begin DNA replication.<\/p>\n<p class=\"import-Normal\"><strong>Interphase<\/strong>: Preparatory period of the cell cycle when increased metabolic demand allows for DNA replication and doubling of the cell prior to cell division.<\/p>\n<p class=\"import-Normal\"><strong>Introns<\/strong>: Segment of DNA that does not code for proteins.<\/p>\n<p class=\"import-Normal\"><strong>Karyotyping<\/strong>: The microscopic procedure wherein the number of chromosomes in a cell is determined.<\/p>\n<p class=\"import-Normal\"><strong>Lagging strand<\/strong>: DNA template strand that is opposite to the leading strand during DNA replication. This strand is created in several disconnected sections and other enzymes fill in the missing nucleotide gaps between these sections.<\/p>\n<p class=\"import-Normal\"><strong>Leading strand<\/strong>: DNA template strand in which replication proceeds continuously.<\/p>\n<p class=\"import-Normal\"><strong>Lipids<\/strong>: Fatty acid molecules that serve various purposes in the cell, including energy storage, cell signaling, and structure.<\/p>\n<p class=\"import-Normal\"><strong>Meiosis<\/strong>: The process that gametes undergo to divide. The end of meiosis results in four haploid daughter cells.<\/p>\n<p class=\"import-Normal\"><strong>Mendelian genetics<\/strong>: A classification given to phenotypic traits that are controlled by a single gene.<\/p>\n<p class=\"import-Normal\"><strong>Messenger RNA (mRNA)<\/strong>: RNA molecule that is transcribed from DNA. Its tri-nucleotide codons are \u201cread\u201d by a ribosome to build a protein.<\/p>\n<p class=\"import-Normal\"><strong>Microarray technology<\/strong>: A genotyping procedure that utilizes a microarray chip, which is a collection of thousands of short nucleotide sequences attached to a solid surface that can probe genomic DNA.<\/p>\n<p class=\"import-Normal\"><strong>Microbiome<\/strong>: The collective genomes of the community of microorganisms that humans have living inside of their bodies.<\/p>\n<p class=\"import-Normal\"><strong>Mitochondrial DNA (mtDNA)<\/strong>: Circular DNA segment found in mitochondria that is inherited maternally.<\/p>\n<p class=\"import-Normal\"><strong>Mitochondrion<\/strong>: Specialized cellular organelle that is the site for energy production. It also has its own genome (mtDNA).<\/p>\n<p class=\"import-Normal\"><strong>Mitosis<\/strong>: The process that somatic cells undergo to divide. The end of mitosis results in two diploid daughter cells.<\/p>\n<p class=\"import-Normal\"><strong>Molecular anthropologists<\/strong>: Individuals who use molecular techniques (primarily genetics) to compare ancient and modern populations and to study living populations of humans and nonhuman primates.<\/p>\n<p class=\"import-Normal\"><strong>Molecular geneticists<\/strong>: Biologists that study the structure and function of genes.<\/p>\n<p class=\"import-Normal\"><strong>Mutation<\/strong>: A nucleotide sequence variation from the template DNA strand that can occur during replication. Mutations can also happen during recombination.<\/p>\n<p class=\"import-Normal\"><strong>Next-generation sequencing<\/strong>: A genotyping technology that involves producing millions of nucleotide sequences (from a single DNA sample) that are then read with a sequencing machine. It can be used for analyzing entire genomes or specific regions and requires extensive program-based applications.<\/p>\n<p class=\"import-Normal\"><strong>Nuclear envelope<\/strong>: A double-layered membrane that encircles the nucleus.<\/p>\n<p class=\"import-Normal\"><strong>Nucleic acid<\/strong>: A complex structure (like DNA or RNA) that carries genetic information about a living organism.<\/p>\n<p class=\"import-Normal\"><strong>Nucleotide<\/strong>: The basic structural component of nucleic acids, which includes DNA (A, T, C, and G) and RNA (A, U, C, and G).<\/p>\n<p class=\"import-Normal\"><strong>Nucleus<\/strong>: Double-membrane cellular organelle that helps protect DNA and also regulates nuclear activities.<\/p>\n<p class=\"import-Normal\"><strong>Organelle<\/strong>: A structure within a cell that performs specialized tasks that are essential for the cell. There are different types of organelles, each with its own function.<\/p>\n<p class=\"import-Normal\"><strong>Pathogenic<\/strong>: A genetic mutation (i.e., allele) that has a harmful phenotypic disease-causing effect.<\/p>\n<p class=\"import-Normal\"><strong>Pedigree<\/strong>: A diagram of family relationships that indicates which members may have or carry certain genetic and\/or phenotypic traits.<\/p>\n<p class=\"import-Normal\"><strong>Penetrance<\/strong>: The proportion of how often the possession of an allele results in an expected phenotype. Some alleles are more penetrant than others.<\/p>\n<p class=\"import-Normal\"><strong>Phenotype<\/strong>: The physical appearance of a given trait.<\/p>\n<p class=\"import-Normal\"><strong>Phospholipid bilayer<\/strong>: Two layers of lipids that form a barrier due to the properties of a hydrophilic (water-loving) head and a hydrophobic (water-repelling) tail.<\/p>\n<p class=\"import-Normal\"><strong>Polygenic trait<\/strong>: A phenotype that is controlled by two or more genes.<\/p>\n<p class=\"import-Normal\"><strong>Polymerase chain reaction (PCR)<\/strong>: A molecular biology procedure that can make copies of genomic DNA segments. A small amount of DNA is used as a starting template and is then used to make millions of copies.<\/p>\n<p class=\"import-Normal\"><strong>Prokaryote<\/strong>: A single-celled organism characterized by the lack of a nucleus and membrane-enclosed organelles.<\/p>\n<p class=\"import-Normal\"><strong>Promoter<\/strong>: The region of a gene that initiates transcription. Transcription factors can bind and DNA methylation may occur at a promoter site, which can modify the transcriptional activities of a gene.<\/p>\n<p class=\"import-Normal\"><strong>Protein<\/strong>: Chain of amino acids that folds into a three-dimensional structure that allows a cell to function in a variety of ways.<\/p>\n<p class=\"import-Normal\"><strong>Protein synthesis<\/strong>: A multi-step process by which amino acids are strung together by RNA machinery read from a DNA template.<\/p>\n<p class=\"import-Normal\"><strong>Recessive<\/strong>: Refers to an allele whose effect is not normally seen unless two copies are present in an individual\u2019s genotype.<\/p>\n<p class=\"import-Normal\"><strong>Ribonucleic acid (RNA)<\/strong>: Single-stranded nucleic acid molecule.There are different RNAs found within cells and they perform a variety of functions, such as cell signaling and involvement in protein synthesis.<\/p>\n<p class=\"import-Normal\"><strong>Ribosomal RNA (rRNA)<\/strong>: A ribosome-bound molecule that is used to correctly assemble amino acids into proteins.<\/p>\n<p class=\"import-Normal\"><strong>Ribosome<\/strong>: An organelle in the cell found in the cytoplasm or endoplasmic reticulum. It is responsible for reading mRNA and protein assemblage.<\/p>\n<p class=\"import-Normal\"><strong>RNA polymerase<\/strong>: An enzyme that catalyzes the process of making RNA from a DNA template.<\/p>\n<p class=\"import-Normal\"><strong>Sanger-sequencing<\/strong>: A process that involves the usage of fluorescently labeled nucleotides to visualize DNA (PCR fragments) at the nucleotide level.<\/p>\n<p class=\"import-Normal\"><strong>Semi-conservative replication<\/strong>: DNA replication in which new DNA is replicated from an existing DNA template strand.<\/p>\n<p class=\"import-Normal\"><strong>Sequencing<\/strong>: A molecular laboratory procedure that produces the order of nucleotide bases (i.e., sequences).<\/p>\n<p class=\"import-Normal\"><strong>Sister chromatids<\/strong>: During DNA replication, sister chromatids are produced on the chromosome. In cell division, sister chromatids are pulled apart so that two cells can be formed. In meiosis, sister chromatids are also the sites of genetic recombination.<\/p>\n<p class=\"import-Normal\"><strong>Somatic cells<\/strong>: Diploid cells that comprise body tissues and undergo mitosis for maintenance and repair of tissues.<\/p>\n<p class=\"import-Normal\"><strong>Splicing<\/strong>: The process by which mature mRNAs are produced. Introns are removed (spliced) and exons are joined together.<\/p>\n<p class=\"import-Normal\"><strong>Sugar phosphate backbone<\/strong>: A biochemical structural component of DNA. The \u201cbackbone\u201d consists of deoxyribose sugars and phosphate molecules.<\/p>\n<p class=\"import-Normal\"><strong>Telomere<\/strong>: A compound structure located at the ends of chromosomes to help protect the chromosomes from degradation after every round of cell division.<\/p>\n<p class=\"import-Normal\"><strong>Termination<\/strong>: The halt of DNA replication activity that occurs when a DNA sequence \u201cstop\u201d codon is encountered.<\/p>\n<p class=\"import-Normal\"><strong>Tissue<\/strong>: A cluster of cells that are morphologically similar and perform the same task.<\/p>\n<p class=\"import-Normal\"><strong>Transcription<\/strong>: The process by which DNA nucleotides (within a gene) are copied, which results in a messenger RNA molecule.<\/p>\n<p class=\"import-Normal\"><strong>Transcription factors<\/strong>: Proteins that bind to regulatory regions of genes (e.g., promoter) and increase or decrease the amount of transcriptional activity of a gene, including turning them \u201con\u201d or \u201coff.\u201d<\/p>\n<p class=\"import-Normal\"><strong>Transfer RNA (tRNA)<\/strong>: RNA molecule involved in translation. Transfer RNA transports amino acids from the cell\u2019s cytoplasm to a ribosome.<\/p>\n<p class=\"import-Normal\"><strong>Translation<\/strong>: The process by which messenger RNA codons are read and amino acids are \u201cchained together\u201d to form proteins.<\/p>\n<p class=\"import-Normal\"><strong>X-linked<\/strong>: Refers to a pattern of inheritance where the allele is located on the X or Y chromosome.<\/p>\n<h2 class=\"import-Normal\">For Further Exploration<\/h2>\n<p class=\"import-Normal\"><a href=\"https:\/\/www.genome.gov\/\">National Human Genome Research Institute<\/a><\/p>\n<p class=\"import-Normal\"><a href=\"https:\/\/ghr.nlm.nih.gov\/\">Genetics Home Reference<\/a><\/p>\n<p class=\"import-Normal\"><a href=\"https:\/\/knowgenetics.org\/\">Genetics Generation<\/a><\/p>\n<p class=\"import-Normal\"><a href=\"https:\/\/www.yourgenome.org\/\">yourgenome<\/a><\/p>\n<p class=\"import-Normal\">NOVA. 2018. Gene Sequencing Speeds Diagnosis of Deadly Newborn Diseases. NOVA, March 7, 2018. Accessed January 31, 2023. <a class=\"rId164\" href=\"https:\/\/www.pbs.org\/wgbh\/nova\/next\/body\/newborn-gene-sequencing\/\">https:\/\/www.pbs.org\/wgbh\/nova\/next\/body\/newborn-gene-sequencing\/<\/a>.<\/p>\n<p class=\"import-Normal\">Zimmer, Carl. N.d. \u201cCarl Zimmer\u2019s Game of Genomes.\u201d STATnews. Accessed January 31, 2023. <a class=\"rId165\" href=\"https:\/\/www.statnews.com\/feature\/game-of-genomes\/season-one\/\">https:\/\/www.statnews.com\/feature\/game-of-genomes\/season-one\/<\/a>.<\/p>\n<p class=\"import-Normal\">Illumina. 2016. \u201cIllumina Sequencing by Synthesis.\u201d YouTube.com, October 5, 2016. Accessed January 31, 2023. <a class=\"rId166\" href=\"https:\/\/www.youtube.com\/watch?v=fCd6B5HRaZ8\">https:\/\/www.youtube.com\/watch?v=fCd6B5HRaZ8<\/a>.<\/p>\n<h2 class=\"import-Normal\">References<\/h2>\n<p class=\"import-Normal\">Aartsma-Rus, Annemieke, Ieke B. Ginjaar, and Kate Bushby. 2016. \u201cThe Importance of Genetic Diagnosis for Duchenne Muscular Dystrophy.\u201d Journal of Medical Genetics 53 (3): 145\u2013151.<\/p>\n<p class=\"import-Normal\">Acuna-Hidalgo, Rocio, Joris A. Veltman, and Alexander Hoischen. 2016. \u201cNew Insights into the Generation and Role of De Novo Mutations in Health and Disease.\u201d Genome Biology 17 (241): 1\u201319.<\/p>\n<p class=\"import-Normal\">Albert, Benjamin, Susanna Tomassetti, Yvonne Gloor, Daniel Dilg, Stefano Mattarocci, Slawomir Kubik, Lukas Hafner, and David Shore. 2019. \"Sfp1 Regulates Transcriptional Networks Driving Cell Growth and Division through Multiple Promoter-Binding Modes.\" Genes &amp; Development 33 (5\u20136): 288\u2013293.<\/p>\n<p class=\"import-Normal\">Almathen, Faisal, Haitham Elbir, Hussain Bahbahani, Joram Mwacharo, and Olivier Hanotte. 2018. \u201cPolymorphisms in Mc1r and Asip Genes Are Associated with Coat Color Variation in the Arabian Camel.\u201d Journal of Heredity 109 (6): 700\u2013706.<\/p>\n<p class=\"import-Normal\">Ballester, Leomar Y., Rajyalakshmi Luthra, Rashmi Kanagal-Shamanna, and Rajesh R. Singh. 2016. \u201cAdvances in Clinical Next-Generation Sequencing: Target Enrichment and Sequencing Technologies.\u201d Expert Review of Molecular Diagnostics 16 (3): 357\u2013372.<\/p>\n<p class=\"import-Normal\">Baranovskiy, Andrey G., Vincent N. Duong, Nigar D. Babayeva, Yinbo Zhang, Youri I. Pavlov, Karen S. Anderson, and Tahir H. Tahirov. 2018. \u201cActivity and Fidelity of Human DNA Polymerase Alpha Depend on Primer Structure.\u201d Journal of Biological Chemistry 293 (18): 6824\u20136843.<\/p>\n<p>Biswas, S., Ghosh, S., Das, S., &amp; Maitra, S. (2021). Female Reproduction: At the Crossroads of Endocrine Disruptors and Epigenetics. Proceedings of the Zoological Society, 74(4), 532\u2013545. <a href=\"https:\/\/doi.org\/10.1007\/s12595-021-00403-4\">https:\/\/doi.org\/10.1007\/s12595-021-00403-4<\/a><\/p>\n<p class=\"import-Normal\">Brezina, Paulina R., Raymond Anchan, and William G. Kearns. 2016. \u201cPreimplantation Genetic Testing for Aneuploidy: What Technology Should You Use and What Are the Differences?\u201d Journal of Assisted Reproduction and Genetics 33 (7): 823\u2013832.<\/p>\n<p class=\"import-Normal\">Bultman, Scott J. 2017. \u201cInterplay Between Diet, Gut Microbiota, Epigenetic Events, and Colorectal Cancer.\" Molecular Nutrition &amp; Food Research 61 (1):1\u201312.<\/p>\n<p class=\"import-Normal\">Cutting, Garry R. 2015. \u201cCystic Fibrosis Genetics: From Molecular Understanding to Clinical Application.\u201d Nature Reviews Genetics 16 (1): 45\u201356.<\/p>\n<p class=\"import-Normal\">D'Alessandro, Giuseppina., and Fabrizio d'Adda di Fagagna. 2017. \u201cTranscription and DNA Damage: Holding Hands or Crossing Swords?\u201d Journal of Molecular Biology 429 (21): 3215\u20133229.<\/p>\n<p class=\"import-Normal\">De Craene, Johan-Owen, Dimitri L. Bertazzi, S\u00e9verine Bar, and Sylvie Friant. 2017. \u201cPhosphoinositides, Major Actors in Membrane Trafficking and Lipid Signaling Pathways.\u201d International Journal of Molecular Sciences 18 (3): 1\u201320.<\/p>\n<p class=\"import-Normal\">Deng, Lian, and Shuhua Xu. 2018. \u201cAdaptation of Human Skin Color in Various Populations.\u201d Hereditas 155 (1): 1\u201312.<\/p>\n<p class=\"import-Normal\">Dever, Thomas E., Terri G. Kinzy, and Graham D. Pavitt. 2016. \u201cMechanism and Regulation of Protein Synthesis in Saccharomyces Cerevisiae.\u201d Genetics 203 (1): 65\u2013107.<\/p>\n<p class=\"import-Normal\">Eme, Laura, Anja Spang, Jonathan Lombard, Courtney W. Stairs, and Thijs J. G. Ettema. 2017. \u201cArchaea and the Origin of Eukaryotes.\u201d Nature Reviews Microbiology 15 (12): 711\u2013723.<\/p>\n<p class=\"import-Normal\">Gomez-Carballa, Alberto, Jacobo Pardo-Seco, Stefania Brandini, Alessandro Achilli, Ugo A. Perego, Michael D. Coble, Toni M. Diegoli, et al. 2018. \u201cThe Peopling of South America and the Trans-Andean Gene Flow of the First Settlers.\u201d Genome Research 28 (6): 767\u2013779.<\/p>\n<p class=\"import-Normal\">Gvozdenov, Zlata, Janhavi Kolhe, and Brian C. Freeman. 2019. \u201cThe Nuclear and DNA-Associated Molecular Chaperone Network.\u201d Cold Spring Harbour Perspectives in Biology 11 (10): a034009.<\/p>\n<p class=\"import-Normal\">Harkins, Kelly M., and Anne C. Stone. 2015. \u201cAncient Pathogen Genomics: Insights into Timing and Adaptation.\u201d Journal of Human Evolution 79: 137\u2013149.<\/p>\n<p class=\"import-Normal\">Jackson, Maria, Leah Marks, Gerhard H. W. May, and Joanna B. Wilson. 2018. \u201cThe Genetic Basis of Disease.\u201d Essays in Biochemistry 62 (5): 643\u2013723.<\/p>\n<p class=\"import-Normal\">Lenormand, Thomas, Jan Engelstadter, Susan E. Johnston, Erik Wijnker, and Christopher R. Haag. 2016. \u201cEvolutionary Mysteries in Meiosis.\u201d Philosophical Transactions of the Royal Society B 371: 1\u201314.<\/p>\n<p class=\"import-Normal\">Levy, Shawn E., and Richard M. Myers. 2016. \u201cAdvancements in Next-Generation Sequencing.\u201d Annual Review of Genomics and Human Genetics 17: 95\u2013115.<\/p>\n<p class=\"import-Normal\">Lindo, John, Emilia Huerta-S\u00e1nchez, Shigeki Nakagome, Morten Rasmussen, Barbara Petzelt, Joycelynn Mitchell, Jerome S. Cybulski, et al. 2016. \"A Time Transect of Exomes from a Native American Population Before and After European Contact.\" Nature Communications 7: 1\u201311. https:\/\/doi.org\/10.1038\/ncomms13175.<\/p>\n<p class=\"import-Normal\">Lu, Mengfei, Cathryn M. Lewis, and Matthew Traylor. 2017. \u201cPharmacogenetic Testing through the Direct-to-Consumer Genetic Testing Company 23andme.\u201d BMC Medical Genomics 10 (47): 1\u20138.<\/p>\n<p class=\"import-Normal\">Ly, Lundi, Donovan Chan, Mahmoud Aarabi, Mylene Landry, Nathalie A. Behan, Amanda J. MacFarlane, and Jacquetta Trasler. 2017. \u201cIntergenerational Impact of Paternal Lifetime Exposures to Both Folic Acid Deficiency and Supplementation on Reproductive Outcomes and Imprinted Gene Methylation.\u201d Molecular Human Reproduction 23 (7): 461\u2013477.<\/p>\n<p class=\"import-Normal\">Ma, Wenxiu, Giancarlo Bonora, Joel B. Berletch, Xinxian Deng, William S. Noble, and Christine M. Disteche. 2018. \u201cX-Chromosome Inactivation and Escape from X Inactivation in Mouse.\u201d Methods in Molecular Biology 1861: 205\u2013219.<\/p>\n<p class=\"import-Normal\">Machiela, Mitchell J., Weiyin Zhou, Eric Karlins, Joshua N. Sampson, Neal D. 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National Institute of Environmental Health Sciences; United States Government. <a href=\"https:\/\/www.niehs.nih.gov\/health\/topics\/agents\/endocrine\">https:\/\/www.niehs.nih.gov\/health\/topics\/agents\/endocrine<\/a><\/p>\n<p class=\"import-Normal\">Onufriev, Alexey V., and Helmut Schiessel. 2019. \u201cThe Nucleosome: From Structure to Function through Physics.\u201d Current Opinion in Structural Biology 56: 119\u2013130.<\/p>\n<p>Peedicayil J. (2006). Epigenetic therapy--a new development in pharmacology. The Indian journal of medical research, 123(1), 17\u201324.<\/p>\n<p>Pinker, Steven. <em>The Blank Slate: The Modern Denial of Human Nature<\/em>. New York, NY: Penguin Books; 2002. (Comments from Q&amp;A with Pinker on the book, Published 10\/30\/2002 10:21 AM)<\/p>\n<p class=\"import-Normal\">Quillen, Ellen E., Heather L. Norton, Esteban J. Parra, Frida Lona-Durazo, Khai C. Ang, Florin M. Illiescu, Laurel N. 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Cell Death Discovery, 10(1), 1\u201312. https:\/\/doi.org\/10.1038\/s41420-024-01803-z<\/p>\n<p class=\"import-Normal\">Zlotogora, Jo\u00ebl. 2003. \u201cPenetrance and Expressivity in the Molecular Age.\u201d Genetics in Medicine 5 (5): 347\u2013352.<\/p>\n<p class=\"import-Normal\">Zorina-Lichtenwalter, Katerina, Ryan N. Lichtenwalter, Dima V. Zaykin, Marc Parisien, Simon Gravel, Andrey Bortsov, and Luda Diatchenko. 2019. \u201cA Study in Scarlet: MC1R as the Main Predictor of Red Hair and Exemplar of the Flip-Flop Effect.\u201d Human Molecular Genetics 28 (12): 2093-2106.<\/p>\n<p class=\"import-Normal\">Zwart, Haeh. 2018. \u201cIn the Beginning Was the Genome: Genomics and the Bi-Textuality of Human Existence.\u201d New Bioethics 24 (1): 26\u201343.<\/p>\n<\/div>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1695_1848\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1695_1848\"><div tabindex=\"-1\"><div class=\"__UNKNOWN__\">\n<div class=\"textbox\">\n<h6>Student contributors for this chapter from Salinda Hess' ANTH 203: <em>Emma Costa, Shima Gahima, Will Lefebvre, Audrey Ch\u00e9kina\u00ebl.\u00a0<\/em><\/h6>\n<p>Learn more about <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/about-the-authors\/\">authors and editors<\/a>,<a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/student-contributors\/\"> Hess' student contributions<\/a>, and <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/versioning-history\/\">versioning history<\/a>.<\/p>\n<\/div>\n<\/div>\n<div class=\"__UNKNOWN__\">\n<div class=\"textbox textbox--learning-objectives\">\n<header class=\"textbox__header\">\n<h2 class=\"textbox__title\">Learning Objectives<\/h2>\n<\/header>\n<div class=\"textbox__content\">\n<ul>\n<li class=\"import-Normal\">Explain and identify the purpose of both DNA replication and the cell cycle.<\/li>\n<li class=\"import-Normal\">Identify key differences between mitosis and meiosis.<\/li>\n<li class=\"import-Normal\">Outline the process of protein synthesis, including transcription and translation.<\/li>\n<li class=\"import-Normal\">Use principles of Mendelian inheritance to predict genotypes and phenotypes of future generations.<\/li>\n<li class=\"import-Normal\">Explain complexities surrounding patterns of genetic inheritance and polygenic traits.<\/li>\n<li class=\"import-Normal\">Discuss challenges to and bioethical concerns of genetic testing.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<h2 class=\"import-Normal\">Cells and Molecules<\/h2>\n<h3 class=\"import-Normal\">Molecules of Life<\/h3>\n<p class=\"import-Normal\">All organisms are composed of four basic types of molecules that are essential for cell structure and function: proteins<strong>, <\/strong>lipids<strong>, <\/strong>carbohydrates, and nucleic acids (Figure 4.1). <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_586\">Proteins<\/a> <\/strong>are crucial for cell shape and nearly all cellular tasks, including receiving signals from outside the cell and mobilizing intra-cellular responses. <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_588\">Lipids<\/a> <\/strong>are a class of organic compounds that include fats, oils, and hormones.\u00a0<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_590\">Carbohydrates<\/a><\/strong> are sugar molecules and serve as energy to cells in the form of glucose. Lastly, <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_592\">nucleic acids<\/a><\/strong>, including <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_594\">deoxyribonucleic acid (DNA)<\/a><\/strong>, carry genetic information about a living organism.<\/p>\n<table class=\"aligncenter\" style=\"width: 740px;height: 551px\" border=\"1pt solid rgb(0, 0, 0)\" cellpadding=\"5pt\">\n<caption>Figure 4.1: Information about the four biomolecules. Credit: Biomolecules Table original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Hayley Mann is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/ target=\">CC BY-NC 4.0 License<\/a>.<\/caption>\n<thead>\n<tr style=\"height: 40px\">\n<td class=\"a-C\" style=\"background-color: transparent;padding: 5pt;border: 1pt solid #000000;width: 125.594px;height: 40px\">\n<p class=\"import-Normal\"><strong>Molecule<\/strong><\/p>\n<\/td>\n<td class=\"a-C\" style=\"background-color: transparent;padding: 5pt;border: 1pt solid #000000;width: 223.906px;height: 40px\">\n<p class=\"import-Normal\" style=\"margin-left: 36pt\"><strong>Definition<\/strong><\/p>\n<\/td>\n<td class=\"a-C\" style=\"background-color: transparent;padding: 5pt;border: 1pt solid #000000;width: 346.562px;height: 40px\">\n<p class=\"import-Normal\" style=\"margin-left: 36pt\"><strong>Example<\/strong><\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"a-R\" style=\"height: 194px\">\n<td class=\"a-C\" style=\"background-color: transparent;padding: 5pt;border: 1pt solid #000000;width: 125.594px;height: 194px\">\n<p class=\"import-Normal\">Proteins<\/p>\n<\/td>\n<td class=\"a-C\" style=\"background-color: transparent;padding: 5pt;border: 1pt solid #000000;width: 223.906px;height: 194px\">\n<p class=\"import-Normal\">Composed of one or more long chains of amino acids (i.e., basic units of protein)<\/p>\n<p class=\"import-Normal\">Often folded into complex 3D shapes that relate to function<\/p>\n<p class=\"import-Normal\">Proteins interact with other types of proteins and molecules<\/p>\n<\/td>\n<td class=\"a-C\" style=\"background-color: transparent;padding: 5pt;border: 1pt solid #000000;width: 346.562px;height: 194px\">\n<p class=\"import-Normal\">Proteins come in different categories including structural (e.g., collagen, keratin, lactase, hemoglobin, cell membrane proteins), defense proteins (e.g, antibodies), enzymes (e.g., lactase), hormones (e.g., insulin), and motor proteins (e.g., actin)<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a-R\" style=\"height: 137px\">\n<td class=\"a-C\" style=\"background-color: transparent;padding: 5pt;border: 1pt solid #000000;width: 125.594px;height: 137px\">\n<p class=\"import-Normal\">Lipids<\/p>\n<\/td>\n<td class=\"a-C\" style=\"background-color: transparent;padding: 5pt;border: 1pt solid #000000;width: 223.906px;height: 137px\">\n<p class=\"import-Normal\">Insoluble in water due to hydrophilic (water-loving) head and a hydrophobic (water-repelling) tail<\/p>\n<\/td>\n<td class=\"a-C\" style=\"background-color: transparent;padding: 5pt;border: 1pt solid #000000;width: 346.562px;height: 137px\">\n<p class=\"import-Normal\">Fats, such as triglycerides, store energy for your body<\/p>\n<p class=\"import-Normal\">Steroid hormones (e.g., estrogen and testosterone) act as chemical messengers to communicate between cells and tissues, as well as biochemical pathways inside of the cell<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a-R\" style=\"height: 80px\">\n<td class=\"a-C\" style=\"background-color: transparent;padding: 5pt;border: 1pt solid #000000;width: 125.594px;height: 80px\">\n<p class=\"import-Normal\">Carbohydrates<\/p>\n<\/td>\n<td class=\"a-C\" style=\"background-color: transparent;padding: 5pt;border: 1pt solid #000000;width: 223.906px;height: 80px\">\n<p class=\"import-Normal\">Large group of organic molecules that are composed of carbon and hydrogen atoms<\/p>\n<\/td>\n<td class=\"a-C\" style=\"background-color: transparent;padding: 5pt;border: 1pt solid #000000;width: 346.562px;height: 80px\">\n<p class=\"import-Normal\">Starches and sugars, including blood glucose, provide cells with energy<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a-R\" style=\"height: 78px\">\n<td class=\"a-C\" style=\"background-color: transparent;padding: 5pt;border: 1pt solid #000000;width: 125.594px;height: 78px\">\n<p class=\"import-Normal\">Nucleic Acids<\/p>\n<\/td>\n<td class=\"a-C\" style=\"background-color: transparent;padding: 5pt;border: 1pt solid #000000;width: 223.906px;height: 78px\">\n<p class=\"import-Normal\">Carries the genetic information of an organism<\/p>\n<\/td>\n<td class=\"a-C\" style=\"background-color: transparent;padding: 5pt;border: 1pt solid #000000;width: 346.562px;height: 78px\">\n<p class=\"import-Normal\">DNA<\/p>\n<p class=\"import-Normal\">RNA<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h3 class=\"import-Normal\">Cells<\/h3>\n<p class=\"import-Normal\">In 1665, Robert Hooke observed slices of plant cork using a microscope. Hooke noted that the microscopic plant structures he saw resembled <em>cella,<\/em> meaning \u201ca small room\u201d in Latin. Approximately two centuries later, biologists recognized the cell as being the most fundamental unit of life and that all life is composed of cells. Cellular organisms can be characterized as two main cell types: <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_596\">prokaryotes<\/a><\/strong> and <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_598\">eukaryotes<\/a> <\/strong>(Figure 4.2).<\/p>\n<figure id=\"attachment_77-3\" aria-describedby=\"caption-attachment-77-3\" style=\"width: 468px\" class=\"wp-caption alignleft\"><a href=\"\/explorationsclone\/part\/figure-3-2\/\" target=\"_blank\" rel=\"noopener\"><img class=\"wp-image-70\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2023\/06\/cellsfinal-scaled-1.jpg\" alt=\"Prokaryote and eukaryote cells. A full text description of this image is available using link in the caption.\" width=\"468\" height=\"370\" \/><\/a><figcaption id=\"caption-attachment-77-3\" class=\"wp-caption-text\">Figure 4.2: Prokaryotic cell and eukaryotic cell. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available.<\/a> Credit: Prokaryote vs. eukaryote original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Mary Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Prokaryotes include bacteria and archaea, and they are composed of a single cell. Additionally, their DNA and <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_600\">organelles<\/a><\/strong> are not surrounded by individual membranes. Thus, no compartments separate their DNA from the rest of the cell (see Figure 4.2). It is well known that some bacteria can cause illness in humans. For instance, <em>Escherichia coli<\/em> (<em>E. coli<\/em>) and <em>Salmonella<\/em> contamination can result in food poisoning symptoms. Pneumonia and strep throat are caused by <em>Streptococcal<\/em> bacteria. <em>Neisseria gonorrhoeae<\/em> is a sexually transmitted bacterial disease. Although bacteria are commonly associated with illness, not all bacteria are harmful. For example, researchers are studying the relationship between the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_602\">microbiome<\/a> <\/strong>and human health. The bacteria that are part of the healthy human microbiome perform beneficial roles, such as digesting food, boosting the immune system, and even making vitamins (e.g., B12 and K).<\/p>\n<p class=\"import-Normal\">Eukaryotes can be single-celled or multi-celled in their body composition. In contrast to prokaryotes, eukaryotes possess membranes that surround their DNA and organelles. An example of a single-celled eukaryote is the microscopic algae found in ponds (phytoplankton), which can produce oxygen from the sun. Yeasts are also single-celled, and fungi can be single- or multicellular. Plants and animals are all multicellular.<\/p>\n<p class=\"import-Normal\">Although plant and animal cells have a surprising number of similarities, there are some key differences (Figure 4.3). For example, plant cells possess a thick outer cell membrane made of a fibrous carbohydrate called cellulose. Animal and plant cells also have different <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_604\">tissues<\/a><\/strong>. For most plants, the outermost layer of cells forms a waxy cuticle that helps to protect the cells and to prevent water loss. Humans have skin, which is the outermost cell layer that is predominantly composed of a tough protein called keratin. Overall, humans have a diversity of tissue types (e.g., cartilage, brain, and heart).<\/p>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_77-4\" aria-describedby=\"caption-attachment-77-4\" style=\"width: 2560px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-71 size-full\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/3.x3ai-01-scaled-1.jpg\" alt=\"Plant and animal cells. A full text description of this image is available using link in the caption.\" width=\"2560\" height=\"1162\" \/><figcaption id=\"caption-attachment-77-4\" class=\"wp-caption-text\">Figure 4.3: Plant cell compared to an animal cell. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available.<\/a> Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Simple_plant_and_animal_cell.svg\" target=\"_blank\">Simple plant and animal cell<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Nefronus\" target=\"_blank\">Tom\u00e1\u0161 Kebert<\/a> &amp; <a href=\"https:\/\/www.umimeto.org\/\" target=\"_blank\">umimeto.org<\/a> has been modified (labels added) and is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\" target=\"_blank\">CC BY-NC-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<h3 class=\"import-Normal\"><strong>Animal Cell Organelles<\/strong><\/h3>\n<p class=\"import-Normal\">An animal cell is surrounded by a double membrane called the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_606\">phospholipid bilayer<\/a> <\/strong>(Figure 4.4). A closer look reveals that this protective barrier is made of lipids and proteins that provide structure and function for cellular activities, such as regulating the passage of molecules and ions (e.g., H<sub>2<\/sub>O and sodium) into and out of the cell. <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_608\">Cytoplasm<\/a><\/strong> is the jelly-like matrix inside of the cell membrane. Part of the cytoplasm comprises organelles, which perform different specialized tasks for the cell (Figure 4.5). An example of an organelle is the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_610\">nucleus<\/a><\/strong>, where the cell\u2019s DNA is located.<\/p>\n<p>&nbsp;<\/p>\n<figure style=\"width: 555px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image1.png\" alt=\"Cell wall of a phospholipid bilayer with embedded channels, carbohydrates, and proteins.\" width=\"555\" height=\"270\" \/><figcaption class=\"wp-caption-text\">Figure 4.4: A phospholipid bilayer with membrane-bound carbohydrates and proteins. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available.<\/a> Credit: <a href=\"https:\/\/openstax.org\/books\/anatomy-and-physiology\/pages\/3-1-the-cell-membrane#fig-ch03_01_03\" target=\"_blank\">Cell Membrane (Anatomy &amp; Physiology, Figure 3.4)<\/a> by<a href=\"https:\/\/openstax.org\/\"> OpenStax<\/a> is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\" target=\"_blank\"> CC BY 4.0 License<\/a>.<\/figcaption><\/figure>\n<figure style=\"width: 547px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image1-1.png\" alt=\"Animal cell with various organelles labeled.\" width=\"547\" height=\"415\" \/><figcaption class=\"wp-caption-text\">Figure 4.5: An animal cell with membrane-enclosed organelles. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available.<\/a> Credit: <a href=\"https:\/\/www.genome.gov\/genetics-glossary\/Organelle?id=147\" target=\"_blank\">Organelle<\/a> by<a href=\"https:\/\/www.genome.gov\/\" target=\"_blank\"> NIH National Human Genome Research Institute<\/a> is in the<a href=\"https:\/\/www.genome.gov\/about-nhgri\/Policies-Guidance\/Copyright\" target=\"_blank\"> public domain<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Another organelle is the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_612\">mitochondrion<\/a><\/strong>. Mitochondria are often referred to as \u201cpowerhouse centers\u201d because they produce energy for the cell in the form of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_616\">adenosine triphosphate (ATP)<\/a><\/strong>. Depending on the species and tissue type, multicellular eukaryotes can have hundreds to thousands of mitochondria in each of their cells. Scientists have determined that mitochondria were once <em>symbiotic<\/em> prokaryotic organisms (i.e., helpful bacteria) that transformed into cellular organelles over time. This evolutionary explanation helps explain why mitochondria also have their own DNA, called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_618\">mitochondrial DNA (mtDNA)<\/a><\/strong>. All organelles have important physiological functions and disease can occur when organelles do not perform their role optimally. Figure 4.6 lists other organelles found in the cell and their specialized cellular roles.<\/p>\n<table class=\"aligncenter\" style=\"width: 399pt\" border=\"1pt solid rgb(0, 0, 0)\" cellpadding=\"5pt\">\n<caption>Figure 4.6: This table depicts the names of organelles and their cellular functions. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-9\/\" target=\"_blank\">Cell Structure table (Figure 3.11)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Hayley Mann, Xazmin Lowman, and Malaina Gaddis is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/caption>\n<thead>\n<tr>\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Cell structure<\/strong><\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Description<\/strong><\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"a0-R\" style=\"height: 36pt\">\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Centrioles<\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Assist with the organization of mitotic spindles, which extend and contract for the purpose of cellular movement during mitosis and meiosis.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a0-R\" style=\"height: 36pt\">\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Cytoplasm<\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Gelatinous fluid located inside of cell membrane that contains organelles.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a0-R\" style=\"height: 24pt\">\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Endoplasmic reticulum (ER)<\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Continuous membrane with the nucleus that helps transport, synthesize, modify, and fold proteins. Rough ER has embedded ribosomes, whereas smooth ER lacks ribosomes.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a0-R\" style=\"height: 24pt\">\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Golgi body<\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Layers of flattened sacs that receive and transmit messages from the ER to secrete and transport proteins within the cell.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a0-R\" style=\"height: 24pt\">\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Lysosome<\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Located in the cytoplasm; contains enzymes to degrade cellular components.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a0-R\" style=\"height: 24pt\">\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Microtubule<\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Involved with cellular movement including intracellular transport and cell division.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a0-R\" style=\"height: 24pt\">\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Mitochondrion<\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Responsible for cellular respiration, where energy is produced by converting nutrients into ATP.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a0-R\" style=\"height: 24pt\">\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Nucleolus<\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Resides inside of the nucleus and is the site of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_620\">ribosomal RNA (rRNA)<\/a><\/strong> transcription, processing, and assembly.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a0-R\" style=\"height: 24pt\">\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Nucleopore<\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Pores in the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_622\">nuclear envelope<\/a><\/strong> that are selectively permeable.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a0-R\">\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Nucleus<\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Contains the cell\u2019s DNA and is surrounded by the nuclear envelope.<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a0-R\">\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Ribosome<\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Located in the cytoplasm and also the membrane of the rough endoplasmic reticulum. Messenger RNA (mRNA) binds to ribosomes and proteins are synthesized.<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h2 class=\"import-Normal\">Introduction to Genetics<\/h2>\n<p class=\"import-Normal\">Genetics is the study of heredity. Biological parents pass down their genetic traits to their offspring. Although children resemble their parents, genetic traits often vary in appearance or molecular function. For example, two parents with normal color vision can sometimes produce a son with red-green colorblindness. <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_624\">Molecular geneticists<\/a> <\/strong>study the biological mechanisms responsible for creating variation between individuals, such as DNA <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_626\">mutations<\/a><\/strong> (see Chapter 5), cell division, and genetic regulation.<\/p>\n<p class=\"import-Normal\"><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_628\">Molecular anthropologists<\/a><\/strong> use genetic data to test anthropological questions. Some of these anthropologists utilize <strong>ancient DNA (aDNA)<\/strong>, which is DNA that is extracted from anything once living, including human, animal, and plant remains. Over time, DNA becomes degraded (i.e., less intact), but specialized laboratory techniques can make copies of short degraded aDNA segments, which can then be reassembled to provide more complete DNA information.<\/p>\n<h3 class=\"import-Normal\"><strong>DNA Structure<\/strong><\/h3>\n<p class=\"import-Normal\">The discovery, in 1953, of the molecular structure of deoxyribonucleic acid (DNA) was one of the greatest scientific achievements of all time. Using X-ray crystallography, Rosalind Franklin (Figure 4.7) provided an image that clearly showed the double helix shape of DNA. Due to controversy, Franklin\u2019s colleagues received more recognition for the DNA discovery. In 1962, Watson, Crick, and Wilkins won the Nobel Prize, while Franklin, who had died in 1958, was not honoured. Today, her vital contributions and scientific skill are widely recognized.<\/p>\n<figure style=\"width: 223px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image2-1.png\" alt=\"Historic photo of woman looking into a microscope.\" width=\"223\" height=\"268\" \/><figcaption class=\"wp-caption-text\">Figure 4.7: Chemist and X-ray crystallographer Rosalind Franklin. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Rosalind_Franklin.jpg\" target=\"_blank\">Rosalind Franklin<\/a> from the personal collection of Jenifer Glynn by MRC Laboratory of Molecular Biology is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\" target=\"_blank\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">The double helix shape of DNA can be described as a twisted ladder (Figure 4.8). More specifically, DNA is a double-stranded molecule with its two strands oriented in opposite directions (i.e., antiparallel). Each strand is composed of <strong>nucleotides <\/strong>with a<strong> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_634\">sugar phosphate backbone<\/a><\/strong>. There are four different types of DNA nucleotides: adenine (A), thymine (T), cytosine (C), and guanine (G). The two DNA strands are held together by nucleotide <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_636\">base pairs<\/a><\/strong>, which have chemical bonding rules. The complementary base-pairing rules are as follows: A and T bond with each other, while C and G form a bond. The chemical bonds between A-T and C-G are formed by \u201cweak\u201d hydrogen atom interactions, which means the two strands can be easily separated. A DNA sequence is the order of nucleotide bases (A, T, G, C) along only one DNA strand. If one DNA strand has the sequence CATGCT, then the other strand will have a complementary sequence GTACGA. This is an example of a short DNA sequence. In reality, there are approximately three billion DNA base pairs in human cells.<\/p>\n<figure style=\"width: 341px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image3.jpg\" alt=\"Double helix structure of DNA.\" width=\"341\" height=\"400\" \/><figcaption class=\"wp-caption-text\">Figure 4.8: Structural components that form double-stranded nucleic acid (DNA). Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Difference_DNA_RNA-EN.svg\" target=\"_blank\">Difference DNA RNA-EN<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Sponk\" target=\"_blank\">Sponk<\/a> (translation by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Sponk\" target=\"_blank\">Sponk<\/a>, cropped by Katie Nelson) is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\" target=\"_blank\">CC BY-NC-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<h3 class=\"import-Normal\"><strong>DNA Is Highly Organized within the Nucleus<\/strong><\/h3>\n<p class=\"import-Normal\">If you removed the DNA from a single human cell and stretched it out completely, it would measure approximately two meters (about 6.5 feet). Therefore, DNA molecules must be compactly organized in the nucleus. To achieve this, the double helix configuration of DNA undergoes coiling. An analogy would be twisting a string until coils are formed and then continuing to twist so that secondary coils are formed, and so on. To assist with coiling, DNA is first wrapped around proteins called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_638\">histones<\/a><\/strong>. This creates a complex called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_640\">chromatin<\/a>,<\/strong> which resembles \u201cbeads on a string\u201d (Figure 4.9). Next, chromatin is further coiled into a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_642\">chromosome<\/a><\/strong>. Another important feature of DNA is that chromosomes can be altered from tightly coiled (chromatin) to loosely coiled (<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_644\">euchromatin<\/a><\/strong>). Most of the time, chromosomes in the nucleus remain in a euchromatin state so that DNA sequences are accessible for regulatory processes to occur.<\/p>\n<p>&nbsp;<\/p>\n<figure style=\"width: 558px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image1-2.png\" alt=\"Illustrates how chromosomes are made up of various components. \" width=\"558\" height=\"534\" \/><figcaption class=\"wp-caption-text\">Figure 4.9: The hierarchical organization of chromosomes. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available<\/a>.\u00a0Credit: <a href=\"https:\/\/www.genome.gov\/glossary\/index.cfm?id=102\" target=\"_blank\">Histone (2019)<\/a> by<a href=\"https:\/\/www.genome.gov\/\" target=\"_blank\"> NIH National Human Genome Research Institute<\/a> is in the<a href=\"https:\/\/www.genome.gov\/about-nhgri\/Policies-Guidance\/Copyright\" target=\"_blank\"> public domain<\/a>.<\/figcaption><\/figure>\n<figure style=\"width: 256px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image4-1.png\" alt=\"Chromatid is divided into a short and long arm, bound by a centromere. \" width=\"256\" height=\"296\" \/><figcaption class=\"wp-caption-text\">Figure 4.10: The regions of a chromosome. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-9\/\" target=\"_blank\">Chromosome (Figure 3.16)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Katie Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<\/div>\n<p>&nbsp;<\/p>\n<div class=\"__UNKNOWN__\">\n<p>Human body cells typically have 23 pairs of chromosomes, for a total of 46 chromosomes in each cell\u2019s nucleus. An interesting fact is that the number of chromosomes an organism possesses varies by species, and this figure is not dependent upon the size or complexity of the organism. For instance, chimpanzees have a total of 48 chromosomes, while hermit crabs have 254. Chromosomes also have a distinct physical structure, including <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_646\">centromeres<\/a> <\/strong>(the \u201ccenter\u201d) and <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_648\">telomeres<\/a> <\/strong>(the ends) (Figure 4.10). Because of the centromeric region, chromosomes are described as having two different \u201carms,\u201d where one arm is long and the other is shorter. Centromeres play an important role during cell division, which will be discussed in the next section. Telomeres are located at the ends of chromosomes; they help protect the chromosomes from degradation after every round of cell division.<\/p>\n<\/div>\n<p>&nbsp;<\/p>\n<div class=\"__UNKNOWN__\">\n<div class=\"textbox\">\n<h2 class=\"import-Normal\">Special Topic: First Nation Immunity and European Diseases\u2014A Study of Ancient DNA<\/h2>\n<figure style=\"width: 300px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image5-1.png\" alt=\"A group of people in historic clothing, some with traditional shawls, eat under a tent.\" width=\"300\" height=\"184\" \/><figcaption class=\"wp-caption-text\">Figure 4.11a: Tsimshian Native Americans of the Pacific Northwest Coast. Credit: <a href=\"https:\/\/central.bac-lac.gc.ca\/.redirect?app=fonandcol&amp;id=3368729&amp;lang=eng\" target=\"_blank\">A group of Tsimshian people having a tea party in a tent, Lax Kw'alaams (formerly Port Simpson), B.C., c. 1890<\/a> by unknown photographer is in the <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/pdm\" target=\"_blank\">Public Domain<\/a>. This image is available from the <a href=\"https:\/\/www.bac-lac.gc.ca\/eng\/Pages\/home.aspx\" target=\"_blank\">Library and Archives Canada<\/a>, item number 3368729.<\/figcaption><\/figure>\n<p>Beginning in the early fifteenth century, First Nations progressively suffered from high mortality rates as the result of colonization from foreign powers. European-borne diseases such as measles, tuberculosis, influenza, and smallpox are largely responsible for the population collapse of Indigenous peoples in the Americas. Many Europeans who immigrated to the Americas had lived in large sedentary populations, which also included coexisting with domestic animals and pests. Although a few prehistoric Indigenous populations can be characterized as large agricultural societies (especially in Mesoamerica), their overall culture, community lifestyle, and subsistence practices were markedly different from that of Europeans. Therefore, because they did not share the same urban living environments as Europeans, it is believed that Indigenous peoples were susceptible to many European diseases.<\/p>\n<figure style=\"width: 459px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image6.jpg\" alt=\"Tsimshian territory on the coast of British Columbia next to the Hecate Strait.\" width=\"459\" height=\"594\" \/><figcaption class=\"wp-caption-text\">Figure 4.11b: Tsimshian territory in present-day British Columbia. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-9\/\" target=\"_blank\">Tsimshian Territory map (Figure 3.12b)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Elyssa Ebding at<a href=\"https:\/\/www.csuchico.edu\/geop\/geoplace\/index.shtml\" target=\"_blank\"> GeoPlace, California State University, Chico<\/a> is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\"> CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p>In 2016, a <em>Nature<\/em> article published by John Lindo and colleagues was the first to investigate whether pre-contact Indigenous peoples possessed a genetic susceptibility to European diseases. Their study included Tsimshians, a First Nation community from British Columbia (Figure 4.11a-b). DNA from both present-day and ancient individuals (who lived between 500 and 6,000 years ago) was analysed. The research team discovered that a change occurred in the <em>HLA-DQA1<\/em> gene, which is a member of the major histocompatibility complex (MHC) immune system molecules. MHC molecules are responsible for detecting and triggering an immune response against pathogens. Lindo and colleagues (2016) concluded that <em>HLA-DQA1<\/em> gene helped Indigenous peoples adapt to their local environmental ecology. However, when European-borne epidemics occurred in the Northwest during the 1800s, a certain <em>HLA-DQA1<\/em> <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_650\">DNA sequence<\/a><\/strong> variant (allele) associated with ancient Tsimshian immunity was no longer adaptive. As the result of past selective pressures from European diseases, present-day Tsimshians have different <em>HLA-DQA1<\/em> allele frequencies. The precise role that <em>HLA-DQA1 <\/em>plays in immune adaptation requires further investigation. But overall, this study serves as an example of how studying ancient DNA from the remains of deceased individuals can help provide insight into living human populations and historical events.<\/p>\n<\/div>\n<h2 class=\"import-Normal\">DNA Replication and Cell Division<\/h2>\n<p class=\"import-Normal\">For life to continue and flourish, cells must be able to divide. Tissue growth and cellular damage repair are also necessary to maintain an organism throughout its life. All these rely on the dynamic processes of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_652\">DNA replication<\/a><\/strong> and the <strong>cell cycle<\/strong>. The mechanisms highlighted in this section are tightly regulated and represent only part of the life cycle of a cell.<\/p>\n<h3 class=\"import-Normal\"><strong>DNA Replication <\/strong><\/h3>\n<p class=\"import-Normal\">DNA replication is the process by which new DNA is copied from an original DNA template. It is one phase of the highly coordinated cell cycle, and it requires a variety of enzymes with special functions. The creation of a complementary DNA strand from a template strand is described as <strong>semi-conservative replication<\/strong>. The result of semi-conservative replication is two separate double-stranded DNA molecules, each of which is composed of an original \u201cparent\u201d template strand and a newly synthesized \u201cdaughter\u201d DNA strand.<\/p>\n<p class=\"import-Normal\">DNA replication progresses in three steps referred to as <strong>initiation<\/strong>, <strong>elongation,<\/strong> and <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_662\">termination<\/a><\/strong>. During initiation, enzymes are recruited to specific sites along the DNA sequence (Figure 4.12). For example, an initiator enzyme, called <strong>helicase<\/strong>, \u201cunwinds\u201d DNA by breaking the hydrogen bonds between the two parent strands. The unraveling of the helix into two separated strands exposes the strands and creates a fork, which is the active site of DNA replication.<\/p>\n<figure style=\"width: 580px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image7.jpg\" alt=\"Helicase enzyme splits apart 2 DNA strands. On each strand DNA polymerase matches free nucleotides.\" width=\"580\" height=\"359\" \/><figcaption class=\"wp-caption-text\">Figure 4.12: DNA replication and the different enzymes associated with it. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available<\/a>. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:0323_DNA_Replication.jpg\" target=\"_blank\">0323 DNA Replication<\/a> by <a href=\"https:\/\/openstax.org\/books\/anatomy-and-physiology\/pages\/1-introduction\" target=\"_blank\">OpenStax<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/legalcode\" target=\"_blank\">CC BY 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Elongation is the assembly of new DNA daughter strands from the exposed original parent strands. The two parent strands can further be classified as <strong>leading strand<\/strong> or <strong>lagging strand<\/strong> and are distinguished by the direction of replication. Enzymes called <strong>DNA polymerases<\/strong> read parent template strands in a specific direction. Complementary nucleotides are added, and the newly formed daughter strands will grow. On the leading parent strand, a DNA polymerase will create one continuous strand. The lagging parent strand is created in several disconnected sections and other enzymes fill in the missing nucleotide gaps between these sections.<\/p>\n<p class=\"import-Normal\">Finally, termination refers to the end of DNA replication activity. It is signaled by a stop sequence in the DNA that is recognized by machinery at the replication fork. The end result of DNA replication is that the number of chromosomes are doubled so that the cell can divide into two.<\/p>\n<h3 class=\"import-Normal\"><strong>DNA Mutations<\/strong><\/h3>\n<p class=\"import-Normal\">DNA replication should result in the creation of two identical DNA nucleotide sequences. However, although DNA polymerases are quite precise during DNA replication, copying mistakes are estimated to occur every 10<sup>7<\/sup> DNA nucleotides. Variation from the original DNA sequence is known as a mutation (Refer to Chapter 5). Briefly, mutations can result in single-nucleotide changes, as well as the insertion or deletion of nucleotides and repeated sequences. Depending on where they occur in the genome, mutations can be <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_672\">deleterious<\/a> <\/strong>(harmful). For example, mutations may occur in regions that control cell cycle regulation, which can result in cancer (see Special Topic: The Cell Cycle and Immortality of Cancer Cells). Many other types of mutations, however, are not harmful to an organism.<\/p>\n<p class=\"import-Normal\">Regardless of their effect, the cell attempts to reduce the frequency of mutations that occur during DNA replication. To accomplish this, there are polymerases with proofreading capacities that can identify and correct mismatched nucleotides. These safeguards reduce the frequency of DNA mutations so that they only occur every 10<sup>9<\/sup> nucleotides.<\/p>\n<h3 class=\"import-Normal\"><strong>Mitotic Cell Division<\/strong><\/h3>\n<p class=\"import-Normal\">There are two types of cells in the body: <strong>germ cells <\/strong>(sperm and egg) and <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_676\">somatic cells<\/a><\/strong>. The body and its various tissues comprises somatic cells. Organisms that contain two sets of chromosomes in their somatic cells are called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_678\">diploid<\/a><\/strong> organisms. Humans have 46 chromosomes and they are diploid because they inherit one set of chromosomes (<em>n <\/em>= 23) from each parent. As a result, they have 23 matching pairs of chromosomes, which are known as <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_680\">homologous chromosomes<\/a><\/strong>. As seen in Figure 4.13, homologous chromosome pairs vary in size and are generally numbered from largest (chromosome 1) to smallest (chromosome 22) with the exception of the 23rd pair, which is made up of the sex chromosomes (X and Y). Typically, the female sex is XX and the male sex is XY. Individuals inherit an X chromosome from their chromosomal mother and an X or Y from their chromosomal father.<\/p>\n<figure id=\"attachment_81-2\" aria-describedby=\"caption-attachment-81-2\" style=\"width: 468px\" class=\"wp-caption alignleft\"><img class=\"wp-image-81\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/Karyotype.jpg\" alt=\"Karyotype showing pairs of chromosomes organized by size into 23 pairs.\" width=\"468\" height=\"263\" \/><figcaption id=\"caption-attachment-81-2\" class=\"wp-caption-text\">Figure 4.13: The 23 human chromosome pairs. Credit: Genome (2019) by NIH National Human Genome Research Institute is in the public domain.<\/figcaption><\/figure>\n<p class=\"import-Normal\">To grow and repair tissues, somatic cells must divide. As discussed previously, for cell division to occur, a cell must first replicate its genetic material. During DNA replication, each chromosome produces double the amount of genetic information. The duplicated arms of chromosomes are known as <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_682\">sister chromatids<\/a>,<\/strong> and they are attached at the centromeric region. To elaborate, the number of chromosomes stays the same (<em>n<\/em> = 46); however, the amount of genetic material is doubled in the cell as the result of replication.<\/p>\n<p class=\"import-Normal\"><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_684\">Mitosis<\/a><\/strong> is the process of somatic cell division that gives rise to two diploid daughter cells (Figure 4.14). Once DNA and other organelles in the cell have finished replication, mitotic spindle fibres physically align each chromosome at the center of the cell. Next, the spindle fibres divide the sister chromatids and move each one to opposite sides of the cell. At this phase, there are 46 chromosomes on each side of a human cell. The cell can now divide into two fully separated daughter cells.<\/p>\n<\/div>\n<figure id=\"attachment_88-3\" aria-describedby=\"caption-attachment-88-3\" style=\"width: 569px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-82\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/mitosismeiosisNEW.jpg\" alt=\"The stages of mitosis and meiosis.\" width=\"569\" height=\"521\" \/><figcaption id=\"caption-attachment-88-3\" class=\"wp-caption-text\">Figure 4.14: The steps of mitotic cell division and meiotic cell division. Credit: Mitosis and meiosis original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Katie Nelson is a collective work under a CC BY-NC 4.0 License. [Includes Mitosis (Figure 3.20) and Meiosis (Figure 3.21) by Mary Nelson; CC BY-NC 4.0 License.]<\/figcaption><\/figure>\n<div class=\"__UNKNOWN__\">\n<h3 class=\"import-Normal\"><strong>Meiotic Cell Division<\/strong><\/h3>\n<p class=\"import-Normal\">Gametogenesis is the production of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_686\">gametes<\/a><\/strong> (sperm and egg cells); it involves two rounds of cell division called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_688\">meiosis<\/a><\/strong>. Similar to mitosis, the parent cell in meiosis is diploid. However, meiosis has a few key differences, including the number of daughter cells produced (four cells, which require two rounds of cell division to produce) and the number of chromosomes each daughter cell has (see Figure 4.14).<\/p>\n<p class=\"import-Normal\">During the first round of division (known as meiosis I), each chromosome (<em>n<\/em> = 46) replicates its DNA so that sister chromatids are formed. Next, with the help of spindle fibres, homologous chromosomes align near the center of the cell and sister chromatids physically swap genetic material. In other words, the sister chromatids of matching chromosomes cross over with each other at matching DNA nucleotide positions. The occurrence of homologous chromosomes crossing over, swapping DNA, and then rejoining segments is called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_690\">genetic recombination<\/a><\/strong>. The \u201cgenetic shuffling\u201d that occurs in gametes increases organismal genetic diversity by creating new combinations of genes on chromosomes that are different from the parent cell. Genetic mutations can also arise during recombination. For example, there may be an unequal swapping of genetic material that occurs between the two sister chromatids, which can result in deletions or duplications of DNA nucleotides. Once genetic recombination is complete, homologous chromosomes are separated and two daughter cells are formed.<\/p>\n<p class=\"import-Normal\">The daughter cells after the first round of meiosis are <strong>haploid<\/strong>, meaning they only have one set of chromosomes (<em>n <\/em>= 23). During the second round of cell division (known as meiosis II), sister chromatids are separated and two additional haploid daughter cells are formed. Therefore, the four resulting daughter cells have one set of chromosomes (<em>n<\/em> = 23), and they also have a genetic composition that is not identical to the parent cells nor to each other.<\/p>\n<p class=\"import-Normal\">Although both sperm and egg gamete production undergo meiosis, they differ in the final number of viable daughter cells. In the case of spermatogenesis, four mature sperm cells are produced. Although four egg cells are also produced in oogenesis, only one of these egg cells will result in an ovum (mature egg). During fertilization, an egg cell and sperm cell fuse, which creates a diploid cell that develops into an embryo. The ovum also provides the cellular organelles necessary for embryonic cell division. This includes mitochondria, which is why humans, and most other multicellular eukaryotes, have the same mtDNA sequence as their mothers.<\/p>\n<h3 class=\"import-Normal\"><strong>Chromosomal Disorders: Aneuploidies<\/strong><\/h3>\n<p class=\"import-Normal\">During mitosis or meiosis, entire deletions or duplications of chromosomes can occur due to error. For example, homologous chromosomes may fail to separate properly, so one daughter cell may end up with an extra chromosome while the other daughter cell has one less. Cells with an unexpected (or abnormal) number of chromosomes are known as <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_694\">aneuploid<\/a><\/strong>. Adult or embryonic cells can be tested for chromosome number (<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_696\">karyotyping<\/a><\/strong>). Aneuploid cells are typically detrimental to a dividing cell or developing embryo, which can lead to a loss of pregnancy. However, the occurrence of individuals being born with three copies of the 21st chromosome is relatively common; this genetic condition is known as Down Syndrome. Moreover, individuals can also be born with aneuploid sex chromosome conditions such as XXY, XXX, and XO (referring to only one X chromosome).<\/p>\n<div class=\"textbox\">\n<h2 class=\"import-Normal\">Special Topic: The Cell Cycle and Immortality of Cancer Cells<\/h2>\n<p class=\"import-Normal\">DNA replication is part of a series of preparatory phases that a cell undergoes prior to cell division, collectively known as <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_698\">interphase<\/a> <\/strong>(Figure 4.15). During interphase, the cell not only doubles its chromosomes through DNA replication, but it also increases its metabolic capacity to provide energy for growth and division. Transition into each phase of the cell cycle is tightly controlled by proteins that serve as checkpoints. If a cell fails to pass a checkpoint, then DNA replication and\/or cell division will not continue. Some of the reasons why a cell may fail at a checkpoint is DNA damage, lack of nutrients to continue the process, or insufficient size. In turn, a cell may undergo <strong>apoptosis<\/strong>, which is a mechanism for cell death.<\/p>\n<figure style=\"width: 617px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image11.png\" alt=\"The cell cycle is mostly cell growth and DNA synthesis (interphase), followed by the mitotic phase (mitosis and cytokinesis).\" width=\"617\" height=\"433\" \/><figcaption class=\"wp-caption-text\">Figure 4.15: The phases and checkpoints of the cell cycle. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available.<\/a> Credit: <a href=\"https:\/\/cnx.org\/contents\/jVCgr5SL@15.43:SeU_rWbd@14\/10-2-The-Cell-Cycle\" target=\"_blank\">Cell cycle (Biology 2e, Figure 10.5)<\/a> by<a href=\"https:\/\/openstax.org\/\" target=\"_blank\"> OpenStax<\/a> is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\" target=\"_blank\"> CC BY 4.0 License<\/a>.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p class=\"import-Normal\">Unchecked cellular growth is a distinguishing hallmark of cancer. In other words, as cancer cells grow and proliferate, they acquire the capacity to avoid death and replicate indefinitely. This uncontrolled and continuous cell division is also known as \u201cimmortality.\u201d As previously mentioned, most cells lose the ability to divide due to shortening of telomeres on the ends of chromosomes over time. One way in which cancer cells retain replicative immortality is that the length of their telomeres is continuously protected. Chemotherapy, often used to treat cancer, targets the cell cycle (especially cell division) to halt the propagation of genetically abnormal cells. Another therapeutic approach that continues to be investigated is targeting telomere activity to stop the division of cancer cells.<\/p>\n<figure style=\"width: 296px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image12-1.png\" alt=\"Microscope image of irregularly shaped cells with bright nuclei.\" width=\"296\" height=\"223\" \/><figcaption class=\"wp-caption-text\">Figure 4.16: A microscopic slide of HeLa cancer cells. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:HeLa-III.jpg\" target=\"_blank\">HeLa-III<\/a> by National Institutes of Health (NIH) is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\" target=\"_blank\">public domain<\/a>.<\/figcaption><\/figure>\n<p>Researchers have exploited the immortality of cancer cells for molecular research. The oldest immortal cell line is HeLa cells (Figure 4.16), which were harvested from Henrietta Lacks, an African American woman diagnosed with cervical cancer in 1955. At that time, extracted cells frequently died during experiments, but surprisingly HeLa cells continued to replicate. Propagation of Lacks\u2019s cell line has significantly contributed to medical research, including contributing to ongoing cancer research and helping to test the polio vaccine in the 1950s. However, Lacks had not given her consent for her tumor biopsy to be used in cell culture research. Moreover, her family was unaware of the extraction and remarkable application of her cells for two decades. The history of HeLa cell origin was first revealed in 1976. The controversy voiced by the Lacks family was included in an extensive account of HeLa cells published in Rebecca Skloot\u2019s 2010 book, <em>The Immortal Life of Henrietta Lacks<\/em>. A film based on the book was also released in 2017 (Wolfe 2017).<\/p>\n<\/div>\n<h2 class=\"import-Normal\"><span style=\"text-align: initial;font-size: 1em\">Protein Synthesis<\/span><\/h2>\n<p class=\"import-Normal\">At the beginning of the chapter, we defined <em>proteins<\/em> as strings of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_702\">amino acids<\/a><\/strong> that fold into complex 3-D shapes. There are 20 standard amino acids that can be strung together in different combinations in humans, and the result is that proteins can perform an impressive amount of different functions. For instance, muscle fibres are proteins that help facilitate movement. A special class of proteins (immunoglobulins) help protect the organism by detecting disease-causing pathogens in the body. Protein hormones, such as insulin, help regulate physiological activity. Blood hemoglobin is a protein that transports oxygen throughout the body. <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_704\">Enzymes<\/a> <\/strong>are also proteins, and they are catalysts for biochemical reactions that occur in the cell (e.g., metabolism). Larger-scale protein structures can be visibly seen as physical features of an organism (e.g., hair and nails).<\/p>\n<h3 class=\"import-Normal\"><strong>Transcription and Translation <\/strong><\/h3>\n<figure style=\"width: 272px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image13.jpg\" alt=\"From DNA, transcription creates pre-mRNA, is processed to mature mRNA, translated to an amino acid chain (protein)\" width=\"272\" height=\"336\" \/><figcaption class=\"wp-caption-text\">Figure 4.17: The major steps of protein synthesis. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available.<\/a> Credit: Protein synthesis original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Mary Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p>Nucleotides in our DNA provide the coding instructions on how to make proteins. Making proteins, also known as <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_706\">protein synthesis<\/a><\/strong>, can be broken down into two main steps referred to as <strong>transcription<\/strong> and <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_710\">translation<\/a><\/strong>. The purpose of transcription, the first step, is to make an <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_712\">ribonucleic acid (RNA)<\/a><\/strong> copy of our genetic code. Although there are many different types of RNA molecules that have a variety of functions within the cell, we will mainly focus on <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_714\">messenger RNA (mRNA)<\/a><\/strong>.\u00a0Transcription concludes with the processing (<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_716\">splicing<\/a><\/strong>) of the mRNA. The second step, translation, uses mRNA as the instructions for chaining together amino acids into a new protein molecule (Figure 4.17).<\/p>\n<figure style=\"width: 340px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image14.jpg\" alt=\"Single stranded RNA is composed of 4 types of nucleobases: cytosine, guanine, adenine, and uracil.\" width=\"340\" height=\"461\" \/><figcaption class=\"wp-caption-text\">Figure 4.18: Structural components that form ribonucleic acid (RNA). <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available.<\/a> Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Difference_DNA_RNA-EN.svg\" target=\"_blank\">Difference DNA RNA-EN<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Sponk\" target=\"_blank\">Sponk<\/a> (translation by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Sponk\" target=\"_blank\">Sponk<\/a>, cropped by Katie Nelson) is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\" target=\"_blank\">CC BY-NC-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Unlike double-stranded DNA, RNA molecules are single-stranded nucleotide sequences (Figure 4.18). Additionally, while DNA contains the nucleotide thymine (T), RNA does not\u2014instead its fourth nucleotide is uracil (U). Uracil is complementary to (or can pair with) adenine (A), while cytosine (C) and guanine (G) continue to be complementary to each other.<\/p>\n<p>For transcription to proceed, a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_718\">gene<\/a><\/strong> must first be turned \u201con\u201d by the cell. A gene is a segment of DNA that codes for RNA, and genes can vary in length from a few hundred to as many as two million base pairs in length. The double-stranded DNA is then separated, and one side of the DNA is used as a coding template that is read by <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_720\">RNA polymerase<\/a>.<\/strong> Next, complementary free-floating RNA nucleotides are linked together (Figure 4.19) to form a single-stranded mRNA. For example, if a DNA template is TACGGATGC, then the newly constructed mRNA sequence will be AUGCCUACG.<\/p>\n<p>Genes contain segments called <strong>introns <\/strong>and <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_724\">exons<\/a><\/strong>. Exons are considered \u201ccoding\u201d while introns are considered \u201cnoncoding\u201d\u2014meaning the information they contain will not be needed to construct proteins. When a gene is first transcribed into pre-mRNA, introns and exons are both included (Figure 4.20). However, once transcription is finished, introns are removed in a process called splicing. During splicing, a protein\/RNA complex attaches itself to the pre-mRNA. Next, introns are removed and the remaining exons are connected, thus creating a shorter mature mRNA that serves as a template for building proteins.<\/p>\n<figure style=\"width: 1846px\" class=\"wp-caption alignnone\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image15.jpg\" alt=\"DNA strands pulled apart making space for RNA polymerase to form mRNA using 1 DNA template strand.\" width=\"1846\" height=\"473\" \/><figcaption class=\"wp-caption-text\">Figure 4.19: RNA polymerase catalyzing DNA transcription. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available.<\/a> Credit: <a href=\"https:\/\/www.genome.gov\/glossary\/index.cfm?id=197\" target=\"_blank\">Transcription (2019)<\/a>\u00a0by<a href=\"https:\/\/www.genome.gov\/\" target=\"_blank\"> NIH National Human Genome Research Institute<\/a> has been modified (cropped and labels changed by Katie Nelson) and is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<\/div>\n<figure id=\"attachment_88-4\" aria-describedby=\"caption-attachment-88-4\" style=\"width: 1900px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-88 size-full\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/4.20.jpg\" alt=\"Pre mRNA contains transcriptions of exons and introns. Mature mRNA only contains spliced exon mRNA.\" width=\"1900\" height=\"700\" \/><figcaption id=\"caption-attachment-88-4\" class=\"wp-caption-text\">Figure 4.20: RNA processing is the modification of RNA, including the removal of introns, called splicing, between transcription and translation. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available.<\/a> Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-9\/\" target=\"_blank\">Protein synthesis (Figure 3.23)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<div class=\"__UNKNOWN__\">\n<p class=\"import-Normal\">As described above, the result of transcription is a single-stranded mRNA copy of a gene<strong>. <\/strong>Translation is the process by which amino acids are chained together to form a new protein. During translation, the mature mRNA is transported outside of the nucleus, where it is bound to a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_726\">ribosome<\/a> <\/strong>(Figure 4.21). The nucleotides in the mRNA are read in triplets, which are called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_728\">codons<\/a><\/strong>. Each mRNA codon corresponds to an amino acid, which is carried to the ribosome by a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_730\">transfer RNA<\/a> <\/strong>(tRNA). Thus, tRNAs is the link between the mRNA molecule and the growing amino acid chain.<\/p>\n<figure style=\"width: 651px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image17.jpg\" alt=\"Ribosome and tRNA read mRNA and help join amino acids to a growing polypeptide chain.\" width=\"651\" height=\"366\" \/><figcaption class=\"wp-caption-text\">Figure 4.21: Translation of mRNA into a polypeptide chain composed of the twenty different types of amino acids. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available.<\/a> Credit: <a href=\"https:\/\/www.genome.gov\/genetics-glossary\/Amino-Acids?id=5\" target=\"_blank\">Amino Acids<\/a> by<a href=\"https:\/\/www.genome.gov\/\" target=\"_blank\"> NIH National Human Genome Research Institute<\/a> is in the<a href=\"https:\/\/www.genome.gov\/about-nhgri\/Policies-Guidance\/Copyright\" target=\"_blank\"> public domain<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Continuing with our mRNA sequence example from above, the mRNA sequence AUG-CCU-ACG codes for three amino acids. Using a codon table (Figure 4.22), AUG is a codon for methionine (Met), CCU is proline (Pro), and ACG is threonine (Thr). Therefore, the protein sequence is Met-Pro-Thr. Methionine is the most common \u201cstart codon\u201d (AUG) for the initiation of protein translation in eukaryotes. As the ribosome moves along the mRNA, the growing amino acid chain exits the ribosome and folds into a protein. When the ribosome reaches a \u201cstop\u201d codon (UAA, UAG, or UGA), the ribosome stops adding any new amino acids, detaches from the mRNA, and the protein is released. Depending upon the amino acid sequence, a linear protein may undergo additional \u201cfolding.\u201d The final three-dimensional protein shape is integral to completing a specific structural or functional task.<\/p>\n<div class=\"textbox shaded\">\n<h2 class=\"import-Normal\">Dig Deeper: Protein Synthesis<\/h2>\n<p class=\"import-Normal\">To see protein synthesis in animation, please check out the\u00a0 <a href=\"https:\/\/www.yourgenome.org\/video\/from-dna-to-protein\/\" target=\"_blank\">From DNA to Protein<\/a> video on YourGenome.org.<\/p>\n<\/div>\n<figure style=\"width: 550px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image18-1.png\" alt=\"A circle labeled with letters for mRNA nucleotides.\" width=\"550\" height=\"541\" \/><figcaption class=\"wp-caption-text\">Figure 4.22: This table can be used to identify which mRNA codons (sequence of three nucleotides) correspond with each of the 20 different amino acids. For each mRNA codon, you work in the 5\u2019 to 3\u2019 direction (inside the circle to outside). For example, if the mRNA codon is CAU, you look at the inner circle for the \u201cC,\u201d the middle circle for \u201cA,\u201d and outside circle for \u201cU,\u201d indicating that the CAU codon corresponds with the amino acid \u201chistidine\u201d (abbreviated \u201cHis\u201d or \u201cH\u201d). The table also indicates that the \u201cstart codon\u201d (AUG) correlates with Methionine, and the three \u201cstop\u201d codons are UAA, UAG, and UGA. <a href=\"https:\/\/docs.google.com\/document\/d\/1AKB8mx6Ih-V-1DJ_zxTbf9Jn4puHRCPEhG1rGOlojNc\/edit?usp=sharing\" target=\"_blank\" rel=\"noopener\">An accessible full text RNA codon to amino acid table is available.<\/a> Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Aminoacids_table.svg\" target=\"_blank\">Aminoacids table<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Mouagip\" target=\"_blank\">Mouagip<\/a> has been designated to the <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/cc0\/\" target=\"_blank\">public domain (CC0)<\/a>.<\/figcaption><\/figure>\n<h2 class=\"import-Normal\">Mendelian Genetics<\/h2>\n<figure style=\"width: 183px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image19.png\" alt=\"Stone statue of a robed monk.\" width=\"183\" height=\"239\" \/><figcaption class=\"wp-caption-text\">Figure 4.23: Statue of Mendel located at the Mendel Museum, located at Masaryk University in Brno, Czech Republic. Credit: \u00a0<a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Mendel%C2%B4s_statue.JPG\" target=\"_blank\">Mendel\u00b4s statue<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Coeli\" target=\"_blank\">Coeli<\/a> has been designated to the <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/cc0\/\" target=\"_blank\">public domain (CC0)<\/a>.<\/figcaption><\/figure>\n<p>Gregor Johann Mendel (1822\u20131884) is often described as the \u201cFather of Genetics.\u201d Mendel was a monk who conducted pea plant breeding experiments in a monastery located in the present-day Czech Republic (Figure 4.23). After several years of experiments, Mendel presented his work to a local scientific community in 1865 and published his findings the following year. Although his meticulous effort was notable, the importance of his work was not recognized for another 35 years. One reason for this delay in recognition is that his findings did not agree with the predominant scientific viewpoints on inheritance at the time. For example, it was believed that parental physical traits \u201cblended\u201d together and offspring inherited an intermediate form of that trait. In contrast, Mendel showed that certain pea plant physical traits (e.g., flower color) were passed down separately to the next generation in a statistically predictable manner. Mendel also observed that some parental traits disappeared in offspring but then reappeared in later generations. He explained this occurrence by introducing the concept of \u201cdominant\u201d and \u201crecessive\u201d traits. Mendel established a few fundamental laws of inheritance, and this section reviews some of these concepts. Moreover, the study of traits and diseases that are controlled by a single gene is commonly referred to as <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_732\">Mendelian genetics<\/a><\/strong>.<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<figure style=\"width: 738px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image20.png\" alt=\"Pea plant variation: round\/wrinkled, yellow\/ green pods, white\/purple flowers, tall\/short stem.\" width=\"738\" height=\"304\" \/><figcaption class=\"wp-caption-text\">Figure 4.24: Various phenotypic characteristics of pea plants resulting from different genotypes. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Mendels_peas.png\" target=\"_blank\">Mendels peas<\/a> by Mariana Ruiz <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:LadyofHats\" target=\"_blank\">LadyofHats<\/a> has been designated to the <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/cc0\/\" target=\"_blank\">public domain (CC0 1.0)<\/a>.<\/figcaption><\/figure>\n<p>The physical appearance of a trait is called an organism\u2019s <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_734\">phenotype<\/a><\/strong>. Figure 4.24 shows pea plant (<em>Pisum sativum<\/em>) phenotypes that were studied by Mendel, and in each of these cases the physical traits are controlled by a single gene. In the case of Mendelian genetics, a phenotype is determined by an organism\u2019s <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_736\">genotype<\/a><\/strong>. A genotype consists of two gene copies, wherein one copy was inherited from each parent. Gene copies are also known as <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_738\">alleles<\/a><\/strong> (Figure 4.25), which means they are found in the same gene location on homologous chromosomes. Alleles have a nonidentical DNA sequence, which means their phenotypic effect can be different. In other words, although alleles code for the same trait, different phenotypes can be produced depending on which two alleles (i.e., genotypes) an organism possesses. For example, Mendel\u2019s pea plants all have flowers, but their flower color can be purple or white. Flower color is therefore dependent upon which two color alleles are present in a genotype.<\/p>\n<figure style=\"width: 771px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image21.jpeg\" alt=\"Four pairs of chromosomes. Each chromosome is labeled with an allele, either capital B or lowercase b.\" width=\"771\" height=\"315\" \/><figcaption class=\"wp-caption-text\">Figure 4.25: Homozygous refers to having the same alleles (e.g. two capital Bs or two lowercase bs). Heterozygous refers to having two different alleles (e.g. one capital B and one lowercase b). Credit: <a href=\"https:\/\/www.genome.gov\/genetics-glossary\/homozygous\" target=\"_blank\">Homozygous<\/a> by<a href=\"https:\/\/www.genome.gov\/\" target=\"_blank\"> NIH National Human Genome Research Institute<\/a> is in the<a href=\"https:\/\/www.genome.gov\/about-nhgri\/Policies-Guidance\/Copyright\" target=\"_blank\"> public domain<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">A Punnett square is a diagram that can help visualize Mendelian inheritance patterns. For instance, when parents of known genotypes mate, a Punnett square can help predict the ratio of Mendelian genotypes and phenotypes that their offspring would possess. When discussing genotype, biologists use upper and lower case letters to denote the different allele copies. Figure 4.26 is a Punnett square that includes two <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_740\">heterozygous<\/a><\/strong> parents for flower color (Bb). A heterozygous genotype means there are two different alleles for the same gene. Therefore, a pea plant that is heterozygous for flower color has one purple allele and one white allele. When an organism is <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_742\">homozygous<\/a><\/strong> for a specific trait, it means their genotype consists of two copies of the same allele. Using the Punnett square example, the two heterozygous pea plant parents can produce offspring with two different homozygous genotypes (BB or bb) or offspring that are heterozygous (Bb).<\/p>\n<figure style=\"width: 220px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image22.png\" alt=\"Pollen and Pistol (each with one capital B and one lower case b allele) merge in different combinations.\" width=\"220\" height=\"220\" \/><figcaption class=\"wp-caption-text\">Figure 4.26: Punnett square depicting the possible genetic combinations of offspring from two heterozygous parents. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available.<\/a> Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Punnett_square_mendel_flowers.svg\" target=\"_blank\">Punnett square mendel flowers<\/a> by Madeleine Price Ball (<a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Madprime\" target=\"_blank\">Madprime<\/a>) is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">A pea plant with purple flowers could be heterozygous (Bb) or homozygous (BB). This is because the purple color allele (B) is <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_744\">dominant<\/a> <\/strong>to the white color allele (b), and therefore it only needs one copy of that allele to phenotypically express purple flowers. Because the white flower allele is <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_746\">recessive<\/a><\/strong>, a pea plant must be homozygous for the recessive allele in order to have a white color phenotype (bb). As seen by the Punnett square example (Figure 4.26), three of four offspring will have purple flowers and the other one will have white flowers.<\/p>\n<p class=\"import-Normal\">The Law of Segregation was introduced by Mendel to explain why we can predict the ratio of genotypes and phenotypes in offspring. As discussed previously, a parent will have two alleles for a certain gene (with each copy on a different homologous chromosome). The Law of Segregation states that the two copies will be segregated from each other and will each be distributed to their own gamete. We now know that the process where that occurs is meiosis.<\/p>\n<p class=\"import-Normal\">Offspring are the products of two gametes combining, which means the offspring inherits one allele from each gamete for most genes. When multiple offspring are produced (like with pea plant breeding), the predicted phenotype ratios are more clearly observed. The pea plants Mendel studied provide a simplistic model to understand single-gene genetics. While many traits anthropologists are interested in have a more complicated inheritance (e.g., are informed by many genes), there are a few known Mendelian traits in humans. Additionally, some human diseases also follow a Mendelian pattern of inheritance (Figure 4.27). Because humans do not have as many offspring as other organisms, we may not recognize Mendelian patterns as easily. However, understanding these principles and being able to calculate the probability that an offspring will have a Mendelian phenotype is still important.<\/p>\n<\/div>\n<div align=\"left\">\n<table class=\"grid aligncenter\" style=\"width: 422px;height: 420px\">\n<caption>Figure 4.27: Examples of human diseases with their gene names that follow a Mendelian pattern of inheritance.<\/caption>\n<thead>\n<tr style=\"height: 30px\">\n<td style=\"width: 432.598px;height: 30px\"><strong>Mendelian disorder<\/strong><\/td>\n<td style=\"width: 89.9414px;height: 30px\"><strong>Gene\u00a0<\/strong><\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr style=\"height: 30px\">\n<td style=\"width: 432.598px;height: 30px\">Alpha Thalassemia<\/td>\n<td style=\"width: 89.9414px;height: 30px\">HBA1<\/td>\n<\/tr>\n<tr style=\"height: 30px\">\n<td style=\"width: 432.598px;height: 30px\">Cystic Fibrosis<\/td>\n<td style=\"width: 89.9414px;height: 30px\">CFTR<\/td>\n<\/tr>\n<tr style=\"height: 30px\">\n<td style=\"width: 432.598px;height: 30px\">Fragile X Syndrome<\/td>\n<td style=\"width: 89.9414px;height: 30px\">FMR1<\/td>\n<\/tr>\n<tr style=\"height: 30px\">\n<td style=\"width: 432.598px;height: 30px\">Glucose-6-Phosphate Dehydrogenase Deficiency<\/td>\n<td style=\"width: 89.9414px;height: 30px\">G6PD<\/td>\n<\/tr>\n<tr style=\"height: 30px\">\n<td style=\"width: 432.598px;height: 30px\">Hemophilia A<\/td>\n<td style=\"width: 89.9414px;height: 30px\">F8<\/td>\n<\/tr>\n<tr style=\"height: 30px\">\n<td style=\"width: 432.598px;height: 30px\">Huntington disease<\/td>\n<td style=\"width: 89.9414px;height: 30px\">HTT<\/td>\n<\/tr>\n<tr style=\"height: 30px\">\n<td style=\"width: 432.598px;height: 30px\">Mitochondrial DNA Depletion Syndrome<\/td>\n<td style=\"width: 89.9414px;height: 30px\">TYMP<\/td>\n<\/tr>\n<tr style=\"height: 30px\">\n<td style=\"width: 432.598px;height: 30px\">Oculocutaneous Albinism: Type 1<\/td>\n<td style=\"width: 89.9414px;height: 30px\">TYR<\/td>\n<\/tr>\n<tr style=\"height: 30px\">\n<td style=\"width: 432.598px;height: 30px\">Polycystic Kidney Disease<\/td>\n<td style=\"width: 89.9414px;height: 30px\">PKHD1<\/td>\n<\/tr>\n<tr style=\"height: 30px\">\n<td style=\"width: 432.598px;height: 30px\">Sickle-cell anemia<\/td>\n<td style=\"width: 89.9414px;height: 30px\">HBB<\/td>\n<\/tr>\n<tr style=\"height: 30px\">\n<td style=\"width: 432.598px;height: 30px\">Spinal Muscular Atrophy: SMN1 Linked<\/td>\n<td style=\"width: 89.9414px;height: 30px\">SMN1<\/td>\n<\/tr>\n<tr style=\"height: 30px\">\n<td style=\"width: 432.598px;height: 30px\">Tay-Sachs Disease<\/td>\n<td style=\"width: 89.9414px;height: 30px\">HEXA<\/td>\n<\/tr>\n<tr style=\"height: 30px\">\n<td style=\"width: 432.598px;height: 30px\">Wilson Disease<\/td>\n<td style=\"width: 89.9414px;height: 30px\">ATP7B<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div class=\"__UNKNOWN__\">\n<h3 class=\"import-Normal\"><strong>Example of Mendelian Inheritance: The ABO Blood Group System<\/strong><\/h3>\n<p class=\"import-Normal\">In 1901, Karl Landsteiner at the University of Vienna published his discovery of ABO blood groups. While conducting blood immunology experiments in which he combined the blood of individuals who possess different blood cell types, he observed an agglutination (clotting) reaction. The presence of agglutination implies there is an incompatible immunological reaction; no agglutination will occur in individuals with the same blood type. This work was clearly important because it resulted in a higher survival rate of patients who received blood transfusions. Blood transfusions from someone with a different type of blood causes agglutinations, and the resulting coagulated blood can not easily pass through blood vessels, resulting in death. Landsteiner received the Nobel Prize (1930) for his discovery and explaination of the ABO blood group system.<\/p>\n<p class=\"import-Normal\">Blood <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_748\">cell surface antigens<\/a><\/strong> are proteins that coat the surface of red blood cells, and<strong> antibodies <\/strong>are specifically \u201cagainst\u201d or \u201canti\u201d to the antigens from other blood types. Thus, antibodies are responsible for causing agglutination between incompatible blood types. Understanding the interaction of antigens and antibodies helps to determine ABO compatibility amongst blood donors and recipients. Individuals that are blood type A have A antigens on the red blood cell surface, and anti-B antibodies, which will bind to B antigens should they come in contact. Alternatively, individuals with blood type B have B antigens and anti-A antibodies. Individuals with blood type AB have both A and B antigens but do not produce antibodies for the ABO system. This does not mean type AB does not have any antibodies present, just that specifically anti-A and anti-B antibodies are not produced. Individuals who are blood type O have nonspecific antigens and produce both anti-A and anti-B antibodies.<\/p>\n<p class=\"import-Normal\">Figure 4.28 shows a table of the ABO allele system, which has a Mendelian pattern of inheritance. Both the A and B alleles function as dominant alleles, so the A allele always codes for the A antigen, and the B allele codes for the B antigen. The O allele differs from A and B, because it codes for a nonfunctional antigen protein, which means there is no antigen present on the cell surface of O blood cells. To have blood type O, two copies of the O allele must be inherited, one from each parent, thus the O allele is considered recessive. Therefore, someone who is a heterozygous AO genotype is phenotypically blood type A, and a genotype of BO is blood type B. The ABO blood system also provides an example of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_752\">codominance<\/a><\/strong>, which is when both alleles are observed in the phenotype. This is true for blood type AB: when an individual inherits both the A and B alleles, then both A and B antigens will be present on the cell surface.<\/p>\n<figure style=\"width: 425px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image24.jpg\" alt=\"A table showing the genotypes that can occur from combinations of A, B, and O alleles.\" width=\"425\" height=\"177\" \/><figcaption class=\"wp-caption-text\">Figure 4.28: The different combinations of ABO blood alleles (A, B, and O) to form ABO blood genotypes. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available<\/a>. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-9\/\" target=\"_blank\">ABO Blood Genotypes (Figure 3.33)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Katie Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Also found on the surface of red blood cells is the rhesus group antigen, known as \u201cRh factor.\u201d In reality, there are several antigens on red blood cells independent from the ABO blood system, however, the Rh factor is the second most important antigen to consider when determining blood donor and recipient compatibility. Rh antigens must also be considered when a pregnant mother and her baby have incompatible Rh factors. In such cases, a doctor can administer necessary treatment steps to prevent pregnancy complications and hemolytic disease, which is when the mother\u2019s antibodies break down the newborn\u2019s red blood cells.<\/p>\n<p class=\"import-Normal\">An individual can possess the Rh antigen (be Rh positive) or lack the Rh antigen (be Rh negative). The Rh factor is controlled by a single gene and is inherited independently of the ABO alleles. Therefore, all blood types can either be positive (O+, A+, B+, AB+) or negative (O-, A-, B-, AB-).<\/p>\n<p class=\"import-Normal\">Individuals with O+ red blood cells can donate blood to A+, B+, AB+, and O+ blood type recipients. Because O- individuals do not have AB or Rh antigens, they are compatible with all blood cell types and are referred to as \u201cuniversal donors.\u201d Individuals that are AB+ are considered to be \u201cuniversal recipients\u201d because they do not possess antibodies against other blood types.<\/p>\n<h3 class=\"import-Normal\"><strong>Mendelian Patterns of Inheritance and Pedigrees<\/strong><\/h3>\n<p class=\"import-Normal\">A <strong>pedigree<\/strong> can be used to investigate a family\u2019s medical history by determining if a health issue is inheritable and will possibly require medical intervention. A pedigree can also help determine if it is a Mendelian recessive or dominant genetic condition. Figure 4.29 is a pedigree example of a family with Huntington\u2019s disease, which has a Mendelian dominant pattern of inheritance. In a standard pedigree, males are represented by a square and females are represented by a circle. Biological family members are connected to a horizontal line, with biological parents above and offspring below. When an individual is affected with a certain condition, the square or circle is filled in as a solid color. With a dominant condition, at least one of the parents will have the disease and an offspring will have a 50% chance of inheriting the affected chromosome. Therefore, dominant genetic conditions tend to be present in every generation. In the case of Huntington\u2019s, some individuals may not be diagnosed until later in adulthood, so parents may unknowingly pass this dominantly inherited disease to their children.<\/p>\n<figure style=\"width: 389px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image25.png\" alt=\"A three-generation pedigree with about half the individuals shaded in. Please see text discussion for details.\" width=\"389\" height=\"189\" \/><figcaption class=\"wp-caption-text\">Figure 4.29: A pedigree depicting an example of dominant Mendelian inheritance like Huntington\u2019s. Offspring with the trait will have at least one parent with the same trait. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-9\/\" target=\"_blank\">Mendelian dominant pattern of inheritance (Figure 3.34)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Beth Shook is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Because the probability of inheriting a disease-causing recessive allele is more rare, recessive medical conditions can skip generations. Figure 4.30 is an example of a family that carries a recessive cystic fibrosis mutation. A parent that is heterozygous for the cystic fibrosis allele has a 50% chance of passing down their affected chromosome to the next generation. If a child has a recessive disease, then it means both of their parents are <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_756\">carriers<\/a><\/strong> (heterozygous) for that condition. In most cases, carriers for recessive conditions show no serious medical symptoms. Individuals whose family have a known medical history for certain conditions sometimes seek family planning services (see the Genetic Testing section).<\/p>\n<\/div>\n<div><\/div>\n<div class=\"__UNKNOWN__\">\n<figure style=\"width: 392px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image26.png\" alt=\"A three-generation pedigree with three individuals with the trait shaded in. Please see text discussion for details.\" width=\"392\" height=\"215\" \/><figcaption class=\"wp-caption-text\">Figure 4.30: A pedigree depicting an example of recessive Mendelian inheritance like cystic fibrosis. Individuals may have a trait not observed in the previous generation. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-9\/\" target=\"_blank\">Mendelian recessive pattern of inheritance (Figure 3.35)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Beth Shook is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Pedigrees can also help distinguish if a health issue has either an <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_758\">autosomal<\/a> <\/strong>or <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_760\">X-linked<\/a><\/strong> pattern of inheritance. As previously discussed, there are 23 pairs of chromosomes and 22 of these pairs are known as autosomes. The provided pedigree examples (Figure 4.29-30) are autosomally linked genetic diseases. This means the genes that cause the disease are on one of the chromosomes numbered 1 to 22. The conditions caused by genes located on the X chromosome are referred to as X-linked diseases.<\/p>\n<p class=\"import-Normal\">Figure 4.31 depicts a family in which the mother is a carrier for the X-linked recessive disease Duchenne Muscular Dystrophy (DMD). The mother is a carrier for DMD, so daughters and sons will have a 50% chance of inheriting the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_762\">pathogenic<\/a><\/strong> <em>DMD<\/em> allele. Because females have two X chromosomes, females who inherit only one copy will not have the disease (although in rare cases, female carriers may show some symptoms of the disease). On the other hand, males who inherit a copy of an X-linked pathogenic <em>DMD<\/em> allele will typically be affected with the condition. Thus, males are more susceptible to X-linked conditions because they only have one X chromosome. Therefore, when evaluating a pedigree, if a higher proportion of males are affected with the disease, this could suggest the disease is X-linked recessive. <br style=\"clear: both\" \/><br style=\"clear: both\" \/>Compared to the X chromosome, the Y chromosome is smaller with only a few genes. Y-linked traits are therefore rare and can only be passed from a chromosomal father to a biological XY child.<\/p>\n<figure style=\"width: 407px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image27.jpg\" alt=\"A three-generation pedigree with four males and one female with the trait. Please see text discussion for details.\" width=\"407\" height=\"236\" \/><figcaption class=\"wp-caption-text\">Figure 4.31: A pedigree depicting an example of X-linked Mendelian inheritance like Duchenne Muscular Dystrophy (DMD). Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-9\/\" target=\"_blank\">X-linked recessive pattern of inheritance (Figure 3.36)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Beth Shook is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<h2 class=\"import-Normal\">Other Patterns of Inheritance<\/h2>\n<h3 class=\"import-Normal\"><strong>Complexity Surrounding Mendelian Inheritance<\/strong><\/h3>\n<p class=\"import-Normal\">Pea plant trait genetics are relatively simple compared to what we know about genetic inheritance today. The vast majority of genetically controlled traits are not strictly dominant or recessive, so the relationship among alleles and predicting phenotype is often more complicated. For example, traits that exhibit<strong> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_764\">incomplete dominance<\/a><\/strong> occur when a heterozygote exhibits a phenotype that is an intermediate phenotype of both alleles. In snapdragon flowers, the red flower color (R) is dominant and white is recessive (r). Therefore, the homozygous dominant RR is red and homozygous recessive rr is white. However, because the R allele is not completely dominant, the heterozygote Rr is a blend of red and white, which results in a pink flower (Figure 4.32).<\/p>\n<figure style=\"width: 302px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image28.png\" alt=\"Snapdragon flowers in many hues.\" width=\"302\" height=\"188\" \/><figcaption class=\"wp-caption-text\">Figure 4.32: Snap dragons with different genotypes resulting in different flower color phenotypes. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Antirrhinum_aka_Snap_dragon_at_lalbagh_7112.JPG\" target=\"_blank\">Antirrhinum a.k.a. Snap dragon at lalbagh 7112<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Rameshng\" target=\"_blank\">Rameshng<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">An example of incomplete dominance in humans is the enzyme \u03b2-hexosaminidase A (Hex A), which is encoded by the gene <em>HEXA<\/em>. Patients with two dysfunctional <em>HEXA <\/em>alleles are unable to metabolize a specific lipid-sugar molecule (GM2 ganglioside); because of this, the molecule builds up and causes damage to nerve cells in the brain and spinal cord. This condition is known as Tay-Sachs disease, and it usually appears in infants who are three to six months old. Most children with Tay-Sachs do not live past early childhood. Individuals who are heterozygous for the functional type <em>HEXA<\/em> allele and one dysfunctional allele have reduced Hex A activity. However, the amount of enzyme activity is still sufficient, so carriers do not exhibit any neurological phenotypes and appear healthy.<\/p>\n<p class=\"import-Normal\">Some genes and alleles can also have higher <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_766\">penetrance<\/a><\/strong> than others. Penetrance can be defined as the proportion of individuals who have a certain allele and also express an expected phenotype. If a genotype always produces an expected phenotype, then those alleles are said to be fully penetrant. However, in the case of incomplete (or reduced) penetrance, an expected phenotype may not occur even if an individual possesses the alleles that are known to control a trait or cause a disease.<\/p>\n<p class=\"import-Normal\">A well-studied example of genetic penetrance is the cancer-related genes <em>BRCA1<\/em> and <em>BRCA2<\/em>. Mutations in these genes can affect crucial processes such as DNA repair, which can lead to breast and ovarian cancers. Although <em>BRCA1<\/em> and <em>BRCA2<\/em> mutations have an autosomal dominant pattern of inheritance, it does not mean an individual will develop cancer if they inherit a pathogenic allele. Several lifestyle and environmental factors can also influence the risk for developing cancer. Regardless, if a family has a history of certain types of cancers, then it is often recommended that genetic testing be performed for individuals who are at risk. Moreover, publically available genetic testing companies are now offering health reports that include <em>BRCA1<\/em> and <em>BRCA2<\/em> allele testing (see the Genetic Testing section).<\/p>\n<h3 class=\"import-Normal\"><strong>Polygenic Traits<\/strong><\/h3>\n<p class=\"import-Normal\">While Mendelian traits tend to be influenced by a single gene, the vast majority of human phenotypes are <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_768\">polygenic traits<\/a><\/strong>. The term <em>polygenic<\/em> means \u201cmany genes.\u201d Therefore, a polygenic trait is influenced by many genes that work together to produce the phenotype. Human phenotypes such as hair color, eye color, height, and weight are examples of polygenic traits. Hair color, for example, is largely determined by the type and quantity of a pigment called melanin, which is produced by a specialized cell type within the skin called melanocytes. The quantity and ratio of melanin pigments determine black, brown, blond, and red hair colors. <em>MC1R<\/em> is a well-studied gene that encodes a protein expressed on the surface of melanocytes that is involved in the production of eumelanin pigment. Typically, people with two functional copies of <em>MC1R <\/em>have brown hair. People with reduced functioning <em>MC1R<\/em> allele copies tend to produce pheomelanin, which results in blond or red hair. However, <em>MC1R <\/em>alleles have variable penetrance, and studies are continually identifying new genes (e.g., <em>TYR<\/em>, <em>TYRP1<\/em>, <em>SLC24A5<\/em>, and <em>KITLG<\/em>) that also influence hair color. Individuals with two nonfunctioning copies of the gene <em>TYR<\/em> have a condition called oculocutaneous albinism\u2014their melanocytes are unable to produce melanin so these individuals have white hair, light eyes, and pale skin.<\/p>\n<p class=\"import-Normal\">In comparison to Mendelian diseases, <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_770\">complex diseases<\/a><\/strong> (e.g., Type II diabetes, coronary heart disease, Alzheimer's, and schizophrenia) are more prevalent in humans. Complex diseases are polygenic, but their development is also influenced by physical, environmental, sociocultural, and individual lifestyle factors. Families can be more predisposed to certain diseases; however, complex diseases often do not have a clear pattern of inheritance.<\/p>\n<p class=\"import-Normal\">Although research of complex traits and diseases continue, geneticists may not know all of the genes involved with a given complex disease. Additionally, how much genetic versus nongenetic determinants contribute to a disease phenotype can be difficult to decipher. Therefore, predicting individual medical risk and risk across different human populations is often a significant challenge. For instance, cardiovascular diseases (CVDs) continue to be one of the leading causes of death around the world. Development of CVDs has been linked to nutrient exposure during fetal development, high fat and sedentary lifestyles, drug usage, adverse socioeconomic conditions, and various genes. Human environments are diverse, and public health research including the field of Human Biology can help identify risk factors and behaviors associated with chronic diseases. Large-scale clinical genetic studies with powerful bioinformatic approaches can also help elucidate some of these complex relationships.<\/p>\n<h2 class=\"import-Normal\">Genomics and Epigenetics<\/h2>\n<p class=\"import-Normal\">A <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_772\">genome<\/a><\/strong> is all of the genetic material of an organism. In the case of humans, this includes 46 chromosomes and mtDNA. The human genome contains approximately three billion base pairs of DNA and has regions that are both noncoding and coding. Scientists now estimate that the human genome contains 20,000\u201325,000 protein-coding genes, with each chromosome containing a few hundred to a few thousand genes. As our knowledge of heredity increases, researchers have begun to realize the importance of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_774\">epigenetics<\/a><\/strong>, or changes in gene expression that do not result in a change of the underlying DNA sequence. Epigenetics research is also crucial for unraveling gene regulation, which involves complex interactions between DNA, RNA, proteins, and the environment.<\/p>\n<h3 class=\"import-Normal\"><strong>Genomics<\/strong><\/h3>\n<p class=\"import-Normal\">The vast majority of the human genome is noncoding, meaning there are no instructions to make a protein or RNA product in these regions. Historically, noncoding DNA was referred to as \u201cjunk DNA\u201d because these vast segments of the genome were thought to be irrelevant and nonfunctional. However, continual improvement of DNA <strong>sequencing<\/strong> technology along with worldwide scientific collaborations and consortia have contributed to our increased understanding of how the genome functions. Through these technological advances and collaborations, we have since discovered that many of these noncoding DNA regions are involved in dynamic genetic regulatory processes.<\/p>\n<p class=\"import-Normal\">Genomics is a diverse field of molecular biology that focuses on genomic evolution, structure, and function; gene mapping; and <strong>genotyping <\/strong>(determining the alleles present). Evolutionary genomics determined that humans share about 98.8% percent of their DNA with chimpanzees. Given the phenotypic differences between humans and chimpanzees, having a DNA sequence difference of 1.2% seems surprising. However, a lot of genomics research is also focused on understanding how noncoding genomic regions influence how individual genes are turned \u201con\u201d and \u201coff\u201d (i.e., regulated). Therefore, although DNA sequences are identical, regulatory differences in noncoding genetic regions (e.g., promoters) are believed to be largely responsible for the physical differences between humans and chimpanzees.<\/p>\n<p class=\"import-Normal\">Further understanding of genomic regulatory elements can lead to new therapies and personalized treatments for a broad range of diseases. For example, targeting the regulatory region of a pathogenic gene to \u201cturn off\u201d its expression can prevent its otherwise harmful effects. Such molecular targeting approaches can be personalized based on an individual\u2019s genetic makeup. Genome-wide association studies (GWAS), which seek to determine genes that are linked to complex traits and diseases, typically require significant computational efforts. This is because millions of DNA sequences must be analysed and GWAS sometimes include thousands of participants. During the beginning of the genomics field, most of the large-scale genomics studies only included North American, European, and East Asian participants and patients. Researchers are now focusing on increasing ethnic diversity in genomic studies and databases. In turn, accuracy of individual disease risk across all human populations will be improved and more rare disease\u2013causing alleles will be identified.<\/p>\n<h3 class=\"import-Normal\"><strong>Epigenetics<\/strong><\/h3>\n<p class=\"import-Normal\">All cells within your body have the same copy of DNA. For example, a brain neuron has the same DNA blueprint as does a skin cell on your arm. Although these cells have the same genetic information, they are considered specialized. The reason all cells within the body have the same DNA but different morphologies and functions is that different subsets of genes are turned \u201con\u201d and \u201coff\u201d within the different cell types. A more precise explanation is that there is differential expression of genes among different cell types. In the case of neuronal cells, a unique subset of genes are active that allow them to grow axons to send and receive messages. This subset of genes will be inactive in non-neuronal cell types such as skin cells. Epigenetics is a branch of genetics that studies how these genes are regulated through mechanisms that do not change the underlying DNA sequence.<\/p>\n<p class=\"import-Normal\">The prefix <em>epi-<\/em> means \u201con, above, or near,\u201d and epigenetic mechanisms such as <strong>DNA methylation<\/strong> and histone modifications occur on, above, or near DNA. The addition of a methyl group (\u2014 CH\u2083) to DNA is known as DNA methylation (Figure 4.33). DNA methylation and other modifications made to the histones around which DNA are wrapped are thought to make chromatin more compact. This DNA is inaccessible to transcription factors and RNA polymerases, thus preventing genes from being turned on (i.e., transcribed). Other histone modifications have the opposite effect by loosening chromatin, which makes genes accessible to transcription factors.<\/p>\n<figure style=\"width: 510px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image29.png\" alt=\"Epigenetic histone tail modifications that can tighten and loosen the chromatin of DNA. \" width=\"510\" height=\"395\" \/><figcaption class=\"wp-caption-text\">Figure 4.33: Different types of epigenetic histone tail modifications that can tighten (top) and loosen (bottom) the chromatin of DNA. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available.<\/a> Credit: <a href=\"https:\/\/cnx.org\/contents\/jVCgr5SL@15.43:5cz8bfb2@10\/16-3-Eukaryotic-Epigenetic-Gene-Regulation\" target=\"_blank\">Epigenetic Control (Biology 2e, Figure 16.7)<\/a> by<a href=\"https:\/\/openstax.org\/\" target=\"_blank\"> OpenStax<\/a> is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\" target=\"_blank\"> CC BY 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">It is important to note that environmental factors can alter DNA methylation and histone modifications and also that these changes can be passed from generation to generation. For example, someone\u2019s <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_782\">epigenetic profile<\/a><\/strong> can be altered during a stressful time (e.g., natural disasters, famine, etc.), and those regulatory changes can be inherited by the next generation. Moreover, our epigenetic expression profile changes as we age. For example, certain places in our genome become \u201chyper\u201d or \u201chypo\u201d methylated over time. Identical twins also have epigenetic profiles that become more different as they age. Researchers are only beginning to understand the significance of these genome-wide epigenetic changes. Scientists have also discovered that changes in epigenetic modifications can alter gene expression in ways that contribute to diseases. It is also important to note that, unlike DNA mutations (which permanently change the nucleotide sequence), epigenetic changes can be easily reversed. A lot of research now focuses on how drugs can alter or modulate changes in DNA methylation and histone modifications to treat diseases such as cancer.<\/p>\n<div class=\"textbox shaded no-borders\" style=\"background: var(--lightblue)\">\n<h2>Environmental Disruptors and Their Impact on Human Reproductive Systems<\/h2>\n<p>The National Institute of Environmental Health Sciences (NIEHS) defines endocrine-disrupting chemicals (EDCs) as synthetic or natural compounds that interfere with the body\u2019s hormonal systems. Found in pesticides, plastics, industrial chemicals, and pollutants, EDCs can mimic, block, or alter the natural action of hormones (NIEHS, 2024). Their effects on reproductive health are profound, particularly during critical developmental windows while also affecting subsequent generations through epigenetic changes.<\/p>\n<p>NIEHS declared EDC\u2019s:<\/p>\n<div align=\"center\">\n<table>\n<tbody>\n<tr>\n<td>Atrazine<\/td>\n<td>one of the most commonly applied herbicides in the world, often used to control weeds in corn, sorghum, and sugarcane crops.<\/td>\n<\/tr>\n<tr>\n<td>Bisphenol A (BPA)<\/td>\n<td>used to make polycarbonate plastics and epoxy resins. It is used in manufacturing, food packaging, toys, and other applications. BPA resins may be found in the lining of some canned foods and beverages.<\/td>\n<\/tr>\n<tr>\n<td>Dioxins<\/td>\n<td>a byproduct of certain manufacturing processes, such as herbicide production and paper bleaching. They can be released into the air from waste burning and wildfires.<\/td>\n<\/tr>\n<tr>\n<td>Perchlorate<\/td>\n<td>a colorless salt manufactured and used as an industrial chemical to make rockets, explosives, and fireworks, which can be found in some groundwater.<\/td>\n<\/tr>\n<tr>\n<td>Polyfluoroalkyl Substances (PFAS)<\/td>\n<td>a large group of chemicals used widely in industrial applications, such as firefighting foam, nonstick pans, paper, and textile coatings.<\/td>\n<\/tr>\n<tr>\n<td>Phthalates<\/td>\n<td>a large group of compounds used as liquid plasticizers. They are found in hundreds of products including some food packaging, cosmetics, fragrances, children\u2019s toys, and medical device tubing. Cosmetics that may contain phthalates include nail polish, hair spray, aftershave lotion, cleanser, and shampoo.<\/td>\n<\/tr>\n<tr>\n<td>Phytoestorgens<\/td>\n<td>naturally occurring substances with hormone-like activity found in some plants; they may have a similar effect to estrogen produced by the body. Soy foods, for example, contain phytoestrogens.<\/td>\n<\/tr>\n<tr>\n<td>Polybrominated diphenyl ethers (PBDE)<\/td>\n<td>used to make flame retardants for products such as furniture foam and carpet.<\/td>\n<\/tr>\n<tr>\n<td>Polychlorinated biphenyls (PCBs)<\/td>\n<td>used to make electrical equipment, such as transformers, and are in hydraulic fluids, heat transfer fluids, lubricants, and plasticizers. PCBs were mass-produced globally until they were banned in 1979.<\/td>\n<\/tr>\n<tr>\n<td>Triclosan<\/td>\n<td>an ingredient that was previously added to some antimicrobial and personal care products, like liquid body wash and soaps.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h3 style=\"text-align: left\">The Male Reproductive System: Vulnerabilities, Epigenetics, and Disruptions<\/h3>\n<p style=\"text-align: left\">The male reproductive system is highly sensitive to hormonal interference, especially during prenatal and early postnatal development. Over the past 50 years, epidemiological data gathered by the NIEHS has revealed alarming changes: increased cases of prostate and testicular cancers, male-descended testes, and anatomical malformations of male genitalia (Sweeney Et al., 2015). These changes are accompanied by a global decline in sperm quality, underscoring the widespread vulnerability of male reproductive health to environmental factors. The testes, as the site of sperm production and testosterone synthesis, are particularly susceptible to EDC interference. Proper testicular development depends on tightly regulated hormonal signalling, which EDCs can disrupt by mimicking or blocking hormones like testosterone and estrogen, leading to improper testicular formation and increased risk of testicular cancer. Prostate development is also a target for EDC interference. African American men, for example, exhibit twice the risk of developing prostate cancer than Caucasian men. This disparity has been attributed to hereditary, lifestyle, and environmental factors, often causing elevated maternal estrogen levels during gestation. This prenatal exposure to EDCs can mimic estrogen and predispose developing prostate tissues to cancerous changes in adulthood (2015).<\/p>\n<h3 style=\"text-align: left\">The Female Reproductive System: Epigenetics and Fertility Challenges<\/h3>\n<p style=\"text-align: left\">Female fertility relies on a delicate hormonal balance to regulate processes such as ovulation, implantation, and pregnancy. EDCs can disrupt this balance by mimicking, antagonizing, or altering the action of hormones. Their interference contributes to a wide range of reproductive disorders, including early puberty, premature ovarian failure, anovulation, and infertility. Epigenetics plays a central role in female reproductive health. DNA methylation, histone modifications, and ncRNA generation are crucial for regulating ovarian and uterine function; However, EDCs can affect these regulatory mechanisms. An example of this is primordial germ cells (PGCs) in female embryos, which need to undergo extensive epigenetic reprogramming during development (Biswas Et al., 2021). This process erases genomic imprinting and reactivates the inactive X chromosome, creating a \"blank slate\" for the next generation; however, EDCs can disrupt this critical period of epigenetic resetting, leading to long-term consequences for reproductive health.<\/p>\n<p style=\"text-align: left\">The ovarian follicle\u2013the functional unit of female reproduction\u2013is particularly vulnerable to these chemicals. Being exposed to EDCs can deplete the pool of these follicles, leading to temporary or permanent infertility (2021). Additionally, EDCs interfere with estrogen receptor function, a crucial regulator of female reproductive processes. These chemicals bind to these receptors, altering the recruitment of enzymes involved in histone modification and chromatin remodelling; this disrupts gene expression patterns critical for ovarian and uterine health. One striking example is diethylstilbestrol (DES), a synthetic estrogen once prescribed to pregnant women (2021). DES exposure has been linked to ovarian cancer in subsequent generations, highlighting the transgenerational effects of EDCs on the female reproductive system. In severe cases, EDCs induce multigenerational reproductive disorders, as observed in studies linking DES to ovarian cancer in the grandchildren of exposed individuals.<\/p>\n<\/div>\n<\/div>\n<h2 style=\"text-align: left\">Epigenetic Therapy<\/h2>\n<h3 style=\"text-align: left\">Heritable Changes and Some Related Drugs<\/h3>\n<p style=\"text-align: left\">As has been said, epigenetics involves heritable changes in gene expression, without involving DNA alteration. These changes, being heritable and often involving abnormal DNA methylation patterns within the four DNA methyltransferases (DNMTs) or histone modifications in chromatin, can lead to disease development. DNMTs (DNMT1, DNMT2, DNMT3A, and DNMT3B) have functions specific to themselves and are at the core of the DNA methylation process. Regarding the histone modifications mentioned, histones have been recognized to mutate under various mechanisms, such as acetylation, methylation and phosphorylation. The acetylation of histones involves histone acetyltransferases (HATs), which are associated with the activation of gene transcription. This process is reversed by the deacetylation of histones, which is associated with the silencing of gene transcription under histone deacetylases (HDACs). (Peedicayil, 2006)<\/p>\n<p style=\"text-align: left\">Epigenetic therapy, with the use of specialized drug developments, aims to correct epigenetic defects, which are reversible under pharmacological intervention, by targeting enzymes such as HATs, HDACs and DNMTs, as well as histone methyltransferases. For instance, certain drugs are being developed as DNMT inhibitors, stopping the methylation of DNA associated with inappropriate transcriptional silencing of genes, and potentially increasing haemoglobin F to help patients affected by sickle cell anemia. These DNMT inhibitor drugs have been classified under three categories based on their structures: nucleoside analogue DNMT inhibitors, non-nucleoside analogue DNMT inhibitors, and antisense oligonucleotides (2006). Nucleoside analogue DNMT inhibitors are analogues of cytosine, the nucleotide affected by methylation from DNMTs, and are incorporated into replicating DNA, replacing cytosine, thus being S-phase-specific drugs. Non-nucleoside analogue DNMT inhibitors are researched to reduce the myelotoxic effects of drugs directly incorporated into the DNA, and are brought into the patient differently. Antisense oligonucleotides are drugs made up of sequences of nucleotides complementary to mRNAs, made to block translation, by acting on the DNMT1 for instance. Additionally, drugs such as HDAC inhibitors help maintain the acetylation of histones, leading to apoptosis, growth arrest or differentiation of tumour cells, giving this drug an anticancer effect, suppressing tumour growth. (2006)<\/p>\n<h3 style=\"text-align: left\">Implications with Cancers<\/h3>\n<p style=\"text-align: left\">Research published in\u00a0<em>The Indian Journal for Medical Research<\/em> has shown that these drugs show promising results in cancer treatment trials involving solid tumours and hematological malignancies. However, they have limitations, for instance, the fact that DNMT and HDAC inhibitors could activate oncogenes due to limited specificity, leading to further tumor progression; or their high myelotoxicity levels, a side effect thought to be due to their incorporation into DNA, and nucleotide analogue inhibitors (2006). Though that is the case, it is important to know that epigenetic drugs alone or in combination with conventional anticancer drugs, may prove to be a significant advance over the use of conventional anticancer drugs, and may also be a way to prevent diseases. Additionally, combination therapy strategies targeting various epigenetic markers, such as DNMTs for cancer-related genes and non-selective HDAC inhibitors, have been shown to yield promising results, simultaneously inducing the expression of tumor suppressor genes and inhibiting the expression of key oncogenes.\u00a0<span style=\"margin: 0px;padding: 0px\">As recently explored by researchers in\u00a0<em>Cell Death Discovery<\/em>, this specific case of combination therapy would synergistically induce gene expression while maintaining the selectivity required to increase targeting of particular tumor types based on gene expression profiles.<\/span> (Yu Et al., 2024)<\/p>\n<p style=\"text-align: left\">To date, the majority of cases in which epigenetic defects have led to disease pathogenesis are cancers (Peedicayil, 2006), cancer cells often developing due to uncontrolled cell growth and resistance to cell death mechanisms, made possible with abnormal DNA methylation patterns as well as histone modifications (Yu Et al., 2024). Epigenetic alterations have therefore been identified within the core of tumor progression mechanisms in cancer cells, including tumorigenesis, promotion, progression, and recurrence, suggesting epigenetic heterogeneity at the cellular level (2024). Certain drugs have been developed, showing specifically good results for cancer treatments, by inhibiting enzymes such as KMTs and KDMs. These can be added to the growing list of drugs fitting into epigenetic therapy, including DNMT and HDAC inhibitors, as well as combination therapy treatments, for cancer and other diseases.<\/p>\n<h3 style=\"text-align: left\">Purpose of Study and Future Developments<\/h3>\n<p style=\"text-align: left\">Studying the link between epigenetics and diseases is crucial for multiple reasons, one of which is enabling scientists and researchers to better understand disease mechanisms, detect abnormal epigenetic changes, and, in turn, develop more effective treatments or possibly even prevent diseases from developing in the first place. As previously mentioned, epigenetic therapy has been shown to bring promising results in drug trials surrounding cancer treatments. Still, the range of diseases to be treated with this new pharmacology approach is vast, molecules other than DNMTs and HDACs being related to epigenetic mechanisms within gene expression, such as BET proteins and KDMs, potentially being a source of new medications or treatments (Yu Et al., 2024; Peedicayil, 2006). Additionally, by understanding someone's epigenetic profile, a form of personalized \u201cprecision medicine\u201d (2024, p. 8) is developed, offering less toxic and more effective treatments with fewer undesired side effects. Researchers expanding this field of knowledge would be able to understand, in more concrete terms, how external factors are linked to epigenetic changes and, consequently, disease risk, potentially halting disease progression and developing new prevention mechanisms. Personalized medicine combines both genetic and epigenetic data, including gene expression profiles, DNA methylation patterns, histone modification profiles, and identified biomarkers, to create precise disease management and prediction.<\/p>\n<p style=\"text-align: left\">It is crucial to keep in mind that diseases like cancer are linked to major causes of morbidity and mortality worldwide, which could be reduced with therapeutic medicine such as epigenetic therapy, aiming to detect cancer biomarkers to improve risk assessment, diagnosis, and targeted treatment interventions, limiting the burden of chronic and life-threatening diseases. With the advancement of epigenetic therapies, new sequencing techniques, as well as AI (2024), have opened avenues to establish precision diagnostics and therapeutics for patients.<\/p>\n<p style=\"text-align: left\">With this said, epigenetics is a relatively new area of scientific research. This field has exploded in the last few decades, especially with the advancement of technologies that allow researchers to examine DNA methylation patterns, histone modifications, and non-coding RNA molecules across the genome. While the potential of epigenetics in explaining complex diseases, including those linked to environmental factors such as endocrine-disrupting chemicals (EDCs), is immense, we\u2019ve identified two key challenges. One major limitation is the complexity and variability of epigenetic marks. These modifications can differ significantly across cell types, tissues, and even individuals, making it difficult to generalize findings.<\/p>\n<p style=\"text-align: left\">Additionally, epigenetic changes are dynamic and can fluctuate over time, which complicates the task of linking them to specific environmental exposures or health outcomes. Another challenge lies in the transgenerational aspect of epigenetics. While it's clear that epigenetic changes can be passed from one generation to the next, the mechanisms behind this inheritance are not fully understood. It's also difficult to pinpoint exactly when and how these modifications occur in development, especially since environmental exposures may affect individuals at different stages of their life, with varying effects depending on the timing and dose.<\/p>\n<div class=\"textbox\">\n<h2>Special Topic: Epigenetics and X Chromosome Inactivation<\/h2>\n<figure style=\"width: 181px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image30.jpg\" alt=\"A cat that has a multicolored coat pattern in colors of black, orange, and white.\" width=\"181\" height=\"201\" \/><figcaption class=\"wp-caption-text\">Figure 4.34: A multicolored coat pattern as the result of X chromosome inactivation during development. Credit: \u201cRue\u201d the calico cat by Hayley Mann is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\"> CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p>Mary Lyon was a British geneticist who presented a hypothesis for X chromosome inactivation (called the <em>Lyon hypothesis<\/em>) based on her work and other studies of the day. Females inherit two X chromosomes, one from each parent. Males have one functional X chromosome; however, this does not mean females have more active genes than males. During the genetic embryonic development of many female mammals, one of the X chromosomes is inactivated at random, so females have one functional X chromosome. The process of X chromosome inactivation in females occurs through epigenetic mechanisms, such as DNA methylation and histone modifications. Recent studies have analysed the role of a long noncoding RNA called X-inactive specific transcript (XIST), which is largely responsible for the random silencing of one of the X chromosomes. The presence of two X chromosomes is the signal for XIST RNA to be expressed so that one X chromosome can be inactivated. However, some cells may have an active paternal X chromosome while other cells may have an active maternal X chromosome. This phenomenon is easily seen in calico and tortoiseshell cats (Figure 4.34). In cats, the gene that controls coat color is found on the X chromosome. During early embryo development, random inactivation of X chromosomes gives rise to populations of cells that express black or orange, which results in the unique coat patterning. Therefore, calico cats are typically always female.<\/p>\n<\/div>\n<h2 class=\"import-Normal\">Genetic Testing<\/h2>\n<p class=\"import-Normal\">To assist with public health efforts, newborn screening for genetic diseases has been available in the United States for over 50 years. One of the first available genetic tests was to confirm a phenylketonuria (PKU) diagnosis in infants, which is easily treatable with a dietary change. Currently, each state decides what genes are included on newborn screening panels and some states even have programs to help with infant medical follow-ups. There are now hundreds of laboratories that provide testing for a few thousand different genes that can inform medical decisions for infants and adults. Moreover, genetic testing has been made available publicly to anyone without the assistance of medical professionals.<\/p>\n<h3 class=\"import-Normal\"><strong>Clinical Testing<\/strong><\/h3>\n<p class=\"import-Normal\">Clinical genetics tests assist patients with making medically informed decisions about family planning and health. Applications of this technology include assistance with<em> in vitro<\/em> fertilization (IVF) procedures, embryo genetic screening, and personalized medicine such as matching patients to cancer therapies. To ensure accuracy of patient genetic screening, it is important that all clinical laboratories are regulated. The Clinical Laboratory Improvement Amendments (CLIA) are United States federal standards that all human laboratory testing clinics must follow. A major benefit provided by some clinical genetic testing companies is access to genetic counselors, who have specialized education and training in medical genetics and counseling. For individuals with a family history of genetic disease, a physician may recommend genetic carrier screening to see if there is a risk for passing on a disease to a child. Genetic counselors provide expertise with interpretation of genetic testing results, as well as help guide and support patients when making impactful medical decisions.<\/p>\n<h2>Cultural Connections and Contemporary Implications<\/h2>\n<p>From the late nineteenth century to the present, humanity\u2019s desire to direct its own biological destiny has raised profound questions for biological anthropologists. The study of human evolution is not only a scientific exploration of change over time\u2014it is also a reflection of how societies interpret difference, fitness, and social value. The history of eugenics, and its modern echoes in genomic technology, reveal how evolutionary theory can be misused to justify inequality, as well as how culture continues to shape the biological future of our species.<\/p>\n<p>The roots of eugenics lie in Social Darwinism, where figures such as Francis Galton (a cousin of Darwin) believed that basic natural selection was insufficient, opting for more involved methods of social engineering through selective breeding. This perspective assumed that complex human traits such as intelligence, morality, or poverty could be biologically inherited and thus controlled. In this view, biological determinism replaced social responsibility, and \u201cfitness\u201d became a political and cultural judgment rather than a biological one.<\/p>\n<p>Throughout the early twentieth century, eugenic policies spread across the globe, shaping laws and public health initiatives. In Canada, government-backed programs continuing into the 1970s, enforced the sterilization of Indigenous women, coercing them with threats of withdrawing future healthcare. Germany famously drew upon such precedents in developing its racial hygiene programs during the Second World War, transforming eugenic ideology into a state-sponsored campaign of genocide. Even by the late twentieth century, echoes of eugenics persisted in Peru, where population control initiatives targeted Indigenous communities for compulsory sterilization.<\/p>\n<p>In the modern genomic era, new technologies involving gene therapy and genetic testing present both promise and fear. The ability to modify or select genes reawakens many of the same moral dilemmas that eugenics once posed. From a biological anthropological perspective, the danger lies not in studying or applying genetics itself, but in assuming that genes alone determine destiny. The human ecosystem operates within systems where culture, environment, and biology continuously interact; attempts to reduce behaviour, intelligence, or worth to genetic codes ignore these relationships that define humanity.<\/p>\n<p>As Steven Pinker argues when commenting on his book <em>The Blank Slate<\/em>, there have been two ideologies that have led to genocide: eugenics and Marxism. Marxism disregarded the idea of biology and race as well as human nature. Thus, it is not solely inheritance (genes) that leads to genocide, but the overall belief that humanity can and should be remade through coercive means. Biological anthropology reminds us that human variation\u2014both cultural and genetic\u2014is the foundation of adaptability. To purposely limit diversity through selective reproduction or genetic homogenization is to weaken humans\u2019 capacity to evolve, both biologically and ethically.<\/p>\n<h4>Discussion questions<\/h4>\n<ul>\n<li>What are the limits in parental selection for an offspring\u2019s genetics?<\/li>\n<li>Consider the 1-child policy in China. What are some of the problems engendered by that policy?<\/li>\n<\/ul>\n<div class=\"textbox shaded\">\n<h2 class=\"import-Normal\">Review Questions<\/h2>\n<ul>\n<li class=\"import-Normal\">What is the purpose of DNA replication? Explain in a few sentences what happens during DNA replication. When do DNA mutations happen? And how does this create phenotypic variation (i.e., different phenotypes of the same physical trait)?<\/li>\n<li class=\"import-Normal\">Using your own words, what are homologous chromosomes and sister chromatids? What are the key differences between mitosis and meiosis?<\/li>\n<li class=\"import-Normal\">Determine if the pedigree diagram below (Figure 4.40) represents an autosomal dominant, autosomal recessive, or X-linked recessive pattern of inheritance. You should write the genotype (i.e., AA, Aa, or aa) above each square to help you (note: there may sometimes be two possible answers for a square\u2019s genotype). Please also explain why you concluded a particular pattern of inheritance.<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n<figure style=\"width: 247px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image36.png\" alt=\"Pedigree where 6 of 15 individuals have the trait. On 2 separate branches parents without the trait have a biological child who does.\" width=\"247\" height=\"214\" \/><figcaption class=\"wp-caption-text\">Figure 4.40: A four generation pedigree depicting a trait with an undetermined inheritance pattern. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-9\/\" target=\"_blank\">X-linked recessive pattern of inheritance (Figure 3.46)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Beth Shook is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<ul>\n<li class=\"import-Normal\">Use base pairing rules to transcribe the following DNA template sequence into mRNA: GTAAAGGTGCTGGCCATC. Next, use the protein codon table (see Figure 4.21) to translate the sequence. In regard to transcription, explain what the significance is of the first and last codon\/protein in the sequence.<\/li>\n<li class=\"import-Normal\">In your opinion, what do you think the benefits are of direct-to-consumer (DTC) genetic testing? What are the drawbacks and\/or greater ethical concerns? Do you think benefits outweigh concerns?<\/li>\n<li class=\"import-Normal\">Imagine that you submit your DNA sample to a genetic testing company and among the various diseases for which they test, there is an allele that is associated with late-onset Alzheimer\u2019s disease. You have the option to view your Alzheimer\u2019s result or to not view your result. What do you do and why?<\/li>\n<\/ul>\n<\/div>\n<h2 class=\"import-Normal\">Key Terms<\/h2>\n<p class=\"import-Normal\"><strong>Adenosine triphosphate (ATP)<\/strong>: A high-energy compound produced by mitochondria that powers cellular processes.<\/p>\n<p class=\"import-Normal\"><strong>Allele<\/strong>: A nonidentical DNA sequence found in the same gene location on a homologous chromosome, or gene copy, that codes for the same trait but produces a different phenotype.<\/p>\n<p class=\"import-Normal\"><strong>Amino acids<\/strong>: Organic molecules that are the building blocks of protein. Each of the 20 different amino acids have their own unique chemical property. Amino acids are chained together to form proteins.<\/p>\n<p class=\"import-Normal\"><strong>Ancient DNA (aDNA)<\/strong>: DNA that is extracted from organic remains and that often dates from hundreds to thousands of years ago. Also, aDNA is typically degraded (i.e., damaged) due to exposure to the elements such as heat, acidity, and humidity.<\/p>\n<p class=\"import-Normal\"><strong>Aneuploid<\/strong>: A cell with an unexpected amount of chromosomes. The loss or gain of chromosomes can occur during mitotic or meiotic division.<\/p>\n<p class=\"import-Normal\"><strong>Antibodies<\/strong>: Immune-related proteins that can detect and bind to foreign substances in the blood such as pathogens.<\/p>\n<p class=\"import-Normal\"><strong>Apoptosis<\/strong>: A series of molecular steps that is activated leading to cell death. Apoptosis can be activated when a cell fails checkpoints during the cell cycle; however, cancer cells have the ability to avoid apoptosis.<\/p>\n<p class=\"import-Normal\"><strong>Autosomal<\/strong>: Refers to a pattern of inheritance in which an allele is located on an autosome (non sex chromosome).<\/p>\n<p class=\"import-Normal\"><strong>Base pairs<\/strong>: Chemical bonding between nucleotides. In DNA, adenine (A) pairs with thymine (T) and cytosine (C) pairs with guanine (G); in RNA, adenine (A) always pairs with uracil (U).<\/p>\n<p class=\"import-Normal\"><strong>Carbohydrate<\/strong>: Molecules composed of carbon and hydrogen atoms that can be broken down to supply energy.<\/p>\n<p class=\"import-Normal\"><strong>Carrier<\/strong>: An individual who has a heterozygous genotype that is typically associated with a disease.<\/p>\n<p class=\"import-Normal\"><strong>Cell cycle<\/strong>: A cycle the cell undergoes with checkpoints between phases to ensure that DNA replication and cell division occur properly.<\/p>\n<p class=\"import-Normal\"><strong>Cell surface antigen<\/strong>: A protein that is found on a red blood cell\u2019s surface.<\/p>\n<p class=\"import-Normal\"><strong>Centromere<\/strong>: A structural feature that is defined as the \u201ccenter\u201d of a chromosome and that creates two different arm lengths. This term also refers to the region of attachment for microtubules during mitosis and meiosis.<\/p>\n<p class=\"import-Normal\"><strong>Chromatin<\/strong>: DNA wrapped around histone complexes. During cell division, chromatin becomes a condensed chromosome.<\/p>\n<p class=\"import-Normal\"><strong>Chromosome<\/strong>: DNA molecule that is wrapped around protein complexes, including histones.<\/p>\n<p class=\"import-Normal\"><strong>Codominance<\/strong>: The effects of both alleles in a genotype can be seen in the phenotype.<\/p>\n<p class=\"import-Normal\"><strong>Codons<\/strong>: A sequence that comprises three DNA nucleotides that together code for a protein.<\/p>\n<p class=\"import-Normal\"><strong>Complex diseases<\/strong>: A category of diseases that are polygenic and are also influenced by environment and lifestyle factors.<\/p>\n<p class=\"import-Normal\"><strong>Cytoplasm<\/strong>: The \u201cjelly-like\u201d matrix inside of the cell that contains many organelles and other cellular molecules.<\/p>\n<p class=\"import-Normal\"><strong>Deleterious<\/strong>: A mutation that increases an organism\u2019s susceptibility to disease.<\/p>\n<p class=\"import-Normal\"><strong>Deoxyribonucleic acid (DNA)<\/strong>: A molecule that carries the hereditary information passed down from parents to offspring. DNA can be described as a \u201cdouble helix\u201d\u2019 shape. It includes two chains of nucleotides held together by hydrogen bonds with a sugar phosphate backbone.<\/p>\n<p class=\"import-Normal\"><strong>Diploid<\/strong>: Refers to an organism or cell with two sets of chromosomes.<\/p>\n<p class=\"import-Normal\"><strong>DNA methylation<\/strong>: Methyl groups bind DNA, which modifies the transcriptional activity of a gene by turning it \u201con\u201d or \u201coff.\u201d<\/p>\n<p class=\"import-Normal\"><strong>DNA polymerase<\/strong>: Enzyme that adds nucleotides to existing nucleic acid strands during DNA replication. These enzymes can be distinguished by their processivity (e.g., DNA replication).<\/p>\n<p class=\"import-Normal\"><strong>DNA replication<\/strong>: Cellular process in which DNA is copied and doubled.<\/p>\n<p class=\"import-Normal\"><strong>DNA sequence<\/strong>: The order of nucleotide bases. A DNA sequence can be short, long, or representative of entire chromosomes or organismal genomes.<\/p>\n<p class=\"import-Normal\"><strong>Dominant<\/strong>: Refers to an allele for which one copy is sufficient to be visible in the phenotype.<\/p>\n<p class=\"import-Normal\"><strong>Elongation<\/strong>: The assembly of new DNA from template strands with the help of DNA polymerases.<\/p>\n<p class=\"import-Normal\"><strong>Enzymes<\/strong>: Proteins responsible for catalyzing (accelerating) various biochemical reactions in cells.<\/p>\n<p class=\"import-Normal\"><strong>Epigenetic profile<\/strong>: The methylation pattern throughout a genome\u2014that is, which genes (and other genomic sites) are methylated and unmethylated.<\/p>\n<p class=\"import-Normal\"><strong>Epigenetics<\/strong>: Changes in gene expression that do not result in a change of the underlying DNA sequence. These changes typically involve DNA methylation and histone modifications. These changes are reversible and can also be inherited by the next generation.<\/p>\n<p class=\"import-Normal\"><strong>Euchromatin<\/strong>: Loosely coiled chromosomes found within the nucleus that are accessible for regulatory processing of DNA.<\/p>\n<p class=\"import-Normal\"><strong>Eukaryote<\/strong>: Single-celled or multicelled organism characterized by a distinct nucleus, with each organelle surrounded by its own membrane.<\/p>\n<p class=\"import-Normal\"><strong>Exon<\/strong>: Protein-coding segment of a gene.<\/p>\n<p class=\"import-Normal\"><strong>Gametes<\/strong>: Haploid cells referred to as an egg and sperm that will fuse together during sexual reproduction to form a diploid organism.<\/p>\n<p class=\"import-Normal\"><strong>Gene<\/strong>: Segment of DNA that contains protein-coding information and various regulatory (e.g., promoter) and noncoding (e.g., introns) regions.<\/p>\n<p class=\"import-Normal\"><strong>Genetic recombination<\/strong>: A cellular process that occurs during meiosis I in which homologous chromosomes pair up and sister chromatids on different chromosomes physically swap genetic information.<\/p>\n<p class=\"import-Normal\"><strong>Genome<\/strong>: All the genetic information of an organism.<\/p>\n<p class=\"import-Normal\"><strong>Genotype<\/strong>: The combination of two alleles that code for or are associated with the same gene.<\/p>\n<p class=\"import-Normal\"><strong>Genotyping<\/strong>: A molecular procedure that is performed to test for the presence of certain alleles or to discover new ones.<\/p>\n<p class=\"import-Normal\"><strong>Germ cells<\/strong>: Specialized cells that form gametes (egg and sperm cells).<\/p>\n<p class=\"import-Normal\"><strong>Haploid<\/strong>: Cell or organism with one set of chromosomes (<em>n<\/em> = 23).<\/p>\n<p class=\"import-Normal\"><strong>Helicase<\/strong>: A protein that breaks the hydrogen bonds that hold double-stranded DNA together.<\/p>\n<p class=\"import-Normal\"><strong>Heterozygous<\/strong>: Genotype that consists of two different alleles.<\/p>\n<p class=\"import-Normal\"><strong>Histones<\/strong>: Proteins that DNA wraps around to assist with DNA organization within the nucleus.<\/p>\n<p class=\"import-Normal\"><strong>Homologous chromosomes<\/strong>: A matching pair of chromosomes wherein one chromosome is maternally inherited and the other is paternally inherited.<\/p>\n<p class=\"import-Normal\"><strong>Homozygous<\/strong>: Genotype that consists of two identical alleles.<\/p>\n<p class=\"import-Normal\"><strong>Incomplete dominance<\/strong>: Heterozygous genotype that produces a phenotype that is a blend of both alleles.<\/p>\n<p class=\"import-Normal\"><strong>Initiation<\/strong>: The recruitment of proteins to separate DNA strands and begin DNA replication.<\/p>\n<p class=\"import-Normal\"><strong>Interphase<\/strong>: Preparatory period of the cell cycle when increased metabolic demand allows for DNA replication and doubling of the cell prior to cell division.<\/p>\n<p class=\"import-Normal\"><strong>Introns<\/strong>: Segment of DNA that does not code for proteins.<\/p>\n<p class=\"import-Normal\"><strong>Karyotyping<\/strong>: The microscopic procedure wherein the number of chromosomes in a cell is determined.<\/p>\n<p class=\"import-Normal\"><strong>Lagging strand<\/strong>: DNA template strand that is opposite to the leading strand during DNA replication. This strand is created in several disconnected sections and other enzymes fill in the missing nucleotide gaps between these sections.<\/p>\n<p class=\"import-Normal\"><strong>Leading strand<\/strong>: DNA template strand in which replication proceeds continuously.<\/p>\n<p class=\"import-Normal\"><strong>Lipids<\/strong>: Fatty acid molecules that serve various purposes in the cell, including energy storage, cell signaling, and structure.<\/p>\n<p class=\"import-Normal\"><strong>Meiosis<\/strong>: The process that gametes undergo to divide. The end of meiosis results in four haploid daughter cells.<\/p>\n<p class=\"import-Normal\"><strong>Mendelian genetics<\/strong>: A classification given to phenotypic traits that are controlled by a single gene.<\/p>\n<p class=\"import-Normal\"><strong>Messenger RNA (mRNA)<\/strong>: RNA molecule that is transcribed from DNA. Its tri-nucleotide codons are \u201cread\u201d by a ribosome to build a protein.<\/p>\n<p class=\"import-Normal\"><strong>Microarray technology<\/strong>: A genotyping procedure that utilizes a microarray chip, which is a collection of thousands of short nucleotide sequences attached to a solid surface that can probe genomic DNA.<\/p>\n<p class=\"import-Normal\"><strong>Microbiome<\/strong>: The collective genomes of the community of microorganisms that humans have living inside of their bodies.<\/p>\n<p class=\"import-Normal\"><strong>Mitochondrial DNA (mtDNA)<\/strong>: Circular DNA segment found in mitochondria that is inherited maternally.<\/p>\n<p class=\"import-Normal\"><strong>Mitochondrion<\/strong>: Specialized cellular organelle that is the site for energy production. It also has its own genome (mtDNA).<\/p>\n<p class=\"import-Normal\"><strong>Mitosis<\/strong>: The process that somatic cells undergo to divide. The end of mitosis results in two diploid daughter cells.<\/p>\n<p class=\"import-Normal\"><strong>Molecular anthropologists<\/strong>: Individuals who use molecular techniques (primarily genetics) to compare ancient and modern populations and to study living populations of humans and nonhuman primates.<\/p>\n<p class=\"import-Normal\"><strong>Molecular geneticists<\/strong>: Biologists that study the structure and function of genes.<\/p>\n<p class=\"import-Normal\"><strong>Mutation<\/strong>: A nucleotide sequence variation from the template DNA strand that can occur during replication. Mutations can also happen during recombination.<\/p>\n<p class=\"import-Normal\"><strong>Next-generation sequencing<\/strong>: A genotyping technology that involves producing millions of nucleotide sequences (from a single DNA sample) that are then read with a sequencing machine. It can be used for analyzing entire genomes or specific regions and requires extensive program-based applications.<\/p>\n<p class=\"import-Normal\"><strong>Nuclear envelope<\/strong>: A double-layered membrane that encircles the nucleus.<\/p>\n<p class=\"import-Normal\"><strong>Nucleic acid<\/strong>: A complex structure (like DNA or RNA) that carries genetic information about a living organism.<\/p>\n<p class=\"import-Normal\"><strong>Nucleotide<\/strong>: The basic structural component of nucleic acids, which includes DNA (A, T, C, and G) and RNA (A, U, C, and G).<\/p>\n<p class=\"import-Normal\"><strong>Nucleus<\/strong>: Double-membrane cellular organelle that helps protect DNA and also regulates nuclear activities.<\/p>\n<p class=\"import-Normal\"><strong>Organelle<\/strong>: A structure within a cell that performs specialized tasks that are essential for the cell. There are different types of organelles, each with its own function.<\/p>\n<p class=\"import-Normal\"><strong>Pathogenic<\/strong>: A genetic mutation (i.e., allele) that has a harmful phenotypic disease-causing effect.<\/p>\n<p class=\"import-Normal\"><strong>Pedigree<\/strong>: A diagram of family relationships that indicates which members may have or carry certain genetic and\/or phenotypic traits.<\/p>\n<p class=\"import-Normal\"><strong>Penetrance<\/strong>: The proportion of how often the possession of an allele results in an expected phenotype. Some alleles are more penetrant than others.<\/p>\n<p class=\"import-Normal\"><strong>Phenotype<\/strong>: The physical appearance of a given trait.<\/p>\n<p class=\"import-Normal\"><strong>Phospholipid bilayer<\/strong>: Two layers of lipids that form a barrier due to the properties of a hydrophilic (water-loving) head and a hydrophobic (water-repelling) tail.<\/p>\n<p class=\"import-Normal\"><strong>Polygenic trait<\/strong>: A phenotype that is controlled by two or more genes.<\/p>\n<p class=\"import-Normal\"><strong>Polymerase chain reaction (PCR)<\/strong>: A molecular biology procedure that can make copies of genomic DNA segments. A small amount of DNA is used as a starting template and is then used to make millions of copies.<\/p>\n<p class=\"import-Normal\"><strong>Prokaryote<\/strong>: A single-celled organism characterized by the lack of a nucleus and membrane-enclosed organelles.<\/p>\n<p class=\"import-Normal\"><strong>Promoter<\/strong>: The region of a gene that initiates transcription. Transcription factors can bind and DNA methylation may occur at a promoter site, which can modify the transcriptional activities of a gene.<\/p>\n<p class=\"import-Normal\"><strong>Protein<\/strong>: Chain of amino acids that folds into a three-dimensional structure that allows a cell to function in a variety of ways.<\/p>\n<p class=\"import-Normal\"><strong>Protein synthesis<\/strong>: A multi-step process by which amino acids are strung together by RNA machinery read from a DNA template.<\/p>\n<p class=\"import-Normal\"><strong>Recessive<\/strong>: Refers to an allele whose effect is not normally seen unless two copies are present in an individual\u2019s genotype.<\/p>\n<p class=\"import-Normal\"><strong>Ribonucleic acid (RNA)<\/strong>: Single-stranded nucleic acid molecule.There are different RNAs found within cells and they perform a variety of functions, such as cell signaling and involvement in protein synthesis.<\/p>\n<p class=\"import-Normal\"><strong>Ribosomal RNA (rRNA)<\/strong>: A ribosome-bound molecule that is used to correctly assemble amino acids into proteins.<\/p>\n<p class=\"import-Normal\"><strong>Ribosome<\/strong>: An organelle in the cell found in the cytoplasm or endoplasmic reticulum. It is responsible for reading mRNA and protein assemblage.<\/p>\n<p class=\"import-Normal\"><strong>RNA polymerase<\/strong>: An enzyme that catalyzes the process of making RNA from a DNA template.<\/p>\n<p class=\"import-Normal\"><strong>Sanger-sequencing<\/strong>: A process that involves the usage of fluorescently labeled nucleotides to visualize DNA (PCR fragments) at the nucleotide level.<\/p>\n<p class=\"import-Normal\"><strong>Semi-conservative replication<\/strong>: DNA replication in which new DNA is replicated from an existing DNA template strand.<\/p>\n<p class=\"import-Normal\"><strong>Sequencing<\/strong>: A molecular laboratory procedure that produces the order of nucleotide bases (i.e., sequences).<\/p>\n<p class=\"import-Normal\"><strong>Sister chromatids<\/strong>: During DNA replication, sister chromatids are produced on the chromosome. In cell division, sister chromatids are pulled apart so that two cells can be formed. In meiosis, sister chromatids are also the sites of genetic recombination.<\/p>\n<p class=\"import-Normal\"><strong>Somatic cells<\/strong>: Diploid cells that comprise body tissues and undergo mitosis for maintenance and repair of tissues.<\/p>\n<p class=\"import-Normal\"><strong>Splicing<\/strong>: The process by which mature mRNAs are produced. Introns are removed (spliced) and exons are joined together.<\/p>\n<p class=\"import-Normal\"><strong>Sugar phosphate backbone<\/strong>: A biochemical structural component of DNA. The \u201cbackbone\u201d consists of deoxyribose sugars and phosphate molecules.<\/p>\n<p class=\"import-Normal\"><strong>Telomere<\/strong>: A compound structure located at the ends of chromosomes to help protect the chromosomes from degradation after every round of cell division.<\/p>\n<p class=\"import-Normal\"><strong>Termination<\/strong>: The halt of DNA replication activity that occurs when a DNA sequence \u201cstop\u201d codon is encountered.<\/p>\n<p class=\"import-Normal\"><strong>Tissue<\/strong>: A cluster of cells that are morphologically similar and perform the same task.<\/p>\n<p class=\"import-Normal\"><strong>Transcription<\/strong>: The process by which DNA nucleotides (within a gene) are copied, which results in a messenger RNA molecule.<\/p>\n<p class=\"import-Normal\"><strong>Transcription factors<\/strong>: Proteins that bind to regulatory regions of genes (e.g., promoter) and increase or decrease the amount of transcriptional activity of a gene, including turning them \u201con\u201d or \u201coff.\u201d<\/p>\n<p class=\"import-Normal\"><strong>Transfer RNA (tRNA)<\/strong>: RNA molecule involved in translation. Transfer RNA transports amino acids from the cell\u2019s cytoplasm to a ribosome.<\/p>\n<p class=\"import-Normal\"><strong>Translation<\/strong>: The process by which messenger RNA codons are read and amino acids are \u201cchained together\u201d to form proteins.<\/p>\n<p class=\"import-Normal\"><strong>X-linked<\/strong>: Refers to a pattern of inheritance where the allele is located on the X or Y chromosome.<\/p>\n<h2 class=\"import-Normal\">For Further Exploration<\/h2>\n<p class=\"import-Normal\"><a href=\"https:\/\/www.genome.gov\/\" target=\"_blank\">National Human Genome Research Institute<\/a><\/p>\n<p class=\"import-Normal\"><a href=\"https:\/\/ghr.nlm.nih.gov\/\" target=\"_blank\">Genetics Home Reference<\/a><\/p>\n<p class=\"import-Normal\"><a href=\"https:\/\/knowgenetics.org\/\" target=\"_blank\">Genetics Generation<\/a><\/p>\n<p class=\"import-Normal\"><a href=\"https:\/\/www.yourgenome.org\/\" target=\"_blank\">yourgenome<\/a><\/p>\n<p class=\"import-Normal\">NOVA. 2018. Gene Sequencing Speeds Diagnosis of Deadly Newborn Diseases. NOVA, March 7, 2018. Accessed January 31, 2023. <a class=\"rId164\" href=\"https:\/\/www.pbs.org\/wgbh\/nova\/next\/body\/newborn-gene-sequencing\/\" target=\"_blank\">https:\/\/www.pbs.org\/wgbh\/nova\/next\/body\/newborn-gene-sequencing\/<\/a>.<\/p>\n<p class=\"import-Normal\">Zimmer, Carl. N.d. \u201cCarl Zimmer\u2019s Game of Genomes.\u201d STATnews. Accessed January 31, 2023. <a class=\"rId165\" href=\"https:\/\/www.statnews.com\/feature\/game-of-genomes\/season-one\/\" target=\"_blank\">https:\/\/www.statnews.com\/feature\/game-of-genomes\/season-one\/<\/a>.<\/p>\n<p class=\"import-Normal\">Illumina. 2016. \u201cIllumina Sequencing by Synthesis.\u201d YouTube.com, October 5, 2016. Accessed January 31, 2023. <a class=\"rId166\" href=\"https:\/\/www.youtube.com\/watch?v=fCd6B5HRaZ8\" target=\"_blank\">https:\/\/www.youtube.com\/watch?v=fCd6B5HRaZ8<\/a>.<\/p>\n<h2 class=\"import-Normal\">References<\/h2>\n<p class=\"import-Normal\">Aartsma-Rus, Annemieke, Ieke B. Ginjaar, and Kate Bushby. 2016. \u201cThe Importance of Genetic Diagnosis for Duchenne Muscular Dystrophy.\u201d Journal of Medical Genetics 53 (3): 145\u2013151.<\/p>\n<p class=\"import-Normal\">Acuna-Hidalgo, Rocio, Joris A. Veltman, and Alexander Hoischen. 2016. \u201cNew Insights into the Generation and Role of De Novo Mutations in Health and Disease.\u201d Genome Biology 17 (241): 1\u201319.<\/p>\n<p class=\"import-Normal\">Albert, Benjamin, Susanna Tomassetti, Yvonne Gloor, Daniel Dilg, Stefano Mattarocci, Slawomir Kubik, Lukas Hafner, and David Shore. 2019. \"Sfp1 Regulates Transcriptional Networks Driving Cell Growth and Division through Multiple Promoter-Binding Modes.\" Genes &amp; Development 33 (5\u20136): 288\u2013293.<\/p>\n<p class=\"import-Normal\">Almathen, Faisal, Haitham Elbir, Hussain Bahbahani, Joram Mwacharo, and Olivier Hanotte. 2018. \u201cPolymorphisms in Mc1r and Asip Genes Are Associated with Coat Color Variation in the Arabian Camel.\u201d Journal of Heredity 109 (6): 700\u2013706.<\/p>\n<p class=\"import-Normal\">Ballester, Leomar Y., Rajyalakshmi Luthra, Rashmi Kanagal-Shamanna, and Rajesh R. Singh. 2016. \u201cAdvances in Clinical Next-Generation Sequencing: Target Enrichment and Sequencing Technologies.\u201d Expert Review of Molecular Diagnostics 16 (3): 357\u2013372.<\/p>\n<p class=\"import-Normal\">Baranovskiy, Andrey G., Vincent N. Duong, Nigar D. Babayeva, Yinbo Zhang, Youri I. Pavlov, Karen S. Anderson, and Tahir H. Tahirov. 2018. \u201cActivity and Fidelity of Human DNA Polymerase Alpha Depend on Primer Structure.\u201d Journal of Biological Chemistry 293 (18): 6824\u20136843.<\/p>\n<p>Biswas, S., Ghosh, S., Das, S., &amp; Maitra, S. (2021). Female Reproduction: At the Crossroads of Endocrine Disruptors and Epigenetics. Proceedings of the Zoological Society, 74(4), 532\u2013545. <a href=\"https:\/\/doi.org\/10.1007\/s12595-021-00403-4\" target=\"_blank\">https:\/\/doi.org\/10.1007\/s12595-021-00403-4<\/a><\/p>\n<p class=\"import-Normal\">Brezina, Paulina R., Raymond Anchan, and William G. Kearns. 2016. \u201cPreimplantation Genetic Testing for Aneuploidy: What Technology Should You Use and What Are the Differences?\u201d Journal of Assisted Reproduction and Genetics 33 (7): 823\u2013832.<\/p>\n<p class=\"import-Normal\">Bultman, Scott J. 2017. \u201cInterplay Between Diet, Gut Microbiota, Epigenetic Events, and Colorectal Cancer.\" Molecular Nutrition &amp; Food Research 61 (1):1\u201312.<\/p>\n<p class=\"import-Normal\">Cutting, Garry R. 2015. \u201cCystic Fibrosis Genetics: From Molecular Understanding to Clinical Application.\u201d Nature Reviews Genetics 16 (1): 45\u201356.<\/p>\n<p class=\"import-Normal\">D'Alessandro, Giuseppina., and Fabrizio d'Adda di Fagagna. 2017. \u201cTranscription and DNA Damage: Holding Hands or Crossing Swords?\u201d Journal of Molecular Biology 429 (21): 3215\u20133229.<\/p>\n<p class=\"import-Normal\">De Craene, Johan-Owen, Dimitri L. 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Zaykin, Marc Parisien, Simon Gravel, Andrey Bortsov, and Luda Diatchenko. 2019. \u201cA Study in Scarlet: MC1R as the Main Predictor of Red Hair and Exemplar of the Flip-Flop Effect.\u201d Human Molecular Genetics 28 (12): 2093-2106.<\/p>\n<p class=\"import-Normal\">Zwart, Haeh. 2018. \u201cIn the Beginning Was the Genome: Genomics and the Bi-Textuality of Human Existence.\u201d New Bioethics 24 (1): 26\u201343.<\/p>\n<\/div>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1695_1849\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1695_1849\"><div tabindex=\"-1\"><div class=\"__UNKNOWN__\">\n<div class=\"textbox\">\n<h6>Student contributors for this chapter from Salinda Hess' ANTH 203: Corin Laberge, Hazel Moorcroft, Isabella Michel, Julian J. Pantoja Quiroz<\/h6>\n<p>Learn more about <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/about-the-authors\/\">authors and editors<\/a>,<a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/student-contributors\/\"> Hess' student contributions<\/a>, and <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/versioning-history\/\">versioning history<\/a>.<\/p>\n<\/div>\n<div class=\"textbox textbox--learning-objectives\">\n<header class=\"textbox__header\">\n<h2 class=\"textbox__title\">Learning Objectives<\/h2>\n<\/header>\n<div class=\"textbox__content\">\n<ul>\n<li class=\"import-Normal\">Outline a 21st-century perspective of the Modern Synthesis.<\/li>\n<li class=\"import-Normal\">Define populations and population genetics as well as the methods used to study them.<\/li>\n<li class=\"import-Normal\">Identify the forces of evolution and become familiar with examples of each.<\/li>\n<li class=\"import-Normal\">Discuss the evolutionary significance of mutation, genetic drift, gene flow, and natural selection.<\/li>\n<li class=\"import-Normal\">Explain how allele frequencies can be used to study evolution as it happens.<\/li>\n<li class=\"import-Normal\">Contrast micro- and macroevolution.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<p>It\u2019s hard for us, with our typical human life spans of less than 100 years, to imagine all the way back, 3.8 billion years ago, to the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1442\">origins of life<\/a><\/strong>. Scientists still study and debate how life came into being and whether it originated on Earth or in some other region of the universe (including some scientists who believe that studying evolution can reveal the complex processes that were set in motion by God or a higher power). What we do know is that a living single-celled organism was present on Earth during the early stages of our planet\u2019s existence. This organism had the potential to reproduce by making copies of itself, just like bacteria, many amoebae, and our own living cells today. In fact, with modern technologies, we can now trace genetic lineages, or <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1290\">phylogenies<\/a><\/strong>, and determine the relationships between all of today\u2019s living organisms\u2014eukaryotes (animals, plants, fungi, etc.), archaea, and bacteria\u2014on the branches of the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1444\">phylogenetic tree of life<\/a><\/strong> (Figure 5.1).<\/p>\n<figure style=\"width: 675px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2023\/02\/image1-1.png\" alt=\"Branches lead off of a single celled universal ancestor to images of bacteria, archaea, and eukarya (represented by a mouse, mushroom, and fern, among others).\" width=\"675\" height=\"475\" \/><figcaption class=\"wp-caption-text\">Figure 5.1: Phylogenetic tree of life illustrating probable relationships between the single-celled Last Universal Common Ancestor (LUCA) and select examples of bacteria, archaea, and eukaryotes. Major evolutionary developments, including independent evolution of multicellularity, photosynthesis, and respiration, are indicated along the branches. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available<\/a>. Credit: <a class=\"rId11\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Cladograma_dos_Dom%C3%ADnios_e_Reinos.png\" target=\"_blank\">Cladograma dos Dominios e Reinos<\/a> by <a class=\"rId12\" href=\"https:\/\/commons.wikimedia.org\/wiki\/User:MarceloTeles\" target=\"_blank\">MarceloTeles<\/a> has been modified (English labels replace Portuguese) and is under a <a class=\"rId13\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/deed.en\" target=\"_blank\">CC BY-SA 4.0 License<\/a>..<\/figcaption><\/figure>\n<p class=\"import-Normal\">Looking at the common sequences in modern genomes, we can even make educated guesses about the likely genetic sequence of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1446\"><strong>Last Universal Common Ancestor (LUCA)<\/strong><\/a> of all living things. Through a wondrous series of mechanisms and events over nearly four billion years, that ancient single-celled organism gave rise to the rich diversity of species that fill the lands, seas, and skies of our planet. This chapter explores the mechanisms by which that amazing transformation occurred and considers some of the crucial scientific experiments that shaped our current understanding of the evolutionary process.<\/p>\n<h2 class=\"import-Normal\">Population Genetics<\/h2>\n<h3 class=\"import-Normal\"><strong>Defining Populations and the Variations <\/strong><strong>w<\/strong><strong>ithin Them<\/strong><\/h3>\n<p class=\"import-Normal\">One of the major breakthroughs in understanding the mechanisms of evolutionary change came with the realization that evolution takes place at the level of populations, not within individuals. In the biological sciences, a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1454\"><strong>p<\/strong><strong>opulation<\/strong><\/a> is defined as a group of individuals of the same <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1456\"><strong>species<\/strong><\/a> who are geographically near enough to one another that they can breed and produce new generations of individuals.<\/p>\n<p class=\"import-Normal\">For the purpose of studying evolution, we recognize populations by their even smaller units: genes. Remember, a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1458\"><strong>gene<\/strong><\/a> is the basic unit of information that encodes the proteins needed to grow and function as a living organism. Each gene can have multiple <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_738\">alleles<\/a><\/strong>, or variants\u2014each of which may produce a slightly different protein. Each individual, for genetic inheritance purposes, carries a collection of genes that can be passed down to future generations. For this reason, in population genetics, we think of populations as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1462\"><strong>gene pools<\/strong><\/a>, which refers to the entire collection of genetic material in a breeding community that can be passed on from one generation to the next.<\/p>\n<p class=\"import-Normal\">For genes carried on our human chromosomes (our nuclear DNA), we inherit two copies of each, one from each parent. This means we may carry two of the same alleles (a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1464\"><strong>homozygous genotype<\/strong><\/a>) or two different alleles (a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1466\"><strong>heterozygous<\/strong> <strong>genotype<\/strong><\/a>) for each nuclear gene.<\/p>\n<h3 class=\"import-Normal\"><strong>Defining Evolution <\/strong><\/h3>\n<p class=\"import-Normal\">In order to understand evolution, it\u2019s crucial to remember that evolution is always studied at the population level. Also, if a population were to stay exactly the same from one generation to the next, it would not be evolving. So evolution requires both a population of breeding individuals and some kind of a genetic change occurring within it. Thus, the simple definition of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1468\"><strong>evolution<\/strong><\/a> is a change in the allele frequencies in a population over time. What do we mean by allele frequencies? <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1470\"><strong>Allele frequencies<\/strong> <\/a>refer to the ratio, or percentage, of one allele (one variant of a gene) compared to the other alleles for that gene within the study population (Figure 5.2). By contrast, <strong>genotype frequencies<\/strong> are the ratios or percentages of the different homozygous and heterozygous genotypes in the population. Because we carry two alleles per <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_736\">genotype<\/a><\/strong>, the total count of alleles in a population will usually be exactly double the total count of genotypes in the same population (with the exception being rare cases in which an individual carries a different number of chromosomes than the typical two; e.g., Down syndrome results when a child carries three copies of Chromosome 21).<\/p>\n<figure style=\"width: 652px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image2.jpg\" alt=\"Genotypes are represented as combinations of alleles and allele frequencies.\" width=\"652\" height=\"883\" \/><figcaption class=\"wp-caption-text\">Figure 5.2: Population evolution can be measured by allele frequency changes. This diagram illustrates the differences between genotype frequencies and allele frequencies, as well as how they can be measured in a population of snapdragon flowers. The lower portion of the diagram also depicts how evolution is recognized as allele frequencies change in a population over time. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available<\/a>. Credit: Population evolution original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Katie Nelson and Beth Shook is a collective work under a <a class=\"rId15\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\" target=\"_blank\">CC BY-NC 4.0 License<\/a>. [Includes <a class=\"rId16\" href=\"https:\/\/pixabay.com\/vectors\/snapdragon-flower-pink-lilac-plant-146850\/\" target=\"_blank\">Snapdragon-flower-pink-lilac<\/a> by <a class=\"rId17\" href=\"https:\/\/pixabay.com\/users\/openclipart-vectors-30363\/\" target=\"_blank\">OpenClipart-Vectors<\/a>, <a class=\"rId18\" href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/cc0\/\" target=\"_blank\">public domain (CC0)<\/a> under a <a class=\"rId19\" href=\"https:\/\/pixabay.com\/service\/terms\/\" target=\"_blank\">Pixabay License<\/a>.]<\/figcaption><\/figure>\n<h2 class=\"import-Normal\">The Forces of Evolution<\/h2>\n<p class=\"import-Normal\">Today, we recognize that evolution takes place through a combination of mechanisms: mutation, genetic drift, gene flow, and natural selection. These mechanisms are called the \u201cforces of evolution\u201d; together they account for all the genotypic variation observed in the world today. Keep in mind that each of these forces was first defined and then tested\u2014and retested\u2014through the experimental work of the many scientists who contributed to the Modern Synthesis.<\/p>\n<h3 class=\"import-Normal\"><strong>Mutation<\/strong><\/h3>\n<p class=\"import-Normal\">The first force of evolution we will discuss is mutation, and for good reason: mutation is the original source of all the genetic variation found in every living thing. Imagine all the way back in time to the very first single-celled organism, floating in Earth\u2019s primordial sea. Based on what we observe in simple, single-celled organisms today, that organism probably spent its lifetime absorbing nutrients and dividing to produce cloned copies of itself. While the numbers of individuals in that population would have grown (as long as the environment was favourable), nothing would have changed in that perfectly cloned population. There would not have been variety among the individuals. It was only through a copying error\u2014the introduction of a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1474\"><strong>mutation<\/strong><\/a>, or change, into the genetic code\u2014that new alleles were introduced into the population.<br style=\"clear: both\" \/><br style=\"clear: both\" \/>After many generations have passed in our primordial population, mutations have created distinct chromosomes. The cells are now amoeba-like, larger than many of their tiny bacterial neighbours, who have long since become their favourite source of nutrients. Without mutation to create this diversity, all living things would still be identical to LUCA, our universal ancestor (Figure 5.3).<\/p>\n<figure style=\"width: 663px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image3-2.png\" alt=\"Universal Ancestor linked to the Eukarya branch.\" width=\"663\" height=\"338\" \/><figcaption class=\"wp-caption-text\">Figure 5.3: Key mutational differences between Last Universal Common Ancestor and an amoeba-like primordial cell. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available<\/a>. Credit<strong>: <\/strong>Key differences between LUCA and a primordial cell original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Andrea J. Alveshere is a collective work under a <a class=\"rId21\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\" target=\"_blank\">CC BY-NC-SA 4.0 License<\/a>. [Includes <a class=\"rId22\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Cladograma_dos_Dom%C3%ADnios_e_Reinos.png\" target=\"_blank\">Cladograma dos Dominios e Reinos<\/a> by <a class=\"rId23\" href=\"https:\/\/commons.wikimedia.org\/wiki\/User:MarceloTeles\" target=\"_blank\">MarceloTeles<\/a> (cropped, labels and colour changed), <a class=\"rId24\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/deed.en\" target=\"_blank\">CC BY-SA 4.0<\/a><a class=\"rId25\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/deed.en\" target=\"_blank\">; <\/a><a class=\"rId26\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Amoeba_proteus_TK-UT.svg\" target=\"_blank\">Amoeba Proteus TK-UT<\/a> by <a class=\"rId27\" href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Nefronus\" target=\"_blank\">Tom\u00e1\u0161 Kebert<\/a> and <a class=\"rId28\" href=\"https:\/\/www.umimeto.org\/\" target=\"_blank\">umimeto.org<\/a> (cropped and colour changed), <a class=\"rId29\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/deed.en\" target=\"_blank\">CC BY-SA 4.0<\/a>.]<\/figcaption><\/figure>\n<p class=\"import-Normal\">When we think of genetic mutation, we often first think of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1476\">deleterious mutations<\/a><\/strong>\u2014the ones associated with negative effects such as the beginnings of cancers or heritable disorders. The fact is, though, that every genetic adaptation that has helped our ancestors survive since the dawn of life is directly due to <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1478\">beneficial mutations<\/a><\/strong>\u2014changes in the DNA that provided some sort of advantage to a given population at a particular moment in time. For example, a beneficial mutation allowed chihuahuas and other tropical-adapted dog breeds to have much thinner fur coats than their cold-adapted cousins the northern wolves, malamutes, and huskies.<\/p>\n<figure style=\"width: 320px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image4-1-1.png\" alt=\"UV radiation damages nucleotides in DNA.\" width=\"320\" height=\"248\" \/><figcaption class=\"wp-caption-text\">Figure 5.4: A crosslinking mutation in which a UV photon induces a bond between two thymine bases. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available<\/a>. Credit<strong>: <\/strong><a class=\"rId31\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-3\/\" target=\"_blank\">UV-induced Thymine dimer mutation (Figure 4.6)<\/a> original to <a class=\"rId32\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a class=\"rId33\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Every one of us has genetic mutations. Yes, even you. The DNA in some of your cells today differs from the original DNA that you inherited when you were a tiny, fertilized egg. Mutations occur all the time in the cells of our skin and other organs, due to chemical changes in the nucleotides. Exposure to the UV radiation in sunlight is one common cause of skin mutations. Interaction with UV light causes <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1480\"><strong>UV crosslinking<\/strong><\/a>, in which adjacent thymine bases bind with one another (Figure 5.4). Many of these mutations are detected and corrected by <strong>DNA repair mechanisms<\/strong>, enzymes that patrol and repair DNA in living cells, while other mutations may cause a new freckle or mole or, perhaps, an unusual hair to grow. For people with the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1484\">autosomal recessive<\/a><\/strong> disease <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1486\"><strong>xeroderma pigmentosum<\/strong><\/a>, these repair mechanisms do not function correctly, resulting in a host of problems especially related to sun exposure, including severe sunburns, dry skin, heavy freckling, and other pigment changes.<\/p>\n<p class=\"import-Normal\">Most of our mutations exist in <strong>somatic<\/strong> cells, which are the cells of our organs and other body tissues. Those will not be passed onto future generations and so will not affect the population over time. Only mutations that occur in the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_686\">gametes<\/a><\/strong>, the reproductive cells (i.e., the sperm or egg cells), will be passed onto future generations. When a new mutation pops up at random in a family lineage, it is known as a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1490\"><strong>spontaneous mutation<\/strong><\/a>. If the individual born with this spontaneous mutation passes it on to his offspring, those offspring receive an <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1492\">inherited mutation<\/a><\/strong>. Geneticists have identified many classes of mutations and the causes and effects of many of these.<\/p>\n<h4 class=\"import-Normal\"><em>Point Mutations<\/em><\/h4>\n<p class=\"import-Normal\">A <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1494\">point mutation<\/a><\/strong> is a single-letter (single-nucleotide) change in the genetic code resulting in the substitution of one nucleic acid base for a different one. As you learned in Chapter 4, the DNA code in each gene is translated through three-letter \u201cwords\u201d known as <strong>codons<\/strong>. So depending on how the point mutation changes the \u201cword,\u201d the effect it will have on the protein may be major or minor or may make no difference at all.<\/p>\n<p class=\"import-Normal\">If a mutation does not change the resulting protein, then it is called a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1496\">synonymous mutation<\/a><\/strong>. Synonymous mutations do involve a letter (nucleic acid) change, but that change results in a codon that codes for the same \u201cinstruction\u201d (the same amino acid or stop code) as the original codon. Mutations that do cause a change in the protein are known as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1498\"><strong>nonsynonymous mutations<\/strong>.<\/a> Nonsynonymous mutations may change the resulting protein\u2019s amino acid sequence by altering the DNA sequence that encodes the mRNA or by changing how the mRNA is spliced prior to translation (refer to Chapter 4 for more details).<\/p>\n<h4 class=\"import-Normal\"><em>Insertions and Deletions<\/em><\/h4>\n<p class=\"import-Normal\">In addition to point mutations, another class of mutations are <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1500\"><strong>insertions<\/strong><\/a> and <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1504\">deletions<\/a><\/strong>, or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1502\"><strong>indels<\/strong><\/a>, for short. As the name suggests, these involve the addition (insertion) or removal (deletion) of one or more coding sequence letters (nucleic acids). These typically first occur as an error in DNA replication, wherein one or more nucleotides are either duplicated or skipped in error. Entire codons or sets of codons may also be removed or added if the indel is a multiple of three nucleotides.<\/p>\n<p class=\"import-Normal\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1506\"><strong>Frameshift<\/strong> <strong>mutations<\/strong><\/a> are types of indels that involve the insertion or deletion of any number of nucleotides that is not a multiple of three (e.g., adding one or two extra letters to the code). Because these indels are not consistent with the codon numbering, they \u201cshift the reading frame,\u201d causing all the codons beyond the mutation to be misread. Like point mutations, small indels can also disrupt splice sites.<\/p>\n<p class=\"import-Normal\"><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1508\">Transposable elements<\/a><\/strong>, or <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1510\">transposons<\/a><\/strong>, are fragments of DNA that can \u201cjump\u201d around in the genome. There are two types of transposons: <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1512\">retrotransposons<\/a><\/strong> are transcribed from DNA into RNA and then \u201creverse transcribed,\u201d to insert the copied sequence into a new location in the DNA, and<strong> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1514\">DNA transposons<\/a><\/strong>, which do not involve RNA. DNA transposons are clipped out of the DNA sequence itself and inserted elsewhere in the genome. Because transposable elements insert themselves into existing DNA sequences, they are frequent gene disruptors. At certain times, and in certain species, it appears that transposons became very active, likely accelerating the mutation rate (and thus, the genetic variation) in those populations during the active periods.<\/p>\n<h4 class=\"import-Normal\"><em>Chromosomal Alterations <\/em><\/h4>\n<p class=\"import-Normal\">The final major category of genetic mutations are changes at the chromosome level: crossover events, nondisjunction events, and translocations. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1516\"><strong>Crossover events<\/strong> <\/a> occur when DNA is swapped between homologous chromosomes while they are paired up during meiosis I. Crossovers are thought to be so common that some DNA swapping may happen every time chromosomes go through meiosis I. Crossovers don\u2019t necessarily introduce new alleles into a population, but they do make it possible for new combinations of alleles to exist on a single chromosome that can be passed to future generations. This also enables new combinations of alleles to be found within siblings who share the same parents. Also, if the fragments that cross over don\u2019t break at exactly the same point, they can cause genes to be deleted from one of the homologous chromosomes and duplicated on the other.<\/p>\n<p class=\"import-Normal\"><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1518\">Nondisjunction events<\/a><\/strong> occur when the homologous chromosomes (in meiosis I) or sister chromatids (in meiosis II and mitosis) fail to separate after pairing. The result is that both chromosomes or chromatids end up in the same daughter cell, leaving the other daughter cell without any copy of that chromosome (Figure 5.5). Most nondisjunctions at the gamete level are fatal to the embryo. The most widely known exception is Trisomy 21, or Down syndrome, which results when an embryo inherits three copies of Chromosome 21: two from one parent (due to a nondisjunction event) and one from the other (Figure 5.6). <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1520\">Trisomies<\/a> <\/strong>(triple chromosome conditions) of Chromosomes 18 (Edwards syndrome) and 13 (Patau syndrome) are also known to result in live births, but the children usually have severe complications and rarely survive beyond the first year of life.<\/p>\n<figure style=\"width: 601px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image5.jpg\" alt=\"Egg cell undergoes normal meiosis and nondisjunction in meisosis 1.\" width=\"601\" height=\"391\" \/><figcaption class=\"wp-caption-text\">Figure 5.5: Illustration of an egg cell (oocyte) undergoing normal meiosis 1, resulting in a diploid daughter cell, compared to an egg cell undergoing nondisjunction during meiosis 1, resulting in a trisomy in the daughter cell. Credit: <a class=\"rId35\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Trisomy_due_to_nondisjunction_in_maternal_meiosis_1.png\" target=\"_blank\">Trisomy due to nondisjunction in maternal meiosis 1<\/a> by Wpeissner has been modified (labels deleted by Katie Nelson) and is under a <a class=\"rId36\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\" target=\"_blank\">CC BY-NC-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<figure style=\"width: 316px\" class=\"wp-caption alignright\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image6-1.jpg\" alt=\"A young woman in a blue polo shirt smiles at the camera.\" width=\"316\" height=\"364\" \/><figcaption class=\"wp-caption-text\">Figure 5.6: Amy Bockerstette, a competitive golfer and disabilities advocate, also has Down Syndrome. Credit: <a class=\"rId38\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Amy_Bockerstette_Headshot.jpg\" target=\"_blank\">Amy Bockerstette Headshot<\/a> by Bucksgrandson is under a <a class=\"rId39\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\" target=\"_blank\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Sex chromosome trisomies (XXX, XXY, XYY) and X chromosome <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1522\"><strong>monosomies<\/strong> <\/a>(inheritance of an X chromosome from one parent and no sex chromosome from the other) are also survivable and fairly common. The symptoms vary but often include atypical sexual characteristics, either at birth or at puberty, and often result in sterility. The X chromosome carries unique genes that are required for survival; therefore, Y chromosome monosomies are incompatible with life.<\/p>\n<p class=\"import-Normal\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1524\"><strong>Chromosomal translocations<\/strong><\/a> involve transfers of DNA between nonhomologous chromosomes. This may involve swapping large portions of two or more chromosomes. The exchanges of DNA may be balanced or unbalanced. In <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1526\"><strong>balanced translocations<\/strong><\/a>, the genes are swapped, but no genetic information is lost. In <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1528\">unbalanced translocations<\/a><\/strong>, there is an unequal exchange of genetic material, resulting in duplication or loss of genes. Translocations result in new chromosomal structures called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1530\"><strong>derivative chromosomes<\/strong><\/a>, because they are derived or created from two different chromosomes<em>. <\/em>Translocations are often found to be linked to cancers and can also cause infertility. Even if the translocations are balanced in the parent, the embryo often won\u2019t survive unless the baby inherits both of that parent\u2019s derivative chromosomes (to maintain the balance).<\/p>\n<h3 class=\"import-Normal\"><strong>Genetic Drift<\/strong><\/h3>\n<p class=\"import-Normal\">The second force of evolution is commonly known as genetic drift. This is an unfortunate misnomer, as this force actually involves the drifting of alleles, not genes. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1532\"><strong>Genetic <\/strong><strong>d<\/strong><strong>rift<\/strong><\/a> refers to <em>random<\/em> changes (\u201cdrift\u201d) in allele frequencies from one generation to the next. The genes are remaining constant within the population; it is only the alleles of the genes that are changing in frequency. The random nature of genetic drift is a crucial point to understand: it specifically occurs when none of the variant alleles confer an advantage.<\/p>\n<figure style=\"width: 368px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image7-2.png\" alt=\"A smooth cell has a gently curving exterior surface, and a ruffled cell has undulating surface.\" width=\"368\" height=\"215\" \/><figcaption class=\"wp-caption-text\">Figure 5.7: Smooth and ruffled amoeba-like cells. Credit: Smooth and ruffled amoeba-like cells original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Andrea J. Alveshere is a collective work under a <a class=\"rId41\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\" target=\"_blank\">CC BY-NC-SA 4.0 License<\/a>. [Includes <a class=\"rId42\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Amoeba_proteus_TK-UT.svg\" target=\"_blank\">Amoeba Proteus TK-UT<\/a> by <a class=\"rId43\" href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Nefronus\" target=\"_blank\">Tom\u00e1\u0161 Kebert<\/a> and <a class=\"rId44\" href=\"https:\/\/www.umimeto.org\/\" target=\"_blank\">umimeto.org<\/a> (modified), <a class=\"rId45\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/deed.en\" target=\"_blank\">CC BY-SA 4.0<\/a>.]<\/figcaption><\/figure>\n<p class=\"import-Normal\">Let\u2019s imagine far back in time, again, to that ancient population of amoeba-like cells, subsisting and occasionally dividing, in the primordial sea. A mutation occurs in one of the cells that changes the texture of the cell membrane from a relatively smooth surface to a highly ruffled one (Figure 5.7). This has absolutely no effect on the cell\u2019s quality of life or ability to reproduce. In fact, eyes haven\u2019t evolved yet, so no one in the world at the time would even notice the difference. The cells in the population continue to divide, and the offspring of the ruffled cell inherit the ruffled membrane. The frequency (percentage) of the ruffled allele in the population, from one generation to the next, will depend entirely on how many offspring that first ruffled cell ends up having, and the random events that might make the ruffled alleles more common or more rare (such as population bottlenecks and founder effects, which are discussed below).<\/p>\n<h4 class=\"import-Normal\"><em>Sexual Reproduction and Random Inheritance<\/em><\/h4>\n<p class=\"import-Normal\">Tracking alleles gets a bit more complicated in our primordial cells when, after a number of generations, a series of mutations have created populations that reproduce sexually. These cells now must go through an extra round of cell division (meiosis) to create haploid gametes. The combination of two gametes is now required to produce each new diploid offspring.<\/p>\n<figure style=\"width: 262px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image8-1.png\" alt=\"A Punnett square with ruffled and smooth cells.\" width=\"262\" height=\"262\" \/><figcaption class=\"wp-caption-text\">Figure 5.8: A Punnett square demonstrating the sexual inheritance pattern of ruffled (dominant) and smooth amoeba-like primordial cells. Credit: Punnett square of primordial cells original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Andrea J. Alveshere is a collective work under a <a class=\"rId47\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\" target=\"_blank\">CC BY-NC-SA 4.0 License<\/a>. [Includes <a class=\"rId48\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Amoeba_proteus_TK-UT.svg\" target=\"_blank\">Amoeba Proteus TK-UT<\/a> by <a class=\"rId49\" href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Nefronus\" target=\"_blank\">Tom\u00e1\u0161 Kebert<\/a> and <a class=\"rId50\" href=\"https:\/\/www.umimeto.org\/\" target=\"_blank\">umimeto.org<\/a> (modified), <a class=\"rId51\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/deed.en\" target=\"_blank\">CC BY-SA 4.0<\/a>; <a class=\"rId52\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Punnett_hetero_x_hetero.svg\" target=\"_blank\">Punnett Hetero x Hetero<\/a> by <a class=\"rId53\" href=\"https:\/\/commons.wikimedia.org\/w\/index.php?title=User:Purpy_Pupple&amp;redirect=no\" target=\"_blank\">Purpy Pupple<\/a> (modified), <a class=\"rId54\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/deed.en\" target=\"_blank\">CC BY-SA 3.0<\/a>].<\/figcaption><\/figure>\n<p class=\"import-Normal\">In the earlier population, which reproduced via <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1534\">asexual reproduction<\/a><\/strong>, a cell either carried the smooth allele or the ruffled allele. With <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1536\">sexual reproduction<\/a><\/strong>, a cell inherits one allele from each parent, so there are homozygous cells that contain two smooth alleles, homozygous cells that contain two ruffled alleles, and heterozygous cells that contain one of each allele (Figure 5.8). If the new, ruffled allele happens to be dominant (and we\u2019ll imagine that it is), the heterozygotes will have ruffled cell <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1238\"><strong>phenotypes<\/strong><\/a> but also will have a 50\/50 chance of passing on a smooth allele to each offspring. As long as neither phenotype (ruffled nor smooth) provides any advantage over the other, the variation in the population from one generation to the next will remain completely random.<\/p>\n<p class=\"import-Normal\">In sexually reproducing populations (including humans and many other animals and plants in the world today), that 50\/50 chance of inheriting one or the other allele from each parent plays a major role in the random nature of genetic drift.<\/p>\n<h4 class=\"import-Normal\"><em>Population Bottlenecks <\/em><\/h4>\n<p class=\"import-Normal\">A <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1538\"><strong>population bottleneck<\/strong><\/a> occurs when the number of individuals in a population drops dramatically due to some random event. The most obvious, familiar examples are natural disasters. Tsunamis and hurricanes devastating island and coastal populations and forest fires and river floods wiping out populations in other areas are all too familiar. When a large portion of a population is randomly wiped out, the allele frequencies (i.e., the percentages of each allele) in the small population of survivors are often much different from the frequencies in the predisaster, or \u201cparent,\u201d population.<\/p>\n<p class=\"import-Normal\">If such an event happened to our primordial ocean cell population\u2014perhaps a volcanic fissure erupted in the ocean floor and only the cells that happened to be farthest from the spewing lava and boiling water survived\u2014we might end up, by random chance, with a surviving population that had mostly ruffled alleles, in contrast to the parent population, which had only a small percentage of ruffles (Figure 5.9).<\/p>\n<figure style=\"width: 665px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image9-2.png\" alt=\"Ruffled and smooth cells experience population bottleneck when a lava flow divides the populations.\" width=\"665\" height=\"332\" \/><figcaption class=\"wp-caption-text\">Figure 5.9: Illustration of a population of amoeba-like cells shifting from primarily smooth phenotypes (at left) to mostly ruffled phenotypes due to eruption of a volcanic fissure (at right) that exterminated the nearest cells. Credit: Population of amoeba-like cells and volcanic fissure original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Andrea J. Alveshere is a collective work under a <a class=\"rId56\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\" target=\"_blank\">CC BY-NC-SA 4.0 License<\/a>. [Includes <a class=\"rId57\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Amoeba_proteus_TK-UT.svg\" target=\"_blank\">Amoeba Proteus TK-UT<\/a> by <a class=\"rId58\" href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Nefronus\" target=\"_blank\">Tom\u00e1\u0161 Kebert<\/a> and <a class=\"rId59\" href=\"https:\/\/www.umimeto.org\/\" target=\"_blank\">umimeto.org<\/a> (modified), <a class=\"rId60\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/deed.en\" target=\"_blank\">CC BY-SA 4.0<\/a>.]<\/figcaption><\/figure>\n<p class=\"import-Normal\">One of the most famous examples of a population bottleneck is the prehistoric disaster that led to the extinction of dinosaurs, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1540\"><strong>Cretaceous\u2013Paleogene <\/strong><strong>extinction<\/strong><\/a> event (often abbreviated K\u2013Pg; previously K-T). This occurred approximately 66 million years ago. Dinosaurs and all their neighbours were going about their ordinary routines when a massive asteroid zoomed in from space and crashed into what is now the Gulf of Mexico, creating an impact so enormous that populations within hundreds of miles of the crash site were likely immediately wiped out. The skies filled with dust and debris, causing temperatures to plummet worldwide. It\u2019s estimated that 75% of the world\u2019s species went extinct as a result of the impact and the deep freeze that followed (Jablonski and Chaloner 1994).<\/p>\n<figure style=\"width: 399px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image10-2.png\" alt=\" A rat-like creature sits atop a dinosaur, raising a fist in a victorious gesture.\" width=\"399\" height=\"323\" \/><figcaption class=\"wp-caption-text\">Figure 5.10: The Cretaceous\u2013Paleogene extinction event, which led to the fall of the dinosaurs and rise of the mammals. Credit: <a class=\"rId62\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-3\/\" target=\"_blank\">The<\/a> <a class=\"rId64\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-3\/\" target=\"_blank\">Cretaceous\u2013Paleogene extinction event (Figure 4.12)<\/a> original to <a class=\"rId65\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a class=\"rId66\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">The populations that emerged from the K-Pg extinction were markedly different from their pre-disaster communities. Surviving mammal populations expanded and diversified, and other new creatures appeared. The ecosystems of Earth were filled with new organisms and have never been the same (Figure 5.10).<\/p>\n<p class=\"import-Normal\">Much more recently in geological time, during the colonial period, many human populations experienced bottlenecks as a result of the fact that imperial powers were inclined to slaughter communities who were reluctant to give up their lands and resources. This effect was especially profound in the Americas, where Indigenous populations faced the compounded effects of brutal warfare, exposure to new bacteria and viruses (against which they had no immunity), and ultimately segregation on resource-starved reservations. The populations in Europe, Asia, and Africa had experienced regular gene flow during the 10,000-year period in which most kinds of livestock were being domesticated, giving them many generations of experience building up immunity against zoonotic diseases (those that can pass from animals to humans). In contrast, the residents of the Americas had been almost completely isolated during those millennia, so all these diseases swept through the Americas in rapid succession, creating a major loss of genetic diversity in the Indigenous American population. It is estimated that between 50% and 95% of the Indigenous American populations died during the first decades after European contact, around 500 years ago (Livi-Bacci 2006).<\/p>\n<p class=\"import-Normal\">An urgent health challenge facing humans today involves human-induced population bottlenecks that produce antibiotic-resistant bacteria. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1451\"><strong>Antibiotics<\/strong> <\/a>are medicines prescribed to treat bacterial infections. The typical prescription includes enough medicine for ten days. People often feel better much sooner than ten days and sometimes decide to quit taking the medicine ahead of schedule. This is often a big mistake. The antibiotics have quickly killed off a large percentage of the bacteria\u2014enough to reduce the symptoms and make you feel much better. However, this has created a bacterial population bottleneck. There are usually a small number of bacteria that survive those early days. If you take the medicine as prescribed for the full ten days, it\u2019s quite likely that there will be no bacterial survivors. If you quit early, though, the survivors\u2014who were the members of the original population who were most resistant to the antibiotic\u2014will begin to reproduce again. Soon the infection will be back, possibly worse than before, and now all of the bacteria are resistant to the antibiotic that you had been prescribed.<\/p>\n<p class=\"import-Normal\">Other activities that have contributed to the rise of antibiotic-resistant bacteria include the use of antibacterial cleaning products and the inappropriate use of antibiotics as a preventative measure in livestock or to treat infections that are viral instead of bacterial (viruses do not respond to antibiotics). In 2017, the World Health Organization published a list of twelve antibiotic-resistant pathogens that are considered top priority targets for the development of new antibiotics (World Health Organization 2017).<\/p>\n<div class=\"textbox shaded\" style=\"background: var(--lightblue)\">\n<h2>Dig Deeper: The North American Elephant Seal: Thriving Bottleneck Populations That Still Face Genetic Defects<\/h2>\n<p>In 1892, the Northern Elephant Seal underwent a severe population bottleneck caused by commercial hunting, reducing the species to an estimated 20 individuals at the time. This drastic decline led to a substantial loss of genetic diversity\u2013a common consequence of extreme population bottlenecks (Hoelzel Et al., 2024 &amp; Weber Et al., 2000). While the population has since recovered to over 200,000 individuals, its genetic variability remains significantly low. Analyses of genetic markers, including allozymes, mitochondrial DNA, and microsatellites, consistently reflect this reduced diversity (Hoelzel Et al., 2024). Comparative studies further underscore this loss by highlighting the higher genetic variation observed in the Southern Elephant Seal, which did not experience similar population constraints (2024).<\/p>\n<figure style=\"width: 386px\" class=\"wp-caption alignleft\"><img src=\"https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/4\/48\/Elephant_seals_at_Ano_Nuevo_%2891577%29.jpg\/250px-Elephant_seals_at_Ano_Nuevo_%2891577%29.jpg\" alt=\"File:Elephant seals at Ano Nuevo (91577).jpg\" width=\"386\" height=\"295\" \/><figcaption class=\"wp-caption-text\">Figure 5.11 A male northern elephant seal (Mirounga angustirostris) with two pups at Ano Nuevo State Park. Credit: Elephant seals at Ano Nuevo by Rhododendrites is under <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\" target=\"_blank\" rel=\"noopener\">Creative Commons Attribution-Share Alike 4.0<\/a>.<\/figcaption><\/figure>\n<p>In a 2024 study for Nature, Ecology, and Evolution, Hoelzel and colleagues sequenced 260 modern and 8 historical genomes of the northern elephant seal. This comparison revealed a decrease in average heterozygosity from 0.00142 before the bottleneck to 0.000176 in the contemporary population, confirming the decline in genetic variation (2024). Hoelzel\u2019s mitogenome tree further illustrates this loss, revealing only two significant lineages remaining post-bottleneck, with limited diversity within each. Among the issues of diversity, the population has shown an increased number of loss-of-function (LOF) alleles, suggesting that increased inbreeding has amplified the frequency of these detrimental alleles; this reduced genetic diversity negatively affects both male and female reproductive fitness. Females who practiced repetitive inbreeding had higher LOF alleles and subsequently weaned fewer pups per year over their lifetime, while male reproductive success was linked to specific LOF loci associated with sperm production (2024). Hoelzel uses the example of \u201cAlpha-Male M12\u201d\u2013known for low paternity success despite frequent copulations\u2013which was homozygous for non-functional versions of four out of five LOF loci related to sperm function (2024, p. 688). The species' mating system, characterized by extreme polygyny, further exacerbates the loss of genetic variation even with countless copulatory partners<\/p>\n<p>Prior research published in Current Biology presents an empirical genetic assessment of this population bottleneck, highlighting its long-term genetic consequences, particularly the loss of mitochondrial diversity (Weber et al., 2000). In this research, Weber and colleagues note that random lineage sampling during the bottleneck led to the persistence of specific genetic variants by chance rather than through natural selection (2000). This research emphasizes that the loss of diversity poses potential future genetic vulnerabilities for the seals, and that further studies are crucial for understanding the full scope of these impacts on the seals' overall fitness (2000). In 2024, the work led by Hoelzen and company provided the missing data that the previous study had left unanswered. Their previously explored findings indicate that, although the seals have recovered in numbers, their genetic resilience remains compromised, leaving the population more vulnerable to future environmental pressures, such as climate change or resource shortages (Hoelzel Et al., 2024). Ultimately, while the population's size remains stable, the genetic consequences of the bottleneck indicate that past stochastic events continue to influence the seals' long-term fitness and adaptability.<\/p>\n<p>This research indicates that the historical bottleneck continues to affect the seals' health and fitness, despite the population's recovery. Limited genetic diversity and the persistence of harmful alleles due to inbreeding have continued to handicap the species' ability to thrive in environmental challenges such as climate change and resource fluctuations (2024). This emphasizes the importance of incorporating genetic factors into conservation strategies, as populations that have rebounded may still harbour long-term genetic weaknesses. Moreover, the elephant seal\u2019s history serves as a powerful example of how human actions \u2014such as overhunting \u2014 can have long-lasting impacts on biodiversity, reinforcing the importance of understanding human-environment interactions in ecological and conservation contexts.<\/p>\n<\/div>\n<h4 class=\"import-Normal\"><em>Founder Effects<\/em><\/h4>\n<p class=\"import-Normal\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1452\"><strong>Founder effects<\/strong><\/a> occur when members of a population leave the main or \u201cparent\u201d group and form a new population that no longer interbreeds with the other members of the original group. Similar to survivors of a population bottleneck, the newly founded population often has allele frequencies that are different from the original group. Alleles that may have been relatively rare in the parent population can end up being very common due to the founder effect. Likewise, recessive traits that were seldom seen in the parent population may be seen frequently in the descendants of the offshoot population.<\/p>\n<p class=\"import-Normal\">One striking example of the founder effect was first noted in the Dominican Republic in the 1970s. During a several-year period, eighteen children who had been born with female genitalia and raised as girls suddenly grew penises at puberty. This culture tended to value sons over daughters, so these transitions were generally celebrated. They labeled the condition <em><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1453\">guevedoces<\/a><\/strong><\/em>, which translates to \u201cpenis at twelve,\u201d due to the average age at which this occurred. Scientists were fascinated by the phenomenon.<\/p>\n<p class=\"import-Normal\">Genetic and hormonal studies revealed that the condition, scientifically termed <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1454\">5-alpha reductase deficiency<\/a>,<\/strong> is an autosomal recessive syndrome that manifests when a child having both X and Y sex chromosomes inherits two nonfunctional (mutated) copies of the <em>SRD5A2 <\/em>gene (Imperato-McGinley &amp; Zhu 2002). These children develop testes internally, but the 5-alpha reductase 2 steroid, which is necessary for development of male genitals in babies, is not produced. In absence of this male hormone, the baby develops female-looking genitalia (in humans, \u201cfemale\u201d is the default infant body form, if the full set of the necessary male hormones are not produced). At puberty, however, a different set of male hormones are produced by other fully functional genes. These hormones complete the male genital development that did not happen in infancy. This condition became quite common in the Dominican Republic during the 1970s due to founder effect\u2014that is, the mutated <em>SRD5A2<\/em> gene happened to be much more common among the Dominican Republic\u2019s founding population than in the parent populations. (The Dominican population derives from a mixture of Indigenous Americans [Taino] peoples, West Africans, and Western Europeans.) Five-alpha reductase syndrome has since been observed in other small, isolated populations around the world.<\/p>\n<p class=\"import-Normal\">Founder effect is closely linked to the concept of inbreeding, which in population genetics does not necessarily mean breeding with immediate family relatives. Instead, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1455\"><strong>inbreeding<\/strong> <\/a> refers to the selection of mates exclusively from within a small, closed population\u2014that is, from a group with limited allelic variability. This can be observed in small, physically isolated populations but also can happen when cultural practices limit mates to a small group. As with the founder effect, inbreeding increases the risk of inheriting two copies of any nonfunctional (mutant) alleles.<\/p>\n<p class=\"import-Normal\">The Amish in the United States are a population that, due to their unique history and cultural practices, emerged from a small founding population and have tended to select mates from within their groups. The <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1456\">Old Order Amish<\/a><\/strong> population of Lancaster County, Pennsylvania, has approximately 50,000 current members, all of whom can trace their ancestry back to a group of approximately 80 individuals. This small founding population immigrated to the United States from Switzerland in the mid-1700s to escape religious persecution. Since the Amish keep to themselves and almost exclusively select mates from within their own communities, they have more recessive traits compared to their parent population.<\/p>\n<figure style=\"width: 441px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image11-1.jpg\" alt=\"One individual\u2019s hands with six fingers.\" width=\"441\" height=\"331\" \/><figcaption class=\"wp-caption-text\">Figure 5.12: A person displaying polydactyly. Credit: <a class=\"rId68\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:6_Finger.JPG\" target=\"_blank\">6 Finger<\/a> by Wilhelmy is under a <a class=\"rId69\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\" target=\"_blank\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">One of the genetic conditions that has been observed much more frequently in the Lancaster County Amish population is <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1457\">Ellis-van Creveld syndrome<\/a><\/strong>, which is an autosomal recessive disorder characterized by short stature (dwarfism), polydactyly (the development of more than five digits [fingers or toes] on the hands or feet], abnormal tooth development, and heart defects (Figure 5.12). Among the general world population, Ellis-van Creveld syndrome is estimated to affect approximately 1 in 60,000 individuals; among the Old Order Amish of Lancaster County, the rate is estimated to be as high as 1 in every 200 births (D\u2019Asdia Et al. 2013).<\/p>\n<p class=\"import-Normal\">One important insight that has come from the study of founder effects is that a limited gene pool carries a much higher risk for genetic diseases. Genetic diversity in a population greatly reduces these risks.<\/p>\n<h3 class=\"import-Normal\"><strong>Gene Flow<\/strong><\/h3>\n<p class=\"import-Normal\">The third force of evolution is traditionally called gene flow. As with genetic drift, this is a misnomer, because it refers to flowing alleles, not genes. (All members of the same species share the same genes; it is the alleles of those genes that may vary.) <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1459\"><strong>Gene <\/strong><strong>f<\/strong><strong>low<\/strong> <\/a> refers to the movement of alleles from one population to another. In most cases, gene flow can be considered synonymous with migration.<\/p>\n<p class=\"import-Normal\">Returning again to the example of our primordial cell population, let\u2019s imagine that, after the volcanic fissure opened up in the ocean floor, wiping out the majority of the parent population, two surviving populations developed in the waters on opposite sides of the fissure. Ultimately, the lava from the fissure cooled into a large island that continued to provide a physical barrier between the populations (Figure 5.13).<\/p>\n<figure style=\"width: 685px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image12-2.png\" alt=\"An illustration of gene flow.\" width=\"685\" height=\"342\" \/><figcaption class=\"wp-caption-text\">Figure 5.13: Smooth and predominantly ruffled amoeba-like populations separated by a volcanic eruption (at left) and an island (at right) with unidirectional gene flow moving from east to west with ocean currents. Credit: Population of amoeba-like cells separated by volcanic eruption original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Andrea J. Alveshere is a collective work under a <a class=\"rId74\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\" target=\"_blank\">CC BY-NC-SA 4.0 License<\/a>. [Includes <a class=\"rId75\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Amoeba_proteus_TK-UT.svg\" target=\"_blank\">Amoeba Proteus TK-UT<\/a> by <a class=\"rId76\" href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Nefronus\" target=\"_blank\">Tom\u00e1\u0161 Kebert<\/a> and <a class=\"rId77\" href=\"https:\/\/www.umimeto.org\/\" target=\"_blank\">umimeto.org<\/a> (modified), <a class=\"rId78\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/deed.en\" target=\"_blank\">CC BY-SA 4.0<\/a>.]<\/figcaption><\/figure>\n<p class=\"import-Normal\">In the initial generations after the eruption, due to founder effect, isolation, and random inheritance (genetic drift), the population to the west of the islands contained a vast majority of the ruffled membrane alleles while the eastern population carried only the smooth alleles. Ocean currents in the area typically flowed from east to west, sometimes carrying cells (facilitating gene flow) from the eastern (smooth) population to the western (ruffled) population. Due to the ocean currents, it was almost impossible for any cells from the western population to be carried eastward. Thus, for inheritance purposes, the eastern (smooth) population remained isolated. In this case, the gene flow is unidirectional (going only in one direction) and unbalanced (only one population is receiving the new alleles).<\/p>\n<p class=\"import-Normal\">Among humans, gene flow is often described as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1460\"><strong>admixture<\/strong>.<\/a> In forensic cases, anthropologists and geneticists are often asked to estimate the ancestry of unidentified human remains to help determine whether they match any missing persons\u2019 reports. This is one of the most complicated tasks in these professions because, while \u201crace\u201d or \u201cancestry\u201d involves simple checkboxes on a missing person\u2019s form, among humans today there are no truly distinct genetic populations. All modern humans are members of the same fully breeding compatible species, and all human communities have experienced multiple episodes of gene flow (admixture), leading all humans today to be so genetically similar that we are all members of the same (and only surviving) human subspecies: <em>Homo sapiens sapiens.<\/em><\/p>\n<p class=\"import-Normal\">Gene flow between otherwise isolated nonhuman populations is often termed <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1461\">hybridization.<\/a>.<\/strong> One example of this involves the hybridization and spread of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1462\"><strong>Scutellata<\/strong><strong> honey bees<\/strong><\/a> (a.k.a. \u201ckiller bees\u201d) in the Americas. All honey bees worldwide are classified as <em>Apis mellifera.<\/em> Due to distinct adaptations to various environments around the world, there are 28 different subspecies of <em>Apis mellifera<\/em>.<\/p>\n<p class=\"import-Normal\">During the 1950s, a Brazilian biologist named Warwick E. Kerr experimented with hybridizing African and European subspecies of honey bees to try to develop a strain that was better suited to tropical environments than the European honey bees that had long been kept by North American beekeepers. Dr. Kerr was careful to contain the reproductive queens and drones from the African subspecies, but in 1957, a visiting beekeeper accidentally released 26 queen bees of the Scutellata subspecies (<em>Apis mellifera scutellata<\/em>) from southern Africa into the Brazilian countryside. The Scutellata bees quickly interbred with local European honey bee populations. The hybridized bees exhibited a much more aggressively defensive behaviour, fatally or near-fatally attacking many humans and livestock that ventured too close to their hives. The hybridized bees spread throughout South America and reached Mexico and California by 1985. By 1990, permanent colonies had been established in Texas, and by 1997, 90% of trapped bee swarms around Tucson, Arizona, were found to be Scutellata hybrids (Sanford 2006).<\/p>\n<p class=\"import-Normal\">Another example involves the introduction of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1463\"><strong>Harlequin ladybeetle<\/strong><\/a>, <em>Harmonia axyridis<\/em>, native to East Asia, to other parts of the world as a \u201cnatural\u201d form of pest control. Harlequin ladybeetles are natural predators of some of the aphids and other crop-pest insects. First introduced to North America in 1916, the \u201cbiocontrol\u201d strains of Harlequin ladybeetles were considered to be quite successful in reducing crop pests and saving farmers substantial amounts of money. After many decades of successful use in North America, biocontrol strains of Harlequin ladybeetles were also developed in Europe and South America in the 1980s.<\/p>\n<p class=\"import-Normal\">Over the seven decades of biocontrol use, the Harlequin ladybeetle had never shown any potential for development of wild colonies outside of its native habitat in China and Japan. New generations of beetles always had to be reared in the lab. That all changed in 1988, when a wild colony took root near New Orleans, Louisiana. Either through admixture with a native ladybeetle strain, or due to a spontaneous mutation, a new allele was clearly introduced into this population that suddenly enabled them to survive and reproduce in a wide range of environments. This population spread rapidly across the Americas and had reached Africa by 2004.<\/p>\n<p class=\"import-Normal\">In Europe, the invasive, North American strain of Harlequin ladybeetle admixed with the European strain (Figure 5.14), causing a population explosion (Lombaert Et al. 2010). Even strains specifically developed to be flightless (to curtail the spreading) produced flighted offspring after admixture with members of the North American population (Facon Et al. 2011). The fast-spreading, invasive strain has quickly become a disaster, out-competing native ladybeetle populations (some to the point of extinction), causing home infestations, decimating fruit crops, and contaminating many batches of wine with their bitter flavour after being inadvertently harvested with the grapes (Pickering Et al. 2004).<\/p>\n<figure style=\"width: 583px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image13-2.png\" alt=\"One gray ladybug is migrating to the group of white ladybugs.\" width=\"583\" height=\"219\" \/><figcaption class=\"wp-caption-text\">Figure 5.14: Gene flow between two populations of ladybeetles (ladybugs). Credit: <a class=\"rId80\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-3\/\" target=\"_blank\">Ladybug Gene Flow (Figure 4.14)<\/a> original to <a class=\"rId81\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a class=\"rId82\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<h3 class=\"import-Normal\"><strong>Natural Selection<\/strong><\/h3>\n<p class=\"import-Normal\">The final force of evolution is natural selection. This is the evolutionary process that Charles Darwin first brought to light, and it is what the general public typically evokes when considering the process of evolution. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1465\"><strong>Natural <\/strong><strong>s<\/strong><strong>election<\/strong><\/a> occurs when certain phenotypes confer an advantage or disadvantage in survival and\/or reproductive success. The alleles associated with those phenotypes will change in frequency over time due to this selective pressure. It\u2019s also important to note that the advantageous allele may change over time (with environmental changes) and that an allele that had previously been benign may become advantageous or detrimental. Of course, dominant, recessive, and codominant traits will be selected upon a bit differently from one another. Because natural selection acts on phenotypes rather than the alleles themselves, deleterious (disadvantageous) alleles can be retained by heterozygotes without any negative effects.<\/p>\n<p class=\"import-Normal\">In the case of our primordial ocean cells, up until now, the texture of their cell membranes has been benign. The frequencies of smooth to ruffled alleles, and smooth to ruffled phenotypes, has changed over time, due to genetic drift and gene flow. Let\u2019s now imagine that the Earth\u2019s climate has cooled to a point that the waters frequently become too cold for survival of the tiny bacteria that are the dietary staples of our smooth and ruffled cell populations. The way amoeba-like cells \u201ceat\u201d is to stretch out the cell membrane, almost like an arm, to encapsulate, then ingest, the tiny bacteria. When the temperatures plummet, the tiny bacteria populations plummet with them. Larger bacteria, however, are better able to withstand the temperature change.<\/p>\n<p class=\"import-Normal\">The smooth cells were well-adapted to ingesting tiny bacteria but poorly suited to encapsulating the larger bacteria. The cells with the ruffled membranes, however, are easily able to extend their ruffles to encapsulate the larger bacteria. They also find themselves able to stretch their entire membrane to a much larger size than their smooth-surfaced neighbours, allowing them to ingest more bacteria at a given time and to go for longer periods between feedings (Figure 5.15).<\/p>\n<figure style=\"width: 528px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image14-2.png\" alt=\"Smooth and ruffled cells feeding on large and small bacteria.\" width=\"528\" height=\"307\" \/><figcaption class=\"wp-caption-text\">Figure 5.15: Smooth and ruffled cells feeding. Credit: Smooth and ruffled cells feeding original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Andrea J. Alveshere is a collective work under a <a class=\"rId84\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\" target=\"_blank\">CC BY-NC-SA 4.0 License<\/a>. [Includes <a class=\"rId85\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Cladograma_dos_Dom%C3%ADnios_e_Reinos.png\" target=\"_blank\">Cladograma dos Dominios e Reinos<\/a> by <a class=\"rId86\" href=\"https:\/\/commons.wikimedia.org\/wiki\/User:MarceloTeles\" target=\"_blank\">MarceloTeles<\/a> (modified), <a class=\"rId87\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/deed.en\" target=\"_blank\">CC BY-SA 4.0<\/a><a class=\"rId88\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/deed.en\" target=\"_blank\">; <\/a><a class=\"rId89\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Amoeba_proteus_TK-UT.svg\" target=\"_blank\">Amoeba Proteus TK-UT<\/a> by <a class=\"rId90\" href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Nefronus\" target=\"_blank\">Tom\u00e1\u0161 Kebert<\/a> and <a class=\"rId91\" href=\"https:\/\/www.umimeto.org\/\" target=\"_blank\">umimeto.org<\/a> (modified), <a class=\"rId92\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/deed.en\" target=\"_blank\">CC BY-SA 4.0<\/a>.]<\/figcaption><\/figure>\n<p class=\"import-Normal\">The smooth and ruffled traits, which had previously offered no advantage or disadvantage while food was plentiful, now are subject to natural selection. During the cold snaps, at least, the ruffled cells have a definite advantage. We can imagine that the western population that has mostly ruffled alleles will continue to do well, while the eastern population is at risk of dying out if the smaller bacteria remain scarce and no ruffled alleles are introduced.<\/p>\n<p class=\"import-Normal\">A classic example of natural selection involves the study of an insect called the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1466\">peppered moth<\/a><\/strong> (<em>Biston betularia<\/em>) in England during the Industrial Revolution in the 1800s. Prior to the Industrial Revolution, the peppered moth population was predominantly light in colour, with dark (pepper-like) speckles on the wings. The \u201cpeppered\u201d colouration was very similar to the appearance of the bark and lichens that grew on the local trees (Figure 5.16). This helped to camouflage the moths as they rested on a tree, making it harder for moth-eating birds to find and snack on them. There was another phenotype that popped up occasionally in the population. These individuals were heterozygotes that carried an overactive, dominant pigment allele, producing a solid black colouration. As you can imagine, the black moths were much easier for birds to spot, making this phenotype a real disadvantage.<\/p>\n<p class=\"import-Normal\">The situation changed, however, as the Industrial Revolution took off. Large factories began spewing vast amounts of coal smoke into the air, blanketing the countryside, including the lichens and trees, in black soot. Suddenly, it was the light-coloured moths that were easy for birds to spot and the black moths that held the advantage. The frequency of the dark pigment allele rose dramatically. By 1895, the black moth phenotype accounted for 98% of observed moths (Grant 1999).<\/p>\n<figure style=\"width: 476px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image15-2.png\" alt=\"An illustration of natural selection.\" width=\"476\" height=\"531\" \/><figcaption class=\"wp-caption-text\">Figure 5.16: Dark and light peppered moth variants and their relative camouflage abilities on clean (top) and sooty (bottom) trees. Credit: <a class=\"rId94\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Peppered_moths_c2.jpg\" target=\"_blank\">Peppered moths c2<\/a> by Khaydock is under a <a class=\"rId95\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Thanks to new environmental regulations in the 1960s, the air pollution in England began to taper off. As the soot levels decreased, returning the trees to their former, lighter colour, this provided the perfect opportunity to study how the peppered moth population would respond. Repeated follow-up studies documented the gradual rise in the frequency of the lighter-coloured phenotype. By 2003, the maximum frequency of the dark phenotype was 50% and in most parts of England had decreased to less than 10% (Cook, 2003).<\/p>\n<h4 class=\"import-Normal\"><em>Directional, Balancing\/Stabilizing, and Disruptive\/Diversifying Selection<\/em><\/h4>\n<p class=\"import-Normal\">Natural selection can be classified as directional, balancing\/stabilizing, or disruptive\/diversifying, depending on how the pressure is applied to the population (Figure 5.17).<\/p>\n<figure style=\"width: 465px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image16-2.png\" alt=\"Three types of selection; balancing, directional and disruptive\/diversifying\" width=\"465\" height=\"574\" \/><figcaption class=\"wp-caption-text\">Figure 5.17: Lines depict the affects of (a) Balancing\/Stabilizing, (b) Directional, and (c) Disruptive\/Diversifying selection on populations. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available<\/a>. Credit: <a class=\"rId97\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Figure_19_03_01.png\" target=\"_blank\">Biology (ID: 185cbf87-c72e-48f5-b51e-f14f21b5eabd@9.17)<\/a> by <a class=\"rId98\" href=\"https:\/\/cnx.org\/\" target=\"_blank\">CNX OpenStax<\/a> is used under a <a class=\"rId99\" href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/deed.en\" target=\"_blank\">CC BY 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Both of the above examples of natural selection involve <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1467\">directional selection<\/a><\/strong>: the environmental pressures favour one phenotype over the other and cause the frequencies of the associated advantageous alleles (ruffled membranes, dark pigment) to gradually increase. In the case of the peppered moths, the direction shifted three times: first, it was selecting for lighter pigment; then, with the increase in pollution, the pressure switched to selection for darker pigment; finally, with reduction of the pollution, the selection pressure shifted back again to favouring light-coloured moths.<\/p>\n<p class=\"import-Normal\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1468\"><strong>Balancing selection<\/strong><\/a> (a.k.a. stabilizing selection) occurs when selection works against the extremes of a trait and favours the intermediate phenotype. For example, humans maintain an average birth weight that balances the need for babies to be small enough not to cause complications during pregnancy and childbirth but big enough to maintain a safe body temperature after they are born. Another example of balancing selection is found in the genetic disorder called sickle cell anemia (see \u201cSpecial Topic: Sickle Cell Anemia\u201d).<\/p>\n<p class=\"import-Normal\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1469\"><strong>Disruptive selection<\/strong><\/a> (a.k.a. diversifying selection), the opposite of balancing selection, occurs when both extremes of a trait are advantageous. Since individuals with traits in the mid-range are selected against, disruptive selection can eventually lead to the population evolving into two separate species. Darwin believed that the many species of finches (small birds) found in the remote Galapagos Islands provided a clear example of disruptive selection leading to speciation. He observed that seed-eating finches either had large beaks, capable of eating very large seeds, or small beaks, capable of retrieving tiny seeds. The islands did not have many plants that produced medium-size seeds. Thus, birds with medium-size beaks would have trouble eating the very large seeds and would also have been inefficient at picking up the tiny seeds. Over time, Darwin surmised, this pressure against mid-size beaks may have led the population to divide into two separate species.<\/p>\n<h4 class=\"import-Normal\"><em>Sexual Selection<\/em><\/h4>\n<p class=\"import-Normal\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1470\"><strong>Sexual <\/strong><strong>s<\/strong><strong>election<\/strong><\/a> is an aspect of natural selection in which the selective pressure specifically affects reproductive success (the ability to successfully breed and raise offspring) rather than survival. Sexual selection favours traits that will attract a mate. Sometimes these sexually appealing traits even carry greater risks in terms of survival.<\/p>\n<figure style=\"width: 354px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image17-2.png\" alt=\"A fox chases a peacock fleeing; a peacock displays his feathers to a peahen.\" width=\"354\" height=\"413\" \/><figcaption class=\"wp-caption-text\">Figure 5.18: Showy peacock tail disadvantages (becoming easier prey) and advantages (impressing peahens). Credit: <a class=\"rId101\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-3\/\" target=\"_blank\">Peacock tail advantage and disadvantages (Figure 4.18)<\/a> original to <a class=\"rId102\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a class=\"rId103\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.License.<\/figcaption><\/figure>\n<p class=\"import-Normal\">A classic example of sexual selection involves the brightly coloured feathers of the peacock. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1471\"><strong>peacock<\/strong><\/a> is the male sex of the peafowl genera <em>Pavo<\/em> and <em>Afropavo. <\/em>During mating season, peacocks will fan their colourful tails wide and strut in front of the peahens in a grand display. The peahens will carefully observe these displays and will elect to mate with the male that they find the most appealing. Many studies have found that peahens prefer the males with the fullest, most colourful tails. While these large, showy tails provide a reproductive advantage, they can be a real burden in terms of escaping predators. The bright colours and patterns as well as the large size of the peacock tail make it difficult to hide. Once predators spot them, peacocks also struggle to fly away, with the heavy tail trailing behind and weighing them down (Figure 5.18). Some researchers have argued that the increased risk is part of the appeal for the peahens: only an especially strong, alert, and healthy peacock would be able to avoid predators while sporting such a spectacular tail.<\/p>\n<p>&lt;!-- <\/p><\/div>\n<p> --&gt;<br \/>\nIt\u2019s important to keep in mind that sexual selection relies on the trait being present throughout mating years. Reflecting on the NF1 genetic disorder (see \u201cSpecial Topic: Neurofibromatosis Type 1 [NF1]\u201d), given how disfiguring the symptoms can become, some might find it surprising that half of the babies born with NF1 inherited it from a parent. Given that the disorder is autosomal dominant and fully penetrant (meaning it has no unaffected carriers), it may seem surprising that sexual selection doesn\u2019t exert more pressure against the mutated alleles. One important factor is that, while the neurofibromas typically begin to appear during puberty, they usually emerge only a few at a time and may grow very slowly. Many NF1 patients don\u2019t experience the more severe or disfiguring symptoms until later in life, long after they have started families of their own.<\/p>\n<p class=\"import-Normal\">Some researchers prefer to classify sexual selection separately, as a fifth force of evolution. The traits that underpin mate selection are entirely natural, of course. Research has shown that subtle traits, such as the type of pheromones (hormonal odors related to immune system alleles) someone emits and how those are perceived by the immune system genotype of the \u201csniffer,\u201d may play crucial and subconscious roles in whether we find someone attractive or not (Chaix, Cao, &amp; Donnelly 2008).<\/p>\n<div class=\"textbox\">\n<h2><\/h2>\n<h2 class=\"import-Normal\">Special Topic: Neurofibromatosis Type 1 (NF1)<\/h2>\n<p class=\"import-Normal\"><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1476\">Neurofibromatosis Type 1<\/a><\/strong>, also known as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1477\"><strong>NF1<\/strong><\/a>, is a genetic disorder that illustrates how a mutation in a single gene can affect multiple systems in the body. Surprisingly common, more people have NF1 than cystic fibrosis and muscular dystrophy combined. Even more surprising, given how common it is, is how few people have heard of it. One in every 3,000 babies is born with NF1, and this holds true for all populations worldwide (Riccardi 1992). This means that, for every 3,000 people in your community, there is likely at least one person living with this disorder. NF1 is an <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1478\">autosomal dominant<\/a> <\/strong>condition, which means that everyone born with a mutation in the gene, whether inherited or spontaneous, has a 50\/50 chance of passing it on to each of their own children.<\/p>\n<p class=\"import-Normal\">The NF1 disorder results from mutation of the <em>NF1<\/em> gene on Chromosome 17. Almost any mutation that affects the sequence of the gene\u2019s protein product, neurofibromin, will cause the disorder. Studies of individuals with NF1 have identified over 3,000 different mutations of all kinds (including point mutations, small and large indels, and translocations). The <em>NF1 <\/em>gene is one of the largest known genes, containing at least 60 <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_724\">exons<\/a><\/strong> (protein-encoding sequences) in a span of about 300,000 nucleotides.<\/p>\n<p class=\"import-Normal\">We know that neurofibromin plays an important role in preventing tumor growth because one of the most common symptoms of the NF1 disorder is the growth of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1479\">benign<\/a> <\/strong>(noncancerous) tumors, called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1486\">neurofibromas<\/a><\/strong>. Neurofibromas sprout from nerve sheaths\u2014the tissues that encase our nerves\u2014throughout the body, usually beginning around puberty. There is no way to predict where the tumors will occur, or when or how quickly they will grow, although only about 15% turn <strong>malignant<\/strong> (cancerous). The two types of neurofibromas that are typically most visible are <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1480\"><strong>cutaneous neurofibromas<\/strong><\/a>, which are spherical bumps on, or just under, the surface of the skin (Figure 5.19), and <strong>plexiform neurofibromas<\/strong><em>, <\/em>growths involving whole branches of nerves, often giving the appearance that the surface of the skin is \u201cmelting\u201d (Figure 5.20).<\/p>\n<figure id=\"attachment_131\" aria-describedby=\"caption-attachment-131\" style=\"width: 510px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-129\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/4.18.jpg\" alt=\"A woman has dozens of round, skin-colored tumors visible on her face, neck, and hand.\" width=\"510\" height=\"340\" \/><figcaption id=\"caption-attachment-131\" class=\"wp-caption-text\">Figure 5.19: A woman with many cutaneous neurofibromas, a common symptom of Neurofibromatosis Type 1. Credit: <a class=\"rId105\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-3\/\" target=\"_blank\">Woman with cutaneous neurofibromas (symptom of NF1)<\/a> by <a class=\"rId106\" href=\"https:\/\/positiveexposure.org\/about-the-program-2\/rick-guidotti\/\" target=\"_blank\">Rick Guidotti of Positive Exposure<\/a> is used with permission and is available here under a <a class=\"rId107\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<figure id=\"attachment_131-2\" aria-describedby=\"caption-attachment-131-2\" style=\"width: 1900px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-130 size-full\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/4.19.jpg\" alt=\"An adult with large plexiform neurofibromas covering his face, none are on the child.\" width=\"1900\" height=\"700\" \/><figcaption id=\"caption-attachment-131-2\" class=\"wp-caption-text\">Figure 5.20: Photo on the left is of a man with large plexiform neurofibroma, another symptom of Neurofibromatosis Type 1. Photo on the right is a childhood photo of the same man, illustrating the progressive nature of the NF1 disorder. Credit: <a class=\"rId110\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-3\/\" target=\"_blank\">Man with plexiform neurofibroma (symptom of NF1)<\/a> from Ashok Shrestha is used by permission and available here under a <a class=\"rId111\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>. <a class=\"rId112\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-3\/\" target=\"_blank\">Childhood photo of the same man with NF1 disorder<\/a> from Ashok Shrestha is used by permission and available here under a <a class=\"rId113\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Unfortunately, there is currently no cure for NF1. Surgical removal of neurofibromas risks paralysis, due to the high potential for nerve damage, and often results in the tumors growing back even more vigorously. This means that patients are often forced to live with disfiguring and often painful neurofibromas. People who are not familiar with NF1 often mistake neurofibromas for something contagious. This makes it especially hard for people living with NF1 to get jobs working with the public or even to enjoy spending time away from home. Raising public awareness about NF1 and its symptoms can be a great help in improving the quality of life for people living with this condition.<\/p>\n<figure style=\"width: 311px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image21-2.png\" alt=\"A child with darker oval birthmarks scattered across his torso and arms.\" width=\"311\" height=\"415\" \/><figcaption class=\"wp-caption-text\">Figure 5.21: Image of a child with caf\u00e9-au-lait macules (birthmarks) typical of the earliest symptoms of NF1. Credit: <a class=\"rId115\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-3\/\" target=\"_blank\">Child with caf\u00e9-au-lait macules (birthmarks) typical of the earliest symptoms of NF1<\/a> by Andrea J. Alveshere is under a <a class=\"rId116\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">One of the first symptoms of NF1 in a small child is usually the appearance of <strong>caf\u00e9-au-lait spots<\/strong>, or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1490\"><strong>CALS<\/strong><\/a>, which are flat, brown birthmark-like spots on the skin (Figure 5.21). CALS are often light brown, similar to the colour of coffee with cream, which is the reason for the name, although the shade of the pigment depends on a person\u2019s overall complexion. Some babies are born with CALS, but for others the spots appear within the first few years of life. Having six or more CALS larger than five millimetres (mm) across is a strong indicator that a child may have NF1.<\/p>\n<p class=\"import-Normal\">Other common symptoms include the following: gliomas (tumors) of the optic nerve, which can cause vision loss; thinning of bones and failure to heal if they break (often requiring amputation); low muscle tone (poor muscle development, often delaying milestones such as sitting up, crawling, and walking); hearing loss, due to neurofibromas on auditory nerves; and learning disabilities, especially those involving spatial reasoning. Approximately 50% of people with NF1 have some type of speech and\/or learning disability and often benefit greatly from early intervention services. Generalized developmental disability, however, is not common with NF1, so most people with NF1 live independently as adults. Many people with NF1 live full and successful lives, as long as their symptoms can be managed.<\/p>\n<p class=\"import-Normal\">Based on the wide variety of symptoms, it\u2019s clear that the neurofibromin protein plays important roles in many biochemical pathways. While everyone who has NF1 will exhibit some symptoms during their lifetime, there is a great deal of variation in the types and severity of symptoms, even between individuals from the same family who share the exact same NF1 mutation. It seems crazy that a gene with so many important functions would be so susceptible to mutation. Part of this undoubtedly has to do with its massive size\u2014a gene with 300,000 nucleotides has ten times more nucleotides available for mutation than does a gene of 30,000 bases. This also suggests that the mutability of this gene might provide some benefits, which is a possibility that we will revisit later in this chapter.<\/p>\n<\/div>\n<div class=\"textbox\">\n<h2 class=\"import-Normal\">Special Topic: Sickle Cell Anemia<\/h2>\n<p class=\"import-Normal\"><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1492\">Sickle cell anemia<\/a><\/strong> is an autosomal recessive genetic disorder that affects millions of people worldwide. It is most common in Africa, countries around the Mediterranean Sea, and eastward as far as India. Populations in the Americas that have high percentages of ancestors from these regions also have high rates of sickle cell anemia. In the United States, it\u2019s estimated that 72,000 people live with the disease, with one in approximately 1,200 Hispanic-American babies and one in every 500 African-American babies inheriting the condition (World Health Organization 1996).<\/p>\n<figure style=\"width: 344px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image22-2.png\" alt=\"Round and sickle cells.\" width=\"344\" height=\"258\" \/><figcaption class=\"wp-caption-text\">Figure 5.22: Sickle cell anemia. Arrows indicate (a) sickled and (b) normal red blood cells. Credit: <a class=\"rId118\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Sickle-cell_smear_2015-09-10.jpg\">Sickle-cell smear 2015-09-10<\/a> by Paulo Henrique Orlandi Mourao has been modified (contrast modified and labels added) and is under a <a class=\"rId119\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\" target=\"_blank\">CC BY-NC-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Sickle cell anemia affects the hemoglobin protein in red blood cells. Normal red blood cells are somewhat doughnut-shaped\u2014round with a depression on both sides of the middle. They carry oxygen around the bloodstream to cells throughout the body. Red blood cells produced by the mutated form of the gene take on a stiff, sickle-like crescent shape when stressed by low oxygen or dehydration (Figure 5.22). Because of their elongated shape and the fact that they are stiff rather than flexible, they tend to form clumps in the blood vessels, inhibiting blood flow to adjacent areas of the body. This causes episodes of extreme pain and can cause serious problems in the oxygen-deprived tissues. The sickle cells also break down much more quickly than normal cells, often lasting only 20 days rather than the 120 days of normal cells. This causes an overall shortage of blood cells in the sickle cell patient, resulting in low iron (anemia) and problems associated with it such as extreme fatigue, shortness of breath, and hindrances to children\u2019s growth and development.<\/p>\n<p class=\"import-Normal\">The devastating effects of sickle cell anemia made its high frequency a pressing mystery. Why would an allele that is so deleterious in its homozygous form be maintained in a population at levels as high as the one in twelve African Americans estimated to carry at least one copy of the allele? The answer turned out to be one of the most interesting cases of balancing selection in the history of genetic study.<\/p>\n<p class=\"import-Normal\">While looking for an explanation, scientists noticed that the countries with high rates of sickle cell disease also shared a high risk for another disease called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1493\"><strong>malaria<\/strong><\/a>, which is caused by infection of the blood by a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1494\"><strong><em>Plasmodium<\/em><\/strong><\/a> parasite. These parasites are carried by mosquitoes and enter the human bloodstream via a mosquito bite. Once infected, the person will experience flu-like symptoms that, if untreated, can often lead to death. Researchers discovered that many people living in these regions seemed to have a natural resistance to malaria. Further study revealed that people who carry the sickle cell allele are far less likely to experience a severe case of malaria. This would not be enough of a benefit to make the allele advantageous for the sickle cell homozygotes, who face shortened life spans due to sickle cell anemia. The real benefit of the sickle cell allele goes to the heterozygotes.<\/p>\n<p class=\"import-Normal\">People who are heterozygous for sickle cell carry one normal allele, which produces the normal, round, red blood cells, and one sickle cell allele, which produces the sickle-shaped red blood cells. Thus, they have both the sickle and round blood cell types in their bloodstream. They produce enough of the round red blood cells to avoid the symptoms of sickle cell anemia, but they have enough sickle cells to provide protection from malaria.<\/p>\n<p class=\"import-Normal\">When the <em>Plasmodium <\/em>parasites infect an individual, they begin to multiply in the liver, but then must infect the red blood cells to complete their reproductive cycle. When the parasites enter sickle-type cells, the cells respond by taking on the sickle shape. This prevents the parasite from circulating through the bloodstream and completing its life cycle, greatly inhibiting the severity of the infection in the sickle cell heterozygotes compared to non\u2013-sickle cell homozygotes. See Chapter 14 for more discussion of sickle cell anemia.<\/p>\n<\/div>\n<div class=\"textbox\">\n<h2 class=\"import-Normal\">Special Topic: The Real Primordial Cells\u2014<em>Dictyostelium Discoideum<\/em><\/h2>\n<p class=\"import-Normal\">The amoeba-like primordial cells that were used as recurring examples throughout this chapter are inspired by actual research that is truly fascinating. In 2015, Gareth Bloomfield and colleagues reported on their genomic study of the social amoeba <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1496\"><strong><em>Dictyostelium discoideum<\/em><\/strong> <\/a>(a.k.a. \u201cslime molds,\u201d although technically they are amoebae, not molds). Strains of these amoebae have been grown in research laboratories for many decades and are useful in studying the mechanisms that amoeboid single-celled organisms use to ingest food and liquid. For simplification of our examples in this chapter, our amoeba-like cells remained ocean dwellers. Wild <em>Dictyostelium discoideum<\/em>, however, live in soil and feed on soil bacteria by growing ruffles in their membranes that reach out to encapsulate the bacterial cell. Laboratory strains, however, are typically raised on liquid media (agar) in Petri dishes, which is not suitable for the wild-type amoebae. It was widely known that the laboratory strains must have developed mutations in one or more genes to allow them to ingest the larger nutrient particles in the agar and larger volumes of liquid, but the genes involved were not known.<\/p>\n<p class=\"import-Normal\">Bloomfield and colleagues performed genomic testing on both the wild and the laboratory strains of <em>Dictyostelium discoideum. <\/em>Their discovery was astounding: every one of the laboratory strains carried a mutation in the <em>NF1 <\/em>gene, the very same gene associated with Neurofibromatosis Type 1 (NF1) in humans. The antiquity of this massive, easily mutated gene is incredible. It originated in an ancestor common to both humans and these amoebae, and it has been retained in both lineages ever since. As seen in <em>Dictyostelium discoideum<\/em>, breaking the gene can be advantageous. Without a functioning copy of the neurofibromin protein, the cell membrane is able to form much-larger feeding structures, allowing the <em>NF1 <\/em>mutants to ingest larger particles and larger volumes of liquid. For these amoebae, this may provide dietary flexibility that functions somewhat like an insurance policy for times when the food supply is limited.<\/p>\n<p class=\"import-Normal\"><em>Dictyostelium discoideum <\/em>are also interesting in that they typically reproduce asexually, but under certain conditions, one cell will convert into a \u201cgiant\u201d cell, which encapsulates surrounding cells, transforming into one of three sexes. This cell will undergo meiosis, producing gametes that must combine with one of the other two sexes to produce viable offspring. This ability for sexual reproduction may be what allows <em>Dictyostelium discoideum<\/em> to benefit from the advantages of <em>NF1<\/em> mutation, while also being able to restore the wild type <em>NF1<\/em> gene in future generations.<\/p>\n<p class=\"import-Normal\">What does this mean for humans living with NF1? Well, understanding the role of the neurofibromin protein in the membranes of simple organisms like <em>Dictyostelium discoideum<\/em> may help us to better understand how it functions and malfunctions in the sheaths of human neurons. It\u2019s also possible that the mutability of the NF1 gene confers certain advantages to humans as well. Alleles of the NF1 gene have been found to reduce one\u2019s risk for alcoholism (Repunte-Canonigo Vez Et al. 2015), opiate addiction (Sanna Et al. 2002), Type 2 diabetes (Martins Et al. 2016), and hypomusicality (a lower-than-average musical aptitude; Cota Et al. 2018). This research is ongoing and will be exciting to follow in the coming years.<\/p>\n<\/div>\n<h2 class=\"__UNKNOWN__\">Studying Evolution in Action<\/h2>\n<div class=\"__UNKNOWN__\">\n<h3 class=\"import-Normal\"><strong>The Hardy-Weinberg Equilibrium <\/strong><\/h3>\n<p class=\"import-Normal\">This chapter has introduced you to the forces of evolution, the mechanisms by which evolution occurs. How do we detect and study evolution, though, in real time, as it happens? One tool we use is the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1497\"><strong>Hardy-<\/strong><strong>Weinberg<\/strong><strong> Equilibrium<\/strong><\/a>: a mathematical formula that allows estimation of the number and distribution of dominant and recessive alleles in a population. This aids in determining whether allele frequencies are changing and, if so, how quickly over time, and in favour of which allele? It\u2019s important to note that the Hardy-Weinberg formula only gives us an estimate based on the data for a snapshot in time. We will have to calculate it again later, after various intervals, to determine if our population is evolving and in what way the allele frequencies are changing.<\/p>\n<h3 class=\"import-Normal\">Calculating the Hardy-Weinberg Equilibrium<\/h3>\n<p class=\"import-Normal\">In the Hardy-Weinberg formula, <em>p <\/em>represents the frequency of the dominant allele, and <em>q<\/em> represents the frequency of the recessive allele. Remember, an allele\u2019s frequency is the proportion, or percentage, of that allele in the population. For the purposes of Hardy-Weinberg, we give the allele percentages as decimal numbers (e.g., 42% = 0.42), with the entire population (100% of alleles) equaling 1. If we can figure out the frequency of one of the alleles in the population, then it is simple to calculate the other. Simply subtract the known frequency from 1 (the entire population): 1<em> \u2013 p = q<\/em> and 1<em> \u2013 q = p<\/em>.<\/p>\n<p class=\"import-Normal\">The Hardy-Weinberg formula is <em>p<\/em><sup><em>2<\/em><\/sup><em> + 2pq + q<\/em><sup><em>2<\/em><\/sup>, where:<\/p>\n<p class=\"import-Normal\" style=\"padding-left: 40px\"><em>p<\/em><sup><em>2<\/em><\/sup> represents the frequency of the homozygous dominant genotype;<\/p>\n<p class=\"import-Normal\" style=\"padding-left: 40px\"><em>2pq<\/em> represents the frequency of the heterozygous genotype; and<\/p>\n<p class=\"import-Normal\" style=\"padding-left: 40px\"><em>q<\/em><sup><em>2<\/em><\/sup> represents the frequency of the homozygous recessive genotype.<\/p>\n<p class=\"import-Normal\">It is often easiest to determine <em>q<\/em><sup><em>2<\/em><\/sup> first, simply by counting the number of individuals with the unique, homozygous recessive phenotype (then dividing by the total individuals in the population to arrive at the \u201cfrequency\u201d). Once we have this number, we simply need to calculate the square root of the homozygous recessive phenotype frequency. That gives us <em>q.<\/em> Remember, 1 <em>\u2013<\/em> <em>q <\/em>equals <em>p<\/em>, so now we have the frequencies for both alleles in the population. If we needed to figure out the frequencies of heterozygotes and homozygous dominant genotypes, we\u2019d just need to plug the <em>p<\/em> and <em>q<\/em> frequencies back into the <em>p<\/em><sup><em>2<\/em><\/sup> and 2<em>pq<\/em> formulas.<\/p>\n<figure style=\"width: 329px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image25-1.png\" alt=\"A circle with seven grey and three white ladybugs.\" width=\"329\" height=\"347\" \/><figcaption class=\"wp-caption-text\">Figure 5.23: Ladybug population with a mixture of dark (red) and light (orange) individuals. Credit: <a class=\"rId129\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-3\/\" target=\"_blank\">Ladybug mix (Figure 4.21)<\/a> original to <a class=\"rId130\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a class=\"rId131\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Let\u2019s imagine we have a population of ladybeetles that carries two alleles: a dominant allele that produces red ladybeetles and a recessive allele that produces orange ladybeetles. Since red is dominant, we\u2019ll use <em>R <\/em>to represent the red allele, and <em>r <\/em>to represent the orange allele. Our population has ten beetles, and seven are red and three are orange (Figure 5.23). Let\u2019s calculate the number of genotypes and alleles in this population.<\/p>\n<p class=\"import-Normal\">Of ten total beetles, we have three orange beetles3\/10 = .30 (30%) frequency\u2014and we know they are homozygous recessive (<em>rr<\/em>). So:<\/p>\n<p class=\"import-Normal\" style=\"text-indent: 36pt\"><em>rr = .3; <\/em>therefore, <em>r = <\/em>\u221a.3 = .5477<\/p>\n<p class=\"import-Normal\" style=\"text-indent: 36pt\"><em>R<\/em> = 1 <em>\u2013<\/em> .5477 = .4523<\/p>\n<p class=\"import-Normal\" style=\"text-indent: 36pt\">Using the Hardy-Weinberg formula:<\/p>\n<p class=\"import-Normal\" style=\"text-indent: 36pt\">1=.4523<sup>2 <\/sup>+ 2 x .4523 x .5477 +.5477<sup>2 <\/sup>= .20 + .50 + .30 = 1<\/p>\n<p class=\"import-Normal\" style=\"text-indent: 36pt\">Thus, the genotype breakdown is 20% <em>RR, <\/em>50%<em> Rr, <\/em>and 30%<em> rr <\/em><\/p>\n<p class=\"import-Normal\" style=\"text-indent: 36pt\">(2 red homozygotes, 5 red heterozygotes, and 3 orange homozygotes).<\/p>\n<p class=\"import-Normal\">Since we have 10 individuals, we know we have 20 total alleles: 4 red from the <em>RR<\/em> group, 5 red and 5 orange from the <em>Rr<\/em> group, and 6 orange from the <em>rr<\/em> group, for a grand total of 9 red and 11 orange (45% red and 55% orange, just like we estimated in the 1 \u2013 <em>q <\/em>step).<\/p>\n<p class=\"import-Normal\">Reminder: The Hardy-Weinberg formula only gives us an estimate for a snapshot in time. We will have to calculate it again later, after various intervals, to determine if our population is evolving and in what way the allele frequencies are changing.<\/p>\n<h3 class=\"import-Normal\"><strong>Interpreting Evolutionary Change: Nonra<\/strong><strong>ndom Mating <\/strong><\/h3>\n<p class=\"import-Normal\">Once we have detected change occurring in a population, we need to consider which evolutionary processes might be the cause of the change. It is important to watch for nonrandom mating patterns, to see if they can be included or excluded as possible sources of variation in allele frequencies.<\/p>\n<p class=\"import-Normal\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1498\"><strong>Nonrandom <\/strong><strong>m<\/strong><strong>ating<\/strong><\/a> (also known as assortative mating) occurs when mate choice within a population follows a nonrandom pattern.<\/p>\n<p class=\"import-Normal\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1499\"><strong>Positive assortative mating<\/strong><\/a> patterns result from a tendency for individuals to mate with others who share similar phenotypes. This often happens based on body size. Taking as an example dog breeds, it is easier for two Chihuahuas to mate and have healthy offspring than it is for a Chihuahua and a St. Bernard to do so. This is especially true if the Chihuahua is the female and would have to give birth to giant St. Bernard pups.<\/p>\n<p class=\"import-Normal\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1500\"><strong>Negative assortative mating<\/strong><\/a> patterns occur when individuals tend to select mates with qualities different from their own. This is what is at work when humans choose partners whose pheromones indicate that they have different and complementary immune alleles, providing potential offspring with a better chance at a stronger immune system.<\/p>\n<p class=\"import-Normal\">Among domestic animals, such as pets and livestock, assortative mating is often directed by humans who decide which pairs will mate to increase the chances of offspring having certain desirable traits. This is known as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1501\"><strong>a<\/strong><strong>rtificial <\/strong><strong>s<\/strong><strong>election<\/strong><em>.<\/em><\/a><\/p>\n<p class=\"import-Normal\">Among humans, in addition to phenotypic traits, cultural traits such as religion and ethnicity may also influence assortative mating patterns.<\/p>\n<h3 class=\"import-Normal\"><strong>Defining a Species<\/strong><\/h3>\n<p class=\"import-Normal\"><em>Species<\/em> are organisms whose individuals are capable of breeding because they are biologically and behaviourally compatible to produce viable, fertile offspring. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1502\"><strong>Viable offspring<\/strong><\/a> are those offspring that are healthy enough to survive to adulthood. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1503\"><strong>Fertile offspring<\/strong><\/a> are able to reproduce successfully, resulting in offspring of their own. Both conditions must be met for individuals to be considered part of the same species. As you can imagine, these criteria complicate the identification of distinct species in fossilized remains of extinct populations. In those cases, we must examine how much phenotypic variation is typically found within a comparable modern-day species; we can then determine whether the fossilized remains fall within the expected range of variation for a single species.<\/p>\n<p class=\"import-Normal\">Some species have subpopulations that are regionally distinct. These are classified as separate <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1505\">subspecies<\/a><\/strong> because they have their own unique phenotypes and are geographically isolated from one another. However, if they do happen to encounter one another, they are still capable of successful interbreeding.<\/p>\n<p class=\"import-Normal\">There are many examples of sterile hybrids that are offspring of parents from two different species. For example, horses and donkeys can breed and have offspring together. Depending on which species is the mother and which is the father, the offspring are either called mules, or hennies. Mules and hennies can live full life spans but are not able to have offspring of their own. Likewise, tigers and lions have been known to mate and have viable offspring. Again, depending on which species is the mother and which is the father, these offspring are called either ligers or tigons. Like mules and hennies, ligers and tigons are unable to reproduce. In each of these cases, the mismatched set of chromosomes that the offspring inherit produce an adequate set of functioning genes for the hybrid offspring; however, once mixed and divided in meiosis, the gametes don\u2019t contain the full complement of genes needed for survival in the third generation.<\/p>\n<h3 class=\"import-Normal\"><strong>Micro- to Macroevolution<\/strong><\/h3>\n<p class=\"import-Normal\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1506\"><strong>Microevolution<\/strong><\/a> refers to changes in allele frequencies within breeding populations\u2014that is, within single species. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1507\"><strong>Macroevolution<\/strong><\/a> describes how the similarities and differences between species, as well as the phylogenetic relationships with other taxa, lead to changes that result in the emergence of new species. Consider our example of the peppered moth that illustrated microevolution over time, via directional selection favouring the peppered allele when the trees were clean and the dark pigment allele when the trees were sooty. Imagine that environmental regulations had cleaned up the air pollution in one part of the nation, while the coal-fired factories continued to spew soot in another area. If this went on long enough, it\u2019s possible that two distinct moth populations would eventually emerge\u2014one containing only the peppered allele and the other only harbouring the dark pigment allele.<\/p>\n<p class=\"import-Normal\">When a single population divides into two or more separate species, it is called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1508\"><strong>speciation<\/strong><\/a>. The changes that prevent successful breeding between individuals who descended from the same ancestral population may involve chromosomal rearrangements, changes in the ability of the sperm from one species to permeate the egg membrane of the other species, or dramatic changes in hormonal schedules or mating behaviours that prevent members from the new species from being able to effectively pair up.<\/p>\n<p class=\"import-Normal\">There are two types of speciation: allopatric and sympatric. <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1509\">Allopatric speciation<\/a><\/strong> is caused by long-term <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1510\"><strong>isolation<\/strong><\/a> (physical separation) of subgroups of the population (Figure 5.24). Something occurs in the environment\u2014perhaps a river changes its course and splits the group, preventing them from breeding with members on the opposite riverbank. Over many generations, new mutations and adaptations to the different environments on each side of the river may drive the two subpopulations to change so much that they can no longer produce fertile, viable offspring, even if the barrier is someday removed.<\/p>\n<figure style=\"width: 1000px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image23-2.png\" alt=\"Process of isolation leading to speciation, as described in the figure caption.\" width=\"1000\" height=\"379\" \/><figcaption class=\"wp-caption-text\">Figure 5.24: Isolation leading to speciation: a. original population before isolation; b. a barrier divides the population and prevents interbreeding between the two groups; c. time passes, and the populations become genetically distinct; d. after many generations, the two populations are no longer biologically or behaviourally compatible, thus can no longer interbreed, even if the barrier is removed. Credit: <a class=\"rId121\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-3\/\">Isolation Leading to Speciation (Figure 4.19)<\/a> original to <a class=\"rId122\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a class=\"rId123\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\"><strong>Sympatric speciation<\/strong> occurs when the population splits into two or more separate species while remaining located together <em>without<\/em> a physical barrier. This typically results from a new mutation that pops up among some members of the population that prevents them from successfully reproducing with anyone who does not carry the same mutation. This is seen particularly often in plants, as they have a higher frequency of chromosomal duplications.<\/p>\n<p class=\"import-Normal\">One of the quickest rates of speciation is observed in the case of adaptive radiation. <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1512\">Adaptive radiation<\/a><\/strong> refers to the situation in which subgroups of a single species rapidly diversify and adapt to fill a variety of ecological niches. An <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1513\"><strong>e<\/strong><strong>cological niche<\/strong><\/a> is a set of constraints and resources that is available in an environmental setting. Evidence for adaptive radiations is often seen after population bottlenecks. A mass disaster kills off many species, and the survivors have access to a new set of territories and resources that were either unavailable or much coveted and fought over before the disaster. The offspring of the surviving population will often split into multiple species, each of which stems from members in that first group of survivors who happened to carry alleles that were advantageous for a particular niche.<\/p>\n<p class=\"import-Normal\">The classic example of adaptive radiation brings us back to Charles Darwin and his observations of the many species of finches on the Galapagos Islands. We are still not sure how the ancestral population of finches first arrived on that remote Pacific Island chain, but they found themselves in an environment filled with various insects, large and tiny seeds, fruit, and delicious varieties of cactus. Some members of that initial population carried alleles that gave them advantages for each of these dietary niches. In subsequent generations, others developed new mutations, some of which were beneficial. These traits were selected for, making the advantageous alleles more common among their offspring. As the finches spread from one island to the next, they would be far more likely to find mates among the birds on their new island. Birds feeding in the same area were then more likely to mate together than birds who have different diets, contributing to additional assortative mating. Together, these evolutionary mechanisms caused rapid speciation that allowed the new species to make the most of the various dietary niches (Figure 5.25).<\/p>\n<figure style=\"width: 619px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image24-1.png\" alt=\"A family tree of finches with different sized beaks.\" width=\"619\" height=\"325\" \/><figcaption class=\"wp-caption-text\">Figure 5.25: Darwin\u2019s finches demonstrating Adaptive Radiation. Credit: <a class=\"rId125\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-3\/\">Darwin\u2019s finches (Figure 4.20)<\/a> original to <a class=\"rId126\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a class=\"rId127\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">In today\u2019s modern world, understanding these evolutionary processes is crucial for developing immunizations and antibiotics that can keep up with the rapid mutation rate of viruses and bacteria. This is also relevant to our food supply, which relies, in large part, on the development of herbicides and pesticides that keep up with the mutation rates of pests and weeds. Viruses, bacteria, agricultural pests, and weeds have all shown great flexibility in developing alleles that make them resistant to the latest medical treatment, pesticide, or herbicide. Billion-dollar industries have specialized in trying to keep our species one step ahead of the next mutation in the pests and infectious diseases that put our survival at risk.<\/p>\n<h2>Cultural Connections and Contemporary Implications<\/h2>\n<h5>Sex within Culture and Biology<\/h5>\n<p>Research on bonobos (<em>Pan paniscus<\/em>) reveals a primate species whose social system relies heavily on affiliative and erotic behaviours rather than aggression. Bonobos live in fission\u2013fusion communities in Central African forests, where males remain in their natal groups and females migrate at adolescence. While sexual engagement is a large part of their social ecosystem, we see reproductive rates remain low, with females giving birth roughly every four to five years.<\/p>\n<p>Social cohesion among bonobos is strongly shaped by sexuality. Individuals engage frequently in diverse erotic behaviours; genital rubbing, oral contact, face-to-face copulation, and various forms of genital-to-genital stimulation are performed, but are not directly tied to reproduction. Through these modes of erotic sociality, tension is reduced, conflict is resolved, and food sharing is facilitated; all of which appear to function as peacemaking mechanisms integral to group stability. In this context, sexual pleasure is decoupled from reproduction, a parallel also found in human societies. Humans, like most primates, do not biologically mate for life; monogamy is a social contract, not a biological reality (Fuentes, 2012). Long-term exclusive mating is rare among primate species, and even in socially monogamous human groups, extra-pair copulations contribute substantially to reproductive outcomes.<\/p>\n<p>Human sexual development operates across genetic, hormonal, anatomical, and cultural levels. Biological traits such as chromosomal patterns or endocrine shifts interact with the social categories of gender, including transgender and transsexual identities (Fausto-Sterling, 1993, 2000a,b). Cultural expectations shape how sexual bodies are interpreted, often projecting ideological assumptions onto biological processes. This dynamic is exemplified in Emily Martin\u2019s (1991) critique of gendered metaphors in reproductive medical science, where egg and sperm are frequently described using stereotypically feminine or masculine language. Sexuality in humans is also neurologically mediated; as theorized by Freud, who suggested that humans possess undirected libidinal drives which society channels and constrains. With sex maintaining such sociocultural importance to humans, the anthropology of sex helps emphasize sexual practices, identities, and desires which emerge from the interplay of individual experience, interpersonal relationships, and broader cultural, political, and economic structures.<\/p>\n<h5>Archaeologies of Sexuality and the Future of Sex<\/h5>\n<p>Early archaeology commonly dismissed or obscured non-normative sexual imagery, classifying it under \u2018pornography\u2019 or \u2018Whore-Writing\u2019, a term introduced by the archaeologist M\u00fcller in 1850 to describe and demonize sexually explicit artifacts from Pompeii. Such categorizations reflected Victorian moral regimes rather than empirical assessment. Recent work highlights greater sexual and gender diversity in ancient material culture. Thousands of Ecuadorian clay figurines from 4400 BCE\u20131500 CE display non-binary and mixed-gender features, all of which were long-ignored or rationalized by earlier researchers (Ugalde, 2019). Later figurines exhibit more explicitly gendered poses, suggesting the gradual rise of patriarchal social structures.\u00a0<span style=\"margin: 0px;padding: 0px\">Simone de Beauvoir\u2019s\u00a0<em>The Second Sex<\/em> (1949) further explores this, arguing<\/span>\u00a0that women have historically been constructed as \u201cthe Other,\u201d a philosophical and social position that has shaped interpretations of sex, gender, and embodiment across cultures.<\/p>\n<p>Contemporary technological shifts prompt reconsideration of intimacy, embodiment, and sexual relationships. Robotics, avatars, and artificial companions raise questions about authenticity, relationality, and human\u2013machine attachment. Sherry Turkle (2011) argues that as people become increasingly anxious about interpersonal vulnerability, they may turn to machines for controlled forms of companionship and emotional safety. These developments illuminate broader transformations in how societies conceptualize relationships, desire, and human connection. They also challenge us to reconsider what counts as intimacy, what makes a relationship meaningful, and what ethical considerations arise when technologies substitute or reshape human sexual and emotional experience.<\/p>\n<h4>Discussion questions<\/h4>\n<ul>\n<li>With the rise of artificial companions, how might concepts such as intimacy, love, relationships, and sexuality be reconfigured? What might these changes reveal about how we understand human connection?<\/li>\n<li>How does studying sex and sexuality in other primates, such as bonobos, help us understand human sexuality and social behaviour? What are the limitations of using primates to understand humans?<\/li>\n<li>How might gendered metaphors and stereotypes influence the way scientific knowledge is produced and interpreted? Can you think of other examples where cultural assumptions have shaped scientific explanations?<\/li>\n<\/ul>\n<div class=\"textbox shaded\">\n<h2 class=\"import-Normal\">Review Questions<strong><br \/>\n<\/strong><\/h2>\n<ul>\n<li>Summarize the Modern Synthesis and provide several examples of how it is relevant to questions and problems in our world today.<\/li>\n<li>You inherit a house from a long-lost relative that contains a fancy aquarium, filled with a variety of snails. The phenotypes include large snails and small snails; red, black, and yellow snails; and solid, striped, and spotted snails. Devise a series of experiments that would help you determine how many snail species are present in your aquarium.<\/li>\n<li>Match the correct force of evolution with the correct real-world example:<br \/>\na. Mutationi. 5-alpha reductase deficiency<br \/>\nb. Genetic Driftii. Peppered Moths<br \/>\nc. Gene Flowiii. Neurofibromatosis Type 1<br \/>\nd. Natural Selectioniv. Scutellata Honey Bees<\/li>\n<li>Imagine a population of common house mice (<em>Mus musculus<\/em>). Draw a comic strip illustrating how mutation, genetic drift, gene flow, and natural selection might transform this population over several (or more) generations.<\/li>\n<li>\n<p class=\"import-Normal\">The many breeds of the single species of domestic dog (<em>Canis<\/em> <em>familiaris<\/em>) provide an extreme example of microevolution. Discuss why this is the case. What future scenarios can you imagine that could potentially transform the domestic dog into an example of macroevolution?<\/p>\n<\/li>\n<li>\n<p class=\"import-Normal\">The ability to roll one\u2019s tongue (lift the outer edges of the tongue to touch each other, forming a tube) is a dominant trait. In a small town of 1,500 people, 500 can roll their tongues. Use the Hardy-Weinberg formula to determine how many individuals in the town are homozygous dominant, heterozygous, and homozygous recessive.<\/p>\n<\/li>\n<\/ul>\n<\/div>\n<h2 class=\"import-Normal\">Key Terms<strong><br \/>\n<\/strong><\/h2>\n<p class=\"import-Normal\"><strong>5-alpha reductase deficiency<\/strong>: An autosomal recessive syndrome that manifests when a child having both X and Y sex chromosomes inherits two nonfunctional (mutated) copies of the SRD5A2 gene, producing a deficiency in a hormone necessary for development in infancy of typical male genitalia. These children often appear at birth to have female genitalia, but they develop a penis and other sexual characteristics when other hormones kick in during puberty.<\/p>\n<p class=\"import-Normal\"><strong>Adaptive radiation<\/strong>: The situation in which subgroups of a single species rapidly diversify and adapt to fill a variety of ecological niches.<\/p>\n<p class=\"import-Normal\"><strong>Admixture<\/strong>: A term often used to describe gene flow between human populations. Sometimes also used to describe gene flow between nonhuman populations.<\/p>\n<p class=\"import-Normal\"><strong>Allele frequency<\/strong>: The ratio, or percentage, of one allele compared to the other alleles for that gene within the study population.<\/p>\n<p class=\"import-Normal\"><strong>Alleles<\/strong>: Variant forms of genes.<\/p>\n<p class=\"import-Normal\"><strong>Allopatric speciation<\/strong>: Speciation caused by long-term isolation (physical separation) of subgroups of the population.<\/p>\n<p class=\"import-Normal\"><strong>Antibiotics<\/strong>: Medicines prescribed to treat bacterial infections.<\/p>\n<p class=\"import-Normal\"><strong>Artificial selection<\/strong>: Human-directed assortative mating among domestic animals, such as pets and livestock, designed to increase the chances of offspring having certain desirable traits.<\/p>\n<p class=\"import-Normal\"><strong>Asexual reproduction<\/strong>: Reproduction via mitosis, whereby offspring are clones of the parents.<\/p>\n<p class=\"import-Normal\"><strong>Autosomal dominant<\/strong>: A phenotype produced by a gene on an autosomal chromosome that is expressed, to the exclusion of the recessive phenotype, in heterozygotes.<\/p>\n<p class=\"import-Normal\"><strong>Autosomal recessive<\/strong>: A phenotype produced by a gene on an autosomal chromosome that is expressed only in individuals homozygous for the recessive allele.<\/p>\n<p class=\"import-Normal\"><strong>Balanced translocations<\/strong>: Chromosomal translocations in which the genes are swapped but no genetic information is lost.<\/p>\n<p class=\"import-Normal\"><strong>Balancing selection<\/strong>: A pattern of natural selection that occurs when the extremes of a trait are selected against, favouring the intermediate phenotype (a.k.a. stabilizing selection).<\/p>\n<p class=\"import-Normal\"><strong>Beneficial mutations<\/strong>: Mutations that produce some sort of an advantage to the individual.<\/p>\n<p class=\"import-Normal\"><strong>Benign<\/strong>: Noncancerous. Benign tumors may cause problems due to the area in which they are located (e.g., they might put pressure on a nerve or brain area), but they will not release cells that aggressively spread to other areas of the body.<\/p>\n<p class=\"import-Normal\"><strong>Caf\u00e9-au-lait spots (CALS)<\/strong>: Flat, brown birthmark-like spots on the skin, commonly associated with Neurofibromatosis Type 1.<\/p>\n<p class=\"import-Normal\"><strong>Chromosomal translocations<\/strong>: The transfer of DNA between nonhomologous chromosomes.<\/p>\n<p class=\"import-Normal\"><strong>Chromosomes<\/strong>: Molecules that carry collections of genes.<\/p>\n<p class=\"import-Normal\"><strong>Codons<\/strong>: Three-nucleotide units of DNA that function as three-letter \u201cwords,\u201d encoding instructions for the addition of one amino acid to a protein or indicating that the protein is complete.<\/p>\n<p class=\"import-Normal\"><strong>Cretaceous\u2013Paleogene extinction<\/strong>: A mass disaster caused by an asteroid that struck the earth approximately 66 million years ago and killed 75% of life on Earth, including all terrestrial dinosaurs. (a.k.a. K-Pg Extinction, Cretatious-Tertiary Extinction, and K-T Extinction).<\/p>\n<p class=\"import-Normal\"><strong>Crossover events<\/strong>: Chromosomal alterations that occur when DNA is swapped between homologous chromosomes while they are paired up during meiosis I.<\/p>\n<p class=\"import-Normal\"><strong>Cutaneous neurofibromas<\/strong>: Neurofibromas that manifest as spherical bumps on or just under the surface of the skin.<\/p>\n<p class=\"import-Normal\"><strong>Deleterious mutation<\/strong>: A mutation producing negative effects to the individual such as the beginnings of cancers or heritable disorders.<\/p>\n<p class=\"import-Normal\"><strong>Deletions<\/strong>: Mutations that involve the removal of one or more nucleotides from a DNA sequence.<\/p>\n<p class=\"import-Normal\"><strong>Derivative chromosomes<\/strong>: New chromosomal structures resulting from translocations.<\/p>\n<p class=\"import-Normal\"><strong><em>Dictyostelium discoideum<\/em><\/strong>: A species of social amoebae that has been widely used for laboratory research. Laboratory strains of <em>Dictyostelium discoideum <\/em>all carry mutations in the <em>NF1<\/em> gene, which is what allows them to survive on liquid media (agar) in Petri dishes.<\/p>\n<p class=\"import-Normal\"><strong>Directional selection<\/strong>: A pattern of natural selection in which one phenotype is favoured over the other, causing the frequencies of the associated advantageous alleles to gradually increase.<\/p>\n<p class=\"import-Normal\"><strong>Disruptive selection<\/strong>: A pattern of natural selection that occurs when both extremes of a trait are advantageous and intermediate phenotypes are selected against (a.k.a. diversifying selection).<\/p>\n<p class=\"import-Normal\"><strong>DNA repair mechanisms<\/strong>: Enzymes that patrol and repair DNA in living cells.<\/p>\n<p class=\"import-Normal\"><strong>DNA transposons<\/strong>: Transposons that are clipped out of the DNA sequence itself and inserted elsewhere in the genome.<\/p>\n<p class=\"import-Normal\"><strong>Ecological niche<\/strong>: A set of constraints and resources that are available in an environmental setting.<\/p>\n<p class=\"import-Normal\"><strong>Ellis-van Creveld syndrome<\/strong>: An autosomal recessive disorder characterized by short stature (dwarfism), polydactyly (the development of more than five digits [fingers or toes] on the hands or feet), abnormal tooth development, and heart defects. Estimated to affect approximately one in 60,000 individuals worldwide, among the Old Order Amish of Lancaster County, the rate is estimated to be as high as one in every 200 births.<\/p>\n<p class=\"import-Normal\"><strong>Evolution<\/strong>: A change in the allele frequencies in a population over time.<\/p>\n<p class=\"import-Normal\"><strong>Exons<\/strong>: The DNA sequences within a gene that directly encode protein sequences. After being transcribed into messenger RNA, the introns (DNA sequences within a gene that do not directly encode protein sequences) are clipped out, and the exons are pasted together prior to translation.<\/p>\n<p class=\"import-Normal\"><strong>Fertile offspring<\/strong>: Offspring that can successfully reproduce, resulting in offspring of their own.<\/p>\n<p class=\"import-Normal\"><strong>Founder effect<\/strong>: A type of genetic drift that occurs when members of a population leave the main or \u201cparent\u201d group and form a new population that no longer interbreeds with the other members of the original group.<\/p>\n<p class=\"import-Normal\"><strong>Frameshift mutations<\/strong>: Types of indels that involve the insertion or deletion of any number of nucleotides that is not a multiple of three. These \u201cshift the reading frame\u201d and cause all codons beyond the mutation to be misread.<\/p>\n<p class=\"import-Normal\"><strong>Gametes<\/strong>: The reproductive cells, produced through meiosis (a.k.a. germ cells or sperm or egg cells).<\/p>\n<p class=\"import-Normal\"><strong>Gene<\/strong>: A sequence of DNA that provides coding information for the construction of proteins.<\/p>\n<p class=\"import-Normal\"><strong>Gene flow<\/strong>: The movement of alleles from one population to another. This is one of the forces of evolution.<\/p>\n<p class=\"import-Normal\"><strong>Gene pool<\/strong>: The entire collection of genetic material in a breeding community that can be passed on from one generation to the next.<\/p>\n<p class=\"import-Normal\"><strong>Genetic drift<\/strong>: Random changes in allele frequencies within a population from one generation to the next. This is one of the forces of evolution.<\/p>\n<p class=\"import-Normal\"><strong>Genotype<\/strong>: The set of alleles that an individual has for a given gene.<\/p>\n<p class=\"import-Normal\"><strong>Genotype frequencies<\/strong>: The ratios or percentages of the different homozygous and heterozygous genotypes in the population.<\/p>\n<p class=\"import-Normal\"><strong><em>Guevedoces<\/em><\/strong>: The term coined locally in the Dominican Republic for the condition scientifically known as 5-alpha reductase deficiency. The literal translation is \u201cpenis at twelve.\u201d<\/p>\n<p class=\"import-Normal\"><strong>Hardy-Weinberg Equilibrium<\/strong>: A mathematical formula (<em>1=p<\/em><sup><em>2<\/em><\/sup><em> + 2pq + q<\/em><sup><em>2<\/em><\/sup> ) that allows estimation of the number and distribution of dominant and recessive alleles in a population.<\/p>\n<p class=\"import-Normal\"><strong>Harlequin ladybeetle<\/strong>: A species of ladybeetle, native to East Asia, that was introduced to Europe and the Americas as a form of pest control. After many decades of use, one of the North American strains developed the ability to reproduce in diverse environments, causing it to spread rapidly throughout the Americas, Europe, and Africa. It has hybridized with European strains and is now a major pest in its own right.<\/p>\n<p class=\"import-Normal\"><strong>Heterozygous genotype<\/strong>: A genotype comprising two different alleles.<\/p>\n<p class=\"import-Normal\"><strong>Homozygous genotype<\/strong>: A genotype comprising an identical set of alleles.<\/p>\n<p class=\"import-Normal\"><strong>Hybridization<\/strong>: A term often used to describe gene flow between nonhuman populations.<\/p>\n<p class=\"import-Normal\"><strong>Inbreeding<\/strong>: The selection of mates exclusively from within a small, closed population.<\/p>\n<p class=\"import-Normal\"><strong>Indels<\/strong>: A class of mutations that includes both insertions and deletions.<\/p>\n<p class=\"import-Normal\"><strong>Inherited mutation<\/strong>: A mutation that has been passed from parent to offspring.<\/p>\n<p class=\"import-Normal\"><strong>Insertions<\/strong>: Mutations that involve the addition of one or more nucleotides into a DNA sequence.<\/p>\n<p class=\"import-Normal\"><strong>Isolation<\/strong>: Prevention of a population subgroup from breeding with other members of the same species due to a physical barrier or, in humans, a cultural rule.<\/p>\n<p class=\"import-Normal\"><strong>Last Universal Common Ancestor (LUCA)<\/strong>: The ancient organism from which all living things on Earth are descended.<\/p>\n<p class=\"import-Normal\"><strong>Macroevolution<\/strong>: Changes that result in the emergence of new species, how the similarities and differences between species, as well as the phylogenetic relationships with other taxa, lead to changes that result in the emergence of new species.<\/p>\n<p class=\"import-Normal\"><strong>Malaria<\/strong>: A frequently deadly mosquito-borne disease caused by infection of the blood by a <em>Plasmodium<\/em> parasite.<\/p>\n<p class=\"import-Normal\"><strong>Malignant<\/strong>: Cancerous. Malignant tumors grow aggressively and their cells may metastasize (travel through the blood or lymph systems) to form new, aggressive tumors in other areas of the body.<\/p>\n<p class=\"import-Normal\"><strong>Microevolution<\/strong>: Changes in allele frequencies within breeding populations\u2014that is, within a single species.<\/p>\n<p class=\"import-Normal\"><strong>Modern Synthesis<\/strong>: The integration of Darwin\u2019s, Mendel\u2019s, and subsequent research into a unified theory of evolution.<\/p>\n<p class=\"import-Normal\"><strong>Monosomies<\/strong>: Conditions resulting from a nondisjunction event, in which a cell ends up with only one copy of a chromosome. In humans, a single X chromosome is the only survivable monosomy.<\/p>\n<p class=\"import-Normal\"><strong>Mutation<\/strong>: A change in the nucleotide sequence of the genetic code. This is one of the forces of evolution.<\/p>\n<p class=\"import-Normal\"><strong>Natural selection<\/strong>: An evolutionary process that occurs when certain phenotypes confer an advantage or disadvantage in survival and\/or reproductive success. This is one of the forces of evolution, and it was first identified by Charles Darwin.<\/p>\n<p class=\"import-Normal\"><strong>Negative assortative mating<\/strong>: A pattern that occurs when individuals tend to select mates with qualities different from their own.<\/p>\n<p class=\"import-Normal\"><strong>Neurofibromas<\/strong>: Nerve sheath tumors that are common symptoms of Neurofibromatosis Type 1.<\/p>\n<p class=\"import-Normal\"><strong>Neurofibromatosis Type 1<\/strong>: An autosomal dominant genetic disorder affecting one in every 3,000 people. It is caused by mutation of the <em>NF1<\/em> gene on Chromosome 17, resulting in a defective neurofibromin protein. The disorder is characterized by neurofibromas, caf\u00e9-au-lait spots, and a host of other potential symptoms.<\/p>\n<p class=\"import-Normal\"><strong>NF1<\/strong>: An abbreviation for Neurofibromatosis Type 1. When italicized, <em>NF1 <\/em>refers to the gene on Chromosome 17 that encodes the neurofibromin protein.<\/p>\n<p class=\"import-Normal\"><strong>Nondisjunction events<\/strong>: Chromosomal abnormalities that occur when the homologous chromosomes (in meiosis I) or sister chromatids (in meiosis II and mitosis) fail to separate after pairing. The result is that both chromosomes or chromatids end up in the same daughter cell, leaving the other daughter cell without any copy of that chromosome.<\/p>\n<p class=\"import-Normal\"><strong>Nonrandom mating<\/strong>: A scenario in which mate choice within a population follows a nonrandom pattern (a.k.a. assortative mating).<\/p>\n<p class=\"import-Normal\"><strong>Nonsynonymous mutation<\/strong>: A point mutation that causes a change in the resulting protein.<\/p>\n<p class=\"import-Normal\"><strong>Old Order Amish<\/strong>: A culturally isolated population in Lancaster County, Pennsylvania, that has approximately 50,000 current members, all of whom can trace their ancestry back to a group of approximately eighty individuals. This group has high rates of certain genetics disorders, including Ellis-van Creveld syndrome.<\/p>\n<p class=\"import-Normal\"><strong>Origins of life<\/strong>: How the first living organism came into being.<\/p>\n<p class=\"import-Normal\"><strong>Peacock<\/strong>: The male sex of the peafowl, famous for its large, colourful tail, which it dramatically displays to attract mates. (The female of the species is known as a peahen.)<\/p>\n<p class=\"import-Normal\"><strong>Peppered moth<\/strong>: A species of moth (<em>Biston betularia<\/em>) found in England that has light and dark phenotypes. During the Industrial Revolution, when soot blackened the trees, the frequency of the previously rare dark phenotype dramatically increased, as lighter-coloured moths were easier for birds to spot against the sooty trees. After environmental regulations eliminated the soot, the lighter-coloured phenotype gradually became most common again.<\/p>\n<p class=\"import-Normal\"><strong>Phenotype<\/strong>: The observable traits that are produced by a genotype.<\/p>\n<p class=\"import-Normal\"><strong>Phylogenetic tree of life<\/strong>: A family tree of all living organisms, based on genetic relationships.<\/p>\n<p class=\"import-Normal\"><strong>Phylogenies<\/strong>: Genetically determined family lineages.<\/p>\n<p class=\"import-Normal\"><strong><em>Plasmodium<\/em><\/strong>: A genus of mosquito-borne parasite. Several <em>Plasmodium<\/em> species cause malaria when introduced to the human bloodstream via a mosquito bite.<\/p>\n<p class=\"import-Normal\"><strong>Plexiform neurofibromas<\/strong>: Neurofibromas that involve whole branches of nerves, often giving the appearance that the surface of the skin is \u201cmelting.\u201d<\/p>\n<p class=\"import-Normal\"><strong>Point mutation<\/strong>: A single-letter (single-nucleotide) change in the genetic code, resulting in the substitution of one nucleic acid base for a different one.<\/p>\n<p class=\"import-Normal\"><strong>Polymorphisms<\/strong>: Multiple forms of a trait; alternative phenotypes within a given species.<\/p>\n<p class=\"import-Normal\"><strong>Population<\/strong>: A group of individuals who are genetically similar enough and geographically near enough to one another that they can breed and produce new generations of individuals.<\/p>\n<p class=\"import-Normal\"><strong>Population bottleneck<\/strong>: A type of genetic drift that occurs when the number of individuals in a population drops dramatically due to some random event.<\/p>\n<p class=\"import-Normal\"><strong>Positive assortative mating<\/strong>: A pattern that results from a tendency for individuals to mate with others who share similar phenotypes.<\/p>\n<p class=\"import-Normal\"><strong>Retrotransposons<\/strong>: Transposons that are transcribed from DNA into RNA, and then are \u201creverse transcribed,\u201d to insert the copied sequence into a new location in the DNA.<\/p>\n<p class=\"import-Normal\"><strong>Scutellata honey bees<\/strong>: A strain of honey bees that resulted from the hybridization of African and European honey bee subspecies. These bees were accidentally released into the wild in 1957 in Brazil and have since spread throughout South and Central America and into the United States. Also known as \u201ckiller bees,\u201d they tend to be very aggressive in defence of their hives and have caused many fatal injuries to humans and livestock.<\/p>\n<p class=\"import-Normal\"><strong>Sexual reproduction<\/strong>: Reproduction via meiosis and combination of gametes. Offspring inherit genetic material from both parents.<\/p>\n<p class=\"import-Normal\"><strong>Sexual selection<\/strong>: An aspect of natural selection in which the selective pressure specifically affects reproductive success (the ability to successfully breed and raise offspring).<\/p>\n<p class=\"import-Normal\"><strong>Sickle cell anemia<\/strong>: An autosomal recessive genetic disorder that affects millions of people worldwide. It is most common in Africa, countries around the Mediterranean Sea, and eastward as far as India. Homozygotes for the recessive allele develop the disorder, which produce misshapen red blood cells that cause iron deficiency, painful episodes of oxygen-deprivation in localized tissues, and a host of other symptoms. In heterozygotes, though, the sickle cell allele confers a greater resistance to malaria.<\/p>\n<p class=\"import-Normal\"><strong>Somatic cells<\/strong>: The cells of our organs and other body tissues (all cells except gametes) that replicate by mitosis.<\/p>\n<p class=\"import-Normal\"><strong>Speciation<\/strong>: The process by which a single population divides into two or more separate species.<\/p>\n<p class=\"import-Normal\"><strong>Species<\/strong>: Organisms whose individuals are capable of breeding because they are biologically and behaviourally compatible to produce viable, fertile offspring.<\/p>\n<p class=\"import-Normal\"><strong>Spontaneous mutation<\/strong>: A mutation that occurs due to random chance or unintentional exposure to mutagens. In families, a spontaneous mutation is the first case, as opposed to mutations that are inherited from parents.<\/p>\n<p class=\"import-Normal\"><strong>Subspecies<\/strong>: A distinct subtype of a species. Most often, this is a geographically isolated population with unique phenotypes; however, it remains biologically and behaviourally capable of interbreeding with other populations of the same species.<\/p>\n<p class=\"import-Normal\"><strong>Sympatric speciation<\/strong>: When a population splits into two or more separate species while remaining located together without a physical (or cultural) barrier.<\/p>\n<p class=\"import-Normal\"><strong>Synonymous mutation<\/strong>: A point mutation that does not change the resulting protein.<\/p>\n<p class=\"import-Normal\"><strong>Transposable elements<\/strong>: Fragments of DNA that can \u201cjump\u201d around in the genome.<\/p>\n<p class=\"import-Normal\"><strong>Transposon<\/strong>: Another term for \u201ctransposable element.\u201d<\/p>\n<p class=\"import-Normal\"><strong>Trisomies<\/strong>: Conditions in which three copies of the same chromosome end up in a cell, resulting from a nondisjunction event. Down syndrome, Edwards syndrome, and Patau syndrome are trisomies.<\/p>\n<p class=\"import-Normal\"><strong>Unbalanced translocations<\/strong>: Chromosomal translocations in which there is an unequal exchange of genetic material, resulting in duplication or loss of genes.<\/p>\n<p class=\"import-Normal\"><strong>UV crosslinking<\/strong>: A type of mutation in which adjacent thymine bases bind to one another in the presence of UV light.<\/p>\n<p class=\"import-Normal\"><strong>Viable offspring<\/strong>: Offspring that are healthy enough to survive to adulthood.<\/p>\n<p class=\"import-Normal\"><strong>Xeroderma pigmentosum<\/strong>: An autosomal recessive disease in which DNA repair mechanisms do not function correctly, resulting in a host of problems especially related to sun exposure, including severe sunburns, dry skin, heavy freckling, and other pigment changes.<\/p>\n<h2 class=\"import-Normal\">For Further Exploration<\/h2>\n<p>Explore Evolution on <a href=\"https:\/\/www.hhmi.org\/biointeractive\/evolution-collection\">HHMI\u2019s Biointeractive website<\/a>.<\/p>\n<p>Teaching Evolution through <a href=\"https:\/\/humanorigins.si.edu\/education\/teaching-evolution-through-human-examples\">Human Examples, Smithsonian Museum of Natural History websites<\/a>.<\/p>\n<h2 class=\"import-Normal\">References<\/h2>\n<p class=\"import-Normal\">Bloomfield, Gareth, David Traynor, Sophia P. Sander, Douwe M. Veltman, Justin A. Pachebat, and Robert R. Kay. 2015. \u201cNeurofibromin Controls Macropinocytosis and Phagocytosis in <em>Dictyostelium<\/em>.\u201d <em>eLife<\/em> 4:e04940.<\/p>\n<p class=\"import-Normal\">Chaix, Rapha\u00eblle, Chen Cao, and Peter Donnelly. 2008. \u201cIs Mate Choice in Humans MHC-Dependent?\u201d <em>PLoS Genetics<\/em> 4 (9): e1000184.<\/p>\n<p class=\"import-Normal\">Cook, Laurence M. 2003. \"The Rise and Fall of the <em>Carbonaria<\/em> Form of the Peppered Moth.\" <em>The Quarterly Review of Biology<\/em> 78 (4): 399\u2013417.<\/p>\n<p class=\"import-Normal\">Cota, Bruno C\u00e9zar Lage, Jo\u00e3o Gabriel Marques Fonseca, Luiz Oswaldo Carneiro Rodrigues, Nilton Alves de Rezende, Pollyanna Barros Batista, Vincent Michael Riccardi, and Luciana Macedo de Resende. 2018. \u201cAmusia and Its Electrophysiological Correlates in Neurofibromatosis Type 1.\u201d <em>Arquivos de Neuro-Psiquiatria<\/em> 76 (5): 287\u2013295.<\/p>\n<p class=\"import-Normal\">D\u2019Asdia, Maria Cecilia, Isabella Torrente, Federica Consoli, Rosangela Ferese, Monia Magliozzi, Laura Bernardini, Valentina Guida, et al. 2013. \u201cNovel and Recurrent EVC and EVC2 Mutations in Ellis-van Creveld Syndrome and Weyers Acrofacial Dyostosis.\u201d <em>European Journal of Medical Genetics<\/em> 56 (2): 80\u201387.<\/p>\n<p>de Beauvoir, S. (2009). <em>The Second Sex<\/em> (C. Borde &amp; S. Malovany-Chevallier, Trans.). Vintage Books. (Original work published 1949)<\/p>\n<p class=\"import-Normal\">Dobzhansky, Theodosius. 1937. <em>Genetics and the Origin of Species. <\/em>Columbia University Biological Series. New York: Columbia University Press.<\/p>\n<p class=\"import-Normal\">Facon, Beno\u00eet, Laurent Crespin, Anne Loiseau, Eric Lombaert, Alexandra Magro, and Arnaud Estoup. 2011. \u201cCan Things Get Worse When an Invasive Species Hybridizes? The Harlequin Ladybird <em>Harmonia axyridis<\/em> in France as a Case Study.\u201d <em>Evolutionary Applications<\/em> 4 (1): 71\u201388.<\/p>\n<p>Fausto-Sterling, A. (1993). The five sexes: Why male and female are not enough. <em>The Sciences;<\/em> 33(2):20\u201325.<\/p>\n<p>Fausto-Sterling, A. (2000a). The Five Sexes Revisited. <em>The Sciences; <\/em>40(4):18-23<\/p>\n<p>Fausto-Sterling, A. (2000b). <em>Sexing the body: Gender politics and the construction of sexuality<\/em>. Basic Books.<\/p>\n<p class=\"import-Normal\">Fisher, Ronald A. 1919. \"The Correlation between Relatives on the Supposition of Mendelian Inheritance.\" <em>Transactions of the Royal Society of Edinburgh<\/em> 52 (2): 399\u2013433.<\/p>\n<p class=\"import-Normal\">Ford, E. B. 1942. <em>Genetics for Medical Students<\/em>. London: Methuen.<\/p>\n<p class=\"import-Normal\" style=\"background-color: #ffffff\">Ford, E. B. 1949. <em>Mendelism and Evolution<\/em>. London: Methuen.<\/p>\n<p>Fuentes, A. (2012). <em>Race, monogamy, and other lies they told you: Busting myths about human nature<\/em>. University of California Press.<\/p>\n<p class=\"import-Normal\">Grant, Bruce S. 1999. \u201cFine-tuning the Peppered Moth Paradigm.\u201d <em>Evolution<\/em> 53 (3): 980\u2013984.<\/p>\n<p class=\"import-Normal\">Haldane, J. B. S. 1924. \u201cA Mathematical Theory of Natural and Artificial Selection (Part 1).\u201d <em>Transactions of the Cambridge Philosophical Society<\/em> 23 (2):19\u201341.<\/p>\n<p>Hoelzel, A. R., Gkafas, G. A., Kang, H., Sarigol, F., Le Boeuf, B., Costa, D. P., Beltran, R. S., Reiter, J., Robinson, P. W., McInerney, N., Seim, I., Sun, S., Fan, G., &amp; Li, S. (2024). Genomics of post-bottleneck recovery in the northern elephant seal. Nature Ecology &amp; Evolution, 8, 686\u2013694. https:\/\/doi.org\/10.1038\/s41559-024-02337-4<\/p>\n<p>Hurst, L. D. (1996). Why are there only two sexes? <em>Proceedings of the Royal Society, London B<\/em>, 263; 415-422.<\/p>\n<p class=\"import-Normal\">Imperato-McGinley, J., and Y.-S. Zhu. 2002. \u201cAndrogens and Male Physiology: The Syndrome of 5 Alpha-Reductase-2 Deficiency.\u201d <em>Molecular and Cellular Endocrinology <\/em>198 (1-2): 51\u201359.<\/p>\n<p class=\"import-Normal\">Jablonski, David, and W. G. Chaloner. 1994. \"Extinctions in the Fossil Record.\u201d <em>Philosophical Transactions of the Royal Society of London B: Biological Sciences<\/em> 344 (1307): 11\u201317.<\/p>\n<p>Kinsey, A. C., Pomeroy, W. B., &amp; Martin, C. E. (1948). <em>Sexual behavior in the human male<\/em>. W.B. Saunders.<\/p>\n<p>Kinsey, A. C., Pomeroy, W. B., Martin, C. E., &amp; Gebhard, P. H. (1953). <em>Sexual behavior in the human female<\/em>. W.B. Saunders.<\/p>\n<p class=\"import-Normal\">Livi-Bacci, Massimo. 2006. \u201cThe Depopulation of Hispanic America after the Conquest.\u201d <em>Population Development and Review<\/em> 32 (2): 199\u2013232.<\/p>\n<p class=\"import-Normal\">Lombaert, Eric, Thomas Guillemaud, Jean-Marie Cornuet, Thibaut Malausa, Beno\u00eet Facon, and Arnaud Estoup. 2010. \"Bridgehead Effect in the Worldwide Invasion of the Biocontrol Harlequin Ladybird.\u201d <em>PLoS ONE<\/em> 5 (3): e9743.<\/p>\n<p>Martin, E. (1991). The egg and the sperm: How science has constructed a romance based on stereotypical male\u2013female roles. <em>Signs,<\/em> 16(3), 485\u2013501.<\/p>\n<p class=\"import-Normal\">Martins, Aline Stangherlin, Ann Kristine Jansen, Luiz Oswaldo Carneiro Rodrigues, Camila Maria Matos, Marcio Leandro Ribeiro Souza, Juliana Ferreira de Souza, Maria de F\u00e1tima Haueisen Sander Diniz, et al. 2016. \u201cLower Fasting Blood Glucose in Neurofibromatosis Type 1.\u201d <em>Endocrine Connections<\/em> 5 (1): 28\u201333.<\/p>\n<p class=\"import-Normal\">Pickering, Gary, James Lin, Roland Riesen, Andrew Reynolds, Ian Brindle, and George Soleas. 2004. \"Influence of <em>Harmonia axyridis<\/em> on the Sensory Properties of White and Red Wine.\" <em>American Journal of Enology and Viticulture<\/em> 55 (2): 153\u2013159.<\/p>\n<p class=\"import-Normal\">Repunte-Canonigo Vez, Melissa A. Herman, Tomoya Kawamura, Henry R. Kranzler, Richard Sherva, Joel Gelernter, Lindsay A. Farrer, Marisa Roberto, and Pietro Paolo Sanna. 2015. \u201cNF1 Regulates Alcohol Dependence-Associated Excessive Drinking and Gamma-Aminobutyric Acid Release in the Central Amygdala in Mice and Is Associated with Alcohol Dependence in Humans.\u201d <em>Biological Psychiatry<\/em> 77 (10): 870\u2013879.<\/p>\n<p class=\"import-Normal\">Riccardi, Vincent M. 1992. <em>Neurofibromatosis: Phenotype, Natural History, and Pathogenesis.<\/em> Baltimore: Johns Hopkins University Press.<\/p>\n<p class=\"import-Normal\">Sanford, Malcolm T. 2006. \"The Africanized Honey Bee in the Americas: A Biological Revolution with Human Cultural Implications, Part V\u2014Conclusion.\" <em>American Bee Journal <\/em>146 (7): 597\u2013599.<\/p>\n<p class=\"import-Normal\">Sanna, Pietro Paolo, Cindy Simpson, Robert Lutjens, and George Koob. 2002. \u201cERK Regulation in Chronic Ethanol Exposure and Withdrawal.\u201d <em>Brain Research<\/em> 948 (1\u20132): 186\u2013191.<\/p>\n<p>Turkle, S. (2011). <em>Alone together: Why we expect more from technology and less from each other<\/em>. Basic Books.<\/p>\n<p>Ugalde, Mar\u00eda Fernanda. 2019. \u201cThe Rebel Potters: A Review of Gender Relations, Female Oppression, and Patriarchy from the Perspective of Ecuadorian Archaeology.\u201d Translated by Tiziana Laudato. <em>Ant\u00edpoda. Revista de Antropolog\u00eda y Arqueolog\u00eda<\/em> 36: 1-23. https:\/\/doi.org\/10.7440\/antipoda36.2019.03<\/p>\n<p>Weber, DianaS., Stewart, B. S., Garza, J. Carlos., &amp; Lehman, N. (2000). An empirical genetic assessment of the severity of the northern elephant seal population bottleneck. Current Biology, 10(20), 1287\u20131290. https:\/\/doi.org\/10.1016\/s0960-9822(00)00759-4<\/p>\n<p class=\"import-Normal\">World Health Organization. 1996. \u201cControl of Hereditary Disorders: Report of WHO Scientific meeting (1996).\u201d WHO Technical Reports 865. Geneva: World Health Organization.<\/p>\n<p class=\"import-Normal\">World Health Organization. 2017. \u201cGlobal Priority List of Antibiotic-Resistant Bacteria to Guide Research, Discovery, and Development of New Antibiotics.\u201d Global Priority Pathogens List, February 27. Geneva: World Health Organization. https:\/\/www.who.int\/medicines\/publications\/WHO-PPL-Short_Summary_25Feb-ET_NM_WHO.pdf.<\/p>\n<p class=\"import-Normal\">Wright, Sewall. 1932. \"The Roles of Mutation, Inbreeding, Crossbreeding, and Selection in Evolution.\" <em>Proceedings of the Sixth International Congress on Genetics<\/em> 1 (6): 356\u2013366.<\/p>\n<h2 class=\"import-Normal\">Acknowledgement<strong><br \/>\n<\/strong><\/h2>\n<p class=\"import-Normal\">Many thanks to Dr. Vincent M. Riccardi for sharing his vast knowledge of neurofibromatosis and for encouraging me to explore it from an anthropological perspective.<\/p>\n<\/div>\n<\/div>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1695_1850\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1695_1850\"><div tabindex=\"-1\"><div class=\"__UNKNOWN__\">\n<div class=\"textbox\">\n<h6>Student contributors for this chapter from Salinda Hess' ANTH 203: Corin Laberge, Hazel Moorcroft, Isabella Michel, Julian J. Pantoja Quiroz<\/h6>\n<p>Learn more about <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/about-the-authors\/\">authors and editors<\/a>,<a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/student-contributors\/\"> Hess' student contributions<\/a>, and <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/versioning-history\/\">versioning history<\/a>.<\/p>\n<div class=\"textbox textbox--learning-objectives\">\n<header class=\"textbox__header\">\n<h2 class=\"textbox__title\">Learning Objectives<\/h2>\n<\/header>\n<div class=\"textbox__content\">\n<ul>\n<li class=\"import-Normal\">Outline a 21st-century perspective of the Modern Synthesis.<\/li>\n<li class=\"import-Normal\">Define populations and population genetics as well as the methods used to study them.<\/li>\n<li class=\"import-Normal\">Identify the forces of evolution and become familiar with examples of each.<\/li>\n<li class=\"import-Normal\">Discuss the evolutionary significance of mutation, genetic drift, gene flow, and natural selection.<\/li>\n<li class=\"import-Normal\">Explain how allele frequencies can be used to study evolution as it happens.<\/li>\n<li class=\"import-Normal\">Contrast micro- and macroevolution.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<p>It\u2019s hard for us, with our typical human life spans of less than 100 years, to imagine all the way back, 3.8 billion years ago, to the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1442\">origins of life<\/a><\/strong>. Scientists still study and debate how life came into being and whether it originated on Earth or in some other region of the universe (including some scientists who believe that studying evolution can reveal the complex processes that were set in motion by God or a higher power). What we do know is that a living single-celled organism was present on Earth during the early stages of our planet\u2019s existence. This organism had the potential to reproduce by making copies of itself, just like bacteria, many amoebae, and our own living cells today. In fact, with modern technologies, we can now trace genetic lineages, or <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1290\">phylogenies<\/a><\/strong>, and determine the relationships between all of today\u2019s living organisms\u2014eukaryotes (animals, plants, fungi, etc.), archaea, and bacteria\u2014on the branches of the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1444\">phylogenetic tree of life<\/a><\/strong> (Figure 5.1).<\/p>\n<figure style=\"width: 675px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2023\/02\/image1-1.png\" alt=\"Branches lead off of a single celled universal ancestor to images of bacteria, archaea, and eukarya (represented by a mouse, mushroom, and fern, among others).\" width=\"675\" height=\"475\" \/><figcaption class=\"wp-caption-text\">Figure 5.1: Phylogenetic tree of life illustrating probable relationships between the single-celled Last Universal Common Ancestor (LUCA) and select examples of bacteria, archaea, and eukaryotes. Major evolutionary developments, including independent evolution of multicellularity, photosynthesis, and respiration, are indicated along the branches. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available<\/a>. Credit: <a class=\"rId11\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Cladograma_dos_Dom%C3%ADnios_e_Reinos.png\">Cladograma dos Dominios e Reinos<\/a> by <a class=\"rId12\" href=\"https:\/\/commons.wikimedia.org\/wiki\/User:MarceloTeles\">MarceloTeles<\/a> has been modified (English labels replace Portuguese) and is under a <a class=\"rId13\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/deed.en\">CC BY-SA 4.0 License<\/a>..<\/figcaption><\/figure>\n<p class=\"import-Normal\">Looking at the common sequences in modern genomes, we can even make educated guesses about the likely genetic sequence of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1446\"><strong>Last Universal Common Ancestor (LUCA)<\/strong><\/a> of all living things. Through a wondrous series of mechanisms and events over nearly four billion years, that ancient single-celled organism gave rise to the rich diversity of species that fill the lands, seas, and skies of our planet. This chapter explores the mechanisms by which that amazing transformation occurred and considers some of the crucial scientific experiments that shaped our current understanding of the evolutionary process.<\/p>\n<h2 class=\"import-Normal\">Population Genetics<\/h2>\n<h3 class=\"import-Normal\"><strong>Defining Populations and the Variations <\/strong><strong>w<\/strong><strong>ithin Them<\/strong><\/h3>\n<p class=\"import-Normal\">One of the major breakthroughs in understanding the mechanisms of evolutionary change came with the realization that evolution takes place at the level of populations, not within individuals. In the biological sciences, a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1454\"><strong>p<\/strong><strong>opulation<\/strong><\/a> is defined as a group of individuals of the same <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1456\"><strong>species<\/strong><\/a> who are geographically near enough to one another that they can breed and produce new generations of individuals.<\/p>\n<p class=\"import-Normal\">For the purpose of studying evolution, we recognize populations by their even smaller units: genes. Remember, a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1458\"><strong>gene<\/strong><\/a> is the basic unit of information that encodes the proteins needed to grow and function as a living organism. Each gene can have multiple <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_738\">alleles<\/a><\/strong>, or variants\u2014each of which may produce a slightly different protein. Each individual, for genetic inheritance purposes, carries a collection of genes that can be passed down to future generations. For this reason, in population genetics, we think of populations as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1462\"><strong>gene pools<\/strong><\/a>, which refers to the entire collection of genetic material in a breeding community that can be passed on from one generation to the next.<\/p>\n<p class=\"import-Normal\">For genes carried on our human chromosomes (our nuclear DNA), we inherit two copies of each, one from each parent. This means we may carry two of the same alleles (a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1464\"><strong>homozygous genotype<\/strong><\/a>) or two different alleles (a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1466\"><strong>heterozygous<\/strong> <strong>genotype<\/strong><\/a>) for each nuclear gene.<\/p>\n<h3 class=\"import-Normal\"><strong>Defining Evolution <\/strong><\/h3>\n<p class=\"import-Normal\">In order to understand evolution, it\u2019s crucial to remember that evolution is always studied at the population level. Also, if a population were to stay exactly the same from one generation to the next, it would not be evolving. So evolution requires both a population of breeding individuals and some kind of a genetic change occurring within it. Thus, the simple definition of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1468\"><strong>evolution<\/strong><\/a> is a change in the allele frequencies in a population over time. What do we mean by allele frequencies? <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1470\"><strong>Allele frequencies<\/strong> <\/a>refer to the ratio, or percentage, of one allele (one variant of a gene) compared to the other alleles for that gene within the study population (Figure 5.2). By contrast, <strong>genotype frequencies<\/strong> are the ratios or percentages of the different homozygous and heterozygous genotypes in the population. Because we carry two alleles per <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_736\">genotype<\/a><\/strong>, the total count of alleles in a population will usually be exactly double the total count of genotypes in the same population (with the exception being rare cases in which an individual carries a different number of chromosomes than the typical two; e.g., Down syndrome results when a child carries three copies of Chromosome 21).<\/p>\n<figure style=\"width: 652px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image2.jpg\" alt=\"Genotypes are represented as combinations of alleles and allele frequencies.\" width=\"652\" height=\"883\" \/><figcaption class=\"wp-caption-text\">Figure 5.2: Population evolution can be measured by allele frequency changes. This diagram illustrates the differences between genotype frequencies and allele frequencies, as well as how they can be measured in a population of snapdragon flowers. The lower portion of the diagram also depicts how evolution is recognized as allele frequencies change in a population over time. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available<\/a>. Credit: Population evolution original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Katie Nelson and Beth Shook is a collective work under a <a class=\"rId15\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\">CC BY-NC 4.0 License<\/a>. [Includes <a class=\"rId16\" href=\"https:\/\/pixabay.com\/vectors\/snapdragon-flower-pink-lilac-plant-146850\/\">Snapdragon-flower-pink-lilac<\/a> by <a class=\"rId17\" href=\"https:\/\/pixabay.com\/users\/openclipart-vectors-30363\/\">OpenClipart-Vectors<\/a>, <a class=\"rId18\" href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/cc0\/\">public domain (CC0)<\/a> under a <a class=\"rId19\" href=\"https:\/\/pixabay.com\/service\/terms\/\">Pixabay License<\/a>.]<\/figcaption><\/figure>\n<h2 class=\"import-Normal\">The Forces of Evolution<\/h2>\n<p class=\"import-Normal\">Today, we recognize that evolution takes place through a combination of mechanisms: mutation, genetic drift, gene flow, and natural selection. These mechanisms are called the \u201cforces of evolution\u201d; together they account for all the genotypic variation observed in the world today. Keep in mind that each of these forces was first defined and then tested\u2014and retested\u2014through the experimental work of the many scientists who contributed to the Modern Synthesis.<\/p>\n<h3 class=\"import-Normal\"><strong>Mutation<\/strong><\/h3>\n<p class=\"import-Normal\">The first force of evolution we will discuss is mutation, and for good reason: mutation is the original source of all the genetic variation found in every living thing. Imagine all the way back in time to the very first single-celled organism, floating in Earth\u2019s primordial sea. Based on what we observe in simple, single-celled organisms today, that organism probably spent its lifetime absorbing nutrients and dividing to produce cloned copies of itself. While the numbers of individuals in that population would have grown (as long as the environment was favourable), nothing would have changed in that perfectly cloned population. There would not have been variety among the individuals. It was only through a copying error\u2014the introduction of a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1474\"><strong>mutation<\/strong><\/a>, or change, into the genetic code\u2014that new alleles were introduced into the population.<br style=\"clear: both\" \/><br style=\"clear: both\" \/>After many generations have passed in our primordial population, mutations have created distinct chromosomes. The cells are now amoeba-like, larger than many of their tiny bacterial neighbours, who have long since become their favourite source of nutrients. Without mutation to create this diversity, all living things would still be identical to LUCA, our universal ancestor (Figure 5.3).<\/p>\n<figure style=\"width: 663px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image3-2.png\" alt=\"Universal Ancestor linked to the Eukarya branch.\" width=\"663\" height=\"338\" \/><figcaption class=\"wp-caption-text\">Figure 5.3: Key mutational differences between Last Universal Common Ancestor and an amoeba-like primordial cell. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available<\/a>. Credit<strong>: <\/strong>Key differences between LUCA and a primordial cell original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Andrea J. Alveshere is a collective work under a <a class=\"rId21\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\">CC BY-NC-SA 4.0 License<\/a>. [Includes <a class=\"rId22\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Cladograma_dos_Dom%C3%ADnios_e_Reinos.png\">Cladograma dos Dominios e Reinos<\/a> by <a class=\"rId23\" href=\"https:\/\/commons.wikimedia.org\/wiki\/User:MarceloTeles\">MarceloTeles<\/a> (cropped, labels and colour changed), <a class=\"rId24\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/deed.en\">CC BY-SA 4.0<\/a><a class=\"rId25\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/deed.en\">; <\/a><a class=\"rId26\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Amoeba_proteus_TK-UT.svg\">Amoeba Proteus TK-UT<\/a> by <a class=\"rId27\" href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Nefronus\">Tom\u00e1\u0161 Kebert<\/a> and <a class=\"rId28\" href=\"https:\/\/www.umimeto.org\/\">umimeto.org<\/a> (cropped and colour changed), <a class=\"rId29\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/deed.en\">CC BY-SA 4.0<\/a>.]<\/figcaption><\/figure>\n<p class=\"import-Normal\">When we think of genetic mutation, we often first think of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1476\">deleterious mutations<\/a><\/strong>\u2014the ones associated with negative effects such as the beginnings of cancers or heritable disorders. The fact is, though, that every genetic adaptation that has helped our ancestors survive since the dawn of life is directly due to <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1478\">beneficial mutations<\/a><\/strong>\u2014changes in the DNA that provided some sort of advantage to a given population at a particular moment in time. For example, a beneficial mutation allowed chihuahuas and other tropical-adapted dog breeds to have much thinner fur coats than their cold-adapted cousins the northern wolves, malamutes, and huskies.<\/p>\n<figure style=\"width: 320px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image4-1-1.png\" alt=\"UV radiation damages nucleotides in DNA.\" width=\"320\" height=\"248\" \/><figcaption class=\"wp-caption-text\">Figure 5.4: A crosslinking mutation in which a UV photon induces a bond between two thymine bases. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available<\/a>. Credit<strong>: <\/strong><a class=\"rId31\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-3\/\">UV-induced Thymine dimer mutation (Figure 4.6)<\/a> original to <a class=\"rId32\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a class=\"rId33\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Every one of us has genetic mutations. Yes, even you. The DNA in some of your cells today differs from the original DNA that you inherited when you were a tiny, fertilized egg. Mutations occur all the time in the cells of our skin and other organs, due to chemical changes in the nucleotides. Exposure to the UV radiation in sunlight is one common cause of skin mutations. Interaction with UV light causes <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1480\"><strong>UV crosslinking<\/strong><\/a>, in which adjacent thymine bases bind with one another (Figure 5.4). Many of these mutations are detected and corrected by <strong>DNA repair mechanisms<\/strong>, enzymes that patrol and repair DNA in living cells, while other mutations may cause a new freckle or mole or, perhaps, an unusual hair to grow. For people with the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1484\">autosomal recessive<\/a><\/strong> disease <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1486\"><strong>xeroderma pigmentosum<\/strong><\/a>, these repair mechanisms do not function correctly, resulting in a host of problems especially related to sun exposure, including severe sunburns, dry skin, heavy freckling, and other pigment changes.<\/p>\n<p class=\"import-Normal\">Most of our mutations exist in <strong>somatic<\/strong> cells, which are the cells of our organs and other body tissues. Those will not be passed onto future generations and so will not affect the population over time. Only mutations that occur in the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_686\">gametes<\/a><\/strong>, the reproductive cells (i.e., the sperm or egg cells), will be passed onto future generations. When a new mutation pops up at random in a family lineage, it is known as a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1490\"><strong>spontaneous mutation<\/strong><\/a>. If the individual born with this spontaneous mutation passes it on to his offspring, those offspring receive an <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1492\">inherited mutation<\/a><\/strong>. Geneticists have identified many classes of mutations and the causes and effects of many of these.<\/p>\n<h4 class=\"import-Normal\"><em>Point Mutations<\/em><\/h4>\n<p class=\"import-Normal\">A <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1494\">point mutation<\/a><\/strong> is a single-letter (single-nucleotide) change in the genetic code resulting in the substitution of one nucleic acid base for a different one. As you learned in Chapter 4, the DNA code in each gene is translated through three-letter \u201cwords\u201d known as <strong>codons<\/strong>. So depending on how the point mutation changes the \u201cword,\u201d the effect it will have on the protein may be major or minor or may make no difference at all.<\/p>\n<p class=\"import-Normal\">If a mutation does not change the resulting protein, then it is called a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1496\">synonymous mutation<\/a><\/strong>. Synonymous mutations do involve a letter (nucleic acid) change, but that change results in a codon that codes for the same \u201cinstruction\u201d (the same amino acid or stop code) as the original codon. Mutations that do cause a change in the protein are known as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1498\"><strong>nonsynonymous mutations<\/strong>.<\/a> Nonsynonymous mutations may change the resulting protein\u2019s amino acid sequence by altering the DNA sequence that encodes the mRNA or by changing how the mRNA is spliced prior to translation (refer to Chapter 4 for more details).<\/p>\n<h4 class=\"import-Normal\"><em>Insertions and Deletions<\/em><\/h4>\n<p class=\"import-Normal\">In addition to point mutations, another class of mutations are <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1500\"><strong>insertions<\/strong><\/a> and <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1504\">deletions<\/a><\/strong>, or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1502\"><strong>indels<\/strong><\/a>, for short. As the name suggests, these involve the addition (insertion) or removal (deletion) of one or more coding sequence letters (nucleic acids). These typically first occur as an error in DNA replication, wherein one or more nucleotides are either duplicated or skipped in error. Entire codons or sets of codons may also be removed or added if the indel is a multiple of three nucleotides.<\/p>\n<p class=\"import-Normal\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1506\"><strong>Frameshift<\/strong> <strong>mutations<\/strong><\/a> are types of indels that involve the insertion or deletion of any number of nucleotides that is not a multiple of three (e.g., adding one or two extra letters to the code). Because these indels are not consistent with the codon numbering, they \u201cshift the reading frame,\u201d causing all the codons beyond the mutation to be misread. Like point mutations, small indels can also disrupt splice sites.<\/p>\n<p class=\"import-Normal\"><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1508\">Transposable elements<\/a><\/strong>, or <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1510\">transposons<\/a><\/strong>, are fragments of DNA that can \u201cjump\u201d around in the genome. There are two types of transposons: <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1512\">retrotransposons<\/a><\/strong> are transcribed from DNA into RNA and then \u201creverse transcribed,\u201d to insert the copied sequence into a new location in the DNA, and<strong> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1514\">DNA transposons<\/a><\/strong>, which do not involve RNA. DNA transposons are clipped out of the DNA sequence itself and inserted elsewhere in the genome. Because transposable elements insert themselves into existing DNA sequences, they are frequent gene disruptors. At certain times, and in certain species, it appears that transposons became very active, likely accelerating the mutation rate (and thus, the genetic variation) in those populations during the active periods.<\/p>\n<h4 class=\"import-Normal\"><em>Chromosomal Alterations <\/em><\/h4>\n<p class=\"import-Normal\">The final major category of genetic mutations are changes at the chromosome level: crossover events, nondisjunction events, and translocations. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1516\"><strong>Crossover events<\/strong> <\/a> occur when DNA is swapped between homologous chromosomes while they are paired up during meiosis I. Crossovers are thought to be so common that some DNA swapping may happen every time chromosomes go through meiosis I. Crossovers don\u2019t necessarily introduce new alleles into a population, but they do make it possible for new combinations of alleles to exist on a single chromosome that can be passed to future generations. This also enables new combinations of alleles to be found within siblings who share the same parents. Also, if the fragments that cross over don\u2019t break at exactly the same point, they can cause genes to be deleted from one of the homologous chromosomes and duplicated on the other.<\/p>\n<p class=\"import-Normal\"><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1518\">Nondisjunction events<\/a><\/strong> occur when the homologous chromosomes (in meiosis I) or sister chromatids (in meiosis II and mitosis) fail to separate after pairing. The result is that both chromosomes or chromatids end up in the same daughter cell, leaving the other daughter cell without any copy of that chromosome (Figure 5.5). Most nondisjunctions at the gamete level are fatal to the embryo. The most widely known exception is Trisomy 21, or Down syndrome, which results when an embryo inherits three copies of Chromosome 21: two from one parent (due to a nondisjunction event) and one from the other (Figure 5.6). <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1520\">Trisomies<\/a> <\/strong>(triple chromosome conditions) of Chromosomes 18 (Edwards syndrome) and 13 (Patau syndrome) are also known to result in live births, but the children usually have severe complications and rarely survive beyond the first year of life.<\/p>\n<figure style=\"width: 601px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image5.jpg\" alt=\"Egg cell undergoes normal meiosis and nondisjunction in meisosis 1.\" width=\"601\" height=\"391\" \/><figcaption class=\"wp-caption-text\">Figure 5.5: Illustration of an egg cell (oocyte) undergoing normal meiosis 1, resulting in a diploid daughter cell, compared to an egg cell undergoing nondisjunction during meiosis 1, resulting in a trisomy in the daughter cell. Credit: <a class=\"rId35\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Trisomy_due_to_nondisjunction_in_maternal_meiosis_1.png\">Trisomy due to nondisjunction in maternal meiosis 1<\/a> by Wpeissner has been modified (labels deleted by Katie Nelson) and is under a <a class=\"rId36\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\">CC BY-NC-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<figure style=\"width: 316px\" class=\"wp-caption alignright\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image6-1.jpg\" alt=\"A young woman in a blue polo shirt smiles at the camera.\" width=\"316\" height=\"364\" \/><figcaption class=\"wp-caption-text\">Figure 5.6: Amy Bockerstette, a competitive golfer and disabilities advocate, also has Down Syndrome. Credit: <a class=\"rId38\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Amy_Bockerstette_Headshot.jpg\">Amy Bockerstette Headshot<\/a> by Bucksgrandson is under a <a class=\"rId39\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Sex chromosome trisomies (XXX, XXY, XYY) and X chromosome <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1522\"><strong>monosomies<\/strong> <\/a>(inheritance of an X chromosome from one parent and no sex chromosome from the other) are also survivable and fairly common. The symptoms vary but often include atypical sexual characteristics, either at birth or at puberty, and often result in sterility. The X chromosome carries unique genes that are required for survival; therefore, Y chromosome monosomies are incompatible with life.<\/p>\n<p class=\"import-Normal\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1524\"><strong>Chromosomal translocations<\/strong><\/a> involve transfers of DNA between nonhomologous chromosomes. This may involve swapping large portions of two or more chromosomes. The exchanges of DNA may be balanced or unbalanced. In <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1526\"><strong>balanced translocations<\/strong><\/a>, the genes are swapped, but no genetic information is lost. In <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1528\">unbalanced translocations<\/a><\/strong>, there is an unequal exchange of genetic material, resulting in duplication or loss of genes. Translocations result in new chromosomal structures called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1530\"><strong>derivative chromosomes<\/strong><\/a>, because they are derived or created from two different chromosomes<em>. <\/em>Translocations are often found to be linked to cancers and can also cause infertility. Even if the translocations are balanced in the parent, the embryo often won\u2019t survive unless the baby inherits both of that parent\u2019s derivative chromosomes (to maintain the balance).<\/p>\n<h3 class=\"import-Normal\"><strong>Genetic Drift<\/strong><\/h3>\n<p class=\"import-Normal\">The second force of evolution is commonly known as genetic drift. This is an unfortunate misnomer, as this force actually involves the drifting of alleles, not genes. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1532\"><strong>Genetic <\/strong><strong>d<\/strong><strong>rift<\/strong><\/a> refers to <em>random<\/em> changes (\u201cdrift\u201d) in allele frequencies from one generation to the next. The genes are remaining constant within the population; it is only the alleles of the genes that are changing in frequency. The random nature of genetic drift is a crucial point to understand: it specifically occurs when none of the variant alleles confer an advantage.<\/p>\n<figure style=\"width: 368px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image7-2.png\" alt=\"A smooth cell has a gently curving exterior surface, and a ruffled cell has undulating surface.\" width=\"368\" height=\"215\" \/><figcaption class=\"wp-caption-text\">Figure 5.7: Smooth and ruffled amoeba-like cells. Credit: Smooth and ruffled amoeba-like cells original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Andrea J. Alveshere is a collective work under a <a class=\"rId41\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\">CC BY-NC-SA 4.0 License<\/a>. [Includes <a class=\"rId42\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Amoeba_proteus_TK-UT.svg\">Amoeba Proteus TK-UT<\/a> by <a class=\"rId43\" href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Nefronus\">Tom\u00e1\u0161 Kebert<\/a> and <a class=\"rId44\" href=\"https:\/\/www.umimeto.org\/\">umimeto.org<\/a> (modified), <a class=\"rId45\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/deed.en\">CC BY-SA 4.0<\/a>.]<\/figcaption><\/figure>\n<p class=\"import-Normal\">Let\u2019s imagine far back in time, again, to that ancient population of amoeba-like cells, subsisting and occasionally dividing, in the primordial sea. A mutation occurs in one of the cells that changes the texture of the cell membrane from a relatively smooth surface to a highly ruffled one (Figure 5.7). This has absolutely no effect on the cell\u2019s quality of life or ability to reproduce. In fact, eyes haven\u2019t evolved yet, so no one in the world at the time would even notice the difference. The cells in the population continue to divide, and the offspring of the ruffled cell inherit the ruffled membrane. The frequency (percentage) of the ruffled allele in the population, from one generation to the next, will depend entirely on how many offspring that first ruffled cell ends up having, and the random events that might make the ruffled alleles more common or more rare (such as population bottlenecks and founder effects, which are discussed below).<\/p>\n<h4 class=\"import-Normal\"><em>Sexual Reproduction and Random Inheritance<\/em><\/h4>\n<p class=\"import-Normal\">Tracking alleles gets a bit more complicated in our primordial cells when, after a number of generations, a series of mutations have created populations that reproduce sexually. These cells now must go through an extra round of cell division (meiosis) to create haploid gametes. The combination of two gametes is now required to produce each new diploid offspring.<\/p>\n<figure style=\"width: 262px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image8-1.png\" alt=\"A Punnett square with ruffled and smooth cells.\" width=\"262\" height=\"262\" \/><figcaption class=\"wp-caption-text\">Figure 5.8: A Punnett square demonstrating the sexual inheritance pattern of ruffled (dominant) and smooth amoeba-like primordial cells. Credit: Punnett square of primordial cells original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Andrea J. Alveshere is a collective work under a <a class=\"rId47\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\">CC BY-NC-SA 4.0 License<\/a>. [Includes <a class=\"rId48\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Amoeba_proteus_TK-UT.svg\">Amoeba Proteus TK-UT<\/a> by <a class=\"rId49\" href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Nefronus\">Tom\u00e1\u0161 Kebert<\/a> and <a class=\"rId50\" href=\"https:\/\/www.umimeto.org\/\">umimeto.org<\/a> (modified), <a class=\"rId51\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/deed.en\">CC BY-SA 4.0<\/a>; <a class=\"rId52\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Punnett_hetero_x_hetero.svg\">Punnett Hetero x Hetero<\/a> by <a class=\"rId53\" href=\"https:\/\/commons.wikimedia.org\/w\/index.php?title=User:Purpy_Pupple&amp;redirect=no\">Purpy Pupple<\/a> (modified), <a class=\"rId54\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/deed.en\">CC BY-SA 3.0<\/a>].<\/figcaption><\/figure>\n<p class=\"import-Normal\">In the earlier population, which reproduced via <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1534\">asexual reproduction<\/a><\/strong>, a cell either carried the smooth allele or the ruffled allele. With <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1536\">sexual reproduction<\/a><\/strong>, a cell inherits one allele from each parent, so there are homozygous cells that contain two smooth alleles, homozygous cells that contain two ruffled alleles, and heterozygous cells that contain one of each allele (Figure 5.8). If the new, ruffled allele happens to be dominant (and we\u2019ll imagine that it is), the heterozygotes will have ruffled cell <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1238\"><strong>phenotypes<\/strong><\/a> but also will have a 50\/50 chance of passing on a smooth allele to each offspring. As long as neither phenotype (ruffled nor smooth) provides any advantage over the other, the variation in the population from one generation to the next will remain completely random.<\/p>\n<p class=\"import-Normal\">In sexually reproducing populations (including humans and many other animals and plants in the world today), that 50\/50 chance of inheriting one or the other allele from each parent plays a major role in the random nature of genetic drift.<\/p>\n<h4 class=\"import-Normal\"><em>Population Bottlenecks <\/em><\/h4>\n<p class=\"import-Normal\">A <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1538\"><strong>population bottleneck<\/strong><\/a> occurs when the number of individuals in a population drops dramatically due to some random event. The most obvious, familiar examples are natural disasters. Tsunamis and hurricanes devastating island and coastal populations and forest fires and river floods wiping out populations in other areas are all too familiar. When a large portion of a population is randomly wiped out, the allele frequencies (i.e., the percentages of each allele) in the small population of survivors are often much different from the frequencies in the predisaster, or \u201cparent,\u201d population.<\/p>\n<p class=\"import-Normal\">If such an event happened to our primordial ocean cell population\u2014perhaps a volcanic fissure erupted in the ocean floor and only the cells that happened to be farthest from the spewing lava and boiling water survived\u2014we might end up, by random chance, with a surviving population that had mostly ruffled alleles, in contrast to the parent population, which had only a small percentage of ruffles (Figure 5.9).<\/p>\n<figure style=\"width: 665px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image9-2.png\" alt=\"Ruffled and smooth cells experience population bottleneck when a lava flow divides the populations.\" width=\"665\" height=\"332\" \/><figcaption class=\"wp-caption-text\">Figure 5.9: Illustration of a population of amoeba-like cells shifting from primarily smooth phenotypes (at left) to mostly ruffled phenotypes due to eruption of a volcanic fissure (at right) that exterminated the nearest cells. Credit: Population of amoeba-like cells and volcanic fissure original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Andrea J. Alveshere is a collective work under a <a class=\"rId56\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\">CC BY-NC-SA 4.0 License<\/a>. [Includes <a class=\"rId57\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Amoeba_proteus_TK-UT.svg\">Amoeba Proteus TK-UT<\/a> by <a class=\"rId58\" href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Nefronus\">Tom\u00e1\u0161 Kebert<\/a> and <a class=\"rId59\" href=\"https:\/\/www.umimeto.org\/\">umimeto.org<\/a> (modified), <a class=\"rId60\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/deed.en\">CC BY-SA 4.0<\/a>.]<\/figcaption><\/figure>\n<p class=\"import-Normal\">One of the most famous examples of a population bottleneck is the prehistoric disaster that led to the extinction of dinosaurs, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1540\"><strong>Cretaceous\u2013Paleogene <\/strong><strong>extinction<\/strong><\/a> event (often abbreviated K\u2013Pg; previously K-T). This occurred approximately 66 million years ago. Dinosaurs and all their neighbours were going about their ordinary routines when a massive asteroid zoomed in from space and crashed into what is now the Gulf of Mexico, creating an impact so enormous that populations within hundreds of miles of the crash site were likely immediately wiped out. The skies filled with dust and debris, causing temperatures to plummet worldwide. It\u2019s estimated that 75% of the world\u2019s species went extinct as a result of the impact and the deep freeze that followed (Jablonski and Chaloner 1994).<\/p>\n<figure style=\"width: 399px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image10-2.png\" alt=\" A rat-like creature sits atop a dinosaur, raising a fist in a victorious gesture.\" width=\"399\" height=\"323\" \/><figcaption class=\"wp-caption-text\">Figure 5.10: The Cretaceous\u2013Paleogene extinction event, which led to the fall of the dinosaurs and rise of the mammals. Credit: <a class=\"rId62\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-3\/\">The<\/a> <a class=\"rId64\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-3\/\">Cretaceous\u2013Paleogene extinction event (Figure 4.12)<\/a> original to <a class=\"rId65\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a class=\"rId66\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">The populations that emerged from the K-Pg extinction were markedly different from their pre-disaster communities. Surviving mammal populations expanded and diversified, and other new creatures appeared. The ecosystems of Earth were filled with new organisms and have never been the same (Figure 5.10).<\/p>\n<p class=\"import-Normal\">Much more recently in geological time, during the colonial period, many human populations experienced bottlenecks as a result of the fact that imperial powers were inclined to slaughter communities who were reluctant to give up their lands and resources. This effect was especially profound in the Americas, where Indigenous populations faced the compounded effects of brutal warfare, exposure to new bacteria and viruses (against which they had no immunity), and ultimately segregation on resource-starved reservations. The populations in Europe, Asia, and Africa had experienced regular gene flow during the 10,000-year period in which most kinds of livestock were being domesticated, giving them many generations of experience building up immunity against zoonotic diseases (those that can pass from animals to humans). In contrast, the residents of the Americas had been almost completely isolated during those millennia, so all these diseases swept through the Americas in rapid succession, creating a major loss of genetic diversity in the Indigenous American population. It is estimated that between 50% and 95% of the Indigenous American populations died during the first decades after European contact, around 500 years ago (Livi-Bacci 2006).<\/p>\n<p class=\"import-Normal\">An urgent health challenge facing humans today involves human-induced population bottlenecks that produce antibiotic-resistant bacteria. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1451\"><strong>Antibiotics<\/strong> <\/a>are medicines prescribed to treat bacterial infections. The typical prescription includes enough medicine for ten days. People often feel better much sooner than ten days and sometimes decide to quit taking the medicine ahead of schedule. This is often a big mistake. The antibiotics have quickly killed off a large percentage of the bacteria\u2014enough to reduce the symptoms and make you feel much better. However, this has created a bacterial population bottleneck. There are usually a small number of bacteria that survive those early days. If you take the medicine as prescribed for the full ten days, it\u2019s quite likely that there will be no bacterial survivors. If you quit early, though, the survivors\u2014who were the members of the original population who were most resistant to the antibiotic\u2014will begin to reproduce again. Soon the infection will be back, possibly worse than before, and now all of the bacteria are resistant to the antibiotic that you had been prescribed.<\/p>\n<p class=\"import-Normal\">Other activities that have contributed to the rise of antibiotic-resistant bacteria include the use of antibacterial cleaning products and the inappropriate use of antibiotics as a preventative measure in livestock or to treat infections that are viral instead of bacterial (viruses do not respond to antibiotics). In 2017, the World Health Organization published a list of twelve antibiotic-resistant pathogens that are considered top priority targets for the development of new antibiotics (World Health Organization 2017).<\/p>\n<div class=\"textbox shaded\" style=\"background: var(--lightblue)\">\n<h2>Dig Deeper: The North American Elephant Seal: Thriving Bottleneck Populations That Still Face Genetic Defects<\/h2>\n<p>In 1892, the Northern Elephant Seal underwent a severe population bottleneck caused by commercial hunting, reducing the species to an estimated 20 individuals at the time. This drastic decline led to a substantial loss of genetic diversity\u2013a common consequence of extreme population bottlenecks (Hoelzel Et al., 2024 &amp; Weber Et al., 2000). While the population has since recovered to over 200,000 individuals, its genetic variability remains significantly low. Analyses of genetic markers, including allozymes, mitochondrial DNA, and microsatellites, consistently reflect this reduced diversity (Hoelzel Et al., 2024). Comparative studies further underscore this loss by highlighting the higher genetic variation observed in the Southern Elephant Seal, which did not experience similar population constraints (2024).<\/p>\n<figure style=\"width: 386px\" class=\"wp-caption alignleft\"><img src=\"https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/4\/48\/Elephant_seals_at_Ano_Nuevo_%2891577%29.jpg\/250px-Elephant_seals_at_Ano_Nuevo_%2891577%29.jpg\" alt=\"File:Elephant seals at Ano Nuevo (91577).jpg\" width=\"386\" height=\"295\" \/><figcaption class=\"wp-caption-text\">Figure 5.11 A male northern elephant seal (Mirounga angustirostris) with two pups at Ano Nuevo State Park. Credit: Elephant seals at Ano Nuevo by Rhododendrites is under <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\" target=\"_blank\" rel=\"noopener\">Creative Commons Attribution-Share Alike 4.0<\/a>.<\/figcaption><\/figure>\n<p>In a 2024 study for Nature, Ecology, and Evolution, Hoelzel and colleagues sequenced 260 modern and 8 historical genomes of the northern elephant seal. This comparison revealed a decrease in average heterozygosity from 0.00142 before the bottleneck to 0.000176 in the contemporary population, confirming the decline in genetic variation (2024). Hoelzel\u2019s mitogenome tree further illustrates this loss, revealing only two significant lineages remaining post-bottleneck, with limited diversity within each. Among the issues of diversity, the population has shown an increased number of loss-of-function (LOF) alleles, suggesting that increased inbreeding has amplified the frequency of these detrimental alleles; this reduced genetic diversity negatively affects both male and female reproductive fitness. Females who practiced repetitive inbreeding had higher LOF alleles and subsequently weaned fewer pups per year over their lifetime, while male reproductive success was linked to specific LOF loci associated with sperm production (2024). Hoelzel uses the example of \u201cAlpha-Male M12\u201d\u2013known for low paternity success despite frequent copulations\u2013which was homozygous for non-functional versions of four out of five LOF loci related to sperm function (2024, p. 688). The species' mating system, characterized by extreme polygyny, further exacerbates the loss of genetic variation even with countless copulatory partners<\/p>\n<p>Prior research published in Current Biology presents an empirical genetic assessment of this population bottleneck, highlighting its long-term genetic consequences, particularly the loss of mitochondrial diversity (Weber et al., 2000). In this research, Weber and colleagues note that random lineage sampling during the bottleneck led to the persistence of specific genetic variants by chance rather than through natural selection (2000). This research emphasizes that the loss of diversity poses potential future genetic vulnerabilities for the seals, and that further studies are crucial for understanding the full scope of these impacts on the seals' overall fitness (2000). In 2024, the work led by Hoelzen and company provided the missing data that the previous study had left unanswered. Their previously explored findings indicate that, although the seals have recovered in numbers, their genetic resilience remains compromised, leaving the population more vulnerable to future environmental pressures, such as climate change or resource shortages (Hoelzel Et al., 2024). Ultimately, while the population's size remains stable, the genetic consequences of the bottleneck indicate that past stochastic events continue to influence the seals' long-term fitness and adaptability.<\/p>\n<p>This research indicates that the historical bottleneck continues to affect the seals' health and fitness, despite the population's recovery. Limited genetic diversity and the persistence of harmful alleles due to inbreeding have continued to handicap the species' ability to thrive in environmental challenges such as climate change and resource fluctuations (2024). This emphasizes the importance of incorporating genetic factors into conservation strategies, as populations that have rebounded may still harbour long-term genetic weaknesses. Moreover, the elephant seal\u2019s history serves as a powerful example of how human actions \u2014such as overhunting \u2014 can have long-lasting impacts on biodiversity, reinforcing the importance of understanding human-environment interactions in ecological and conservation contexts.<\/p>\n<\/div>\n<h4 class=\"import-Normal\"><em>Founder Effects<\/em><\/h4>\n<p class=\"import-Normal\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1452\"><strong>Founder effects<\/strong><\/a> occur when members of a population leave the main or \u201cparent\u201d group and form a new population that no longer interbreeds with the other members of the original group. Similar to survivors of a population bottleneck, the newly founded population often has allele frequencies that are different from the original group. Alleles that may have been relatively rare in the parent population can end up being very common due to the founder effect. Likewise, recessive traits that were seldom seen in the parent population may be seen frequently in the descendants of the offshoot population.<\/p>\n<p class=\"import-Normal\">One striking example of the founder effect was first noted in the Dominican Republic in the 1970s. During a several-year period, eighteen children who had been born with female genitalia and raised as girls suddenly grew penises at puberty. This culture tended to value sons over daughters, so these transitions were generally celebrated. They labeled the condition <em><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1453\">guevedoces<\/a><\/strong><\/em>, which translates to \u201cpenis at twelve,\u201d due to the average age at which this occurred. Scientists were fascinated by the phenomenon.<\/p>\n<p class=\"import-Normal\">Genetic and hormonal studies revealed that the condition, scientifically termed <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1454\">5-alpha reductase deficiency<\/a>,<\/strong> is an autosomal recessive syndrome that manifests when a child having both X and Y sex chromosomes inherits two nonfunctional (mutated) copies of the <em>SRD5A2 <\/em>gene (Imperato-McGinley &amp; Zhu 2002). These children develop testes internally, but the 5-alpha reductase 2 steroid, which is necessary for development of male genitals in babies, is not produced. In absence of this male hormone, the baby develops female-looking genitalia (in humans, \u201cfemale\u201d is the default infant body form, if the full set of the necessary male hormones are not produced). At puberty, however, a different set of male hormones are produced by other fully functional genes. These hormones complete the male genital development that did not happen in infancy. This condition became quite common in the Dominican Republic during the 1970s due to founder effect\u2014that is, the mutated <em>SRD5A2<\/em> gene happened to be much more common among the Dominican Republic\u2019s founding population than in the parent populations. (The Dominican population derives from a mixture of Indigenous Americans [Taino] peoples, West Africans, and Western Europeans.) Five-alpha reductase syndrome has since been observed in other small, isolated populations around the world.<\/p>\n<p class=\"import-Normal\">Founder effect is closely linked to the concept of inbreeding, which in population genetics does not necessarily mean breeding with immediate family relatives. Instead, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1455\"><strong>inbreeding<\/strong> <\/a> refers to the selection of mates exclusively from within a small, closed population\u2014that is, from a group with limited allelic variability. This can be observed in small, physically isolated populations but also can happen when cultural practices limit mates to a small group. As with the founder effect, inbreeding increases the risk of inheriting two copies of any nonfunctional (mutant) alleles.<\/p>\n<p class=\"import-Normal\">The Amish in the United States are a population that, due to their unique history and cultural practices, emerged from a small founding population and have tended to select mates from within their groups. The <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1456\">Old Order Amish<\/a><\/strong> population of Lancaster County, Pennsylvania, has approximately 50,000 current members, all of whom can trace their ancestry back to a group of approximately 80 individuals. This small founding population immigrated to the United States from Switzerland in the mid-1700s to escape religious persecution. Since the Amish keep to themselves and almost exclusively select mates from within their own communities, they have more recessive traits compared to their parent population.<\/p>\n<figure style=\"width: 441px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image11-1.jpg\" alt=\"One individual\u2019s hands with six fingers.\" width=\"441\" height=\"331\" \/><figcaption class=\"wp-caption-text\">Figure 5.12: A person displaying polydactyly. Credit: <a class=\"rId68\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:6_Finger.JPG\">6 Finger<\/a> by Wilhelmy is under a <a class=\"rId69\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">One of the genetic conditions that has been observed much more frequently in the Lancaster County Amish population is <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1457\">Ellis-van Creveld syndrome<\/a><\/strong>, which is an autosomal recessive disorder characterized by short stature (dwarfism), polydactyly (the development of more than five digits [fingers or toes] on the hands or feet], abnormal tooth development, and heart defects (Figure 5.12). Among the general world population, Ellis-van Creveld syndrome is estimated to affect approximately 1 in 60,000 individuals; among the Old Order Amish of Lancaster County, the rate is estimated to be as high as 1 in every 200 births (D\u2019Asdia Et al. 2013).<\/p>\n<p class=\"import-Normal\">One important insight that has come from the study of founder effects is that a limited gene pool carries a much higher risk for genetic diseases. Genetic diversity in a population greatly reduces these risks.<\/p>\n<h3 class=\"import-Normal\"><strong>Gene Flow<\/strong><\/h3>\n<p class=\"import-Normal\">The third force of evolution is traditionally called gene flow. As with genetic drift, this is a misnomer, because it refers to flowing alleles, not genes. (All members of the same species share the same genes; it is the alleles of those genes that may vary.) <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1459\"><strong>Gene <\/strong><strong>f<\/strong><strong>low<\/strong> <\/a> refers to the movement of alleles from one population to another. In most cases, gene flow can be considered synonymous with migration.<\/p>\n<p class=\"import-Normal\">Returning again to the example of our primordial cell population, let\u2019s imagine that, after the volcanic fissure opened up in the ocean floor, wiping out the majority of the parent population, two surviving populations developed in the waters on opposite sides of the fissure. Ultimately, the lava from the fissure cooled into a large island that continued to provide a physical barrier between the populations (Figure 5.13).<\/p>\n<figure style=\"width: 685px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image12-2.png\" alt=\"An illustration of gene flow.\" width=\"685\" height=\"342\" \/><figcaption class=\"wp-caption-text\">Figure 5.13: Smooth and predominantly ruffled amoeba-like populations separated by a volcanic eruption (at left) and an island (at right) with unidirectional gene flow moving from east to west with ocean currents. Credit: Population of amoeba-like cells separated by volcanic eruption original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Andrea J. Alveshere is a collective work under a <a class=\"rId74\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\">CC BY-NC-SA 4.0 License<\/a>. [Includes <a class=\"rId75\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Amoeba_proteus_TK-UT.svg\">Amoeba Proteus TK-UT<\/a> by <a class=\"rId76\" href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Nefronus\">Tom\u00e1\u0161 Kebert<\/a> and <a class=\"rId77\" href=\"https:\/\/www.umimeto.org\/\">umimeto.org<\/a> (modified), <a class=\"rId78\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/deed.en\">CC BY-SA 4.0<\/a>.]<\/figcaption><\/figure>\n<p class=\"import-Normal\">In the initial generations after the eruption, due to founder effect, isolation, and random inheritance (genetic drift), the population to the west of the islands contained a vast majority of the ruffled membrane alleles while the eastern population carried only the smooth alleles. Ocean currents in the area typically flowed from east to west, sometimes carrying cells (facilitating gene flow) from the eastern (smooth) population to the western (ruffled) population. Due to the ocean currents, it was almost impossible for any cells from the western population to be carried eastward. Thus, for inheritance purposes, the eastern (smooth) population remained isolated. In this case, the gene flow is unidirectional (going only in one direction) and unbalanced (only one population is receiving the new alleles).<\/p>\n<p class=\"import-Normal\">Among humans, gene flow is often described as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1460\"><strong>admixture<\/strong>.<\/a> In forensic cases, anthropologists and geneticists are often asked to estimate the ancestry of unidentified human remains to help determine whether they match any missing persons\u2019 reports. This is one of the most complicated tasks in these professions because, while \u201crace\u201d or \u201cancestry\u201d involves simple checkboxes on a missing person\u2019s form, among humans today there are no truly distinct genetic populations. All modern humans are members of the same fully breeding compatible species, and all human communities have experienced multiple episodes of gene flow (admixture), leading all humans today to be so genetically similar that we are all members of the same (and only surviving) human subspecies: <em>Homo sapiens sapiens.<\/em><\/p>\n<p class=\"import-Normal\">Gene flow between otherwise isolated nonhuman populations is often termed <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1461\">hybridization.<\/a>.<\/strong> One example of this involves the hybridization and spread of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1462\"><strong>Scutellata<\/strong><strong> honey bees<\/strong><\/a> (a.k.a. \u201ckiller bees\u201d) in the Americas. All honey bees worldwide are classified as <em>Apis mellifera.<\/em> Due to distinct adaptations to various environments around the world, there are 28 different subspecies of <em>Apis mellifera<\/em>.<\/p>\n<p class=\"import-Normal\">During the 1950s, a Brazilian biologist named Warwick E. Kerr experimented with hybridizing African and European subspecies of honey bees to try to develop a strain that was better suited to tropical environments than the European honey bees that had long been kept by North American beekeepers. Dr. Kerr was careful to contain the reproductive queens and drones from the African subspecies, but in 1957, a visiting beekeeper accidentally released 26 queen bees of the Scutellata subspecies (<em>Apis mellifera scutellata<\/em>) from southern Africa into the Brazilian countryside. The Scutellata bees quickly interbred with local European honey bee populations. The hybridized bees exhibited a much more aggressively defensive behaviour, fatally or near-fatally attacking many humans and livestock that ventured too close to their hives. The hybridized bees spread throughout South America and reached Mexico and California by 1985. By 1990, permanent colonies had been established in Texas, and by 1997, 90% of trapped bee swarms around Tucson, Arizona, were found to be Scutellata hybrids (Sanford 2006).<\/p>\n<p class=\"import-Normal\">Another example involves the introduction of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1463\"><strong>Harlequin ladybeetle<\/strong><\/a>, <em>Harmonia axyridis<\/em>, native to East Asia, to other parts of the world as a \u201cnatural\u201d form of pest control. Harlequin ladybeetles are natural predators of some of the aphids and other crop-pest insects. First introduced to North America in 1916, the \u201cbiocontrol\u201d strains of Harlequin ladybeetles were considered to be quite successful in reducing crop pests and saving farmers substantial amounts of money. After many decades of successful use in North America, biocontrol strains of Harlequin ladybeetles were also developed in Europe and South America in the 1980s.<\/p>\n<p class=\"import-Normal\">Over the seven decades of biocontrol use, the Harlequin ladybeetle had never shown any potential for development of wild colonies outside of its native habitat in China and Japan. New generations of beetles always had to be reared in the lab. That all changed in 1988, when a wild colony took root near New Orleans, Louisiana. Either through admixture with a native ladybeetle strain, or due to a spontaneous mutation, a new allele was clearly introduced into this population that suddenly enabled them to survive and reproduce in a wide range of environments. This population spread rapidly across the Americas and had reached Africa by 2004.<\/p>\n<p class=\"import-Normal\">In Europe, the invasive, North American strain of Harlequin ladybeetle admixed with the European strain (Figure 5.14), causing a population explosion (Lombaert Et al. 2010). Even strains specifically developed to be flightless (to curtail the spreading) produced flighted offspring after admixture with members of the North American population (Facon Et al. 2011). The fast-spreading, invasive strain has quickly become a disaster, out-competing native ladybeetle populations (some to the point of extinction), causing home infestations, decimating fruit crops, and contaminating many batches of wine with their bitter flavour after being inadvertently harvested with the grapes (Pickering Et al. 2004).<\/p>\n<figure style=\"width: 583px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image13-2.png\" alt=\"One gray ladybug is migrating to the group of white ladybugs.\" width=\"583\" height=\"219\" \/><figcaption class=\"wp-caption-text\">Figure 5.14: Gene flow between two populations of ladybeetles (ladybugs). Credit: <a class=\"rId80\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-3\/\">Ladybug Gene Flow (Figure 4.14)<\/a> original to <a class=\"rId81\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a class=\"rId82\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<h3 class=\"import-Normal\"><strong>Natural Selection<\/strong><\/h3>\n<p class=\"import-Normal\">The final force of evolution is natural selection. This is the evolutionary process that Charles Darwin first brought to light, and it is what the general public typically evokes when considering the process of evolution. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1465\"><strong>Natural <\/strong><strong>s<\/strong><strong>election<\/strong><\/a> occurs when certain phenotypes confer an advantage or disadvantage in survival and\/or reproductive success. The alleles associated with those phenotypes will change in frequency over time due to this selective pressure. It\u2019s also important to note that the advantageous allele may change over time (with environmental changes) and that an allele that had previously been benign may become advantageous or detrimental. Of course, dominant, recessive, and codominant traits will be selected upon a bit differently from one another. Because natural selection acts on phenotypes rather than the alleles themselves, deleterious (disadvantageous) alleles can be retained by heterozygotes without any negative effects.<\/p>\n<p class=\"import-Normal\">In the case of our primordial ocean cells, up until now, the texture of their cell membranes has been benign. The frequencies of smooth to ruffled alleles, and smooth to ruffled phenotypes, has changed over time, due to genetic drift and gene flow. Let\u2019s now imagine that the Earth\u2019s climate has cooled to a point that the waters frequently become too cold for survival of the tiny bacteria that are the dietary staples of our smooth and ruffled cell populations. The way amoeba-like cells \u201ceat\u201d is to stretch out the cell membrane, almost like an arm, to encapsulate, then ingest, the tiny bacteria. When the temperatures plummet, the tiny bacteria populations plummet with them. Larger bacteria, however, are better able to withstand the temperature change.<\/p>\n<p class=\"import-Normal\">The smooth cells were well-adapted to ingesting tiny bacteria but poorly suited to encapsulating the larger bacteria. The cells with the ruffled membranes, however, are easily able to extend their ruffles to encapsulate the larger bacteria. They also find themselves able to stretch their entire membrane to a much larger size than their smooth-surfaced neighbours, allowing them to ingest more bacteria at a given time and to go for longer periods between feedings (Figure 5.15).<\/p>\n<figure style=\"width: 528px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image14-2.png\" alt=\"Smooth and ruffled cells feeding on large and small bacteria.\" width=\"528\" height=\"307\" \/><figcaption class=\"wp-caption-text\">Figure 5.15: Smooth and ruffled cells feeding. Credit: Smooth and ruffled cells feeding original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Andrea J. Alveshere is a collective work under a <a class=\"rId84\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\">CC BY-NC-SA 4.0 License<\/a>. [Includes <a class=\"rId85\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Cladograma_dos_Dom%C3%ADnios_e_Reinos.png\">Cladograma dos Dominios e Reinos<\/a> by <a class=\"rId86\" href=\"https:\/\/commons.wikimedia.org\/wiki\/User:MarceloTeles\">MarceloTeles<\/a> (modified), <a class=\"rId87\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/deed.en\">CC BY-SA 4.0<\/a><a class=\"rId88\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/deed.en\">; <\/a><a class=\"rId89\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Amoeba_proteus_TK-UT.svg\">Amoeba Proteus TK-UT<\/a> by <a class=\"rId90\" href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Nefronus\">Tom\u00e1\u0161 Kebert<\/a> and <a class=\"rId91\" href=\"https:\/\/www.umimeto.org\/\">umimeto.org<\/a> (modified), <a class=\"rId92\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/deed.en\">CC BY-SA 4.0<\/a>.]<\/figcaption><\/figure>\n<p class=\"import-Normal\">The smooth and ruffled traits, which had previously offered no advantage or disadvantage while food was plentiful, now are subject to natural selection. During the cold snaps, at least, the ruffled cells have a definite advantage. We can imagine that the western population that has mostly ruffled alleles will continue to do well, while the eastern population is at risk of dying out if the smaller bacteria remain scarce and no ruffled alleles are introduced.<\/p>\n<p class=\"import-Normal\">A classic example of natural selection involves the study of an insect called the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1466\">peppered moth<\/a><\/strong> (<em>Biston betularia<\/em>) in England during the Industrial Revolution in the 1800s. Prior to the Industrial Revolution, the peppered moth population was predominantly light in colour, with dark (pepper-like) speckles on the wings. The \u201cpeppered\u201d colouration was very similar to the appearance of the bark and lichens that grew on the local trees (Figure 5.16). This helped to camouflage the moths as they rested on a tree, making it harder for moth-eating birds to find and snack on them. There was another phenotype that popped up occasionally in the population. These individuals were heterozygotes that carried an overactive, dominant pigment allele, producing a solid black colouration. As you can imagine, the black moths were much easier for birds to spot, making this phenotype a real disadvantage.<\/p>\n<p class=\"import-Normal\">The situation changed, however, as the Industrial Revolution took off. Large factories began spewing vast amounts of coal smoke into the air, blanketing the countryside, including the lichens and trees, in black soot. Suddenly, it was the light-coloured moths that were easy for birds to spot and the black moths that held the advantage. The frequency of the dark pigment allele rose dramatically. By 1895, the black moth phenotype accounted for 98% of observed moths (Grant 1999).<\/p>\n<figure style=\"width: 476px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image15-2.png\" alt=\"An illustration of natural selection.\" width=\"476\" height=\"531\" \/><figcaption class=\"wp-caption-text\">Figure 5.16: Dark and light peppered moth variants and their relative camouflage abilities on clean (top) and sooty (bottom) trees. Credit: <a class=\"rId94\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Peppered_moths_c2.jpg\">Peppered moths c2<\/a> by Khaydock is under a <a class=\"rId95\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Thanks to new environmental regulations in the 1960s, the air pollution in England began to taper off. As the soot levels decreased, returning the trees to their former, lighter colour, this provided the perfect opportunity to study how the peppered moth population would respond. Repeated follow-up studies documented the gradual rise in the frequency of the lighter-coloured phenotype. By 2003, the maximum frequency of the dark phenotype was 50% and in most parts of England had decreased to less than 10% (Cook, 2003).<\/p>\n<h4 class=\"import-Normal\"><em>Directional, Balancing\/Stabilizing, and Disruptive\/Diversifying Selection<\/em><\/h4>\n<p class=\"import-Normal\">Natural selection can be classified as directional, balancing\/stabilizing, or disruptive\/diversifying, depending on how the pressure is applied to the population (Figure 5.17).<\/p>\n<figure style=\"width: 465px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image16-2.png\" alt=\"Three types of selection; balancing, directional and disruptive\/diversifying\" width=\"465\" height=\"574\" \/><figcaption class=\"wp-caption-text\">Figure 5.17: Lines depict the affects of (a) Balancing\/Stabilizing, (b) Directional, and (c) Disruptive\/Diversifying selection on populations. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available<\/a>. Credit: <a class=\"rId97\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Figure_19_03_01.png\">Biology (ID: 185cbf87-c72e-48f5-b51e-f14f21b5eabd@9.17)<\/a> by <a class=\"rId98\" href=\"https:\/\/cnx.org\/\">CNX OpenStax<\/a> is used under a <a class=\"rId99\" href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/deed.en\">CC BY 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Both of the above examples of natural selection involve <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1467\">directional selection<\/a><\/strong>: the environmental pressures favour one phenotype over the other and cause the frequencies of the associated advantageous alleles (ruffled membranes, dark pigment) to gradually increase. In the case of the peppered moths, the direction shifted three times: first, it was selecting for lighter pigment; then, with the increase in pollution, the pressure switched to selection for darker pigment; finally, with reduction of the pollution, the selection pressure shifted back again to favouring light-coloured moths.<\/p>\n<p class=\"import-Normal\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1468\"><strong>Balancing selection<\/strong><\/a> (a.k.a. stabilizing selection) occurs when selection works against the extremes of a trait and favours the intermediate phenotype. For example, humans maintain an average birth weight that balances the need for babies to be small enough not to cause complications during pregnancy and childbirth but big enough to maintain a safe body temperature after they are born. Another example of balancing selection is found in the genetic disorder called sickle cell anemia (see \u201cSpecial Topic: Sickle Cell Anemia\u201d).<\/p>\n<p class=\"import-Normal\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1469\"><strong>Disruptive selection<\/strong><\/a> (a.k.a. diversifying selection), the opposite of balancing selection, occurs when both extremes of a trait are advantageous. Since individuals with traits in the mid-range are selected against, disruptive selection can eventually lead to the population evolving into two separate species. Darwin believed that the many species of finches (small birds) found in the remote Galapagos Islands provided a clear example of disruptive selection leading to speciation. He observed that seed-eating finches either had large beaks, capable of eating very large seeds, or small beaks, capable of retrieving tiny seeds. The islands did not have many plants that produced medium-size seeds. Thus, birds with medium-size beaks would have trouble eating the very large seeds and would also have been inefficient at picking up the tiny seeds. Over time, Darwin surmised, this pressure against mid-size beaks may have led the population to divide into two separate species.<\/p>\n<h4 class=\"import-Normal\"><em>Sexual Selection<\/em><\/h4>\n<p class=\"import-Normal\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1470\"><strong>Sexual <\/strong><strong>s<\/strong><strong>election<\/strong><\/a> is an aspect of natural selection in which the selective pressure specifically affects reproductive success (the ability to successfully breed and raise offspring) rather than survival. Sexual selection favours traits that will attract a mate. Sometimes these sexually appealing traits even carry greater risks in terms of survival.<\/p>\n<figure style=\"width: 354px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image17-2.png\" alt=\"A fox chases a peacock fleeing; a peacock displays his feathers to a peahen.\" width=\"354\" height=\"413\" \/><figcaption class=\"wp-caption-text\">Figure 5.18: Showy peacock tail disadvantages (becoming easier prey) and advantages (impressing peahens). Credit: <a class=\"rId101\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-3\/\">Peacock tail advantage and disadvantages (Figure 4.18)<\/a> original to <a class=\"rId102\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a class=\"rId103\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.License.<\/figcaption><\/figure>\n<p class=\"import-Normal\">A classic example of sexual selection involves the brightly coloured feathers of the peacock. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1471\"><strong>peacock<\/strong><\/a> is the male sex of the peafowl genera <em>Pavo<\/em> and <em>Afropavo. <\/em>During mating season, peacocks will fan their colourful tails wide and strut in front of the peahens in a grand display. The peahens will carefully observe these displays and will elect to mate with the male that they find the most appealing. Many studies have found that peahens prefer the males with the fullest, most colourful tails. While these large, showy tails provide a reproductive advantage, they can be a real burden in terms of escaping predators. The bright colours and patterns as well as the large size of the peacock tail make it difficult to hide. Once predators spot them, peacocks also struggle to fly away, with the heavy tail trailing behind and weighing them down (Figure 5.18). Some researchers have argued that the increased risk is part of the appeal for the peahens: only an especially strong, alert, and healthy peacock would be able to avoid predators while sporting such a spectacular tail.<\/p>\n<\/div>\n<p>It\u2019s important to keep in mind that sexual selection relies on the trait being present throughout mating years. Reflecting on the NF1 genetic disorder (see \u201cSpecial Topic: Neurofibromatosis Type 1 [NF1]\u201d), given how disfiguring the symptoms can become, some might find it surprising that half of the babies born with NF1 inherited it from a parent. Given that the disorder is autosomal dominant and fully penetrant (meaning it has no unaffected carriers), it may seem surprising that sexual selection doesn\u2019t exert more pressure against the mutated alleles. One important factor is that, while the neurofibromas typically begin to appear during puberty, they usually emerge only a few at a time and may grow very slowly. Many NF1 patients don\u2019t experience the more severe or disfiguring symptoms until later in life, long after they have started families of their own.<\/p>\n<p class=\"import-Normal\">Some researchers prefer to classify sexual selection separately, as a fifth force of evolution. The traits that underpin mate selection are entirely natural, of course. Research has shown that subtle traits, such as the type of pheromones (hormonal odors related to immune system alleles) someone emits and how those are perceived by the immune system genotype of the \u201csniffer,\u201d may play crucial and subconscious roles in whether we find someone attractive or not (Chaix, Cao, &amp; Donnelly 2008).<\/p>\n<div class=\"textbox\">\n<h2><\/h2>\n<h2 class=\"import-Normal\">Special Topic: Neurofibromatosis Type 1 (NF1)<\/h2>\n<p class=\"import-Normal\"><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1476\">Neurofibromatosis Type 1<\/a><\/strong>, also known as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1477\"><strong>NF1<\/strong><\/a>, is a genetic disorder that illustrates how a mutation in a single gene can affect multiple systems in the body. Surprisingly common, more people have NF1 than cystic fibrosis and muscular dystrophy combined. Even more surprising, given how common it is, is how few people have heard of it. One in every 3,000 babies is born with NF1, and this holds true for all populations worldwide (Riccardi 1992). This means that, for every 3,000 people in your community, there is likely at least one person living with this disorder. NF1 is an <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1478\">autosomal dominant<\/a> <\/strong>condition, which means that everyone born with a mutation in the gene, whether inherited or spontaneous, has a 50\/50 chance of passing it on to each of their own children.<\/p>\n<p class=\"import-Normal\">The NF1 disorder results from mutation of the <em>NF1<\/em> gene on Chromosome 17. Almost any mutation that affects the sequence of the gene\u2019s protein product, neurofibromin, will cause the disorder. Studies of individuals with NF1 have identified over 3,000 different mutations of all kinds (including point mutations, small and large indels, and translocations). The <em>NF1 <\/em>gene is one of the largest known genes, containing at least 60 <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_724\">exons<\/a><\/strong> (protein-encoding sequences) in a span of about 300,000 nucleotides.<\/p>\n<p class=\"import-Normal\">We know that neurofibromin plays an important role in preventing tumor growth because one of the most common symptoms of the NF1 disorder is the growth of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1479\">benign<\/a> <\/strong>(noncancerous) tumors, called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1486\">neurofibromas<\/a><\/strong>. Neurofibromas sprout from nerve sheaths\u2014the tissues that encase our nerves\u2014throughout the body, usually beginning around puberty. There is no way to predict where the tumors will occur, or when or how quickly they will grow, although only about 15% turn <strong>malignant<\/strong> (cancerous). The two types of neurofibromas that are typically most visible are <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1480\"><strong>cutaneous neurofibromas<\/strong><\/a>, which are spherical bumps on, or just under, the surface of the skin (Figure 5.19), and <strong>plexiform neurofibromas<\/strong><em>, <\/em>growths involving whole branches of nerves, often giving the appearance that the surface of the skin is \u201cmelting\u201d (Figure 5.20).<\/p>\n<figure id=\"attachment_131-3\" aria-describedby=\"caption-attachment-131-3\" style=\"width: 510px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-129\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/4.18.jpg\" alt=\"A woman has dozens of round, skin-colored tumors visible on her face, neck, and hand.\" width=\"510\" height=\"340\" \/><figcaption id=\"caption-attachment-131-3\" class=\"wp-caption-text\">Figure 5.19: A woman with many cutaneous neurofibromas, a common symptom of Neurofibromatosis Type 1. Credit: <a class=\"rId105\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-3\/\">Woman with cutaneous neurofibromas (symptom of NF1)<\/a> by <a class=\"rId106\" href=\"https:\/\/positiveexposure.org\/about-the-program-2\/rick-guidotti\/\">Rick Guidotti of Positive Exposure<\/a> is used with permission and is available here under a <a class=\"rId107\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<figure id=\"attachment_131-4\" aria-describedby=\"caption-attachment-131-4\" style=\"width: 1900px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-130 size-full\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/4.19.jpg\" alt=\"An adult with large plexiform neurofibromas covering his face, none are on the child.\" width=\"1900\" height=\"700\" \/><figcaption id=\"caption-attachment-131-4\" class=\"wp-caption-text\">Figure 5.20: Photo on the left is of a man with large plexiform neurofibroma, another symptom of Neurofibromatosis Type 1. Photo on the right is a childhood photo of the same man, illustrating the progressive nature of the NF1 disorder. Credit: <a class=\"rId110\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-3\/\">Man with plexiform neurofibroma (symptom of NF1)<\/a> from Ashok Shrestha is used by permission and available here under a <a class=\"rId111\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>. <a class=\"rId112\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-3\/\">Childhood photo of the same man with NF1 disorder<\/a> from Ashok Shrestha is used by permission and available here under a <a class=\"rId113\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Unfortunately, there is currently no cure for NF1. Surgical removal of neurofibromas risks paralysis, due to the high potential for nerve damage, and often results in the tumors growing back even more vigorously. This means that patients are often forced to live with disfiguring and often painful neurofibromas. People who are not familiar with NF1 often mistake neurofibromas for something contagious. This makes it especially hard for people living with NF1 to get jobs working with the public or even to enjoy spending time away from home. Raising public awareness about NF1 and its symptoms can be a great help in improving the quality of life for people living with this condition.<\/p>\n<figure style=\"width: 311px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image21-2.png\" alt=\"A child with darker oval birthmarks scattered across his torso and arms.\" width=\"311\" height=\"415\" \/><figcaption class=\"wp-caption-text\">Figure 5.21: Image of a child with caf\u00e9-au-lait macules (birthmarks) typical of the earliest symptoms of NF1. Credit: <a class=\"rId115\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-3\/\">Child with caf\u00e9-au-lait macules (birthmarks) typical of the earliest symptoms of NF1<\/a> by Andrea J. Alveshere is under a <a class=\"rId116\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">One of the first symptoms of NF1 in a small child is usually the appearance of <strong>caf\u00e9-au-lait spots<\/strong>, or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1490\"><strong>CALS<\/strong><\/a>, which are flat, brown birthmark-like spots on the skin (Figure 5.21). CALS are often light brown, similar to the colour of coffee with cream, which is the reason for the name, although the shade of the pigment depends on a person\u2019s overall complexion. Some babies are born with CALS, but for others the spots appear within the first few years of life. Having six or more CALS larger than five millimetres (mm) across is a strong indicator that a child may have NF1.<\/p>\n<p class=\"import-Normal\">Other common symptoms include the following: gliomas (tumors) of the optic nerve, which can cause vision loss; thinning of bones and failure to heal if they break (often requiring amputation); low muscle tone (poor muscle development, often delaying milestones such as sitting up, crawling, and walking); hearing loss, due to neurofibromas on auditory nerves; and learning disabilities, especially those involving spatial reasoning. Approximately 50% of people with NF1 have some type of speech and\/or learning disability and often benefit greatly from early intervention services. Generalized developmental disability, however, is not common with NF1, so most people with NF1 live independently as adults. Many people with NF1 live full and successful lives, as long as their symptoms can be managed.<\/p>\n<p class=\"import-Normal\">Based on the wide variety of symptoms, it\u2019s clear that the neurofibromin protein plays important roles in many biochemical pathways. While everyone who has NF1 will exhibit some symptoms during their lifetime, there is a great deal of variation in the types and severity of symptoms, even between individuals from the same family who share the exact same NF1 mutation. It seems crazy that a gene with so many important functions would be so susceptible to mutation. Part of this undoubtedly has to do with its massive size\u2014a gene with 300,000 nucleotides has ten times more nucleotides available for mutation than does a gene of 30,000 bases. This also suggests that the mutability of this gene might provide some benefits, which is a possibility that we will revisit later in this chapter.<\/p>\n<\/div>\n<div class=\"textbox\">\n<h2 class=\"import-Normal\">Special Topic: Sickle Cell Anemia<\/h2>\n<p class=\"import-Normal\"><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1492\">Sickle cell anemia<\/a><\/strong> is an autosomal recessive genetic disorder that affects millions of people worldwide. It is most common in Africa, countries around the Mediterranean Sea, and eastward as far as India. Populations in the Americas that have high percentages of ancestors from these regions also have high rates of sickle cell anemia. In the United States, it\u2019s estimated that 72,000 people live with the disease, with one in approximately 1,200 Hispanic-American babies and one in every 500 African-American babies inheriting the condition (World Health Organization 1996).<\/p>\n<figure style=\"width: 344px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image22-2.png\" alt=\"Round and sickle cells.\" width=\"344\" height=\"258\" \/><figcaption class=\"wp-caption-text\">Figure 5.22: Sickle cell anemia. Arrows indicate (a) sickled and (b) normal red blood cells. Credit: <a class=\"rId118\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Sickle-cell_smear_2015-09-10.jpg\">Sickle-cell smear 2015-09-10<\/a> by Paulo Henrique Orlandi Mourao has been modified (contrast modified and labels added) and is under a <a class=\"rId119\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\">CC BY-NC-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Sickle cell anemia affects the hemoglobin protein in red blood cells. Normal red blood cells are somewhat doughnut-shaped\u2014round with a depression on both sides of the middle. They carry oxygen around the bloodstream to cells throughout the body. Red blood cells produced by the mutated form of the gene take on a stiff, sickle-like crescent shape when stressed by low oxygen or dehydration (Figure 5.22). Because of their elongated shape and the fact that they are stiff rather than flexible, they tend to form clumps in the blood vessels, inhibiting blood flow to adjacent areas of the body. This causes episodes of extreme pain and can cause serious problems in the oxygen-deprived tissues. The sickle cells also break down much more quickly than normal cells, often lasting only 20 days rather than the 120 days of normal cells. This causes an overall shortage of blood cells in the sickle cell patient, resulting in low iron (anemia) and problems associated with it such as extreme fatigue, shortness of breath, and hindrances to children\u2019s growth and development.<\/p>\n<p class=\"import-Normal\">The devastating effects of sickle cell anemia made its high frequency a pressing mystery. Why would an allele that is so deleterious in its homozygous form be maintained in a population at levels as high as the one in twelve African Americans estimated to carry at least one copy of the allele? The answer turned out to be one of the most interesting cases of balancing selection in the history of genetic study.<\/p>\n<p class=\"import-Normal\">While looking for an explanation, scientists noticed that the countries with high rates of sickle cell disease also shared a high risk for another disease called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1493\"><strong>malaria<\/strong><\/a>, which is caused by infection of the blood by a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1494\"><strong><em>Plasmodium<\/em><\/strong><\/a> parasite. These parasites are carried by mosquitoes and enter the human bloodstream via a mosquito bite. Once infected, the person will experience flu-like symptoms that, if untreated, can often lead to death. Researchers discovered that many people living in these regions seemed to have a natural resistance to malaria. Further study revealed that people who carry the sickle cell allele are far less likely to experience a severe case of malaria. This would not be enough of a benefit to make the allele advantageous for the sickle cell homozygotes, who face shortened life spans due to sickle cell anemia. The real benefit of the sickle cell allele goes to the heterozygotes.<\/p>\n<p class=\"import-Normal\">People who are heterozygous for sickle cell carry one normal allele, which produces the normal, round, red blood cells, and one sickle cell allele, which produces the sickle-shaped red blood cells. Thus, they have both the sickle and round blood cell types in their bloodstream. They produce enough of the round red blood cells to avoid the symptoms of sickle cell anemia, but they have enough sickle cells to provide protection from malaria.<\/p>\n<p class=\"import-Normal\">When the <em>Plasmodium <\/em>parasites infect an individual, they begin to multiply in the liver, but then must infect the red blood cells to complete their reproductive cycle. When the parasites enter sickle-type cells, the cells respond by taking on the sickle shape. This prevents the parasite from circulating through the bloodstream and completing its life cycle, greatly inhibiting the severity of the infection in the sickle cell heterozygotes compared to non\u2013-sickle cell homozygotes. See Chapter 14 for more discussion of sickle cell anemia.<\/p>\n<\/div>\n<div class=\"textbox\">\n<h2 class=\"import-Normal\">Special Topic: The Real Primordial Cells\u2014<em>Dictyostelium Discoideum<\/em><\/h2>\n<p class=\"import-Normal\">The amoeba-like primordial cells that were used as recurring examples throughout this chapter are inspired by actual research that is truly fascinating. In 2015, Gareth Bloomfield and colleagues reported on their genomic study of the social amoeba <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1496\"><strong><em>Dictyostelium discoideum<\/em><\/strong> <\/a>(a.k.a. \u201cslime molds,\u201d although technically they are amoebae, not molds). Strains of these amoebae have been grown in research laboratories for many decades and are useful in studying the mechanisms that amoeboid single-celled organisms use to ingest food and liquid. For simplification of our examples in this chapter, our amoeba-like cells remained ocean dwellers. Wild <em>Dictyostelium discoideum<\/em>, however, live in soil and feed on soil bacteria by growing ruffles in their membranes that reach out to encapsulate the bacterial cell. Laboratory strains, however, are typically raised on liquid media (agar) in Petri dishes, which is not suitable for the wild-type amoebae. It was widely known that the laboratory strains must have developed mutations in one or more genes to allow them to ingest the larger nutrient particles in the agar and larger volumes of liquid, but the genes involved were not known.<\/p>\n<p class=\"import-Normal\">Bloomfield and colleagues performed genomic testing on both the wild and the laboratory strains of <em>Dictyostelium discoideum. <\/em>Their discovery was astounding: every one of the laboratory strains carried a mutation in the <em>NF1 <\/em>gene, the very same gene associated with Neurofibromatosis Type 1 (NF1) in humans. The antiquity of this massive, easily mutated gene is incredible. It originated in an ancestor common to both humans and these amoebae, and it has been retained in both lineages ever since. As seen in <em>Dictyostelium discoideum<\/em>, breaking the gene can be advantageous. Without a functioning copy of the neurofibromin protein, the cell membrane is able to form much-larger feeding structures, allowing the <em>NF1 <\/em>mutants to ingest larger particles and larger volumes of liquid. For these amoebae, this may provide dietary flexibility that functions somewhat like an insurance policy for times when the food supply is limited.<\/p>\n<p class=\"import-Normal\"><em>Dictyostelium discoideum <\/em>are also interesting in that they typically reproduce asexually, but under certain conditions, one cell will convert into a \u201cgiant\u201d cell, which encapsulates surrounding cells, transforming into one of three sexes. This cell will undergo meiosis, producing gametes that must combine with one of the other two sexes to produce viable offspring. This ability for sexual reproduction may be what allows <em>Dictyostelium discoideum<\/em> to benefit from the advantages of <em>NF1<\/em> mutation, while also being able to restore the wild type <em>NF1<\/em> gene in future generations.<\/p>\n<p class=\"import-Normal\">What does this mean for humans living with NF1? Well, understanding the role of the neurofibromin protein in the membranes of simple organisms like <em>Dictyostelium discoideum<\/em> may help us to better understand how it functions and malfunctions in the sheaths of human neurons. It\u2019s also possible that the mutability of the NF1 gene confers certain advantages to humans as well. Alleles of the NF1 gene have been found to reduce one\u2019s risk for alcoholism (Repunte-Canonigo Vez Et al. 2015), opiate addiction (Sanna Et al. 2002), Type 2 diabetes (Martins Et al. 2016), and hypomusicality (a lower-than-average musical aptitude; Cota Et al. 2018). This research is ongoing and will be exciting to follow in the coming years.<\/p>\n<\/div>\n<h2 class=\"__UNKNOWN__\">Studying Evolution in Action<\/h2>\n<div class=\"__UNKNOWN__\">\n<h3 class=\"import-Normal\"><strong>The Hardy-Weinberg Equilibrium <\/strong><\/h3>\n<p class=\"import-Normal\">This chapter has introduced you to the forces of evolution, the mechanisms by which evolution occurs. How do we detect and study evolution, though, in real time, as it happens? One tool we use is the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1497\"><strong>Hardy-<\/strong><strong>Weinberg<\/strong><strong> Equilibrium<\/strong><\/a>: a mathematical formula that allows estimation of the number and distribution of dominant and recessive alleles in a population. This aids in determining whether allele frequencies are changing and, if so, how quickly over time, and in favour of which allele? It\u2019s important to note that the Hardy-Weinberg formula only gives us an estimate based on the data for a snapshot in time. We will have to calculate it again later, after various intervals, to determine if our population is evolving and in what way the allele frequencies are changing.<\/p>\n<h3 class=\"import-Normal\">Calculating the Hardy-Weinberg Equilibrium<\/h3>\n<p class=\"import-Normal\">In the Hardy-Weinberg formula, <em>p <\/em>represents the frequency of the dominant allele, and <em>q<\/em> represents the frequency of the recessive allele. Remember, an allele\u2019s frequency is the proportion, or percentage, of that allele in the population. For the purposes of Hardy-Weinberg, we give the allele percentages as decimal numbers (e.g., 42% = 0.42), with the entire population (100% of alleles) equaling 1. If we can figure out the frequency of one of the alleles in the population, then it is simple to calculate the other. Simply subtract the known frequency from 1 (the entire population): 1<em> \u2013 p = q<\/em> and 1<em> \u2013 q = p<\/em>.<\/p>\n<p class=\"import-Normal\">The Hardy-Weinberg formula is <em>p<\/em><sup><em>2<\/em><\/sup><em> + 2pq + q<\/em><sup><em>2<\/em><\/sup>, where:<\/p>\n<p class=\"import-Normal\" style=\"padding-left: 40px\"><em>p<\/em><sup><em>2<\/em><\/sup> represents the frequency of the homozygous dominant genotype;<\/p>\n<p class=\"import-Normal\" style=\"padding-left: 40px\"><em>2pq<\/em> represents the frequency of the heterozygous genotype; and<\/p>\n<p class=\"import-Normal\" style=\"padding-left: 40px\"><em>q<\/em><sup><em>2<\/em><\/sup> represents the frequency of the homozygous recessive genotype.<\/p>\n<p class=\"import-Normal\">It is often easiest to determine <em>q<\/em><sup><em>2<\/em><\/sup> first, simply by counting the number of individuals with the unique, homozygous recessive phenotype (then dividing by the total individuals in the population to arrive at the \u201cfrequency\u201d). Once we have this number, we simply need to calculate the square root of the homozygous recessive phenotype frequency. That gives us <em>q.<\/em> Remember, 1 <em>\u2013<\/em> <em>q <\/em>equals <em>p<\/em>, so now we have the frequencies for both alleles in the population. If we needed to figure out the frequencies of heterozygotes and homozygous dominant genotypes, we\u2019d just need to plug the <em>p<\/em> and <em>q<\/em> frequencies back into the <em>p<\/em><sup><em>2<\/em><\/sup> and 2<em>pq<\/em> formulas.<\/p>\n<figure style=\"width: 329px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image25-1.png\" alt=\"A circle with seven grey and three white ladybugs.\" width=\"329\" height=\"347\" \/><figcaption class=\"wp-caption-text\">Figure 5.23: Ladybug population with a mixture of dark (red) and light (orange) individuals. Credit: <a class=\"rId129\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-3\/\">Ladybug mix (Figure 4.21)<\/a> original to <a class=\"rId130\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a class=\"rId131\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Let\u2019s imagine we have a population of ladybeetles that carries two alleles: a dominant allele that produces red ladybeetles and a recessive allele that produces orange ladybeetles. Since red is dominant, we\u2019ll use <em>R <\/em>to represent the red allele, and <em>r <\/em>to represent the orange allele. Our population has ten beetles, and seven are red and three are orange (Figure 5.23). Let\u2019s calculate the number of genotypes and alleles in this population.<\/p>\n<p class=\"import-Normal\">Of ten total beetles, we have three orange beetles3\/10 = .30 (30%) frequency\u2014and we know they are homozygous recessive (<em>rr<\/em>). So:<\/p>\n<p class=\"import-Normal\" style=\"text-indent: 36pt\"><em>rr = .3; <\/em>therefore, <em>r = <\/em>\u221a.3 = .5477<\/p>\n<p class=\"import-Normal\" style=\"text-indent: 36pt\"><em>R<\/em> = 1 <em>\u2013<\/em> .5477 = .4523<\/p>\n<p class=\"import-Normal\" style=\"text-indent: 36pt\">Using the Hardy-Weinberg formula:<\/p>\n<p class=\"import-Normal\" style=\"text-indent: 36pt\">1=.4523<sup>2 <\/sup>+ 2 x .4523 x .5477 +.5477<sup>2 <\/sup>= .20 + .50 + .30 = 1<\/p>\n<p class=\"import-Normal\" style=\"text-indent: 36pt\">Thus, the genotype breakdown is 20% <em>RR, <\/em>50%<em> Rr, <\/em>and 30%<em> rr <\/em><\/p>\n<p class=\"import-Normal\" style=\"text-indent: 36pt\">(2 red homozygotes, 5 red heterozygotes, and 3 orange homozygotes).<\/p>\n<p class=\"import-Normal\">Since we have 10 individuals, we know we have 20 total alleles: 4 red from the <em>RR<\/em> group, 5 red and 5 orange from the <em>Rr<\/em> group, and 6 orange from the <em>rr<\/em> group, for a grand total of 9 red and 11 orange (45% red and 55% orange, just like we estimated in the 1 \u2013 <em>q <\/em>step).<\/p>\n<p class=\"import-Normal\">Reminder: The Hardy-Weinberg formula only gives us an estimate for a snapshot in time. We will have to calculate it again later, after various intervals, to determine if our population is evolving and in what way the allele frequencies are changing.<\/p>\n<h3 class=\"import-Normal\"><strong>Interpreting Evolutionary Change: Nonra<\/strong><strong>ndom Mating <\/strong><\/h3>\n<p class=\"import-Normal\">Once we have detected change occurring in a population, we need to consider which evolutionary processes might be the cause of the change. It is important to watch for nonrandom mating patterns, to see if they can be included or excluded as possible sources of variation in allele frequencies.<\/p>\n<p class=\"import-Normal\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1498\"><strong>Nonrandom <\/strong><strong>m<\/strong><strong>ating<\/strong><\/a> (also known as assortative mating) occurs when mate choice within a population follows a nonrandom pattern.<\/p>\n<p class=\"import-Normal\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1499\"><strong>Positive assortative mating<\/strong><\/a> patterns result from a tendency for individuals to mate with others who share similar phenotypes. This often happens based on body size. Taking as an example dog breeds, it is easier for two Chihuahuas to mate and have healthy offspring than it is for a Chihuahua and a St. Bernard to do so. This is especially true if the Chihuahua is the female and would have to give birth to giant St. Bernard pups.<\/p>\n<p class=\"import-Normal\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1500\"><strong>Negative assortative mating<\/strong><\/a> patterns occur when individuals tend to select mates with qualities different from their own. This is what is at work when humans choose partners whose pheromones indicate that they have different and complementary immune alleles, providing potential offspring with a better chance at a stronger immune system.<\/p>\n<p class=\"import-Normal\">Among domestic animals, such as pets and livestock, assortative mating is often directed by humans who decide which pairs will mate to increase the chances of offspring having certain desirable traits. This is known as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1501\"><strong>a<\/strong><strong>rtificial <\/strong><strong>s<\/strong><strong>election<\/strong><em>.<\/em><\/a><\/p>\n<p class=\"import-Normal\">Among humans, in addition to phenotypic traits, cultural traits such as religion and ethnicity may also influence assortative mating patterns.<\/p>\n<h3 class=\"import-Normal\"><strong>Defining a Species<\/strong><\/h3>\n<p class=\"import-Normal\"><em>Species<\/em> are organisms whose individuals are capable of breeding because they are biologically and behaviourally compatible to produce viable, fertile offspring. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1502\"><strong>Viable offspring<\/strong><\/a> are those offspring that are healthy enough to survive to adulthood. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1503\"><strong>Fertile offspring<\/strong><\/a> are able to reproduce successfully, resulting in offspring of their own. Both conditions must be met for individuals to be considered part of the same species. As you can imagine, these criteria complicate the identification of distinct species in fossilized remains of extinct populations. In those cases, we must examine how much phenotypic variation is typically found within a comparable modern-day species; we can then determine whether the fossilized remains fall within the expected range of variation for a single species.<\/p>\n<p class=\"import-Normal\">Some species have subpopulations that are regionally distinct. These are classified as separate <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1505\">subspecies<\/a><\/strong> because they have their own unique phenotypes and are geographically isolated from one another. However, if they do happen to encounter one another, they are still capable of successful interbreeding.<\/p>\n<p class=\"import-Normal\">There are many examples of sterile hybrids that are offspring of parents from two different species. For example, horses and donkeys can breed and have offspring together. Depending on which species is the mother and which is the father, the offspring are either called mules, or hennies. Mules and hennies can live full life spans but are not able to have offspring of their own. Likewise, tigers and lions have been known to mate and have viable offspring. Again, depending on which species is the mother and which is the father, these offspring are called either ligers or tigons. Like mules and hennies, ligers and tigons are unable to reproduce. In each of these cases, the mismatched set of chromosomes that the offspring inherit produce an adequate set of functioning genes for the hybrid offspring; however, once mixed and divided in meiosis, the gametes don\u2019t contain the full complement of genes needed for survival in the third generation.<\/p>\n<h3 class=\"import-Normal\"><strong>Micro- to Macroevolution<\/strong><\/h3>\n<p class=\"import-Normal\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1506\"><strong>Microevolution<\/strong><\/a> refers to changes in allele frequencies within breeding populations\u2014that is, within single species. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1507\"><strong>Macroevolution<\/strong><\/a> describes how the similarities and differences between species, as well as the phylogenetic relationships with other taxa, lead to changes that result in the emergence of new species. Consider our example of the peppered moth that illustrated microevolution over time, via directional selection favouring the peppered allele when the trees were clean and the dark pigment allele when the trees were sooty. Imagine that environmental regulations had cleaned up the air pollution in one part of the nation, while the coal-fired factories continued to spew soot in another area. If this went on long enough, it\u2019s possible that two distinct moth populations would eventually emerge\u2014one containing only the peppered allele and the other only harbouring the dark pigment allele.<\/p>\n<p class=\"import-Normal\">When a single population divides into two or more separate species, it is called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1508\"><strong>speciation<\/strong><\/a>. The changes that prevent successful breeding between individuals who descended from the same ancestral population may involve chromosomal rearrangements, changes in the ability of the sperm from one species to permeate the egg membrane of the other species, or dramatic changes in hormonal schedules or mating behaviours that prevent members from the new species from being able to effectively pair up.<\/p>\n<p class=\"import-Normal\">There are two types of speciation: allopatric and sympatric. <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1509\">Allopatric speciation<\/a><\/strong> is caused by long-term <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1510\"><strong>isolation<\/strong><\/a> (physical separation) of subgroups of the population (Figure 5.24). Something occurs in the environment\u2014perhaps a river changes its course and splits the group, preventing them from breeding with members on the opposite riverbank. Over many generations, new mutations and adaptations to the different environments on each side of the river may drive the two subpopulations to change so much that they can no longer produce fertile, viable offspring, even if the barrier is someday removed.<\/p>\n<figure style=\"width: 1000px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image23-2.png\" alt=\"Process of isolation leading to speciation, as described in the figure caption.\" width=\"1000\" height=\"379\" \/><figcaption class=\"wp-caption-text\">Figure 5.24: Isolation leading to speciation: a. original population before isolation; b. a barrier divides the population and prevents interbreeding between the two groups; c. time passes, and the populations become genetically distinct; d. after many generations, the two populations are no longer biologically or behaviourally compatible, thus can no longer interbreed, even if the barrier is removed. Credit: <a class=\"rId121\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-3\/\">Isolation Leading to Speciation (Figure 4.19)<\/a> original to <a class=\"rId122\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a class=\"rId123\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\"><strong>Sympatric speciation<\/strong> occurs when the population splits into two or more separate species while remaining located together <em>without<\/em> a physical barrier. This typically results from a new mutation that pops up among some members of the population that prevents them from successfully reproducing with anyone who does not carry the same mutation. This is seen particularly often in plants, as they have a higher frequency of chromosomal duplications.<\/p>\n<p class=\"import-Normal\">One of the quickest rates of speciation is observed in the case of adaptive radiation. <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1512\">Adaptive radiation<\/a><\/strong> refers to the situation in which subgroups of a single species rapidly diversify and adapt to fill a variety of ecological niches. An <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1513\"><strong>e<\/strong><strong>cological niche<\/strong><\/a> is a set of constraints and resources that is available in an environmental setting. Evidence for adaptive radiations is often seen after population bottlenecks. A mass disaster kills off many species, and the survivors have access to a new set of territories and resources that were either unavailable or much coveted and fought over before the disaster. The offspring of the surviving population will often split into multiple species, each of which stems from members in that first group of survivors who happened to carry alleles that were advantageous for a particular niche.<\/p>\n<p class=\"import-Normal\">The classic example of adaptive radiation brings us back to Charles Darwin and his observations of the many species of finches on the Galapagos Islands. We are still not sure how the ancestral population of finches first arrived on that remote Pacific Island chain, but they found themselves in an environment filled with various insects, large and tiny seeds, fruit, and delicious varieties of cactus. Some members of that initial population carried alleles that gave them advantages for each of these dietary niches. In subsequent generations, others developed new mutations, some of which were beneficial. These traits were selected for, making the advantageous alleles more common among their offspring. As the finches spread from one island to the next, they would be far more likely to find mates among the birds on their new island. Birds feeding in the same area were then more likely to mate together than birds who have different diets, contributing to additional assortative mating. Together, these evolutionary mechanisms caused rapid speciation that allowed the new species to make the most of the various dietary niches (Figure 5.25).<\/p>\n<figure style=\"width: 619px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image24-1.png\" alt=\"A family tree of finches with different sized beaks.\" width=\"619\" height=\"325\" \/><figcaption class=\"wp-caption-text\">Figure 5.25: Darwin\u2019s finches demonstrating Adaptive Radiation. Credit: <a class=\"rId125\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-3\/\">Darwin\u2019s finches (Figure 4.20)<\/a> original to <a class=\"rId126\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a class=\"rId127\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">In today\u2019s modern world, understanding these evolutionary processes is crucial for developing immunizations and antibiotics that can keep up with the rapid mutation rate of viruses and bacteria. This is also relevant to our food supply, which relies, in large part, on the development of herbicides and pesticides that keep up with the mutation rates of pests and weeds. Viruses, bacteria, agricultural pests, and weeds have all shown great flexibility in developing alleles that make them resistant to the latest medical treatment, pesticide, or herbicide. Billion-dollar industries have specialized in trying to keep our species one step ahead of the next mutation in the pests and infectious diseases that put our survival at risk.<\/p>\n<h2>Cultural Connections and Contemporary Implications<\/h2>\n<h5>Sex within Culture and Biology<\/h5>\n<p>Research on bonobos (<em>Pan paniscus<\/em>) reveals a primate species whose social system relies heavily on affiliative and erotic behaviours rather than aggression. Bonobos live in fission\u2013fusion communities in Central African forests, where males remain in their natal groups and females migrate at adolescence. While sexual engagement is a large part of their social ecosystem, we see reproductive rates remain low, with females giving birth roughly every four to five years.<\/p>\n<p>Social cohesion among bonobos is strongly shaped by sexuality. Individuals engage frequently in diverse erotic behaviours; genital rubbing, oral contact, face-to-face copulation, and various forms of genital-to-genital stimulation are performed, but are not directly tied to reproduction. Through these modes of erotic sociality, tension is reduced, conflict is resolved, and food sharing is facilitated; all of which appear to function as peacemaking mechanisms integral to group stability. In this context, sexual pleasure is decoupled from reproduction, a parallel also found in human societies. Humans, like most primates, do not biologically mate for life; monogamy is a social contract, not a biological reality (Fuentes, 2012). Long-term exclusive mating is rare among primate species, and even in socially monogamous human groups, extra-pair copulations contribute substantially to reproductive outcomes.<\/p>\n<p>Human sexual development operates across genetic, hormonal, anatomical, and cultural levels. Biological traits such as chromosomal patterns or endocrine shifts interact with the social categories of gender, including transgender and transsexual identities (Fausto-Sterling, 1993, 2000a,b). Cultural expectations shape how sexual bodies are interpreted, often projecting ideological assumptions onto biological processes. This dynamic is exemplified in Emily Martin\u2019s (1991) critique of gendered metaphors in reproductive medical science, where egg and sperm are frequently described using stereotypically feminine or masculine language. Sexuality in humans is also neurologically mediated; as theorized by Freud, who suggested that humans possess undirected libidinal drives which society channels and constrains. With sex maintaining such sociocultural importance to humans, the anthropology of sex helps emphasize sexual practices, identities, and desires which emerge from the interplay of individual experience, interpersonal relationships, and broader cultural, political, and economic structures.<\/p>\n<h5>Archaeologies of Sexuality and the Future of Sex<\/h5>\n<p>Early archaeology commonly dismissed or obscured non-normative sexual imagery, classifying it under \u2018pornography\u2019 or \u2018Whore-Writing\u2019, a term introduced by the archaeologist M\u00fcller in 1850 to describe and demonize sexually explicit artifacts from Pompeii. Such categorizations reflected Victorian moral regimes rather than empirical assessment. Recent work highlights greater sexual and gender diversity in ancient material culture. Thousands of Ecuadorian clay figurines from 4400 BCE\u20131500 CE display non-binary and mixed-gender features, all of which were long-ignored or rationalized by earlier researchers (Ugalde, 2019). Later figurines exhibit more explicitly gendered poses, suggesting the gradual rise of patriarchal social structures.\u00a0<span style=\"margin: 0px;padding: 0px\">Simone de Beauvoir\u2019s\u00a0<em>The Second Sex<\/em> (1949) further explores this, arguing<\/span>\u00a0that women have historically been constructed as \u201cthe Other,\u201d a philosophical and social position that has shaped interpretations of sex, gender, and embodiment across cultures.<\/p>\n<p>Contemporary technological shifts prompt reconsideration of intimacy, embodiment, and sexual relationships. Robotics, avatars, and artificial companions raise questions about authenticity, relationality, and human\u2013machine attachment. Sherry Turkle (2011) argues that as people become increasingly anxious about interpersonal vulnerability, they may turn to machines for controlled forms of companionship and emotional safety. These developments illuminate broader transformations in how societies conceptualize relationships, desire, and human connection. They also challenge us to reconsider what counts as intimacy, what makes a relationship meaningful, and what ethical considerations arise when technologies substitute or reshape human sexual and emotional experience.<\/p>\n<h4>Discussion questions<\/h4>\n<ul>\n<li>With the rise of artificial companions, how might concepts such as intimacy, love, relationships, and sexuality be reconfigured? What might these changes reveal about how we understand human connection?<\/li>\n<li>How does studying sex and sexuality in other primates, such as bonobos, help us understand human sexuality and social behaviour? What are the limitations of using primates to understand humans?<\/li>\n<li>How might gendered metaphors and stereotypes influence the way scientific knowledge is produced and interpreted? Can you think of other examples where cultural assumptions have shaped scientific explanations?<\/li>\n<\/ul>\n<div class=\"textbox shaded\">\n<h2 class=\"import-Normal\">Review Questions<strong><br \/>\n<\/strong><\/h2>\n<ul>\n<li>Summarize the Modern Synthesis and provide several examples of how it is relevant to questions and problems in our world today.<\/li>\n<li>You inherit a house from a long-lost relative that contains a fancy aquarium, filled with a variety of snails. The phenotypes include large snails and small snails; red, black, and yellow snails; and solid, striped, and spotted snails. Devise a series of experiments that would help you determine how many snail species are present in your aquarium.<\/li>\n<li>Match the correct force of evolution with the correct real-world example:<br \/>\na. Mutationi. 5-alpha reductase deficiency<br \/>\nb. Genetic Driftii. Peppered Moths<br \/>\nc. Gene Flowiii. Neurofibromatosis Type 1<br \/>\nd. Natural Selectioniv. Scutellata Honey Bees<\/li>\n<li>Imagine a population of common house mice (<em>Mus musculus<\/em>). Draw a comic strip illustrating how mutation, genetic drift, gene flow, and natural selection might transform this population over several (or more) generations.<\/li>\n<li>\n<p class=\"import-Normal\">The many breeds of the single species of domestic dog (<em>Canis<\/em> <em>familiaris<\/em>) provide an extreme example of microevolution. Discuss why this is the case. What future scenarios can you imagine that could potentially transform the domestic dog into an example of macroevolution?<\/p>\n<\/li>\n<li>\n<p class=\"import-Normal\">The ability to roll one\u2019s tongue (lift the outer edges of the tongue to touch each other, forming a tube) is a dominant trait. In a small town of 1,500 people, 500 can roll their tongues. Use the Hardy-Weinberg formula to determine how many individuals in the town are homozygous dominant, heterozygous, and homozygous recessive.<\/p>\n<\/li>\n<\/ul>\n<\/div>\n<h2 class=\"import-Normal\">Key Terms<strong><br \/>\n<\/strong><\/h2>\n<p class=\"import-Normal\"><strong>5-alpha reductase deficiency<\/strong>: An autosomal recessive syndrome that manifests when a child having both X and Y sex chromosomes inherits two nonfunctional (mutated) copies of the SRD5A2 gene, producing a deficiency in a hormone necessary for development in infancy of typical male genitalia. These children often appear at birth to have female genitalia, but they develop a penis and other sexual characteristics when other hormones kick in during puberty.<\/p>\n<p class=\"import-Normal\"><strong>Adaptive radiation<\/strong>: The situation in which subgroups of a single species rapidly diversify and adapt to fill a variety of ecological niches.<\/p>\n<p class=\"import-Normal\"><strong>Admixture<\/strong>: A term often used to describe gene flow between human populations. Sometimes also used to describe gene flow between nonhuman populations.<\/p>\n<p class=\"import-Normal\"><strong>Allele frequency<\/strong>: The ratio, or percentage, of one allele compared to the other alleles for that gene within the study population.<\/p>\n<p class=\"import-Normal\"><strong>Alleles<\/strong>: Variant forms of genes.<\/p>\n<p class=\"import-Normal\"><strong>Allopatric speciation<\/strong>: Speciation caused by long-term isolation (physical separation) of subgroups of the population.<\/p>\n<p class=\"import-Normal\"><strong>Antibiotics<\/strong>: Medicines prescribed to treat bacterial infections.<\/p>\n<p class=\"import-Normal\"><strong>Artificial selection<\/strong>: Human-directed assortative mating among domestic animals, such as pets and livestock, designed to increase the chances of offspring having certain desirable traits.<\/p>\n<p class=\"import-Normal\"><strong>Asexual reproduction<\/strong>: Reproduction via mitosis, whereby offspring are clones of the parents.<\/p>\n<p class=\"import-Normal\"><strong>Autosomal dominant<\/strong>: A phenotype produced by a gene on an autosomal chromosome that is expressed, to the exclusion of the recessive phenotype, in heterozygotes.<\/p>\n<p class=\"import-Normal\"><strong>Autosomal recessive<\/strong>: A phenotype produced by a gene on an autosomal chromosome that is expressed only in individuals homozygous for the recessive allele.<\/p>\n<p class=\"import-Normal\"><strong>Balanced translocations<\/strong>: Chromosomal translocations in which the genes are swapped but no genetic information is lost.<\/p>\n<p class=\"import-Normal\"><strong>Balancing selection<\/strong>: A pattern of natural selection that occurs when the extremes of a trait are selected against, favouring the intermediate phenotype (a.k.a. stabilizing selection).<\/p>\n<p class=\"import-Normal\"><strong>Beneficial mutations<\/strong>: Mutations that produce some sort of an advantage to the individual.<\/p>\n<p class=\"import-Normal\"><strong>Benign<\/strong>: Noncancerous. Benign tumors may cause problems due to the area in which they are located (e.g., they might put pressure on a nerve or brain area), but they will not release cells that aggressively spread to other areas of the body.<\/p>\n<p class=\"import-Normal\"><strong>Caf\u00e9-au-lait spots (CALS)<\/strong>: Flat, brown birthmark-like spots on the skin, commonly associated with Neurofibromatosis Type 1.<\/p>\n<p class=\"import-Normal\"><strong>Chromosomal translocations<\/strong>: The transfer of DNA between nonhomologous chromosomes.<\/p>\n<p class=\"import-Normal\"><strong>Chromosomes<\/strong>: Molecules that carry collections of genes.<\/p>\n<p class=\"import-Normal\"><strong>Codons<\/strong>: Three-nucleotide units of DNA that function as three-letter \u201cwords,\u201d encoding instructions for the addition of one amino acid to a protein or indicating that the protein is complete.<\/p>\n<p class=\"import-Normal\"><strong>Cretaceous\u2013Paleogene extinction<\/strong>: A mass disaster caused by an asteroid that struck the earth approximately 66 million years ago and killed 75% of life on Earth, including all terrestrial dinosaurs. (a.k.a. K-Pg Extinction, Cretatious-Tertiary Extinction, and K-T Extinction).<\/p>\n<p class=\"import-Normal\"><strong>Crossover events<\/strong>: Chromosomal alterations that occur when DNA is swapped between homologous chromosomes while they are paired up during meiosis I.<\/p>\n<p class=\"import-Normal\"><strong>Cutaneous neurofibromas<\/strong>: Neurofibromas that manifest as spherical bumps on or just under the surface of the skin.<\/p>\n<p class=\"import-Normal\"><strong>Deleterious mutation<\/strong>: A mutation producing negative effects to the individual such as the beginnings of cancers or heritable disorders.<\/p>\n<p class=\"import-Normal\"><strong>Deletions<\/strong>: Mutations that involve the removal of one or more nucleotides from a DNA sequence.<\/p>\n<p class=\"import-Normal\"><strong>Derivative chromosomes<\/strong>: New chromosomal structures resulting from translocations.<\/p>\n<p class=\"import-Normal\"><strong><em>Dictyostelium discoideum<\/em><\/strong>: A species of social amoebae that has been widely used for laboratory research. Laboratory strains of <em>Dictyostelium discoideum <\/em>all carry mutations in the <em>NF1<\/em> gene, which is what allows them to survive on liquid media (agar) in Petri dishes.<\/p>\n<p class=\"import-Normal\"><strong>Directional selection<\/strong>: A pattern of natural selection in which one phenotype is favoured over the other, causing the frequencies of the associated advantageous alleles to gradually increase.<\/p>\n<p class=\"import-Normal\"><strong>Disruptive selection<\/strong>: A pattern of natural selection that occurs when both extremes of a trait are advantageous and intermediate phenotypes are selected against (a.k.a. diversifying selection).<\/p>\n<p class=\"import-Normal\"><strong>DNA repair mechanisms<\/strong>: Enzymes that patrol and repair DNA in living cells.<\/p>\n<p class=\"import-Normal\"><strong>DNA transposons<\/strong>: Transposons that are clipped out of the DNA sequence itself and inserted elsewhere in the genome.<\/p>\n<p class=\"import-Normal\"><strong>Ecological niche<\/strong>: A set of constraints and resources that are available in an environmental setting.<\/p>\n<p class=\"import-Normal\"><strong>Ellis-van Creveld syndrome<\/strong>: An autosomal recessive disorder characterized by short stature (dwarfism), polydactyly (the development of more than five digits [fingers or toes] on the hands or feet), abnormal tooth development, and heart defects. Estimated to affect approximately one in 60,000 individuals worldwide, among the Old Order Amish of Lancaster County, the rate is estimated to be as high as one in every 200 births.<\/p>\n<p class=\"import-Normal\"><strong>Evolution<\/strong>: A change in the allele frequencies in a population over time.<\/p>\n<p class=\"import-Normal\"><strong>Exons<\/strong>: The DNA sequences within a gene that directly encode protein sequences. After being transcribed into messenger RNA, the introns (DNA sequences within a gene that do not directly encode protein sequences) are clipped out, and the exons are pasted together prior to translation.<\/p>\n<p class=\"import-Normal\"><strong>Fertile offspring<\/strong>: Offspring that can successfully reproduce, resulting in offspring of their own.<\/p>\n<p class=\"import-Normal\"><strong>Founder effect<\/strong>: A type of genetic drift that occurs when members of a population leave the main or \u201cparent\u201d group and form a new population that no longer interbreeds with the other members of the original group.<\/p>\n<p class=\"import-Normal\"><strong>Frameshift mutations<\/strong>: Types of indels that involve the insertion or deletion of any number of nucleotides that is not a multiple of three. These \u201cshift the reading frame\u201d and cause all codons beyond the mutation to be misread.<\/p>\n<p class=\"import-Normal\"><strong>Gametes<\/strong>: The reproductive cells, produced through meiosis (a.k.a. germ cells or sperm or egg cells).<\/p>\n<p class=\"import-Normal\"><strong>Gene<\/strong>: A sequence of DNA that provides coding information for the construction of proteins.<\/p>\n<p class=\"import-Normal\"><strong>Gene flow<\/strong>: The movement of alleles from one population to another. This is one of the forces of evolution.<\/p>\n<p class=\"import-Normal\"><strong>Gene pool<\/strong>: The entire collection of genetic material in a breeding community that can be passed on from one generation to the next.<\/p>\n<p class=\"import-Normal\"><strong>Genetic drift<\/strong>: Random changes in allele frequencies within a population from one generation to the next. This is one of the forces of evolution.<\/p>\n<p class=\"import-Normal\"><strong>Genotype<\/strong>: The set of alleles that an individual has for a given gene.<\/p>\n<p class=\"import-Normal\"><strong>Genotype frequencies<\/strong>: The ratios or percentages of the different homozygous and heterozygous genotypes in the population.<\/p>\n<p class=\"import-Normal\"><strong><em>Guevedoces<\/em><\/strong>: The term coined locally in the Dominican Republic for the condition scientifically known as 5-alpha reductase deficiency. The literal translation is \u201cpenis at twelve.\u201d<\/p>\n<p class=\"import-Normal\"><strong>Hardy-Weinberg Equilibrium<\/strong>: A mathematical formula (<em>1=p<\/em><sup><em>2<\/em><\/sup><em> + 2pq + q<\/em><sup><em>2<\/em><\/sup> ) that allows estimation of the number and distribution of dominant and recessive alleles in a population.<\/p>\n<p class=\"import-Normal\"><strong>Harlequin ladybeetle<\/strong>: A species of ladybeetle, native to East Asia, that was introduced to Europe and the Americas as a form of pest control. After many decades of use, one of the North American strains developed the ability to reproduce in diverse environments, causing it to spread rapidly throughout the Americas, Europe, and Africa. It has hybridized with European strains and is now a major pest in its own right.<\/p>\n<p class=\"import-Normal\"><strong>Heterozygous genotype<\/strong>: A genotype comprising two different alleles.<\/p>\n<p class=\"import-Normal\"><strong>Homozygous genotype<\/strong>: A genotype comprising an identical set of alleles.<\/p>\n<p class=\"import-Normal\"><strong>Hybridization<\/strong>: A term often used to describe gene flow between nonhuman populations.<\/p>\n<p class=\"import-Normal\"><strong>Inbreeding<\/strong>: The selection of mates exclusively from within a small, closed population.<\/p>\n<p class=\"import-Normal\"><strong>Indels<\/strong>: A class of mutations that includes both insertions and deletions.<\/p>\n<p class=\"import-Normal\"><strong>Inherited mutation<\/strong>: A mutation that has been passed from parent to offspring.<\/p>\n<p class=\"import-Normal\"><strong>Insertions<\/strong>: Mutations that involve the addition of one or more nucleotides into a DNA sequence.<\/p>\n<p class=\"import-Normal\"><strong>Isolation<\/strong>: Prevention of a population subgroup from breeding with other members of the same species due to a physical barrier or, in humans, a cultural rule.<\/p>\n<p class=\"import-Normal\"><strong>Last Universal Common Ancestor (LUCA)<\/strong>: The ancient organism from which all living things on Earth are descended.<\/p>\n<p class=\"import-Normal\"><strong>Macroevolution<\/strong>: Changes that result in the emergence of new species, how the similarities and differences between species, as well as the phylogenetic relationships with other taxa, lead to changes that result in the emergence of new species.<\/p>\n<p class=\"import-Normal\"><strong>Malaria<\/strong>: A frequently deadly mosquito-borne disease caused by infection of the blood by a <em>Plasmodium<\/em> parasite.<\/p>\n<p class=\"import-Normal\"><strong>Malignant<\/strong>: Cancerous. Malignant tumors grow aggressively and their cells may metastasize (travel through the blood or lymph systems) to form new, aggressive tumors in other areas of the body.<\/p>\n<p class=\"import-Normal\"><strong>Microevolution<\/strong>: Changes in allele frequencies within breeding populations\u2014that is, within a single species.<\/p>\n<p class=\"import-Normal\"><strong>Modern Synthesis<\/strong>: The integration of Darwin\u2019s, Mendel\u2019s, and subsequent research into a unified theory of evolution.<\/p>\n<p class=\"import-Normal\"><strong>Monosomies<\/strong>: Conditions resulting from a nondisjunction event, in which a cell ends up with only one copy of a chromosome. In humans, a single X chromosome is the only survivable monosomy.<\/p>\n<p class=\"import-Normal\"><strong>Mutation<\/strong>: A change in the nucleotide sequence of the genetic code. This is one of the forces of evolution.<\/p>\n<p class=\"import-Normal\"><strong>Natural selection<\/strong>: An evolutionary process that occurs when certain phenotypes confer an advantage or disadvantage in survival and\/or reproductive success. This is one of the forces of evolution, and it was first identified by Charles Darwin.<\/p>\n<p class=\"import-Normal\"><strong>Negative assortative mating<\/strong>: A pattern that occurs when individuals tend to select mates with qualities different from their own.<\/p>\n<p class=\"import-Normal\"><strong>Neurofibromas<\/strong>: Nerve sheath tumors that are common symptoms of Neurofibromatosis Type 1.<\/p>\n<p class=\"import-Normal\"><strong>Neurofibromatosis Type 1<\/strong>: An autosomal dominant genetic disorder affecting one in every 3,000 people. It is caused by mutation of the <em>NF1<\/em> gene on Chromosome 17, resulting in a defective neurofibromin protein. The disorder is characterized by neurofibromas, caf\u00e9-au-lait spots, and a host of other potential symptoms.<\/p>\n<p class=\"import-Normal\"><strong>NF1<\/strong>: An abbreviation for Neurofibromatosis Type 1. When italicized, <em>NF1 <\/em>refers to the gene on Chromosome 17 that encodes the neurofibromin protein.<\/p>\n<p class=\"import-Normal\"><strong>Nondisjunction events<\/strong>: Chromosomal abnormalities that occur when the homologous chromosomes (in meiosis I) or sister chromatids (in meiosis II and mitosis) fail to separate after pairing. The result is that both chromosomes or chromatids end up in the same daughter cell, leaving the other daughter cell without any copy of that chromosome.<\/p>\n<p class=\"import-Normal\"><strong>Nonrandom mating<\/strong>: A scenario in which mate choice within a population follows a nonrandom pattern (a.k.a. assortative mating).<\/p>\n<p class=\"import-Normal\"><strong>Nonsynonymous mutation<\/strong>: A point mutation that causes a change in the resulting protein.<\/p>\n<p class=\"import-Normal\"><strong>Old Order Amish<\/strong>: A culturally isolated population in Lancaster County, Pennsylvania, that has approximately 50,000 current members, all of whom can trace their ancestry back to a group of approximately eighty individuals. This group has high rates of certain genetics disorders, including Ellis-van Creveld syndrome.<\/p>\n<p class=\"import-Normal\"><strong>Origins of life<\/strong>: How the first living organism came into being.<\/p>\n<p class=\"import-Normal\"><strong>Peacock<\/strong>: The male sex of the peafowl, famous for its large, colourful tail, which it dramatically displays to attract mates. (The female of the species is known as a peahen.)<\/p>\n<p class=\"import-Normal\"><strong>Peppered moth<\/strong>: A species of moth (<em>Biston betularia<\/em>) found in England that has light and dark phenotypes. During the Industrial Revolution, when soot blackened the trees, the frequency of the previously rare dark phenotype dramatically increased, as lighter-coloured moths were easier for birds to spot against the sooty trees. After environmental regulations eliminated the soot, the lighter-coloured phenotype gradually became most common again.<\/p>\n<p class=\"import-Normal\"><strong>Phenotype<\/strong>: The observable traits that are produced by a genotype.<\/p>\n<p class=\"import-Normal\"><strong>Phylogenetic tree of life<\/strong>: A family tree of all living organisms, based on genetic relationships.<\/p>\n<p class=\"import-Normal\"><strong>Phylogenies<\/strong>: Genetically determined family lineages.<\/p>\n<p class=\"import-Normal\"><strong><em>Plasmodium<\/em><\/strong>: A genus of mosquito-borne parasite. Several <em>Plasmodium<\/em> species cause malaria when introduced to the human bloodstream via a mosquito bite.<\/p>\n<p class=\"import-Normal\"><strong>Plexiform neurofibromas<\/strong>: Neurofibromas that involve whole branches of nerves, often giving the appearance that the surface of the skin is \u201cmelting.\u201d<\/p>\n<p class=\"import-Normal\"><strong>Point mutation<\/strong>: A single-letter (single-nucleotide) change in the genetic code, resulting in the substitution of one nucleic acid base for a different one.<\/p>\n<p class=\"import-Normal\"><strong>Polymorphisms<\/strong>: Multiple forms of a trait; alternative phenotypes within a given species.<\/p>\n<p class=\"import-Normal\"><strong>Population<\/strong>: A group of individuals who are genetically similar enough and geographically near enough to one another that they can breed and produce new generations of individuals.<\/p>\n<p class=\"import-Normal\"><strong>Population bottleneck<\/strong>: A type of genetic drift that occurs when the number of individuals in a population drops dramatically due to some random event.<\/p>\n<p class=\"import-Normal\"><strong>Positive assortative mating<\/strong>: A pattern that results from a tendency for individuals to mate with others who share similar phenotypes.<\/p>\n<p class=\"import-Normal\"><strong>Retrotransposons<\/strong>: Transposons that are transcribed from DNA into RNA, and then are \u201creverse transcribed,\u201d to insert the copied sequence into a new location in the DNA.<\/p>\n<p class=\"import-Normal\"><strong>Scutellata honey bees<\/strong>: A strain of honey bees that resulted from the hybridization of African and European honey bee subspecies. These bees were accidentally released into the wild in 1957 in Brazil and have since spread throughout South and Central America and into the United States. Also known as \u201ckiller bees,\u201d they tend to be very aggressive in defence of their hives and have caused many fatal injuries to humans and livestock.<\/p>\n<p class=\"import-Normal\"><strong>Sexual reproduction<\/strong>: Reproduction via meiosis and combination of gametes. Offspring inherit genetic material from both parents.<\/p>\n<p class=\"import-Normal\"><strong>Sexual selection<\/strong>: An aspect of natural selection in which the selective pressure specifically affects reproductive success (the ability to successfully breed and raise offspring).<\/p>\n<p class=\"import-Normal\"><strong>Sickle cell anemia<\/strong>: An autosomal recessive genetic disorder that affects millions of people worldwide. It is most common in Africa, countries around the Mediterranean Sea, and eastward as far as India. Homozygotes for the recessive allele develop the disorder, which produce misshapen red blood cells that cause iron deficiency, painful episodes of oxygen-deprivation in localized tissues, and a host of other symptoms. In heterozygotes, though, the sickle cell allele confers a greater resistance to malaria.<\/p>\n<p class=\"import-Normal\"><strong>Somatic cells<\/strong>: The cells of our organs and other body tissues (all cells except gametes) that replicate by mitosis.<\/p>\n<p class=\"import-Normal\"><strong>Speciation<\/strong>: The process by which a single population divides into two or more separate species.<\/p>\n<p class=\"import-Normal\"><strong>Species<\/strong>: Organisms whose individuals are capable of breeding because they are biologically and behaviourally compatible to produce viable, fertile offspring.<\/p>\n<p class=\"import-Normal\"><strong>Spontaneous mutation<\/strong>: A mutation that occurs due to random chance or unintentional exposure to mutagens. In families, a spontaneous mutation is the first case, as opposed to mutations that are inherited from parents.<\/p>\n<p class=\"import-Normal\"><strong>Subspecies<\/strong>: A distinct subtype of a species. Most often, this is a geographically isolated population with unique phenotypes; however, it remains biologically and behaviourally capable of interbreeding with other populations of the same species.<\/p>\n<p class=\"import-Normal\"><strong>Sympatric speciation<\/strong>: When a population splits into two or more separate species while remaining located together without a physical (or cultural) barrier.<\/p>\n<p class=\"import-Normal\"><strong>Synonymous mutation<\/strong>: A point mutation that does not change the resulting protein.<\/p>\n<p class=\"import-Normal\"><strong>Transposable elements<\/strong>: Fragments of DNA that can \u201cjump\u201d around in the genome.<\/p>\n<p class=\"import-Normal\"><strong>Transposon<\/strong>: Another term for \u201ctransposable element.\u201d<\/p>\n<p class=\"import-Normal\"><strong>Trisomies<\/strong>: Conditions in which three copies of the same chromosome end up in a cell, resulting from a nondisjunction event. Down syndrome, Edwards syndrome, and Patau syndrome are trisomies.<\/p>\n<p class=\"import-Normal\"><strong>Unbalanced translocations<\/strong>: Chromosomal translocations in which there is an unequal exchange of genetic material, resulting in duplication or loss of genes.<\/p>\n<p class=\"import-Normal\"><strong>UV crosslinking<\/strong>: A type of mutation in which adjacent thymine bases bind to one another in the presence of UV light.<\/p>\n<p class=\"import-Normal\"><strong>Viable offspring<\/strong>: Offspring that are healthy enough to survive to adulthood.<\/p>\n<p class=\"import-Normal\"><strong>Xeroderma pigmentosum<\/strong>: An autosomal recessive disease in which DNA repair mechanisms do not function correctly, resulting in a host of problems especially related to sun exposure, including severe sunburns, dry skin, heavy freckling, and other pigment changes.<\/p>\n<h2 class=\"import-Normal\">For Further Exploration<\/h2>\n<p>Explore Evolution on <a href=\"https:\/\/www.hhmi.org\/biointeractive\/evolution-collection\">HHMI\u2019s Biointeractive website<\/a>.<\/p>\n<p>Teaching Evolution through <a href=\"https:\/\/humanorigins.si.edu\/education\/teaching-evolution-through-human-examples\">Human Examples, Smithsonian Museum of Natural History websites<\/a>.<\/p>\n<h2 class=\"import-Normal\">References<\/h2>\n<p class=\"import-Normal\">Bloomfield, Gareth, David Traynor, Sophia P. Sander, Douwe M. Veltman, Justin A. Pachebat, and Robert R. Kay. 2015. \u201cNeurofibromin Controls Macropinocytosis and Phagocytosis in <em>Dictyostelium<\/em>.\u201d <em>eLife<\/em> 4:e04940.<\/p>\n<p class=\"import-Normal\">Chaix, Rapha\u00eblle, Chen Cao, and Peter Donnelly. 2008. \u201cIs Mate Choice in Humans MHC-Dependent?\u201d <em>PLoS Genetics<\/em> 4 (9): e1000184.<\/p>\n<p class=\"import-Normal\">Cook, Laurence M. 2003. \"The Rise and Fall of the <em>Carbonaria<\/em> Form of the Peppered Moth.\" <em>The Quarterly Review of Biology<\/em> 78 (4): 399\u2013417.<\/p>\n<p class=\"import-Normal\">Cota, Bruno C\u00e9zar Lage, Jo\u00e3o Gabriel Marques Fonseca, Luiz Oswaldo Carneiro Rodrigues, Nilton Alves de Rezende, Pollyanna Barros Batista, Vincent Michael Riccardi, and Luciana Macedo de Resende. 2018. \u201cAmusia and Its Electrophysiological Correlates in Neurofibromatosis Type 1.\u201d <em>Arquivos de Neuro-Psiquiatria<\/em> 76 (5): 287\u2013295.<\/p>\n<p class=\"import-Normal\">D\u2019Asdia, Maria Cecilia, Isabella Torrente, Federica Consoli, Rosangela Ferese, Monia Magliozzi, Laura Bernardini, Valentina Guida, et al. 2013. \u201cNovel and Recurrent EVC and EVC2 Mutations in Ellis-van Creveld Syndrome and Weyers Acrofacial Dyostosis.\u201d <em>European Journal of Medical Genetics<\/em> 56 (2): 80\u201387.<\/p>\n<p>de Beauvoir, S. (2009). <em>The Second Sex<\/em> (C. Borde &amp; S. Malovany-Chevallier, Trans.). Vintage Books. (Original work published 1949)<\/p>\n<p class=\"import-Normal\">Dobzhansky, Theodosius. 1937. <em>Genetics and the Origin of Species. <\/em>Columbia University Biological Series. New York: Columbia University Press.<\/p>\n<p class=\"import-Normal\">Facon, Beno\u00eet, Laurent Crespin, Anne Loiseau, Eric Lombaert, Alexandra Magro, and Arnaud Estoup. 2011. \u201cCan Things Get Worse When an Invasive Species Hybridizes? The Harlequin Ladybird <em>Harmonia axyridis<\/em> in France as a Case Study.\u201d <em>Evolutionary Applications<\/em> 4 (1): 71\u201388.<\/p>\n<p>Fausto-Sterling, A. (1993). The five sexes: Why male and female are not enough. <em>The Sciences;<\/em> 33(2):20\u201325.<\/p>\n<p>Fausto-Sterling, A. (2000a). The Five Sexes Revisited. <em>The Sciences; <\/em>40(4):18-23<\/p>\n<p>Fausto-Sterling, A. (2000b). <em>Sexing the body: Gender politics and the construction of sexuality<\/em>. Basic Books.<\/p>\n<p class=\"import-Normal\">Fisher, Ronald A. 1919. \"The Correlation between Relatives on the Supposition of Mendelian Inheritance.\" <em>Transactions of the Royal Society of Edinburgh<\/em> 52 (2): 399\u2013433.<\/p>\n<p class=\"import-Normal\">Ford, E. B. 1942. <em>Genetics for Medical Students<\/em>. London: Methuen.<\/p>\n<p class=\"import-Normal\" style=\"background-color: #ffffff\">Ford, E. B. 1949. <em>Mendelism and Evolution<\/em>. London: Methuen.<\/p>\n<p>Fuentes, A. (2012). <em>Race, monogamy, and other lies they told you: Busting myths about human nature<\/em>. University of California Press.<\/p>\n<p class=\"import-Normal\">Grant, Bruce S. 1999. \u201cFine-tuning the Peppered Moth Paradigm.\u201d <em>Evolution<\/em> 53 (3): 980\u2013984.<\/p>\n<p class=\"import-Normal\">Haldane, J. B. S. 1924. \u201cA Mathematical Theory of Natural and Artificial Selection (Part 1).\u201d <em>Transactions of the Cambridge Philosophical Society<\/em> 23 (2):19\u201341.<\/p>\n<p>Hoelzel, A. R., Gkafas, G. A., Kang, H., Sarigol, F., Le Boeuf, B., Costa, D. P., Beltran, R. S., Reiter, J., Robinson, P. W., McInerney, N., Seim, I., Sun, S., Fan, G., &amp; Li, S. (2024). Genomics of post-bottleneck recovery in the northern elephant seal. Nature Ecology &amp; Evolution, 8, 686\u2013694. https:\/\/doi.org\/10.1038\/s41559-024-02337-4<\/p>\n<p>Hurst, L. D. (1996). Why are there only two sexes? <em>Proceedings of the Royal Society, London B<\/em>, 263; 415-422.<\/p>\n<p class=\"import-Normal\">Imperato-McGinley, J., and Y.-S. Zhu. 2002. \u201cAndrogens and Male Physiology: The Syndrome of 5 Alpha-Reductase-2 Deficiency.\u201d <em>Molecular and Cellular Endocrinology <\/em>198 (1-2): 51\u201359.<\/p>\n<p class=\"import-Normal\">Jablonski, David, and W. G. Chaloner. 1994. \"Extinctions in the Fossil Record.\u201d <em>Philosophical Transactions of the Royal Society of London B: Biological Sciences<\/em> 344 (1307): 11\u201317.<\/p>\n<p>Kinsey, A. C., Pomeroy, W. B., &amp; Martin, C. E. (1948). <em>Sexual behavior in the human male<\/em>. W.B. Saunders.<\/p>\n<p>Kinsey, A. C., Pomeroy, W. B., Martin, C. E., &amp; Gebhard, P. H. (1953). <em>Sexual behavior in the human female<\/em>. W.B. Saunders.<\/p>\n<p class=\"import-Normal\">Livi-Bacci, Massimo. 2006. \u201cThe Depopulation of Hispanic America after the Conquest.\u201d <em>Population Development and Review<\/em> 32 (2): 199\u2013232.<\/p>\n<p class=\"import-Normal\">Lombaert, Eric, Thomas Guillemaud, Jean-Marie Cornuet, Thibaut Malausa, Beno\u00eet Facon, and Arnaud Estoup. 2010. \"Bridgehead Effect in the Worldwide Invasion of the Biocontrol Harlequin Ladybird.\u201d <em>PLoS ONE<\/em> 5 (3): e9743.<\/p>\n<p>Martin, E. (1991). The egg and the sperm: How science has constructed a romance based on stereotypical male\u2013female roles. <em>Signs,<\/em> 16(3), 485\u2013501.<\/p>\n<p class=\"import-Normal\">Martins, Aline Stangherlin, Ann Kristine Jansen, Luiz Oswaldo Carneiro Rodrigues, Camila Maria Matos, Marcio Leandro Ribeiro Souza, Juliana Ferreira de Souza, Maria de F\u00e1tima Haueisen Sander Diniz, et al. 2016. \u201cLower Fasting Blood Glucose in Neurofibromatosis Type 1.\u201d <em>Endocrine Connections<\/em> 5 (1): 28\u201333.<\/p>\n<p class=\"import-Normal\">Pickering, Gary, James Lin, Roland Riesen, Andrew Reynolds, Ian Brindle, and George Soleas. 2004. \"Influence of <em>Harmonia axyridis<\/em> on the Sensory Properties of White and Red Wine.\" <em>American Journal of Enology and Viticulture<\/em> 55 (2): 153\u2013159.<\/p>\n<p class=\"import-Normal\">Repunte-Canonigo Vez, Melissa A. Herman, Tomoya Kawamura, Henry R. Kranzler, Richard Sherva, Joel Gelernter, Lindsay A. Farrer, Marisa Roberto, and Pietro Paolo Sanna. 2015. \u201cNF1 Regulates Alcohol Dependence-Associated Excessive Drinking and Gamma-Aminobutyric Acid Release in the Central Amygdala in Mice and Is Associated with Alcohol Dependence in Humans.\u201d <em>Biological Psychiatry<\/em> 77 (10): 870\u2013879.<\/p>\n<p class=\"import-Normal\">Riccardi, Vincent M. 1992. <em>Neurofibromatosis: Phenotype, Natural History, and Pathogenesis.<\/em> Baltimore: Johns Hopkins University Press.<\/p>\n<p class=\"import-Normal\">Sanford, Malcolm T. 2006. \"The Africanized Honey Bee in the Americas: A Biological Revolution with Human Cultural Implications, Part V\u2014Conclusion.\" <em>American Bee Journal <\/em>146 (7): 597\u2013599.<\/p>\n<p class=\"import-Normal\">Sanna, Pietro Paolo, Cindy Simpson, Robert Lutjens, and George Koob. 2002. \u201cERK Regulation in Chronic Ethanol Exposure and Withdrawal.\u201d <em>Brain Research<\/em> 948 (1\u20132): 186\u2013191.<\/p>\n<p>Turkle, S. (2011). <em>Alone together: Why we expect more from technology and less from each other<\/em>. Basic Books.<\/p>\n<p>Ugalde, Mar\u00eda Fernanda. 2019. \u201cThe Rebel Potters: A Review of Gender Relations, Female Oppression, and Patriarchy from the Perspective of Ecuadorian Archaeology.\u201d Translated by Tiziana Laudato. <em>Ant\u00edpoda. Revista de Antropolog\u00eda y Arqueolog\u00eda<\/em> 36: 1-23. https:\/\/doi.org\/10.7440\/antipoda36.2019.03<\/p>\n<p>Weber, DianaS., Stewart, B. S., Garza, J. Carlos., &amp; Lehman, N. (2000). An empirical genetic assessment of the severity of the northern elephant seal population bottleneck. Current Biology, 10(20), 1287\u20131290. https:\/\/doi.org\/10.1016\/s0960-9822(00)00759-4<\/p>\n<p class=\"import-Normal\">World Health Organization. 1996. \u201cControl of Hereditary Disorders: Report of WHO Scientific meeting (1996).\u201d WHO Technical Reports 865. Geneva: World Health Organization.<\/p>\n<p class=\"import-Normal\">World Health Organization. 2017. \u201cGlobal Priority List of Antibiotic-Resistant Bacteria to Guide Research, Discovery, and Development of New Antibiotics.\u201d Global Priority Pathogens List, February 27. Geneva: World Health Organization. https:\/\/www.who.int\/medicines\/publications\/WHO-PPL-Short_Summary_25Feb-ET_NM_WHO.pdf.<\/p>\n<p class=\"import-Normal\">Wright, Sewall. 1932. \"The Roles of Mutation, Inbreeding, Crossbreeding, and Selection in Evolution.\" <em>Proceedings of the Sixth International Congress on Genetics<\/em> 1 (6): 356\u2013366.<\/p>\n<h2 class=\"import-Normal\">Acknowledgement<strong><br \/>\n<\/strong><\/h2>\n<p class=\"import-Normal\">Many thanks to Dr. Vincent M. Riccardi for sharing his vast knowledge of neurofibromatosis and for encouraging me to explore it from an anthropological perspective.<\/p>\n<\/div>\n<\/div>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1695_1851\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1695_1851\"><div tabindex=\"-1\"><div class=\"__UNKNOWN__\">\n<div class=\"textbox\">\n<h6>Student contributors for this chapter from Salinda Hess' ANTH 203: Corin Laberge, Hazel Moorcroft, Isabella Michel, Julian J. Pantoja Quiroz<\/h6>\n<p>Learn more about <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/about-the-authors\/\">authors and editors<\/a>,<a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/student-contributors\/\"> Hess' student contributions<\/a>, and <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/versioning-history\/\">versioning history<\/a>.<\/p>\n<\/div>\n<div class=\"textbox textbox--learning-objectives\">\n<header class=\"textbox__header\">\n<h2 class=\"textbox__title\">Learning Objectives<\/h2>\n<\/header>\n<div class=\"textbox__content\">\n<ul>\n<li class=\"import-Normal\">Outline a 21st-century perspective of the Modern Synthesis.<\/li>\n<li class=\"import-Normal\">Define populations and population genetics as well as the methods used to study them.<\/li>\n<li class=\"import-Normal\">Identify the forces of evolution and become familiar with examples of each.<\/li>\n<li class=\"import-Normal\">Discuss the evolutionary significance of mutation, genetic drift, gene flow, and natural selection.<\/li>\n<li class=\"import-Normal\">Explain how allele frequencies can be used to study evolution as it happens.<\/li>\n<li class=\"import-Normal\">Contrast micro- and macroevolution.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<p>It\u2019s hard for us, with our typical human life spans of less than 100 years, to imagine all the way back, 3.8 billion years ago, to the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1442\">origins of life<\/a><\/strong>. Scientists still study and debate how life came into being and whether it originated on Earth or in some other region of the universe (including some scientists who believe that studying evolution can reveal the complex processes that were set in motion by God or a higher power). What we do know is that a living single-celled organism was present on Earth during the early stages of our planet\u2019s existence. This organism had the potential to reproduce by making copies of itself, just like bacteria, many amoebae, and our own living cells today. In fact, with modern technologies, we can now trace genetic lineages, or <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1290\">phylogenies<\/a><\/strong>, and determine the relationships between all of today\u2019s living organisms\u2014eukaryotes (animals, plants, fungi, etc.), archaea, and bacteria\u2014on the branches of the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1444\">phylogenetic tree of life<\/a><\/strong> (Figure 5.1).<\/p>\n<figure style=\"width: 675px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2023\/02\/image1-1.png\" alt=\"Branches lead off of a single celled universal ancestor to images of bacteria, archaea, and eukarya (represented by a mouse, mushroom, and fern, among others).\" width=\"675\" height=\"475\" \/><figcaption class=\"wp-caption-text\">Figure 5.1: Phylogenetic tree of life illustrating probable relationships between the single-celled Last Universal Common Ancestor (LUCA) and select examples of bacteria, archaea, and eukaryotes. Major evolutionary developments, including independent evolution of multicellularity, photosynthesis, and respiration, are indicated along the branches. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available<\/a>. Credit: <a class=\"rId11\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Cladograma_dos_Dom%C3%ADnios_e_Reinos.png\">Cladograma dos Dominios e Reinos<\/a> by <a class=\"rId12\" href=\"https:\/\/commons.wikimedia.org\/wiki\/User:MarceloTeles\">MarceloTeles<\/a> has been modified (English labels replace Portuguese) and is under a <a class=\"rId13\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/deed.en\">CC BY-SA 4.0 License<\/a>..<\/figcaption><\/figure>\n<p class=\"import-Normal\">Looking at the common sequences in modern genomes, we can even make educated guesses about the likely genetic sequence of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1446\"><strong>Last Universal Common Ancestor (LUCA)<\/strong><\/a> of all living things. Through a wondrous series of mechanisms and events over nearly four billion years, that ancient single-celled organism gave rise to the rich diversity of species that fill the lands, seas, and skies of our planet. This chapter explores the mechanisms by which that amazing transformation occurred and considers some of the crucial scientific experiments that shaped our current understanding of the evolutionary process.<\/p>\n<h2 class=\"import-Normal\">Population Genetics<\/h2>\n<h3 class=\"import-Normal\"><strong>Defining Populations and the Variations <\/strong><strong>w<\/strong><strong>ithin Them<\/strong><\/h3>\n<p class=\"import-Normal\">One of the major breakthroughs in understanding the mechanisms of evolutionary change came with the realization that evolution takes place at the level of populations, not within individuals. In the biological sciences, a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1454\"><strong>p<\/strong><strong>opulation<\/strong><\/a> is defined as a group of individuals of the same <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1456\"><strong>species<\/strong><\/a> who are geographically near enough to one another that they can breed and produce new generations of individuals.<\/p>\n<p class=\"import-Normal\">For the purpose of studying evolution, we recognize populations by their even smaller units: genes. Remember, a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1458\"><strong>gene<\/strong><\/a> is the basic unit of information that encodes the proteins needed to grow and function as a living organism. Each gene can have multiple <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_738\">alleles<\/a><\/strong>, or variants\u2014each of which may produce a slightly different protein. Each individual, for genetic inheritance purposes, carries a collection of genes that can be passed down to future generations. For this reason, in population genetics, we think of populations as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1462\"><strong>gene pools<\/strong><\/a>, which refers to the entire collection of genetic material in a breeding community that can be passed on from one generation to the next.<\/p>\n<p class=\"import-Normal\">For genes carried on our human chromosomes (our nuclear DNA), we inherit two copies of each, one from each parent. This means we may carry two of the same alleles (a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1464\"><strong>homozygous genotype<\/strong><\/a>) or two different alleles (a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1466\"><strong>heterozygous<\/strong> <strong>genotype<\/strong><\/a>) for each nuclear gene.<\/p>\n<h3 class=\"import-Normal\"><strong>Defining Evolution <\/strong><\/h3>\n<p class=\"import-Normal\">In order to understand evolution, it\u2019s crucial to remember that evolution is always studied at the population level. Also, if a population were to stay exactly the same from one generation to the next, it would not be evolving. So evolution requires both a population of breeding individuals and some kind of a genetic change occurring within it. Thus, the simple definition of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1468\"><strong>evolution<\/strong><\/a> is a change in the allele frequencies in a population over time. What do we mean by allele frequencies? <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1470\"><strong>Allele frequencies<\/strong> <\/a>refer to the ratio, or percentage, of one allele (one variant of a gene) compared to the other alleles for that gene within the study population (Figure 5.2). By contrast, <strong>genotype frequencies<\/strong> are the ratios or percentages of the different homozygous and heterozygous genotypes in the population. Because we carry two alleles per <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_736\">genotype<\/a><\/strong>, the total count of alleles in a population will usually be exactly double the total count of genotypes in the same population (with the exception being rare cases in which an individual carries a different number of chromosomes than the typical two; e.g., Down syndrome results when a child carries three copies of Chromosome 21).<\/p>\n<figure style=\"width: 652px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image2.jpg\" alt=\"Genotypes are represented as combinations of alleles and allele frequencies.\" width=\"652\" height=\"883\" \/><figcaption class=\"wp-caption-text\">Figure 5.2: Population evolution can be measured by allele frequency changes. This diagram illustrates the differences between genotype frequencies and allele frequencies, as well as how they can be measured in a population of snapdragon flowers. The lower portion of the diagram also depicts how evolution is recognized as allele frequencies change in a population over time. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available<\/a>. Credit: Population evolution original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Katie Nelson and Beth Shook is a collective work under a <a class=\"rId15\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\">CC BY-NC 4.0 License<\/a>. [Includes <a class=\"rId16\" href=\"https:\/\/pixabay.com\/vectors\/snapdragon-flower-pink-lilac-plant-146850\/\">Snapdragon-flower-pink-lilac<\/a> by <a class=\"rId17\" href=\"https:\/\/pixabay.com\/users\/openclipart-vectors-30363\/\">OpenClipart-Vectors<\/a>, <a class=\"rId18\" href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/cc0\/\">public domain (CC0)<\/a> under a <a class=\"rId19\" href=\"https:\/\/pixabay.com\/service\/terms\/\">Pixabay License<\/a>.]<\/figcaption><\/figure>\n<h2 class=\"import-Normal\">The Forces of Evolution<\/h2>\n<p class=\"import-Normal\">Today, we recognize that evolution takes place through a combination of mechanisms: mutation, genetic drift, gene flow, and natural selection. These mechanisms are called the \u201cforces of evolution\u201d; together they account for all the genotypic variation observed in the world today. Keep in mind that each of these forces was first defined and then tested\u2014and retested\u2014through the experimental work of the many scientists who contributed to the Modern Synthesis.<\/p>\n<h3 class=\"import-Normal\"><strong>Mutation<\/strong><\/h3>\n<p class=\"import-Normal\">The first force of evolution we will discuss is mutation, and for good reason: mutation is the original source of all the genetic variation found in every living thing. Imagine all the way back in time to the very first single-celled organism, floating in Earth\u2019s primordial sea. Based on what we observe in simple, single-celled organisms today, that organism probably spent its lifetime absorbing nutrients and dividing to produce cloned copies of itself. While the numbers of individuals in that population would have grown (as long as the environment was favourable), nothing would have changed in that perfectly cloned population. There would not have been variety among the individuals. It was only through a copying error\u2014the introduction of a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1474\"><strong>mutation<\/strong><\/a>, or change, into the genetic code\u2014that new alleles were introduced into the population.<br style=\"clear: both\" \/><br style=\"clear: both\" \/>After many generations have passed in our primordial population, mutations have created distinct chromosomes. The cells are now amoeba-like, larger than many of their tiny bacterial neighbours, who have long since become their favourite source of nutrients. Without mutation to create this diversity, all living things would still be identical to LUCA, our universal ancestor (Figure 5.3).<\/p>\n<figure style=\"width: 663px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image3-2.png\" alt=\"Universal Ancestor linked to the Eukarya branch.\" width=\"663\" height=\"338\" \/><figcaption class=\"wp-caption-text\">Figure 5.3: Key mutational differences between Last Universal Common Ancestor and an amoeba-like primordial cell. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available<\/a>. Credit<strong>: <\/strong>Key differences between LUCA and a primordial cell original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Andrea J. Alveshere is a collective work under a <a class=\"rId21\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\">CC BY-NC-SA 4.0 License<\/a>. [Includes <a class=\"rId22\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Cladograma_dos_Dom%C3%ADnios_e_Reinos.png\">Cladograma dos Dominios e Reinos<\/a> by <a class=\"rId23\" href=\"https:\/\/commons.wikimedia.org\/wiki\/User:MarceloTeles\">MarceloTeles<\/a> (cropped, labels and colour changed), <a class=\"rId24\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/deed.en\">CC BY-SA 4.0<\/a><a class=\"rId25\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/deed.en\">; <\/a><a class=\"rId26\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Amoeba_proteus_TK-UT.svg\">Amoeba Proteus TK-UT<\/a> by <a class=\"rId27\" href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Nefronus\">Tom\u00e1\u0161 Kebert<\/a> and <a class=\"rId28\" href=\"https:\/\/www.umimeto.org\/\">umimeto.org<\/a> (cropped and colour changed), <a class=\"rId29\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/deed.en\">CC BY-SA 4.0<\/a>.]<\/figcaption><\/figure>\n<p class=\"import-Normal\">When we think of genetic mutation, we often first think of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1476\">deleterious mutations<\/a><\/strong>\u2014the ones associated with negative effects such as the beginnings of cancers or heritable disorders. The fact is, though, that every genetic adaptation that has helped our ancestors survive since the dawn of life is directly due to <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1478\">beneficial mutations<\/a><\/strong>\u2014changes in the DNA that provided some sort of advantage to a given population at a particular moment in time. For example, a beneficial mutation allowed chihuahuas and other tropical-adapted dog breeds to have much thinner fur coats than their cold-adapted cousins the northern wolves, malamutes, and huskies.<\/p>\n<figure style=\"width: 320px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image4-1-1.png\" alt=\"UV radiation damages nucleotides in DNA.\" width=\"320\" height=\"248\" \/><figcaption class=\"wp-caption-text\">Figure 5.4: A crosslinking mutation in which a UV photon induces a bond between two thymine bases. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available<\/a>. Credit<strong>: <\/strong><a class=\"rId31\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-3\/\">UV-induced Thymine dimer mutation (Figure 4.6)<\/a> original to <a class=\"rId32\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a class=\"rId33\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Every one of us has genetic mutations. Yes, even you. The DNA in some of your cells today differs from the original DNA that you inherited when you were a tiny, fertilized egg. Mutations occur all the time in the cells of our skin and other organs, due to chemical changes in the nucleotides. Exposure to the UV radiation in sunlight is one common cause of skin mutations. Interaction with UV light causes <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1480\"><strong>UV crosslinking<\/strong><\/a>, in which adjacent thymine bases bind with one another (Figure 5.4). Many of these mutations are detected and corrected by <strong>DNA repair mechanisms<\/strong>, enzymes that patrol and repair DNA in living cells, while other mutations may cause a new freckle or mole or, perhaps, an unusual hair to grow. For people with the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1484\">autosomal recessive<\/a><\/strong> disease <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1486\"><strong>xeroderma pigmentosum<\/strong><\/a>, these repair mechanisms do not function correctly, resulting in a host of problems especially related to sun exposure, including severe sunburns, dry skin, heavy freckling, and other pigment changes.<\/p>\n<p class=\"import-Normal\">Most of our mutations exist in <strong>somatic<\/strong> cells, which are the cells of our organs and other body tissues. Those will not be passed onto future generations and so will not affect the population over time. Only mutations that occur in the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_686\">gametes<\/a><\/strong>, the reproductive cells (i.e., the sperm or egg cells), will be passed onto future generations. When a new mutation pops up at random in a family lineage, it is known as a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1490\"><strong>spontaneous mutation<\/strong><\/a>. If the individual born with this spontaneous mutation passes it on to his offspring, those offspring receive an <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1492\">inherited mutation<\/a><\/strong>. Geneticists have identified many classes of mutations and the causes and effects of many of these.<\/p>\n<h4 class=\"import-Normal\"><em>Point Mutations<\/em><\/h4>\n<p class=\"import-Normal\">A <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1494\">point mutation<\/a><\/strong> is a single-letter (single-nucleotide) change in the genetic code resulting in the substitution of one nucleic acid base for a different one. As you learned in Chapter 4, the DNA code in each gene is translated through three-letter \u201cwords\u201d known as <strong>codons<\/strong>. So depending on how the point mutation changes the \u201cword,\u201d the effect it will have on the protein may be major or minor or may make no difference at all.<\/p>\n<p class=\"import-Normal\">If a mutation does not change the resulting protein, then it is called a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1496\">synonymous mutation<\/a><\/strong>. Synonymous mutations do involve a letter (nucleic acid) change, but that change results in a codon that codes for the same \u201cinstruction\u201d (the same amino acid or stop code) as the original codon. Mutations that do cause a change in the protein are known as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1498\"><strong>nonsynonymous mutations<\/strong>.<\/a> Nonsynonymous mutations may change the resulting protein\u2019s amino acid sequence by altering the DNA sequence that encodes the mRNA or by changing how the mRNA is spliced prior to translation (refer to Chapter 4 for more details).<\/p>\n<h4 class=\"import-Normal\"><em>Insertions and Deletions<\/em><\/h4>\n<p class=\"import-Normal\">In addition to point mutations, another class of mutations are <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1500\"><strong>insertions<\/strong><\/a> and <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1504\">deletions<\/a><\/strong>, or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1502\"><strong>indels<\/strong><\/a>, for short. As the name suggests, these involve the addition (insertion) or removal (deletion) of one or more coding sequence letters (nucleic acids). These typically first occur as an error in DNA replication, wherein one or more nucleotides are either duplicated or skipped in error. Entire codons or sets of codons may also be removed or added if the indel is a multiple of three nucleotides.<\/p>\n<p class=\"import-Normal\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1506\"><strong>Frameshift<\/strong> <strong>mutations<\/strong><\/a> are types of indels that involve the insertion or deletion of any number of nucleotides that is not a multiple of three (e.g., adding one or two extra letters to the code). Because these indels are not consistent with the codon numbering, they \u201cshift the reading frame,\u201d causing all the codons beyond the mutation to be misread. Like point mutations, small indels can also disrupt splice sites.<\/p>\n<p class=\"import-Normal\"><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1508\">Transposable elements<\/a><\/strong>, or <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1510\">transposons<\/a><\/strong>, are fragments of DNA that can \u201cjump\u201d around in the genome. There are two types of transposons: <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1512\">retrotransposons<\/a><\/strong> are transcribed from DNA into RNA and then \u201creverse transcribed,\u201d to insert the copied sequence into a new location in the DNA, and<strong> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1514\">DNA transposons<\/a><\/strong>, which do not involve RNA. DNA transposons are clipped out of the DNA sequence itself and inserted elsewhere in the genome. Because transposable elements insert themselves into existing DNA sequences, they are frequent gene disruptors. At certain times, and in certain species, it appears that transposons became very active, likely accelerating the mutation rate (and thus, the genetic variation) in those populations during the active periods.<\/p>\n<h4 class=\"import-Normal\"><em>Chromosomal Alterations <\/em><\/h4>\n<p class=\"import-Normal\">The final major category of genetic mutations are changes at the chromosome level: crossover events, nondisjunction events, and translocations. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1516\"><strong>Crossover events<\/strong> <\/a> occur when DNA is swapped between homologous chromosomes while they are paired up during meiosis I. Crossovers are thought to be so common that some DNA swapping may happen every time chromosomes go through meiosis I. Crossovers don\u2019t necessarily introduce new alleles into a population, but they do make it possible for new combinations of alleles to exist on a single chromosome that can be passed to future generations. This also enables new combinations of alleles to be found within siblings who share the same parents. Also, if the fragments that cross over don\u2019t break at exactly the same point, they can cause genes to be deleted from one of the homologous chromosomes and duplicated on the other.<\/p>\n<p class=\"import-Normal\"><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1518\">Nondisjunction events<\/a><\/strong> occur when the homologous chromosomes (in meiosis I) or sister chromatids (in meiosis II and mitosis) fail to separate after pairing. The result is that both chromosomes or chromatids end up in the same daughter cell, leaving the other daughter cell without any copy of that chromosome (Figure 5.5). Most nondisjunctions at the gamete level are fatal to the embryo. The most widely known exception is Trisomy 21, or Down syndrome, which results when an embryo inherits three copies of Chromosome 21: two from one parent (due to a nondisjunction event) and one from the other (Figure 5.6). <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1520\">Trisomies<\/a> <\/strong>(triple chromosome conditions) of Chromosomes 18 (Edwards syndrome) and 13 (Patau syndrome) are also known to result in live births, but the children usually have severe complications and rarely survive beyond the first year of life.<\/p>\n<figure style=\"width: 601px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image5.jpg\" alt=\"Egg cell undergoes normal meiosis and nondisjunction in meisosis 1.\" width=\"601\" height=\"391\" \/><figcaption class=\"wp-caption-text\">Figure 5.5: Illustration of an egg cell (oocyte) undergoing normal meiosis 1, resulting in a diploid daughter cell, compared to an egg cell undergoing nondisjunction during meiosis 1, resulting in a trisomy in the daughter cell. Credit: <a class=\"rId35\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Trisomy_due_to_nondisjunction_in_maternal_meiosis_1.png\">Trisomy due to nondisjunction in maternal meiosis 1<\/a> by Wpeissner has been modified (labels deleted by Katie Nelson) and is under a <a class=\"rId36\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\">CC BY-NC-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<figure style=\"width: 316px\" class=\"wp-caption alignright\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image6-1.jpg\" alt=\"A young woman in a blue polo shirt smiles at the camera.\" width=\"316\" height=\"364\" \/><figcaption class=\"wp-caption-text\">Figure 5.6: Amy Bockerstette, a competitive golfer and disabilities advocate, also has Down Syndrome. Credit: <a class=\"rId38\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Amy_Bockerstette_Headshot.jpg\">Amy Bockerstette Headshot<\/a> by Bucksgrandson is under a <a class=\"rId39\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Sex chromosome trisomies (XXX, XXY, XYY) and X chromosome <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1522\"><strong>monosomies<\/strong> <\/a>(inheritance of an X chromosome from one parent and no sex chromosome from the other) are also survivable and fairly common. The symptoms vary but often include atypical sexual characteristics, either at birth or at puberty, and often result in sterility. The X chromosome carries unique genes that are required for survival; therefore, Y chromosome monosomies are incompatible with life.<\/p>\n<p class=\"import-Normal\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1524\"><strong>Chromosomal translocations<\/strong><\/a> involve transfers of DNA between nonhomologous chromosomes. This may involve swapping large portions of two or more chromosomes. The exchanges of DNA may be balanced or unbalanced. In <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1526\"><strong>balanced translocations<\/strong><\/a>, the genes are swapped, but no genetic information is lost. In <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1528\">unbalanced translocations<\/a><\/strong>, there is an unequal exchange of genetic material, resulting in duplication or loss of genes. Translocations result in new chromosomal structures called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1530\"><strong>derivative chromosomes<\/strong><\/a>, because they are derived or created from two different chromosomes<em>. <\/em>Translocations are often found to be linked to cancers and can also cause infertility. Even if the translocations are balanced in the parent, the embryo often won\u2019t survive unless the baby inherits both of that parent\u2019s derivative chromosomes (to maintain the balance).<\/p>\n<h3 class=\"import-Normal\"><strong>Genetic Drift<\/strong><\/h3>\n<p class=\"import-Normal\">The second force of evolution is commonly known as genetic drift. This is an unfortunate misnomer, as this force actually involves the drifting of alleles, not genes. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1532\"><strong>Genetic <\/strong><strong>d<\/strong><strong>rift<\/strong><\/a> refers to <em>random<\/em> changes (\u201cdrift\u201d) in allele frequencies from one generation to the next. The genes are remaining constant within the population; it is only the alleles of the genes that are changing in frequency. The random nature of genetic drift is a crucial point to understand: it specifically occurs when none of the variant alleles confer an advantage.<\/p>\n<figure style=\"width: 368px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image7-2.png\" alt=\"A smooth cell has a gently curving exterior surface, and a ruffled cell has undulating surface.\" width=\"368\" height=\"215\" \/><figcaption class=\"wp-caption-text\">Figure 5.7: Smooth and ruffled amoeba-like cells. Credit: Smooth and ruffled amoeba-like cells original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Andrea J. Alveshere is a collective work under a <a class=\"rId41\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\">CC BY-NC-SA 4.0 License<\/a>. [Includes <a class=\"rId42\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Amoeba_proteus_TK-UT.svg\">Amoeba Proteus TK-UT<\/a> by <a class=\"rId43\" href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Nefronus\">Tom\u00e1\u0161 Kebert<\/a> and <a class=\"rId44\" href=\"https:\/\/www.umimeto.org\/\">umimeto.org<\/a> (modified), <a class=\"rId45\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/deed.en\">CC BY-SA 4.0<\/a>.]<\/figcaption><\/figure>\n<p class=\"import-Normal\">Let\u2019s imagine far back in time, again, to that ancient population of amoeba-like cells, subsisting and occasionally dividing, in the primordial sea. A mutation occurs in one of the cells that changes the texture of the cell membrane from a relatively smooth surface to a highly ruffled one (Figure 5.7). This has absolutely no effect on the cell\u2019s quality of life or ability to reproduce. In fact, eyes haven\u2019t evolved yet, so no one in the world at the time would even notice the difference. The cells in the population continue to divide, and the offspring of the ruffled cell inherit the ruffled membrane. The frequency (percentage) of the ruffled allele in the population, from one generation to the next, will depend entirely on how many offspring that first ruffled cell ends up having, and the random events that might make the ruffled alleles more common or more rare (such as population bottlenecks and founder effects, which are discussed below).<\/p>\n<h4 class=\"import-Normal\"><em>Sexual Reproduction and Random Inheritance<\/em><\/h4>\n<p class=\"import-Normal\">Tracking alleles gets a bit more complicated in our primordial cells when, after a number of generations, a series of mutations have created populations that reproduce sexually. These cells now must go through an extra round of cell division (meiosis) to create haploid gametes. The combination of two gametes is now required to produce each new diploid offspring.<\/p>\n<figure style=\"width: 262px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image8-1.png\" alt=\"A Punnett square with ruffled and smooth cells.\" width=\"262\" height=\"262\" \/><figcaption class=\"wp-caption-text\">Figure 5.8: A Punnett square demonstrating the sexual inheritance pattern of ruffled (dominant) and smooth amoeba-like primordial cells. Credit: Punnett square of primordial cells original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Andrea J. Alveshere is a collective work under a <a class=\"rId47\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\">CC BY-NC-SA 4.0 License<\/a>. [Includes <a class=\"rId48\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Amoeba_proteus_TK-UT.svg\">Amoeba Proteus TK-UT<\/a> by <a class=\"rId49\" href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Nefronus\">Tom\u00e1\u0161 Kebert<\/a> and <a class=\"rId50\" href=\"https:\/\/www.umimeto.org\/\">umimeto.org<\/a> (modified), <a class=\"rId51\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/deed.en\">CC BY-SA 4.0<\/a>; <a class=\"rId52\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Punnett_hetero_x_hetero.svg\">Punnett Hetero x Hetero<\/a> by <a class=\"rId53\" href=\"https:\/\/commons.wikimedia.org\/w\/index.php?title=User:Purpy_Pupple&amp;redirect=no\">Purpy Pupple<\/a> (modified), <a class=\"rId54\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/deed.en\">CC BY-SA 3.0<\/a>].<\/figcaption><\/figure>\n<p class=\"import-Normal\">In the earlier population, which reproduced via <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1534\">asexual reproduction<\/a><\/strong>, a cell either carried the smooth allele or the ruffled allele. With <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1536\">sexual reproduction<\/a><\/strong>, a cell inherits one allele from each parent, so there are homozygous cells that contain two smooth alleles, homozygous cells that contain two ruffled alleles, and heterozygous cells that contain one of each allele (Figure 5.8). If the new, ruffled allele happens to be dominant (and we\u2019ll imagine that it is), the heterozygotes will have ruffled cell <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1238\"><strong>phenotypes<\/strong><\/a> but also will have a 50\/50 chance of passing on a smooth allele to each offspring. As long as neither phenotype (ruffled nor smooth) provides any advantage over the other, the variation in the population from one generation to the next will remain completely random.<\/p>\n<p class=\"import-Normal\">In sexually reproducing populations (including humans and many other animals and plants in the world today), that 50\/50 chance of inheriting one or the other allele from each parent plays a major role in the random nature of genetic drift.<\/p>\n<h4 class=\"import-Normal\"><em>Population Bottlenecks <\/em><\/h4>\n<p class=\"import-Normal\">A <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1538\"><strong>population bottleneck<\/strong><\/a> occurs when the number of individuals in a population drops dramatically due to some random event. The most obvious, familiar examples are natural disasters. Tsunamis and hurricanes devastating island and coastal populations and forest fires and river floods wiping out populations in other areas are all too familiar. When a large portion of a population is randomly wiped out, the allele frequencies (i.e., the percentages of each allele) in the small population of survivors are often much different from the frequencies in the predisaster, or \u201cparent,\u201d population.<\/p>\n<p class=\"import-Normal\">If such an event happened to our primordial ocean cell population\u2014perhaps a volcanic fissure erupted in the ocean floor and only the cells that happened to be farthest from the spewing lava and boiling water survived\u2014we might end up, by random chance, with a surviving population that had mostly ruffled alleles, in contrast to the parent population, which had only a small percentage of ruffles (Figure 5.9).<\/p>\n<figure style=\"width: 665px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image9-2.png\" alt=\"Ruffled and smooth cells experience population bottleneck when a lava flow divides the populations.\" width=\"665\" height=\"332\" \/><figcaption class=\"wp-caption-text\">Figure 5.9: Illustration of a population of amoeba-like cells shifting from primarily smooth phenotypes (at left) to mostly ruffled phenotypes due to eruption of a volcanic fissure (at right) that exterminated the nearest cells. Credit: Population of amoeba-like cells and volcanic fissure original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Andrea J. Alveshere is a collective work under a <a class=\"rId56\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\">CC BY-NC-SA 4.0 License<\/a>. [Includes <a class=\"rId57\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Amoeba_proteus_TK-UT.svg\">Amoeba Proteus TK-UT<\/a> by <a class=\"rId58\" href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Nefronus\">Tom\u00e1\u0161 Kebert<\/a> and <a class=\"rId59\" href=\"https:\/\/www.umimeto.org\/\">umimeto.org<\/a> (modified), <a class=\"rId60\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/deed.en\">CC BY-SA 4.0<\/a>.]<\/figcaption><\/figure>\n<p class=\"import-Normal\">One of the most famous examples of a population bottleneck is the prehistoric disaster that led to the extinction of dinosaurs, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1540\"><strong>Cretaceous\u2013Paleogene <\/strong><strong>extinction<\/strong><\/a> event (often abbreviated K\u2013Pg; previously K-T). This occurred approximately 66 million years ago. Dinosaurs and all their neighbours were going about their ordinary routines when a massive asteroid zoomed in from space and crashed into what is now the Gulf of Mexico, creating an impact so enormous that populations within hundreds of miles of the crash site were likely immediately wiped out. The skies filled with dust and debris, causing temperatures to plummet worldwide. It\u2019s estimated that 75% of the world\u2019s species went extinct as a result of the impact and the deep freeze that followed (Jablonski and Chaloner 1994).<\/p>\n<figure style=\"width: 399px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image10-2.png\" alt=\" A rat-like creature sits atop a dinosaur, raising a fist in a victorious gesture.\" width=\"399\" height=\"323\" \/><figcaption class=\"wp-caption-text\">Figure 5.10: The Cretaceous\u2013Paleogene extinction event, which led to the fall of the dinosaurs and rise of the mammals. Credit: <a class=\"rId62\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-3\/\">The<\/a> <a class=\"rId64\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-3\/\">Cretaceous\u2013Paleogene extinction event (Figure 4.12)<\/a> original to <a class=\"rId65\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a class=\"rId66\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">The populations that emerged from the K-Pg extinction were markedly different from their pre-disaster communities. Surviving mammal populations expanded and diversified, and other new creatures appeared. The ecosystems of Earth were filled with new organisms and have never been the same (Figure 5.10).<\/p>\n<p class=\"import-Normal\">Much more recently in geological time, during the colonial period, many human populations experienced bottlenecks as a result of the fact that imperial powers were inclined to slaughter communities who were reluctant to give up their lands and resources. This effect was especially profound in the Americas, where Indigenous populations faced the compounded effects of brutal warfare, exposure to new bacteria and viruses (against which they had no immunity), and ultimately segregation on resource-starved reservations. The populations in Europe, Asia, and Africa had experienced regular gene flow during the 10,000-year period in which most kinds of livestock were being domesticated, giving them many generations of experience building up immunity against zoonotic diseases (those that can pass from animals to humans). In contrast, the residents of the Americas had been almost completely isolated during those millennia, so all these diseases swept through the Americas in rapid succession, creating a major loss of genetic diversity in the Indigenous American population. It is estimated that between 50% and 95% of the Indigenous American populations died during the first decades after European contact, around 500 years ago (Livi-Bacci 2006).<\/p>\n<p class=\"import-Normal\">An urgent health challenge facing humans today involves human-induced population bottlenecks that produce antibiotic-resistant bacteria. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1451\"><strong>Antibiotics<\/strong> <\/a>are medicines prescribed to treat bacterial infections. The typical prescription includes enough medicine for ten days. People often feel better much sooner than ten days and sometimes decide to quit taking the medicine ahead of schedule. This is often a big mistake. The antibiotics have quickly killed off a large percentage of the bacteria\u2014enough to reduce the symptoms and make you feel much better. However, this has created a bacterial population bottleneck. There are usually a small number of bacteria that survive those early days. If you take the medicine as prescribed for the full ten days, it\u2019s quite likely that there will be no bacterial survivors. If you quit early, though, the survivors\u2014who were the members of the original population who were most resistant to the antibiotic\u2014will begin to reproduce again. Soon the infection will be back, possibly worse than before, and now all of the bacteria are resistant to the antibiotic that you had been prescribed.<\/p>\n<p class=\"import-Normal\">Other activities that have contributed to the rise of antibiotic-resistant bacteria include the use of antibacterial cleaning products and the inappropriate use of antibiotics as a preventative measure in livestock or to treat infections that are viral instead of bacterial (viruses do not respond to antibiotics). In 2017, the World Health Organization published a list of twelve antibiotic-resistant pathogens that are considered top priority targets for the development of new antibiotics (World Health Organization 2017).<\/p>\n<div class=\"textbox shaded\" style=\"background: var(--lightblue)\">\n<h2>Dig Deeper: The North American Elephant Seal: Thriving Bottleneck Populations That Still Face Genetic Defects<\/h2>\n<p>In 1892, the Northern Elephant Seal underwent a severe population bottleneck caused by commercial hunting, reducing the species to an estimated 20 individuals at the time. This drastic decline led to a substantial loss of genetic diversity\u2013a common consequence of extreme population bottlenecks (Hoelzel Et al., 2024 &amp; Weber Et al., 2000). While the population has since recovered to over 200,000 individuals, its genetic variability remains significantly low. Analyses of genetic markers, including allozymes, mitochondrial DNA, and microsatellites, consistently reflect this reduced diversity (Hoelzel Et al., 2024). Comparative studies further underscore this loss by highlighting the higher genetic variation observed in the Southern Elephant Seal, which did not experience similar population constraints (2024).<\/p>\n<figure style=\"width: 386px\" class=\"wp-caption alignleft\"><img src=\"https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/4\/48\/Elephant_seals_at_Ano_Nuevo_%2891577%29.jpg\/250px-Elephant_seals_at_Ano_Nuevo_%2891577%29.jpg\" alt=\"File:Elephant seals at Ano Nuevo (91577).jpg\" width=\"386\" height=\"295\" \/><figcaption class=\"wp-caption-text\">Figure 5.11 A male northern elephant seal (Mirounga angustirostris) with two pups at Ano Nuevo State Park. Credit: Elephant seals at Ano Nuevo by Rhododendrites is under <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\" target=\"_blank\" rel=\"noopener\">Creative Commons Attribution-Share Alike 4.0<\/a>.<\/figcaption><\/figure>\n<p>In a 2024 study for Nature, Ecology, and Evolution, Hoelzel and colleagues sequenced 260 modern and 8 historical genomes of the northern elephant seal. This comparison revealed a decrease in average heterozygosity from 0.00142 before the bottleneck to 0.000176 in the contemporary population, confirming the decline in genetic variation (2024). Hoelzel\u2019s mitogenome tree further illustrates this loss, revealing only two significant lineages remaining post-bottleneck, with limited diversity within each. Among the issues of diversity, the population has shown an increased number of loss-of-function (LOF) alleles, suggesting that increased inbreeding has amplified the frequency of these detrimental alleles; this reduced genetic diversity negatively affects both male and female reproductive fitness. Females who practiced repetitive inbreeding had higher LOF alleles and subsequently weaned fewer pups per year over their lifetime, while male reproductive success was linked to specific LOF loci associated with sperm production (2024). Hoelzel uses the example of \u201cAlpha-Male M12\u201d\u2013known for low paternity success despite frequent copulations\u2013which was homozygous for non-functional versions of four out of five LOF loci related to sperm function (2024, p. 688). The species' mating system, characterized by extreme polygyny, further exacerbates the loss of genetic variation even with countless copulatory partners<\/p>\n<p>Prior research published in Current Biology presents an empirical genetic assessment of this population bottleneck, highlighting its long-term genetic consequences, particularly the loss of mitochondrial diversity (Weber et al., 2000). In this research, Weber and colleagues note that random lineage sampling during the bottleneck led to the persistence of specific genetic variants by chance rather than through natural selection (2000). This research emphasizes that the loss of diversity poses potential future genetic vulnerabilities for the seals, and that further studies are crucial for understanding the full scope of these impacts on the seals' overall fitness (2000). In 2024, the work led by Hoelzen and company provided the missing data that the previous study had left unanswered. Their previously explored findings indicate that, although the seals have recovered in numbers, their genetic resilience remains compromised, leaving the population more vulnerable to future environmental pressures, such as climate change or resource shortages (Hoelzel Et al., 2024). Ultimately, while the population's size remains stable, the genetic consequences of the bottleneck indicate that past stochastic events continue to influence the seals' long-term fitness and adaptability.<\/p>\n<p>This research indicates that the historical bottleneck continues to affect the seals' health and fitness, despite the population's recovery. Limited genetic diversity and the persistence of harmful alleles due to inbreeding have continued to handicap the species' ability to thrive in environmental challenges such as climate change and resource fluctuations (2024). This emphasizes the importance of incorporating genetic factors into conservation strategies, as populations that have rebounded may still harbour long-term genetic weaknesses. Moreover, the elephant seal\u2019s history serves as a powerful example of how human actions \u2014such as overhunting \u2014 can have long-lasting impacts on biodiversity, reinforcing the importance of understanding human-environment interactions in ecological and conservation contexts.<\/p>\n<\/div>\n<h4 class=\"import-Normal\"><em>Founder Effects<\/em><\/h4>\n<p class=\"import-Normal\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1452\"><strong>Founder effects<\/strong><\/a> occur when members of a population leave the main or \u201cparent\u201d group and form a new population that no longer interbreeds with the other members of the original group. Similar to survivors of a population bottleneck, the newly founded population often has allele frequencies that are different from the original group. Alleles that may have been relatively rare in the parent population can end up being very common due to the founder effect. Likewise, recessive traits that were seldom seen in the parent population may be seen frequently in the descendants of the offshoot population.<\/p>\n<p class=\"import-Normal\">One striking example of the founder effect was first noted in the Dominican Republic in the 1970s. During a several-year period, eighteen children who had been born with female genitalia and raised as girls suddenly grew penises at puberty. This culture tended to value sons over daughters, so these transitions were generally celebrated. They labeled the condition <em><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1453\">guevedoces<\/a><\/strong><\/em>, which translates to \u201cpenis at twelve,\u201d due to the average age at which this occurred. Scientists were fascinated by the phenomenon.<\/p>\n<p class=\"import-Normal\">Genetic and hormonal studies revealed that the condition, scientifically termed <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1454\">5-alpha reductase deficiency<\/a>,<\/strong> is an autosomal recessive syndrome that manifests when a child having both X and Y sex chromosomes inherits two nonfunctional (mutated) copies of the <em>SRD5A2 <\/em>gene (Imperato-McGinley &amp; Zhu 2002). These children develop testes internally, but the 5-alpha reductase 2 steroid, which is necessary for development of male genitals in babies, is not produced. In absence of this male hormone, the baby develops female-looking genitalia (in humans, \u201cfemale\u201d is the default infant body form, if the full set of the necessary male hormones are not produced). At puberty, however, a different set of male hormones are produced by other fully functional genes. These hormones complete the male genital development that did not happen in infancy. This condition became quite common in the Dominican Republic during the 1970s due to founder effect\u2014that is, the mutated <em>SRD5A2<\/em> gene happened to be much more common among the Dominican Republic\u2019s founding population than in the parent populations. (The Dominican population derives from a mixture of Indigenous Americans [Taino] peoples, West Africans, and Western Europeans.) Five-alpha reductase syndrome has since been observed in other small, isolated populations around the world.<\/p>\n<p class=\"import-Normal\">Founder effect is closely linked to the concept of inbreeding, which in population genetics does not necessarily mean breeding with immediate family relatives. Instead, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1455\"><strong>inbreeding<\/strong> <\/a> refers to the selection of mates exclusively from within a small, closed population\u2014that is, from a group with limited allelic variability. This can be observed in small, physically isolated populations but also can happen when cultural practices limit mates to a small group. As with the founder effect, inbreeding increases the risk of inheriting two copies of any nonfunctional (mutant) alleles.<\/p>\n<p class=\"import-Normal\">The Amish in the United States are a population that, due to their unique history and cultural practices, emerged from a small founding population and have tended to select mates from within their groups. The <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1456\">Old Order Amish<\/a><\/strong> population of Lancaster County, Pennsylvania, has approximately 50,000 current members, all of whom can trace their ancestry back to a group of approximately 80 individuals. This small founding population immigrated to the United States from Switzerland in the mid-1700s to escape religious persecution. Since the Amish keep to themselves and almost exclusively select mates from within their own communities, they have more recessive traits compared to their parent population.<\/p>\n<figure style=\"width: 441px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image11-1.jpg\" alt=\"One individual\u2019s hands with six fingers.\" width=\"441\" height=\"331\" \/><figcaption class=\"wp-caption-text\">Figure 5.12: A person displaying polydactyly. Credit: <a class=\"rId68\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:6_Finger.JPG\">6 Finger<\/a> by Wilhelmy is under a <a class=\"rId69\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">One of the genetic conditions that has been observed much more frequently in the Lancaster County Amish population is <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1457\">Ellis-van Creveld syndrome<\/a><\/strong>, which is an autosomal recessive disorder characterized by short stature (dwarfism), polydactyly (the development of more than five digits [fingers or toes] on the hands or feet], abnormal tooth development, and heart defects (Figure 5.12). Among the general world population, Ellis-van Creveld syndrome is estimated to affect approximately 1 in 60,000 individuals; among the Old Order Amish of Lancaster County, the rate is estimated to be as high as 1 in every 200 births (D\u2019Asdia Et al. 2013).<\/p>\n<p class=\"import-Normal\">One important insight that has come from the study of founder effects is that a limited gene pool carries a much higher risk for genetic diseases. Genetic diversity in a population greatly reduces these risks.<\/p>\n<h3 class=\"import-Normal\"><strong>Gene Flow<\/strong><\/h3>\n<p class=\"import-Normal\">The third force of evolution is traditionally called gene flow. As with genetic drift, this is a misnomer, because it refers to flowing alleles, not genes. (All members of the same species share the same genes; it is the alleles of those genes that may vary.) <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1459\"><strong>Gene <\/strong><strong>f<\/strong><strong>low<\/strong> <\/a> refers to the movement of alleles from one population to another. In most cases, gene flow can be considered synonymous with migration.<\/p>\n<p class=\"import-Normal\">Returning again to the example of our primordial cell population, let\u2019s imagine that, after the volcanic fissure opened up in the ocean floor, wiping out the majority of the parent population, two surviving populations developed in the waters on opposite sides of the fissure. Ultimately, the lava from the fissure cooled into a large island that continued to provide a physical barrier between the populations (Figure 5.13).<\/p>\n<figure style=\"width: 685px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image12-2.png\" alt=\"An illustration of gene flow.\" width=\"685\" height=\"342\" \/><figcaption class=\"wp-caption-text\">Figure 5.13: Smooth and predominantly ruffled amoeba-like populations separated by a volcanic eruption (at left) and an island (at right) with unidirectional gene flow moving from east to west with ocean currents. Credit: Population of amoeba-like cells separated by volcanic eruption original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Andrea J. Alveshere is a collective work under a <a class=\"rId74\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\">CC BY-NC-SA 4.0 License<\/a>. [Includes <a class=\"rId75\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Amoeba_proteus_TK-UT.svg\">Amoeba Proteus TK-UT<\/a> by <a class=\"rId76\" href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Nefronus\">Tom\u00e1\u0161 Kebert<\/a> and <a class=\"rId77\" href=\"https:\/\/www.umimeto.org\/\">umimeto.org<\/a> (modified), <a class=\"rId78\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/deed.en\">CC BY-SA 4.0<\/a>.]<\/figcaption><\/figure>\n<p class=\"import-Normal\">In the initial generations after the eruption, due to founder effect, isolation, and random inheritance (genetic drift), the population to the west of the islands contained a vast majority of the ruffled membrane alleles while the eastern population carried only the smooth alleles. Ocean currents in the area typically flowed from east to west, sometimes carrying cells (facilitating gene flow) from the eastern (smooth) population to the western (ruffled) population. Due to the ocean currents, it was almost impossible for any cells from the western population to be carried eastward. Thus, for inheritance purposes, the eastern (smooth) population remained isolated. In this case, the gene flow is unidirectional (going only in one direction) and unbalanced (only one population is receiving the new alleles).<\/p>\n<p class=\"import-Normal\">Among humans, gene flow is often described as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1460\"><strong>admixture<\/strong>.<\/a> In forensic cases, anthropologists and geneticists are often asked to estimate the ancestry of unidentified human remains to help determine whether they match any missing persons\u2019 reports. This is one of the most complicated tasks in these professions because, while \u201crace\u201d or \u201cancestry\u201d involves simple checkboxes on a missing person\u2019s form, among humans today there are no truly distinct genetic populations. All modern humans are members of the same fully breeding compatible species, and all human communities have experienced multiple episodes of gene flow (admixture), leading all humans today to be so genetically similar that we are all members of the same (and only surviving) human subspecies: <em>Homo sapiens sapiens.<\/em><\/p>\n<p class=\"import-Normal\">Gene flow between otherwise isolated nonhuman populations is often termed <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1461\">hybridization.<\/a>.<\/strong> One example of this involves the hybridization and spread of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1462\"><strong>Scutellata<\/strong><strong> honey bees<\/strong><\/a> (a.k.a. \u201ckiller bees\u201d) in the Americas. All honey bees worldwide are classified as <em>Apis mellifera.<\/em> Due to distinct adaptations to various environments around the world, there are 28 different subspecies of <em>Apis mellifera<\/em>.<\/p>\n<p class=\"import-Normal\">During the 1950s, a Brazilian biologist named Warwick E. Kerr experimented with hybridizing African and European subspecies of honey bees to try to develop a strain that was better suited to tropical environments than the European honey bees that had long been kept by North American beekeepers. Dr. Kerr was careful to contain the reproductive queens and drones from the African subspecies, but in 1957, a visiting beekeeper accidentally released 26 queen bees of the Scutellata subspecies (<em>Apis mellifera scutellata<\/em>) from southern Africa into the Brazilian countryside. The Scutellata bees quickly interbred with local European honey bee populations. The hybridized bees exhibited a much more aggressively defensive behaviour, fatally or near-fatally attacking many humans and livestock that ventured too close to their hives. The hybridized bees spread throughout South America and reached Mexico and California by 1985. By 1990, permanent colonies had been established in Texas, and by 1997, 90% of trapped bee swarms around Tucson, Arizona, were found to be Scutellata hybrids (Sanford 2006).<\/p>\n<p class=\"import-Normal\">Another example involves the introduction of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1463\"><strong>Harlequin ladybeetle<\/strong><\/a>, <em>Harmonia axyridis<\/em>, native to East Asia, to other parts of the world as a \u201cnatural\u201d form of pest control. Harlequin ladybeetles are natural predators of some of the aphids and other crop-pest insects. First introduced to North America in 1916, the \u201cbiocontrol\u201d strains of Harlequin ladybeetles were considered to be quite successful in reducing crop pests and saving farmers substantial amounts of money. After many decades of successful use in North America, biocontrol strains of Harlequin ladybeetles were also developed in Europe and South America in the 1980s.<\/p>\n<p class=\"import-Normal\">Over the seven decades of biocontrol use, the Harlequin ladybeetle had never shown any potential for development of wild colonies outside of its native habitat in China and Japan. New generations of beetles always had to be reared in the lab. That all changed in 1988, when a wild colony took root near New Orleans, Louisiana. Either through admixture with a native ladybeetle strain, or due to a spontaneous mutation, a new allele was clearly introduced into this population that suddenly enabled them to survive and reproduce in a wide range of environments. This population spread rapidly across the Americas and had reached Africa by 2004.<\/p>\n<p class=\"import-Normal\">In Europe, the invasive, North American strain of Harlequin ladybeetle admixed with the European strain (Figure 5.14), causing a population explosion (Lombaert Et al. 2010). Even strains specifically developed to be flightless (to curtail the spreading) produced flighted offspring after admixture with members of the North American population (Facon Et al. 2011). The fast-spreading, invasive strain has quickly become a disaster, out-competing native ladybeetle populations (some to the point of extinction), causing home infestations, decimating fruit crops, and contaminating many batches of wine with their bitter flavour after being inadvertently harvested with the grapes (Pickering Et al. 2004).<\/p>\n<figure style=\"width: 583px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image13-2.png\" alt=\"One gray ladybug is migrating to the group of white ladybugs.\" width=\"583\" height=\"219\" \/><figcaption class=\"wp-caption-text\">Figure 5.14: Gene flow between two populations of ladybeetles (ladybugs). Credit: <a class=\"rId80\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-3\/\">Ladybug Gene Flow (Figure 4.14)<\/a> original to <a class=\"rId81\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a class=\"rId82\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<h3 class=\"import-Normal\"><strong>Natural Selection<\/strong><\/h3>\n<p class=\"import-Normal\">The final force of evolution is natural selection. This is the evolutionary process that Charles Darwin first brought to light, and it is what the general public typically evokes when considering the process of evolution. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1465\"><strong>Natural <\/strong><strong>s<\/strong><strong>election<\/strong><\/a> occurs when certain phenotypes confer an advantage or disadvantage in survival and\/or reproductive success. The alleles associated with those phenotypes will change in frequency over time due to this selective pressure. It\u2019s also important to note that the advantageous allele may change over time (with environmental changes) and that an allele that had previously been benign may become advantageous or detrimental. Of course, dominant, recessive, and codominant traits will be selected upon a bit differently from one another. Because natural selection acts on phenotypes rather than the alleles themselves, deleterious (disadvantageous) alleles can be retained by heterozygotes without any negative effects.<\/p>\n<p class=\"import-Normal\">In the case of our primordial ocean cells, up until now, the texture of their cell membranes has been benign. The frequencies of smooth to ruffled alleles, and smooth to ruffled phenotypes, has changed over time, due to genetic drift and gene flow. Let\u2019s now imagine that the Earth\u2019s climate has cooled to a point that the waters frequently become too cold for survival of the tiny bacteria that are the dietary staples of our smooth and ruffled cell populations. The way amoeba-like cells \u201ceat\u201d is to stretch out the cell membrane, almost like an arm, to encapsulate, then ingest, the tiny bacteria. When the temperatures plummet, the tiny bacteria populations plummet with them. Larger bacteria, however, are better able to withstand the temperature change.<\/p>\n<p class=\"import-Normal\">The smooth cells were well-adapted to ingesting tiny bacteria but poorly suited to encapsulating the larger bacteria. The cells with the ruffled membranes, however, are easily able to extend their ruffles to encapsulate the larger bacteria. They also find themselves able to stretch their entire membrane to a much larger size than their smooth-surfaced neighbours, allowing them to ingest more bacteria at a given time and to go for longer periods between feedings (Figure 5.15).<\/p>\n<figure style=\"width: 528px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image14-2.png\" alt=\"Smooth and ruffled cells feeding on large and small bacteria.\" width=\"528\" height=\"307\" \/><figcaption class=\"wp-caption-text\">Figure 5.15: Smooth and ruffled cells feeding. Credit: Smooth and ruffled cells feeding original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Andrea J. Alveshere is a collective work under a <a class=\"rId84\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\">CC BY-NC-SA 4.0 License<\/a>. [Includes <a class=\"rId85\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Cladograma_dos_Dom%C3%ADnios_e_Reinos.png\">Cladograma dos Dominios e Reinos<\/a> by <a class=\"rId86\" href=\"https:\/\/commons.wikimedia.org\/wiki\/User:MarceloTeles\">MarceloTeles<\/a> (modified), <a class=\"rId87\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/deed.en\">CC BY-SA 4.0<\/a><a class=\"rId88\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/deed.en\">; <\/a><a class=\"rId89\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Amoeba_proteus_TK-UT.svg\">Amoeba Proteus TK-UT<\/a> by <a class=\"rId90\" href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Nefronus\">Tom\u00e1\u0161 Kebert<\/a> and <a class=\"rId91\" href=\"https:\/\/www.umimeto.org\/\">umimeto.org<\/a> (modified), <a class=\"rId92\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/deed.en\">CC BY-SA 4.0<\/a>.]<\/figcaption><\/figure>\n<p class=\"import-Normal\">The smooth and ruffled traits, which had previously offered no advantage or disadvantage while food was plentiful, now are subject to natural selection. During the cold snaps, at least, the ruffled cells have a definite advantage. We can imagine that the western population that has mostly ruffled alleles will continue to do well, while the eastern population is at risk of dying out if the smaller bacteria remain scarce and no ruffled alleles are introduced.<\/p>\n<p class=\"import-Normal\">A classic example of natural selection involves the study of an insect called the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1466\">peppered moth<\/a><\/strong> (<em>Biston betularia<\/em>) in England during the Industrial Revolution in the 1800s. Prior to the Industrial Revolution, the peppered moth population was predominantly light in colour, with dark (pepper-like) speckles on the wings. The \u201cpeppered\u201d colouration was very similar to the appearance of the bark and lichens that grew on the local trees (Figure 5.16). This helped to camouflage the moths as they rested on a tree, making it harder for moth-eating birds to find and snack on them. There was another phenotype that popped up occasionally in the population. These individuals were heterozygotes that carried an overactive, dominant pigment allele, producing a solid black colouration. As you can imagine, the black moths were much easier for birds to spot, making this phenotype a real disadvantage.<\/p>\n<p class=\"import-Normal\">The situation changed, however, as the Industrial Revolution took off. Large factories began spewing vast amounts of coal smoke into the air, blanketing the countryside, including the lichens and trees, in black soot. Suddenly, it was the light-coloured moths that were easy for birds to spot and the black moths that held the advantage. The frequency of the dark pigment allele rose dramatically. By 1895, the black moth phenotype accounted for 98% of observed moths (Grant 1999).<\/p>\n<figure style=\"width: 476px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image15-2.png\" alt=\"An illustration of natural selection.\" width=\"476\" height=\"531\" \/><figcaption class=\"wp-caption-text\">Figure 5.16: Dark and light peppered moth variants and their relative camouflage abilities on clean (top) and sooty (bottom) trees. Credit: <a class=\"rId94\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Peppered_moths_c2.jpg\">Peppered moths c2<\/a> by Khaydock is under a <a class=\"rId95\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Thanks to new environmental regulations in the 1960s, the air pollution in England began to taper off. As the soot levels decreased, returning the trees to their former, lighter colour, this provided the perfect opportunity to study how the peppered moth population would respond. Repeated follow-up studies documented the gradual rise in the frequency of the lighter-coloured phenotype. By 2003, the maximum frequency of the dark phenotype was 50% and in most parts of England had decreased to less than 10% (Cook, 2003).<\/p>\n<h4 class=\"import-Normal\"><em>Directional, Balancing\/Stabilizing, and Disruptive\/Diversifying Selection<\/em><\/h4>\n<p class=\"import-Normal\">Natural selection can be classified as directional, balancing\/stabilizing, or disruptive\/diversifying, depending on how the pressure is applied to the population (Figure 5.17).<\/p>\n<figure style=\"width: 465px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image16-2.png\" alt=\"Three types of selection; balancing, directional and disruptive\/diversifying\" width=\"465\" height=\"574\" \/><figcaption class=\"wp-caption-text\">Figure 5.17: Lines depict the affects of (a) Balancing\/Stabilizing, (b) Directional, and (c) Disruptive\/Diversifying selection on populations. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\" rel=\"noopener\">A full text description of this image is available<\/a>. Credit: <a class=\"rId97\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Figure_19_03_01.png\">Biology (ID: 185cbf87-c72e-48f5-b51e-f14f21b5eabd@9.17)<\/a> by <a class=\"rId98\" href=\"https:\/\/cnx.org\/\">CNX OpenStax<\/a> is used under a <a class=\"rId99\" href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/deed.en\">CC BY 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Both of the above examples of natural selection involve <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1467\">directional selection<\/a><\/strong>: the environmental pressures favour one phenotype over the other and cause the frequencies of the associated advantageous alleles (ruffled membranes, dark pigment) to gradually increase. In the case of the peppered moths, the direction shifted three times: first, it was selecting for lighter pigment; then, with the increase in pollution, the pressure switched to selection for darker pigment; finally, with reduction of the pollution, the selection pressure shifted back again to favouring light-coloured moths.<\/p>\n<p class=\"import-Normal\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1468\"><strong>Balancing selection<\/strong><\/a> (a.k.a. stabilizing selection) occurs when selection works against the extremes of a trait and favours the intermediate phenotype. For example, humans maintain an average birth weight that balances the need for babies to be small enough not to cause complications during pregnancy and childbirth but big enough to maintain a safe body temperature after they are born. Another example of balancing selection is found in the genetic disorder called sickle cell anemia (see \u201cSpecial Topic: Sickle Cell Anemia\u201d).<\/p>\n<p class=\"import-Normal\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1469\"><strong>Disruptive selection<\/strong><\/a> (a.k.a. diversifying selection), the opposite of balancing selection, occurs when both extremes of a trait are advantageous. Since individuals with traits in the mid-range are selected against, disruptive selection can eventually lead to the population evolving into two separate species. Darwin believed that the many species of finches (small birds) found in the remote Galapagos Islands provided a clear example of disruptive selection leading to speciation. He observed that seed-eating finches either had large beaks, capable of eating very large seeds, or small beaks, capable of retrieving tiny seeds. The islands did not have many plants that produced medium-size seeds. Thus, birds with medium-size beaks would have trouble eating the very large seeds and would also have been inefficient at picking up the tiny seeds. Over time, Darwin surmised, this pressure against mid-size beaks may have led the population to divide into two separate species.<\/p>\n<h4 class=\"import-Normal\"><em>Sexual Selection<\/em><\/h4>\n<p class=\"import-Normal\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1470\"><strong>Sexual <\/strong><strong>s<\/strong><strong>election<\/strong><\/a> is an aspect of natural selection in which the selective pressure specifically affects reproductive success (the ability to successfully breed and raise offspring) rather than survival. Sexual selection favours traits that will attract a mate. Sometimes these sexually appealing traits even carry greater risks in terms of survival.<\/p>\n<figure style=\"width: 354px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image17-2.png\" alt=\"A fox chases a peacock fleeing; a peacock displays his feathers to a peahen.\" width=\"354\" height=\"413\" \/><figcaption class=\"wp-caption-text\">Figure 5.18: Showy peacock tail disadvantages (becoming easier prey) and advantages (impressing peahens). Credit: <a class=\"rId101\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-3\/\">Peacock tail advantage and disadvantages (Figure 4.18)<\/a> original to <a class=\"rId102\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a class=\"rId103\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.License.<\/figcaption><\/figure>\n<p class=\"import-Normal\">A classic example of sexual selection involves the brightly coloured feathers of the peacock. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1471\"><strong>peacock<\/strong><\/a> is the male sex of the peafowl genera <em>Pavo<\/em> and <em>Afropavo. <\/em>During mating season, peacocks will fan their colourful tails wide and strut in front of the peahens in a grand display. The peahens will carefully observe these displays and will elect to mate with the male that they find the most appealing. Many studies have found that peahens prefer the males with the fullest, most colourful tails. While these large, showy tails provide a reproductive advantage, they can be a real burden in terms of escaping predators. The bright colours and patterns as well as the large size of the peacock tail make it difficult to hide. Once predators spot them, peacocks also struggle to fly away, with the heavy tail trailing behind and weighing them down (Figure 5.18). Some researchers have argued that the increased risk is part of the appeal for the peahens: only an especially strong, alert, and healthy peacock would be able to avoid predators while sporting such a spectacular tail.<\/p>\n<p>&lt;!-- <\/p><\/div>\n<p> --&gt;<br \/>\nIt\u2019s important to keep in mind that sexual selection relies on the trait being present throughout mating years. Reflecting on the NF1 genetic disorder (see \u201cSpecial Topic: Neurofibromatosis Type 1 [NF1]\u201d), given how disfiguring the symptoms can become, some might find it surprising that half of the babies born with NF1 inherited it from a parent. Given that the disorder is autosomal dominant and fully penetrant (meaning it has no unaffected carriers), it may seem surprising that sexual selection doesn\u2019t exert more pressure against the mutated alleles. One important factor is that, while the neurofibromas typically begin to appear during puberty, they usually emerge only a few at a time and may grow very slowly. Many NF1 patients don\u2019t experience the more severe or disfiguring symptoms until later in life, long after they have started families of their own.<\/p>\n<p class=\"import-Normal\">Some researchers prefer to classify sexual selection separately, as a fifth force of evolution. The traits that underpin mate selection are entirely natural, of course. Research has shown that subtle traits, such as the type of pheromones (hormonal odors related to immune system alleles) someone emits and how those are perceived by the immune system genotype of the \u201csniffer,\u201d may play crucial and subconscious roles in whether we find someone attractive or not (Chaix, Cao, &amp; Donnelly 2008).<\/p>\n<div class=\"textbox\">\n<h2><\/h2>\n<h2 class=\"import-Normal\">Special Topic: Neurofibromatosis Type 1 (NF1)<\/h2>\n<p class=\"import-Normal\"><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1476\">Neurofibromatosis Type 1<\/a><\/strong>, also known as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1477\"><strong>NF1<\/strong><\/a>, is a genetic disorder that illustrates how a mutation in a single gene can affect multiple systems in the body. Surprisingly common, more people have NF1 than cystic fibrosis and muscular dystrophy combined. Even more surprising, given how common it is, is how few people have heard of it. One in every 3,000 babies is born with NF1, and this holds true for all populations worldwide (Riccardi 1992). This means that, for every 3,000 people in your community, there is likely at least one person living with this disorder. NF1 is an <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1478\">autosomal dominant<\/a> <\/strong>condition, which means that everyone born with a mutation in the gene, whether inherited or spontaneous, has a 50\/50 chance of passing it on to each of their own children.<\/p>\n<p class=\"import-Normal\">The NF1 disorder results from mutation of the <em>NF1<\/em> gene on Chromosome 17. Almost any mutation that affects the sequence of the gene\u2019s protein product, neurofibromin, will cause the disorder. Studies of individuals with NF1 have identified over 3,000 different mutations of all kinds (including point mutations, small and large indels, and translocations). The <em>NF1 <\/em>gene is one of the largest known genes, containing at least 60 <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_724\">exons<\/a><\/strong> (protein-encoding sequences) in a span of about 300,000 nucleotides.<\/p>\n<p class=\"import-Normal\">We know that neurofibromin plays an important role in preventing tumor growth because one of the most common symptoms of the NF1 disorder is the growth of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1479\">benign<\/a> <\/strong>(noncancerous) tumors, called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1486\">neurofibromas<\/a><\/strong>. Neurofibromas sprout from nerve sheaths\u2014the tissues that encase our nerves\u2014throughout the body, usually beginning around puberty. There is no way to predict where the tumors will occur, or when or how quickly they will grow, although only about 15% turn <strong>malignant<\/strong> (cancerous). The two types of neurofibromas that are typically most visible are <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1480\"><strong>cutaneous neurofibromas<\/strong><\/a>, which are spherical bumps on, or just under, the surface of the skin (Figure 5.19), and <strong>plexiform neurofibromas<\/strong><em>, <\/em>growths involving whole branches of nerves, often giving the appearance that the surface of the skin is \u201cmelting\u201d (Figure 5.20).<\/p>\n<figure id=\"attachment_131-5\" aria-describedby=\"caption-attachment-131-5\" style=\"width: 510px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-129\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/4.18.jpg\" alt=\"A woman has dozens of round, skin-colored tumors visible on her face, neck, and hand.\" width=\"510\" height=\"340\" \/><figcaption id=\"caption-attachment-131-5\" class=\"wp-caption-text\">Figure 5.19: A woman with many cutaneous neurofibromas, a common symptom of Neurofibromatosis Type 1. Credit: <a class=\"rId105\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-3\/\">Woman with cutaneous neurofibromas (symptom of NF1)<\/a> by <a class=\"rId106\" href=\"https:\/\/positiveexposure.org\/about-the-program-2\/rick-guidotti\/\">Rick Guidotti of Positive Exposure<\/a> is used with permission and is available here under a <a class=\"rId107\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<figure id=\"attachment_131-6\" aria-describedby=\"caption-attachment-131-6\" style=\"width: 1900px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-130 size-full\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/4.19.jpg\" alt=\"An adult with large plexiform neurofibromas covering his face, none are on the child.\" width=\"1900\" height=\"700\" \/><figcaption id=\"caption-attachment-131-6\" class=\"wp-caption-text\">Figure 5.20: Photo on the left is of a man with large plexiform neurofibroma, another symptom of Neurofibromatosis Type 1. Photo on the right is a childhood photo of the same man, illustrating the progressive nature of the NF1 disorder. Credit: <a class=\"rId110\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-3\/\">Man with plexiform neurofibroma (symptom of NF1)<\/a> from Ashok Shrestha is used by permission and available here under a <a class=\"rId111\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>. <a class=\"rId112\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-3\/\">Childhood photo of the same man with NF1 disorder<\/a> from Ashok Shrestha is used by permission and available here under a <a class=\"rId113\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Unfortunately, there is currently no cure for NF1. Surgical removal of neurofibromas risks paralysis, due to the high potential for nerve damage, and often results in the tumors growing back even more vigorously. This means that patients are often forced to live with disfiguring and often painful neurofibromas. People who are not familiar with NF1 often mistake neurofibromas for something contagious. This makes it especially hard for people living with NF1 to get jobs working with the public or even to enjoy spending time away from home. Raising public awareness about NF1 and its symptoms can be a great help in improving the quality of life for people living with this condition.<\/p>\n<figure style=\"width: 311px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image21-2.png\" alt=\"A child with darker oval birthmarks scattered across his torso and arms.\" width=\"311\" height=\"415\" \/><figcaption class=\"wp-caption-text\">Figure 5.21: Image of a child with caf\u00e9-au-lait macules (birthmarks) typical of the earliest symptoms of NF1. Credit: <a class=\"rId115\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-3\/\">Child with caf\u00e9-au-lait macules (birthmarks) typical of the earliest symptoms of NF1<\/a> by Andrea J. Alveshere is under a <a class=\"rId116\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">One of the first symptoms of NF1 in a small child is usually the appearance of <strong>caf\u00e9-au-lait spots<\/strong>, or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1490\"><strong>CALS<\/strong><\/a>, which are flat, brown birthmark-like spots on the skin (Figure 5.21). CALS are often light brown, similar to the colour of coffee with cream, which is the reason for the name, although the shade of the pigment depends on a person\u2019s overall complexion. Some babies are born with CALS, but for others the spots appear within the first few years of life. Having six or more CALS larger than five millimetres (mm) across is a strong indicator that a child may have NF1.<\/p>\n<p class=\"import-Normal\">Other common symptoms include the following: gliomas (tumors) of the optic nerve, which can cause vision loss; thinning of bones and failure to heal if they break (often requiring amputation); low muscle tone (poor muscle development, often delaying milestones such as sitting up, crawling, and walking); hearing loss, due to neurofibromas on auditory nerves; and learning disabilities, especially those involving spatial reasoning. Approximately 50% of people with NF1 have some type of speech and\/or learning disability and often benefit greatly from early intervention services. Generalized developmental disability, however, is not common with NF1, so most people with NF1 live independently as adults. Many people with NF1 live full and successful lives, as long as their symptoms can be managed.<\/p>\n<p class=\"import-Normal\">Based on the wide variety of symptoms, it\u2019s clear that the neurofibromin protein plays important roles in many biochemical pathways. While everyone who has NF1 will exhibit some symptoms during their lifetime, there is a great deal of variation in the types and severity of symptoms, even between individuals from the same family who share the exact same NF1 mutation. It seems crazy that a gene with so many important functions would be so susceptible to mutation. Part of this undoubtedly has to do with its massive size\u2014a gene with 300,000 nucleotides has ten times more nucleotides available for mutation than does a gene of 30,000 bases. This also suggests that the mutability of this gene might provide some benefits, which is a possibility that we will revisit later in this chapter.<\/p>\n<\/div>\n<div class=\"textbox\">\n<h2 class=\"import-Normal\">Special Topic: Sickle Cell Anemia<\/h2>\n<p class=\"import-Normal\"><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1492\">Sickle cell anemia<\/a><\/strong> is an autosomal recessive genetic disorder that affects millions of people worldwide. It is most common in Africa, countries around the Mediterranean Sea, and eastward as far as India. Populations in the Americas that have high percentages of ancestors from these regions also have high rates of sickle cell anemia. In the United States, it\u2019s estimated that 72,000 people live with the disease, with one in approximately 1,200 Hispanic-American babies and one in every 500 African-American babies inheriting the condition (World Health Organization 1996).<\/p>\n<figure style=\"width: 344px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image22-2.png\" alt=\"Round and sickle cells.\" width=\"344\" height=\"258\" \/><figcaption class=\"wp-caption-text\">Figure 5.22: Sickle cell anemia. Arrows indicate (a) sickled and (b) normal red blood cells. Credit: <a class=\"rId118\" href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Sickle-cell_smear_2015-09-10.jpg\">Sickle-cell smear 2015-09-10<\/a> by Paulo Henrique Orlandi Mourao has been modified (contrast modified and labels added) and is under a <a class=\"rId119\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\">CC BY-NC-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Sickle cell anemia affects the hemoglobin protein in red blood cells. Normal red blood cells are somewhat doughnut-shaped\u2014round with a depression on both sides of the middle. They carry oxygen around the bloodstream to cells throughout the body. Red blood cells produced by the mutated form of the gene take on a stiff, sickle-like crescent shape when stressed by low oxygen or dehydration (Figure 5.22). Because of their elongated shape and the fact that they are stiff rather than flexible, they tend to form clumps in the blood vessels, inhibiting blood flow to adjacent areas of the body. This causes episodes of extreme pain and can cause serious problems in the oxygen-deprived tissues. The sickle cells also break down much more quickly than normal cells, often lasting only 20 days rather than the 120 days of normal cells. This causes an overall shortage of blood cells in the sickle cell patient, resulting in low iron (anemia) and problems associated with it such as extreme fatigue, shortness of breath, and hindrances to children\u2019s growth and development.<\/p>\n<p class=\"import-Normal\">The devastating effects of sickle cell anemia made its high frequency a pressing mystery. Why would an allele that is so deleterious in its homozygous form be maintained in a population at levels as high as the one in twelve African Americans estimated to carry at least one copy of the allele? The answer turned out to be one of the most interesting cases of balancing selection in the history of genetic study.<\/p>\n<p class=\"import-Normal\">While looking for an explanation, scientists noticed that the countries with high rates of sickle cell disease also shared a high risk for another disease called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1493\"><strong>malaria<\/strong><\/a>, which is caused by infection of the blood by a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1494\"><strong><em>Plasmodium<\/em><\/strong><\/a> parasite. These parasites are carried by mosquitoes and enter the human bloodstream via a mosquito bite. Once infected, the person will experience flu-like symptoms that, if untreated, can often lead to death. Researchers discovered that many people living in these regions seemed to have a natural resistance to malaria. Further study revealed that people who carry the sickle cell allele are far less likely to experience a severe case of malaria. This would not be enough of a benefit to make the allele advantageous for the sickle cell homozygotes, who face shortened life spans due to sickle cell anemia. The real benefit of the sickle cell allele goes to the heterozygotes.<\/p>\n<p class=\"import-Normal\">People who are heterozygous for sickle cell carry one normal allele, which produces the normal, round, red blood cells, and one sickle cell allele, which produces the sickle-shaped red blood cells. Thus, they have both the sickle and round blood cell types in their bloodstream. They produce enough of the round red blood cells to avoid the symptoms of sickle cell anemia, but they have enough sickle cells to provide protection from malaria.<\/p>\n<p class=\"import-Normal\">When the <em>Plasmodium <\/em>parasites infect an individual, they begin to multiply in the liver, but then must infect the red blood cells to complete their reproductive cycle. When the parasites enter sickle-type cells, the cells respond by taking on the sickle shape. This prevents the parasite from circulating through the bloodstream and completing its life cycle, greatly inhibiting the severity of the infection in the sickle cell heterozygotes compared to non\u2013-sickle cell homozygotes. See Chapter 14 for more discussion of sickle cell anemia.<\/p>\n<\/div>\n<div class=\"textbox\">\n<h2 class=\"import-Normal\">Special Topic: The Real Primordial Cells\u2014<em>Dictyostelium Discoideum<\/em><\/h2>\n<p class=\"import-Normal\">The amoeba-like primordial cells that were used as recurring examples throughout this chapter are inspired by actual research that is truly fascinating. In 2015, Gareth Bloomfield and colleagues reported on their genomic study of the social amoeba <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1496\"><strong><em>Dictyostelium discoideum<\/em><\/strong> <\/a>(a.k.a. \u201cslime molds,\u201d although technically they are amoebae, not molds). Strains of these amoebae have been grown in research laboratories for many decades and are useful in studying the mechanisms that amoeboid single-celled organisms use to ingest food and liquid. For simplification of our examples in this chapter, our amoeba-like cells remained ocean dwellers. Wild <em>Dictyostelium discoideum<\/em>, however, live in soil and feed on soil bacteria by growing ruffles in their membranes that reach out to encapsulate the bacterial cell. Laboratory strains, however, are typically raised on liquid media (agar) in Petri dishes, which is not suitable for the wild-type amoebae. It was widely known that the laboratory strains must have developed mutations in one or more genes to allow them to ingest the larger nutrient particles in the agar and larger volumes of liquid, but the genes involved were not known.<\/p>\n<p class=\"import-Normal\">Bloomfield and colleagues performed genomic testing on both the wild and the laboratory strains of <em>Dictyostelium discoideum. <\/em>Their discovery was astounding: every one of the laboratory strains carried a mutation in the <em>NF1 <\/em>gene, the very same gene associated with Neurofibromatosis Type 1 (NF1) in humans. The antiquity of this massive, easily mutated gene is incredible. It originated in an ancestor common to both humans and these amoebae, and it has been retained in both lineages ever since. As seen in <em>Dictyostelium discoideum<\/em>, breaking the gene can be advantageous. Without a functioning copy of the neurofibromin protein, the cell membrane is able to form much-larger feeding structures, allowing the <em>NF1 <\/em>mutants to ingest larger particles and larger volumes of liquid. For these amoebae, this may provide dietary flexibility that functions somewhat like an insurance policy for times when the food supply is limited.<\/p>\n<p class=\"import-Normal\"><em>Dictyostelium discoideum <\/em>are also interesting in that they typically reproduce asexually, but under certain conditions, one cell will convert into a \u201cgiant\u201d cell, which encapsulates surrounding cells, transforming into one of three sexes. This cell will undergo meiosis, producing gametes that must combine with one of the other two sexes to produce viable offspring. This ability for sexual reproduction may be what allows <em>Dictyostelium discoideum<\/em> to benefit from the advantages of <em>NF1<\/em> mutation, while also being able to restore the wild type <em>NF1<\/em> gene in future generations.<\/p>\n<p class=\"import-Normal\">What does this mean for humans living with NF1? Well, understanding the role of the neurofibromin protein in the membranes of simple organisms like <em>Dictyostelium discoideum<\/em> may help us to better understand how it functions and malfunctions in the sheaths of human neurons. It\u2019s also possible that the mutability of the NF1 gene confers certain advantages to humans as well. Alleles of the NF1 gene have been found to reduce one\u2019s risk for alcoholism (Repunte-Canonigo Vez Et al. 2015), opiate addiction (Sanna Et al. 2002), Type 2 diabetes (Martins Et al. 2016), and hypomusicality (a lower-than-average musical aptitude; Cota Et al. 2018). This research is ongoing and will be exciting to follow in the coming years.<\/p>\n<\/div>\n<h2 class=\"__UNKNOWN__\">Studying Evolution in Action<\/h2>\n<div class=\"__UNKNOWN__\">\n<h3 class=\"import-Normal\"><strong>The Hardy-Weinberg Equilibrium <\/strong><\/h3>\n<p class=\"import-Normal\">This chapter has introduced you to the forces of evolution, the mechanisms by which evolution occurs. How do we detect and study evolution, though, in real time, as it happens? One tool we use is the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1497\"><strong>Hardy-<\/strong><strong>Weinberg<\/strong><strong> Equilibrium<\/strong><\/a>: a mathematical formula that allows estimation of the number and distribution of dominant and recessive alleles in a population. This aids in determining whether allele frequencies are changing and, if so, how quickly over time, and in favour of which allele? It\u2019s important to note that the Hardy-Weinberg formula only gives us an estimate based on the data for a snapshot in time. We will have to calculate it again later, after various intervals, to determine if our population is evolving and in what way the allele frequencies are changing.<\/p>\n<h3 class=\"import-Normal\">Calculating the Hardy-Weinberg Equilibrium<\/h3>\n<p class=\"import-Normal\">In the Hardy-Weinberg formula, <em>p <\/em>represents the frequency of the dominant allele, and <em>q<\/em> represents the frequency of the recessive allele. Remember, an allele\u2019s frequency is the proportion, or percentage, of that allele in the population. For the purposes of Hardy-Weinberg, we give the allele percentages as decimal numbers (e.g., 42% = 0.42), with the entire population (100% of alleles) equaling 1. If we can figure out the frequency of one of the alleles in the population, then it is simple to calculate the other. Simply subtract the known frequency from 1 (the entire population): 1<em> \u2013 p = q<\/em> and 1<em> \u2013 q = p<\/em>.<\/p>\n<p class=\"import-Normal\">The Hardy-Weinberg formula is <em>p<\/em><sup><em>2<\/em><\/sup><em> + 2pq + q<\/em><sup><em>2<\/em><\/sup>, where:<\/p>\n<p class=\"import-Normal\" style=\"padding-left: 40px\"><em>p<\/em><sup><em>2<\/em><\/sup> represents the frequency of the homozygous dominant genotype;<\/p>\n<p class=\"import-Normal\" style=\"padding-left: 40px\"><em>2pq<\/em> represents the frequency of the heterozygous genotype; and<\/p>\n<p class=\"import-Normal\" style=\"padding-left: 40px\"><em>q<\/em><sup><em>2<\/em><\/sup> represents the frequency of the homozygous recessive genotype.<\/p>\n<p class=\"import-Normal\">It is often easiest to determine <em>q<\/em><sup><em>2<\/em><\/sup> first, simply by counting the number of individuals with the unique, homozygous recessive phenotype (then dividing by the total individuals in the population to arrive at the \u201cfrequency\u201d). Once we have this number, we simply need to calculate the square root of the homozygous recessive phenotype frequency. That gives us <em>q.<\/em> Remember, 1 <em>\u2013<\/em> <em>q <\/em>equals <em>p<\/em>, so now we have the frequencies for both alleles in the population. If we needed to figure out the frequencies of heterozygotes and homozygous dominant genotypes, we\u2019d just need to plug the <em>p<\/em> and <em>q<\/em> frequencies back into the <em>p<\/em><sup><em>2<\/em><\/sup> and 2<em>pq<\/em> formulas.<\/p>\n<figure style=\"width: 329px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image25-1.png\" alt=\"A circle with seven grey and three white ladybugs.\" width=\"329\" height=\"347\" \/><figcaption class=\"wp-caption-text\">Figure 5.23: Ladybug population with a mixture of dark (red) and light (orange) individuals. Credit: <a class=\"rId129\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-3\/\">Ladybug mix (Figure 4.21)<\/a> original to <a class=\"rId130\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a class=\"rId131\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Let\u2019s imagine we have a population of ladybeetles that carries two alleles: a dominant allele that produces red ladybeetles and a recessive allele that produces orange ladybeetles. Since red is dominant, we\u2019ll use <em>R <\/em>to represent the red allele, and <em>r <\/em>to represent the orange allele. Our population has ten beetles, and seven are red and three are orange (Figure 5.23). Let\u2019s calculate the number of genotypes and alleles in this population.<\/p>\n<p class=\"import-Normal\">Of ten total beetles, we have three orange beetles3\/10 = .30 (30%) frequency\u2014and we know they are homozygous recessive (<em>rr<\/em>). So:<\/p>\n<p class=\"import-Normal\" style=\"text-indent: 36pt\"><em>rr = .3; <\/em>therefore, <em>r = <\/em>\u221a.3 = .5477<\/p>\n<p class=\"import-Normal\" style=\"text-indent: 36pt\"><em>R<\/em> = 1 <em>\u2013<\/em> .5477 = .4523<\/p>\n<p class=\"import-Normal\" style=\"text-indent: 36pt\">Using the Hardy-Weinberg formula:<\/p>\n<p class=\"import-Normal\" style=\"text-indent: 36pt\">1=.4523<sup>2 <\/sup>+ 2 x .4523 x .5477 +.5477<sup>2 <\/sup>= .20 + .50 + .30 = 1<\/p>\n<p class=\"import-Normal\" style=\"text-indent: 36pt\">Thus, the genotype breakdown is 20% <em>RR, <\/em>50%<em> Rr, <\/em>and 30%<em> rr <\/em><\/p>\n<p class=\"import-Normal\" style=\"text-indent: 36pt\">(2 red homozygotes, 5 red heterozygotes, and 3 orange homozygotes).<\/p>\n<p class=\"import-Normal\">Since we have 10 individuals, we know we have 20 total alleles: 4 red from the <em>RR<\/em> group, 5 red and 5 orange from the <em>Rr<\/em> group, and 6 orange from the <em>rr<\/em> group, for a grand total of 9 red and 11 orange (45% red and 55% orange, just like we estimated in the 1 \u2013 <em>q <\/em>step).<\/p>\n<p class=\"import-Normal\">Reminder: The Hardy-Weinberg formula only gives us an estimate for a snapshot in time. We will have to calculate it again later, after various intervals, to determine if our population is evolving and in what way the allele frequencies are changing.<\/p>\n<h3 class=\"import-Normal\"><strong>Interpreting Evolutionary Change: Nonra<\/strong><strong>ndom Mating <\/strong><\/h3>\n<p class=\"import-Normal\">Once we have detected change occurring in a population, we need to consider which evolutionary processes might be the cause of the change. It is important to watch for nonrandom mating patterns, to see if they can be included or excluded as possible sources of variation in allele frequencies.<\/p>\n<p class=\"import-Normal\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1498\"><strong>Nonrandom <\/strong><strong>m<\/strong><strong>ating<\/strong><\/a> (also known as assortative mating) occurs when mate choice within a population follows a nonrandom pattern.<\/p>\n<p class=\"import-Normal\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1499\"><strong>Positive assortative mating<\/strong><\/a> patterns result from a tendency for individuals to mate with others who share similar phenotypes. This often happens based on body size. Taking as an example dog breeds, it is easier for two Chihuahuas to mate and have healthy offspring than it is for a Chihuahua and a St. Bernard to do so. This is especially true if the Chihuahua is the female and would have to give birth to giant St. Bernard pups.<\/p>\n<p class=\"import-Normal\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1500\"><strong>Negative assortative mating<\/strong><\/a> patterns occur when individuals tend to select mates with qualities different from their own. This is what is at work when humans choose partners whose pheromones indicate that they have different and complementary immune alleles, providing potential offspring with a better chance at a stronger immune system.<\/p>\n<p class=\"import-Normal\">Among domestic animals, such as pets and livestock, assortative mating is often directed by humans who decide which pairs will mate to increase the chances of offspring having certain desirable traits. This is known as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1501\"><strong>a<\/strong><strong>rtificial <\/strong><strong>s<\/strong><strong>election<\/strong><em>.<\/em><\/a><\/p>\n<p class=\"import-Normal\">Among humans, in addition to phenotypic traits, cultural traits such as religion and ethnicity may also influence assortative mating patterns.<\/p>\n<h3 class=\"import-Normal\"><strong>Defining a Species<\/strong><\/h3>\n<p class=\"import-Normal\"><em>Species<\/em> are organisms whose individuals are capable of breeding because they are biologically and behaviourally compatible to produce viable, fertile offspring. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1502\"><strong>Viable offspring<\/strong><\/a> are those offspring that are healthy enough to survive to adulthood. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1503\"><strong>Fertile offspring<\/strong><\/a> are able to reproduce successfully, resulting in offspring of their own. Both conditions must be met for individuals to be considered part of the same species. As you can imagine, these criteria complicate the identification of distinct species in fossilized remains of extinct populations. In those cases, we must examine how much phenotypic variation is typically found within a comparable modern-day species; we can then determine whether the fossilized remains fall within the expected range of variation for a single species.<\/p>\n<p class=\"import-Normal\">Some species have subpopulations that are regionally distinct. These are classified as separate <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1505\">subspecies<\/a><\/strong> because they have their own unique phenotypes and are geographically isolated from one another. However, if they do happen to encounter one another, they are still capable of successful interbreeding.<\/p>\n<p class=\"import-Normal\">There are many examples of sterile hybrids that are offspring of parents from two different species. For example, horses and donkeys can breed and have offspring together. Depending on which species is the mother and which is the father, the offspring are either called mules, or hennies. Mules and hennies can live full life spans but are not able to have offspring of their own. Likewise, tigers and lions have been known to mate and have viable offspring. Again, depending on which species is the mother and which is the father, these offspring are called either ligers or tigons. Like mules and hennies, ligers and tigons are unable to reproduce. In each of these cases, the mismatched set of chromosomes that the offspring inherit produce an adequate set of functioning genes for the hybrid offspring; however, once mixed and divided in meiosis, the gametes don\u2019t contain the full complement of genes needed for survival in the third generation.<\/p>\n<h3 class=\"import-Normal\"><strong>Micro- to Macroevolution<\/strong><\/h3>\n<p class=\"import-Normal\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1506\"><strong>Microevolution<\/strong><\/a> refers to changes in allele frequencies within breeding populations\u2014that is, within single species. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1507\"><strong>Macroevolution<\/strong><\/a> describes how the similarities and differences between species, as well as the phylogenetic relationships with other taxa, lead to changes that result in the emergence of new species. Consider our example of the peppered moth that illustrated microevolution over time, via directional selection favouring the peppered allele when the trees were clean and the dark pigment allele when the trees were sooty. Imagine that environmental regulations had cleaned up the air pollution in one part of the nation, while the coal-fired factories continued to spew soot in another area. If this went on long enough, it\u2019s possible that two distinct moth populations would eventually emerge\u2014one containing only the peppered allele and the other only harbouring the dark pigment allele.<\/p>\n<p class=\"import-Normal\">When a single population divides into two or more separate species, it is called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1508\"><strong>speciation<\/strong><\/a>. The changes that prevent successful breeding between individuals who descended from the same ancestral population may involve chromosomal rearrangements, changes in the ability of the sperm from one species to permeate the egg membrane of the other species, or dramatic changes in hormonal schedules or mating behaviours that prevent members from the new species from being able to effectively pair up.<\/p>\n<p class=\"import-Normal\">There are two types of speciation: allopatric and sympatric. <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1509\">Allopatric speciation<\/a><\/strong> is caused by long-term <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1510\"><strong>isolation<\/strong><\/a> (physical separation) of subgroups of the population (Figure 5.24). Something occurs in the environment\u2014perhaps a river changes its course and splits the group, preventing them from breeding with members on the opposite riverbank. Over many generations, new mutations and adaptations to the different environments on each side of the river may drive the two subpopulations to change so much that they can no longer produce fertile, viable offspring, even if the barrier is someday removed.<\/p>\n<figure style=\"width: 1000px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image23-2.png\" alt=\"Process of isolation leading to speciation, as described in the figure caption.\" width=\"1000\" height=\"379\" \/><figcaption class=\"wp-caption-text\">Figure 5.24: Isolation leading to speciation: a. original population before isolation; b. a barrier divides the population and prevents interbreeding between the two groups; c. time passes, and the populations become genetically distinct; d. after many generations, the two populations are no longer biologically or behaviourally compatible, thus can no longer interbreed, even if the barrier is removed. Credit: <a class=\"rId121\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-3\/\">Isolation Leading to Speciation (Figure 4.19)<\/a> original to <a class=\"rId122\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a class=\"rId123\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\"><strong>Sympatric speciation<\/strong> occurs when the population splits into two or more separate species while remaining located together <em>without<\/em> a physical barrier. This typically results from a new mutation that pops up among some members of the population that prevents them from successfully reproducing with anyone who does not carry the same mutation. This is seen particularly often in plants, as they have a higher frequency of chromosomal duplications.<\/p>\n<p class=\"import-Normal\">One of the quickest rates of speciation is observed in the case of adaptive radiation. <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1512\">Adaptive radiation<\/a><\/strong> refers to the situation in which subgroups of a single species rapidly diversify and adapt to fill a variety of ecological niches. An <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1513\"><strong>e<\/strong><strong>cological niche<\/strong><\/a> is a set of constraints and resources that is available in an environmental setting. Evidence for adaptive radiations is often seen after population bottlenecks. A mass disaster kills off many species, and the survivors have access to a new set of territories and resources that were either unavailable or much coveted and fought over before the disaster. The offspring of the surviving population will often split into multiple species, each of which stems from members in that first group of survivors who happened to carry alleles that were advantageous for a particular niche.<\/p>\n<p class=\"import-Normal\">The classic example of adaptive radiation brings us back to Charles Darwin and his observations of the many species of finches on the Galapagos Islands. We are still not sure how the ancestral population of finches first arrived on that remote Pacific Island chain, but they found themselves in an environment filled with various insects, large and tiny seeds, fruit, and delicious varieties of cactus. Some members of that initial population carried alleles that gave them advantages for each of these dietary niches. In subsequent generations, others developed new mutations, some of which were beneficial. These traits were selected for, making the advantageous alleles more common among their offspring. As the finches spread from one island to the next, they would be far more likely to find mates among the birds on their new island. Birds feeding in the same area were then more likely to mate together than birds who have different diets, contributing to additional assortative mating. Together, these evolutionary mechanisms caused rapid speciation that allowed the new species to make the most of the various dietary niches (Figure 5.25).<\/p>\n<figure style=\"width: 619px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image24-1.png\" alt=\"A family tree of finches with different sized beaks.\" width=\"619\" height=\"325\" \/><figcaption class=\"wp-caption-text\">Figure 5.25: Darwin\u2019s finches demonstrating Adaptive Radiation. Credit: <a class=\"rId125\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-3\/\">Darwin\u2019s finches (Figure 4.20)<\/a> original to <a class=\"rId126\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a class=\"rId127\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">In today\u2019s modern world, understanding these evolutionary processes is crucial for developing immunizations and antibiotics that can keep up with the rapid mutation rate of viruses and bacteria. This is also relevant to our food supply, which relies, in large part, on the development of herbicides and pesticides that keep up with the mutation rates of pests and weeds. Viruses, bacteria, agricultural pests, and weeds have all shown great flexibility in developing alleles that make them resistant to the latest medical treatment, pesticide, or herbicide. Billion-dollar industries have specialized in trying to keep our species one step ahead of the next mutation in the pests and infectious diseases that put our survival at risk.<\/p>\n<h2>Cultural Connections and Contemporary Implications<\/h2>\n<h5>Sex within Culture and Biology<\/h5>\n<p>Research on bonobos (<em>Pan paniscus<\/em>) reveals a primate species whose social system relies heavily on affiliative and erotic behaviours rather than aggression. Bonobos live in fission\u2013fusion communities in Central African forests, where males remain in their natal groups and females migrate at adolescence. While sexual engagement is a large part of their social ecosystem, we see reproductive rates remain low, with females giving birth roughly every four to five years.<\/p>\n<p>Social cohesion among bonobos is strongly shaped by sexuality. Individuals engage frequently in diverse erotic behaviours; genital rubbing, oral contact, face-to-face copulation, and various forms of genital-to-genital stimulation are performed, but are not directly tied to reproduction. Through these modes of erotic sociality, tension is reduced, conflict is resolved, and food sharing is facilitated; all of which appear to function as peacemaking mechanisms integral to group stability. In this context, sexual pleasure is decoupled from reproduction, a parallel also found in human societies. Humans, like most primates, do not biologically mate for life; monogamy is a social contract, not a biological reality (Fuentes, 2012). Long-term exclusive mating is rare among primate species, and even in socially monogamous human groups, extra-pair copulations contribute substantially to reproductive outcomes.<\/p>\n<p>Human sexual development operates across genetic, hormonal, anatomical, and cultural levels. Biological traits such as chromosomal patterns or endocrine shifts interact with the social categories of gender, including transgender and transsexual identities (Fausto-Sterling, 1993, 2000a,b). Cultural expectations shape how sexual bodies are interpreted, often projecting ideological assumptions onto biological processes. This dynamic is exemplified in Emily Martin\u2019s (1991) critique of gendered metaphors in reproductive medical science, where egg and sperm are frequently described using stereotypically feminine or masculine language. Sexuality in humans is also neurologically mediated; as theorized by Freud, who suggested that humans possess undirected libidinal drives which society channels and constrains. With sex maintaining such sociocultural importance to humans, the anthropology of sex helps emphasize sexual practices, identities, and desires which emerge from the interplay of individual experience, interpersonal relationships, and broader cultural, political, and economic structures.<\/p>\n<h5>Archaeologies of Sexuality and the Future of Sex<\/h5>\n<p>Early archaeology commonly dismissed or obscured non-normative sexual imagery, classifying it under \u2018pornography\u2019 or \u2018Whore-Writing\u2019, a term introduced by the archaeologist M\u00fcller in 1850 to describe and demonize sexually explicit artifacts from Pompeii. Such categorizations reflected Victorian moral regimes rather than empirical assessment. Recent work highlights greater sexual and gender diversity in ancient material culture. Thousands of Ecuadorian clay figurines from 4400 BCE\u20131500 CE display non-binary and mixed-gender features, all of which were long-ignored or rationalized by earlier researchers (Ugalde, 2019). Later figurines exhibit more explicitly gendered poses, suggesting the gradual rise of patriarchal social structures.\u00a0<span style=\"margin: 0px;padding: 0px\">Simone de Beauvoir\u2019s\u00a0<em>The Second Sex<\/em> (1949) further explores this, arguing<\/span>\u00a0that women have historically been constructed as \u201cthe Other,\u201d a philosophical and social position that has shaped interpretations of sex, gender, and embodiment across cultures.<\/p>\n<p>Contemporary technological shifts prompt reconsideration of intimacy, embodiment, and sexual relationships. Robotics, avatars, and artificial companions raise questions about authenticity, relationality, and human\u2013machine attachment. Sherry Turkle (2011) argues that as people become increasingly anxious about interpersonal vulnerability, they may turn to machines for controlled forms of companionship and emotional safety. These developments illuminate broader transformations in how societies conceptualize relationships, desire, and human connection. They also challenge us to reconsider what counts as intimacy, what makes a relationship meaningful, and what ethical considerations arise when technologies substitute or reshape human sexual and emotional experience.<\/p>\n<h4>Discussion questions<\/h4>\n<ul>\n<li>With the rise of artificial companions, how might concepts such as intimacy, love, relationships, and sexuality be reconfigured? What might these changes reveal about how we understand human connection?<\/li>\n<li>How does studying sex and sexuality in other primates, such as bonobos, help us understand human sexuality and social behaviour? What are the limitations of using primates to understand humans?<\/li>\n<li>How might gendered metaphors and stereotypes influence the way scientific knowledge is produced and interpreted? Can you think of other examples where cultural assumptions have shaped scientific explanations?<\/li>\n<\/ul>\n<div class=\"textbox shaded\">\n<h2 class=\"import-Normal\">Review Questions<strong><br \/>\n<\/strong><\/h2>\n<ul>\n<li>Summarize the Modern Synthesis and provide several examples of how it is relevant to questions and problems in our world today.<\/li>\n<li>You inherit a house from a long-lost relative that contains a fancy aquarium, filled with a variety of snails. The phenotypes include large snails and small snails; red, black, and yellow snails; and solid, striped, and spotted snails. Devise a series of experiments that would help you determine how many snail species are present in your aquarium.<\/li>\n<li>Match the correct force of evolution with the correct real-world example:<br \/>\na. Mutationi. 5-alpha reductase deficiency<br \/>\nb. Genetic Driftii. Peppered Moths<br \/>\nc. Gene Flowiii. Neurofibromatosis Type 1<br \/>\nd. Natural Selectioniv. Scutellata Honey Bees<\/li>\n<li>Imagine a population of common house mice (<em>Mus musculus<\/em>). Draw a comic strip illustrating how mutation, genetic drift, gene flow, and natural selection might transform this population over several (or more) generations.<\/li>\n<li>\n<p class=\"import-Normal\">The many breeds of the single species of domestic dog (<em>Canis<\/em> <em>familiaris<\/em>) provide an extreme example of microevolution. Discuss why this is the case. What future scenarios can you imagine that could potentially transform the domestic dog into an example of macroevolution?<\/p>\n<\/li>\n<li>\n<p class=\"import-Normal\">The ability to roll one\u2019s tongue (lift the outer edges of the tongue to touch each other, forming a tube) is a dominant trait. In a small town of 1,500 people, 500 can roll their tongues. Use the Hardy-Weinberg formula to determine how many individuals in the town are homozygous dominant, heterozygous, and homozygous recessive.<\/p>\n<\/li>\n<\/ul>\n<\/div>\n<h2 class=\"import-Normal\">Key Terms<strong><br \/>\n<\/strong><\/h2>\n<p class=\"import-Normal\"><strong>5-alpha reductase deficiency<\/strong>: An autosomal recessive syndrome that manifests when a child having both X and Y sex chromosomes inherits two nonfunctional (mutated) copies of the SRD5A2 gene, producing a deficiency in a hormone necessary for development in infancy of typical male genitalia. These children often appear at birth to have female genitalia, but they develop a penis and other sexual characteristics when other hormones kick in during puberty.<\/p>\n<p class=\"import-Normal\"><strong>Adaptive radiation<\/strong>: The situation in which subgroups of a single species rapidly diversify and adapt to fill a variety of ecological niches.<\/p>\n<p class=\"import-Normal\"><strong>Admixture<\/strong>: A term often used to describe gene flow between human populations. Sometimes also used to describe gene flow between nonhuman populations.<\/p>\n<p class=\"import-Normal\"><strong>Allele frequency<\/strong>: The ratio, or percentage, of one allele compared to the other alleles for that gene within the study population.<\/p>\n<p class=\"import-Normal\"><strong>Alleles<\/strong>: Variant forms of genes.<\/p>\n<p class=\"import-Normal\"><strong>Allopatric speciation<\/strong>: Speciation caused by long-term isolation (physical separation) of subgroups of the population.<\/p>\n<p class=\"import-Normal\"><strong>Antibiotics<\/strong>: Medicines prescribed to treat bacterial infections.<\/p>\n<p class=\"import-Normal\"><strong>Artificial selection<\/strong>: Human-directed assortative mating among domestic animals, such as pets and livestock, designed to increase the chances of offspring having certain desirable traits.<\/p>\n<p class=\"import-Normal\"><strong>Asexual reproduction<\/strong>: Reproduction via mitosis, whereby offspring are clones of the parents.<\/p>\n<p class=\"import-Normal\"><strong>Autosomal dominant<\/strong>: A phenotype produced by a gene on an autosomal chromosome that is expressed, to the exclusion of the recessive phenotype, in heterozygotes.<\/p>\n<p class=\"import-Normal\"><strong>Autosomal recessive<\/strong>: A phenotype produced by a gene on an autosomal chromosome that is expressed only in individuals homozygous for the recessive allele.<\/p>\n<p class=\"import-Normal\"><strong>Balanced translocations<\/strong>: Chromosomal translocations in which the genes are swapped but no genetic information is lost.<\/p>\n<p class=\"import-Normal\"><strong>Balancing selection<\/strong>: A pattern of natural selection that occurs when the extremes of a trait are selected against, favouring the intermediate phenotype (a.k.a. stabilizing selection).<\/p>\n<p class=\"import-Normal\"><strong>Beneficial mutations<\/strong>: Mutations that produce some sort of an advantage to the individual.<\/p>\n<p class=\"import-Normal\"><strong>Benign<\/strong>: Noncancerous. Benign tumors may cause problems due to the area in which they are located (e.g., they might put pressure on a nerve or brain area), but they will not release cells that aggressively spread to other areas of the body.<\/p>\n<p class=\"import-Normal\"><strong>Caf\u00e9-au-lait spots (CALS)<\/strong>: Flat, brown birthmark-like spots on the skin, commonly associated with Neurofibromatosis Type 1.<\/p>\n<p class=\"import-Normal\"><strong>Chromosomal translocations<\/strong>: The transfer of DNA between nonhomologous chromosomes.<\/p>\n<p class=\"import-Normal\"><strong>Chromosomes<\/strong>: Molecules that carry collections of genes.<\/p>\n<p class=\"import-Normal\"><strong>Codons<\/strong>: Three-nucleotide units of DNA that function as three-letter \u201cwords,\u201d encoding instructions for the addition of one amino acid to a protein or indicating that the protein is complete.<\/p>\n<p class=\"import-Normal\"><strong>Cretaceous\u2013Paleogene extinction<\/strong>: A mass disaster caused by an asteroid that struck the earth approximately 66 million years ago and killed 75% of life on Earth, including all terrestrial dinosaurs. (a.k.a. K-Pg Extinction, Cretatious-Tertiary Extinction, and K-T Extinction).<\/p>\n<p class=\"import-Normal\"><strong>Crossover events<\/strong>: Chromosomal alterations that occur when DNA is swapped between homologous chromosomes while they are paired up during meiosis I.<\/p>\n<p class=\"import-Normal\"><strong>Cutaneous neurofibromas<\/strong>: Neurofibromas that manifest as spherical bumps on or just under the surface of the skin.<\/p>\n<p class=\"import-Normal\"><strong>Deleterious mutation<\/strong>: A mutation producing negative effects to the individual such as the beginnings of cancers or heritable disorders.<\/p>\n<p class=\"import-Normal\"><strong>Deletions<\/strong>: Mutations that involve the removal of one or more nucleotides from a DNA sequence.<\/p>\n<p class=\"import-Normal\"><strong>Derivative chromosomes<\/strong>: New chromosomal structures resulting from translocations.<\/p>\n<p class=\"import-Normal\"><strong><em>Dictyostelium discoideum<\/em><\/strong>: A species of social amoebae that has been widely used for laboratory research. Laboratory strains of <em>Dictyostelium discoideum <\/em>all carry mutations in the <em>NF1<\/em> gene, which is what allows them to survive on liquid media (agar) in Petri dishes.<\/p>\n<p class=\"import-Normal\"><strong>Directional selection<\/strong>: A pattern of natural selection in which one phenotype is favoured over the other, causing the frequencies of the associated advantageous alleles to gradually increase.<\/p>\n<p class=\"import-Normal\"><strong>Disruptive selection<\/strong>: A pattern of natural selection that occurs when both extremes of a trait are advantageous and intermediate phenotypes are selected against (a.k.a. diversifying selection).<\/p>\n<p class=\"import-Normal\"><strong>DNA repair mechanisms<\/strong>: Enzymes that patrol and repair DNA in living cells.<\/p>\n<p class=\"import-Normal\"><strong>DNA transposons<\/strong>: Transposons that are clipped out of the DNA sequence itself and inserted elsewhere in the genome.<\/p>\n<p class=\"import-Normal\"><strong>Ecological niche<\/strong>: A set of constraints and resources that are available in an environmental setting.<\/p>\n<p class=\"import-Normal\"><strong>Ellis-van Creveld syndrome<\/strong>: An autosomal recessive disorder characterized by short stature (dwarfism), polydactyly (the development of more than five digits [fingers or toes] on the hands or feet), abnormal tooth development, and heart defects. Estimated to affect approximately one in 60,000 individuals worldwide, among the Old Order Amish of Lancaster County, the rate is estimated to be as high as one in every 200 births.<\/p>\n<p class=\"import-Normal\"><strong>Evolution<\/strong>: A change in the allele frequencies in a population over time.<\/p>\n<p class=\"import-Normal\"><strong>Exons<\/strong>: The DNA sequences within a gene that directly encode protein sequences. After being transcribed into messenger RNA, the introns (DNA sequences within a gene that do not directly encode protein sequences) are clipped out, and the exons are pasted together prior to translation.<\/p>\n<p class=\"import-Normal\"><strong>Fertile offspring<\/strong>: Offspring that can successfully reproduce, resulting in offspring of their own.<\/p>\n<p class=\"import-Normal\"><strong>Founder effect<\/strong>: A type of genetic drift that occurs when members of a population leave the main or \u201cparent\u201d group and form a new population that no longer interbreeds with the other members of the original group.<\/p>\n<p class=\"import-Normal\"><strong>Frameshift mutations<\/strong>: Types of indels that involve the insertion or deletion of any number of nucleotides that is not a multiple of three. These \u201cshift the reading frame\u201d and cause all codons beyond the mutation to be misread.<\/p>\n<p class=\"import-Normal\"><strong>Gametes<\/strong>: The reproductive cells, produced through meiosis (a.k.a. germ cells or sperm or egg cells).<\/p>\n<p class=\"import-Normal\"><strong>Gene<\/strong>: A sequence of DNA that provides coding information for the construction of proteins.<\/p>\n<p class=\"import-Normal\"><strong>Gene flow<\/strong>: The movement of alleles from one population to another. This is one of the forces of evolution.<\/p>\n<p class=\"import-Normal\"><strong>Gene pool<\/strong>: The entire collection of genetic material in a breeding community that can be passed on from one generation to the next.<\/p>\n<p class=\"import-Normal\"><strong>Genetic drift<\/strong>: Random changes in allele frequencies within a population from one generation to the next. This is one of the forces of evolution.<\/p>\n<p class=\"import-Normal\"><strong>Genotype<\/strong>: The set of alleles that an individual has for a given gene.<\/p>\n<p class=\"import-Normal\"><strong>Genotype frequencies<\/strong>: The ratios or percentages of the different homozygous and heterozygous genotypes in the population.<\/p>\n<p class=\"import-Normal\"><strong><em>Guevedoces<\/em><\/strong>: The term coined locally in the Dominican Republic for the condition scientifically known as 5-alpha reductase deficiency. The literal translation is \u201cpenis at twelve.\u201d<\/p>\n<p class=\"import-Normal\"><strong>Hardy-Weinberg Equilibrium<\/strong>: A mathematical formula (<em>1=p<\/em><sup><em>2<\/em><\/sup><em> + 2pq + q<\/em><sup><em>2<\/em><\/sup> ) that allows estimation of the number and distribution of dominant and recessive alleles in a population.<\/p>\n<p class=\"import-Normal\"><strong>Harlequin ladybeetle<\/strong>: A species of ladybeetle, native to East Asia, that was introduced to Europe and the Americas as a form of pest control. After many decades of use, one of the North American strains developed the ability to reproduce in diverse environments, causing it to spread rapidly throughout the Americas, Europe, and Africa. It has hybridized with European strains and is now a major pest in its own right.<\/p>\n<p class=\"import-Normal\"><strong>Heterozygous genotype<\/strong>: A genotype comprising two different alleles.<\/p>\n<p class=\"import-Normal\"><strong>Homozygous genotype<\/strong>: A genotype comprising an identical set of alleles.<\/p>\n<p class=\"import-Normal\"><strong>Hybridization<\/strong>: A term often used to describe gene flow between nonhuman populations.<\/p>\n<p class=\"import-Normal\"><strong>Inbreeding<\/strong>: The selection of mates exclusively from within a small, closed population.<\/p>\n<p class=\"import-Normal\"><strong>Indels<\/strong>: A class of mutations that includes both insertions and deletions.<\/p>\n<p class=\"import-Normal\"><strong>Inherited mutation<\/strong>: A mutation that has been passed from parent to offspring.<\/p>\n<p class=\"import-Normal\"><strong>Insertions<\/strong>: Mutations that involve the addition of one or more nucleotides into a DNA sequence.<\/p>\n<p class=\"import-Normal\"><strong>Isolation<\/strong>: Prevention of a population subgroup from breeding with other members of the same species due to a physical barrier or, in humans, a cultural rule.<\/p>\n<p class=\"import-Normal\"><strong>Last Universal Common Ancestor (LUCA)<\/strong>: The ancient organism from which all living things on Earth are descended.<\/p>\n<p class=\"import-Normal\"><strong>Macroevolution<\/strong>: Changes that result in the emergence of new species, how the similarities and differences between species, as well as the phylogenetic relationships with other taxa, lead to changes that result in the emergence of new species.<\/p>\n<p class=\"import-Normal\"><strong>Malaria<\/strong>: A frequently deadly mosquito-borne disease caused by infection of the blood by a <em>Plasmodium<\/em> parasite.<\/p>\n<p class=\"import-Normal\"><strong>Malignant<\/strong>: Cancerous. Malignant tumors grow aggressively and their cells may metastasize (travel through the blood or lymph systems) to form new, aggressive tumors in other areas of the body.<\/p>\n<p class=\"import-Normal\"><strong>Microevolution<\/strong>: Changes in allele frequencies within breeding populations\u2014that is, within a single species.<\/p>\n<p class=\"import-Normal\"><strong>Modern Synthesis<\/strong>: The integration of Darwin\u2019s, Mendel\u2019s, and subsequent research into a unified theory of evolution.<\/p>\n<p class=\"import-Normal\"><strong>Monosomies<\/strong>: Conditions resulting from a nondisjunction event, in which a cell ends up with only one copy of a chromosome. In humans, a single X chromosome is the only survivable monosomy.<\/p>\n<p class=\"import-Normal\"><strong>Mutation<\/strong>: A change in the nucleotide sequence of the genetic code. This is one of the forces of evolution.<\/p>\n<p class=\"import-Normal\"><strong>Natural selection<\/strong>: An evolutionary process that occurs when certain phenotypes confer an advantage or disadvantage in survival and\/or reproductive success. This is one of the forces of evolution, and it was first identified by Charles Darwin.<\/p>\n<p class=\"import-Normal\"><strong>Negative assortative mating<\/strong>: A pattern that occurs when individuals tend to select mates with qualities different from their own.<\/p>\n<p class=\"import-Normal\"><strong>Neurofibromas<\/strong>: Nerve sheath tumors that are common symptoms of Neurofibromatosis Type 1.<\/p>\n<p class=\"import-Normal\"><strong>Neurofibromatosis Type 1<\/strong>: An autosomal dominant genetic disorder affecting one in every 3,000 people. It is caused by mutation of the <em>NF1<\/em> gene on Chromosome 17, resulting in a defective neurofibromin protein. The disorder is characterized by neurofibromas, caf\u00e9-au-lait spots, and a host of other potential symptoms.<\/p>\n<p class=\"import-Normal\"><strong>NF1<\/strong>: An abbreviation for Neurofibromatosis Type 1. When italicized, <em>NF1 <\/em>refers to the gene on Chromosome 17 that encodes the neurofibromin protein.<\/p>\n<p class=\"import-Normal\"><strong>Nondisjunction events<\/strong>: Chromosomal abnormalities that occur when the homologous chromosomes (in meiosis I) or sister chromatids (in meiosis II and mitosis) fail to separate after pairing. The result is that both chromosomes or chromatids end up in the same daughter cell, leaving the other daughter cell without any copy of that chromosome.<\/p>\n<p class=\"import-Normal\"><strong>Nonrandom mating<\/strong>: A scenario in which mate choice within a population follows a nonrandom pattern (a.k.a. assortative mating).<\/p>\n<p class=\"import-Normal\"><strong>Nonsynonymous mutation<\/strong>: A point mutation that causes a change in the resulting protein.<\/p>\n<p class=\"import-Normal\"><strong>Old Order Amish<\/strong>: A culturally isolated population in Lancaster County, Pennsylvania, that has approximately 50,000 current members, all of whom can trace their ancestry back to a group of approximately eighty individuals. This group has high rates of certain genetics disorders, including Ellis-van Creveld syndrome.<\/p>\n<p class=\"import-Normal\"><strong>Origins of life<\/strong>: How the first living organism came into being.<\/p>\n<p class=\"import-Normal\"><strong>Peacock<\/strong>: The male sex of the peafowl, famous for its large, colourful tail, which it dramatically displays to attract mates. (The female of the species is known as a peahen.)<\/p>\n<p class=\"import-Normal\"><strong>Peppered moth<\/strong>: A species of moth (<em>Biston betularia<\/em>) found in England that has light and dark phenotypes. During the Industrial Revolution, when soot blackened the trees, the frequency of the previously rare dark phenotype dramatically increased, as lighter-coloured moths were easier for birds to spot against the sooty trees. After environmental regulations eliminated the soot, the lighter-coloured phenotype gradually became most common again.<\/p>\n<p class=\"import-Normal\"><strong>Phenotype<\/strong>: The observable traits that are produced by a genotype.<\/p>\n<p class=\"import-Normal\"><strong>Phylogenetic tree of life<\/strong>: A family tree of all living organisms, based on genetic relationships.<\/p>\n<p class=\"import-Normal\"><strong>Phylogenies<\/strong>: Genetically determined family lineages.<\/p>\n<p class=\"import-Normal\"><strong><em>Plasmodium<\/em><\/strong>: A genus of mosquito-borne parasite. Several <em>Plasmodium<\/em> species cause malaria when introduced to the human bloodstream via a mosquito bite.<\/p>\n<p class=\"import-Normal\"><strong>Plexiform neurofibromas<\/strong>: Neurofibromas that involve whole branches of nerves, often giving the appearance that the surface of the skin is \u201cmelting.\u201d<\/p>\n<p class=\"import-Normal\"><strong>Point mutation<\/strong>: A single-letter (single-nucleotide) change in the genetic code, resulting in the substitution of one nucleic acid base for a different one.<\/p>\n<p class=\"import-Normal\"><strong>Polymorphisms<\/strong>: Multiple forms of a trait; alternative phenotypes within a given species.<\/p>\n<p class=\"import-Normal\"><strong>Population<\/strong>: A group of individuals who are genetically similar enough and geographically near enough to one another that they can breed and produce new generations of individuals.<\/p>\n<p class=\"import-Normal\"><strong>Population bottleneck<\/strong>: A type of genetic drift that occurs when the number of individuals in a population drops dramatically due to some random event.<\/p>\n<p class=\"import-Normal\"><strong>Positive assortative mating<\/strong>: A pattern that results from a tendency for individuals to mate with others who share similar phenotypes.<\/p>\n<p class=\"import-Normal\"><strong>Retrotransposons<\/strong>: Transposons that are transcribed from DNA into RNA, and then are \u201creverse transcribed,\u201d to insert the copied sequence into a new location in the DNA.<\/p>\n<p class=\"import-Normal\"><strong>Scutellata honey bees<\/strong>: A strain of honey bees that resulted from the hybridization of African and European honey bee subspecies. These bees were accidentally released into the wild in 1957 in Brazil and have since spread throughout South and Central America and into the United States. Also known as \u201ckiller bees,\u201d they tend to be very aggressive in defence of their hives and have caused many fatal injuries to humans and livestock.<\/p>\n<p class=\"import-Normal\"><strong>Sexual reproduction<\/strong>: Reproduction via meiosis and combination of gametes. Offspring inherit genetic material from both parents.<\/p>\n<p class=\"import-Normal\"><strong>Sexual selection<\/strong>: An aspect of natural selection in which the selective pressure specifically affects reproductive success (the ability to successfully breed and raise offspring).<\/p>\n<p class=\"import-Normal\"><strong>Sickle cell anemia<\/strong>: An autosomal recessive genetic disorder that affects millions of people worldwide. It is most common in Africa, countries around the Mediterranean Sea, and eastward as far as India. Homozygotes for the recessive allele develop the disorder, which produce misshapen red blood cells that cause iron deficiency, painful episodes of oxygen-deprivation in localized tissues, and a host of other symptoms. In heterozygotes, though, the sickle cell allele confers a greater resistance to malaria.<\/p>\n<p class=\"import-Normal\"><strong>Somatic cells<\/strong>: The cells of our organs and other body tissues (all cells except gametes) that replicate by mitosis.<\/p>\n<p class=\"import-Normal\"><strong>Speciation<\/strong>: The process by which a single population divides into two or more separate species.<\/p>\n<p class=\"import-Normal\"><strong>Species<\/strong>: Organisms whose individuals are capable of breeding because they are biologically and behaviourally compatible to produce viable, fertile offspring.<\/p>\n<p class=\"import-Normal\"><strong>Spontaneous mutation<\/strong>: A mutation that occurs due to random chance or unintentional exposure to mutagens. In families, a spontaneous mutation is the first case, as opposed to mutations that are inherited from parents.<\/p>\n<p class=\"import-Normal\"><strong>Subspecies<\/strong>: A distinct subtype of a species. Most often, this is a geographically isolated population with unique phenotypes; however, it remains biologically and behaviourally capable of interbreeding with other populations of the same species.<\/p>\n<p class=\"import-Normal\"><strong>Sympatric speciation<\/strong>: When a population splits into two or more separate species while remaining located together without a physical (or cultural) barrier.<\/p>\n<p class=\"import-Normal\"><strong>Synonymous mutation<\/strong>: A point mutation that does not change the resulting protein.<\/p>\n<p class=\"import-Normal\"><strong>Transposable elements<\/strong>: Fragments of DNA that can \u201cjump\u201d around in the genome.<\/p>\n<p class=\"import-Normal\"><strong>Transposon<\/strong>: Another term for \u201ctransposable element.\u201d<\/p>\n<p class=\"import-Normal\"><strong>Trisomies<\/strong>: Conditions in which three copies of the same chromosome end up in a cell, resulting from a nondisjunction event. Down syndrome, Edwards syndrome, and Patau syndrome are trisomies.<\/p>\n<p class=\"import-Normal\"><strong>Unbalanced translocations<\/strong>: Chromosomal translocations in which there is an unequal exchange of genetic material, resulting in duplication or loss of genes.<\/p>\n<p class=\"import-Normal\"><strong>UV crosslinking<\/strong>: A type of mutation in which adjacent thymine bases bind to one another in the presence of UV light.<\/p>\n<p class=\"import-Normal\"><strong>Viable offspring<\/strong>: Offspring that are healthy enough to survive to adulthood.<\/p>\n<p class=\"import-Normal\"><strong>Xeroderma pigmentosum<\/strong>: An autosomal recessive disease in which DNA repair mechanisms do not function correctly, resulting in a host of problems especially related to sun exposure, including severe sunburns, dry skin, heavy freckling, and other pigment changes.<\/p>\n<h2 class=\"import-Normal\">For Further Exploration<\/h2>\n<p>Explore Evolution on <a href=\"https:\/\/www.hhmi.org\/biointeractive\/evolution-collection\">HHMI\u2019s Biointeractive website<\/a>.<\/p>\n<p>Teaching Evolution through <a href=\"https:\/\/humanorigins.si.edu\/education\/teaching-evolution-through-human-examples\">Human Examples, Smithsonian Museum of Natural History websites<\/a>.<\/p>\n<h2 class=\"import-Normal\">References<\/h2>\n<p class=\"import-Normal\">Bloomfield, Gareth, David Traynor, Sophia P. Sander, Douwe M. Veltman, Justin A. Pachebat, and Robert R. Kay. 2015. \u201cNeurofibromin Controls Macropinocytosis and Phagocytosis in <em>Dictyostelium<\/em>.\u201d <em>eLife<\/em> 4:e04940.<\/p>\n<p class=\"import-Normal\">Chaix, Rapha\u00eblle, Chen Cao, and Peter Donnelly. 2008. \u201cIs Mate Choice in Humans MHC-Dependent?\u201d <em>PLoS Genetics<\/em> 4 (9): e1000184.<\/p>\n<p class=\"import-Normal\">Cook, Laurence M. 2003. \"The Rise and Fall of the <em>Carbonaria<\/em> Form of the Peppered Moth.\" <em>The Quarterly Review of Biology<\/em> 78 (4): 399\u2013417.<\/p>\n<p class=\"import-Normal\">Cota, Bruno C\u00e9zar Lage, Jo\u00e3o Gabriel Marques Fonseca, Luiz Oswaldo Carneiro Rodrigues, Nilton Alves de Rezende, Pollyanna Barros Batista, Vincent Michael Riccardi, and Luciana Macedo de Resende. 2018. \u201cAmusia and Its Electrophysiological Correlates in Neurofibromatosis Type 1.\u201d <em>Arquivos de Neuro-Psiquiatria<\/em> 76 (5): 287\u2013295.<\/p>\n<p class=\"import-Normal\">D\u2019Asdia, Maria Cecilia, Isabella Torrente, Federica Consoli, Rosangela Ferese, Monia Magliozzi, Laura Bernardini, Valentina Guida, et al. 2013. \u201cNovel and Recurrent EVC and EVC2 Mutations in Ellis-van Creveld Syndrome and Weyers Acrofacial Dyostosis.\u201d <em>European Journal of Medical Genetics<\/em> 56 (2): 80\u201387.<\/p>\n<p>de Beauvoir, S. (2009). <em>The Second Sex<\/em> (C. Borde &amp; S. Malovany-Chevallier, Trans.). Vintage Books. (Original work published 1949)<\/p>\n<p class=\"import-Normal\">Dobzhansky, Theodosius. 1937. <em>Genetics and the Origin of Species. <\/em>Columbia University Biological Series. New York: Columbia University Press.<\/p>\n<p class=\"import-Normal\">Facon, Beno\u00eet, Laurent Crespin, Anne Loiseau, Eric Lombaert, Alexandra Magro, and Arnaud Estoup. 2011. \u201cCan Things Get Worse When an Invasive Species Hybridizes? The Harlequin Ladybird <em>Harmonia axyridis<\/em> in France as a Case Study.\u201d <em>Evolutionary Applications<\/em> 4 (1): 71\u201388.<\/p>\n<p>Fausto-Sterling, A. (1993). The five sexes: Why male and female are not enough. <em>The Sciences;<\/em> 33(2):20\u201325.<\/p>\n<p>Fausto-Sterling, A. (2000a). The Five Sexes Revisited. <em>The Sciences; <\/em>40(4):18-23<\/p>\n<p>Fausto-Sterling, A. (2000b). <em>Sexing the body: Gender politics and the construction of sexuality<\/em>. Basic Books.<\/p>\n<p class=\"import-Normal\">Fisher, Ronald A. 1919. \"The Correlation between Relatives on the Supposition of Mendelian Inheritance.\" <em>Transactions of the Royal Society of Edinburgh<\/em> 52 (2): 399\u2013433.<\/p>\n<p class=\"import-Normal\">Ford, E. B. 1942. <em>Genetics for Medical Students<\/em>. London: Methuen.<\/p>\n<p class=\"import-Normal\" style=\"background-color: #ffffff\">Ford, E. B. 1949. <em>Mendelism and Evolution<\/em>. London: Methuen.<\/p>\n<p>Fuentes, A. (2012). <em>Race, monogamy, and other lies they told you: Busting myths about human nature<\/em>. University of California Press.<\/p>\n<p class=\"import-Normal\">Grant, Bruce S. 1999. \u201cFine-tuning the Peppered Moth Paradigm.\u201d <em>Evolution<\/em> 53 (3): 980\u2013984.<\/p>\n<p class=\"import-Normal\">Haldane, J. B. S. 1924. \u201cA Mathematical Theory of Natural and Artificial Selection (Part 1).\u201d <em>Transactions of the Cambridge Philosophical Society<\/em> 23 (2):19\u201341.<\/p>\n<p>Hoelzel, A. R., Gkafas, G. A., Kang, H., Sarigol, F., Le Boeuf, B., Costa, D. P., Beltran, R. S., Reiter, J., Robinson, P. W., McInerney, N., Seim, I., Sun, S., Fan, G., &amp; Li, S. (2024). Genomics of post-bottleneck recovery in the northern elephant seal. Nature Ecology &amp; Evolution, 8, 686\u2013694. https:\/\/doi.org\/10.1038\/s41559-024-02337-4<\/p>\n<p>Hurst, L. D. (1996). Why are there only two sexes? <em>Proceedings of the Royal Society, London B<\/em>, 263; 415-422.<\/p>\n<p class=\"import-Normal\">Imperato-McGinley, J., and Y.-S. Zhu. 2002. \u201cAndrogens and Male Physiology: The Syndrome of 5 Alpha-Reductase-2 Deficiency.\u201d <em>Molecular and Cellular Endocrinology <\/em>198 (1-2): 51\u201359.<\/p>\n<p class=\"import-Normal\">Jablonski, David, and W. G. Chaloner. 1994. \"Extinctions in the Fossil Record.\u201d <em>Philosophical Transactions of the Royal Society of London B: Biological Sciences<\/em> 344 (1307): 11\u201317.<\/p>\n<p>Kinsey, A. C., Pomeroy, W. B., &amp; Martin, C. E. (1948). <em>Sexual behavior in the human male<\/em>. W.B. Saunders.<\/p>\n<p>Kinsey, A. C., Pomeroy, W. B., Martin, C. E., &amp; Gebhard, P. H. (1953). <em>Sexual behavior in the human female<\/em>. W.B. Saunders.<\/p>\n<p class=\"import-Normal\">Livi-Bacci, Massimo. 2006. \u201cThe Depopulation of Hispanic America after the Conquest.\u201d <em>Population Development and Review<\/em> 32 (2): 199\u2013232.<\/p>\n<p class=\"import-Normal\">Lombaert, Eric, Thomas Guillemaud, Jean-Marie Cornuet, Thibaut Malausa, Beno\u00eet Facon, and Arnaud Estoup. 2010. \"Bridgehead Effect in the Worldwide Invasion of the Biocontrol Harlequin Ladybird.\u201d <em>PLoS ONE<\/em> 5 (3): e9743.<\/p>\n<p>Martin, E. (1991). The egg and the sperm: How science has constructed a romance based on stereotypical male\u2013female roles. <em>Signs,<\/em> 16(3), 485\u2013501.<\/p>\n<p class=\"import-Normal\">Martins, Aline Stangherlin, Ann Kristine Jansen, Luiz Oswaldo Carneiro Rodrigues, Camila Maria Matos, Marcio Leandro Ribeiro Souza, Juliana Ferreira de Souza, Maria de F\u00e1tima Haueisen Sander Diniz, et al. 2016. \u201cLower Fasting Blood Glucose in Neurofibromatosis Type 1.\u201d <em>Endocrine Connections<\/em> 5 (1): 28\u201333.<\/p>\n<p class=\"import-Normal\">Pickering, Gary, James Lin, Roland Riesen, Andrew Reynolds, Ian Brindle, and George Soleas. 2004. \"Influence of <em>Harmonia axyridis<\/em> on the Sensory Properties of White and Red Wine.\" <em>American Journal of Enology and Viticulture<\/em> 55 (2): 153\u2013159.<\/p>\n<p class=\"import-Normal\">Repunte-Canonigo Vez, Melissa A. Herman, Tomoya Kawamura, Henry R. Kranzler, Richard Sherva, Joel Gelernter, Lindsay A. Farrer, Marisa Roberto, and Pietro Paolo Sanna. 2015. \u201cNF1 Regulates Alcohol Dependence-Associated Excessive Drinking and Gamma-Aminobutyric Acid Release in the Central Amygdala in Mice and Is Associated with Alcohol Dependence in Humans.\u201d <em>Biological Psychiatry<\/em> 77 (10): 870\u2013879.<\/p>\n<p class=\"import-Normal\">Riccardi, Vincent M. 1992. <em>Neurofibromatosis: Phenotype, Natural History, and Pathogenesis.<\/em> Baltimore: Johns Hopkins University Press.<\/p>\n<p class=\"import-Normal\">Sanford, Malcolm T. 2006. \"The Africanized Honey Bee in the Americas: A Biological Revolution with Human Cultural Implications, Part V\u2014Conclusion.\" <em>American Bee Journal <\/em>146 (7): 597\u2013599.<\/p>\n<p class=\"import-Normal\">Sanna, Pietro Paolo, Cindy Simpson, Robert Lutjens, and George Koob. 2002. \u201cERK Regulation in Chronic Ethanol Exposure and Withdrawal.\u201d <em>Brain Research<\/em> 948 (1\u20132): 186\u2013191.<\/p>\n<p>Turkle, S. (2011). <em>Alone together: Why we expect more from technology and less from each other<\/em>. Basic Books.<\/p>\n<p>Ugalde, Mar\u00eda Fernanda. 2019. \u201cThe Rebel Potters: A Review of Gender Relations, Female Oppression, and Patriarchy from the Perspective of Ecuadorian Archaeology.\u201d Translated by Tiziana Laudato. <em>Ant\u00edpoda. Revista de Antropolog\u00eda y Arqueolog\u00eda<\/em> 36: 1-23. https:\/\/doi.org\/10.7440\/antipoda36.2019.03<\/p>\n<p>Weber, DianaS., Stewart, B. S., Garza, J. Carlos., &amp; Lehman, N. (2000). An empirical genetic assessment of the severity of the northern elephant seal population bottleneck. Current Biology, 10(20), 1287\u20131290. https:\/\/doi.org\/10.1016\/s0960-9822(00)00759-4<\/p>\n<p class=\"import-Normal\">World Health Organization. 1996. \u201cControl of Hereditary Disorders: Report of WHO Scientific meeting (1996).\u201d WHO Technical Reports 865. Geneva: World Health Organization.<\/p>\n<p class=\"import-Normal\">World Health Organization. 2017. \u201cGlobal Priority List of Antibiotic-Resistant Bacteria to Guide Research, Discovery, and Development of New Antibiotics.\u201d Global Priority Pathogens List, February 27. Geneva: World Health Organization. https:\/\/www.who.int\/medicines\/publications\/WHO-PPL-Short_Summary_25Feb-ET_NM_WHO.pdf.<\/p>\n<p class=\"import-Normal\">Wright, Sewall. 1932. \"The Roles of Mutation, Inbreeding, Crossbreeding, and Selection in Evolution.\" <em>Proceedings of the Sixth International Congress on Genetics<\/em> 1 (6): 356\u2013366.<\/p>\n<h2 class=\"import-Normal\">Acknowledgement<strong><br \/>\n<\/strong><\/h2>\n<p class=\"import-Normal\">Many thanks to Dr. Vincent M. Riccardi for sharing his vast knowledge of neurofibromatosis and for encouraging me to explore it from an anthropological perspective.<\/p>\n<\/div>\n<\/div>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1695_1853\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1695_1853\"><div tabindex=\"-1\"><div class=\"__UNKNOWN__\">\n<div class=\"textbox\">\n<p>Learn more about <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/about-the-authors\/\">authors and editors<\/a>,<a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/student-contributors\/\"> Hess' student contributions<\/a>, and <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/versioning-history\/\">versioning history<\/a>.<\/p>\n<\/div>\n<div class=\"textbox textbox--learning-objectives\">\n<header class=\"textbox__header\">\n<h2 class=\"textbox__title\">Learning Objectives<\/h2>\n<\/header>\n<div class=\"textbox__content\">\n<ul>\n<li class=\"import-Normal\">Describe how studying nonhuman primates is important in anthropology.<\/li>\n<li class=\"import-Normal\">Compare two ways of categorizing taxa: grades and clades.<\/li>\n<li class=\"import-Normal\">Define different types of traits used to evaluate primate taxa.<\/li>\n<li class=\"import-Normal\">Identify key ways that primates differ from other mammals.<\/li>\n<li class=\"import-Normal\">Distinguish between the major primate taxa using their key characteristics.<\/li>\n<li class=\"import-Normal\">Describe your place in nature by learning your taxonomic classification.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<p class=\"import-Normal\">You may be wondering why a field dedicated to the study of humans includes discussions of nonhuman animals. Our primary goal in biological anthropology is to understand how humans are similar to and different from the rest of the natural world, why we have the traits we have, and how we got to be the way we are. But to fully grasp our place in nature, we must look to our closest living relatives, the nonhuman primates. In this chapter, we focus on the organization and diversity within the Order Primates.<\/p>\n<h2 class=\"import-Normal\">Studying Primates in Biological Anthropology<\/h2>\n<p class=\"import-Normal\">Primates are one of at least twenty Orders belonging to the Class Mammalia, and probably one of the oldest. One genetic estimate puts the origin of primates at approximately 91 million years ago (mya), predating the extinction of the dinosaurs (Bininda-Emonds Et al. 2007). Today, the Order Primates is a diverse group of animals that includes lemurs and lorises, tarsiers, monkeys, apes, and humans, all of which are united in sharing a suite of anatomical, behavioural, and life history characteristics. While nonhuman primates are fascinating animals in their own right, their close relationship to humans makes them ideal for studying humans via <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_944\">homology<\/a>, <\/strong>looking at traits that are shared between taxa because they inherited the trait from a common ancestor. For example, humans (genus <em>Homo<\/em>) and chimpanzees (genus <em>Pan<\/em>) both share the trait of male cooperation in hunting. This trait\u2014along with many others that chimpanzees and humans share\u2014is likely homologous<em>, <\/em>meaning it was probably passed down from the last common ancestor of <em>Homo<\/em> and <em>Pan, <\/em>which lived about 6\u20138 million years ago.<\/p>\n<p class=\"import-Normal\">Nonhuman primates also make excellent comparators for learning about humans via <strong>analogy<\/strong>. Many nonhuman primates live in environments similar to those in which our ancestors lived and therefore exhibit traits similar to what we see in humans. For example, baboons and humans both have long legs. In humans, this is because about 1.7 million years ago, our ancestors moved into savanna habitats where longer legs helped them move more efficiently over long distances. Baboons, who also live in savanna habitats, independently evolved longer arms and legs for the same reason\u2014to be able to cover more ground, more efficiently. This means that having long legs is an analogous trait in baboons and humans: \u2014that is, this adaptation evolved independently in the two species but for the same purpose. Using homology and analogy, our closest living relatives provide the critical context in which to understand human biology, morphology, and behaviour. It is only by studying how humans compare with our primate relatives that we can fully comprehend our place in nature.<\/p>\n<h3 class=\"import-Normal\"><strong>Ways of Organizing Taxa<\/strong><\/h3>\n<p class=\"import-Normal\">You learned in Chapter 2 about Linnaeus and the hierarchical nature of taxonomic classification. Our goal in classifying taxa is to create categories that reflect clade relationships. A <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1116\">clade<\/a> <\/strong>is a grouping of organisms based on relatedness that reflects a branch of the evolutionary tree. Clade relationships are determined using traits shared by groups of taxa as well as genetic similarities. An example of a clade would be a grouping that includes humans, chimpanzees, bonobos, and gorillas (Figure 6.1). These taxa are in what is referred to as the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1118\">African clade<\/a><\/strong> of hominoids (a taxonomic group you will learn about later in this chapter). The African clade grouping reflects how humans, chimpanzees, bonobos, and gorillas all share a more recent ancestor with each other than any of them do with other species\u2014that is, we are on the same branch of the evolutionary tree. We know members of the African clade are most closely related based on shared morphological traits as well as genetic similarities. Excluded from this grouping is the orangutan, which is considered a member of the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1120\">Asian clade<\/a><\/strong> of hominoids.<\/p>\n<figure style=\"width: 800px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2023\/06\/image1-3.jpg\" alt=\"Diagram shows large-bodied hominoids grouped by grade or clade.\" width=\"800\" height=\"358\" \/><figcaption class=\"wp-caption-text\">Figure 6.1: Grades vs. Clades. A grade grouping of apes places orangutans, gorillas, chimpanzees, and bonobos together based on their similar appearance and lifestyle, but excludes humans. Clade classification is based on shared derived traits and genetic evidence (both reflecting close evolutionary relationships). A clade grouping of apes places humans with gorillas, chimpanzees, and bonobos., whereas orangutans are separated. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\" target=\"_blank\">Grades vs. clades comparison (Figure 5.12)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\" target=\"_blank\">CC BY-NC-SA 4.0 License<\/a>. [Includes <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Orangutan_on_a_tree_(Unsplash).jpg\" target=\"_blank\">Orangutan on a tree (Unsplash)<\/a> by Dawn Armfield, <a href=\"https:\/\/creativecommons.org\/publicdomain\/zero\/1.0\/legalcode\" target=\"_blank\">public domain (CC0 1.0)<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Gorilla_Profile_(17997840570).jpg\" target=\"_blank\">Gorilla Profile (17997840570)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/100915417@N07\" target=\"_blank\">Charlie Marshall<\/a> from Bristol UK, modified (cropped), <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/legalcode\" target=\"_blank\">CC BY 2.0 License<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Chimpanzee_(14679767561).jpg\" target=\"_blank\">Chimpanzee (14679767561)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/120374925@N06\" target=\"_blank\">Magnus Johansson<\/a>, modified (cropped), <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\" target=\"_blank\">CC BY-SA 2.0<\/a>; <a href=\"https:\/\/pixabay.com\/photos\/pointing-finger-hand-pointing-1922074\/\" target=\"_blank\">Pointing finger (1922074)<\/a> by <a href=\"https:\/\/pixabay.com\/users\/truthseeker08-2411480\/\" target=\"_blank\">truthseeker08<\/a>, <a href=\"https:\/\/pixabay.com\/service\/terms\/#license\" target=\"_blank\">Pixabay License<\/a>.]<\/figcaption><\/figure>\n<p class=\"import-Normal\">In contrast, <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1122\">grades<\/a> <\/strong>are groupings that reflect levels of adaptation or overall similarity and not necessarily evolutionary relationships. An example of a grade would be placing orangutans, gorillas, bonobos, and chimpanzees into a group, and excluding humans. Grouping in this way is based on the superficial similarities of the apes in being large-bodied, having lots of body hair, living in tropical forests, climbing and sleeping in trees, and so on. According to these criteria, humans seem to be unusual in that we differ in our morphology, behaviour, and ecology. Separating humans from the large-bodied apes is the system that was used historically. We now know that grouping orangutans, gorillas, bonobos, and chimpanzees and excluding humans does not accurately reflect our true evolutionary relationships. Since our goal in taxonomic classification is to organize animals to reflect their evolutionary relationships, we prefer to use clade classifications.<\/p>\n<h3 class=\"import-Normal\"><strong>Types of Traits<\/strong><\/h3>\n<p class=\"import-Normal\">When evaluating relationships between taxa, we use key traits that allow us to determine which species are most closely related to one another. Traits can be either ancestral or derived. <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1124\">Ancestral traits<\/a><\/strong> are those that a taxon has because it has inherited the trait from a distant ancestor. For example, all primates have body hair because we are mammals and all mammals share an ancestor hundreds of millions of years ago that had body hair. This trait has been passed down to all mammals from a shared ancestor, so all mammals alive today have body hair. <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1126\">Derived traits<\/a><\/strong> are those that have been more recently altered. This type of trait is most useful when we are trying to distinguish one group from another because derived traits tell us which taxa are more closely related to each other. For example, humans walk on two legs.The many adaptations that humans possess that allow us to move in this way evolved after humans split from the Genus <em>Pan<\/em>. This means that when we find fossil taxa that share derived traits for walking on two legs, we can conclude that they are likely more closely related to humans than to chimpanzees and bonobos<em>. <\/em><\/p>\n<p class=\"import-Normal\">There are a couple of other important points about ancestral and derived traits that will become apparent as we discuss primate diversity. First, the terms <em>ancestral<\/em> and <em>derived<\/em> are relative terms, meaning that a trait can be either one depending on the taxa being compared. For example, in the previous paragraph, body hair was used as an example for an ancestral trait among primates. All mammals have body hair because we share a distant ancestor who had this trait. The presence of body hair therefore doesn\u2019t allow you to distinguish whether monkeys are more closely related to apes or lemurs because they all share this trait. However, if we are comparing mammals to birds and fish, then body hair becomes a derived trait of mammals. It evolved after mammals diverged from birds and fish, and it tells us that all mammals are more closely related to each other than they are to birds or fish.The second important point is that very often when one lineage splits into two, one taxon will stay more similar to the last common ancestor in retaining more ancestral traits, whereas the other lineage will usually become more different from the last common ancestor by developing more derived traits. This will become very apparent when we discuss the two suborders of primates, Strepsirrhini and Haplorrhini. When these two lineages diverged, strepsirrhines retained more ancestral traits (those present in the earliest primates) and haplorrhines developed more derived traits (became more different from ancestral primates).<\/p>\n<p class=\"import-Normal\">There are two other types of traits that will be relevant to our discussions here: generalized and specialized traits. <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1128\">Generalized traits<\/a> <\/strong>are those characteristics that are useful for a wide range of things. Having <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1138\">opposable thumbs<\/a><\/strong> that go in a different direction than the rest of your fingers is a very useful, generalized trait. You can hold a pen, grab a branch, peel a banana, or text your friends all thanks to your opposable thumbs! <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1130\">Specialized traits<\/a> <\/strong>are those that have been modified for a specific purpose. These traits may not have a wide range of uses, but they will be very efficient at their job. Hooves in horses are a good example of a specialized trait: they allow horses to run quickly on the ground on all fours. You can think of generalized traits as a Swiss Army knife, useful for a wide range of tasks but not particularly good at any one of them. That is, if you\u2019re in a bind, then a Swiss Army knife can be very useful to cut a rope or fix a loose screw, but if you were going to build furniture or fix a kitchen sink, then you\u2019d want specialized tools for the job. As we will see, most primate traits tend to be generalized.<\/p>\n<h2 class=\"import-Normal\">What Makes Something a Primate?<\/h2>\n<p class=\"import-Normal\">The Order Primates is distinguished from other groups of mammals in having a <em>suite of characteristics<\/em>. This means that there is no individual trait that you can use to instantly identify an animal as a primate; instead, you have to look for animals that possess a collection of traits. What this also means is that each individual trait we discuss may be found in nonprimates, but if you see an animal that has most or all of these traits, there is a good chance it is a primate.<\/p>\n<p class=\"import-Normal\">Primates are most distinguishable from other organisms in traits related to our vision. Our Order relies on vision as a primary sense, which is reflected in many areas of our anatomy and behaviour. All primates have eyes that face forward with convergent (overlapping) visual fields. So if you cover one eye with your hand, you can still see most of the room with your other one. This also means that we cannot see on the sides or behind us as well as some other animals can. In order to protect the sides of the eyes from the muscles we use for chewing, all primates have at least a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1132\">postorbital bar<\/a>, <\/strong>a bony ring around the outside of the eye (Figure 6.2). Primate taxa with more convergent eyes need extra protection, so animals with greater orbital convergence will have a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1134\">postorbital plate<\/a> <\/strong>or<strong> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1136\">postorbital closure<\/a> <\/strong>in addition to the bar (Figure 6.2).The postorbital bar is a derived trait of primates, appearing in our earliest ancestors.<\/p>\n<figure style=\"width: 661px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image2-4.jpg\" alt=\"Skulls of a monkey and lemur viewed from the side and top.\" width=\"661\" height=\"430\" \/><figcaption class=\"wp-caption-text\">Figure 6.2: All primates have bony protection around their eyes. Some have a postorbital bar only (right), but many have full postorbital closure, also called a postorbital plate, that completely protects the back of the eye socket (left). Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\" target=\"_blank\">Postorbital bar\/Postorbital closure (Figure 5.1)<\/a> a derivative work original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\" target=\"_blank\">CC BY-NC-SA 4.0 License<\/a>. [Includes <a href=\"https:\/\/animaldiversity.org\/accounts\/Otolemur_crassicaudatus\/specimens\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Otolemur_crassicaudatus\/lateral\/\" target=\"_blank\">Otolemur crassicaudatus (greater galago)<\/a> by <a href=\"https:\/\/animaldiversity.org\/\" target=\"_blank\">Animal Diversity Web<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\" target=\"_blank\">CC BY-NC-SA 3.0<\/a>; <a href=\"https:\/\/animaldiversity.org\/accounts\/Otolemur_crassicaudatus\/specimens\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Otolemur_crassicaudatus\/dorsal1809\/\" target=\"_blank\">Macaca fascicularis (long-tailed macaque)<\/a> by <a href=\"https:\/\/animaldiversity.org\/\" target=\"_blank\">Animal Diversity Web<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\" target=\"_blank\">CC BY-NC-SA 3.0<\/a>.]<\/figcaption><\/figure>\n<p class=\"import-Normal\">Another distinctive trait of our Order is that many primates have <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1140\">trichromatic color vision<\/a><\/strong>, the ability to distinguish reds and yellows in addition to blues and greens. Birds, fish, and reptiles are <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1142\">tetrachromatic<\/a> <\/strong>(they can see reds, yellows, blues, greens, and even ultraviolet), but most mammals, including some primates, are only <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1144\">dichromatic<\/a> <\/strong>(they see only in blues and greens). It is thought that the nocturnal ancestors of mammals benefited from seeing better at night rather than in colour, and so dichromacy is the ancestral condition for mammals. Trichromatic primates are known to use their colour vision for all sorts of purposes: finding young leaves and ripe fruits, identifying other species, and evaluating signals of health and fertility.<\/p>\n<p class=\"import-Normal\">The primate visual system uses a lot of energy, so primates have compensated by cutting back on other sensory systems, particularly our sense of smell. Compared to other mammals, primates have reduced snouts, another derived trait that appears even in the earliest primate ancestors. There is variation across primate taxa in how much snouts are reduced. Those with a better sense of smell usually have poorer vision than those with a relatively dull sense of smell. The reason for this is that all organisms have a limited amount of energy to spend on running our bodies, so we make <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1146\">evolutionary trade-offs<\/a><\/strong>, as energy spent on one trait cuts back on energy spent on another. So primates with better vision are spending more energy on vision and thus have a poorer smell (and shorter snout), and those who spend less energy on vision will have a better sense of smell (and a longer snout).<\/p>\n<p class=\"import-Normal\">Primates also differ from other mammals in the size and complexity of our brains. On average, primates have brains that are twice as big for their body size when compared to other mammals. Not unexpectedly, the visual centres of the brain are larger in primates and the wiring is different from that in other animals, reflecting our reliance on this sense. The neocortex, which is used for higher functions like consciousness and language in humans, as well as sensory perception and spatial awareness, is also larger in primates relative to other animals. In nonprimates this part of the brain is often smooth, but in primates it is made up of many folds, which increase the surface area. It has been proposed that the more complex neocortex of primates is related to diet, with fruit-eating primates having larger relative brain sizes than leaf-eating primates, due to the more challenging cognitive demands required to find and process fruits (Clutton-Brock &amp; Harvey 1980). An alternative hypothesis argues that larger brain size is necessary for navigating the complexities of primate social life, with larger brains occurring in species who live in bigger, more complex groups relative to those living in pairs or solitarily (Dunbar 1998). There seems to be support for both hypotheses, as large brains are a benefit under both sets of selective pressures.<\/p>\n<p class=\"import-Normal\">Animals with large brains usually have extended life history patterns, and primates are no exception. <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1148\">Life history<\/a> <\/strong>refers to the pace at which an organism grows, reproduces, and ages. Some animals grow very quickly and reproduce many offspring in a short time frame but do not live very long. Other animals grow slowly, reproduce few offspring, reproduce infrequently, and live a long time. Primates are all in the \u201cslow lane\u201d of life history patterns. Compared to animals of similar body size, primates grow and develop more slowly, have fewer offspring per pregnancy, reproduce less often, and live longer. Primates also invest heavily in each offspring. With a few exceptions, most primates only have one offspring at a time. A group of small-bodied monkeys in South America regularly give birth to twins, and some lemurs can give birth to multiple offspring at a time, but these primates are the exception rather than the rule. Primates also reproduce relatively infrequently. The fastest-reproducing primates will produce offspring about every six months, while the slowest, the orangutan, reproduces only once every seven to nine years. This very slow reproductive rate makes the orangutan the slowest-reproducing animal on the planet! Primates are also characterized by having long lifespans. The group that includes humans and large-bodied apes has the most extended life history patterns among all primates, with some large-bodied apes estimated to live up to 58 years in the wild (Robson Et al. 2006).<\/p>\n<figure style=\"width: 392px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image3-5.jpg\" alt=\"Various hands and feet of different primate species.\" width=\"392\" height=\"624\" \/><figcaption class=\"wp-caption-text\">Figure 6.3: These drawings of the hands and feet of different primates show the opposable thumbs and big toes, pentadactyly, flattened nails, and tactile pads characteristic of our Order. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:PrimateFeet.jpg\" target=\"_blank\">PrimateFeet<\/a> by <a href=\"https:\/\/en.wikipedia.org\/wiki\/Richard_Lydekker\" target=\"_blank\">Richard Lydekker<\/a>, original from The Royal Natural History 1:15 (1893), is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\" target=\"_blank\">public domain<\/a>.<\/figcaption><\/figure>\n<p>Primates also differ from other animals in our hands and feet. The Order Primates is a largely <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1150\">arboreal<\/a><\/strong> taxonomic group, meaning that most primates spend a significant amount of their time in trees. As a result, the hands and feet of primates have evolved to move in a three-dimensional environment. Primates have the generalized trait of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1152\">pentadactyly<\/a><\/strong>\u2014 possessing five digits (fingers and toes) on each limb. Many nonprimates, like dogs and horses, have fewer digits because they are specialized for high-speed, <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1154\">terrestrial<\/a><\/strong> (on the ground) running. Pentadactyly is also an ancestral trait, one that dates back to the earliest four-footed animals. Primates today have opposable thumbs and, with the exception of humans, opposable big toes (Figure 6.3). Opposable thumbs and toes are a derived trait that appeared in the earliest primate fossils about 55 million years ago. Having thumbs and big toes that go in a different direction from the rest of the fingers and toes allow primates to be excellent climbers in trees as well as to manipulate objects. Our ability to manipulate objects is further enhanced by the flattened nails on the backs of our fingers and toes that we possess in the place of the claws and hooves that many other mammals have. On the other side of our digits, we have sensitive <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1156\">tactile pads<\/a> <\/strong>that allow us to have a fine sense of touch. Primates use this fine sense of touch for handling food and, in many species, grooming themselves and others. In primates, grooming is an important social currency, through which individuals forge and maintain social bonds.<\/p>\n<table class=\"alignright\" style=\"width: 219.75pt;height: 407px\">\n<caption>Figure 6.4: Primate Traits at a Glance: This table summarizes the suite of traits that differentiate primates from other mammals. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\" target=\"_blank\">Primate at a glance table (Figure 5.3)<\/a> by Stephanie Etting original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/caption>\n<thead>\n<tr style=\"height: 30px\">\n<td class=\"a-C\" style=\"background-color: transparent;padding: 5pt;border: 1pt solid #000000;height: 30px;width: 361.667px\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Primate suite of traits<\/strong><\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"a-R\" style=\"height: 362px\">\n<td class=\"a-C\" style=\"background-color: transparent;padding: 5pt;border: 1pt solid #000000;height: 362px;width: 361.667px\">\n<p class=\"import-Normal\" style=\"text-align: center\">Convergent eyes<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Postorbital bar<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Many have trichromatic colour vision<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Short snouts<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Opposable thumbs and big toes<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Pentadactyly<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Flattened nails<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Tactile pads<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Highly arboreal<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Large brains<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Extended life histories<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Live in the tropics<\/p>\n<\/td>\n<\/tr>\n<tr style=\"height: 15px\">\n<td style=\"height: 15px;width: 362.033px\"><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>Lastly, primates are very social animals. All primates, even those that search for food alone, establish strong social networks within species. Unlike many animals, primates do not migrate: they stay in a relatively stable area for their whole life, often interacting with the same individuals for their long lives. The long-term relationships that primates form with others of their species lead to complex and fascinating social behaviours (see Chapter 7). Finally, nonhuman primates show a clear preference for tropical regions of the world. Most primates are found between the Tropic of Cancer and the Tropic of Capricorn, with only a few taxa living outside these regions. Figure 6.4 shows a summary of primate traits.<\/p>\n<h2 class=\"import-Normal\">Key Traits Used to Distinguish Between Primate Taxa<\/h2>\n<p class=\"import-Normal\">When placing primate species into specific taxonomic groups, we focus on dental characteristics, behavioural adaptations, and locomotor adaptations. Differences in these characteristics across groups reflect constraints of evolutionary history as well as variation in adaptations.<\/p>\n<h3 class=\"import-Normal\"><strong>Dental Characteristics<\/strong><\/h3>\n<p class=\"import-Normal\">Teeth may not seem like the most exciting topic with which to start, but we can learn a tremendous amount about an organism from its teeth. First, teeth are vital to survival. Wild animals do not have the benefit of knives and forks; they rely on their teeth to process their food. Because of this, teeth of any species have evolved to reflect what that organism eats and therefore have a lot to tell us about their diet. Second, variation in tooth size, shape, and number reveals an organism\u2019s evolutionary history. Some taxa have more teeth than others or different forms of teeth. Furthermore, differences in teeth between males and females can tell us about competition over mates (see Chapter 7). Lastly, teeth are overly represented in the fossil record. Enamel is hard, and there is little meat on jaws so carnivores and scavengers often leave them behind. Sometimes, the only remains we have from an extinct taxon is its teeth!<\/p>\n<figure style=\"width: 356px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image4-4-1.jpg\" alt=\"Yawning baboon with large teeth.\" width=\"356\" height=\"266\" \/><figcaption class=\"wp-caption-text\">Figure 6.5: This picture of an open-mouthed Hamadryas baboon demonstrates the diastema between his upper canine and front teeth. This space is taken up by his lower canine when he closes his mouth. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Ha,ha,ha_...._(14986571843).jpg\" target=\"_blank\">Ha,ha,ha .... (14986571843)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/104249543@N07\" target=\"_blank\">Rolf Dietrich Brecher<\/a> from Germany is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\" target=\"_blank\">CC BY-SA 2.0 License<\/a>.<\/figcaption><\/figure>\n<p>Like other mammals, primates are <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1158\">heterodont<\/a><\/strong>: they have multiple types of teeth that are used for different purposes. We have <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1160\">incisors<\/a> <\/strong>for slicing; <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1162\">premolars<\/a> <\/strong>and <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1164\">molars<\/a> <\/strong>for grinding up our food; and <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1166\">canines<\/a><\/strong>, which most primates (not humans) use as weapons against predators and each other. The sizes of canines vary across species and can often be <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1168\">sexually dimorphic<\/a><\/strong>, with males tending to have larger canines than females. Some nonhuman primates <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1170\">hone<\/a><\/strong>, or sharpen, their canines by gnashing the teeth together to sharpen the sides. The upper canine sharpens on the first lower premolar and the lower canine sharpens on the front of the upper canine. As canines get larger, they require a space to fit in order for the jaws to close. This space between the teeth is called a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1172\">diastema<\/a><\/strong> (Figure 6.5).<\/p>\n<p class=\"import-Normal\">We use a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1174\">dental formula<\/a><\/strong> to specify how many incisors, canines, premolars, and molars are in each quadrant of the mouth (half of the top or bottom). For example, Figure 6.6 shows half of the lower teeth of a human. You can see that in half of the mandible, there are two incisors, one canine, two premolars, and three molars. This dental formula is written as 2:1:2:3. (The first number represents the number of incisors, followed by the number of canines, premolars, and molars.)<\/p>\n<figure style=\"width: 241px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image5-5.png\" alt=\"Human mandible with four types of teeth.\" width=\"241\" height=\"424\" \/><figcaption class=\"wp-caption-text\">Figure 6.6:\u00a0 This drawing shows half of the human mandible. With the four types of teeth labeled, you can determine that the dental formula is 2:1:2:3. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Gray997.png\" target=\"_blank\">Gray997<\/a> by <a href=\"https:\/\/en.wikipedia.org\/wiki\/Henry_Vandyke_Carter\" target=\"_blank\">Henry Vandyke Carter<\/a>, original in Henry Gray (1918) Anatomy of the Human Body, Plate 997, is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\" target=\"_blank\">public domain<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">To determine the dental formula, you need to be able to identify the different types of teeth. You can recognize incisors because they often look like spatulas with a flat, blade-like surface. Premolars and molars can be differentiated by the number of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1176\">cusps<\/a><\/strong> that they have. Cusps are the bumps that you can feel with your tongue on the surface of your back teeth. Premolars are smaller than molars and, in primates, often have one or two cusps on them. Molars are bigger, providing a larger chewing surface, and have more cusps. Depending on the species and whether you\u2019re looking at upper or lower teeth, primate molars can have between three and five cusps. Molar cusps can also vary between taxa in how they are arranged; you will learn more about this later in this chapter. Canines are often easy to distinguish because, in most taxa, they are much longer and more conical than the other teeth.<\/p>\n<p class=\"import-Normal\">Teeth also directly reflect an organism\u2019s diet. Primates are known to eat a wide range of plant parts, insects, gums, and, rarely, meat. While all primates eat a variety of foods, what differs among primates are the proportions of each of these food items in the diet. That is, two primates living in the same forest may be eating the same foods but in vastly different proportions, and so we would categorize them as different dietary types. The most common dietary types among primates are those whose diets consist primarily of fruit (<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_954\">frugivores<\/a><\/strong>), those who eat mostly insects (<strong>insectivores<\/strong>), and those who eat primarily leaves (<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_956\">folivores<\/a><\/strong>). A few primate taxa are <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1178\">gummivores<\/a><\/strong>, specializing in eating gums and saps, but we will only focus on the adaptations found in the three primary dietary groups.<\/p>\n<h4 class=\"import-Normal\"><em>Frugivores<\/em><\/h4>\n<p class=\"import-Normal\">Plants want animals to eat their fruits because, in doing so, animals eat the seeds of the fruit and then disperse them far away from the parent plant. Therefore, plants often \u201cadvertise\u201d fruits by making them colourful and easy to spot, full of easy-to-digest sugars that make them taste good and, often, easy to chew and digest (not being too fibrous or tough). For these reasons, frugivores often do not need a lot of specialized traits to consume a diet rich in fruits (Figure 6.7). Their molars usually have a broad chewing surface with low, rounded cusps (referred to as <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1180\">bunodont<\/a> <\/strong>molars). Frugivores have large incisors for slicing through the outer coatings on fruit, and they tend to have stomachs, colons, and small intestines that are intermediate in terms of size and complexity between insectivores and folivores (Chivers &amp; Hladik 1980). They are also usually of intermediate body size between the other two dietary types. Because fruit does not contain protein, frugivores must supplement their diet with protein from insects, leaves, and\/or seeds. Frugivores who get protein by eating seeds evolved to have thicker enamel on their teeth to protect them from excessive wear.<\/p>\n<figure style=\"width: 503px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image6-2.jpg\" alt=\"Upper teeth and maxilla of a frugivore monkey.\" width=\"503\" height=\"331\" \/><figcaption class=\"wp-caption-text\">Figure 6.7: Frugivores are characterized by large incisors, bunodont molars, and digestive tracts that are intermediate in complexity between the other two dietary types. Credit: <a href=\"https:\/\/animaldiversity.org\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Papio_papio\/utr0087\/\" target=\"_blank\">Papio papio (Guinea baboon).jpg<\/a> by Phil Myers on <a href=\"https:\/\/animaldiversity.org\" target=\"_blank\">Animal Diversity Web<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\" target=\"_blank\">CC BY-NC-SA 3.0 License. <\/a><\/figcaption><\/figure>\n<h4 class=\"import-Normal\"><em>Insectivores<\/em><\/h4>\n<p class=\"import-Normal\">While insects can be difficult to find and catch, they are easy to chew and digest. As a result, insectivorous primates usually have small molars with pointed cusps to puncture the exoskeleton of the insects (Figure 6.8), and they have simple stomachs and colons with a long small intestine to process the insects. Nutritionally, insects provide a lot of protein and fat but are not plentiful enough in the environment to support large-bodied animals, so insectivores are usually the smallest of the primates.<\/p>\n<figure style=\"width: 351px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image7-3.jpg\" alt=\"Mandible, upper teeth, and maxilla of insectivore tarsier.\" width=\"351\" height=\"280\" \/><figcaption class=\"wp-caption-text\">Figure 6.8: Insectivores need sharp, pointed molar cusps to break through the exoskeletons of insects. Insects are easy to digest, so these primates have simple digestive tracts. Credit: Tarsier (an insectivor)\u2019s teeth original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Stephanie Etting is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\" target=\"_blank\">CC BY-NC-SA 3.0 License.<\/a> [Includes <a href=\"https:\/\/animaldiversity.org\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Tarsius_syrichta\/lower_lateral1942\/\" target=\"_blank\">Lower_lateral1942<\/a> by Phil Myers on <a href=\"https:\/\/animaldiversity.org\" target=\"_blank\">Animal Diversity Web<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\" target=\"_blank\">CC BY-NC-SA 3.0<\/a>; <a href=\"https:\/\/animaldiversity.org\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Tarsius_syrichta\/ventral\/\" target=\"_blank\">Ventral<\/a> by Phil Myers on <a href=\"https:\/\/animaldiversity.org\" target=\"_blank\">Animal Diversity Web<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\" target=\"_blank\">CC BY-NC-SA 3.0<\/a>.]<\/figcaption><\/figure>\n<h4 class=\"import-Normal\"><em>Folivores<\/em><\/h4>\n<p class=\"import-Normal\">Plants rely on leaves to get energy from the sun, so plants do not want animals to eat their leaves (unlike their fruit). As a result, plants evolved to try to discourage animals from eating their leaves. Leaves often carry toxins, taste bitter, are very fibrous and difficult to chew, and are made of large cellulose molecules that are difficult to break down into usable sugars. Thus, animals who eat leaves need a lot of specialized traits (Figure 6.9). Folivorous primates have broad molars with high, sharp cusps connected by <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1182\">shearing crests<\/a><\/strong>. These molar traits allow folivores to physically break down fibrous leaves when chewing. Folivores then chemically break down cellulose molecules into usable energy. To do this, some folivores have complex stomachs with multiple compartments, while others have large, long intestines and special gut bacteria that can break up cellulose. Folivores are usually the largest bodied of all primates, and they tend to spend a large portion of their day digesting their food, so they are less active than frugivores or insectivores.<\/p>\n<figure style=\"width: 468px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image8-2.jpg\" alt=\"Upper teeth and maxilla of a monkey shows folivore traits.\" width=\"468\" height=\"337\" \/><figcaption class=\"wp-caption-text\">Figure 6.9: To derive energy from leaves, folivores, like this Trachypithecus (dusky leaf monkey), have smaller incisors and high sharp molar cusps connected by shearing crests. Credit: <a href=\"https:\/\/animaldiversity.org\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Trachypithecus_obscurus\/utr0075\/\" target=\"_blank\">Trachypithecus obscurus (dusky leaf monkey) upper teeth<\/a> by Phil Myers on <a href=\"https:\/\/animaldiversity.org\" target=\"_blank\">Animal Diversity Web<\/a> has been modified (background removed, labels added by Stephanie Etting) is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\" target=\"_blank\">CC BY-NC-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<h3 class=\"import-Normal\"><strong>Behavioural Adaptations<\/strong><\/h3>\n<p class=\"import-Normal\">Since Chapter 6 is dedicated to primate behaviour, we will only briefly discuss variations in activity patterns, social grouping, and habitat use. Primate groups differ in <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1184\">activity patterns<\/a><\/strong>: whether they are active during the day (<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1012\">diurnal<\/a><\/strong>), at night (<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1010\">nocturnal<\/a><\/strong>), or through the 24-hour period (<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1186\">cathemeral<\/a><\/strong>). Primate taxa vary in social groupings: some are primarily solitary, others live in pairs, and still others live in groups of varying sizes and compositions. Lastly, some taxa are primarily arboreal while others are more terrestrial.<\/p>\n<h3 class=\"import-Normal\"><strong>Locomotor Adaptations<\/strong><\/h3>\n<p class=\"import-Normal\">Finally, primate groups vary in their adaptations for different forms of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1188\">locomotion<\/a><\/strong>, or how they move around. Living primates are known to move by vertical clinging and leaping, quadrupedalism, brachiation, and bipedalism.<\/p>\n<p class=\"import-Normal\"><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1190\">Vertical clinging and leaping<\/a> <\/strong>is when an animal grasps a vertical branch with its body upright, pushes off with long hind legs, and then lands on another vertical support branch (Figure 6.10a). Animals who move in this way usually have longer legs than arms, long fingers and toes, and smaller bodies. Vertical clinger leapers also tend to have elongated ankle bones, which serve as a lever to help them push off with their legs and leap to another branch (Figure 6.10b).<\/p>\n<figure id=\"attachment_181\" aria-describedby=\"caption-attachment-181\" style=\"width: 608px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-147\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/5.10.jpg\" alt=\"Movement of vertical clinger and leaper, and tarsier skeleton.\" width=\"608\" height=\"462\" \/><figcaption id=\"caption-attachment-181\" class=\"wp-caption-text\">Figure 6.10a: Vertical clingers and leapers have longer legs than arms, long lower backs, and long fingers and toes. They also have elongated ankle bones to help them push off when leaping. Credit: a. <a href=\"https:\/\/upload.wikimedia.org\/wikipedia\/commons\/6\/6e\/Propithecus_vertical_clinging_and_leaping.svg\" target=\"_blank\">Propithecus vertical clinging and leaping<\/a> by Terpsichores is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/\" target=\"_blank\"> CC BY-SA 3.0 License<\/a>. 6.10b: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Em_-_Tarsius_tarsier_-_3.jpg\" target=\"_blank\">Tarsier skeleton<\/a> by Em\u0151ke D\u00e9nes has been modified (background removed) by Stephanie Etting and is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/\" target=\"_blank\">CC BY-SA 4.0 License<\/a>. Original Spectral tarsier (Tarsius tarsier) skeleton at the Cambridge University Museum of Zoology, England.)<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<div class=\"learning-objectives\">\n<p class=\"import-Normal\"><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1192\">Quadrupedalism<\/a><\/strong>, walking on all fours, is the most common form of locomotion among primates. Quadrupedal animals usually have legs and arms that are about the same length and a tail for balance. Arboreal quadrupeds (Figure 6.11a) usually have shorter arms and legs and longer tails, while terrestrial quadrupeds (Figure 6.11b) have longer arms and legs and, often, shorter tails. These differences relate to the lower centre of gravity needed by arboreal quadrupeds for balance in trees and the longer tail required for better balance when moving along the tops of branches. Terrestrial quadrupeds have longer limbs to help them cover more distance more efficiently.<\/p>\n<\/div>\n<figure id=\"attachment_181-2\" aria-describedby=\"caption-attachment-181-2\" style=\"width: 704px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-148\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/5.11.jpg\" alt=\"Arboreal quadrupedal monkey and terrestrial quadrupedal monkey.\" width=\"704\" height=\"251\" \/><figcaption id=\"caption-attachment-181-2\" class=\"wp-caption-text\">Figure 6.11a\/b: Two examples of quadrupedal primates. The capuchin monkey skeleton on the left (a) is a typical arboreal quadruped with shorter arms and legs, longer fingers and toes, and a long tail. The baboon skeleton on the right (b) is a terrestrial quadruped with relatively long arms and legs, shorter fingers and toes, and a short tail. Credits: 6.11a. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Description_iconographique_compar%C3%A9e_du_squelette_et_du_syst%C3%A8me_dentaire_des_mammif%C3%A8res_r%C3%A9cents_et_fossiles_(Sapajus_apella).jpg\" target=\"_blank\">Capuchin monkey skeleton<\/a> by Henri-Marie Ducrotay de Blainville is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\" target=\"_blank\">public domain<\/a>. 6.11b. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Description_iconographique_compar%C3%A9e_du_squelette_et_du_syst%C3%A8me_dentaire_des_mammif%C3%A8res_r%C3%A9cents_et_fossiles_(Papio_ursinus).jpg\" target=\"_blank\">Baboon<\/a> by Henri-Marie Ducrotay de Blainville is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\" target=\"_blank\">public domain<\/a>.<\/figcaption><\/figure>\n<div class=\"learning-objectives\">\n<p class=\"import-Normal\">The third form of locomotion seen in primates is<strong> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1194\">brachiation<\/a><\/strong>, the way of moving you used if you played on \u201cmonkey bars\u201d as a child. Brachiation involves swinging below branches by the hands (Figure 6.12a). To be an efficient brachiator, a primate needs to have longer arms than legs, flexible shoulders and wrists, a short lower back, and no tail (Figure 6.12b). Some primates move via <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1196\">semi-brachiation<\/a><\/strong>, in which they swing below branches but do not have all of the same specializations as brachiators. Semi-brachiators have flexible shoulders, but their arms and legs are about the same length, which is useful because they are quadrupedal when on the ground. They also use long <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1198\">prehensile tails<\/a><\/strong> as a third limb when swinging (Figure 6.13). The underside of the tail has a tactile pad, resembling your fingerprints, for better grip.<\/p>\n<\/div>\n<figure id=\"attachment_181-3\" aria-describedby=\"caption-attachment-181-3\" style=\"width: 1600px\" class=\"wp-caption alignnone\"><img class=\"wp-image-149 size-full\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/5.12.jpg\" alt=\"Primate swinging through branches and gibbon skeleton.\" width=\"1600\" height=\"800\" \/><figcaption id=\"caption-attachment-181-3\" class=\"wp-caption-text\">Figure 6.12a. Example of brachiation. 6.12b. Skeleton of a typical brachiator, showing longer arms than legs, short back, and lack of a tail. Credit: a. <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\" target=\"_blank\">Brachiator (Figure 5.9b)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>. b. <a href=\"https:\/\/upload.wikimedia.org\/wikipedia\/commons\/a\/a3\/Giboia.jpg\" target=\"_blank\">Skeleton of Gibbon (Giboia) <\/a>by Joxerra Aihartza is under a <a href=\"https:\/\/artlibre.org\" target=\"_blank\">Free Art License<\/a>.<\/figcaption><\/figure>\n<div class=\"learning-objectives\">\n<figure style=\"width: 565px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image15-1.jpg\" alt=\"Spider monkey swinging below a rope.\" width=\"565\" height=\"377\" \/><figcaption class=\"wp-caption-text\">Figure 6.13. Spider monkeys are considered semi-brachiators, as they can swing below branches but use their tails as a third limb. On the ground they move via quadrupedal locomotion. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Ateles-fusciceps_54724770b.jpg\" target=\"_blank\">Ateles-fusciceps 54724770b<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:LeaMaimone\" target=\"_blank\">LeaMaimone<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.5\/legalcode\" target=\"_blank\">CC BY 2.5 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Lastly, humans move around on two feet, called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1200\">bipedalism<\/a><\/strong>. Some nonhuman primates will occasionally travel on two feet but do so awkwardly and never for long distances. Among mammals, only humans have evolved to walk with a striding gait on two legs as a primary form of locomotion.<\/p>\n<h2 class=\"import-Normal\">Primate Diversity<\/h2>\n<p class=\"import-Normal\">As we begin exploring the different taxa of primates, it is important to keep in mind the hierarchical nature of taxonomic classification and how this relates to the key characteristics that will be covered. Figure 6.14 summarizes the major taxonomic groups of primates that you will learn about here. If you locate humans on the chart, you can trace our classification and see all of the categories getting more inclusive as you work your way up to the Order Primates. This means that humans will have the key traits of each of those groups. It is a good idea to refer to the figure to orient yourself as we discuss each taxon.<\/p>\n<figure style=\"width: 2048px\" class=\"wp-caption alignnone\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image16-1.jpg\" alt=\"Taxonomic chart shows primate order, suborder, infraorder, superfamily, and species.\" width=\"2048\" height=\"1154\" \/><figcaption class=\"wp-caption-text\">Figure 6.14: This taxonomy chart shows the major groups of primate taxa, starting with the largest category (Order) and moving to more specific categories and examples. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\">A full text description of this image is available<\/a>. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\" target=\"_blank\">Primate taxonomy char (Figure 5.11)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>. [Includes <a href=\"https:\/\/phylopic.org\/image\/d6cfb28f-136e-4a20-a5ac-8eb353c7fc4a\/\" target=\"_blank\">Lemur catta Linnaeus, 1759<\/a> by Roberto D\u00edaz Sibaja, <a href=\"https:\/\/creativecommons.org\/licenses\/by\/3.0\/\" target=\"_blank\">CC BY 3.0<\/a>; <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\" target=\"_blank\">Lorisoidea<\/a> original to<a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\"> Explorations: An Open Invitation to Biological Anthropology<\/a> by Katie Nelson, <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0<\/a>; <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\" target=\"_blank\">Tarsiiformes<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson, <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0<\/a>; <a href=\"https:\/\/phylopic.org\/image\/156b515d-f25c-4497-b15b-5afb832cc70c\/\" target=\"_blank\">Cebinae Bonaparte, 1831<\/a> by Sarah Werning, <a href=\"https:\/\/creativecommons.org\/licenses\/by\/3.0\/\" target=\"_blank\">CC BY 3.0<\/a>; <a href=\"https:\/\/phylopic.org\/image\/899742c2-9a40-4fa0-b2cd-2eb133c8f6e8\/\" target=\"_blank\">Colobus guereza Ruppell, 1835<\/a> by Yan Wong, designated to the <a href=\"https:\/\/creativecommons.org\/publicdomain\/zero\/1.0\/\" target=\"_blank\">public domain (CC0)<\/a>; <a href=\"https:\/\/phylopic.org\/image\/72f2f854-f3cd-4666-887c-35d5c256ab0f\/\" target=\"_blank\">Papio cynocephalus<\/a> by Owen Jones, designated to the <a href=\"https:\/\/creativecommons.org\/publicdomain\/zero\/1.0\/\" target=\"_blank\">public domain (CC0)<\/a>; <a href=\"https:\/\/pixabay.com\/vectors\/animals-silhouette-wolf-elephant-2755766\/\" target=\"_blank\">animals silhouette wolf elephant (2755766)<\/a> by <a href=\"https:\/\/pixabay.com\/users\/mohamed_hassan-5229782\/\" target=\"_blank\">mohamed_hassan<\/a>, <a href=\"https:\/\/pixabay.com\/service\/terms\/#license\" target=\"_blank\">Pixabay License<\/a>.]<\/figcaption><\/figure>\n<h3 class=\"import-Normal\"><strong>Suborder Strepsirrhini<\/strong><\/h3>\n<figure style=\"width: 387px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image17-1.jpg\" alt=\"Eight strepsirrhine species.\" width=\"387\" height=\"605\" \/><figcaption class=\"wp-caption-text\">Figure 6.15: (Clockwise from top right) sifaka, black-and-white ruffed lemur, loris, galago, slender loris, mouse lemur, aye-aye, and ring-tailed lemur. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Extant_Strepsirrhini.jpg\" target=\"_blank\">Extant Strepsirrhini<\/a> a collective work by <a href=\"https:\/\/www.flickr.com\/people\/23661161@N02\" target=\"_blank\">Mark Dumont<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0 License<\/a>. [Includes <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Katta_csal%C3%A1d.jpg\" target=\"_blank\">Katta csal\u00e1d<\/a> by Veszpr\u00e9mi \u00c1llatkert, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Aye-aye_at_night_in_the_wild_in_Madagascar.jpg\" target=\"_blank\">Aye-aye at night in the wild in Madagascar<\/a> by Frank Vassen, <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/deed.en\" target=\"_blank\">CC BY 2.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Diademed_ready_to_push_off.jpg\" target=\"_blank\">Diademed ready to push off<\/a> by Michael Hogan, designated to the <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/cc0\/\" target=\"_blank\">public domain (CC0)<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Juvenile_Black-and-White_Ruffed_Lemur,_Mantadia,_Madagascar.jpg\" target=\"_blank\">Juvenile Black-and-White Ruffed Lemur, Mantadia, Madagascar<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/42244964@N03\" target=\"_blank\">Frank Vassen<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/legalcode\" target=\"_blank\">CC BY 2.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Microcebus_murinus_-Artis_Zoo,_Amsterdam,_Netherlands-8a.jpg\" target=\"_blank\">Microcebus murinus -Artis Zoo, Amsterdam, Netherlands-8a<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/46956042@N00\" target=\"_blank\">Arjan Haverkamp<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/legalcode\" target=\"_blank\">CC BY 2.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Slow_Loris.jpg\" target=\"_blank\">Slow Loris<\/a> by Jmiksanek, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Slender_Loris.jpg\" target=\"_blank\">Slender Loris<\/a> by Kalyan Varma (<a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Kalyanvarma\" target=\"_blank\">Kalyanvarma<\/a>), <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\" target=\"_blank\">CC BY-SA 4.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Garnett&apos;s_Galago_(Greater_Bushbaby).jpg\" target=\"_blank\">Garnett's Galago (Greater Bushbaby)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/23661161@N02\" target=\"_blank\">Mark Dumont<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/legalcode\" target=\"_blank\">CC BY 2.0<\/a>.]<\/figcaption><\/figure>\n<p>The Order Primates is subdivided into Suborder Strepsirrhini and Suborder Haplorrhini, which, according to molecular estimates, split about 70\u201380 million years ago (Pozzi et al. 2014). The strepsirrhines include the groups commonly called lemurs, lorises, and galagos (Figure 6.15). Strepsirrhines differ from haplorrhines in many ways, most of which involve retaining ancestral traits from the earliest primates. Strepsirrhines do have two key derived traits that evolved after they diverged from the haplorrhines: the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1202\">grooming claw<\/a> <\/strong>(Figure 6.16) on the second digit of each foot, and the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1204\">tooth comb<\/a><\/strong> (or <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1206\">dental comb<\/a><\/strong>) located on the lower, front teeth (Figure 6.17). In most strepsirrhines, there are six teeth in the toothcomb\u2014four incisors and two canines. Other than the tooth comb, the teeth of strepsirrhines are fairly simple and are neither large or distinctive relative to haplorrhines.<\/p>\n<figure style=\"width: 237px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image18.jpg\" alt=\"A long, thin dark claw is visible in contrast to flat dark nails on the other digits.\" width=\"237\" height=\"202\" \/><figcaption class=\"wp-caption-text\">Figure 6.16: The foot of a ring-tailed lemur showing its grooming claw on the second digit. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Lemur_catta_toilet_claw.jpg\" target=\"_blank\">Lemur catta toilet claw<\/a> by Alex Dunkel (Maky) is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/3.0\/legalcode\" target=\"_blank\">CC BY 3.0 License.<\/a><\/figcaption><\/figure>\n<p class=\"import-Normal\">Compared to haplorrhines, strepsirrhines rely more on nonvisual senses. Strepsirrhines get their name because they have wet noses (<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1208\">rhinariums<\/a><\/strong>) like cats and dogs, a trait that, along with a longer snout, reflect strepsirrhines\u2019 greater reliance on olfaction relative to haplorrhines. Many strepsirrhines use <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1210\">scent marking<\/a><\/strong>, including rubbing scent glands or urine on objects in the environment to communicate with others. Additionally, many strepsirrhines have mobile ears that they use to locate insect prey and predators. While strepsirrhines have a better sense of smell than haplorrhines, their visual adaptations are more ancestral. Strepsirrhines have less convergent eyes than haplorrhines and therefore all have postorbital bars, whereas haplorrhines have full postorbital closure (see Figure 6.2). All strepsirrhines have a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1212\">tapetum lucidum<\/a><\/strong>, a reflective layer at the back of the eye that reflects light and thereby enhances the ability to see in low-light conditions. It is the same layer that causes your dog or cat to have \u201cyellow eye\u201d when you take photos of them with the flash on. This is a trait thought to be ancestral among mammals as a whole.<\/p>\n<figure style=\"width: 292px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image19-1.jpg\" alt=\"The lower, front teeth are long, thin, tightly together in a line, and project towards the lips.\" width=\"292\" height=\"354\" \/><figcaption class=\"wp-caption-text\">Figure 6.17: The lower front teeth of a ring-tailed lemur showing the six teeth of the tooth comb: four incisors and two canines. The teeth that superficially look like canines are premolars. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Lemur_catta_toothcomb.jpg\" target=\"_blank\">Lemur catta toothcomb<\/a> by Alex Dunkel (Maky) is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/3.0\/legalcode\" target=\"_blank\">CC BY 3.0 license.<\/a><\/figcaption><\/figure>\n<p class=\"import-Normal\">Strepsirrhines also differ from haplorrhines in some aspects of their ecology and behaviour. The majority of strepsirrhines are solitary, traveling alone to search for food; a few taxa are more social. Most strepsirrhines are also nocturnal and arboreal. Strepsirrhines are, on average, smaller than haplorrhines, and so many of them have a diet consisting of insects and fruit, with few taxa eating primarily leaves. Lastly, most strepsirrhines are good at leaping, with several taxa specialized for vertical clinging and leaping. In fact, among primates, all but one of the vertical clinger leapers belong to the Suborder Strepsirrhini.<\/p>\n<p class=\"import-Normal\">Strepsirrhines can be found all across Asia, Africa, and on the island of Madagascar (Figure 6.18). The Suborder Strepsirrhini is divided into two groups: (1) the lemurs of Madagascar and (2) the lorises, pottos, and galagos of Africa and Asia. By molecular estimates, these two groups split about 65 million years ago (Pozzi Et al. 2014).<\/p>\n<figure style=\"width: 443px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image20-1.png\" alt=\"Map strepsirrhine primates locations.\" width=\"443\" height=\"342\" \/><figcaption class=\"wp-caption-text\">Figure 6.18: Geographic distribution of living strepsirrhines. Lemurs live only on Madagascar, while lorises and galagos live across Central Africa and South and Southeast Asia. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\" target=\"_blank\">Geographic distribution of living strepsirrhines (Figure 5.16)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Elyssa Ebding at <a href=\"https:\/\/www.csuchico.edu\/geop\/geoplace\/index.shtml\" target=\"_blank\">GeoPlace, California State University, Chico<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<h4><em>Lemurs of Madagascar<\/em><\/h4>\n<p class=\"import-Normal\">Madagascar is an island off the east coast of Africa, and it is roughly the size of California, Oregon, and Washington combined. It has been separated from Africa for about 130 million years and from India for about 85 million years, which means it was already an island when strepsirrhines got there approximately 60\u201370 million years ago. Only a few mammal species ever reached Madagascar, and so when lemurs arrived they were able to flourish into a variety of forms.<\/p>\n<p class=\"import-Normal\">The lemurs of Madagascar are much more diverse compared to their mainland counterparts, the lorises and galagos. While many Malagasy strepsirrhines are nocturnal, plenty of others are diurnal or cathemeral. They range in body size from the smallest of all primates, the mouse lemur, some species of which weigh a little over an ounce (see Figure 6.15), up to the largest of all strepsirrhines, the indri, which weighs up to about 20 pounds (Figure 6.19). Lemurs include species that are insectivorous, frugivorous, and folivorous. A couple of members of this group have unusual diets for primates, including the gummivorous fork-marked and bamboo lemurs, who are able to metabolize the cyanide in bamboo. The most unique lemur is the aye-aye (depicted in Figure 6.15). This nocturnal lemur has rodent-like front teeth that grow continuously and a long-bony middle finger that it uses to fish grubs out of wood. It has a very large brain compared to other strepsirrhines, which it fuels with a diet that includes bird\u2019s eggs and other animal matter. Based on genetic estimates and morphological studies, it is believed that aye-ayes were the first lemurs to separate from all other strepsirrhines and to evolve on their own since strepsirrhines arrived in Madagascar (Matsui Et al. 2009).<\/p>\n<figure style=\"width: 326px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image21-1-1.jpg\" alt=\"Two Indis in a tree.\" width=\"326\" height=\"217\" \/><figcaption class=\"wp-caption-text\">Figure 6.19: Indris, the largest of the lemurs. These folivorous lemurs are vertical clingers and leapers and live in pairs. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Indri_indri_0003.jpg\" target=\"_blank\">Indri indri 0003<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Christophe_Germain\" target=\"_blank\">Christophe Germain<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\" target=\"_blank\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Lemurs are also diverse in terms of social behaviour: Many lemurs are solitary foragers, some live in pairs, others in small groups, still others in larger groups, and some, like the red-ruffed lemur, live in unique and complex social groups (Vasey 2006). Lemurs include some of the best vertical clingers and leapers, and while many lemurs are quadrupedal, even the quadrupedal lemurs are quite adept at leaping. Malagasy strepsirrhines also exhibit a few unusual traits. They are highly seasonal breeders, often mating only during a short window once a year (Wright 1999). Female ring-tailed lemurs, for example, come into estrus one day a year for a mere six hours. Unlike most primates, where males are typically large and dominant, Malagasy strepsirrhines feature socially dominant females that are similar in size to males and have priority access to resources.<\/p>\n<h4 class=\"import-Normal\"><em>Lorises, Pottos, and Galagos of Asia and Africa<\/em><\/h4>\n<figure style=\"width: 207px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image22-1.jpg\" alt=\"Slow loris hanging from a branch.\" width=\"207\" height=\"309\" \/><figcaption class=\"wp-caption-text\">Figure 6.20: This slow loris, like all others in this taxonomic group, is solitary and nocturnal, with a diet heavy in insects and fruit. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Nycticebus_coucang_002.jpg\" target=\"_blank\">Nycticebus coucang 002<\/a> by David Haring \/ Duke Lemur Center is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/deed.en\" target=\"_blank\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p>Unlike the lemurs of Madagascar, lorises, pottos, and galagos live in areas where they share their environments with monkeys and apes, who often eat similar foods. Lorises live across South and Southeast Asia, while pottos and galagos live across Central Africa. Because of competition with larger-bodied monkeys and apes, mainland strepsirrhines are more restricted in the niches they can fill in their environments and so are less diverse than the lemurs.<\/p>\n<p>The strepsirrhines of Africa and Asia are all nocturnal and solitary, with little variation in body size and diet. For the most part, the diet of lorises, pottos, and galagos consists of fruits and insects. A couple of species eat more gum, but overall the diet of this group is narrow when compared to the Malagasy lemurs. Lorises (Figure 6.20) and pottos are known for being slow, quadrupedal climbers, moving quietly through the forests to avoid being detected by predators. These strepsirrhines have developed additional defences against predators. Lorises, for example, eat a lot of caterpillars, which makes their saliva slightly toxic. Loris mothers bathe their young in this toxic saliva, making the babies unappealing to predators. In comparison to the slow-moving lorises and pottos, galagos are active quadrupedal runners and leapers that scurry about the forests at night. Galagos make distinctive calls that sound like a baby crying, which has led to their nickname \u201cbushbabies.\u201d Figure 6.21 summarizes the key differences between these two groups of strepsirrhines.<\/p>\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<caption>Figure 6.21: Strepsirrhini at a glance: This table summarizes the key differences between the two groups of strepsirrhines. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\" target=\"_blank\">Strepsirrhines at a glance table (Figure 5.19)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\" target=\"_blank\">CC BY-NC-SA 4.0 License<\/a>. [Includes <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Ringtailed_Lemurs_in_Berenty.jpg\" target=\"_blank\">Ringtailed Lemurs in Berenty<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/50852241@N00\" target=\"_blank\">David Dennis<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\" target=\"_blank\">CC BY-SA 2.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Komba_u%C5%A1at%C3%A1.jpg\" target=\"_blank\">Komba u\u0161at\u00e1<\/a> by Petr Hamern\u00edk, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\" target=\"_blank\">CC BY-SA 4.0<\/a>.]<\/caption>\n<thead>\n<tr>\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong><img class=\"alignnone\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image23-1.jpg\" alt=\"Baby primate on the back of adult primate.\" width=\"231\" height=\"165\" \/><\/strong><\/p>\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Lemurs<\/strong><\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong><img class=\"alignnone\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image24-1.jpg\" alt=\"Small primate with big eyes and long tail.\" width=\"198\" height=\"132\" \/><\/strong><\/p>\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Lorises, Pottos, and Galagos<\/strong><\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"a0-R\">\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Geographic range<\/strong><\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Madagascar<\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">South and Southeast Asia<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Central Africa<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a0-R\">\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Activity patterns<\/strong><\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Diurnal, nocturnal, or cathemeral<\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Nocturnal<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a0-R\">\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Dietary types<\/strong><\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Insectivore, frugivore, or folivore<\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Insectivore, frugivore<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a0-R\">\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Social groupings<\/strong><\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Solitary, pairs, or small to large groups<\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Solitary<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a0-R\">\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Forms of locomotion<\/strong><\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Vertical clinger leapers, quadrupedal<\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Slow quadrupedal climbers and active quadrupedal runners<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h3 class=\"import-Normal\"><strong>Suborder Haplorrhini<\/strong><\/h3>\n<p class=\"import-Normal\">When the two primate suborders split from one another, strepsirrhines retained more ancestral traits while haplorrhines developed more derived traits, which are discussed below.<\/p>\n<p class=\"import-Normal\">As mentioned earlier, haplorrhines have better vision than strepsirrhines. This is demonstrated by the full postorbital closure protecting the more convergent eyes that haplorrhines possess (with one exception seen in Figure 6.2). Most haplorrhines are trichromatic, and all have a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1410\">fovea<\/a><\/strong>, a depression in the retina at the back of the eye containing concentrations of cells that allows them to see things very close up in great detail. The heavier reliance on vision over olfaction is also reflected in the shorter snouts ending with the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1412\">dry nose<\/a> <\/strong>(no rhinarium) of haplorrhines. All but two genera of living haplorrhines are active during the day, so this group lacks the tapetum lucidum that is so useful to nocturnal species. On average, haplorrhines also have larger brains relative to their body size when compared with strepsirrhines.<\/p>\n<p class=\"import-Normal\">The Haplorrhini differ from the Strepsirrhini in their ecology and behaviour as well. Haplorrhines are generally larger than strepsirrhines, and they tend to be folivorous and frugivorous. This dietary difference is reflected in the teeth of haplorrhines, which are broader with more surface area for chewing. The larger body size of this taxon also influences locomotion. Only one haplorrhine is a vertical clinger and leaper. Most members of this suborder are quadrupedal, with one subgroup specialized for brachiation. A few haplorrhine taxa are <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1414\">monomorphic<\/a><\/strong>, meaning males and females are the same size, but many members of this group show moderate to high sexual dimorphism in body size and canine size. Haplorrhines also differ in social behaviour. All but two haplorrhines live in groups, which is very different from the primarily solitary strepsirrhines. Differences between the two suborders are summarized in Figure 6.22.<\/p>\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<caption>Figure 6.22: Suborders at a glance: This table summarizes the key differences between the two primate suborders. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\" target=\"_blank\">Suborders at a glance table (Figure 5.20)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\" target=\"_blank\">CC BY-NC-SA 4.0 License<\/a>. [Includes <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Black-and-White_Ruffed_Lemur,_Mantadia,_Madagascar.jpg\" target=\"_blank\">Black-and-White Ruffed Lemur, Mantadia, Madagascar<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/42244964@N03\" target=\"_blank\">Frank Vassen<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/legalcode\" target=\"_blank\">CC BY 2.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Crab_eating_macaque_face.jpg\" target=\"_blank\">Crab eating macaque face<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Bruce89\" target=\"_blank\">Bruce89<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\" target=\"_blank\">CC BY-SA 4.0<\/a>.]<\/caption>\n<thead>\n<tr>\n<td class=\"a1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong><img class=\"alignnone\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image25.jpg\" alt=\"Black-and-white ruffed lemur.\" width=\"213\" height=\"159\" \/><\/strong><strong>Suborder Strepsirrhini<\/strong><\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong><img class=\"alignnone\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image26-1.jpg\" alt=\"Crab-eating macaque.\" width=\"137\" height=\"137\" \/><\/strong><\/p>\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Suborder Haplorrhini<\/strong><\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"a1-R\">\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Sensory adaptations<\/strong><\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Rhinarium<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Longer snout<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Eyes less convergent<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Postorbital bar<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Tapetum lucidum<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Mobile ears<\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">No rhinarium<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Short snout<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Eyes more convergent<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Postorbital plate<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">No tapetum lucidum<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Many are trichromatic<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Fovea<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a1-R\">\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Dietary differences<\/strong><\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Mostly insectivores and frugivores, few folivores<\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Few insectivores, mostly frugivores and folivores<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a1-R\">\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Activity patterns and Ecology<\/strong><\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Mostly nocturnal, few diurnal or cathemeral<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Almost entirely arboreal<\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Only two are nocturnal, rest are diurnal<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Many arboreal taxa, also many terrestrial taxa<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a1-R\">\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Social groupings<\/strong><\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Mostly solitary, some pairs, small to large groups<\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Only two are solitary, all others live in pairs, small to very large groups<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a1-R\">\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Sexual dimorphism<\/strong><\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Minimal to none<\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Few taxa have little\/none, many taxa show moderate to high dimorphism<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p class=\"import-Normal\">Suborder Haplorrhini is divided into three infraorders: Tarsiiformes, which includes the tarsiers of Asia; Platyrrhini, which includes the monkeys of Central and South America; and Catarrhini, a group that includes the monkeys of Asia and Africa, apes, and humans. According to molecular estimates, tarsiers split from the other haplorrhines close to 70 million years ago, and platyrrhines split from catarrhines close to 46 million years ago (Pozzi Et al. 2014).<\/p>\n<h4 class=\"import-Normal\"><em>Infraorder Tarsiiformes of Asia<\/em><\/h4>\n<figure style=\"width: 188px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image27-1.jpg\" alt=\"Tarsier gripping a branch.\" width=\"188\" height=\"160\" \/><figcaption class=\"wp-caption-text\">Figure 6.23: Tarsiers are the only living representatives of this Infraorder. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Tarsier_Sanctuary,_Corella,_Bohol_(2052878890).jpg\" target=\"_blank\">Tarsier Sanctuary, Corella, Bohol (2052878890)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/46274125@N00\" target=\"_blank\">yeowatzup<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/legalcode\" target=\"_blank\">CC BY 2.0 License<\/a>.<\/figcaption><\/figure>\n<figure style=\"width: 362px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image28-1.png\" alt=\"Map of Southeast Asia shows distribution of tarsiers.\" width=\"362\" height=\"279\" \/><figcaption class=\"wp-caption-text\">Figure 6.24: Tarsiiformes are found in the tropical forests of multiple islands in Southeast Asia including Sumatra, Borneo, Celebes, and the Philippines. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\" target=\"_blank\">Infraorder Tarsiiformes of Asia map (Figure 5.22)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Elyssa Ebding at <a href=\"https:\/\/www.csuchico.edu\/geop\/geoplace\/index.shtml\" target=\"_blank\">GeoPlace, California State University, Chico<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p>Today, the Infraorder Tarsiiformes includes only one genus, <em>Tarsius <\/em>(Figure 6.23). Tarsiers are small-bodied primates that live in Southeast Asian forests (Figure 6.24) and possess an unusual collection of traits that have led to some debate about their position in the primate taxonomy. They are widely considered members of the haplorrhine group because they share several derived traits with monkeys, apes, and humans, including dry noses, a fovea, not having a tapetum lucidum, and eyes that are more convergent. Tarsiers also have some traits that are more like strepsirrhines and some that are unique. Tarsiers are the only haplorrhine that are specialized vertical clinger leapers, a form of locomotion only otherwise seen in some strepsirrhines. Tarsiers actually get their name because their ankle (tarsal) bones are elongated to provide a lever for vertical clinging and leaping. Tarsiiformes are also small, with most species weighing between 100 and 150 grams. Like strepsirrhines, tarsiers are nocturnal, but because they lack a tapetum lucidum, tarsiers compensate by having enormous eyes. In fact, each eye of a tarsier is larger than its brain. These large eyes allow enough light in for tarsiers to still be able to see well at night without the reflecting layer in their eyes. To protect their large eyes, tarsiers have a partially closed postorbital plate that appears somewhat intermediate between the postorbital bar of strepsirrhines and the full postorbital closure of other haplorrhines (Figure 6.25). Tarsiers have different dental formulas on their upper and lower teeth. On the top, the dental formula is 2:1:3:3, but on the bottom it is 1:1:3:3. Other unusual traits of tarsiers include having two grooming claws on each foot and the ability to rotate their heads around 180 degrees, a trait useful in locating insect prey. The tarsier diet is considered <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1416\">faunivorous<\/a> <\/strong>because it consists entirely of animal matter, making them the only primate not to eat any vegetation. They are only one of two living haplorrhines to be solitary, the other being the orangutan. Most tarsiers are not sexually dimorphic, like strepsirrhines, although males of a few species are slightly larger than females.<\/p>\n<figure style=\"width: 486px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image29-1.jpg\" alt=\"Front view of tarsier skull.\" width=\"486\" height=\"323\" \/><figcaption class=\"wp-caption-text\">Figure 6.25: Skull of a tarsier showing very large eye sockets and partially closed postorbital plates. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Tarsier_skull.jpg\" target=\"_blank\">Tarsier skull<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/65438265@N00\" target=\"_blank\">Andrew Bardwell<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\" target=\"_blank\">CC BY-SA 2.0 License.<\/a><\/figcaption><\/figure>\n<p class=\"import-Normal\">Two alternative classifications have emerged due to the unusual mix of traits that tarsiers have. Historically, tarsiers were grouped with lemurs, lorises, and galagos into a suborder called Prosimii. This classification was based on tarsiers, lemurs, lorises, and galagos all having grooming claws and similar lifestyles. Monkeys, apes, and humans were then separated into a suborder called the Anthropoidea. These suborder groupings were based on <em>grade<\/em> rather than <em>clade<\/em>. Today, most people use Suborders Strepsirrhini and Haplorrhini, which are clade groupings based on the derived traits that tarsiers share with monkeys, apes, and humans. The Strepsirrhini\/Haplorrhini dichotomy is also supported by the genetic evidence that indicates tarsiers are more closely related to monkeys, apes, and humans (Jameson Et al. 2011). Figure 6.26 summarizes the unusual mix of traits seen in tarsiers.<\/p>\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<caption>Figure 6.26: Tarsiers at a glance: Tarsiers have a mix of traits that lead to debate about their classification. While they have some unique characteristics, they also have traits that superficially resemble strepsirrhines, and many derived traits shared with haplorrhines. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\" target=\"_blank\">Tarsiers at a glance table (Figure 5.24)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/caption>\n<thead>\n<tr>\n<td class=\"a2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Like Strepsirrhini<\/strong><\/p>\n<\/td>\n<td class=\"a2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Unique<\/strong><\/p>\n<\/td>\n<td class=\"a2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Like Haplorrhini<\/strong><\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"a2-R\">\n<td class=\"a2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Very small<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Nocturnal<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Highly insectivorous<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Solitary<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Vertical clinger-leapers<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Little\/no sexual dimorphism<\/p>\n<\/td>\n<td class=\"a2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Two grooming claws<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">2:1:3:3\/1:1:3:3 dental formula<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Do not eat vegetation<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Can rotate their heads nearly 180 degrees<\/p>\n<\/td>\n<td class=\"a2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Almost full PO closure<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">More convergent eyes<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">No tapetum lucidum<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">No rhinarium<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Genetic evidence<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Fovea<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h4 class=\"import-Normal\"><em>Infraorder Platyrrhini of Central and South America<\/em><\/h4>\n<figure id=\"attachment_179\" aria-describedby=\"caption-attachment-179\" style=\"width: 329px\" class=\"wp-caption alignleft\"><img class=\"wp-image-165\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image30-e1686352290168.png\" alt=\"Map of South America shows where platyrrhines live.\" width=\"329\" height=\"324\" \/><figcaption id=\"caption-attachment-179\" class=\"wp-caption-text\">Figure 6.27: Geographic distribution of the platyrrhines across the southern part of Central America and the tropical and termporate regions of South America. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/ target=\">Infraorder Platyrrhini map<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Elyssa Ebding at <a href=\"https:\/\/www.csuchico.edu\/geop\/geoplace\/index.shtml\" target=\"_blank\">GeoPlace, California State University, Chico<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p>The platyrrhines are the only nonhuman primates in Central and South America (Figure 6.27) and so, like the lemurs of Madagascar, have diversified into a variety of forms in the absence of competition. Infraorder Platyrrhini get their name from their distinctive nose shape. \u201cPlaty\u201d means flat and \u201crhini\u201d refers to noses, and, indeed, platyrrhines have noses that are flat and wide, with nostrils that are far apart, facing outward, and usually round in shape (Figure 6.28). This nose shape is very different from what we see in catarrhines.<\/p>\n<p>On average, platyrrhines are smaller and less sexually dimorphic than catarrhines, and they have retained the more ancestral primate dental formula of 2:1:3:3. Platyrrhines are all highly arboreal, whereas many catarrhines spend significant time on the ground. The monkeys in Central and South America also differ in having less well-developed vision. This is reflected in the wiring in the visual system of the brain as well as in their <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1418\">polymorphic color vision<\/a><\/strong>. The genes that enable individuals to distinguish reds and yellows from blues and greens are on the X chromosome. Different genes code for being able to see different wavelengths of light so to distinguish between them you need to be heterozygous for seeing colour. The X chromosomes of platyrrhines each carry the genes for seeing one wavelength, so male platyrrhines (with only one X chromosome) are always dichromatic. Female platyrrhines can be dichromatic (if they are homozygous for one version of the colour vision gene) or trichromatic (if they are heterozygous) (Kawamura Et al. 2012). We currently know of two exceptions to this pattern among platyrrhines. Nocturnal owl monkeys are <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1420\">monochromatic<\/a><\/strong>, meaning that they cannot distinguish any colours. The other exception are howler monkeys, which have evolved to have two colour vision genes on each X chromosome. This means that both male and female howler monkeys are able to see reds and yellows. By contrast, catarrhine males and females are all trichromatic.<\/p>\n<figure style=\"width: 279px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image31-1.jpg\" alt=\"White-faced capuchin monkey.\" width=\"279\" height=\"190\" \/><figcaption class=\"wp-caption-text\">Figure 6.28: A capuchin monkey demonstrating a typical platyrrhine nose shape with round nostrils pointing outward on a flat nose. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:CARABLANCA_-_panoramio.jpg\" target=\"_blank\">CARABLANCA - panoramio<\/a> by Manuel Velazquez is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/3.0\/legalcode\" target=\"_blank\">CC BY 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Platyrrhines include the smallest of the monkeys, the marmosets and tamarins (Figure 6.29), all of which weigh less than one kilogram and live in cooperative family groups, wherein usually only one female reproduces and everyone else helps carry and raise the offspring. They are unusual primates in that they regularly produce twins. Marmosets and tamarins largely eat gums and saps, so these monkeys have evolved claw-like nails that enable them to cling to the sides of tree trunks like squirrels as well as special teeth that allow them to gnaw through bark. Except for the Goeldi\u2019s monkey, these small monkeys have one fewer molar than other platyrrhines, giving them a dental formula of 2:1:3:2.<\/p>\n<figure style=\"width: 428px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image32-1.jpg\" alt=\"Six marmoset and tamarin species.\" width=\"428\" height=\"470\" \/><figcaption class=\"wp-caption-text\">Figure 6.29: Clockwise from top right: golden-headed lion tamarin, pygmy marmoset, Goeldi\u2019s monkey, bare-eared marmoset, emperor tamarin, and common marmoset. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Callitrichinae_genus.jpg\" target=\"_blank\">Callitrichinae genus<\/a> by Miguelrangeljr is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/deed.en\" target=\"_blank\">CC BY-SA 3.0 License<\/a>. [Includes <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Wei%C3%9Fb%C3%BCschelaffe_(Callithrix_jacchus).jpg\" target=\"_blank\">Wei\u00dfb\u00fcschelaffe_(Callithrix_jacchus)<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Raymond\" target=\"_blank\">Raymond<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/\" target=\"_blank\">CC BY-SA 4.0<\/a>;\u00a0 <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Leontopithecus_chrysomelas_(portrait).jpg\" target=\"_blank\">Leontopithecus chrysomelas (portrait)<\/a> by Hans Hillewaert, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/\" target=\"_blank\">CC BY-SA 4.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Emperor_Tamarin_portrait_2_edit1.jpg\" target=\"_blank\">Emperor_Tamarin_portrait_2_edit1<\/a> by <a href=\"https:\/\/sites.google.com\/site\/thebrockeninglory\/\" target=\"_blank\">Brocken Inaglory<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/\" target=\"_blank\">CC BY-SA 4.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Dv%C3%A6rgsilkeabe_Callithrix_pygmaea.jpg\" target=\"_blank\">Dv\u00e6rgsilkeabe_Callithrix_pygmaea<\/a> by Malene Thyssen (User <a href=\"https:\/\/da.wikipedia.org\/wiki\/User:Malene\" target=\"_blank\">Malene<\/a>), <a href=\"https:\/\/en.wikipedia.org\/wiki\/GNU_Free_Documentation_License\" target=\"_blank\">GNU Free Documentation License<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Mico_argentatus_(portrait).jpg\" target=\"_blank\">Mico_argentatus_(portrait)<\/a> by Hans Hillewaert, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/\" target=\"_blank\">CC BY-SA 4.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Titi_Monkey.jpg\" target=\"_blank\">Titi Monkey<\/a> by Jeff Kubina, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/deed.en\" target=\"_blank\">CC BY-SA 2.0<\/a>].]<\/figcaption><\/figure>\n<p class=\"import-Normal\">The largest platyrrhines are a family that include spider monkeys, woolly spider monkeys, woolly monkeys, and howler monkeys (Figure 6.30). These monkeys can weigh up to 9\u201315 kg and have evolved prehensile tails that can hold their entire body weight. It is among this group that we see semi-brachiators, like the spider monkey (see Figure 6.13). To make them more efficient in this form of locomotion, spider monkeys evolved to not have thumbs so that their hands work more like hooks that can easily let go of branches while swinging. Howler monkeys are another well-known member of this group, earning their name due to their loud calls, which can be heard miles away. To make these loud vocalizations, howler monkeys have a specialized vocal system that includes a large larynx and hyoid bone. Howler monkeys are the most folivorous of the platyrrhines and are known for spending a large portion of their day digesting their food.<\/p>\n<figure style=\"width: 458px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image33-1.jpg\" alt=\"Four platyrrhine species.\" width=\"458\" height=\"457\" \/><figcaption class=\"wp-caption-text\">Figure 6.30: Clockwise from top right: howler monkey, woolly monkey, woolly spider monkey, and spider monkey. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Atelidae_Family.jpg\" target=\"_blank\">Atelidae Family<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Miguelrangeljr\" target=\"_blank\">Miguelrangeljr<\/a> is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0 License<\/a>. [Includes <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Ateles_marginatus_(Sao_Paulo_zoo).jpg\" target=\"_blank\">Ateles marginatus (Sao Paulo zoo)<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Miguelrangeljr\" target=\"_blank\">Miguelrangeljr<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Alouatta_caraya_male.JPG\" target=\"_blank\">Alouatta caraya male<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Miguelrangeljr\" target=\"_blank\">Miguelrangeljr<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Lagothrix_lagotricha_(walking).jpg\" target=\"_blank\">Lagothrix lagotricha (walking)<\/a> by Hans Hillewaert, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Brachyteles_hypoxanthus2.jpg\" target=\"_blank\">Brachyteles hypoxanthus2<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/42956474@N04\/with\/4133258867\/\" target=\"_blank\">Paulo B. Chaves<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/legalcode\" target=\"_blank\">CC BY 2.0<\/a>.]<\/figcaption><\/figure>\n<p class=\"import-Normal\">There are many other monkeys in Central and South America, including the gregarious capuchins (see Figure 6.28) and squirrel monkeys, the pair-living titi monkeys, and the nocturnal owl monkeys. There are also the seed-eating saki monkeys and uakaris. In many areas across Central and South America, multiple species of platyrrhines share the forests, with some even traveling together in association. According to molecular evidence, the diversity of platyrrhines that we see today seems to have originated about 25 million years ago (Schneider &amp; Sampaio 2015). Figure 6.31 summarizes the key traits of platyrrhines relative to the other infraorders of Haplorrhini.<\/p>\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<caption>Figure 6.31: Platyrrhini at a glance: Summary of the key traits we use to distinguish platyrrhines. Traits indicated with an * are those with exceptions detailed in the text. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\" target=\"_blank\">Platyrrhini at a glance table (Figure 5.29)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/caption>\n<tbody>\n<tr class=\"a3-R\">\n<td class=\"a3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Platyrrhini traits<\/strong><\/p>\n<\/td>\n<\/tr>\n<tr class=\"a3-R\">\n<td class=\"a3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Flat nose with rounded nostrils pointing to the side<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Highly arboreal<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Less sexually dimorphic on average<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">2:1:3:3 dental formula*<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Polymorphic colour vision*<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h4 class=\"import-Normal\"><em>Infraorder Catarrhini of Asia and Africa <\/em><\/h4>\n<figure style=\"width: 191px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image34.jpg\" alt=\"Wolf\u2019s guenon.\" width=\"191\" height=\"287\" \/><figcaption class=\"wp-caption-text\">Figure 6.32: A Wolf\u2019s guenon demonstrating a typical catarrhine nose with teardrop-shaped nostrils close together and pointed downward. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Wolf&apos;s_Guenon_Picking_Up_Food_(19095137693).jpg\" target=\"_blank\">Wolf's Guenon Picking Up Food (19095137693)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/8749778@N06\" target=\"_blank\">Eric Kilby<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\" target=\"_blank\">CC BY-SA 2.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Infraorder Catarrhini includes Superfamily Cercopithecoidea (the monkeys of Africa and Asia) and Superfamily Hominoidea (apes and humans). Nonhuman catarrhines are found all over Africa and South and Southeast Asia, with some being found as far north as Japan. The most northerly and southerly catarrhines are cercopithecoid monkeys. In contrast, apes are less tolerant of drier, more seasonal environments and so have a relatively restricted geographic range.<\/p>\n<p class=\"import-Normal\">Relative to other haplorrhine infraorders, catarrhines are distinguished by several characteristics. Catarrhines have a distinctive nose shape, with teardrop-shaped nostrils that are close together and point downward (Figure 6.32) and one fewer premolar than most other primates, giving us a dental formula of 2:1:2:3 (Figure 6.33). On average, catarrhines are the largest and most sexually dimorphic of all primates. Gorillas are the largest living primates, with males weighing up to 220 kg. The most sexually dimorphic of all primates are mandrills. Mandrill males not only have much more vibrant colouration than mandrill females but also have larger canines and can weigh up to three times more (Setchell Et al. 2001). The larger body size of catarrhines is related to the more terrestrial lifestyle of many members of this infraorder. In fact, the most terrestrial of living primates can be found in this group. Among all primates, vision is the most developed in catarrhines. Catarrhines independently evolved the same adaptation as howler monkeys in having each X chromosome with genes to distinguish both reds and yellows, so all male and female catarrhines are trichromatic, which is useful for these diurnal primates.<\/p>\n<figure style=\"width: 632px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image35-1.jpg\" alt=\"Platyrrhine, cercopithecoid, and hominoid mandibles.\" width=\"632\" height=\"331\" \/><figcaption class=\"wp-caption-text\">Figure 6.33: Catarrhines have two premolars whereas most other primate taxa (including platyrrhini) have three premolars. This image also shows one of the derived traits of cercopithecoids, their bilophodont molars, which differ from the more ancestral Y-5 molars of apes and humans. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\" target=\"_blank\">Platyrrhini vs. Catarrhini dentition<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\" target=\"_blank\">CC BY-NC-SA 4.0 License<\/a>. [Includes <a href=\"https:\/\/animaldiversity.org\/accounts\/Animalia\/specimens\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Cebus_apella\/lower_dorsal2216\/?start=135;f=subject::specimen::lower%20jaw\" target=\"_blank\">Cebus apella (brown capuchin)<\/a> at Animal Diversity Web by <a href=\"https:\/\/animaldiversity.org\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Hylobates_syndactylus\/lower_dorsal0097\/\" target=\"_blank\">Phil Myers<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\" target=\"_blank\">CC BY-NC-SA 3.0<\/a>; <a href=\"https:\/\/animaldiversity.org\/accounts\/Animalia\/specimens\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Lophocebus_albigena\/lower_dorsal2060\/?start=525;f=subject::specimen::lower%20jaw\" target=\"_blank\">Lophocebus albigena (gray-cheeked mangaby)<\/a> at Animal Diversity Web by <a href=\"https:\/\/animaldiversity.org\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Hylobates_syndactylus\/lower_dorsal0097\/\" target=\"_blank\">Phil Myers<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\" target=\"_blank\">CC BY-NC-SA 3.0<\/a>; <a href=\"https:\/\/animaldiversity.org\/accounts\/Primates\/specimens\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Hylobates_syndactylus\/lower_dorsal0097\/?start=105;f=subject::specimen::lower%20jaw\" target=\"_blank\">Symphalangus syndactylus (siamang)<\/a> at Animal Diversity Web by <a href=\"https:\/\/animaldiversity.org\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Hylobates_syndactylus\/lower_dorsal0097\/\" target=\"_blank\">Phil Myers<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\" target=\"_blank\">CC BY-NC-SA 3.0<\/a>.]<\/figcaption><\/figure>\n<p class=\"import-Normal\">The two superfamilies of catarrhines\u2014Superfamily Cercopithecoidea, the monkeys of Africa and Asia, and Superfamily Hominoidea, which includes apes and humans\u2014are believed to have split about 32 million years ago based on molecular evidence (Pozzi Et al. 2014). This fits with the fossil record, which shows evidence of these lineages by about 25 million years ago (see Chapters 8-9).<\/p>\n<h4 class=\"import-Normal\"><em>Superfamily Cercopithecoidea of Africa and Asia<\/em><\/h4>\n<figure style=\"width: 285px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image36-1.jpg\" alt=\"Pinkish ischial callosities on a crested black macaque.\" width=\"285\" height=\"214\" \/><figcaption class=\"wp-caption-text\">Figure 6.34: The second derived trait of cercopithecoids are their ischial callosities, shown here on a crested black macaque. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Sulawesi_trsr_DSCN0572_v1.JPG\" target=\"_blank\">Sulawesi trsr DSCN0572 v1<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Shankar_Raman\" target=\"_blank\">T. R. Shankar Ramanis<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0 License.<\/a><\/figcaption><\/figure>\n<p>Compared to hominoids, cercopithecoids have an ancestral quadrupedal body plan with two key derived traits. The first derived trait of cercopithecoids is their <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1422\">bilophodont<\/a> <\/strong>molars (\u201cbi\u201d meaning two, \u201cloph\u201d referring to ridge, and \u201cdont\u201d meaning tooth). If you refer back to Figure 6.33, you will see how the molars of cercopithecoids have four cusps arranged in a square pattern and have two ridges connecting them. It is thought that this molar enabled these monkeys to eat a wide range of foods, thus allowing them to live in habitats that apes cannot. The other key derived trait that all cercopithecoids share is having <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1424\">ischial callosities<\/a> <\/strong>(Figure 6.34). The ischium is the part of your pelvis that you are sitting on right now (see Appendix A: Osteology). In cercopithecoids, this part of the pelvis has a flattened surface that, in living animals, has callused skin over it. These function as seat pads for cercopithecoids, who often sit above branches when feeding and resting.<\/p>\n<figure style=\"width: 359px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image37-1.png\" alt=\"Areas of Europe, Asia, Africa, and Australia where cercopithecoids live.\" width=\"359\" height=\"277\" \/><figcaption class=\"wp-caption-text\">Figure 6.35: Geographic distribution of the cercopithecoid monkeys. Catarrhines have the widest geographic distribution due to the success of cercopithecoids who are found all across subsaharan Africa and southern Asia. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\" target=\"_blank\">Superfamily Cercopithecoidea map (Figure 5.33)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Elyssa Ebding at <a href=\"https:\/\/www.csuchico.edu\/geop\/geoplace\/index.shtml\" target=\"_blank\">GeoPlace, California State University, Chico<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p>Cercopithecoid monkeys are the most geographically widespread group of nonhuman primates (Figure 6.35). Since their divergence from hominoids, this monkey group has increased in numbers and diversity due, in part, to their fast reproductive rates. On average, cercopithecoids will reproduce every one to two years, whereas hominoids will reproduce once every four to nine years, depending on the taxon.<\/p>\n<figure style=\"width: 180px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image38-1.jpg\" alt=\"Two silver leaf monkeys hold orange-haired infants.\" width=\"180\" height=\"240\" \/><figcaption class=\"wp-caption-text\">Figure 6.36: Silver leaf monkey infants are born with orange fur, dramatically contrasting the adult coat colour of their mothers. After a few months, the infants gradually change colour to that of their parents. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Silverleaf_Monkey_(Kuala_Lumpur).jpg\" target=\"_blank\">Silverleaf Monkey (Kuala Lumpur)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/10815162@N07\" target=\"_blank\">Andrea Lai<\/a> from Auckland, New Zealand, is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/legalcode\" target=\"_blank\">CC BY 2.0 License.<\/a><\/figcaption><\/figure>\n<p>Cercopithecoidea is split into two groups, the leaf monkeys and the cheek-pouch monkeys. Both groups coexist in Asia and Africa; however, the majority of leaf monkey species live in Asia with only a few taxa in Africa. In contrast, only one genus of cheek-pouch monkey lives in Asia, and all the rest of them in Africa. As you can probably guess based on their names, the two groups differ in terms of diet. Leaf monkeys are primarily folivores, with some species eating a significant amount of seeds. Cheek-pouch monkeys tend to be more frugivorous or omnivorous, with one taxon, geladas, eating primarily grasses. The two groups also differ in some other interesting ways. Leaf monkeys tend to produce infants with <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1426\">natal coats<\/a><\/strong>\u2014infants whose fur is a completely different colour from their parents (Figure 6.36). Leaf monkeys are also known for having odd noses (Figure 6.37), and so they are sometimes called \u201codd-nosed monkeys.\u201d Cheek-pouch monkeys are able to pack food into their cheek pouches (Figure 6.38), thus allowing them to move to a location safe from predators or aggressive individuals of their own species where they can eat in peace.<\/p>\n<figure style=\"width: 408px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image39.jpg\" alt=\"Male proboscis monkey.\" width=\"408\" height=\"272\" \/><figcaption class=\"wp-caption-text\">Figure 6.37: Proboscis monkeys are one of several \u201codd-nosed\u201d leaf monkeys. Male proboscis monkeys, like this one, have large, pendulous noses, while females have much smaller noses. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Proboscis_monkey_(Nasalis_larvatus)_male_head.jpg\" target=\"_blank\">Proboscis monkey (Nasalis larvatus) male head<\/a> by <a href=\"https:\/\/www.sharpphotography.co.uk\/\" target=\"_blank\">Charles J Sharp<\/a> creator QS:P170,Q54800218 is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\" target=\"_blank\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<figure style=\"width: 414px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image40-1.jpg\" alt=\"Bonnet macaque with full cheek pouches.\" width=\"414\" height=\"275\" \/><figcaption class=\"wp-caption-text\">Figure 6.38: This bonnet macaque has filled its cheek pouches with food, an adaptation that is useful in transporting food to a safer location to eat. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Bonnet_macaque_DSC_0893.jpg\" target=\"_blank\">Bonnet macaque DSC 0893<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Shankar_Raman\" target=\"_blank\">T. R. Shankar Raman<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\" target=\"_blank\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<h4 class=\"import-Normal\"><em>Superfamily Hominoidea of Africa and Asia<\/em><\/h4>\n<figure style=\"width: 438px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image41.png\" alt=\"Areas of Europe, Asia, Africa, and Australia where hominoidea live.\" width=\"438\" height=\"339\" \/><figcaption class=\"wp-caption-text\">Figure 6.39: Geographic distribution of apes across Central and West Africa and Southeast Asia. Hominoids overlap geographically with cercopithecoid monkeys but have a lower tolerance for seasonal environments and so are found only in tropical forests across these regions. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\" target=\"_blank\">Superfamily Hominoidea map (Figure 5.38)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Elyssa Ebding at <a href=\"https:\/\/www.csuchico.edu\/geop\/geoplace\/index.shtml\" target=\"_blank\">GeoPlace, California State University, Chico<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Superfamily Hominoidea of Africa and Asia (Figure 6.39) includes the largest of the living primates: apes and humans. Whereas cercopithecoid monkeys have bilophodont molars, hominoids have the more ancestral <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1428\">Y-5 molars<\/a><\/strong>, which feature five cusps separated by a \u201cY\u201d-shaped groove pattern (see Figure 6.33). The Y-5 molar was present in the common ancestors of hominoids and cercopithecoids, thus it is the more ancestral molar pattern of the two. Hominoids differ the most from other primates in our body plans, due to the unique form of locomotion that hominoids are adapted for: brachiation (Figure 6.40).<\/p>\n<p>To successfully swing below branches, many changes to the body needed to occur. Hominoid arms are much longer than the legs to increase reach, and the lower back is shorter and less flexible to increase control when swinging. The torso, shoulders, and arms of hominoids have evolved to increase range of motion and flexibility (see again Figure 6.12). The clavicle, or collar bone, is longer to stabilize the shoulder joint out to the side, thus enabling us to rotate our arms 360 degrees. Hominoid rib cages are wider side to side and shallower front to back than those of cercopithecoids and we do not have tails, as tails are useful for balance when running on all fours but generally not useful while swinging. Hominoids also have modified ulnae, one of the two bones in the forearm (see Appendix A: Osteology). At the elbow end of the ulna, hominoids have a short <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1430\">olecranon process<\/a><\/strong>, which allows for improved extension in our arms. At the wrist end of the ulna, hominoids have a short <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1432\">styloid process<\/a><\/strong>, which enables us to have very flexible wrists, a trait critical for swinging. Both the olecranon process and styloid process are long in quadrupedal animals who carry much of their weight on their forelimbs when traveling and who therefore need greater stability rather than flexibility in those joints.<\/p>\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<caption>Figure 6.40: Quadrupedalism vs. brachiation: Summary of the key anatomical differences between a quadrupedal primate and one adapted for brachiation. To view these traits using photos of bones, check out the interactive skeletal websites in \u201cFurther Explorations\u201d below. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\" target=\"_blank\">Quadrupedalism vs. Brachiation table (Figure 5.39)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/caption>\n<thead>\n<tr>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Quadrupedalism<\/strong><\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Brachiation<\/strong><\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"a4-R\">\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Arm length vs. leg length<\/strong><\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">About equal<\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Arms are longer<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a4-R\">\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Shoulder position<\/strong><\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">More on the front<\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Out to the side<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a4-R\">\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Ribcage shape<\/strong><\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Deep front-to-back<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Narrow side-to-side<\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Shallow front-to-back<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Wide side-to-side<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a4-R\">\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Length of lower back<\/strong><\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Long<\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Short<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a4-R\">\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Collar bone length<\/strong><\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Short<\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Long<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a4-R\">\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Ulnar olecranon process<\/strong><\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Long<\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Short<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a4-R\">\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Ulnar styloid process<\/strong><\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Long<\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Short<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a4-R\">\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Tail<\/strong><\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Short to long<\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">None<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p class=\"import-Normal\">Apes and humans also differ from other primates in behaviour and life history characteristics. Hominoids all seem to show some degree of female dispersal at sexual maturity but, as you will learn in Chapter 7, it is more common that males leave. Some apes show males dispersing in addition to females, but the hominoid tendency for female dispersal is a bit unusual among primates. Our superfamily is also characterized by the most extended life histories of all primates. All members of this group take a long time to grow and reproduce much less frequently compared to cercopithecoids. The slow pace of this life history is likely related to why hominoids have decreased in diversity since they first evolved. Figure 6.41 summarizes the key traits of Infraorder Catarrhini and its two superfamilies. Today, there are only five types of hominoids left: gibbons and siamangs, orangutans, gorillas, chimpanzees and bonobos, and humans.<\/p>\n<table class=\"aligncenter\">\n<caption>Figure 6.41a: Catarrhini at a glance: Summary of key traits of the Infraorder Catarrhini. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\" target=\"_blank\">Catarrhini at a glance (Figure 5.40)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>. [Includes <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Duskyleafmonkey1.jpg\" target=\"_blank\">Duskyleafmonkey1<\/a> by <a href=\"https:\/\/www.the-ninth.com\/about\" target=\"_blank\">Robertpollai<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by\/3.0\/at\/deed.en\" target=\"_blank\">CC BY 3.0 AT<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Male_Bornean_Orangutan_-_Big_Cheeks.jpg\" target=\"_blank\">Male Bornean Orangutan - Big Cheeks<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/8749778@N06\" target=\"_blank\">Eric Kilby<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\" target=\"_blank\">CC BY-SA 2.0<\/a>.]<\/caption>\n<thead>\n<tr style=\"height: 22pt\">\n<td class=\"a5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\" colspan=\"2\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Infraorder Catarrhini<\/strong><\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"a5-R\" style=\"height: 22pt\">\n<td class=\"a5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\" colspan=\"2\">\n<p class=\"import-Normal\" style=\"text-align: center\">Downward facing, tear-drop shaped nostrils, close together<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Arboreal and more terrestrial taxa<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">On average, largest primates<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">On average, most sexually dimorphic taxonomic group<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">2:1:2:3 dental formula<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">All trichromatic<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<caption>Figure 6.41b: Characteristics used to distinguish between the two Catarrhini superfamilies. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\" target=\"_blank\">Catarrhini at a glance (Figure 5.40)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>. [Includes <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Duskyleafmonkey1.jpg\" target=\"_blank\">Duskyleafmonkey1<\/a> by <a href=\"https:\/\/www.the-ninth.com\/about\" target=\"_blank\">Robertpollai<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by\/3.0\/at\/deed.en\" target=\"_blank\">CC BY 3.0 AT<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Male_Bornean_Orangutan_-_Big_Cheeks.jpg\" target=\"_blank\">Male Bornean Orangutan - Big Cheeks<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/8749778@N06\" target=\"_blank\">Eric Kilby<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\" target=\"_blank\">CC BY-SA 2.0<\/a>.]<\/caption>\n<thead>\n<tr>\n<td class=\"a5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong><img class=\"alignnone\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image42-1.jpg\" alt=\"Dusky leaf monkey\" width=\"248\" height=\"186\" \/><\/strong><strong>Superfamily Cercopithecoidea<\/strong><\/p>\n<\/td>\n<td class=\"a5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong><img class=\"alignnone\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image43-1.jpg\" alt=\"Orangutan\" width=\"274\" height=\"183\" \/><\/strong><strong>Superfamily Hominoidea<\/strong><\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"a5-R\">\n<td class=\"a5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Wide geographic distribution<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Bilophodont molars<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Ischial callosities<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Reproduce every 1\u20132 years<\/p>\n<\/td>\n<td class=\"a5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Tropical forests of Africa and Asia<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Y-5 molars<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Adaptations for brachiation<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Reproduce every 4\u20139 years<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h4 class=\"import-Normal\"><em>Family <\/em>Hylobatidae <em>of Southeast Asia<\/em><\/h4>\n<figure style=\"width: 441px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image44-1.jpg\" alt=\"Siamang with outstretched arms.\" width=\"441\" height=\"294\" \/><figcaption class=\"wp-caption-text\">Figure 6.42: Siamangs are the largest of the Hylobatidae family. They are all black with a throat sac that can become inflated to give out loud calls. Credit: <a href=\"https:\/\/www.flickr.com\/photos\/suneko\/373310729\/\" target=\"_blank\">Shout (373310729)<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/suneko\/\" target=\"_blank\">su neko<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/\" target=\"_blank\">CC BY-SA 2.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">The number of genera in this group has been changing in recent years, but the taxa broadly encompasses gibbons and siamangs. Both are found across Southeast Asian tropical forests. Gibbons weigh, on average, about 13 pounds and tend to be more frugivorous, whereas siamangs are larger than gibbons and also more folivorous. Unlike the larger-bodied apes (orangutans, chimps, bonobos, and gorillas) who make nests to sleep in every night, gibbons and siamangs will develop callused patches on their ischium resembling ischial callosities. Gibbon species are quite variable in their colouration and markings, while siamangs are all black with big throat sacs that are used in their exuberant vocalizations (Figure 6.42). Both gibbons and siamangs live in pairs with very little sexual dimorphism, although males and females do differ in colouration in some gibbon species.<\/p>\n<h4 class=\"import-Normal\">Pongo<em> of Southeast Asia<\/em><\/h4>\n<p class=\"import-Normal\">The Genus <em>Pongo <\/em>refers to orangutans. These large red apes are found in Southeast Asia, with the two well-known species each living on the islands of Borneo and Sumatra. A third, very rare species, was recently discovered in Southern Sumatra (Nater Et al. 2017). Orangutans are highly frugivorous but will supplement their diet with leaves and bark when fruit is less available. As mentioned earlier, orangutans are the only diurnal, solitary taxon among primates and are extremely slow to reproduce, producing only one offspring about every seven to nine years. They are highly sexually dimorphic (Figure 6.43 a &amp; b), with fully developed, \u201cflanged\u201d males being approximately twice the size of females. These males have large throat sacs; long, shaggy coats; and cheek flanges. The skulls of male orangutans often feature a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1434\">sagittal crest<\/a><\/strong>, which is believed to function as additional attachment area for chewing muscles as well as a trait used in sexual competition (Balolia, Soligo, &amp; Wood 2017). An unusual feature of orangutan biology is <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1436\">male bimaturism<\/a><\/strong>. Male orangutans are known to delay maturation until one of the more dominant, flanged males disappears. The males that delay maturation are called \u201cunflanged\u201d males, and they can remain in this state for their entire life. Unflanged males resemble females in their size and appearance and will sneak copulations with females while avoiding the bigger, flanged males. Flanged and unflanged male orangutans represent alternative reproductive strategies, both of which successfully produce offspring (Utami Et al. 2002).<\/p>\n<p>&nbsp;<\/p>\n<\/div>\n<figure id=\"attachment_181-4\" aria-describedby=\"caption-attachment-181-4\" style=\"width: 1900px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-180 size-full\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/5.43.jpg\" alt=\"a. Female orangutan with infant. b. Male orangutan in a tree.\" width=\"1900\" height=\"800\" \/><figcaption id=\"caption-attachment-181-4\" class=\"wp-caption-text\">Figure 6.43: (a) A female orangutan eating fruit with her infant nearby and (b) a flanged adult male eating leaves. Male orangutans are about twice the size of females and have a longer coat length, cheek flanges, and throat sac. Credit: 6.43a. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Orang_Utan_(Pongo_pygmaeus)_female_with_baby_(8066259067).jpg\" target=\"_blank\">Orang Utan (Pongo pygmaeus) female with baby (8066259067)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/65695019@N07\" target=\"_blank\">Bernard DUPONT<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/\" target=\"_blank\">CC BY-SA 2.0 Licence<\/a>. 6.43b. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Orangutan_-Zoologischer_Garten_Berlin-8a.jpg\" target=\"_blank\">Orangutan -Zoologischer Garten Berlin-8a<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/37088680@N03\" target=\"_blank\">David Forsman<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/\" target=\"_blank\">CC BY 2.0 License<\/a>.<\/figcaption><\/figure>\n<div class=\"learning-objectives\">\n<h4 class=\"import-Normal\">Gorilla <em>of Africa<\/em><\/h4>\n<p class=\"import-Normal\">There are several species of gorillas that can be found across Central Africa. Gorilla males, like orangutan males, are about twice the size of female gorillas (Figures 6.44a &amp; b). When on the ground, gorillas use a form of quadrupedalism called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1438\">knuckle-walking<\/a><\/strong>, wherein the fingers are curled under and the weight is carried on the knuckles. Male gorillas have a large sagittal crest and large canines compared with females. Adult male gorillas are often called \u201csilverbacks\u201d because when they reach about twelve to thirteen years old, the hair on their backs turns silvery grey. Gorillas typically live in groups of one male and several females. Gorillas are considered folivorous, although some species can be more frugivorous depending on fruit seasonality (Remis 1997).<\/p>\n<\/div>\n<figure id=\"attachment_181-5\" aria-describedby=\"caption-attachment-181-5\" style=\"width: 1900px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-181 size-full\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/5.44.jpg\" alt=\"a. Female gorilla with offspring. b. Male gorilla.\" width=\"1900\" height=\"800\" \/><figcaption id=\"caption-attachment-181-5\" class=\"wp-caption-text\">Figure 6.44: (a) A female gorilla with her two offspring and (b) a silverback adult male. Male gorillas are about twice the size of females. They also differ from females in having a large sagittal crest and a silver back, which appears as they mature. Credit: 6.44a. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Enzo_naomi_echo.jpg\" target=\"_blank\">Enzo naomi echo<\/a> by Zoostar is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/3.0\/legalcode\" target=\"_blank\">CC BY 3.0 License<\/a>. 6.44b. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Male_gorilla_in_SF_zoo.jpg\" target=\"_blank\">Male gorilla in SF zoo<\/a> by Brocken Inaglory is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<div class=\"learning-objectives\">\n<h4 class=\"import-Normal\">Pan<em> of Africa<\/em><\/h4>\n<figure style=\"width: 252px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image49-1.jpg\" alt=\"Bonobo looks away from the camera.\" width=\"252\" height=\"222\" \/><figcaption class=\"wp-caption-text\">Figure 6.45: Bonobo (Pan paniscus). You can see the distinctive hair-part on this bonobo. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Bonobo_male_Jasongo_15yo_Twycross_582a_(2014_11_14_01_04_18_UTC).jpg\" target=\"_blank\">Bonobo male Jasongo 15yo Twycross 582a (2014 11 14 01 04 18 UTC)<\/a> by William H. Calvin is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\" target=\"_blank\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<p>The Genus <em>Pan <\/em>includes two species: <em>Pan troglodytes <\/em>(the common chimpanzee) and <em>Pan paniscus <\/em>(the bonobo). These species are separated by the Congo River, with chimpanzees ranging across West and Central Africa and bonobos located in a restricted area south of the Congo River. Chimpanzees and bonobos both have broad, largely frugivorous diets.The two species differ morphologically in that bonobos are slightly smaller, have their hair parted down the middle of their foreheads, and are born with dark faces (Figure 6.45). In contrast, chimpanzees do not have the distinctive parted hair and are born with light faces that darken as they mature (Figure 6.46). Chimpanzees and bonobos live in a grouping called a fission-fusion community, which you will learn more about in Chapter 6. Both species are moderately sexually dimorphic, with males about 20% larger than females. When on the ground, chimpanzees and bonobos knuckle-walk like gorillas do.<\/p>\n<figure style=\"width: 418px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image50-1.jpg\" alt=\"Female chimpanzee with offspring in a tree.\" width=\"418\" height=\"278\" \/><figcaption class=\"wp-caption-text\">Figure 6.46: A common chimpanzee (Pan troglodytes) female (centre) and her offspring. Note the pink face of the youngest individual. Bonobos are born with dark-skinned faces, but chimpanzees are born with pink faces that darken with age. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Chimpanzees_in_Uganda_(5984913059).jpg\" target=\"_blank\">Chimpanzees in Uganda (5984913059)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/57424551@N06\" target=\"_blank\">USAID Africa Bureau<\/a> uploaded by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Elitre\" target=\"_blank\">Elitre<\/a> is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\" target=\"_blank\">public domain<\/a>.<\/figcaption><\/figure>\n<h4 class=\"import-Normal\">Homo<\/h4>\n<p class=\"import-Normal\">The last member of the Hominoidea to discuss is our own taxon, Genus <em>Homo<\/em>. Later chapters will discuss the many extinct species of <em>Homo<\/em>, but today there is only one living species of <em>Homo, <\/em>our own species, <em>sapiens<\/em>. While it is interesting to focus on how humans differ from apes in many aspects of our morphology, behaviour, and life history, one objective of this chapter, and of biological anthropology in general, is to understand our place in nature. This means looking for aspects of human biology that link us to the taxonomic diversity we have discussed. To that end, here we will focus on similarities humans share with other hominoids.<\/p>\n<p class=\"import-Normal\">Like other hominoids, humans lack a tail and possess upper-body adaptations for brachiation. While our lower body has been modified for a bipedal gait, we are still able to swing from branches and throw a baseball, all thanks to our mobile shoulder joint. Humans, like other hominoids, also have a Y-5 cusp pattern on our molars. All hominoids, including humans, have an extended life history, taking time to grow and develop, and reproducing slowly over a long life span. Lastly, while humans show a great deal of variation across cultures, many human societies show tendencies for female dispersal (Burton Et al. 1996).<\/p>\n<p class=\"import-Normal\">Among the hominoids, humans show particular affinities with other members of the African Clade, <em>Pan <\/em>and <em>Gorilla<\/em>. Humans share over 96% of our DNA with gorillas (Scally Et al. 2012), and over 98% with <em>Pan <\/em>(Ebersberger Et al. 2002). Even without this strong genetic evidence, the African Clade of hominoids share many morphological similarities, including having wide-set eye sockets and backward-sweeping cheekbones. Today, <em>Pan<\/em> and <em>Gorilla<\/em> knuckle-walk when on the ground, and it has been suggested the last common ancestor of chimpanzees, bonobos, gorillas, and humans did as well (Richmond, Begun, &amp; Strait 2001). Further, humans, chimpanzees, and bonobos all live in fission-fusion social groups characterized by shared behaviours, like male cooperation in hunting and territoriality, as well as tool use.<\/p>\n<div class=\"textbox\">\n<h2 class=\"import-Normal\">Special Topic: Primates in Culture and Religion<\/h2>\n<p class=\"import-Normal\">One of the best parts of teaching anthropology for me is getting to spend time watching primates at zoos. What I also find interesting is watching people watch primates. I have very often heard a parent and child walk up to a chimpanzee enclosure and exclaim \u201cLook at the monkeys!\u201d The parent and child often don\u2019t know that a chimpanzee is not a monkey, nor are they likely to know that chimpanzees share more than 98% of their DNA with us. What strikes me as significant is that, although most people do not know the difference between a monkey, an ape, and a lemur, they nonetheless recognize something in the animals as being similar to themselves. In fact, recognition of similarities between humans and other primates is very ancient, dating back far earlier than Linnaeus. For many of us, we only ever get to see primates in zoos and animal parks, but in many areas of the world, humans have coexisted with these animals for thousands of years. In areas where humans and primates have a long, shared history, nonhuman primates often play key roles in creation myths and cultural symbolism.<\/p>\n<p class=\"import-Normal\">Hamadryas baboons feature significantly in Ancient Egyptian iconography. Ancient Egyptian deities and beliefs transformed over time, as did the role of hamadryas baboons. Early on, baboons were thought to represent dead ancestors, and one monkey deity, called Babi or Baba, was thought to feed off of dead souls. Later, baboons became the totem animal for Thoth, the deity of science, writing, wisdom, and measurement, who also wrote the Book of the Dead. Sunbathing hamadryas baboons led ancient Egyptians to associate them with Ra, the sun god, who was the son of Thoth. During mummification, human organs were removed and put into canopic jars, one of which was topped with the head of the baboon-headed god, Hapi. Hamadryas baboons were also often kept as pets, as depicted in hieroglyphics, and occasionally mummified as well.<\/p>\n<p class=\"import-Normal\">On Madagascar, indris and aye-ayes play roles in the creation myths and omens of local people.There are many myths regarding the origins of indris and their relationship to humans, including one where two brothers living in the forest separated, with one brother leaving the forest and becoming a human while the other stayed in the forest to become the indri. Like humans, indris have long legs, no tail, and upright posture. They are considered sacred and are therefore protected. Unfortunately, the aye-aye is not treated with the same reverence. Because of their unusual appearance (see Figure 6.15), aye-ayes are seen as omens of death.They are usually killed when encountered because it is believed that someone will die if an aye-aye points at them.<\/p>\n<p class=\"import-Normal\">In India, monkeys play a key role in the Hindu religion. Hanuman, who resembles a monkey, is a key figure in the Ramayana. Hanuman is thought to be a guardian deity, and so local monkeys like Hanuman langurs and macaques are protected in India (Figure 6.47). In Thailand, where Hinduism is also practiced, the Hindu reverence for monkeys extends to \u201cmonkey feasts,\u201d where large quantities of food are spread out in gratitude to the monkeys for bringing good fortune.<\/p>\n<figure style=\"width: 308px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image51-1.jpg\" alt=\"Three macaques outside a temple in India.\" width=\"308\" height=\"261\" \/><figcaption class=\"wp-caption-text\">Figure 6.47: Because of important monkey-like figures in the Hindu religion, macaques are protected in India and often live near temples where they are fed by local peoples. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Macaque_India_4.jpg\" target=\"_blank\">Macaque India 4<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Mosmas\" target=\"_blank\">Thomas Schoch<\/a> (<a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Mosmas\" target=\"_blank\">Mosmas<\/a>) is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/\" target=\"_blank\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">The people of Japan have coexisted with Japanese macaques for thousands of years, and so monkeys play key roles in both of the major Japanese religions. In the Shinto religion, macaques are thought of as messengers between the spirit world and humans, and monkey symbols are thought to be good luck. The other major religion in Japan is Buddhism, and monkeys play a role in symbolism of this religion as well. The \u201cThree Wise Monkeys\u201d who see no evil, speak no evil, and hear no evil derive from Buddhist iconography of monkeys.<\/p>\n<p class=\"import-Normal\">In Central and South America, monkeys feature often in Mayan and Aztec stories. In the Mayan creation story, the Popol Vuh, the \u201chero brothers,\u201d are actually a howler monkey and a spider monkey, who represent ancestors of humans in the story. In the Aztec religion, spider monkeys are associated with the god of arts, pleasure, and playfulness. A spider monkey is also represented in a Peruvian Nazca geoglyph, a large design made on the ground by moving rocks.<\/p>\n<p class=\"import-Normal\">In many of these regions today, the relationships between humans and nonhuman primates are complicated. The bushmeat and pet trades make these animals valuable at the expense of many animals\u2019 lives, and in some areas, nonhuman primates have become pests who raid crop fields and consume valuable foods. All of this has led to the development of a new subarea of anthropology called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1440\">Ethnoprimatology<\/a><\/strong>, which involves studying the political, economic, symbolic, and practical relationships between humans and nonhuman primates.This field highlights the particular challenges for humans of having to coexist with animals with whom we share so much in common. It also provides insight into some of the challenges facing primate conservation efforts (see Appendix B: Primate Conservation).<\/p>\n<\/div>\n<h2 class=\"import-Normal\">Summary<\/h2>\n<p class=\"import-Normal\">The Order Primates is a diverse and fascinating group of animals united in sharing a suite of characteristics\u2014visual specialization, grasping hands and feet, large brains, and extended life histories\u2014that differentiates us from other groups of mammals. In this chapter, we surveyed the major taxonomic groups of primates, discussing where humans fit among our close relatives as well as discovering that primates are interesting animals in their own right. We discussed a range of key traits used to distinguish between the many taxa of living primates, including dietary, locomotor, and behavioural characteristics. Because of our long, shared evolutionary history with these animals, nonhuman primates provide a crucial resource for understanding our current biology. In Chapter 7, you will discover the fascinating and complex social behaviours of nonhuman primates, which provide further insight into our evolutionary biology.<\/p>\n<\/div>\n<h2>Expand your view<\/h2>\n<p>For a deeper look into primate conservation and contemporary issues of endangerment\/extinction see <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/appendix-b-primate-conservation\/\">Appendix B<\/a><\/p>\n<p>&nbsp;<\/p>\n<div class=\"learning-objectives\">\n<div class=\"textbox shaded\">\n<h2 class=\"import-Normal\">Review Questions<\/h2>\n<ul>\n<li class=\"import-Normal\">Why does the field of anthropology, a field dedicated to the study of humans, include the study of nonhuman animals? What can we learn from nonhuman primates?<\/li>\n<li class=\"import-Normal\">Why is it important to try to place taxa into a clade classification rather than groupings based on grade? Can you think of an example?<\/li>\n<li class=\"import-Normal\">One of the important goals of an introductory biological anthropology course is to teach you about your place in nature. What is the full taxonomic classification of humans, and what are some of the traits we have of each of these categories?<\/li>\n<li class=\"import-Normal\">When you have seen primates in person, did you observe any facial expressions, behaviours, or physical traits that seemed familiar to you? If so, which ones and why?<\/li>\n<li class=\"import-Normal\">Draw out a tree showing the major taxonomic group of primates described here, making sure to leave room in between each level. Underneath each taxon, list some of the key features of this group so that you can compare traits between groups.<\/li>\n<\/ul>\n<\/div>\n<h2 class=\"import-Normal\">Key Terms<\/h2>\n<p class=\"import-Normal\"><strong>Activity pattern<\/strong>: Refers to the time of day an animal is typically active.<\/p>\n<p class=\"import-Normal\"><strong>African clade<\/strong>: A grouping that includes gorillas, chimpanzees, bonobos, humans, and their extinct relatives.<\/p>\n<p class=\"import-Normal\"><strong>Analogy<\/strong>: When two or more taxa exhibit similar traits that have evolved independently, the similar traits evolve due to similar selective pressures. (Also sometimes called convergent evolution, parallel evolution, or homoplasy.)<\/p>\n<p class=\"import-Normal\"><strong>Ancestral trait<\/strong>: A trait that has been inherited from a distant ancestor.<\/p>\n<p class=\"import-Normal\"><strong>Arboreal<\/strong>: A descriptor for an organism that spends most of its time in trees.<\/p>\n<p class=\"import-Normal\"><strong>Asian clade<\/strong>: A grouping that includes orangutang and their extinct relatives.<\/p>\n<p class=\"import-Normal\"><strong>Bilophodont<\/strong>: Molar pattern of cercopithecoid monkeys in which there are usually four cusps that are arranged in a square pattern and connected by two ridges.<\/p>\n<p class=\"import-Normal\"><strong>Bipedalism<\/strong>: Walking on two legs.<\/p>\n<p class=\"import-Normal\"><strong>Brachiation<\/strong>: A form of locomotion in which the organism swings below branches using the forelimbs.<\/p>\n<p class=\"import-Normal\"><strong>Bunodont<\/strong>: Low, rounded cusps on the cheek teeth.<\/p>\n<p class=\"import-Normal\"><strong>Canines<\/strong>: In most primates, these are the longest of the teeth, often conical in shape and used as a weapon against predators or others of their species.<\/p>\n<p class=\"import-Normal\"><strong>Cathemeral<\/strong>: Active throughout the 24-hour period.<\/p>\n<p class=\"import-Normal\"><strong>Clade<\/strong>: A grouping based on ancestral relationships; a branch of the evolutionary tree.<\/p>\n<p class=\"import-Normal\"><strong>Cusps<\/strong>: The bumps on the chewing surface of the premolars and molars, which can be quite sharp in some species.<\/p>\n<p class=\"import-Normal\"><strong>Dental formula<\/strong>: The number of each type of tooth in one quadrant of the mouth, written as number of incisors: canines: premolars: molars.<\/p>\n<p class=\"import-Normal\"><strong>Derived trait<\/strong>: A trait that has been recently modified, most helpful when assigning taxonomic classification.<\/p>\n<p class=\"import-Normal\"><strong>Diastema<\/strong>: A space between the teeth, usually for large canines to fit when the mouth is closed.<\/p>\n<p class=\"import-Normal\"><strong>Dichromatic<\/strong>: Being able to see only blues and greens.<\/p>\n<p class=\"import-Normal\"><strong>Diurnal<\/strong>: Active during the day.<\/p>\n<p class=\"import-Normal\"><strong>Dry nose<\/strong>: The nose and upper lip are separated and the upper lip can move independently; sometimes referred to as a \u201chairy\u201d or \u201cmobile\u201d upper lip.<\/p>\n<p class=\"import-Normal\"><strong>Ethnoprimatology<\/strong>: A subarea of anthropology that studies the complexities of human-primate relationships in the modern environment.<\/p>\n<p class=\"import-Normal\"><strong>Evolutionary trade-off<\/strong>: When an organism, which is limited in the time and energy it can put into aspects of its biology and behaviour, is shaped by natural selection to invest in one adaptation at the expense of another.<\/p>\n<p class=\"import-Normal\"><strong>Faunivorous<\/strong>: Having a diet consisting entirely of animal matter: insects, eggs, lizards, etc.<\/p>\n<p class=\"import-Normal\"><strong>Folivore<\/strong>: Having a diet consisting primarily of leaves.<\/p>\n<p class=\"import-Normal\"><strong>Fovea<\/strong>: A depressed area in the retina at the back of the eye containing a concentration of cells that allow one to focus on objects very close to one\u2019s face.<\/p>\n<p class=\"import-Normal\"><strong>Frugivore<\/strong>: Having a diet consisting primarily of fruit.<\/p>\n<p class=\"import-Normal\"><strong>Generalized trait<\/strong>: A trait that is useful for a wide range of tasks.<\/p>\n<p class=\"import-Normal\"><strong>Grade<\/strong>: A grouping based on overall similarity in lifestyle, appearance, and behaviour.<\/p>\n<p class=\"import-Normal\"><strong>Grooming claw<\/strong>: A claw present on the second pedal digit in strepsirrhines.<\/p>\n<p class=\"import-Normal\"><strong>Gummivore<\/strong>: Having a diet consisting primarily of gums and saps.<\/p>\n<p class=\"import-Normal\"><strong>Heterodont<\/strong>: Having different types of teeth.<\/p>\n<p class=\"import-Normal\"><strong>Homology<\/strong>: When two or more taxa share characteristics because they inherited them from a common ancestor.<\/p>\n<p class=\"import-Normal\"><strong>Hone<\/strong>: When primates sharpen their canines by wearing them on adjacent teeth.<\/p>\n<p class=\"import-Normal\"><strong>Incisors<\/strong>: The spatula-shaped teeth at the front of the mouth.<\/p>\n<p class=\"import-Normal\"><strong>Insectivore<\/strong>: Having a diet consisting primarily of insects.<\/p>\n<p class=\"import-Normal\"><strong>Ischial callosities<\/strong>: Modified seat bones of the pelvis that are flattened and over which calluses form; function as seat pads for sitting and resting atop branches.<\/p>\n<p class=\"import-Normal\"><strong>Knuckle-walking<\/strong>: A form of quadrupedal movement used by <em>Gorilla<\/em> and <em>Pan<\/em> when on the ground, wherein the front limbs are supported on the knuckles of the hands.<\/p>\n<p class=\"import-Normal\"><strong>Life history<\/strong>: Refers to an organism\u2019s pace of growth, reproduction, lifespan, etc.<\/p>\n<p class=\"import-Normal\"><strong>Locomotion<\/strong>: How an organism moves around.<\/p>\n<p class=\"import-Normal\"><strong>Male bimaturism<\/strong>: Refers to the alternative reproductive strategies in orangutans in which males can delay maturation, sometimes indefinitely, until a fully mature, \u201cflanged\u201d male disappears.<\/p>\n<p class=\"import-Normal\"><strong>Molars<\/strong>: The largest teeth at the back of the mouth; used for chewing. In primates, these teeth usually have between three and five cusps.<\/p>\n<p class=\"import-Normal\"><strong>Monochromatic<\/strong>: Being able to see only in shades of light to dark, no colour.<\/p>\n<p class=\"import-Normal\"><strong>Monomorphic<\/strong>: When males and females of a species do not exhibit significant sexual dimorphism.<\/p>\n<p class=\"import-Normal\"><strong>Natal coat<\/strong>: Refers to the contrasting fur colour of baby leaf monkeys compared to adults.<\/p>\n<p class=\"import-Normal\"><strong>Nocturnal<\/strong>: Active at night.<\/p>\n<p class=\"import-Normal\"><strong>Olecranon process<\/strong>: Bony projection at the elbow end of the ulna.<\/p>\n<p class=\"import-Normal\"><strong>Opposable thumb <\/strong>or <strong>opposable big toe<\/strong>: Having thumbs and toes that go in a different direction from the rest of the fingers, allows for grasping with hands and feet.<\/p>\n<p class=\"import-Normal\"><strong>Pentadactyly<\/strong>: Having five digits or fingers and toes.<\/p>\n<p class=\"import-Normal\"><strong>Polymorphic colour vision<\/strong>: A system in which individuals of a species vary in their abilities to see colour. In primates, it refers to males being dichromatic and females being either trichromatic or dichromatic.<\/p>\n<p class=\"import-Normal\"><strong>Postorbital bar<\/strong>: A bony ring that surrounds the eye socket, open at the back.<\/p>\n<p class=\"import-Normal\"><strong>Postorbital closure\/plate<\/strong>: A bony plate that provides protection to the side and back of the eye.<\/p>\n<p class=\"import-Normal\"><strong>Prehensile tail<\/strong>: A tail that is able to hold the full body weight of an organism, which often has a tactile pad on the underside of the tip for improved grip.<\/p>\n<p class=\"import-Normal\"><strong>Premolars<\/strong>: Smaller than the molars, used for chewing. In primates, these teeth usually have one or two cusps.<\/p>\n<p class=\"import-Normal\"><strong>Quadrupedalism<\/strong>: Moving around on all fours.<\/p>\n<p class=\"import-Normal\"><strong>Rhinariums<\/strong>: Wet noses; resulting from naked skin of the nose which connects to the upper lip and smell-sensitive structures along the roof of the mouth.<\/p>\n<p class=\"import-Normal\"><strong>Sagittal crest<\/strong>: A bony ridge along the top\/middle of the skull, used for attachment of chewing muscles.<\/p>\n<p class=\"import-Normal\"><strong>Scent marking<\/strong>: The behaviour of rubbing scent glands or urine onto objects as a way of communicating with others.<\/p>\n<p class=\"import-Normal\"><strong>Semi-brachiation<\/strong>: A form of locomotion in which an organism swings below branches using a combination of forelimbs and prehensile tail.<\/p>\n<p class=\"import-Normal\"><strong>Sexually dimorphic<\/strong>: When a species exhibits sex differences in morphology, behaviour, hormones, and\/or colouration.<\/p>\n<p class=\"import-Normal\"><strong>Shearing crests<\/strong>: Sharpened ridges that connect cusps on a bilophodont molar.<\/p>\n<p class=\"import-Normal\"><strong>Specialized trait<\/strong>: A trait that has been modified for a specific purpose.<\/p>\n<p class=\"import-Normal\"><strong>Styloid process of ulna<\/strong>: A bony projection of the ulna at the end near the wrist.<\/p>\n<p class=\"import-Normal\"><strong>Tactile pads<\/strong>: Sensitive skin at the fingertips for sense of touch. Animals with a prehensile tail have a tactile pad on the underside of the tail as well.<\/p>\n<p class=\"import-Normal\"><strong>Tapetum lucidum<\/strong>: Reflecting layer at the back of the eye that magnifies light.<\/p>\n<p class=\"import-Normal\"><strong>Terrestrial<\/strong>: A descriptor for an organism that spends most of its time on the ground.<\/p>\n<p class=\"import-Normal\"><strong>Tetrachromatic<\/strong>: Having the ability to see reds, yellows, blues, greens, and ultraviolet.<\/p>\n<p class=\"import-Normal\"><strong>Tooth comb<\/strong> or <strong>dental comb<\/strong>: A trait of the front, lower teeth of strepsirrhines in which, typically, the four incisors and canines are long and thin and protrude outward.<\/p>\n<p class=\"import-Normal\"><strong>Trichromatic colour vision<\/strong>: Being able to distinguish yellows and reds in addition to blues and greens.<\/p>\n<p class=\"import-Normal\"><strong>Vertical clinging and leaping<\/strong>: A locomotor pattern in which animals are oriented upright while clinging to vertical branches, push off with hind legs, and land oriented upright on another vertical branch.<\/p>\n<p class=\"import-Normal\"><strong>Y-5 molar<\/strong>: Molar cusp pattern in which five molar cusps are separated by a \u201cY\u201d-shaped groove pattern.<\/p>\n<h2 class=\"import-Normal\">For Further Exploration<\/h2>\n<p class=\"import-Normal\"><a href=\"https:\/\/animaldiversity.org\/accounts\/Primates\/specimens\/\">Animal Diversity Web<\/a>. This website is hosted by the Zoology Department at the University of Michigan. It has photographs of skulls, teeth, hands, arms, and feet of many primate species.<\/p>\n<p class=\"import-Normal\"><a href=\"https:\/\/www.eskeletons.org\">eSkeletons<\/a>. This website is hosted by the Department of Anthropology at University of Texas, Austin. It is an interactive website where you can compare specific bones from different species of primates.<\/p>\n<p class=\"import-Normal\">Fleagle, John G. 2013. <em>Primate Adaptation and Evolution<\/em>. Third edition. San Diego: Academic Press.<\/p>\n<p class=\"import-Normal\">Fuentes, Agust\u00edn, and Kimberley J. Hockings. 2010. \u201cThe Ethnoprimatological Approach in Primatology.\u201d <em>American Journal of Primatology<\/em> 72 (10): 841\u2013847.<\/p>\n<p class=\"import-Normal\">Rowe, Noel. 1996. <em>Pictorial Guide to the Living Primates<\/em>. Charlestown, RI: Pogonias Press.<\/p>\n<p class=\"import-Normal\">Whitehead, Paul F., William K. Sacco, and Susan B. Hochgraf. 2005. <em>A Photographic Atlas for Physical Anthropology<\/em>. Englewood, CO: Morton Publishing.<\/p>\n<h2>References<\/h2>\n<p class=\"import-Normal\">Balolia, Katharine L., Christophe Soligo, and Bernard Wood. 2017. \u201cSagittal Crest Formation in Great Apes and Gibbons.\u201d <em>Journal of Anatomy<\/em> 230 (6): 820\u2013832.<\/p>\n<p class=\"import-Normal\">Bininda-Emonds, Olaf R., Marcel Cardillo, Kate E. Jones, Ross D. E. MacPhee, Robin M. D. Beck, Richard Grenyer, Samantha A. Price, Rutger A. Vos, John L. Gittleman, and Andy Purvis. 2007. \u201cThe Delayed Rise of Present-Day Mammals.\u201d <em>Nature<\/em> 446 (7135): 507\u2013512.<\/p>\n<p class=\"import-Normal\">Burton, Michael L., Carmella C. Moore, John W. M. Whiting, A. Kimball Romney, David F. Aberle, Juan A. Barcelo, Malcolm M. Dow, et al. 1996. \u201cRegions Based on Social Structure.\u201d <em>Current Anthropology<\/em> 37 (1): 87\u2013123.<\/p>\n<p class=\"import-Normal\">Chivers, David J., and C. M. Hladik. 1980. \u201cMorphology of the Gastrointestinal Tract in Primates: Comparisons with Other Mammals in Relation to Diet.\u201d <em>Journal of Morphology<\/em> 166 (3): 337\u2013386.<\/p>\n<p class=\"import-Normal\">Clutton-Brock, T. H., and Paul H. Harvey. 1980. \u201cPrimates, Brains, and Ecology.\u201d <em>Journal of Zoology<\/em> 190 (3): 309\u2013323.<\/p>\n<p class=\"import-Normal\">Dunbar, Robin I. M. 1998. \u201cThe Social Brain Hypothesis.\u201d <em>Evolutionary Anthropology<\/em> 6 (5): 178\u2013190.<\/p>\n<p class=\"import-Normal\">Ebersberger, Ingo, Dirk Metzler, Carsten Schwarz, and Svante P\u00e4\u00e4bo. 2002. \u201cGenomewide Comparison of DNA Sequences Between Humans and Chimpanzees.\u201d <em>American Journal of Human Genetics<\/em> 70 (6): 1490\u20131497.<\/p>\n<p class=\"import-Normal\">Jameson, Natalie M., Zhuo-Cheng Hou, Kirstin N. Sterner, Amy Weckle, Morris Goodman, Michael E. Steiper, and Derek E. Wildman. 2011. \u201cGenomic Data Reject the Hypothesis of a Prosimian Primate Clade.\u201d <em>Journal of Human Evolution<\/em> 61 (3): 295\u2013305.<\/p>\n<p class=\"import-Normal\">Kawamura, Shoji, Chihiro Hiramatsu, Amanda D. Melin, Colleen M. Schaffner, Filippo Aureli, and Linda M. Fedigan. 2012. \u201cPolymorphic Color Vision in Primates: Evolutionary Considerations.\u201d In <em>Post-Genome Biology of Primates<\/em>, edited by H. Irai, H. Imai, and Y. Go, 93\u2013120. Tokyo: Springer.<\/p>\n<p class=\"import-Normal\">Matsui, Atsushi, Felix Rakotondraparany, Isao Munechika, Masami Hasegawa, and Satoshi Horai. 2009. \u201cMolecular Phylogeny and Evolution of Prosimians Based on Complete Sequences of Mitochondrial DNAs.\u201d <em>Gene<\/em> 441 (1\u20132): 53\u201366.<\/p>\n<p class=\"import-Normal\">Nater, Alexander, Maja P. Mattle-Greminger, Anton Nurcahyo, Matthew G. Nowak, Marc de Manuel, Tariq Desai, Colin Groves, et al. 2017. \u201cMorphometric, Behavioral, and Genomic Evidence for a New Orangutan Species.\u201d <em>Current Biology<\/em> 27 (22): 3487\u20133498.<\/p>\n<p class=\"import-Normal\">Pozzi, Luca, Jason A. Hodgson, Andrew S. Burrell, Kirstin N. Sterner, Ryan L. Raaum, and Todd R. Disotell. 2014. \u201cPrimate Phylogenetic Relationships and Divergence Dates Inferred from Complete Mitochondrial Genomes.\u201d <em>Molecular Phylogenetics and Evolution<\/em> 75: 165\u2013183.<\/p>\n<p class=\"import-Normal\">Remis, Melissa J. 1997. \u201cWestern Lowland Gorillas (<em>Gorilla gorilla gorilla<\/em>) as Seasonal Frugivores: Use of Variable Resources.\u201d <em>American Journal of Primatology<\/em> 43 (2): 87\u2013109.<\/p>\n<p class=\"import-Normal\">Richmond, Brian G., David R. Begun, and David S. Strait. 2001. \u201cOrigin of Human Bipedalism: The Knuckle\u2010Walking Hypothesis Revisited.\u201d <em>American<\/em> <em>Journal of Physical Anthropology<\/em> 116 (S33): 70\u2013105.<\/p>\n<p class=\"import-Normal\">Robson, Shannen L., Carel P. van Schaik, and Kristen Hawkes. 2006. \u201cThe Derived Features of Human Life History.\u201d In <em>The Evolution of Human Life History, edited by Kristen Hawkes and Richard R. Paine, <\/em>17\u201344. Santa Fe: SAR Press.<\/p>\n<p class=\"import-Normal\">Scally, Aylwyn, Julien Y. Dutheil, LaDeana W. Hillier, Gregory E. Jordan, Ian Goodhead, Javier Herrero, Asger Hobolth, et al. 2012. \u201cInsights into Hominid Evolution from the Gorilla Genome Sequence.\u201d <em>Nature<\/em> 483 (7388): 169\u2013175.<\/p>\n<p class=\"import-Normal\">Schneider, Horacio, and Iracilda Sampaio. 2015. \u201cThe Systematics and Evolution of New World Primates: A Review.\u201d <em>Molecular Phylogenetics and Evolution<\/em> 82 (B): 348\u2013357.<\/p>\n<p class=\"import-Normal\">Setchell, Joanna M., Phyllis C. Lee, E. Jean Wickings, and Alan F. Dixson. 2001. \u201cGrowth and Ontogeny of Sexual Size Dimorphism in the Mandrill (<em>Mandrillus sphinx<\/em>).\u201d <em>American Journal of Physical Anthropology<\/em> 115 (4): 349\u2013360.<\/p>\n<p class=\"import-Normal\">Utami, Sri Suci, Beno\u00eet Goossens, Michael W. Bruford, Jan R. de Ruiter, and Jan A. R. A. M. van Hooff. 2002. \u201cMale Bimaturism and Reproductive Success in Sumatran Orang-utans.\u201d <em>Behavioral Ecology<\/em> 13 (5): 643\u2013652.<\/p>\n<p class=\"import-Normal\">Vasey, Natalie. 2006. \u201cImpact of Seasonality and Reproduction on Social Structure, Ranging Patterns, and Fission\u2013Fusion Social Organization in Red Ruffed Lemurs.\u201d In <em>Lemurs: Ecology and Adaptation<\/em>, edited by Lisa Gould and Michelle L. Sauther, 275\u2013304. New York: Springer.<\/p>\n<p class=\"import-Normal\">Wright, Patricia C. 1999. \u201cLemur Traits and Madagascar Ecology: Coping with an Island Environment.\u201d <em>American Journal of Physical Anthropology<\/em> 110 (S29): 31\u201372.<\/p>\n<h2>Acknowledgements<\/h2>\n<p class=\"import-Normal\">The author would very much like to thank the editors for the opportunity to contribute to this textbook, along with anonymous reviewers who provided useful feedback on earlier drafts of this chapter. She would particularly like to thank Karin Enstam Jaffe for her support and encouragement during the writing of this chapter and its revision. Most of all, the author would like to thank all of the Introduction to Biological Anthropology students that she has had over the years who have listened to her lecture endlessly on these animals that she finds so fascinating and who have helped her to hone her pedagogy in a field that she loves.<\/p>\n<\/div>\n<\/div>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1695_1854\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1695_1854\"><div tabindex=\"-1\"><div class=\"__UNKNOWN__\">\n<div class=\"textbox\">\n<p>Learn more about <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/about-the-authors\/\">authors and editors<\/a>,<a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/student-contributors\/\"> Hess' student contributions<\/a>, and <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/versioning-history\/\">versioning history<\/a>.<\/p>\n<p>&lt;!-- marker for new place of <\/p><\/div>\n<p> --&gt;\n<\/p><\/div>\n<div class=\"textbox textbox--learning-objectives\">\n<header class=\"textbox__header\">\n<h2 class=\"textbox__title\">Learning Objectives<\/h2>\n<\/header>\n<div class=\"textbox__content\">\n<ul>\n<li class=\"import-Normal\">Describe how studying nonhuman primates is important in anthropology.<\/li>\n<li class=\"import-Normal\">Compare two ways of categorizing taxa: grades and clades.<\/li>\n<li class=\"import-Normal\">Define different types of traits used to evaluate primate taxa.<\/li>\n<li class=\"import-Normal\">Identify key ways that primates differ from other mammals.<\/li>\n<li class=\"import-Normal\">Distinguish between the major primate taxa using their key characteristics.<\/li>\n<li class=\"import-Normal\">Describe your place in nature by learning your taxonomic classification.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<p class=\"import-Normal\">You may be wondering why a field dedicated to the study of humans includes discussions of nonhuman animals. Our primary goal in biological anthropology is to understand how humans are similar to and different from the rest of the natural world, why we have the traits we have, and how we got to be the way we are. But to fully grasp our place in nature, we must look to our closest living relatives, the nonhuman primates. In this chapter, we focus on the organization and diversity within the Order Primates.<\/p>\n<h2 class=\"import-Normal\">Studying Primates in Biological Anthropology<\/h2>\n<p class=\"import-Normal\">Primates are one of at least twenty Orders belonging to the Class Mammalia, and probably one of the oldest. One genetic estimate puts the origin of primates at approximately 91 million years ago (mya), predating the extinction of the dinosaurs (Bininda-Emonds Et al. 2007). Today, the Order Primates is a diverse group of animals that includes lemurs and lorises, tarsiers, monkeys, apes, and humans, all of which are united in sharing a suite of anatomical, behavioural, and life history characteristics. While nonhuman primates are fascinating animals in their own right, their close relationship to humans makes them ideal for studying humans via <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_944\">homology<\/a>, <\/strong>looking at traits that are shared between taxa because they inherited the trait from a common ancestor. For example, humans (genus <em>Homo<\/em>) and chimpanzees (genus <em>Pan<\/em>) both share the trait of male cooperation in hunting. This trait\u2014along with many others that chimpanzees and humans share\u2014is likely homologous<em>, <\/em>meaning it was probably passed down from the last common ancestor of <em>Homo<\/em> and <em>Pan, <\/em>which lived about 6\u20138 million years ago.<\/p>\n<p class=\"import-Normal\">Nonhuman primates also make excellent comparators for learning about humans via <strong>analogy<\/strong>. Many nonhuman primates live in environments similar to those in which our ancestors lived and therefore exhibit traits similar to what we see in humans. For example, baboons and humans both have long legs. In humans, this is because about 1.7 million years ago, our ancestors moved into savanna habitats where longer legs helped them move more efficiently over long distances. Baboons, who also live in savanna habitats, independently evolved longer arms and legs for the same reason\u2014to be able to cover more ground, more efficiently. This means that having long legs is an analogous trait in baboons and humans: \u2014that is, this adaptation evolved independently in the two species but for the same purpose. Using homology and analogy, our closest living relatives provide the critical context in which to understand human biology, morphology, and behaviour. It is only by studying how humans compare with our primate relatives that we can fully comprehend our place in nature.<\/p>\n<h3 class=\"import-Normal\"><strong>Ways of Organizing Taxa<\/strong><\/h3>\n<p class=\"import-Normal\">You learned in Chapter 2 about Linnaeus and the hierarchical nature of taxonomic classification. Our goal in classifying taxa is to create categories that reflect clade relationships. A <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1116\">clade<\/a> <\/strong>is a grouping of organisms based on relatedness that reflects a branch of the evolutionary tree. Clade relationships are determined using traits shared by groups of taxa as well as genetic similarities. An example of a clade would be a grouping that includes humans, chimpanzees, bonobos, and gorillas (Figure 6.1). These taxa are in what is referred to as the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1118\">African clade<\/a><\/strong> of hominoids (a taxonomic group you will learn about later in this chapter). The African clade grouping reflects how humans, chimpanzees, bonobos, and gorillas all share a more recent ancestor with each other than any of them do with other species\u2014that is, we are on the same branch of the evolutionary tree. We know members of the African clade are most closely related based on shared morphological traits as well as genetic similarities. Excluded from this grouping is the orangutan, which is considered a member of the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1120\">Asian clade<\/a><\/strong> of hominoids.<\/p>\n<figure style=\"width: 800px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2023\/06\/image1-3.jpg\" alt=\"Diagram shows large-bodied hominoids grouped by grade or clade.\" width=\"800\" height=\"358\" \/><figcaption class=\"wp-caption-text\">Figure 6.1: Grades vs. Clades. A grade grouping of apes places orangutans, gorillas, chimpanzees, and bonobos together based on their similar appearance and lifestyle, but excludes humans. Clade classification is based on shared derived traits and genetic evidence (both reflecting close evolutionary relationships). A clade grouping of apes places humans with gorillas, chimpanzees, and bonobos., whereas orangutans are separated. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\">Grades vs. clades comparison (Figure 5.12)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\">CC BY-NC-SA 4.0 License<\/a>. [Includes <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Orangutan_on_a_tree_(Unsplash).jpg\">Orangutan on a tree (Unsplash)<\/a> by Dawn Armfield, <a href=\"https:\/\/creativecommons.org\/publicdomain\/zero\/1.0\/legalcode\">public domain (CC0 1.0)<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Gorilla_Profile_(17997840570).jpg\">Gorilla Profile (17997840570)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/100915417@N07\">Charlie Marshall<\/a> from Bristol UK, modified (cropped), <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/legalcode\">CC BY 2.0 License<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Chimpanzee_(14679767561).jpg\">Chimpanzee (14679767561)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/120374925@N06\">Magnus Johansson<\/a>, modified (cropped), <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\">CC BY-SA 2.0<\/a>; <a href=\"https:\/\/pixabay.com\/photos\/pointing-finger-hand-pointing-1922074\/\">Pointing finger (1922074)<\/a> by <a href=\"https:\/\/pixabay.com\/users\/truthseeker08-2411480\/\">truthseeker08<\/a>, <a href=\"https:\/\/pixabay.com\/service\/terms\/#license\">Pixabay License<\/a>.]<\/figcaption><\/figure>\n<p class=\"import-Normal\">In contrast, <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1122\">grades<\/a> <\/strong>are groupings that reflect levels of adaptation or overall similarity and not necessarily evolutionary relationships. An example of a grade would be placing orangutans, gorillas, bonobos, and chimpanzees into a group, and excluding humans. Grouping in this way is based on the superficial similarities of the apes in being large-bodied, having lots of body hair, living in tropical forests, climbing and sleeping in trees, and so on. According to these criteria, humans seem to be unusual in that we differ in our morphology, behaviour, and ecology. Separating humans from the large-bodied apes is the system that was used historically. We now know that grouping orangutans, gorillas, bonobos, and chimpanzees and excluding humans does not accurately reflect our true evolutionary relationships. Since our goal in taxonomic classification is to organize animals to reflect their evolutionary relationships, we prefer to use clade classifications.<\/p>\n<h3 class=\"import-Normal\"><strong>Types of Traits<\/strong><\/h3>\n<p class=\"import-Normal\">When evaluating relationships between taxa, we use key traits that allow us to determine which species are most closely related to one another. Traits can be either ancestral or derived. <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1124\">Ancestral traits<\/a><\/strong> are those that a taxon has because it has inherited the trait from a distant ancestor. For example, all primates have body hair because we are mammals and all mammals share an ancestor hundreds of millions of years ago that had body hair. This trait has been passed down to all mammals from a shared ancestor, so all mammals alive today have body hair. <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1126\">Derived traits<\/a><\/strong> are those that have been more recently altered. This type of trait is most useful when we are trying to distinguish one group from another because derived traits tell us which taxa are more closely related to each other. For example, humans walk on two legs.The many adaptations that humans possess that allow us to move in this way evolved after humans split from the Genus <em>Pan<\/em>. This means that when we find fossil taxa that share derived traits for walking on two legs, we can conclude that they are likely more closely related to humans than to chimpanzees and bonobos<em>. <\/em><\/p>\n<p class=\"import-Normal\">There are a couple of other important points about ancestral and derived traits that will become apparent as we discuss primate diversity. First, the terms <em>ancestral<\/em> and <em>derived<\/em> are relative terms, meaning that a trait can be either one depending on the taxa being compared. For example, in the previous paragraph, body hair was used as an example for an ancestral trait among primates. All mammals have body hair because we share a distant ancestor who had this trait. The presence of body hair therefore doesn\u2019t allow you to distinguish whether monkeys are more closely related to apes or lemurs because they all share this trait. However, if we are comparing mammals to birds and fish, then body hair becomes a derived trait of mammals. It evolved after mammals diverged from birds and fish, and it tells us that all mammals are more closely related to each other than they are to birds or fish.The second important point is that very often when one lineage splits into two, one taxon will stay more similar to the last common ancestor in retaining more ancestral traits, whereas the other lineage will usually become more different from the last common ancestor by developing more derived traits. This will become very apparent when we discuss the two suborders of primates, Strepsirrhini and Haplorrhini. When these two lineages diverged, strepsirrhines retained more ancestral traits (those present in the earliest primates) and haplorrhines developed more derived traits (became more different from ancestral primates).<\/p>\n<p class=\"import-Normal\">There are two other types of traits that will be relevant to our discussions here: generalized and specialized traits. <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1128\">Generalized traits<\/a> <\/strong>are those characteristics that are useful for a wide range of things. Having <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1138\">opposable thumbs<\/a><\/strong> that go in a different direction than the rest of your fingers is a very useful, generalized trait. You can hold a pen, grab a branch, peel a banana, or text your friends all thanks to your opposable thumbs! <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1130\">Specialized traits<\/a> <\/strong>are those that have been modified for a specific purpose. These traits may not have a wide range of uses, but they will be very efficient at their job. Hooves in horses are a good example of a specialized trait: they allow horses to run quickly on the ground on all fours. You can think of generalized traits as a Swiss Army knife, useful for a wide range of tasks but not particularly good at any one of them. That is, if you\u2019re in a bind, then a Swiss Army knife can be very useful to cut a rope or fix a loose screw, but if you were going to build furniture or fix a kitchen sink, then you\u2019d want specialized tools for the job. As we will see, most primate traits tend to be generalized.<\/p>\n<h2 class=\"import-Normal\">What Makes Something a Primate?<\/h2>\n<p class=\"import-Normal\">The Order Primates is distinguished from other groups of mammals in having a <em>suite of characteristics<\/em>. This means that there is no individual trait that you can use to instantly identify an animal as a primate; instead, you have to look for animals that possess a collection of traits. What this also means is that each individual trait we discuss may be found in nonprimates, but if you see an animal that has most or all of these traits, there is a good chance it is a primate.<\/p>\n<p class=\"import-Normal\">Primates are most distinguishable from other organisms in traits related to our vision. Our Order relies on vision as a primary sense, which is reflected in many areas of our anatomy and behaviour. All primates have eyes that face forward with convergent (overlapping) visual fields. So if you cover one eye with your hand, you can still see most of the room with your other one. This also means that we cannot see on the sides or behind us as well as some other animals can. In order to protect the sides of the eyes from the muscles we use for chewing, all primates have at least a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1132\">postorbital bar<\/a>, <\/strong>a bony ring around the outside of the eye (Figure 6.2). Primate taxa with more convergent eyes need extra protection, so animals with greater orbital convergence will have a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1134\">postorbital plate<\/a> <\/strong>or<strong> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1136\">postorbital closure<\/a> <\/strong>in addition to the bar (Figure 6.2).The postorbital bar is a derived trait of primates, appearing in our earliest ancestors.<\/p>\n<figure style=\"width: 661px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image2-4.jpg\" alt=\"Skulls of a monkey and lemur viewed from the side and top.\" width=\"661\" height=\"430\" \/><figcaption class=\"wp-caption-text\">Figure 6.2: All primates have bony protection around their eyes. Some have a postorbital bar only (right), but many have full postorbital closure, also called a postorbital plate, that completely protects the back of the eye socket (left). Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\">Postorbital bar\/Postorbital closure (Figure 5.1)<\/a> a derivative work original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\">CC BY-NC-SA 4.0 License<\/a>. [Includes <a href=\"https:\/\/animaldiversity.org\/accounts\/Otolemur_crassicaudatus\/specimens\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Otolemur_crassicaudatus\/lateral\/\">Otolemur crassicaudatus (greater galago)<\/a> by <a href=\"https:\/\/animaldiversity.org\/\">Animal Diversity Web<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\">CC BY-NC-SA 3.0<\/a>; <a href=\"https:\/\/animaldiversity.org\/accounts\/Otolemur_crassicaudatus\/specimens\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Otolemur_crassicaudatus\/dorsal1809\/\">Macaca fascicularis (long-tailed macaque)<\/a> by <a href=\"https:\/\/animaldiversity.org\/\">Animal Diversity Web<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\">CC BY-NC-SA 3.0<\/a>.]<\/figcaption><\/figure>\n<p class=\"import-Normal\">Another distinctive trait of our Order is that many primates have <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1140\">trichromatic color vision<\/a><\/strong>, the ability to distinguish reds and yellows in addition to blues and greens. Birds, fish, and reptiles are <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1142\">tetrachromatic<\/a> <\/strong>(they can see reds, yellows, blues, greens, and even ultraviolet), but most mammals, including some primates, are only <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1144\">dichromatic<\/a> <\/strong>(they see only in blues and greens). It is thought that the nocturnal ancestors of mammals benefited from seeing better at night rather than in colour, and so dichromacy is the ancestral condition for mammals. Trichromatic primates are known to use their colour vision for all sorts of purposes: finding young leaves and ripe fruits, identifying other species, and evaluating signals of health and fertility.<\/p>\n<p class=\"import-Normal\">The primate visual system uses a lot of energy, so primates have compensated by cutting back on other sensory systems, particularly our sense of smell. Compared to other mammals, primates have reduced snouts, another derived trait that appears even in the earliest primate ancestors. There is variation across primate taxa in how much snouts are reduced. Those with a better sense of smell usually have poorer vision than those with a relatively dull sense of smell. The reason for this is that all organisms have a limited amount of energy to spend on running our bodies, so we make <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1146\">evolutionary trade-offs<\/a><\/strong>, as energy spent on one trait cuts back on energy spent on another. So primates with better vision are spending more energy on vision and thus have a poorer smell (and shorter snout), and those who spend less energy on vision will have a better sense of smell (and a longer snout).<\/p>\n<p class=\"import-Normal\">Primates also differ from other mammals in the size and complexity of our brains. On average, primates have brains that are twice as big for their body size when compared to other mammals. Not unexpectedly, the visual centres of the brain are larger in primates and the wiring is different from that in other animals, reflecting our reliance on this sense. The neocortex, which is used for higher functions like consciousness and language in humans, as well as sensory perception and spatial awareness, is also larger in primates relative to other animals. In nonprimates this part of the brain is often smooth, but in primates it is made up of many folds, which increase the surface area. It has been proposed that the more complex neocortex of primates is related to diet, with fruit-eating primates having larger relative brain sizes than leaf-eating primates, due to the more challenging cognitive demands required to find and process fruits (Clutton-Brock &amp; Harvey 1980). An alternative hypothesis argues that larger brain size is necessary for navigating the complexities of primate social life, with larger brains occurring in species who live in bigger, more complex groups relative to those living in pairs or solitarily (Dunbar 1998). There seems to be support for both hypotheses, as large brains are a benefit under both sets of selective pressures.<\/p>\n<p class=\"import-Normal\">Animals with large brains usually have extended life history patterns, and primates are no exception. <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1148\">Life history<\/a> <\/strong>refers to the pace at which an organism grows, reproduces, and ages. Some animals grow very quickly and reproduce many offspring in a short time frame but do not live very long. Other animals grow slowly, reproduce few offspring, reproduce infrequently, and live a long time. Primates are all in the \u201cslow lane\u201d of life history patterns. Compared to animals of similar body size, primates grow and develop more slowly, have fewer offspring per pregnancy, reproduce less often, and live longer. Primates also invest heavily in each offspring. With a few exceptions, most primates only have one offspring at a time. A group of small-bodied monkeys in South America regularly give birth to twins, and some lemurs can give birth to multiple offspring at a time, but these primates are the exception rather than the rule. Primates also reproduce relatively infrequently. The fastest-reproducing primates will produce offspring about every six months, while the slowest, the orangutan, reproduces only once every seven to nine years. This very slow reproductive rate makes the orangutan the slowest-reproducing animal on the planet! Primates are also characterized by having long lifespans. The group that includes humans and large-bodied apes has the most extended life history patterns among all primates, with some large-bodied apes estimated to live up to 58 years in the wild (Robson Et al. 2006).<\/p>\n<figure style=\"width: 392px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image3-5.jpg\" alt=\"Various hands and feet of different primate species.\" width=\"392\" height=\"624\" \/><figcaption class=\"wp-caption-text\">Figure 6.3: These drawings of the hands and feet of different primates show the opposable thumbs and big toes, pentadactyly, flattened nails, and tactile pads characteristic of our Order. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:PrimateFeet.jpg\">PrimateFeet<\/a> by <a href=\"https:\/\/en.wikipedia.org\/wiki\/Richard_Lydekker\">Richard Lydekker<\/a>, original from The Royal Natural History 1:15 (1893), is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\">public domain<\/a>.<\/figcaption><\/figure>\n<p>Primates also differ from other animals in our hands and feet. The Order Primates is a largely <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1150\">arboreal<\/a><\/strong> taxonomic group, meaning that most primates spend a significant amount of their time in trees. As a result, the hands and feet of primates have evolved to move in a three-dimensional environment. Primates have the generalized trait of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1152\">pentadactyly<\/a><\/strong>\u2014 possessing five digits (fingers and toes) on each limb. Many nonprimates, like dogs and horses, have fewer digits because they are specialized for high-speed, <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1154\">terrestrial<\/a><\/strong> (on the ground) running. Pentadactyly is also an ancestral trait, one that dates back to the earliest four-footed animals. Primates today have opposable thumbs and, with the exception of humans, opposable big toes (Figure 6.3). Opposable thumbs and toes are a derived trait that appeared in the earliest primate fossils about 55 million years ago. Having thumbs and big toes that go in a different direction from the rest of the fingers and toes allow primates to be excellent climbers in trees as well as to manipulate objects. Our ability to manipulate objects is further enhanced by the flattened nails on the backs of our fingers and toes that we possess in the place of the claws and hooves that many other mammals have. On the other side of our digits, we have sensitive <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1156\">tactile pads<\/a> <\/strong>that allow us to have a fine sense of touch. Primates use this fine sense of touch for handling food and, in many species, grooming themselves and others. In primates, grooming is an important social currency, through which individuals forge and maintain social bonds.<\/p>\n<table class=\"alignright\" style=\"width: 219.75pt;height: 407px\">\n<caption>Figure 6.4: Primate Traits at a Glance: This table summarizes the suite of traits that differentiate primates from other mammals. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\">Primate at a glance table (Figure 5.3)<\/a> by Stephanie Etting original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/caption>\n<thead>\n<tr style=\"height: 30px\">\n<td class=\"a-C\" style=\"background-color: transparent;padding: 5pt;border: 1pt solid #000000;height: 30px;width: 361.667px\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Primate suite of traits<\/strong><\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"a-R\" style=\"height: 362px\">\n<td class=\"a-C\" style=\"background-color: transparent;padding: 5pt;border: 1pt solid #000000;height: 362px;width: 361.667px\">\n<p class=\"import-Normal\" style=\"text-align: center\">Convergent eyes<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Postorbital bar<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Many have trichromatic colour vision<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Short snouts<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Opposable thumbs and big toes<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Pentadactyly<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Flattened nails<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Tactile pads<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Highly arboreal<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Large brains<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Extended life histories<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Live in the tropics<\/p>\n<\/td>\n<\/tr>\n<tr style=\"height: 15px\">\n<td style=\"height: 15px;width: 362.033px\"><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>Lastly, primates are very social animals. All primates, even those that search for food alone, establish strong social networks within species. Unlike many animals, primates do not migrate: they stay in a relatively stable area for their whole life, often interacting with the same individuals for their long lives. The long-term relationships that primates form with others of their species lead to complex and fascinating social behaviours (see Chapter 7). Finally, nonhuman primates show a clear preference for tropical regions of the world. Most primates are found between the Tropic of Cancer and the Tropic of Capricorn, with only a few taxa living outside these regions. Figure 6.4 shows a summary of primate traits.<\/p>\n<h2 class=\"import-Normal\">Key Traits Used to Distinguish Between Primate Taxa<\/h2>\n<p class=\"import-Normal\">When placing primate species into specific taxonomic groups, we focus on dental characteristics, behavioural adaptations, and locomotor adaptations. Differences in these characteristics across groups reflect constraints of evolutionary history as well as variation in adaptations.<\/p>\n<h3 class=\"import-Normal\"><strong>Dental Characteristics<\/strong><\/h3>\n<p class=\"import-Normal\">Teeth may not seem like the most exciting topic with which to start, but we can learn a tremendous amount about an organism from its teeth. First, teeth are vital to survival. Wild animals do not have the benefit of knives and forks; they rely on their teeth to process their food. Because of this, teeth of any species have evolved to reflect what that organism eats and therefore have a lot to tell us about their diet. Second, variation in tooth size, shape, and number reveals an organism\u2019s evolutionary history. Some taxa have more teeth than others or different forms of teeth. Furthermore, differences in teeth between males and females can tell us about competition over mates (see Chapter 7). Lastly, teeth are overly represented in the fossil record. Enamel is hard, and there is little meat on jaws so carnivores and scavengers often leave them behind. Sometimes, the only remains we have from an extinct taxon is its teeth!<\/p>\n<figure style=\"width: 356px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image4-4-1.jpg\" alt=\"Yawning baboon with large teeth.\" width=\"356\" height=\"266\" \/><figcaption class=\"wp-caption-text\">Figure 6.5: This picture of an open-mouthed Hamadryas baboon demonstrates the diastema between his upper canine and front teeth. This space is taken up by his lower canine when he closes his mouth. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Ha,ha,ha_...._(14986571843).jpg\">Ha,ha,ha .... (14986571843)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/104249543@N07\">Rolf Dietrich Brecher<\/a> from Germany is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\">CC BY-SA 2.0 License<\/a>.<\/figcaption><\/figure>\n<p>Like other mammals, primates are <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1158\">heterodont<\/a><\/strong>: they have multiple types of teeth that are used for different purposes. We have <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1160\">incisors<\/a> <\/strong>for slicing; <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1162\">premolars<\/a> <\/strong>and <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1164\">molars<\/a> <\/strong>for grinding up our food; and <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1166\">canines<\/a><\/strong>, which most primates (not humans) use as weapons against predators and each other. The sizes of canines vary across species and can often be <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1168\">sexually dimorphic<\/a><\/strong>, with males tending to have larger canines than females. Some nonhuman primates <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1170\">hone<\/a><\/strong>, or sharpen, their canines by gnashing the teeth together to sharpen the sides. The upper canine sharpens on the first lower premolar and the lower canine sharpens on the front of the upper canine. As canines get larger, they require a space to fit in order for the jaws to close. This space between the teeth is called a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1172\">diastema<\/a><\/strong> (Figure 6.5).<\/p>\n<p class=\"import-Normal\">We use a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1174\">dental formula<\/a><\/strong> to specify how many incisors, canines, premolars, and molars are in each quadrant of the mouth (half of the top or bottom). For example, Figure 6.6 shows half of the lower teeth of a human. You can see that in half of the mandible, there are two incisors, one canine, two premolars, and three molars. This dental formula is written as 2:1:2:3. (The first number represents the number of incisors, followed by the number of canines, premolars, and molars.)<\/p>\n<figure style=\"width: 241px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image5-5.png\" alt=\"Human mandible with four types of teeth.\" width=\"241\" height=\"424\" \/><figcaption class=\"wp-caption-text\">Figure 6.6:\u00a0 This drawing shows half of the human mandible. With the four types of teeth labeled, you can determine that the dental formula is 2:1:2:3. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Gray997.png\">Gray997<\/a> by <a href=\"https:\/\/en.wikipedia.org\/wiki\/Henry_Vandyke_Carter\">Henry Vandyke Carter<\/a>, original in Henry Gray (1918) Anatomy of the Human Body, Plate 997, is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\">public domain<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">To determine the dental formula, you need to be able to identify the different types of teeth. You can recognize incisors because they often look like spatulas with a flat, blade-like surface. Premolars and molars can be differentiated by the number of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1176\">cusps<\/a><\/strong> that they have. Cusps are the bumps that you can feel with your tongue on the surface of your back teeth. Premolars are smaller than molars and, in primates, often have one or two cusps on them. Molars are bigger, providing a larger chewing surface, and have more cusps. Depending on the species and whether you\u2019re looking at upper or lower teeth, primate molars can have between three and five cusps. Molar cusps can also vary between taxa in how they are arranged; you will learn more about this later in this chapter. Canines are often easy to distinguish because, in most taxa, they are much longer and more conical than the other teeth.<\/p>\n<p class=\"import-Normal\">Teeth also directly reflect an organism\u2019s diet. Primates are known to eat a wide range of plant parts, insects, gums, and, rarely, meat. While all primates eat a variety of foods, what differs among primates are the proportions of each of these food items in the diet. That is, two primates living in the same forest may be eating the same foods but in vastly different proportions, and so we would categorize them as different dietary types. The most common dietary types among primates are those whose diets consist primarily of fruit (<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_954\">frugivores<\/a><\/strong>), those who eat mostly insects (<strong>insectivores<\/strong>), and those who eat primarily leaves (<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_956\">folivores<\/a><\/strong>). A few primate taxa are <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1178\">gummivores<\/a><\/strong>, specializing in eating gums and saps, but we will only focus on the adaptations found in the three primary dietary groups.<\/p>\n<h4 class=\"import-Normal\"><em>Frugivores<\/em><\/h4>\n<p class=\"import-Normal\">Plants want animals to eat their fruits because, in doing so, animals eat the seeds of the fruit and then disperse them far away from the parent plant. Therefore, plants often \u201cadvertise\u201d fruits by making them colourful and easy to spot, full of easy-to-digest sugars that make them taste good and, often, easy to chew and digest (not being too fibrous or tough). For these reasons, frugivores often do not need a lot of specialized traits to consume a diet rich in fruits (Figure 6.7). Their molars usually have a broad chewing surface with low, rounded cusps (referred to as <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1180\">bunodont<\/a> <\/strong>molars). Frugivores have large incisors for slicing through the outer coatings on fruit, and they tend to have stomachs, colons, and small intestines that are intermediate in terms of size and complexity between insectivores and folivores (Chivers &amp; Hladik 1980). They are also usually of intermediate body size between the other two dietary types. Because fruit does not contain protein, frugivores must supplement their diet with protein from insects, leaves, and\/or seeds. Frugivores who get protein by eating seeds evolved to have thicker enamel on their teeth to protect them from excessive wear.<\/p>\n<figure style=\"width: 503px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image6-2.jpg\" alt=\"Upper teeth and maxilla of a frugivore monkey.\" width=\"503\" height=\"331\" \/><figcaption class=\"wp-caption-text\">Figure 6.7: Frugivores are characterized by large incisors, bunodont molars, and digestive tracts that are intermediate in complexity between the other two dietary types. Credit: <a href=\"https:\/\/animaldiversity.org\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Papio_papio\/utr0087\/\">Papio papio (Guinea baboon).jpg<\/a> by Phil Myers on <a href=\"https:\/\/animaldiversity.org\">Animal Diversity Web<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\">CC BY-NC-SA 3.0 License. <\/a><\/figcaption><\/figure>\n<h4 class=\"import-Normal\"><em>Insectivores<\/em><\/h4>\n<p class=\"import-Normal\">While insects can be difficult to find and catch, they are easy to chew and digest. As a result, insectivorous primates usually have small molars with pointed cusps to puncture the exoskeleton of the insects (Figure 6.8), and they have simple stomachs and colons with a long small intestine to process the insects. Nutritionally, insects provide a lot of protein and fat but are not plentiful enough in the environment to support large-bodied animals, so insectivores are usually the smallest of the primates.<\/p>\n<figure style=\"width: 351px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image7-3.jpg\" alt=\"Mandible, upper teeth, and maxilla of insectivore tarsier.\" width=\"351\" height=\"280\" \/><figcaption class=\"wp-caption-text\">Figure 6.8: Insectivores need sharp, pointed molar cusps to break through the exoskeletons of insects. Insects are easy to digest, so these primates have simple digestive tracts. Credit: Tarsier (an insectivor)\u2019s teeth original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Stephanie Etting is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\">CC BY-NC-SA 3.0 License.<\/a> [Includes <a href=\"https:\/\/animaldiversity.org\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Tarsius_syrichta\/lower_lateral1942\/\">Lower_lateral1942<\/a> by Phil Myers on <a href=\"https:\/\/animaldiversity.org\">Animal Diversity Web<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\">CC BY-NC-SA 3.0<\/a>; <a href=\"https:\/\/animaldiversity.org\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Tarsius_syrichta\/ventral\/\">Ventral<\/a> by Phil Myers on <a href=\"https:\/\/animaldiversity.org\">Animal Diversity Web<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\">CC BY-NC-SA 3.0<\/a>.]<\/figcaption><\/figure>\n<h4 class=\"import-Normal\"><em>Folivores<\/em><\/h4>\n<p class=\"import-Normal\">Plants rely on leaves to get energy from the sun, so plants do not want animals to eat their leaves (unlike their fruit). As a result, plants evolved to try to discourage animals from eating their leaves. Leaves often carry toxins, taste bitter, are very fibrous and difficult to chew, and are made of large cellulose molecules that are difficult to break down into usable sugars. Thus, animals who eat leaves need a lot of specialized traits (Figure 6.9). Folivorous primates have broad molars with high, sharp cusps connected by <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1182\">shearing crests<\/a><\/strong>. These molar traits allow folivores to physically break down fibrous leaves when chewing. Folivores then chemically break down cellulose molecules into usable energy. To do this, some folivores have complex stomachs with multiple compartments, while others have large, long intestines and special gut bacteria that can break up cellulose. Folivores are usually the largest bodied of all primates, and they tend to spend a large portion of their day digesting their food, so they are less active than frugivores or insectivores.<\/p>\n<figure style=\"width: 468px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image8-2.jpg\" alt=\"Upper teeth and maxilla of a monkey shows folivore traits.\" width=\"468\" height=\"337\" \/><figcaption class=\"wp-caption-text\">Figure 6.9: To derive energy from leaves, folivores, like this Trachypithecus (dusky leaf monkey), have smaller incisors and high sharp molar cusps connected by shearing crests. Credit: <a href=\"https:\/\/animaldiversity.org\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Trachypithecus_obscurus\/utr0075\/\">Trachypithecus obscurus (dusky leaf monkey) upper teeth<\/a> by Phil Myers on <a href=\"https:\/\/animaldiversity.org\">Animal Diversity Web<\/a> has been modified (background removed, labels added by Stephanie Etting) is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\">CC BY-NC-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<h3 class=\"import-Normal\"><strong>Behavioural Adaptations<\/strong><\/h3>\n<p class=\"import-Normal\">Since Chapter 6 is dedicated to primate behaviour, we will only briefly discuss variations in activity patterns, social grouping, and habitat use. Primate groups differ in <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1184\">activity patterns<\/a><\/strong>: whether they are active during the day (<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1012\">diurnal<\/a><\/strong>), at night (<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1010\">nocturnal<\/a><\/strong>), or through the 24-hour period (<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1186\">cathemeral<\/a><\/strong>). Primate taxa vary in social groupings: some are primarily solitary, others live in pairs, and still others live in groups of varying sizes and compositions. Lastly, some taxa are primarily arboreal while others are more terrestrial.<\/p>\n<h3 class=\"import-Normal\"><strong>Locomotor Adaptations<\/strong><\/h3>\n<p class=\"import-Normal\">Finally, primate groups vary in their adaptations for different forms of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1188\">locomotion<\/a><\/strong>, or how they move around. Living primates are known to move by vertical clinging and leaping, quadrupedalism, brachiation, and bipedalism.<\/p>\n<p class=\"import-Normal\"><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1190\">Vertical clinging and leaping<\/a> <\/strong>is when an animal grasps a vertical branch with its body upright, pushes off with long hind legs, and then lands on another vertical support branch (Figure 6.10a). Animals who move in this way usually have longer legs than arms, long fingers and toes, and smaller bodies. Vertical clinger leapers also tend to have elongated ankle bones, which serve as a lever to help them push off with their legs and leap to another branch (Figure 6.10b).<\/p>\n<p>&lt;!-- marker for original place of <\/p><\/div>\n<\/p><\/div>\n<p> --&gt;<\/p>\n<figure id=\"attachment_181-6\" aria-describedby=\"caption-attachment-181-6\" style=\"width: 608px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-147\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/5.10.jpg\" alt=\"Movement of vertical clinger and leaper, and tarsier skeleton.\" width=\"608\" height=\"462\" \/><figcaption id=\"caption-attachment-181-6\" class=\"wp-caption-text\">Figure 6.10a: Vertical clingers and leapers have longer legs than arms, long lower backs, and long fingers and toes. They also have elongated ankle bones to help them push off when leaping. Credit: a. <a href=\"https:\/\/upload.wikimedia.org\/wikipedia\/commons\/6\/6e\/Propithecus_vertical_clinging_and_leaping.svg\">Propithecus vertical clinging and leaping<\/a> by Terpsichores is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/\"> CC BY-SA 3.0 License<\/a>. 6.10b: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Em_-_Tarsius_tarsier_-_3.jpg\">Tarsier skeleton<\/a> by Em\u0151ke D\u00e9nes has been modified (background removed) by Stephanie Etting and is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/\">CC BY-SA 4.0 License<\/a>. Original Spectral tarsier (Tarsius tarsier) skeleton at the Cambridge University Museum of Zoology, England.)<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<div class=\"learning-objectives\">\n<p class=\"import-Normal\"><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1192\">Quadrupedalism<\/a><\/strong>, walking on all fours, is the most common form of locomotion among primates. Quadrupedal animals usually have legs and arms that are about the same length and a tail for balance. Arboreal quadrupeds (Figure 6.11a) usually have shorter arms and legs and longer tails, while terrestrial quadrupeds (Figure 6.11b) have longer arms and legs and, often, shorter tails. These differences relate to the lower centre of gravity needed by arboreal quadrupeds for balance in trees and the longer tail required for better balance when moving along the tops of branches. Terrestrial quadrupeds have longer limbs to help them cover more distance more efficiently.<\/p>\n<\/div>\n<figure id=\"attachment_181-7\" aria-describedby=\"caption-attachment-181-7\" style=\"width: 704px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-148\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/5.11.jpg\" alt=\"Arboreal quadrupedal monkey and terrestrial quadrupedal monkey.\" width=\"704\" height=\"251\" \/><figcaption id=\"caption-attachment-181-7\" class=\"wp-caption-text\">Figure 6.11a\/b: Two examples of quadrupedal primates. The capuchin monkey skeleton on the left (a) is a typical arboreal quadruped with shorter arms and legs, longer fingers and toes, and a long tail. The baboon skeleton on the right (b) is a terrestrial quadruped with relatively long arms and legs, shorter fingers and toes, and a short tail. Credits: 6.11a. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Description_iconographique_compar%C3%A9e_du_squelette_et_du_syst%C3%A8me_dentaire_des_mammif%C3%A8res_r%C3%A9cents_et_fossiles_(Sapajus_apella).jpg\">Capuchin monkey skeleton<\/a> by Henri-Marie Ducrotay de Blainville is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\">public domain<\/a>. 6.11b. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Description_iconographique_compar%C3%A9e_du_squelette_et_du_syst%C3%A8me_dentaire_des_mammif%C3%A8res_r%C3%A9cents_et_fossiles_(Papio_ursinus).jpg\">Baboon<\/a> by Henri-Marie Ducrotay de Blainville is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\">public domain<\/a>.<\/figcaption><\/figure>\n<div class=\"learning-objectives\">\n<p class=\"import-Normal\">The third form of locomotion seen in primates is<strong> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1194\">brachiation<\/a><\/strong>, the way of moving you used if you played on \u201cmonkey bars\u201d as a child. Brachiation involves swinging below branches by the hands (Figure 6.12a). To be an efficient brachiator, a primate needs to have longer arms than legs, flexible shoulders and wrists, a short lower back, and no tail (Figure 6.12b). Some primates move via <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1196\">semi-brachiation<\/a><\/strong>, in which they swing below branches but do not have all of the same specializations as brachiators. Semi-brachiators have flexible shoulders, but their arms and legs are about the same length, which is useful because they are quadrupedal when on the ground. They also use long <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1198\">prehensile tails<\/a><\/strong> as a third limb when swinging (Figure 6.13). The underside of the tail has a tactile pad, resembling your fingerprints, for better grip.<\/p>\n<\/div>\n<figure id=\"attachment_181-8\" aria-describedby=\"caption-attachment-181-8\" style=\"width: 1600px\" class=\"wp-caption alignnone\"><img class=\"wp-image-149 size-full\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/5.12.jpg\" alt=\"Primate swinging through branches and gibbon skeleton.\" width=\"1600\" height=\"800\" \/><figcaption id=\"caption-attachment-181-8\" class=\"wp-caption-text\">Figure 6.12a. Example of brachiation. 6.12b. Skeleton of a typical brachiator, showing longer arms than legs, short back, and lack of a tail. Credit: a. <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\">Brachiator (Figure 5.9b)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>. b. <a href=\"https:\/\/upload.wikimedia.org\/wikipedia\/commons\/a\/a3\/Giboia.jpg\">Skeleton of Gibbon (Giboia) <\/a>by Joxerra Aihartza is under a <a href=\"https:\/\/artlibre.org\">Free Art License<\/a>.<\/figcaption><\/figure>\n<div class=\"learning-objectives\">\n<figure style=\"width: 565px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image15-1.jpg\" alt=\"Spider monkey swinging below a rope.\" width=\"565\" height=\"377\" \/><figcaption class=\"wp-caption-text\">Figure 6.13. Spider monkeys are considered semi-brachiators, as they can swing below branches but use their tails as a third limb. On the ground they move via quadrupedal locomotion. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Ateles-fusciceps_54724770b.jpg\">Ateles-fusciceps 54724770b<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:LeaMaimone\">LeaMaimone<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.5\/legalcode\">CC BY 2.5 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Lastly, humans move around on two feet, called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1200\">bipedalism<\/a><\/strong>. Some nonhuman primates will occasionally travel on two feet but do so awkwardly and never for long distances. Among mammals, only humans have evolved to walk with a striding gait on two legs as a primary form of locomotion.<\/p>\n<h2 class=\"import-Normal\">Primate Diversity<\/h2>\n<p class=\"import-Normal\">As we begin exploring the different taxa of primates, it is important to keep in mind the hierarchical nature of taxonomic classification and how this relates to the key characteristics that will be covered. Figure 6.14 summarizes the major taxonomic groups of primates that you will learn about here. If you locate humans on the chart, you can trace our classification and see all of the categories getting more inclusive as you work your way up to the Order Primates. This means that humans will have the key traits of each of those groups. It is a good idea to refer to the figure to orient yourself as we discuss each taxon.<\/p>\n<figure style=\"width: 2048px\" class=\"wp-caption alignnone\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image16-1.jpg\" alt=\"Taxonomic chart shows primate order, suborder, infraorder, superfamily, and species.\" width=\"2048\" height=\"1154\" \/><figcaption class=\"wp-caption-text\">Figure 6.14: This taxonomy chart shows the major groups of primate taxa, starting with the largest category (Order) and moving to more specific categories and examples. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\">A full text description of this image is available<\/a>. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\">Primate taxonomy char (Figure 5.11)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/\">CC BY-NC 4.0 License<\/a>. [Includes <a href=\"https:\/\/phylopic.org\/image\/d6cfb28f-136e-4a20-a5ac-8eb353c7fc4a\/\">Lemur catta Linnaeus, 1759<\/a> by Roberto D\u00edaz Sibaja, <a href=\"https:\/\/creativecommons.org\/licenses\/by\/3.0\/\">CC BY 3.0<\/a>; <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\">Lorisoidea<\/a> original to<a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\"> Explorations: An Open Invitation to Biological Anthropology<\/a> by Katie Nelson, <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0<\/a>; <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\">Tarsiiformes<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson, <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0<\/a>; <a href=\"https:\/\/phylopic.org\/image\/156b515d-f25c-4497-b15b-5afb832cc70c\/\">Cebinae Bonaparte, 1831<\/a> by Sarah Werning, <a href=\"https:\/\/creativecommons.org\/licenses\/by\/3.0\/\">CC BY 3.0<\/a>; <a href=\"https:\/\/phylopic.org\/image\/899742c2-9a40-4fa0-b2cd-2eb133c8f6e8\/\">Colobus guereza Ruppell, 1835<\/a> by Yan Wong, designated to the <a href=\"https:\/\/creativecommons.org\/publicdomain\/zero\/1.0\/\">public domain (CC0)<\/a>; <a href=\"https:\/\/phylopic.org\/image\/72f2f854-f3cd-4666-887c-35d5c256ab0f\/\">Papio cynocephalus<\/a> by Owen Jones, designated to the <a href=\"https:\/\/creativecommons.org\/publicdomain\/zero\/1.0\/\">public domain (CC0)<\/a>; <a href=\"https:\/\/pixabay.com\/vectors\/animals-silhouette-wolf-elephant-2755766\/\">animals silhouette wolf elephant (2755766)<\/a> by <a href=\"https:\/\/pixabay.com\/users\/mohamed_hassan-5229782\/\">mohamed_hassan<\/a>, <a href=\"https:\/\/pixabay.com\/service\/terms\/#license\">Pixabay License<\/a>.]<\/figcaption><\/figure>\n<h3 class=\"import-Normal\"><strong>Suborder Strepsirrhini<\/strong><\/h3>\n<figure style=\"width: 387px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image17-1.jpg\" alt=\"Eight strepsirrhine species.\" width=\"387\" height=\"605\" \/><figcaption class=\"wp-caption-text\">Figure 6.15: (Clockwise from top right) sifaka, black-and-white ruffed lemur, loris, galago, slender loris, mouse lemur, aye-aye, and ring-tailed lemur. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Extant_Strepsirrhini.jpg\">Extant Strepsirrhini<\/a> a collective work by <a href=\"https:\/\/www.flickr.com\/people\/23661161@N02\">Mark Dumont<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\">CC BY-SA 3.0 License<\/a>. [Includes <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Katta_csal%C3%A1d.jpg\">Katta csal\u00e1d<\/a> by Veszpr\u00e9mi \u00c1llatkert, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\">CC BY-SA 3.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Aye-aye_at_night_in_the_wild_in_Madagascar.jpg\">Aye-aye at night in the wild in Madagascar<\/a> by Frank Vassen, <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/deed.en\">CC BY 2.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Diademed_ready_to_push_off.jpg\">Diademed ready to push off<\/a> by Michael Hogan, designated to the <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/cc0\/\">public domain (CC0)<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Juvenile_Black-and-White_Ruffed_Lemur,_Mantadia,_Madagascar.jpg\">Juvenile Black-and-White Ruffed Lemur, Mantadia, Madagascar<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/42244964@N03\">Frank Vassen<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/legalcode\">CC BY 2.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Microcebus_murinus_-Artis_Zoo,_Amsterdam,_Netherlands-8a.jpg\">Microcebus murinus -Artis Zoo, Amsterdam, Netherlands-8a<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/46956042@N00\">Arjan Haverkamp<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/legalcode\">CC BY 2.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Slow_Loris.jpg\">Slow Loris<\/a> by Jmiksanek, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\">CC BY-SA 3.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Slender_Loris.jpg\">Slender Loris<\/a> by Kalyan Varma (<a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Kalyanvarma\">Kalyanvarma<\/a>), <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\">CC BY-SA 4.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Garnett&apos;s_Galago_(Greater_Bushbaby).jpg\">Garnett's Galago (Greater Bushbaby)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/23661161@N02\">Mark Dumont<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/legalcode\">CC BY 2.0<\/a>.]<\/figcaption><\/figure>\n<p>The Order Primates is subdivided into Suborder Strepsirrhini and Suborder Haplorrhini, which, according to molecular estimates, split about 70\u201380 million years ago (Pozzi et al. 2014). The strepsirrhines include the groups commonly called lemurs, lorises, and galagos (Figure 6.15). Strepsirrhines differ from haplorrhines in many ways, most of which involve retaining ancestral traits from the earliest primates. Strepsirrhines do have two key derived traits that evolved after they diverged from the haplorrhines: the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1202\">grooming claw<\/a> <\/strong>(Figure 6.16) on the second digit of each foot, and the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1204\">tooth comb<\/a><\/strong> (or <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1206\">dental comb<\/a><\/strong>) located on the lower, front teeth (Figure 6.17). In most strepsirrhines, there are six teeth in the toothcomb\u2014four incisors and two canines. Other than the tooth comb, the teeth of strepsirrhines are fairly simple and are neither large or distinctive relative to haplorrhines.<\/p>\n<figure style=\"width: 237px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image18.jpg\" alt=\"A long, thin dark claw is visible in contrast to flat dark nails on the other digits.\" width=\"237\" height=\"202\" \/><figcaption class=\"wp-caption-text\">Figure 6.16: The foot of a ring-tailed lemur showing its grooming claw on the second digit. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Lemur_catta_toilet_claw.jpg\">Lemur catta toilet claw<\/a> by Alex Dunkel (Maky) is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/3.0\/legalcode\">CC BY 3.0 License.<\/a><\/figcaption><\/figure>\n<p class=\"import-Normal\">Compared to haplorrhines, strepsirrhines rely more on nonvisual senses. Strepsirrhines get their name because they have wet noses (<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1208\">rhinariums<\/a><\/strong>) like cats and dogs, a trait that, along with a longer snout, reflect strepsirrhines\u2019 greater reliance on olfaction relative to haplorrhines. Many strepsirrhines use <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1210\">scent marking<\/a><\/strong>, including rubbing scent glands or urine on objects in the environment to communicate with others. Additionally, many strepsirrhines have mobile ears that they use to locate insect prey and predators. While strepsirrhines have a better sense of smell than haplorrhines, their visual adaptations are more ancestral. Strepsirrhines have less convergent eyes than haplorrhines and therefore all have postorbital bars, whereas haplorrhines have full postorbital closure (see Figure 6.2). All strepsirrhines have a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1212\">tapetum lucidum<\/a><\/strong>, a reflective layer at the back of the eye that reflects light and thereby enhances the ability to see in low-light conditions. It is the same layer that causes your dog or cat to have \u201cyellow eye\u201d when you take photos of them with the flash on. This is a trait thought to be ancestral among mammals as a whole.<\/p>\n<figure style=\"width: 292px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image19-1.jpg\" alt=\"The lower, front teeth are long, thin, tightly together in a line, and project towards the lips.\" width=\"292\" height=\"354\" \/><figcaption class=\"wp-caption-text\">Figure 6.17: The lower front teeth of a ring-tailed lemur showing the six teeth of the tooth comb: four incisors and two canines. The teeth that superficially look like canines are premolars. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Lemur_catta_toothcomb.jpg\">Lemur catta toothcomb<\/a> by Alex Dunkel (Maky) is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/3.0\/legalcode\">CC BY 3.0 license.<\/a><\/figcaption><\/figure>\n<p class=\"import-Normal\">Strepsirrhines also differ from haplorrhines in some aspects of their ecology and behaviour. The majority of strepsirrhines are solitary, traveling alone to search for food; a few taxa are more social. Most strepsirrhines are also nocturnal and arboreal. Strepsirrhines are, on average, smaller than haplorrhines, and so many of them have a diet consisting of insects and fruit, with few taxa eating primarily leaves. Lastly, most strepsirrhines are good at leaping, with several taxa specialized for vertical clinging and leaping. In fact, among primates, all but one of the vertical clinger leapers belong to the Suborder Strepsirrhini.<\/p>\n<p class=\"import-Normal\">Strepsirrhines can be found all across Asia, Africa, and on the island of Madagascar (Figure 6.18). The Suborder Strepsirrhini is divided into two groups: (1) the lemurs of Madagascar and (2) the lorises, pottos, and galagos of Africa and Asia. By molecular estimates, these two groups split about 65 million years ago (Pozzi Et al. 2014).<\/p>\n<figure style=\"width: 443px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image20-1.png\" alt=\"Map strepsirrhine primates locations.\" width=\"443\" height=\"342\" \/><figcaption class=\"wp-caption-text\">Figure 6.18: Geographic distribution of living strepsirrhines. Lemurs live only on Madagascar, while lorises and galagos live across Central Africa and South and Southeast Asia. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\">Geographic distribution of living strepsirrhines (Figure 5.16)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Elyssa Ebding at <a href=\"https:\/\/www.csuchico.edu\/geop\/geoplace\/index.shtml\">GeoPlace, California State University, Chico<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<h4><em>Lemurs of Madagascar<\/em><\/h4>\n<p class=\"import-Normal\">Madagascar is an island off the east coast of Africa, and it is roughly the size of California, Oregon, and Washington combined. It has been separated from Africa for about 130 million years and from India for about 85 million years, which means it was already an island when strepsirrhines got there approximately 60\u201370 million years ago. Only a few mammal species ever reached Madagascar, and so when lemurs arrived they were able to flourish into a variety of forms.<\/p>\n<p class=\"import-Normal\">The lemurs of Madagascar are much more diverse compared to their mainland counterparts, the lorises and galagos. While many Malagasy strepsirrhines are nocturnal, plenty of others are diurnal or cathemeral. They range in body size from the smallest of all primates, the mouse lemur, some species of which weigh a little over an ounce (see Figure 6.15), up to the largest of all strepsirrhines, the indri, which weighs up to about 20 pounds (Figure 6.19). Lemurs include species that are insectivorous, frugivorous, and folivorous. A couple of members of this group have unusual diets for primates, including the gummivorous fork-marked and bamboo lemurs, who are able to metabolize the cyanide in bamboo. The most unique lemur is the aye-aye (depicted in Figure 6.15). This nocturnal lemur has rodent-like front teeth that grow continuously and a long-bony middle finger that it uses to fish grubs out of wood. It has a very large brain compared to other strepsirrhines, which it fuels with a diet that includes bird\u2019s eggs and other animal matter. Based on genetic estimates and morphological studies, it is believed that aye-ayes were the first lemurs to separate from all other strepsirrhines and to evolve on their own since strepsirrhines arrived in Madagascar (Matsui Et al. 2009).<\/p>\n<figure style=\"width: 326px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image21-1-1.jpg\" alt=\"Two Indis in a tree.\" width=\"326\" height=\"217\" \/><figcaption class=\"wp-caption-text\">Figure 6.19: Indris, the largest of the lemurs. These folivorous lemurs are vertical clingers and leapers and live in pairs. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Indri_indri_0003.jpg\">Indri indri 0003<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Christophe_Germain\">Christophe Germain<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Lemurs are also diverse in terms of social behaviour: Many lemurs are solitary foragers, some live in pairs, others in small groups, still others in larger groups, and some, like the red-ruffed lemur, live in unique and complex social groups (Vasey 2006). Lemurs include some of the best vertical clingers and leapers, and while many lemurs are quadrupedal, even the quadrupedal lemurs are quite adept at leaping. Malagasy strepsirrhines also exhibit a few unusual traits. They are highly seasonal breeders, often mating only during a short window once a year (Wright 1999). Female ring-tailed lemurs, for example, come into estrus one day a year for a mere six hours. Unlike most primates, where males are typically large and dominant, Malagasy strepsirrhines feature socially dominant females that are similar in size to males and have priority access to resources.<\/p>\n<h4 class=\"import-Normal\"><em>Lorises, Pottos, and Galagos of Asia and Africa<\/em><\/h4>\n<figure style=\"width: 207px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image22-1.jpg\" alt=\"Slow loris hanging from a branch.\" width=\"207\" height=\"309\" \/><figcaption class=\"wp-caption-text\">Figure 6.20: This slow loris, like all others in this taxonomic group, is solitary and nocturnal, with a diet heavy in insects and fruit. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Nycticebus_coucang_002.jpg\">Nycticebus coucang 002<\/a> by David Haring \/ Duke Lemur Center is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/deed.en\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p>Unlike the lemurs of Madagascar, lorises, pottos, and galagos live in areas where they share their environments with monkeys and apes, who often eat similar foods. Lorises live across South and Southeast Asia, while pottos and galagos live across Central Africa. Because of competition with larger-bodied monkeys and apes, mainland strepsirrhines are more restricted in the niches they can fill in their environments and so are less diverse than the lemurs.<\/p>\n<p>The strepsirrhines of Africa and Asia are all nocturnal and solitary, with little variation in body size and diet. For the most part, the diet of lorises, pottos, and galagos consists of fruits and insects. A couple of species eat more gum, but overall the diet of this group is narrow when compared to the Malagasy lemurs. Lorises (Figure 6.20) and pottos are known for being slow, quadrupedal climbers, moving quietly through the forests to avoid being detected by predators. These strepsirrhines have developed additional defences against predators. Lorises, for example, eat a lot of caterpillars, which makes their saliva slightly toxic. Loris mothers bathe their young in this toxic saliva, making the babies unappealing to predators. In comparison to the slow-moving lorises and pottos, galagos are active quadrupedal runners and leapers that scurry about the forests at night. Galagos make distinctive calls that sound like a baby crying, which has led to their nickname \u201cbushbabies.\u201d Figure 6.21 summarizes the key differences between these two groups of strepsirrhines.<\/p>\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<caption>Figure 6.21: Strepsirrhini at a glance: This table summarizes the key differences between the two groups of strepsirrhines. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\">Strepsirrhines at a glance table (Figure 5.19)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\">CC BY-NC-SA 4.0 License<\/a>. [Includes <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Ringtailed_Lemurs_in_Berenty.jpg\">Ringtailed Lemurs in Berenty<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/50852241@N00\">David Dennis<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\">CC BY-SA 2.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Komba_u%C5%A1at%C3%A1.jpg\">Komba u\u0161at\u00e1<\/a> by Petr Hamern\u00edk, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\">CC BY-SA 4.0<\/a>.]<\/caption>\n<thead>\n<tr>\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong><img class=\"alignnone\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image23-1.jpg\" alt=\"Baby primate on the back of adult primate.\" width=\"231\" height=\"165\" \/><\/strong><\/p>\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Lemurs<\/strong><\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong><img class=\"alignnone\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image24-1.jpg\" alt=\"Small primate with big eyes and long tail.\" width=\"198\" height=\"132\" \/><\/strong><\/p>\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Lorises, Pottos, and Galagos<\/strong><\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"a0-R\">\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Geographic range<\/strong><\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Madagascar<\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">South and Southeast Asia<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Central Africa<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a0-R\">\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Activity patterns<\/strong><\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Diurnal, nocturnal, or cathemeral<\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Nocturnal<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a0-R\">\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Dietary types<\/strong><\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Insectivore, frugivore, or folivore<\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Insectivore, frugivore<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a0-R\">\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Social groupings<\/strong><\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Solitary, pairs, or small to large groups<\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Solitary<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a0-R\">\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Forms of locomotion<\/strong><\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Vertical clinger leapers, quadrupedal<\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Slow quadrupedal climbers and active quadrupedal runners<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h3 class=\"import-Normal\"><strong>Suborder Haplorrhini<\/strong><\/h3>\n<p class=\"import-Normal\">When the two primate suborders split from one another, strepsirrhines retained more ancestral traits while haplorrhines developed more derived traits, which are discussed below.<\/p>\n<p class=\"import-Normal\">As mentioned earlier, haplorrhines have better vision than strepsirrhines. This is demonstrated by the full postorbital closure protecting the more convergent eyes that haplorrhines possess (with one exception seen in Figure 6.2). Most haplorrhines are trichromatic, and all have a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1410\">fovea<\/a><\/strong>, a depression in the retina at the back of the eye containing concentrations of cells that allows them to see things very close up in great detail. The heavier reliance on vision over olfaction is also reflected in the shorter snouts ending with the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1412\">dry nose<\/a> <\/strong>(no rhinarium) of haplorrhines. All but two genera of living haplorrhines are active during the day, so this group lacks the tapetum lucidum that is so useful to nocturnal species. On average, haplorrhines also have larger brains relative to their body size when compared with strepsirrhines.<\/p>\n<p class=\"import-Normal\">The Haplorrhini differ from the Strepsirrhini in their ecology and behaviour as well. Haplorrhines are generally larger than strepsirrhines, and they tend to be folivorous and frugivorous. This dietary difference is reflected in the teeth of haplorrhines, which are broader with more surface area for chewing. The larger body size of this taxon also influences locomotion. Only one haplorrhine is a vertical clinger and leaper. Most members of this suborder are quadrupedal, with one subgroup specialized for brachiation. A few haplorrhine taxa are <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1414\">monomorphic<\/a><\/strong>, meaning males and females are the same size, but many members of this group show moderate to high sexual dimorphism in body size and canine size. Haplorrhines also differ in social behaviour. All but two haplorrhines live in groups, which is very different from the primarily solitary strepsirrhines. Differences between the two suborders are summarized in Figure 6.22.<\/p>\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<caption>Figure 6.22: Suborders at a glance: This table summarizes the key differences between the two primate suborders. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\">Suborders at a glance table (Figure 5.20)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\">CC BY-NC-SA 4.0 License<\/a>. [Includes <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Black-and-White_Ruffed_Lemur,_Mantadia,_Madagascar.jpg\">Black-and-White Ruffed Lemur, Mantadia, Madagascar<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/42244964@N03\">Frank Vassen<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/legalcode\">CC BY 2.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Crab_eating_macaque_face.jpg\">Crab eating macaque face<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Bruce89\">Bruce89<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\">CC BY-SA 4.0<\/a>.]<\/caption>\n<thead>\n<tr>\n<td class=\"a1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong><img class=\"alignnone\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image25.jpg\" alt=\"Black-and-white ruffed lemur.\" width=\"213\" height=\"159\" \/><\/strong><strong>Suborder Strepsirrhini<\/strong><\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong><img class=\"alignnone\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image26-1.jpg\" alt=\"Crab-eating macaque.\" width=\"137\" height=\"137\" \/><\/strong><\/p>\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Suborder Haplorrhini<\/strong><\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"a1-R\">\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Sensory adaptations<\/strong><\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Rhinarium<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Longer snout<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Eyes less convergent<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Postorbital bar<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Tapetum lucidum<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Mobile ears<\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">No rhinarium<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Short snout<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Eyes more convergent<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Postorbital plate<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">No tapetum lucidum<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Many are trichromatic<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Fovea<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a1-R\">\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Dietary differences<\/strong><\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Mostly insectivores and frugivores, few folivores<\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Few insectivores, mostly frugivores and folivores<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a1-R\">\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Activity patterns and Ecology<\/strong><\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Mostly nocturnal, few diurnal or cathemeral<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Almost entirely arboreal<\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Only two are nocturnal, rest are diurnal<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Many arboreal taxa, also many terrestrial taxa<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a1-R\">\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Social groupings<\/strong><\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Mostly solitary, some pairs, small to large groups<\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Only two are solitary, all others live in pairs, small to very large groups<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a1-R\">\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Sexual dimorphism<\/strong><\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Minimal to none<\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Few taxa have little\/none, many taxa show moderate to high dimorphism<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p class=\"import-Normal\">Suborder Haplorrhini is divided into three infraorders: Tarsiiformes, which includes the tarsiers of Asia; Platyrrhini, which includes the monkeys of Central and South America; and Catarrhini, a group that includes the monkeys of Asia and Africa, apes, and humans. According to molecular estimates, tarsiers split from the other haplorrhines close to 70 million years ago, and platyrrhines split from catarrhines close to 46 million years ago (Pozzi Et al. 2014).<\/p>\n<h4 class=\"import-Normal\"><em>Infraorder Tarsiiformes of Asia<\/em><\/h4>\n<figure style=\"width: 188px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image27-1.jpg\" alt=\"Tarsier gripping a branch.\" width=\"188\" height=\"160\" \/><figcaption class=\"wp-caption-text\">Figure 6.23: Tarsiers are the only living representatives of this Infraorder. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Tarsier_Sanctuary,_Corella,_Bohol_(2052878890).jpg\">Tarsier Sanctuary, Corella, Bohol (2052878890)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/46274125@N00\">yeowatzup<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/legalcode\">CC BY 2.0 License<\/a>.<\/figcaption><\/figure>\n<figure style=\"width: 362px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image28-1.png\" alt=\"Map of Southeast Asia shows distribution of tarsiers.\" width=\"362\" height=\"279\" \/><figcaption class=\"wp-caption-text\">Figure 6.24: Tarsiiformes are found in the tropical forests of multiple islands in Southeast Asia including Sumatra, Borneo, Celebes, and the Philippines. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\">Infraorder Tarsiiformes of Asia map (Figure 5.22)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Elyssa Ebding at <a href=\"https:\/\/www.csuchico.edu\/geop\/geoplace\/index.shtml\">GeoPlace, California State University, Chico<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p>Today, the Infraorder Tarsiiformes includes only one genus, <em>Tarsius <\/em>(Figure 6.23). Tarsiers are small-bodied primates that live in Southeast Asian forests (Figure 6.24) and possess an unusual collection of traits that have led to some debate about their position in the primate taxonomy. They are widely considered members of the haplorrhine group because they share several derived traits with monkeys, apes, and humans, including dry noses, a fovea, not having a tapetum lucidum, and eyes that are more convergent. Tarsiers also have some traits that are more like strepsirrhines and some that are unique. Tarsiers are the only haplorrhine that are specialized vertical clinger leapers, a form of locomotion only otherwise seen in some strepsirrhines. Tarsiers actually get their name because their ankle (tarsal) bones are elongated to provide a lever for vertical clinging and leaping. Tarsiiformes are also small, with most species weighing between 100 and 150 grams. Like strepsirrhines, tarsiers are nocturnal, but because they lack a tapetum lucidum, tarsiers compensate by having enormous eyes. In fact, each eye of a tarsier is larger than its brain. These large eyes allow enough light in for tarsiers to still be able to see well at night without the reflecting layer in their eyes. To protect their large eyes, tarsiers have a partially closed postorbital plate that appears somewhat intermediate between the postorbital bar of strepsirrhines and the full postorbital closure of other haplorrhines (Figure 6.25). Tarsiers have different dental formulas on their upper and lower teeth. On the top, the dental formula is 2:1:3:3, but on the bottom it is 1:1:3:3. Other unusual traits of tarsiers include having two grooming claws on each foot and the ability to rotate their heads around 180 degrees, a trait useful in locating insect prey. The tarsier diet is considered <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1416\">faunivorous<\/a> <\/strong>because it consists entirely of animal matter, making them the only primate not to eat any vegetation. They are only one of two living haplorrhines to be solitary, the other being the orangutan. Most tarsiers are not sexually dimorphic, like strepsirrhines, although males of a few species are slightly larger than females.<\/p>\n<figure style=\"width: 486px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image29-1.jpg\" alt=\"Front view of tarsier skull.\" width=\"486\" height=\"323\" \/><figcaption class=\"wp-caption-text\">Figure 6.25: Skull of a tarsier showing very large eye sockets and partially closed postorbital plates. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Tarsier_skull.jpg\">Tarsier skull<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/65438265@N00\">Andrew Bardwell<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\">CC BY-SA 2.0 License.<\/a><\/figcaption><\/figure>\n<p class=\"import-Normal\">Two alternative classifications have emerged due to the unusual mix of traits that tarsiers have. Historically, tarsiers were grouped with lemurs, lorises, and galagos into a suborder called Prosimii. This classification was based on tarsiers, lemurs, lorises, and galagos all having grooming claws and similar lifestyles. Monkeys, apes, and humans were then separated into a suborder called the Anthropoidea. These suborder groupings were based on <em>grade<\/em> rather than <em>clade<\/em>. Today, most people use Suborders Strepsirrhini and Haplorrhini, which are clade groupings based on the derived traits that tarsiers share with monkeys, apes, and humans. The Strepsirrhini\/Haplorrhini dichotomy is also supported by the genetic evidence that indicates tarsiers are more closely related to monkeys, apes, and humans (Jameson Et al. 2011). Figure 6.26 summarizes the unusual mix of traits seen in tarsiers.<\/p>\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<caption>Figure 6.26: Tarsiers at a glance: Tarsiers have a mix of traits that lead to debate about their classification. While they have some unique characteristics, they also have traits that superficially resemble strepsirrhines, and many derived traits shared with haplorrhines. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\">Tarsiers at a glance table (Figure 5.24)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/caption>\n<thead>\n<tr>\n<td class=\"a2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Like Strepsirrhini<\/strong><\/p>\n<\/td>\n<td class=\"a2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Unique<\/strong><\/p>\n<\/td>\n<td class=\"a2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Like Haplorrhini<\/strong><\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"a2-R\">\n<td class=\"a2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Very small<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Nocturnal<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Highly insectivorous<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Solitary<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Vertical clinger-leapers<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Little\/no sexual dimorphism<\/p>\n<\/td>\n<td class=\"a2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Two grooming claws<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">2:1:3:3\/1:1:3:3 dental formula<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Do not eat vegetation<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Can rotate their heads nearly 180 degrees<\/p>\n<\/td>\n<td class=\"a2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Almost full PO closure<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">More convergent eyes<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">No tapetum lucidum<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">No rhinarium<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Genetic evidence<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Fovea<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h4 class=\"import-Normal\"><em>Infraorder Platyrrhini of Central and South America<\/em><\/h4>\n<figure id=\"attachment_179-2\" aria-describedby=\"caption-attachment-179-2\" style=\"width: 329px\" class=\"wp-caption alignleft\"><img class=\"wp-image-165\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image30-e1686352290168.png\" alt=\"Map of South America shows where platyrrhines live.\" width=\"329\" height=\"324\" \/><figcaption id=\"caption-attachment-179-2\" class=\"wp-caption-text\">Figure 6.27: Geographic distribution of the platyrrhines across the southern part of Central America and the tropical and termporate regions of South America. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\">Infraorder Platyrrhini map<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Elyssa Ebding at <a href=\"https:\/\/www.csuchico.edu\/geop\/geoplace\/index.shtml\">GeoPlace, California State University, Chico<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p>The platyrrhines are the only nonhuman primates in Central and South America (Figure 6.27) and so, like the lemurs of Madagascar, have diversified into a variety of forms in the absence of competition. Infraorder Platyrrhini get their name from their distinctive nose shape. \u201cPlaty\u201d means flat and \u201crhini\u201d refers to noses, and, indeed, platyrrhines have noses that are flat and wide, with nostrils that are far apart, facing outward, and usually round in shape (Figure 6.28). This nose shape is very different from what we see in catarrhines.<\/p>\n<p>On average, platyrrhines are smaller and less sexually dimorphic than catarrhines, and they have retained the more ancestral primate dental formula of 2:1:3:3. Platyrrhines are all highly arboreal, whereas many catarrhines spend significant time on the ground. The monkeys in Central and South America also differ in having less well-developed vision. This is reflected in the wiring in the visual system of the brain as well as in their <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1418\">polymorphic color vision<\/a><\/strong>. The genes that enable individuals to distinguish reds and yellows from blues and greens are on the X chromosome. Different genes code for being able to see different wavelengths of light so to distinguish between them you need to be heterozygous for seeing colour. The X chromosomes of platyrrhines each carry the genes for seeing one wavelength, so male platyrrhines (with only one X chromosome) are always dichromatic. Female platyrrhines can be dichromatic (if they are homozygous for one version of the colour vision gene) or trichromatic (if they are heterozygous) (Kawamura Et al. 2012). We currently know of two exceptions to this pattern among platyrrhines. Nocturnal owl monkeys are <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1420\">monochromatic<\/a><\/strong>, meaning that they cannot distinguish any colours. The other exception are howler monkeys, which have evolved to have two colour vision genes on each X chromosome. This means that both male and female howler monkeys are able to see reds and yellows. By contrast, catarrhine males and females are all trichromatic.<\/p>\n<figure style=\"width: 279px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image31-1.jpg\" alt=\"White-faced capuchin monkey.\" width=\"279\" height=\"190\" \/><figcaption class=\"wp-caption-text\">Figure 6.28: A capuchin monkey demonstrating a typical platyrrhine nose shape with round nostrils pointing outward on a flat nose. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:CARABLANCA_-_panoramio.jpg\">CARABLANCA - panoramio<\/a> by Manuel Velazquez is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/3.0\/legalcode\">CC BY 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Platyrrhines include the smallest of the monkeys, the marmosets and tamarins (Figure 6.29), all of which weigh less than one kilogram and live in cooperative family groups, wherein usually only one female reproduces and everyone else helps carry and raise the offspring. They are unusual primates in that they regularly produce twins. Marmosets and tamarins largely eat gums and saps, so these monkeys have evolved claw-like nails that enable them to cling to the sides of tree trunks like squirrels as well as special teeth that allow them to gnaw through bark. Except for the Goeldi\u2019s monkey, these small monkeys have one fewer molar than other platyrrhines, giving them a dental formula of 2:1:3:2.<\/p>\n<figure style=\"width: 428px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image32-1.jpg\" alt=\"Six marmoset and tamarin species.\" width=\"428\" height=\"470\" \/><figcaption class=\"wp-caption-text\">Figure 6.29: Clockwise from top right: golden-headed lion tamarin, pygmy marmoset, Goeldi\u2019s monkey, bare-eared marmoset, emperor tamarin, and common marmoset. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Callitrichinae_genus.jpg\">Callitrichinae genus<\/a> by Miguelrangeljr is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/deed.en\">CC BY-SA 3.0 License<\/a>. [Includes <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Wei%C3%9Fb%C3%BCschelaffe_(Callithrix_jacchus).jpg\">Wei\u00dfb\u00fcschelaffe_(Callithrix_jacchus)<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Raymond\">Raymond<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/\">CC BY-SA 4.0<\/a>;\u00a0 <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Leontopithecus_chrysomelas_(portrait).jpg\">Leontopithecus chrysomelas (portrait)<\/a> by Hans Hillewaert, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/\">CC BY-SA 4.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Emperor_Tamarin_portrait_2_edit1.jpg\">Emperor_Tamarin_portrait_2_edit1<\/a> by <a href=\"https:\/\/sites.google.com\/site\/thebrockeninglory\/\">Brocken Inaglory<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/\">CC BY-SA 4.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Dv%C3%A6rgsilkeabe_Callithrix_pygmaea.jpg\">Dv\u00e6rgsilkeabe_Callithrix_pygmaea<\/a> by Malene Thyssen (User <a href=\"https:\/\/da.wikipedia.org\/wiki\/User:Malene\">Malene<\/a>), <a href=\"https:\/\/en.wikipedia.org\/wiki\/GNU_Free_Documentation_License\">GNU Free Documentation License<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Mico_argentatus_(portrait).jpg\">Mico_argentatus_(portrait)<\/a> by Hans Hillewaert, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/\">CC BY-SA 4.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Titi_Monkey.jpg\">Titi Monkey<\/a> by Jeff Kubina, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/deed.en\">CC BY-SA 2.0<\/a>].]<\/figcaption><\/figure>\n<p class=\"import-Normal\">The largest platyrrhines are a family that include spider monkeys, woolly spider monkeys, woolly monkeys, and howler monkeys (Figure 6.30). These monkeys can weigh up to 9\u201315 kg and have evolved prehensile tails that can hold their entire body weight. It is among this group that we see semi-brachiators, like the spider monkey (see Figure 6.13). To make them more efficient in this form of locomotion, spider monkeys evolved to not have thumbs so that their hands work more like hooks that can easily let go of branches while swinging. Howler monkeys are another well-known member of this group, earning their name due to their loud calls, which can be heard miles away. To make these loud vocalizations, howler monkeys have a specialized vocal system that includes a large larynx and hyoid bone. Howler monkeys are the most folivorous of the platyrrhines and are known for spending a large portion of their day digesting their food.<\/p>\n<figure style=\"width: 458px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image33-1.jpg\" alt=\"Four platyrrhine species.\" width=\"458\" height=\"457\" \/><figcaption class=\"wp-caption-text\">Figure 6.30: Clockwise from top right: howler monkey, woolly monkey, woolly spider monkey, and spider monkey. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Atelidae_Family.jpg\">Atelidae Family<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Miguelrangeljr\">Miguelrangeljr<\/a> is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\">CC BY-SA 3.0 License<\/a>. [Includes <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Ateles_marginatus_(Sao_Paulo_zoo).jpg\">Ateles marginatus (Sao Paulo zoo)<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Miguelrangeljr\">Miguelrangeljr<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\">CC BY-SA 3.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Alouatta_caraya_male.JPG\">Alouatta caraya male<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Miguelrangeljr\">Miguelrangeljr<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\">CC BY-SA 3.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Lagothrix_lagotricha_(walking).jpg\">Lagothrix lagotricha (walking)<\/a> by Hans Hillewaert, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\">CC BY-SA 3.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Brachyteles_hypoxanthus2.jpg\">Brachyteles hypoxanthus2<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/42956474@N04\/with\/4133258867\/\">Paulo B. Chaves<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/legalcode\">CC BY 2.0<\/a>.]<\/figcaption><\/figure>\n<p class=\"import-Normal\">There are many other monkeys in Central and South America, including the gregarious capuchins (see Figure 6.28) and squirrel monkeys, the pair-living titi monkeys, and the nocturnal owl monkeys. There are also the seed-eating saki monkeys and uakaris. In many areas across Central and South America, multiple species of platyrrhines share the forests, with some even traveling together in association. According to molecular evidence, the diversity of platyrrhines that we see today seems to have originated about 25 million years ago (Schneider &amp; Sampaio 2015). Figure 6.31 summarizes the key traits of platyrrhines relative to the other infraorders of Haplorrhini.<\/p>\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<caption>Figure 6.31: Platyrrhini at a glance: Summary of the key traits we use to distinguish platyrrhines. Traits indicated with an * are those with exceptions detailed in the text. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\">Platyrrhini at a glance table (Figure 5.29)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/caption>\n<tbody>\n<tr class=\"a3-R\">\n<td class=\"a3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Platyrrhini traits<\/strong><\/p>\n<\/td>\n<\/tr>\n<tr class=\"a3-R\">\n<td class=\"a3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Flat nose with rounded nostrils pointing to the side<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Highly arboreal<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Less sexually dimorphic on average<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">2:1:3:3 dental formula*<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Polymorphic colour vision*<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h4 class=\"import-Normal\"><em>Infraorder Catarrhini of Asia and Africa <\/em><\/h4>\n<figure style=\"width: 191px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image34.jpg\" alt=\"Wolf\u2019s guenon.\" width=\"191\" height=\"287\" \/><figcaption class=\"wp-caption-text\">Figure 6.32: A Wolf\u2019s guenon demonstrating a typical catarrhine nose with teardrop-shaped nostrils close together and pointed downward. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Wolf&apos;s_Guenon_Picking_Up_Food_(19095137693).jpg\">Wolf's Guenon Picking Up Food (19095137693)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/8749778@N06\">Eric Kilby<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\">CC BY-SA 2.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Infraorder Catarrhini includes Superfamily Cercopithecoidea (the monkeys of Africa and Asia) and Superfamily Hominoidea (apes and humans). Nonhuman catarrhines are found all over Africa and South and Southeast Asia, with some being found as far north as Japan. The most northerly and southerly catarrhines are cercopithecoid monkeys. In contrast, apes are less tolerant of drier, more seasonal environments and so have a relatively restricted geographic range.<\/p>\n<p class=\"import-Normal\">Relative to other haplorrhine infraorders, catarrhines are distinguished by several characteristics. Catarrhines have a distinctive nose shape, with teardrop-shaped nostrils that are close together and point downward (Figure 6.32) and one fewer premolar than most other primates, giving us a dental formula of 2:1:2:3 (Figure 6.33). On average, catarrhines are the largest and most sexually dimorphic of all primates. Gorillas are the largest living primates, with males weighing up to 220 kg. The most sexually dimorphic of all primates are mandrills. Mandrill males not only have much more vibrant colouration than mandrill females but also have larger canines and can weigh up to three times more (Setchell Et al. 2001). The larger body size of catarrhines is related to the more terrestrial lifestyle of many members of this infraorder. In fact, the most terrestrial of living primates can be found in this group. Among all primates, vision is the most developed in catarrhines. Catarrhines independently evolved the same adaptation as howler monkeys in having each X chromosome with genes to distinguish both reds and yellows, so all male and female catarrhines are trichromatic, which is useful for these diurnal primates.<\/p>\n<figure style=\"width: 632px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image35-1.jpg\" alt=\"Platyrrhine, cercopithecoid, and hominoid mandibles.\" width=\"632\" height=\"331\" \/><figcaption class=\"wp-caption-text\">Figure 6.33: Catarrhines have two premolars whereas most other primate taxa (including platyrrhini) have three premolars. This image also shows one of the derived traits of cercopithecoids, their bilophodont molars, which differ from the more ancestral Y-5 molars of apes and humans. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\">Platyrrhini vs. Catarrhini dentition<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\">CC BY-NC-SA 4.0 License<\/a>. [Includes <a href=\"https:\/\/animaldiversity.org\/accounts\/Animalia\/specimens\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Cebus_apella\/lower_dorsal2216\/?start=135;f=subject::specimen::lower%20jaw\">Cebus apella (brown capuchin)<\/a> at Animal Diversity Web by <a href=\"https:\/\/animaldiversity.org\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Hylobates_syndactylus\/lower_dorsal0097\/\">Phil Myers<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\">CC BY-NC-SA 3.0<\/a>; <a href=\"https:\/\/animaldiversity.org\/accounts\/Animalia\/specimens\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Lophocebus_albigena\/lower_dorsal2060\/?start=525;f=subject::specimen::lower%20jaw\">Lophocebus albigena (gray-cheeked mangaby)<\/a> at Animal Diversity Web by <a href=\"https:\/\/animaldiversity.org\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Hylobates_syndactylus\/lower_dorsal0097\/\">Phil Myers<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\">CC BY-NC-SA 3.0<\/a>; <a href=\"https:\/\/animaldiversity.org\/accounts\/Primates\/specimens\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Hylobates_syndactylus\/lower_dorsal0097\/?start=105;f=subject::specimen::lower%20jaw\">Symphalangus syndactylus (siamang)<\/a> at Animal Diversity Web by <a href=\"https:\/\/animaldiversity.org\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Hylobates_syndactylus\/lower_dorsal0097\/\">Phil Myers<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\">CC BY-NC-SA 3.0<\/a>.]<\/figcaption><\/figure>\n<p class=\"import-Normal\">The two superfamilies of catarrhines\u2014Superfamily Cercopithecoidea, the monkeys of Africa and Asia, and Superfamily Hominoidea, which includes apes and humans\u2014are believed to have split about 32 million years ago based on molecular evidence (Pozzi Et al. 2014). This fits with the fossil record, which shows evidence of these lineages by about 25 million years ago (see Chapters 8-9).<\/p>\n<h4 class=\"import-Normal\"><em>Superfamily Cercopithecoidea of Africa and Asia<\/em><\/h4>\n<figure style=\"width: 285px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image36-1.jpg\" alt=\"Pinkish ischial callosities on a crested black macaque.\" width=\"285\" height=\"214\" \/><figcaption class=\"wp-caption-text\">Figure 6.34: The second derived trait of cercopithecoids are their ischial callosities, shown here on a crested black macaque. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Sulawesi_trsr_DSCN0572_v1.JPG\">Sulawesi trsr DSCN0572 v1<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Shankar_Raman\">T. R. Shankar Ramanis<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\">CC BY-SA 3.0 License.<\/a><\/figcaption><\/figure>\n<p>Compared to hominoids, cercopithecoids have an ancestral quadrupedal body plan with two key derived traits. The first derived trait of cercopithecoids is their <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1422\">bilophodont<\/a> <\/strong>molars (\u201cbi\u201d meaning two, \u201cloph\u201d referring to ridge, and \u201cdont\u201d meaning tooth). If you refer back to Figure 6.33, you will see how the molars of cercopithecoids have four cusps arranged in a square pattern and have two ridges connecting them. It is thought that this molar enabled these monkeys to eat a wide range of foods, thus allowing them to live in habitats that apes cannot. The other key derived trait that all cercopithecoids share is having <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1424\">ischial callosities<\/a> <\/strong>(Figure 6.34). The ischium is the part of your pelvis that you are sitting on right now (see Appendix A: Osteology). In cercopithecoids, this part of the pelvis has a flattened surface that, in living animals, has callused skin over it. These function as seat pads for cercopithecoids, who often sit above branches when feeding and resting.<\/p>\n<figure style=\"width: 359px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image37-1.png\" alt=\"Areas of Europe, Asia, Africa, and Australia where cercopithecoids live.\" width=\"359\" height=\"277\" \/><figcaption class=\"wp-caption-text\">Figure 6.35: Geographic distribution of the cercopithecoid monkeys. Catarrhines have the widest geographic distribution due to the success of cercopithecoids who are found all across subsaharan Africa and southern Asia. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\">Superfamily Cercopithecoidea map (Figure 5.33)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Elyssa Ebding at <a href=\"https:\/\/www.csuchico.edu\/geop\/geoplace\/index.shtml\">GeoPlace, California State University, Chico<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p>Cercopithecoid monkeys are the most geographically widespread group of nonhuman primates (Figure 6.35). Since their divergence from hominoids, this monkey group has increased in numbers and diversity due, in part, to their fast reproductive rates. On average, cercopithecoids will reproduce every one to two years, whereas hominoids will reproduce once every four to nine years, depending on the taxon.<\/p>\n<figure style=\"width: 180px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image38-1.jpg\" alt=\"Two silver leaf monkeys hold orange-haired infants.\" width=\"180\" height=\"240\" \/><figcaption class=\"wp-caption-text\">Figure 6.36: Silver leaf monkey infants are born with orange fur, dramatically contrasting the adult coat colour of their mothers. After a few months, the infants gradually change colour to that of their parents. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Silverleaf_Monkey_(Kuala_Lumpur).jpg\">Silverleaf Monkey (Kuala Lumpur)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/10815162@N07\">Andrea Lai<\/a> from Auckland, New Zealand, is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/legalcode\">CC BY 2.0 License.<\/a><\/figcaption><\/figure>\n<p>Cercopithecoidea is split into two groups, the leaf monkeys and the cheek-pouch monkeys. Both groups coexist in Asia and Africa; however, the majority of leaf monkey species live in Asia with only a few taxa in Africa. In contrast, only one genus of cheek-pouch monkey lives in Asia, and all the rest of them in Africa. As you can probably guess based on their names, the two groups differ in terms of diet. Leaf monkeys are primarily folivores, with some species eating a significant amount of seeds. Cheek-pouch monkeys tend to be more frugivorous or omnivorous, with one taxon, geladas, eating primarily grasses. The two groups also differ in some other interesting ways. Leaf monkeys tend to produce infants with <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1426\">natal coats<\/a><\/strong>\u2014infants whose fur is a completely different colour from their parents (Figure 6.36). Leaf monkeys are also known for having odd noses (Figure 6.37), and so they are sometimes called \u201codd-nosed monkeys.\u201d Cheek-pouch monkeys are able to pack food into their cheek pouches (Figure 6.38), thus allowing them to move to a location safe from predators or aggressive individuals of their own species where they can eat in peace.<\/p>\n<figure style=\"width: 408px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image39.jpg\" alt=\"Male proboscis monkey.\" width=\"408\" height=\"272\" \/><figcaption class=\"wp-caption-text\">Figure 6.37: Proboscis monkeys are one of several \u201codd-nosed\u201d leaf monkeys. Male proboscis monkeys, like this one, have large, pendulous noses, while females have much smaller noses. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Proboscis_monkey_(Nasalis_larvatus)_male_head.jpg\">Proboscis monkey (Nasalis larvatus) male head<\/a> by <a href=\"https:\/\/www.sharpphotography.co.uk\/\">Charles J Sharp<\/a> creator QS:P170,Q54800218 is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<figure style=\"width: 414px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image40-1.jpg\" alt=\"Bonnet macaque with full cheek pouches.\" width=\"414\" height=\"275\" \/><figcaption class=\"wp-caption-text\">Figure 6.38: This bonnet macaque has filled its cheek pouches with food, an adaptation that is useful in transporting food to a safer location to eat. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Bonnet_macaque_DSC_0893.jpg\">Bonnet macaque DSC 0893<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Shankar_Raman\">T. R. Shankar Raman<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<h4 class=\"import-Normal\"><em>Superfamily Hominoidea of Africa and Asia<\/em><\/h4>\n<figure style=\"width: 438px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image41.png\" alt=\"Areas of Europe, Asia, Africa, and Australia where hominoidea live.\" width=\"438\" height=\"339\" \/><figcaption class=\"wp-caption-text\">Figure 6.39: Geographic distribution of apes across Central and West Africa and Southeast Asia. Hominoids overlap geographically with cercopithecoid monkeys but have a lower tolerance for seasonal environments and so are found only in tropical forests across these regions. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\">Superfamily Hominoidea map (Figure 5.38)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Elyssa Ebding at <a href=\"https:\/\/www.csuchico.edu\/geop\/geoplace\/index.shtml\">GeoPlace, California State University, Chico<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Superfamily Hominoidea of Africa and Asia (Figure 6.39) includes the largest of the living primates: apes and humans. Whereas cercopithecoid monkeys have bilophodont molars, hominoids have the more ancestral <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1428\">Y-5 molars<\/a><\/strong>, which feature five cusps separated by a \u201cY\u201d-shaped groove pattern (see Figure 6.33). The Y-5 molar was present in the common ancestors of hominoids and cercopithecoids, thus it is the more ancestral molar pattern of the two. Hominoids differ the most from other primates in our body plans, due to the unique form of locomotion that hominoids are adapted for: brachiation (Figure 6.40).<\/p>\n<p>To successfully swing below branches, many changes to the body needed to occur. Hominoid arms are much longer than the legs to increase reach, and the lower back is shorter and less flexible to increase control when swinging. The torso, shoulders, and arms of hominoids have evolved to increase range of motion and flexibility (see again Figure 6.12). The clavicle, or collar bone, is longer to stabilize the shoulder joint out to the side, thus enabling us to rotate our arms 360 degrees. Hominoid rib cages are wider side to side and shallower front to back than those of cercopithecoids and we do not have tails, as tails are useful for balance when running on all fours but generally not useful while swinging. Hominoids also have modified ulnae, one of the two bones in the forearm (see Appendix A: Osteology). At the elbow end of the ulna, hominoids have a short <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1430\">olecranon process<\/a><\/strong>, which allows for improved extension in our arms. At the wrist end of the ulna, hominoids have a short <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1432\">styloid process<\/a><\/strong>, which enables us to have very flexible wrists, a trait critical for swinging. Both the olecranon process and styloid process are long in quadrupedal animals who carry much of their weight on their forelimbs when traveling and who therefore need greater stability rather than flexibility in those joints.<\/p>\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<caption>Figure 6.40: Quadrupedalism vs. brachiation: Summary of the key anatomical differences between a quadrupedal primate and one adapted for brachiation. To view these traits using photos of bones, check out the interactive skeletal websites in \u201cFurther Explorations\u201d below. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\">Quadrupedalism vs. Brachiation table (Figure 5.39)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/caption>\n<thead>\n<tr>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Quadrupedalism<\/strong><\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Brachiation<\/strong><\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"a4-R\">\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Arm length vs. leg length<\/strong><\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">About equal<\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Arms are longer<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a4-R\">\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Shoulder position<\/strong><\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">More on the front<\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Out to the side<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a4-R\">\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Ribcage shape<\/strong><\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Deep front-to-back<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Narrow side-to-side<\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Shallow front-to-back<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Wide side-to-side<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a4-R\">\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Length of lower back<\/strong><\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Long<\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Short<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a4-R\">\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Collar bone length<\/strong><\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Short<\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Long<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a4-R\">\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Ulnar olecranon process<\/strong><\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Long<\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Short<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a4-R\">\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Ulnar styloid process<\/strong><\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Long<\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Short<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a4-R\">\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Tail<\/strong><\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Short to long<\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">None<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p class=\"import-Normal\">Apes and humans also differ from other primates in behaviour and life history characteristics. Hominoids all seem to show some degree of female dispersal at sexual maturity but, as you will learn in Chapter 7, it is more common that males leave. Some apes show males dispersing in addition to females, but the hominoid tendency for female dispersal is a bit unusual among primates. Our superfamily is also characterized by the most extended life histories of all primates. All members of this group take a long time to grow and reproduce much less frequently compared to cercopithecoids. The slow pace of this life history is likely related to why hominoids have decreased in diversity since they first evolved. Figure 6.41 summarizes the key traits of Infraorder Catarrhini and its two superfamilies. Today, there are only five types of hominoids left: gibbons and siamangs, orangutans, gorillas, chimpanzees and bonobos, and humans.<\/p>\n<table class=\"aligncenter\">\n<caption>Figure 6.41a: Catarrhini at a glance: Summary of key traits of the Infraorder Catarrhini. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\">Catarrhini at a glance (Figure 5.40)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>. [Includes <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Duskyleafmonkey1.jpg\">Duskyleafmonkey1<\/a> by <a href=\"https:\/\/www.the-ninth.com\/about\">Robertpollai<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by\/3.0\/at\/deed.en\">CC BY 3.0 AT<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Male_Bornean_Orangutan_-_Big_Cheeks.jpg\">Male Bornean Orangutan - Big Cheeks<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/8749778@N06\">Eric Kilby<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\">CC BY-SA 2.0<\/a>.]<\/caption>\n<thead>\n<tr style=\"height: 22pt\">\n<td class=\"a5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\" colspan=\"2\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Infraorder Catarrhini<\/strong><\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"a5-R\" style=\"height: 22pt\">\n<td class=\"a5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\" colspan=\"2\">\n<p class=\"import-Normal\" style=\"text-align: center\">Downward facing, tear-drop shaped nostrils, close together<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Arboreal and more terrestrial taxa<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">On average, largest primates<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">On average, most sexually dimorphic taxonomic group<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">2:1:2:3 dental formula<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">All trichromatic<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<caption>Figure 6.41b: Characteristics used to distinguish between the two Catarrhini superfamilies. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\">Catarrhini at a glance (Figure 5.40)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>. [Includes <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Duskyleafmonkey1.jpg\">Duskyleafmonkey1<\/a> by <a href=\"https:\/\/www.the-ninth.com\/about\">Robertpollai<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by\/3.0\/at\/deed.en\">CC BY 3.0 AT<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Male_Bornean_Orangutan_-_Big_Cheeks.jpg\">Male Bornean Orangutan - Big Cheeks<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/8749778@N06\">Eric Kilby<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\">CC BY-SA 2.0<\/a>.]<\/caption>\n<thead>\n<tr>\n<td class=\"a5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong><img class=\"alignnone\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image42-1.jpg\" alt=\"Dusky leaf monkey\" width=\"248\" height=\"186\" \/><\/strong><strong>Superfamily Cercopithecoidea<\/strong><\/p>\n<\/td>\n<td class=\"a5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong><img class=\"alignnone\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image43-1.jpg\" alt=\"Orangutan\" width=\"274\" height=\"183\" \/><\/strong><strong>Superfamily Hominoidea<\/strong><\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"a5-R\">\n<td class=\"a5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Wide geographic distribution<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Bilophodont molars<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Ischial callosities<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Reproduce every 1\u20132 years<\/p>\n<\/td>\n<td class=\"a5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Tropical forests of Africa and Asia<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Y-5 molars<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Adaptations for brachiation<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Reproduce every 4\u20139 years<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h4 class=\"import-Normal\"><em>Family <\/em>Hylobatidae <em>of Southeast Asia<\/em><\/h4>\n<figure style=\"width: 441px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image44-1.jpg\" alt=\"Siamang with outstretched arms.\" width=\"441\" height=\"294\" \/><figcaption class=\"wp-caption-text\">Figure 6.42: Siamangs are the largest of the Hylobatidae family. They are all black with a throat sac that can become inflated to give out loud calls. Credit: <a href=\"https:\/\/www.flickr.com\/photos\/suneko\/373310729\/\">Shout (373310729)<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/suneko\/\">su neko<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/\">CC BY-SA 2.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">The number of genera in this group has been changing in recent years, but the taxa broadly encompasses gibbons and siamangs. Both are found across Southeast Asian tropical forests. Gibbons weigh, on average, about 13 pounds and tend to be more frugivorous, whereas siamangs are larger than gibbons and also more folivorous. Unlike the larger-bodied apes (orangutans, chimps, bonobos, and gorillas) who make nests to sleep in every night, gibbons and siamangs will develop callused patches on their ischium resembling ischial callosities. Gibbon species are quite variable in their colouration and markings, while siamangs are all black with big throat sacs that are used in their exuberant vocalizations (Figure 6.42). Both gibbons and siamangs live in pairs with very little sexual dimorphism, although males and females do differ in colouration in some gibbon species.<\/p>\n<h4 class=\"import-Normal\">Pongo<em> of Southeast Asia<\/em><\/h4>\n<p class=\"import-Normal\">The Genus <em>Pongo <\/em>refers to orangutans. These large red apes are found in Southeast Asia, with the two well-known species each living on the islands of Borneo and Sumatra. A third, very rare species, was recently discovered in Southern Sumatra (Nater Et al. 2017). Orangutans are highly frugivorous but will supplement their diet with leaves and bark when fruit is less available. As mentioned earlier, orangutans are the only diurnal, solitary taxon among primates and are extremely slow to reproduce, producing only one offspring about every seven to nine years. They are highly sexually dimorphic (Figure 6.43 a &amp; b), with fully developed, \u201cflanged\u201d males being approximately twice the size of females. These males have large throat sacs; long, shaggy coats; and cheek flanges. The skulls of male orangutans often feature a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1434\">sagittal crest<\/a><\/strong>, which is believed to function as additional attachment area for chewing muscles as well as a trait used in sexual competition (Balolia, Soligo, &amp; Wood 2017). An unusual feature of orangutan biology is <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1436\">male bimaturism<\/a><\/strong>. Male orangutans are known to delay maturation until one of the more dominant, flanged males disappears. The males that delay maturation are called \u201cunflanged\u201d males, and they can remain in this state for their entire life. Unflanged males resemble females in their size and appearance and will sneak copulations with females while avoiding the bigger, flanged males. Flanged and unflanged male orangutans represent alternative reproductive strategies, both of which successfully produce offspring (Utami Et al. 2002).<\/p>\n<p>&nbsp;<\/p>\n<\/div>\n<figure id=\"attachment_181-9\" aria-describedby=\"caption-attachment-181-9\" style=\"width: 1900px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-180 size-full\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/5.43.jpg\" alt=\"a. Female orangutan with infant. b. Male orangutan in a tree.\" width=\"1900\" height=\"800\" \/><figcaption id=\"caption-attachment-181-9\" class=\"wp-caption-text\">Figure 6.43: (a) A female orangutan eating fruit with her infant nearby and (b) a flanged adult male eating leaves. Male orangutans are about twice the size of females and have a longer coat length, cheek flanges, and throat sac. Credit: 6.43a. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Orang_Utan_(Pongo_pygmaeus)_female_with_baby_(8066259067).jpg\">Orang Utan (Pongo pygmaeus) female with baby (8066259067)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/65695019@N07\">Bernard DUPONT<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/\">CC BY-SA 2.0 Licence<\/a>. 6.43b. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Orangutan_-Zoologischer_Garten_Berlin-8a.jpg\">Orangutan -Zoologischer Garten Berlin-8a<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/37088680@N03\">David Forsman<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/\">CC BY 2.0 License<\/a>.<\/figcaption><\/figure>\n<div class=\"learning-objectives\">\n<h4 class=\"import-Normal\">Gorilla <em>of Africa<\/em><\/h4>\n<p class=\"import-Normal\">There are several species of gorillas that can be found across Central Africa. Gorilla males, like orangutan males, are about twice the size of female gorillas (Figures 6.44a &amp; b). When on the ground, gorillas use a form of quadrupedalism called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1438\">knuckle-walking<\/a><\/strong>, wherein the fingers are curled under and the weight is carried on the knuckles. Male gorillas have a large sagittal crest and large canines compared with females. Adult male gorillas are often called \u201csilverbacks\u201d because when they reach about twelve to thirteen years old, the hair on their backs turns silvery grey. Gorillas typically live in groups of one male and several females. Gorillas are considered folivorous, although some species can be more frugivorous depending on fruit seasonality (Remis 1997).<\/p>\n<\/div>\n<figure id=\"attachment_181-10\" aria-describedby=\"caption-attachment-181-10\" style=\"width: 1900px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-181 size-full\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/5.44.jpg\" alt=\"a. Female gorilla with offspring. b. Male gorilla.\" width=\"1900\" height=\"800\" \/><figcaption id=\"caption-attachment-181-10\" class=\"wp-caption-text\">Figure 6.44: (a) A female gorilla with her two offspring and (b) a silverback adult male. Male gorillas are about twice the size of females. They also differ from females in having a large sagittal crest and a silver back, which appears as they mature. Credit: 6.44a. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Enzo_naomi_echo.jpg\">Enzo naomi echo<\/a> by Zoostar is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/3.0\/legalcode\">CC BY 3.0 License<\/a>. 6.44b. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Male_gorilla_in_SF_zoo.jpg\">Male gorilla in SF zoo<\/a> by Brocken Inaglory is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<div class=\"learning-objectives\">\n<h4 class=\"import-Normal\">Pan<em> of Africa<\/em><\/h4>\n<figure style=\"width: 252px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image49-1.jpg\" alt=\"Bonobo looks away from the camera.\" width=\"252\" height=\"222\" \/><figcaption class=\"wp-caption-text\">Figure 6.45: Bonobo (Pan paniscus). You can see the distinctive hair-part on this bonobo. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Bonobo_male_Jasongo_15yo_Twycross_582a_(2014_11_14_01_04_18_UTC).jpg\">Bonobo male Jasongo 15yo Twycross 582a (2014 11 14 01 04 18 UTC)<\/a> by William H. Calvin is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<p>The Genus <em>Pan <\/em>includes two species: <em>Pan troglodytes <\/em>(the common chimpanzee) and <em>Pan paniscus <\/em>(the bonobo). These species are separated by the Congo River, with chimpanzees ranging across West and Central Africa and bonobos located in a restricted area south of the Congo River. Chimpanzees and bonobos both have broad, largely frugivorous diets.The two species differ morphologically in that bonobos are slightly smaller, have their hair parted down the middle of their foreheads, and are born with dark faces (Figure 6.45). In contrast, chimpanzees do not have the distinctive parted hair and are born with light faces that darken as they mature (Figure 6.46). Chimpanzees and bonobos live in a grouping called a fission-fusion community, which you will learn more about in Chapter 6. Both species are moderately sexually dimorphic, with males about 20% larger than females. When on the ground, chimpanzees and bonobos knuckle-walk like gorillas do.<\/p>\n<figure style=\"width: 418px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image50-1.jpg\" alt=\"Female chimpanzee with offspring in a tree.\" width=\"418\" height=\"278\" \/><figcaption class=\"wp-caption-text\">Figure 6.46: A common chimpanzee (Pan troglodytes) female (centre) and her offspring. Note the pink face of the youngest individual. Bonobos are born with dark-skinned faces, but chimpanzees are born with pink faces that darken with age. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Chimpanzees_in_Uganda_(5984913059).jpg\">Chimpanzees in Uganda (5984913059)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/57424551@N06\">USAID Africa Bureau<\/a> uploaded by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Elitre\">Elitre<\/a> is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\">public domain<\/a>.<\/figcaption><\/figure>\n<h4 class=\"import-Normal\">Homo<\/h4>\n<p class=\"import-Normal\">The last member of the Hominoidea to discuss is our own taxon, Genus <em>Homo<\/em>. Later chapters will discuss the many extinct species of <em>Homo<\/em>, but today there is only one living species of <em>Homo, <\/em>our own species, <em>sapiens<\/em>. While it is interesting to focus on how humans differ from apes in many aspects of our morphology, behaviour, and life history, one objective of this chapter, and of biological anthropology in general, is to understand our place in nature. This means looking for aspects of human biology that link us to the taxonomic diversity we have discussed. To that end, here we will focus on similarities humans share with other hominoids.<\/p>\n<p class=\"import-Normal\">Like other hominoids, humans lack a tail and possess upper-body adaptations for brachiation. While our lower body has been modified for a bipedal gait, we are still able to swing from branches and throw a baseball, all thanks to our mobile shoulder joint. Humans, like other hominoids, also have a Y-5 cusp pattern on our molars. All hominoids, including humans, have an extended life history, taking time to grow and develop, and reproducing slowly over a long life span. Lastly, while humans show a great deal of variation across cultures, many human societies show tendencies for female dispersal (Burton Et al. 1996).<\/p>\n<p class=\"import-Normal\">Among the hominoids, humans show particular affinities with other members of the African Clade, <em>Pan <\/em>and <em>Gorilla<\/em>. Humans share over 96% of our DNA with gorillas (Scally Et al. 2012), and over 98% with <em>Pan <\/em>(Ebersberger Et al. 2002). Even without this strong genetic evidence, the African Clade of hominoids share many morphological similarities, including having wide-set eye sockets and backward-sweeping cheekbones. Today, <em>Pan<\/em> and <em>Gorilla<\/em> knuckle-walk when on the ground, and it has been suggested the last common ancestor of chimpanzees, bonobos, gorillas, and humans did as well (Richmond, Begun, &amp; Strait 2001). Further, humans, chimpanzees, and bonobos all live in fission-fusion social groups characterized by shared behaviours, like male cooperation in hunting and territoriality, as well as tool use.<\/p>\n<div class=\"textbox\">\n<h2 class=\"import-Normal\">Special Topic: Primates in Culture and Religion<\/h2>\n<p class=\"import-Normal\">One of the best parts of teaching anthropology for me is getting to spend time watching primates at zoos. What I also find interesting is watching people watch primates. I have very often heard a parent and child walk up to a chimpanzee enclosure and exclaim \u201cLook at the monkeys!\u201d The parent and child often don\u2019t know that a chimpanzee is not a monkey, nor are they likely to know that chimpanzees share more than 98% of their DNA with us. What strikes me as significant is that, although most people do not know the difference between a monkey, an ape, and a lemur, they nonetheless recognize something in the animals as being similar to themselves. In fact, recognition of similarities between humans and other primates is very ancient, dating back far earlier than Linnaeus. For many of us, we only ever get to see primates in zoos and animal parks, but in many areas of the world, humans have coexisted with these animals for thousands of years. In areas where humans and primates have a long, shared history, nonhuman primates often play key roles in creation myths and cultural symbolism.<\/p>\n<p class=\"import-Normal\">Hamadryas baboons feature significantly in Ancient Egyptian iconography. Ancient Egyptian deities and beliefs transformed over time, as did the role of hamadryas baboons. Early on, baboons were thought to represent dead ancestors, and one monkey deity, called Babi or Baba, was thought to feed off of dead souls. Later, baboons became the totem animal for Thoth, the deity of science, writing, wisdom, and measurement, who also wrote the Book of the Dead. Sunbathing hamadryas baboons led ancient Egyptians to associate them with Ra, the sun god, who was the son of Thoth. During mummification, human organs were removed and put into canopic jars, one of which was topped with the head of the baboon-headed god, Hapi. Hamadryas baboons were also often kept as pets, as depicted in hieroglyphics, and occasionally mummified as well.<\/p>\n<p class=\"import-Normal\">On Madagascar, indris and aye-ayes play roles in the creation myths and omens of local people.There are many myths regarding the origins of indris and their relationship to humans, including one where two brothers living in the forest separated, with one brother leaving the forest and becoming a human while the other stayed in the forest to become the indri. Like humans, indris have long legs, no tail, and upright posture. They are considered sacred and are therefore protected. Unfortunately, the aye-aye is not treated with the same reverence. Because of their unusual appearance (see Figure 6.15), aye-ayes are seen as omens of death.They are usually killed when encountered because it is believed that someone will die if an aye-aye points at them.<\/p>\n<p class=\"import-Normal\">In India, monkeys play a key role in the Hindu religion. Hanuman, who resembles a monkey, is a key figure in the Ramayana. Hanuman is thought to be a guardian deity, and so local monkeys like Hanuman langurs and macaques are protected in India (Figure 6.47). In Thailand, where Hinduism is also practiced, the Hindu reverence for monkeys extends to \u201cmonkey feasts,\u201d where large quantities of food are spread out in gratitude to the monkeys for bringing good fortune.<\/p>\n<figure style=\"width: 308px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image51-1.jpg\" alt=\"Three macaques outside a temple in India.\" width=\"308\" height=\"261\" \/><figcaption class=\"wp-caption-text\">Figure 6.47: Because of important monkey-like figures in the Hindu religion, macaques are protected in India and often live near temples where they are fed by local peoples. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Macaque_India_4.jpg\">Macaque India 4<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Mosmas\">Thomas Schoch<\/a> (<a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Mosmas\">Mosmas<\/a>) is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">The people of Japan have coexisted with Japanese macaques for thousands of years, and so monkeys play key roles in both of the major Japanese religions. In the Shinto religion, macaques are thought of as messengers between the spirit world and humans, and monkey symbols are thought to be good luck. The other major religion in Japan is Buddhism, and monkeys play a role in symbolism of this religion as well. The \u201cThree Wise Monkeys\u201d who see no evil, speak no evil, and hear no evil derive from Buddhist iconography of monkeys.<\/p>\n<p class=\"import-Normal\">In Central and South America, monkeys feature often in Mayan and Aztec stories. In the Mayan creation story, the Popol Vuh, the \u201chero brothers,\u201d are actually a howler monkey and a spider monkey, who represent ancestors of humans in the story. In the Aztec religion, spider monkeys are associated with the god of arts, pleasure, and playfulness. A spider monkey is also represented in a Peruvian Nazca geoglyph, a large design made on the ground by moving rocks.<\/p>\n<p class=\"import-Normal\">In many of these regions today, the relationships between humans and nonhuman primates are complicated. The bushmeat and pet trades make these animals valuable at the expense of many animals\u2019 lives, and in some areas, nonhuman primates have become pests who raid crop fields and consume valuable foods. All of this has led to the development of a new subarea of anthropology called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1440\">Ethnoprimatology<\/a><\/strong>, which involves studying the political, economic, symbolic, and practical relationships between humans and nonhuman primates.This field highlights the particular challenges for humans of having to coexist with animals with whom we share so much in common. It also provides insight into some of the challenges facing primate conservation efforts (see Appendix B: Primate Conservation).<\/p>\n<\/div>\n<h2 class=\"import-Normal\">Summary<\/h2>\n<p class=\"import-Normal\">The Order Primates is a diverse and fascinating group of animals united in sharing a suite of characteristics\u2014visual specialization, grasping hands and feet, large brains, and extended life histories\u2014that differentiates us from other groups of mammals. In this chapter, we surveyed the major taxonomic groups of primates, discussing where humans fit among our close relatives as well as discovering that primates are interesting animals in their own right. We discussed a range of key traits used to distinguish between the many taxa of living primates, including dietary, locomotor, and behavioural characteristics. Because of our long, shared evolutionary history with these animals, nonhuman primates provide a crucial resource for understanding our current biology. In Chapter 7, you will discover the fascinating and complex social behaviours of nonhuman primates, which provide further insight into our evolutionary biology.<\/p>\n<\/div>\n<h2>Expand your view<\/h2>\n<p>For a deeper look into primate conservation and contemporary issues of endangerment\/extinction see <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/appendix-b-primate-conservation\/\">Appendix B<\/a><\/p>\n<p>&nbsp;<\/p>\n<div class=\"learning-objectives\">\n<div class=\"textbox shaded\">\n<h2 class=\"import-Normal\">Review Questions<\/h2>\n<ul>\n<li class=\"import-Normal\">Why does the field of anthropology, a field dedicated to the study of humans, include the study of nonhuman animals? What can we learn from nonhuman primates?<\/li>\n<li class=\"import-Normal\">Why is it important to try to place taxa into a clade classification rather than groupings based on grade? Can you think of an example?<\/li>\n<li class=\"import-Normal\">One of the important goals of an introductory biological anthropology course is to teach you about your place in nature. What is the full taxonomic classification of humans, and what are some of the traits we have of each of these categories?<\/li>\n<li class=\"import-Normal\">When you have seen primates in person, did you observe any facial expressions, behaviours, or physical traits that seemed familiar to you? If so, which ones and why?<\/li>\n<li class=\"import-Normal\">Draw out a tree showing the major taxonomic group of primates described here, making sure to leave room in between each level. Underneath each taxon, list some of the key features of this group so that you can compare traits between groups.<\/li>\n<\/ul>\n<\/div>\n<h2 class=\"import-Normal\">Key Terms<\/h2>\n<p class=\"import-Normal\"><strong>Activity pattern<\/strong>: Refers to the time of day an animal is typically active.<\/p>\n<p class=\"import-Normal\"><strong>African clade<\/strong>: A grouping that includes gorillas, chimpanzees, bonobos, humans, and their extinct relatives.<\/p>\n<p class=\"import-Normal\"><strong>Analogy<\/strong>: When two or more taxa exhibit similar traits that have evolved independently, the similar traits evolve due to similar selective pressures. (Also sometimes called convergent evolution, parallel evolution, or homoplasy.)<\/p>\n<p class=\"import-Normal\"><strong>Ancestral trait<\/strong>: A trait that has been inherited from a distant ancestor.<\/p>\n<p class=\"import-Normal\"><strong>Arboreal<\/strong>: A descriptor for an organism that spends most of its time in trees.<\/p>\n<p class=\"import-Normal\"><strong>Asian clade<\/strong>: A grouping that includes orangutang and their extinct relatives.<\/p>\n<p class=\"import-Normal\"><strong>Bilophodont<\/strong>: Molar pattern of cercopithecoid monkeys in which there are usually four cusps that are arranged in a square pattern and connected by two ridges.<\/p>\n<p class=\"import-Normal\"><strong>Bipedalism<\/strong>: Walking on two legs.<\/p>\n<p class=\"import-Normal\"><strong>Brachiation<\/strong>: A form of locomotion in which the organism swings below branches using the forelimbs.<\/p>\n<p class=\"import-Normal\"><strong>Bunodont<\/strong>: Low, rounded cusps on the cheek teeth.<\/p>\n<p class=\"import-Normal\"><strong>Canines<\/strong>: In most primates, these are the longest of the teeth, often conical in shape and used as a weapon against predators or others of their species.<\/p>\n<p class=\"import-Normal\"><strong>Cathemeral<\/strong>: Active throughout the 24-hour period.<\/p>\n<p class=\"import-Normal\"><strong>Clade<\/strong>: A grouping based on ancestral relationships; a branch of the evolutionary tree.<\/p>\n<p class=\"import-Normal\"><strong>Cusps<\/strong>: The bumps on the chewing surface of the premolars and molars, which can be quite sharp in some species.<\/p>\n<p class=\"import-Normal\"><strong>Dental formula<\/strong>: The number of each type of tooth in one quadrant of the mouth, written as number of incisors: canines: premolars: molars.<\/p>\n<p class=\"import-Normal\"><strong>Derived trait<\/strong>: A trait that has been recently modified, most helpful when assigning taxonomic classification.<\/p>\n<p class=\"import-Normal\"><strong>Diastema<\/strong>: A space between the teeth, usually for large canines to fit when the mouth is closed.<\/p>\n<p class=\"import-Normal\"><strong>Dichromatic<\/strong>: Being able to see only blues and greens.<\/p>\n<p class=\"import-Normal\"><strong>Diurnal<\/strong>: Active during the day.<\/p>\n<p class=\"import-Normal\"><strong>Dry nose<\/strong>: The nose and upper lip are separated and the upper lip can move independently; sometimes referred to as a \u201chairy\u201d or \u201cmobile\u201d upper lip.<\/p>\n<p class=\"import-Normal\"><strong>Ethnoprimatology<\/strong>: A subarea of anthropology that studies the complexities of human-primate relationships in the modern environment.<\/p>\n<p class=\"import-Normal\"><strong>Evolutionary trade-off<\/strong>: When an organism, which is limited in the time and energy it can put into aspects of its biology and behaviour, is shaped by natural selection to invest in one adaptation at the expense of another.<\/p>\n<p class=\"import-Normal\"><strong>Faunivorous<\/strong>: Having a diet consisting entirely of animal matter: insects, eggs, lizards, etc.<\/p>\n<p class=\"import-Normal\"><strong>Folivore<\/strong>: Having a diet consisting primarily of leaves.<\/p>\n<p class=\"import-Normal\"><strong>Fovea<\/strong>: A depressed area in the retina at the back of the eye containing a concentration of cells that allow one to focus on objects very close to one\u2019s face.<\/p>\n<p class=\"import-Normal\"><strong>Frugivore<\/strong>: Having a diet consisting primarily of fruit.<\/p>\n<p class=\"import-Normal\"><strong>Generalized trait<\/strong>: A trait that is useful for a wide range of tasks.<\/p>\n<p class=\"import-Normal\"><strong>Grade<\/strong>: A grouping based on overall similarity in lifestyle, appearance, and behaviour.<\/p>\n<p class=\"import-Normal\"><strong>Grooming claw<\/strong>: A claw present on the second pedal digit in strepsirrhines.<\/p>\n<p class=\"import-Normal\"><strong>Gummivore<\/strong>: Having a diet consisting primarily of gums and saps.<\/p>\n<p class=\"import-Normal\"><strong>Heterodont<\/strong>: Having different types of teeth.<\/p>\n<p class=\"import-Normal\"><strong>Homology<\/strong>: When two or more taxa share characteristics because they inherited them from a common ancestor.<\/p>\n<p class=\"import-Normal\"><strong>Hone<\/strong>: When primates sharpen their canines by wearing them on adjacent teeth.<\/p>\n<p class=\"import-Normal\"><strong>Incisors<\/strong>: The spatula-shaped teeth at the front of the mouth.<\/p>\n<p class=\"import-Normal\"><strong>Insectivore<\/strong>: Having a diet consisting primarily of insects.<\/p>\n<p class=\"import-Normal\"><strong>Ischial callosities<\/strong>: Modified seat bones of the pelvis that are flattened and over which calluses form; function as seat pads for sitting and resting atop branches.<\/p>\n<p class=\"import-Normal\"><strong>Knuckle-walking<\/strong>: A form of quadrupedal movement used by <em>Gorilla<\/em> and <em>Pan<\/em> when on the ground, wherein the front limbs are supported on the knuckles of the hands.<\/p>\n<p class=\"import-Normal\"><strong>Life history<\/strong>: Refers to an organism\u2019s pace of growth, reproduction, lifespan, etc.<\/p>\n<p class=\"import-Normal\"><strong>Locomotion<\/strong>: How an organism moves around.<\/p>\n<p class=\"import-Normal\"><strong>Male bimaturism<\/strong>: Refers to the alternative reproductive strategies in orangutans in which males can delay maturation, sometimes indefinitely, until a fully mature, \u201cflanged\u201d male disappears.<\/p>\n<p class=\"import-Normal\"><strong>Molars<\/strong>: The largest teeth at the back of the mouth; used for chewing. In primates, these teeth usually have between three and five cusps.<\/p>\n<p class=\"import-Normal\"><strong>Monochromatic<\/strong>: Being able to see only in shades of light to dark, no colour.<\/p>\n<p class=\"import-Normal\"><strong>Monomorphic<\/strong>: When males and females of a species do not exhibit significant sexual dimorphism.<\/p>\n<p class=\"import-Normal\"><strong>Natal coat<\/strong>: Refers to the contrasting fur colour of baby leaf monkeys compared to adults.<\/p>\n<p class=\"import-Normal\"><strong>Nocturnal<\/strong>: Active at night.<\/p>\n<p class=\"import-Normal\"><strong>Olecranon process<\/strong>: Bony projection at the elbow end of the ulna.<\/p>\n<p class=\"import-Normal\"><strong>Opposable thumb <\/strong>or <strong>opposable big toe<\/strong>: Having thumbs and toes that go in a different direction from the rest of the fingers, allows for grasping with hands and feet.<\/p>\n<p class=\"import-Normal\"><strong>Pentadactyly<\/strong>: Having five digits or fingers and toes.<\/p>\n<p class=\"import-Normal\"><strong>Polymorphic colour vision<\/strong>: A system in which individuals of a species vary in their abilities to see colour. In primates, it refers to males being dichromatic and females being either trichromatic or dichromatic.<\/p>\n<p class=\"import-Normal\"><strong>Postorbital bar<\/strong>: A bony ring that surrounds the eye socket, open at the back.<\/p>\n<p class=\"import-Normal\"><strong>Postorbital closure\/plate<\/strong>: A bony plate that provides protection to the side and back of the eye.<\/p>\n<p class=\"import-Normal\"><strong>Prehensile tail<\/strong>: A tail that is able to hold the full body weight of an organism, which often has a tactile pad on the underside of the tip for improved grip.<\/p>\n<p class=\"import-Normal\"><strong>Premolars<\/strong>: Smaller than the molars, used for chewing. In primates, these teeth usually have one or two cusps.<\/p>\n<p class=\"import-Normal\"><strong>Quadrupedalism<\/strong>: Moving around on all fours.<\/p>\n<p class=\"import-Normal\"><strong>Rhinariums<\/strong>: Wet noses; resulting from naked skin of the nose which connects to the upper lip and smell-sensitive structures along the roof of the mouth.<\/p>\n<p class=\"import-Normal\"><strong>Sagittal crest<\/strong>: A bony ridge along the top\/middle of the skull, used for attachment of chewing muscles.<\/p>\n<p class=\"import-Normal\"><strong>Scent marking<\/strong>: The behaviour of rubbing scent glands or urine onto objects as a way of communicating with others.<\/p>\n<p class=\"import-Normal\"><strong>Semi-brachiation<\/strong>: A form of locomotion in which an organism swings below branches using a combination of forelimbs and prehensile tail.<\/p>\n<p class=\"import-Normal\"><strong>Sexually dimorphic<\/strong>: When a species exhibits sex differences in morphology, behaviour, hormones, and\/or colouration.<\/p>\n<p class=\"import-Normal\"><strong>Shearing crests<\/strong>: Sharpened ridges that connect cusps on a bilophodont molar.<\/p>\n<p class=\"import-Normal\"><strong>Specialized trait<\/strong>: A trait that has been modified for a specific purpose.<\/p>\n<p class=\"import-Normal\"><strong>Styloid process of ulna<\/strong>: A bony projection of the ulna at the end near the wrist.<\/p>\n<p class=\"import-Normal\"><strong>Tactile pads<\/strong>: Sensitive skin at the fingertips for sense of touch. Animals with a prehensile tail have a tactile pad on the underside of the tail as well.<\/p>\n<p class=\"import-Normal\"><strong>Tapetum lucidum<\/strong>: Reflecting layer at the back of the eye that magnifies light.<\/p>\n<p class=\"import-Normal\"><strong>Terrestrial<\/strong>: A descriptor for an organism that spends most of its time on the ground.<\/p>\n<p class=\"import-Normal\"><strong>Tetrachromatic<\/strong>: Having the ability to see reds, yellows, blues, greens, and ultraviolet.<\/p>\n<p class=\"import-Normal\"><strong>Tooth comb<\/strong> or <strong>dental comb<\/strong>: A trait of the front, lower teeth of strepsirrhines in which, typically, the four incisors and canines are long and thin and protrude outward.<\/p>\n<p class=\"import-Normal\"><strong>Trichromatic colour vision<\/strong>: Being able to distinguish yellows and reds in addition to blues and greens.<\/p>\n<p class=\"import-Normal\"><strong>Vertical clinging and leaping<\/strong>: A locomotor pattern in which animals are oriented upright while clinging to vertical branches, push off with hind legs, and land oriented upright on another vertical branch.<\/p>\n<p class=\"import-Normal\"><strong>Y-5 molar<\/strong>: Molar cusp pattern in which five molar cusps are separated by a \u201cY\u201d-shaped groove pattern.<\/p>\n<h2 class=\"import-Normal\">For Further Exploration<\/h2>\n<p class=\"import-Normal\"><a href=\"https:\/\/animaldiversity.org\/accounts\/Primates\/specimens\/\">Animal Diversity Web<\/a>. This website is hosted by the Zoology Department at the University of Michigan. It has photographs of skulls, teeth, hands, arms, and feet of many primate species.<\/p>\n<p class=\"import-Normal\"><a href=\"https:\/\/www.eskeletons.org\">eSkeletons<\/a>. This website is hosted by the Department of Anthropology at University of Texas, Austin. It is an interactive website where you can compare specific bones from different species of primates.<\/p>\n<p class=\"import-Normal\">Fleagle, John G. 2013. <em>Primate Adaptation and Evolution<\/em>. Third edition. San Diego: Academic Press.<\/p>\n<p class=\"import-Normal\">Fuentes, Agust\u00edn, and Kimberley J. Hockings. 2010. \u201cThe Ethnoprimatological Approach in Primatology.\u201d <em>American Journal of Primatology<\/em> 72 (10): 841\u2013847.<\/p>\n<p class=\"import-Normal\">Rowe, Noel. 1996. <em>Pictorial Guide to the Living Primates<\/em>. Charlestown, RI: Pogonias Press.<\/p>\n<p class=\"import-Normal\">Whitehead, Paul F., William K. Sacco, and Susan B. Hochgraf. 2005. <em>A Photographic Atlas for Physical Anthropology<\/em>. Englewood, CO: Morton Publishing.<\/p>\n<h2>References<\/h2>\n<p class=\"import-Normal\">Balolia, Katharine L., Christophe Soligo, and Bernard Wood. 2017. \u201cSagittal Crest Formation in Great Apes and Gibbons.\u201d <em>Journal of Anatomy<\/em> 230 (6): 820\u2013832.<\/p>\n<p class=\"import-Normal\">Bininda-Emonds, Olaf R., Marcel Cardillo, Kate E. Jones, Ross D. E. MacPhee, Robin M. D. Beck, Richard Grenyer, Samantha A. Price, Rutger A. Vos, John L. Gittleman, and Andy Purvis. 2007. \u201cThe Delayed Rise of Present-Day Mammals.\u201d <em>Nature<\/em> 446 (7135): 507\u2013512.<\/p>\n<p class=\"import-Normal\">Burton, Michael L., Carmella C. Moore, John W. M. Whiting, A. Kimball Romney, David F. Aberle, Juan A. Barcelo, Malcolm M. Dow, et al. 1996. \u201cRegions Based on Social Structure.\u201d <em>Current Anthropology<\/em> 37 (1): 87\u2013123.<\/p>\n<p class=\"import-Normal\">Chivers, David J., and C. M. Hladik. 1980. \u201cMorphology of the Gastrointestinal Tract in Primates: Comparisons with Other Mammals in Relation to Diet.\u201d <em>Journal of Morphology<\/em> 166 (3): 337\u2013386.<\/p>\n<p class=\"import-Normal\">Clutton-Brock, T. H., and Paul H. Harvey. 1980. \u201cPrimates, Brains, and Ecology.\u201d <em>Journal of Zoology<\/em> 190 (3): 309\u2013323.<\/p>\n<p class=\"import-Normal\">Dunbar, Robin I. M. 1998. \u201cThe Social Brain Hypothesis.\u201d <em>Evolutionary Anthropology<\/em> 6 (5): 178\u2013190.<\/p>\n<p class=\"import-Normal\">Ebersberger, Ingo, Dirk Metzler, Carsten Schwarz, and Svante P\u00e4\u00e4bo. 2002. \u201cGenomewide Comparison of DNA Sequences Between Humans and Chimpanzees.\u201d <em>American Journal of Human Genetics<\/em> 70 (6): 1490\u20131497.<\/p>\n<p class=\"import-Normal\">Jameson, Natalie M., Zhuo-Cheng Hou, Kirstin N. Sterner, Amy Weckle, Morris Goodman, Michael E. Steiper, and Derek E. Wildman. 2011. \u201cGenomic Data Reject the Hypothesis of a Prosimian Primate Clade.\u201d <em>Journal of Human Evolution<\/em> 61 (3): 295\u2013305.<\/p>\n<p class=\"import-Normal\">Kawamura, Shoji, Chihiro Hiramatsu, Amanda D. Melin, Colleen M. Schaffner, Filippo Aureli, and Linda M. Fedigan. 2012. \u201cPolymorphic Color Vision in Primates: Evolutionary Considerations.\u201d In <em>Post-Genome Biology of Primates<\/em>, edited by H. Irai, H. Imai, and Y. Go, 93\u2013120. Tokyo: Springer.<\/p>\n<p class=\"import-Normal\">Matsui, Atsushi, Felix Rakotondraparany, Isao Munechika, Masami Hasegawa, and Satoshi Horai. 2009. \u201cMolecular Phylogeny and Evolution of Prosimians Based on Complete Sequences of Mitochondrial DNAs.\u201d <em>Gene<\/em> 441 (1\u20132): 53\u201366.<\/p>\n<p class=\"import-Normal\">Nater, Alexander, Maja P. Mattle-Greminger, Anton Nurcahyo, Matthew G. Nowak, Marc de Manuel, Tariq Desai, Colin Groves, et al. 2017. \u201cMorphometric, Behavioral, and Genomic Evidence for a New Orangutan Species.\u201d <em>Current Biology<\/em> 27 (22): 3487\u20133498.<\/p>\n<p class=\"import-Normal\">Pozzi, Luca, Jason A. Hodgson, Andrew S. Burrell, Kirstin N. Sterner, Ryan L. Raaum, and Todd R. Disotell. 2014. \u201cPrimate Phylogenetic Relationships and Divergence Dates Inferred from Complete Mitochondrial Genomes.\u201d <em>Molecular Phylogenetics and Evolution<\/em> 75: 165\u2013183.<\/p>\n<p class=\"import-Normal\">Remis, Melissa J. 1997. \u201cWestern Lowland Gorillas (<em>Gorilla gorilla gorilla<\/em>) as Seasonal Frugivores: Use of Variable Resources.\u201d <em>American Journal of Primatology<\/em> 43 (2): 87\u2013109.<\/p>\n<p class=\"import-Normal\">Richmond, Brian G., David R. Begun, and David S. Strait. 2001. \u201cOrigin of Human Bipedalism: The Knuckle\u2010Walking Hypothesis Revisited.\u201d <em>American<\/em> <em>Journal of Physical Anthropology<\/em> 116 (S33): 70\u2013105.<\/p>\n<p class=\"import-Normal\">Robson, Shannen L., Carel P. van Schaik, and Kristen Hawkes. 2006. \u201cThe Derived Features of Human Life History.\u201d In <em>The Evolution of Human Life History, edited by Kristen Hawkes and Richard R. Paine, <\/em>17\u201344. Santa Fe: SAR Press.<\/p>\n<p class=\"import-Normal\">Scally, Aylwyn, Julien Y. Dutheil, LaDeana W. Hillier, Gregory E. Jordan, Ian Goodhead, Javier Herrero, Asger Hobolth, et al. 2012. \u201cInsights into Hominid Evolution from the Gorilla Genome Sequence.\u201d <em>Nature<\/em> 483 (7388): 169\u2013175.<\/p>\n<p class=\"import-Normal\">Schneider, Horacio, and Iracilda Sampaio. 2015. \u201cThe Systematics and Evolution of New World Primates: A Review.\u201d <em>Molecular Phylogenetics and Evolution<\/em> 82 (B): 348\u2013357.<\/p>\n<p class=\"import-Normal\">Setchell, Joanna M., Phyllis C. Lee, E. Jean Wickings, and Alan F. Dixson. 2001. \u201cGrowth and Ontogeny of Sexual Size Dimorphism in the Mandrill (<em>Mandrillus sphinx<\/em>).\u201d <em>American Journal of Physical Anthropology<\/em> 115 (4): 349\u2013360.<\/p>\n<p class=\"import-Normal\">Utami, Sri Suci, Beno\u00eet Goossens, Michael W. Bruford, Jan R. de Ruiter, and Jan A. R. A. M. van Hooff. 2002. \u201cMale Bimaturism and Reproductive Success in Sumatran Orang-utans.\u201d <em>Behavioral Ecology<\/em> 13 (5): 643\u2013652.<\/p>\n<p class=\"import-Normal\">Vasey, Natalie. 2006. \u201cImpact of Seasonality and Reproduction on Social Structure, Ranging Patterns, and Fission\u2013Fusion Social Organization in Red Ruffed Lemurs.\u201d In <em>Lemurs: Ecology and Adaptation<\/em>, edited by Lisa Gould and Michelle L. Sauther, 275\u2013304. New York: Springer.<\/p>\n<p class=\"import-Normal\">Wright, Patricia C. 1999. \u201cLemur Traits and Madagascar Ecology: Coping with an Island Environment.\u201d <em>American Journal of Physical Anthropology<\/em> 110 (S29): 31\u201372.<\/p>\n<h2>Acknowledgements<\/h2>\n<p class=\"import-Normal\">The author would very much like to thank the editors for the opportunity to contribute to this textbook, along with anonymous reviewers who provided useful feedback on earlier drafts of this chapter. She would particularly like to thank Karin Enstam Jaffe for her support and encouragement during the writing of this chapter and its revision. Most of all, the author would like to thank all of the Introduction to Biological Anthropology students that she has had over the years who have listened to her lecture endlessly on these animals that she finds so fascinating and who have helped her to hone her pedagogy in a field that she loves.<\/p>\n<\/div>\n<\/div>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1695_1855\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1695_1855\"><div tabindex=\"-1\"><div class=\"__UNKNOWN__\">\n<div class=\"textbox\">\n<p>Learn more about <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/about-the-authors\/\">authors and editors<\/a>,<a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/student-contributors\/\"> Hess' student contributions<\/a>, and <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/versioning-history\/\">versioning history<\/a>.<\/p>\n<\/div>\n<div class=\"textbox textbox--learning-objectives\">\n<header class=\"textbox__header\">\n<h2 class=\"textbox__title\">Learning Objectives<\/h2>\n<\/header>\n<div class=\"textbox__content\">\n<ul>\n<li class=\"import-Normal\">Describe how studying nonhuman primates is important in anthropology.<\/li>\n<li class=\"import-Normal\">Compare two ways of categorizing taxa: grades and clades.<\/li>\n<li class=\"import-Normal\">Define different types of traits used to evaluate primate taxa.<\/li>\n<li class=\"import-Normal\">Identify key ways that primates differ from other mammals.<\/li>\n<li class=\"import-Normal\">Distinguish between the major primate taxa using their key characteristics.<\/li>\n<li class=\"import-Normal\">Describe your place in nature by learning your taxonomic classification.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<p class=\"import-Normal\">You may be wondering why a field dedicated to the study of humans includes discussions of nonhuman animals. Our primary goal in biological anthropology is to understand how humans are similar to and different from the rest of the natural world, why we have the traits we have, and how we got to be the way we are. But to fully grasp our place in nature, we must look to our closest living relatives, the nonhuman primates. In this chapter, we focus on the organization and diversity within the Order Primates.<\/p>\n<h2 class=\"import-Normal\">Studying Primates in Biological Anthropology<\/h2>\n<p class=\"import-Normal\">Primates are one of at least twenty Orders belonging to the Class Mammalia, and probably one of the oldest. One genetic estimate puts the origin of primates at approximately 91 million years ago (mya), predating the extinction of the dinosaurs (Bininda-Emonds Et al. 2007). Today, the Order Primates is a diverse group of animals that includes lemurs and lorises, tarsiers, monkeys, apes, and humans, all of which are united in sharing a suite of anatomical, behavioural, and life history characteristics. While nonhuman primates are fascinating animals in their own right, their close relationship to humans makes them ideal for studying humans via <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_944\">homology<\/a>, <\/strong>looking at traits that are shared between taxa because they inherited the trait from a common ancestor. For example, humans (genus <em>Homo<\/em>) and chimpanzees (genus <em>Pan<\/em>) both share the trait of male cooperation in hunting. This trait\u2014along with many others that chimpanzees and humans share\u2014is likely homologous<em>, <\/em>meaning it was probably passed down from the last common ancestor of <em>Homo<\/em> and <em>Pan, <\/em>which lived about 6\u20138 million years ago.<\/p>\n<p class=\"import-Normal\">Nonhuman primates also make excellent comparators for learning about humans via <strong>analogy<\/strong>. Many nonhuman primates live in environments similar to those in which our ancestors lived and therefore exhibit traits similar to what we see in humans. For example, baboons and humans both have long legs. In humans, this is because about 1.7 million years ago, our ancestors moved into savanna habitats where longer legs helped them move more efficiently over long distances. Baboons, who also live in savanna habitats, independently evolved longer arms and legs for the same reason\u2014to be able to cover more ground, more efficiently. This means that having long legs is an analogous trait in baboons and humans: \u2014that is, this adaptation evolved independently in the two species but for the same purpose. Using homology and analogy, our closest living relatives provide the critical context in which to understand human biology, morphology, and behaviour. It is only by studying how humans compare with our primate relatives that we can fully comprehend our place in nature.<\/p>\n<h3 class=\"import-Normal\"><strong>Ways of Organizing Taxa<\/strong><\/h3>\n<p class=\"import-Normal\">You learned in Chapter 2 about Linnaeus and the hierarchical nature of taxonomic classification. Our goal in classifying taxa is to create categories that reflect clade relationships. A <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1116\">clade<\/a> <\/strong>is a grouping of organisms based on relatedness that reflects a branch of the evolutionary tree. Clade relationships are determined using traits shared by groups of taxa as well as genetic similarities. An example of a clade would be a grouping that includes humans, chimpanzees, bonobos, and gorillas (Figure 6.1). These taxa are in what is referred to as the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1118\">African clade<\/a><\/strong> of hominoids (a taxonomic group you will learn about later in this chapter). The African clade grouping reflects how humans, chimpanzees, bonobos, and gorillas all share a more recent ancestor with each other than any of them do with other species\u2014that is, we are on the same branch of the evolutionary tree. We know members of the African clade are most closely related based on shared morphological traits as well as genetic similarities. Excluded from this grouping is the orangutan, which is considered a member of the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1120\">Asian clade<\/a><\/strong> of hominoids.<\/p>\n<figure style=\"width: 800px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2023\/06\/image1-3.jpg\" alt=\"Diagram shows large-bodied hominoids grouped by grade or clade.\" width=\"800\" height=\"358\" \/><figcaption class=\"wp-caption-text\">Figure 6.1: Grades vs. Clades. A grade grouping of apes places orangutans, gorillas, chimpanzees, and bonobos together based on their similar appearance and lifestyle, but excludes humans. Clade classification is based on shared derived traits and genetic evidence (both reflecting close evolutionary relationships). A clade grouping of apes places humans with gorillas, chimpanzees, and bonobos., whereas orangutans are separated. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\">Grades vs. clades comparison (Figure 5.12)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\">CC BY-NC-SA 4.0 License<\/a>. [Includes <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Orangutan_on_a_tree_(Unsplash).jpg\">Orangutan on a tree (Unsplash)<\/a> by Dawn Armfield, <a href=\"https:\/\/creativecommons.org\/publicdomain\/zero\/1.0\/legalcode\">public domain (CC0 1.0)<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Gorilla_Profile_(17997840570).jpg\">Gorilla Profile (17997840570)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/100915417@N07\">Charlie Marshall<\/a> from Bristol UK, modified (cropped), <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/legalcode\">CC BY 2.0 License<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Chimpanzee_(14679767561).jpg\">Chimpanzee (14679767561)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/120374925@N06\">Magnus Johansson<\/a>, modified (cropped), <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\">CC BY-SA 2.0<\/a>; <a href=\"https:\/\/pixabay.com\/photos\/pointing-finger-hand-pointing-1922074\/\">Pointing finger (1922074)<\/a> by <a href=\"https:\/\/pixabay.com\/users\/truthseeker08-2411480\/\">truthseeker08<\/a>, <a href=\"https:\/\/pixabay.com\/service\/terms\/#license\">Pixabay License<\/a>.]<\/figcaption><\/figure>\n<p class=\"import-Normal\">In contrast, <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1122\">grades<\/a> <\/strong>are groupings that reflect levels of adaptation or overall similarity and not necessarily evolutionary relationships. An example of a grade would be placing orangutans, gorillas, bonobos, and chimpanzees into a group, and excluding humans. Grouping in this way is based on the superficial similarities of the apes in being large-bodied, having lots of body hair, living in tropical forests, climbing and sleeping in trees, and so on. According to these criteria, humans seem to be unusual in that we differ in our morphology, behaviour, and ecology. Separating humans from the large-bodied apes is the system that was used historically. We now know that grouping orangutans, gorillas, bonobos, and chimpanzees and excluding humans does not accurately reflect our true evolutionary relationships. Since our goal in taxonomic classification is to organize animals to reflect their evolutionary relationships, we prefer to use clade classifications.<\/p>\n<h3 class=\"import-Normal\"><strong>Types of Traits<\/strong><\/h3>\n<p class=\"import-Normal\">When evaluating relationships between taxa, we use key traits that allow us to determine which species are most closely related to one another. Traits can be either ancestral or derived. <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1124\">Ancestral traits<\/a><\/strong> are those that a taxon has because it has inherited the trait from a distant ancestor. For example, all primates have body hair because we are mammals and all mammals share an ancestor hundreds of millions of years ago that had body hair. This trait has been passed down to all mammals from a shared ancestor, so all mammals alive today have body hair. <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1126\">Derived traits<\/a><\/strong> are those that have been more recently altered. This type of trait is most useful when we are trying to distinguish one group from another because derived traits tell us which taxa are more closely related to each other. For example, humans walk on two legs.The many adaptations that humans possess that allow us to move in this way evolved after humans split from the Genus <em>Pan<\/em>. This means that when we find fossil taxa that share derived traits for walking on two legs, we can conclude that they are likely more closely related to humans than to chimpanzees and bonobos<em>. <\/em><\/p>\n<p class=\"import-Normal\">There are a couple of other important points about ancestral and derived traits that will become apparent as we discuss primate diversity. First, the terms <em>ancestral<\/em> and <em>derived<\/em> are relative terms, meaning that a trait can be either one depending on the taxa being compared. For example, in the previous paragraph, body hair was used as an example for an ancestral trait among primates. All mammals have body hair because we share a distant ancestor who had this trait. The presence of body hair therefore doesn\u2019t allow you to distinguish whether monkeys are more closely related to apes or lemurs because they all share this trait. However, if we are comparing mammals to birds and fish, then body hair becomes a derived trait of mammals. It evolved after mammals diverged from birds and fish, and it tells us that all mammals are more closely related to each other than they are to birds or fish.The second important point is that very often when one lineage splits into two, one taxon will stay more similar to the last common ancestor in retaining more ancestral traits, whereas the other lineage will usually become more different from the last common ancestor by developing more derived traits. This will become very apparent when we discuss the two suborders of primates, Strepsirrhini and Haplorrhini. When these two lineages diverged, strepsirrhines retained more ancestral traits (those present in the earliest primates) and haplorrhines developed more derived traits (became more different from ancestral primates).<\/p>\n<p class=\"import-Normal\">There are two other types of traits that will be relevant to our discussions here: generalized and specialized traits. <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1128\">Generalized traits<\/a> <\/strong>are those characteristics that are useful for a wide range of things. Having <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1138\">opposable thumbs<\/a><\/strong> that go in a different direction than the rest of your fingers is a very useful, generalized trait. You can hold a pen, grab a branch, peel a banana, or text your friends all thanks to your opposable thumbs! <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1130\">Specialized traits<\/a> <\/strong>are those that have been modified for a specific purpose. These traits may not have a wide range of uses, but they will be very efficient at their job. Hooves in horses are a good example of a specialized trait: they allow horses to run quickly on the ground on all fours. You can think of generalized traits as a Swiss Army knife, useful for a wide range of tasks but not particularly good at any one of them. That is, if you\u2019re in a bind, then a Swiss Army knife can be very useful to cut a rope or fix a loose screw, but if you were going to build furniture or fix a kitchen sink, then you\u2019d want specialized tools for the job. As we will see, most primate traits tend to be generalized.<\/p>\n<h2 class=\"import-Normal\">What Makes Something a Primate?<\/h2>\n<p class=\"import-Normal\">The Order Primates is distinguished from other groups of mammals in having a <em>suite of characteristics<\/em>. This means that there is no individual trait that you can use to instantly identify an animal as a primate; instead, you have to look for animals that possess a collection of traits. What this also means is that each individual trait we discuss may be found in nonprimates, but if you see an animal that has most or all of these traits, there is a good chance it is a primate.<\/p>\n<p class=\"import-Normal\">Primates are most distinguishable from other organisms in traits related to our vision. Our Order relies on vision as a primary sense, which is reflected in many areas of our anatomy and behaviour. All primates have eyes that face forward with convergent (overlapping) visual fields. So if you cover one eye with your hand, you can still see most of the room with your other one. This also means that we cannot see on the sides or behind us as well as some other animals can. In order to protect the sides of the eyes from the muscles we use for chewing, all primates have at least a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1132\">postorbital bar<\/a>, <\/strong>a bony ring around the outside of the eye (Figure 6.2). Primate taxa with more convergent eyes need extra protection, so animals with greater orbital convergence will have a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1134\">postorbital plate<\/a> <\/strong>or<strong> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1136\">postorbital closure<\/a> <\/strong>in addition to the bar (Figure 6.2).The postorbital bar is a derived trait of primates, appearing in our earliest ancestors.<\/p>\n<figure style=\"width: 661px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image2-4.jpg\" alt=\"Skulls of a monkey and lemur viewed from the side and top.\" width=\"661\" height=\"430\" \/><figcaption class=\"wp-caption-text\">Figure 6.2: All primates have bony protection around their eyes. Some have a postorbital bar only (right), but many have full postorbital closure, also called a postorbital plate, that completely protects the back of the eye socket (left). Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\">Postorbital bar\/Postorbital closure (Figure 5.1)<\/a> a derivative work original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\">CC BY-NC-SA 4.0 License<\/a>. [Includes <a href=\"https:\/\/animaldiversity.org\/accounts\/Otolemur_crassicaudatus\/specimens\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Otolemur_crassicaudatus\/lateral\/\">Otolemur crassicaudatus (greater galago)<\/a> by <a href=\"https:\/\/animaldiversity.org\/\">Animal Diversity Web<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\">CC BY-NC-SA 3.0<\/a>; <a href=\"https:\/\/animaldiversity.org\/accounts\/Otolemur_crassicaudatus\/specimens\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Otolemur_crassicaudatus\/dorsal1809\/\">Macaca fascicularis (long-tailed macaque)<\/a> by <a href=\"https:\/\/animaldiversity.org\/\">Animal Diversity Web<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\">CC BY-NC-SA 3.0<\/a>.]<\/figcaption><\/figure>\n<p class=\"import-Normal\">Another distinctive trait of our Order is that many primates have <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1140\">trichromatic color vision<\/a><\/strong>, the ability to distinguish reds and yellows in addition to blues and greens. Birds, fish, and reptiles are <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1142\">tetrachromatic<\/a> <\/strong>(they can see reds, yellows, blues, greens, and even ultraviolet), but most mammals, including some primates, are only <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1144\">dichromatic<\/a> <\/strong>(they see only in blues and greens). It is thought that the nocturnal ancestors of mammals benefited from seeing better at night rather than in colour, and so dichromacy is the ancestral condition for mammals. Trichromatic primates are known to use their colour vision for all sorts of purposes: finding young leaves and ripe fruits, identifying other species, and evaluating signals of health and fertility.<\/p>\n<p class=\"import-Normal\">The primate visual system uses a lot of energy, so primates have compensated by cutting back on other sensory systems, particularly our sense of smell. Compared to other mammals, primates have reduced snouts, another derived trait that appears even in the earliest primate ancestors. There is variation across primate taxa in how much snouts are reduced. Those with a better sense of smell usually have poorer vision than those with a relatively dull sense of smell. The reason for this is that all organisms have a limited amount of energy to spend on running our bodies, so we make <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1146\">evolutionary trade-offs<\/a><\/strong>, as energy spent on one trait cuts back on energy spent on another. So primates with better vision are spending more energy on vision and thus have a poorer smell (and shorter snout), and those who spend less energy on vision will have a better sense of smell (and a longer snout).<\/p>\n<p class=\"import-Normal\">Primates also differ from other mammals in the size and complexity of our brains. On average, primates have brains that are twice as big for their body size when compared to other mammals. Not unexpectedly, the visual centres of the brain are larger in primates and the wiring is different from that in other animals, reflecting our reliance on this sense. The neocortex, which is used for higher functions like consciousness and language in humans, as well as sensory perception and spatial awareness, is also larger in primates relative to other animals. In nonprimates this part of the brain is often smooth, but in primates it is made up of many folds, which increase the surface area. It has been proposed that the more complex neocortex of primates is related to diet, with fruit-eating primates having larger relative brain sizes than leaf-eating primates, due to the more challenging cognitive demands required to find and process fruits (Clutton-Brock &amp; Harvey 1980). An alternative hypothesis argues that larger brain size is necessary for navigating the complexities of primate social life, with larger brains occurring in species who live in bigger, more complex groups relative to those living in pairs or solitarily (Dunbar 1998). There seems to be support for both hypotheses, as large brains are a benefit under both sets of selective pressures.<\/p>\n<p class=\"import-Normal\">Animals with large brains usually have extended life history patterns, and primates are no exception. <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1148\">Life history<\/a> <\/strong>refers to the pace at which an organism grows, reproduces, and ages. Some animals grow very quickly and reproduce many offspring in a short time frame but do not live very long. Other animals grow slowly, reproduce few offspring, reproduce infrequently, and live a long time. Primates are all in the \u201cslow lane\u201d of life history patterns. Compared to animals of similar body size, primates grow and develop more slowly, have fewer offspring per pregnancy, reproduce less often, and live longer. Primates also invest heavily in each offspring. With a few exceptions, most primates only have one offspring at a time. A group of small-bodied monkeys in South America regularly give birth to twins, and some lemurs can give birth to multiple offspring at a time, but these primates are the exception rather than the rule. Primates also reproduce relatively infrequently. The fastest-reproducing primates will produce offspring about every six months, while the slowest, the orangutan, reproduces only once every seven to nine years. This very slow reproductive rate makes the orangutan the slowest-reproducing animal on the planet! Primates are also characterized by having long lifespans. The group that includes humans and large-bodied apes has the most extended life history patterns among all primates, with some large-bodied apes estimated to live up to 58 years in the wild (Robson Et al. 2006).<\/p>\n<figure style=\"width: 392px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image3-5.jpg\" alt=\"Various hands and feet of different primate species.\" width=\"392\" height=\"624\" \/><figcaption class=\"wp-caption-text\">Figure 6.3: These drawings of the hands and feet of different primates show the opposable thumbs and big toes, pentadactyly, flattened nails, and tactile pads characteristic of our Order. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:PrimateFeet.jpg\">PrimateFeet<\/a> by <a href=\"https:\/\/en.wikipedia.org\/wiki\/Richard_Lydekker\">Richard Lydekker<\/a>, original from The Royal Natural History 1:15 (1893), is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\">public domain<\/a>.<\/figcaption><\/figure>\n<p>Primates also differ from other animals in our hands and feet. The Order Primates is a largely <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1150\">arboreal<\/a><\/strong> taxonomic group, meaning that most primates spend a significant amount of their time in trees. As a result, the hands and feet of primates have evolved to move in a three-dimensional environment. Primates have the generalized trait of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1152\">pentadactyly<\/a><\/strong>\u2014 possessing five digits (fingers and toes) on each limb. Many nonprimates, like dogs and horses, have fewer digits because they are specialized for high-speed, <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1154\">terrestrial<\/a><\/strong> (on the ground) running. Pentadactyly is also an ancestral trait, one that dates back to the earliest four-footed animals. Primates today have opposable thumbs and, with the exception of humans, opposable big toes (Figure 6.3). Opposable thumbs and toes are a derived trait that appeared in the earliest primate fossils about 55 million years ago. Having thumbs and big toes that go in a different direction from the rest of the fingers and toes allow primates to be excellent climbers in trees as well as to manipulate objects. Our ability to manipulate objects is further enhanced by the flattened nails on the backs of our fingers and toes that we possess in the place of the claws and hooves that many other mammals have. On the other side of our digits, we have sensitive <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1156\">tactile pads<\/a> <\/strong>that allow us to have a fine sense of touch. Primates use this fine sense of touch for handling food and, in many species, grooming themselves and others. In primates, grooming is an important social currency, through which individuals forge and maintain social bonds.<\/p>\n<table class=\"alignright\" style=\"width: 219.75pt;height: 407px\">\n<caption>Figure 6.4: Primate Traits at a Glance: This table summarizes the suite of traits that differentiate primates from other mammals. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\">Primate at a glance table (Figure 5.3)<\/a> by Stephanie Etting original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/caption>\n<thead>\n<tr style=\"height: 30px\">\n<td class=\"a-C\" style=\"background-color: transparent;padding: 5pt;border: 1pt solid #000000;height: 30px;width: 361.667px\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Primate suite of traits<\/strong><\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"a-R\" style=\"height: 362px\">\n<td class=\"a-C\" style=\"background-color: transparent;padding: 5pt;border: 1pt solid #000000;height: 362px;width: 361.667px\">\n<p class=\"import-Normal\" style=\"text-align: center\">Convergent eyes<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Postorbital bar<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Many have trichromatic colour vision<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Short snouts<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Opposable thumbs and big toes<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Pentadactyly<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Flattened nails<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Tactile pads<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Highly arboreal<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Large brains<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Extended life histories<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Live in the tropics<\/p>\n<\/td>\n<\/tr>\n<tr style=\"height: 15px\">\n<td style=\"height: 15px;width: 362.033px\"><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>Lastly, primates are very social animals. All primates, even those that search for food alone, establish strong social networks within species. Unlike many animals, primates do not migrate: they stay in a relatively stable area for their whole life, often interacting with the same individuals for their long lives. The long-term relationships that primates form with others of their species lead to complex and fascinating social behaviours (see Chapter 7). Finally, nonhuman primates show a clear preference for tropical regions of the world. Most primates are found between the Tropic of Cancer and the Tropic of Capricorn, with only a few taxa living outside these regions. Figure 6.4 shows a summary of primate traits.<\/p>\n<h2 class=\"import-Normal\">Key Traits Used to Distinguish Between Primate Taxa<\/h2>\n<p class=\"import-Normal\">When placing primate species into specific taxonomic groups, we focus on dental characteristics, behavioural adaptations, and locomotor adaptations. Differences in these characteristics across groups reflect constraints of evolutionary history as well as variation in adaptations.<\/p>\n<h3 class=\"import-Normal\"><strong>Dental Characteristics<\/strong><\/h3>\n<p class=\"import-Normal\">Teeth may not seem like the most exciting topic with which to start, but we can learn a tremendous amount about an organism from its teeth. First, teeth are vital to survival. Wild animals do not have the benefit of knives and forks; they rely on their teeth to process their food. Because of this, teeth of any species have evolved to reflect what that organism eats and therefore have a lot to tell us about their diet. Second, variation in tooth size, shape, and number reveals an organism\u2019s evolutionary history. Some taxa have more teeth than others or different forms of teeth. Furthermore, differences in teeth between males and females can tell us about competition over mates (see Chapter 7). Lastly, teeth are overly represented in the fossil record. Enamel is hard, and there is little meat on jaws so carnivores and scavengers often leave them behind. Sometimes, the only remains we have from an extinct taxon is its teeth!<\/p>\n<figure style=\"width: 356px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image4-4-1.jpg\" alt=\"Yawning baboon with large teeth.\" width=\"356\" height=\"266\" \/><figcaption class=\"wp-caption-text\">Figure 6.5: This picture of an open-mouthed Hamadryas baboon demonstrates the diastema between his upper canine and front teeth. This space is taken up by his lower canine when he closes his mouth. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Ha,ha,ha_...._(14986571843).jpg\">Ha,ha,ha .... (14986571843)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/104249543@N07\">Rolf Dietrich Brecher<\/a> from Germany is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\">CC BY-SA 2.0 License<\/a>.<\/figcaption><\/figure>\n<p>Like other mammals, primates are <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1158\">heterodont<\/a><\/strong>: they have multiple types of teeth that are used for different purposes. We have <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1160\">incisors<\/a> <\/strong>for slicing; <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1162\">premolars<\/a> <\/strong>and <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1164\">molars<\/a> <\/strong>for grinding up our food; and <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1166\">canines<\/a><\/strong>, which most primates (not humans) use as weapons against predators and each other. The sizes of canines vary across species and can often be <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1168\">sexually dimorphic<\/a><\/strong>, with males tending to have larger canines than females. Some nonhuman primates <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1170\">hone<\/a><\/strong>, or sharpen, their canines by gnashing the teeth together to sharpen the sides. The upper canine sharpens on the first lower premolar and the lower canine sharpens on the front of the upper canine. As canines get larger, they require a space to fit in order for the jaws to close. This space between the teeth is called a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1172\">diastema<\/a><\/strong> (Figure 6.5).<\/p>\n<p class=\"import-Normal\">We use a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1174\">dental formula<\/a><\/strong> to specify how many incisors, canines, premolars, and molars are in each quadrant of the mouth (half of the top or bottom). For example, Figure 6.6 shows half of the lower teeth of a human. You can see that in half of the mandible, there are two incisors, one canine, two premolars, and three molars. This dental formula is written as 2:1:2:3. (The first number represents the number of incisors, followed by the number of canines, premolars, and molars.)<\/p>\n<figure style=\"width: 241px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image5-5.png\" alt=\"Human mandible with four types of teeth.\" width=\"241\" height=\"424\" \/><figcaption class=\"wp-caption-text\">Figure 6.6:\u00a0 This drawing shows half of the human mandible. With the four types of teeth labeled, you can determine that the dental formula is 2:1:2:3. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Gray997.png\">Gray997<\/a> by <a href=\"https:\/\/en.wikipedia.org\/wiki\/Henry_Vandyke_Carter\">Henry Vandyke Carter<\/a>, original in Henry Gray (1918) Anatomy of the Human Body, Plate 997, is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\">public domain<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">To determine the dental formula, you need to be able to identify the different types of teeth. You can recognize incisors because they often look like spatulas with a flat, blade-like surface. Premolars and molars can be differentiated by the number of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1176\">cusps<\/a><\/strong> that they have. Cusps are the bumps that you can feel with your tongue on the surface of your back teeth. Premolars are smaller than molars and, in primates, often have one or two cusps on them. Molars are bigger, providing a larger chewing surface, and have more cusps. Depending on the species and whether you\u2019re looking at upper or lower teeth, primate molars can have between three and five cusps. Molar cusps can also vary between taxa in how they are arranged; you will learn more about this later in this chapter. Canines are often easy to distinguish because, in most taxa, they are much longer and more conical than the other teeth.<\/p>\n<p class=\"import-Normal\">Teeth also directly reflect an organism\u2019s diet. Primates are known to eat a wide range of plant parts, insects, gums, and, rarely, meat. While all primates eat a variety of foods, what differs among primates are the proportions of each of these food items in the diet. That is, two primates living in the same forest may be eating the same foods but in vastly different proportions, and so we would categorize them as different dietary types. The most common dietary types among primates are those whose diets consist primarily of fruit (<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_954\">frugivores<\/a><\/strong>), those who eat mostly insects (<strong>insectivores<\/strong>), and those who eat primarily leaves (<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_956\">folivores<\/a><\/strong>). A few primate taxa are <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1178\">gummivores<\/a><\/strong>, specializing in eating gums and saps, but we will only focus on the adaptations found in the three primary dietary groups.<\/p>\n<h4 class=\"import-Normal\"><em>Frugivores<\/em><\/h4>\n<p class=\"import-Normal\">Plants want animals to eat their fruits because, in doing so, animals eat the seeds of the fruit and then disperse them far away from the parent plant. Therefore, plants often \u201cadvertise\u201d fruits by making them colourful and easy to spot, full of easy-to-digest sugars that make them taste good and, often, easy to chew and digest (not being too fibrous or tough). For these reasons, frugivores often do not need a lot of specialized traits to consume a diet rich in fruits (Figure 6.7). Their molars usually have a broad chewing surface with low, rounded cusps (referred to as <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1180\">bunodont<\/a> <\/strong>molars). Frugivores have large incisors for slicing through the outer coatings on fruit, and they tend to have stomachs, colons, and small intestines that are intermediate in terms of size and complexity between insectivores and folivores (Chivers &amp; Hladik 1980). They are also usually of intermediate body size between the other two dietary types. Because fruit does not contain protein, frugivores must supplement their diet with protein from insects, leaves, and\/or seeds. Frugivores who get protein by eating seeds evolved to have thicker enamel on their teeth to protect them from excessive wear.<\/p>\n<figure style=\"width: 503px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image6-2.jpg\" alt=\"Upper teeth and maxilla of a frugivore monkey.\" width=\"503\" height=\"331\" \/><figcaption class=\"wp-caption-text\">Figure 6.7: Frugivores are characterized by large incisors, bunodont molars, and digestive tracts that are intermediate in complexity between the other two dietary types. Credit: <a href=\"https:\/\/animaldiversity.org\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Papio_papio\/utr0087\/\">Papio papio (Guinea baboon).jpg<\/a> by Phil Myers on <a href=\"https:\/\/animaldiversity.org\">Animal Diversity Web<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\">CC BY-NC-SA 3.0 License. <\/a><\/figcaption><\/figure>\n<h4 class=\"import-Normal\"><em>Insectivores<\/em><\/h4>\n<p class=\"import-Normal\">While insects can be difficult to find and catch, they are easy to chew and digest. As a result, insectivorous primates usually have small molars with pointed cusps to puncture the exoskeleton of the insects (Figure 6.8), and they have simple stomachs and colons with a long small intestine to process the insects. Nutritionally, insects provide a lot of protein and fat but are not plentiful enough in the environment to support large-bodied animals, so insectivores are usually the smallest of the primates.<\/p>\n<figure style=\"width: 351px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image7-3.jpg\" alt=\"Mandible, upper teeth, and maxilla of insectivore tarsier.\" width=\"351\" height=\"280\" \/><figcaption class=\"wp-caption-text\">Figure 6.8: Insectivores need sharp, pointed molar cusps to break through the exoskeletons of insects. Insects are easy to digest, so these primates have simple digestive tracts. Credit: Tarsier (an insectivor)\u2019s teeth original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Stephanie Etting is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\">CC BY-NC-SA 3.0 License.<\/a> [Includes <a href=\"https:\/\/animaldiversity.org\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Tarsius_syrichta\/lower_lateral1942\/\">Lower_lateral1942<\/a> by Phil Myers on <a href=\"https:\/\/animaldiversity.org\">Animal Diversity Web<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\">CC BY-NC-SA 3.0<\/a>; <a href=\"https:\/\/animaldiversity.org\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Tarsius_syrichta\/ventral\/\">Ventral<\/a> by Phil Myers on <a href=\"https:\/\/animaldiversity.org\">Animal Diversity Web<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\">CC BY-NC-SA 3.0<\/a>.]<\/figcaption><\/figure>\n<h4 class=\"import-Normal\"><em>Folivores<\/em><\/h4>\n<p class=\"import-Normal\">Plants rely on leaves to get energy from the sun, so plants do not want animals to eat their leaves (unlike their fruit). As a result, plants evolved to try to discourage animals from eating their leaves. Leaves often carry toxins, taste bitter, are very fibrous and difficult to chew, and are made of large cellulose molecules that are difficult to break down into usable sugars. Thus, animals who eat leaves need a lot of specialized traits (Figure 6.9). Folivorous primates have broad molars with high, sharp cusps connected by <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1182\">shearing crests<\/a><\/strong>. These molar traits allow folivores to physically break down fibrous leaves when chewing. Folivores then chemically break down cellulose molecules into usable energy. To do this, some folivores have complex stomachs with multiple compartments, while others have large, long intestines and special gut bacteria that can break up cellulose. Folivores are usually the largest bodied of all primates, and they tend to spend a large portion of their day digesting their food, so they are less active than frugivores or insectivores.<\/p>\n<figure style=\"width: 468px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image8-2.jpg\" alt=\"Upper teeth and maxilla of a monkey shows folivore traits.\" width=\"468\" height=\"337\" \/><figcaption class=\"wp-caption-text\">Figure 6.9: To derive energy from leaves, folivores, like this Trachypithecus (dusky leaf monkey), have smaller incisors and high sharp molar cusps connected by shearing crests. Credit: <a href=\"https:\/\/animaldiversity.org\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Trachypithecus_obscurus\/utr0075\/\">Trachypithecus obscurus (dusky leaf monkey) upper teeth<\/a> by Phil Myers on <a href=\"https:\/\/animaldiversity.org\">Animal Diversity Web<\/a> has been modified (background removed, labels added by Stephanie Etting) is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\">CC BY-NC-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<h3 class=\"import-Normal\"><strong>Behavioural Adaptations<\/strong><\/h3>\n<p class=\"import-Normal\">Since Chapter 6 is dedicated to primate behaviour, we will only briefly discuss variations in activity patterns, social grouping, and habitat use. Primate groups differ in <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1184\">activity patterns<\/a><\/strong>: whether they are active during the day (<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1012\">diurnal<\/a><\/strong>), at night (<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1010\">nocturnal<\/a><\/strong>), or through the 24-hour period (<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1186\">cathemeral<\/a><\/strong>). Primate taxa vary in social groupings: some are primarily solitary, others live in pairs, and still others live in groups of varying sizes and compositions. Lastly, some taxa are primarily arboreal while others are more terrestrial.<\/p>\n<h3 class=\"import-Normal\"><strong>Locomotor Adaptations<\/strong><\/h3>\n<p class=\"import-Normal\">Finally, primate groups vary in their adaptations for different forms of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1188\">locomotion<\/a><\/strong>, or how they move around. Living primates are known to move by vertical clinging and leaping, quadrupedalism, brachiation, and bipedalism.<\/p>\n<p class=\"import-Normal\"><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1190\">Vertical clinging and leaping<\/a> <\/strong>is when an animal grasps a vertical branch with its body upright, pushes off with long hind legs, and then lands on another vertical support branch (Figure 6.10a). Animals who move in this way usually have longer legs than arms, long fingers and toes, and smaller bodies. Vertical clinger leapers also tend to have elongated ankle bones, which serve as a lever to help them push off with their legs and leap to another branch (Figure 6.10b).<\/p>\n<p>&lt;!-- marker for original place of <\/p><\/div>\n<\/p><\/div>\n<p> --&gt;<\/p>\n<figure id=\"attachment_181-11\" aria-describedby=\"caption-attachment-181-11\" style=\"width: 608px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-147\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/5.10.jpg\" alt=\"Movement of vertical clinger and leaper, and tarsier skeleton.\" width=\"608\" height=\"462\" \/><figcaption id=\"caption-attachment-181-11\" class=\"wp-caption-text\">Figure 6.10a: Vertical clingers and leapers have longer legs than arms, long lower backs, and long fingers and toes. They also have elongated ankle bones to help them push off when leaping. Credit: a. <a href=\"https:\/\/upload.wikimedia.org\/wikipedia\/commons\/6\/6e\/Propithecus_vertical_clinging_and_leaping.svg\">Propithecus vertical clinging and leaping<\/a> by Terpsichores is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/\"> CC BY-SA 3.0 License<\/a>. 6.10b: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Em_-_Tarsius_tarsier_-_3.jpg\">Tarsier skeleton<\/a> by Em\u0151ke D\u00e9nes has been modified (background removed) by Stephanie Etting and is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/\">CC BY-SA 4.0 License<\/a>. Original Spectral tarsier (Tarsius tarsier) skeleton at the Cambridge University Museum of Zoology, England.)<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<div class=\"learning-objectives\">\n<p class=\"import-Normal\"><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1192\">Quadrupedalism<\/a><\/strong>, walking on all fours, is the most common form of locomotion among primates. Quadrupedal animals usually have legs and arms that are about the same length and a tail for balance. Arboreal quadrupeds (Figure 6.11a) usually have shorter arms and legs and longer tails, while terrestrial quadrupeds (Figure 6.11b) have longer arms and legs and, often, shorter tails. These differences relate to the lower centre of gravity needed by arboreal quadrupeds for balance in trees and the longer tail required for better balance when moving along the tops of branches. Terrestrial quadrupeds have longer limbs to help them cover more distance more efficiently.<\/p>\n<\/div>\n<figure id=\"attachment_181-12\" aria-describedby=\"caption-attachment-181-12\" style=\"width: 704px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-148\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/5.11.jpg\" alt=\"Arboreal quadrupedal monkey and terrestrial quadrupedal monkey.\" width=\"704\" height=\"251\" \/><figcaption id=\"caption-attachment-181-12\" class=\"wp-caption-text\">Figure 6.11a\/b: Two examples of quadrupedal primates. The capuchin monkey skeleton on the left (a) is a typical arboreal quadruped with shorter arms and legs, longer fingers and toes, and a long tail. The baboon skeleton on the right (b) is a terrestrial quadruped with relatively long arms and legs, shorter fingers and toes, and a short tail. Credits: 6.11a. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Description_iconographique_compar%C3%A9e_du_squelette_et_du_syst%C3%A8me_dentaire_des_mammif%C3%A8res_r%C3%A9cents_et_fossiles_(Sapajus_apella).jpg\">Capuchin monkey skeleton<\/a> by Henri-Marie Ducrotay de Blainville is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\">public domain<\/a>. 6.11b. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Description_iconographique_compar%C3%A9e_du_squelette_et_du_syst%C3%A8me_dentaire_des_mammif%C3%A8res_r%C3%A9cents_et_fossiles_(Papio_ursinus).jpg\">Baboon<\/a> by Henri-Marie Ducrotay de Blainville is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\">public domain<\/a>.<\/figcaption><\/figure>\n<div class=\"learning-objectives\">\n<p class=\"import-Normal\">The third form of locomotion seen in primates is<strong> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1194\">brachiation<\/a><\/strong>, the way of moving you used if you played on \u201cmonkey bars\u201d as a child. Brachiation involves swinging below branches by the hands (Figure 6.12a). To be an efficient brachiator, a primate needs to have longer arms than legs, flexible shoulders and wrists, a short lower back, and no tail (Figure 6.12b). Some primates move via <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1196\">semi-brachiation<\/a><\/strong>, in which they swing below branches but do not have all of the same specializations as brachiators. Semi-brachiators have flexible shoulders, but their arms and legs are about the same length, which is useful because they are quadrupedal when on the ground. They also use long <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1198\">prehensile tails<\/a><\/strong> as a third limb when swinging (Figure 6.13). The underside of the tail has a tactile pad, resembling your fingerprints, for better grip.<\/p>\n<\/div>\n<figure id=\"attachment_181-13\" aria-describedby=\"caption-attachment-181-13\" style=\"width: 1600px\" class=\"wp-caption alignnone\"><img class=\"wp-image-149 size-full\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/5.12.jpg\" alt=\"Primate swinging through branches and gibbon skeleton.\" width=\"1600\" height=\"800\" \/><figcaption id=\"caption-attachment-181-13\" class=\"wp-caption-text\">Figure 6.12a. Example of brachiation. 6.12b. Skeleton of a typical brachiator, showing longer arms than legs, short back, and lack of a tail. Credit: a. <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\">Brachiator (Figure 5.9b)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>. b. <a href=\"https:\/\/upload.wikimedia.org\/wikipedia\/commons\/a\/a3\/Giboia.jpg\">Skeleton of Gibbon (Giboia) <\/a>by Joxerra Aihartza is under a <a href=\"https:\/\/artlibre.org\">Free Art License<\/a>.<\/figcaption><\/figure>\n<div class=\"learning-objectives\">\n<figure style=\"width: 565px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image15-1.jpg\" alt=\"Spider monkey swinging below a rope.\" width=\"565\" height=\"377\" \/><figcaption class=\"wp-caption-text\">Figure 6.13. Spider monkeys are considered semi-brachiators, as they can swing below branches but use their tails as a third limb. On the ground they move via quadrupedal locomotion. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Ateles-fusciceps_54724770b.jpg\">Ateles-fusciceps 54724770b<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:LeaMaimone\">LeaMaimone<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.5\/legalcode\">CC BY 2.5 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Lastly, humans move around on two feet, called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1200\">bipedalism<\/a><\/strong>. Some nonhuman primates will occasionally travel on two feet but do so awkwardly and never for long distances. Among mammals, only humans have evolved to walk with a striding gait on two legs as a primary form of locomotion.<\/p>\n<h2 class=\"import-Normal\">Primate Diversity<\/h2>\n<p class=\"import-Normal\">As we begin exploring the different taxa of primates, it is important to keep in mind the hierarchical nature of taxonomic classification and how this relates to the key characteristics that will be covered. Figure 6.14 summarizes the major taxonomic groups of primates that you will learn about here. If you locate humans on the chart, you can trace our classification and see all of the categories getting more inclusive as you work your way up to the Order Primates. This means that humans will have the key traits of each of those groups. It is a good idea to refer to the figure to orient yourself as we discuss each taxon.<\/p>\n<figure style=\"width: 2048px\" class=\"wp-caption alignnone\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image16-1.jpg\" alt=\"Taxonomic chart shows primate order, suborder, infraorder, superfamily, and species.\" width=\"2048\" height=\"1154\" \/><figcaption class=\"wp-caption-text\">Figure 6.14: This taxonomy chart shows the major groups of primate taxa, starting with the largest category (Order) and moving to more specific categories and examples. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\">A full text description of this image is available<\/a>. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\">Primate taxonomy char (Figure 5.11)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/\">CC BY-NC 4.0 License<\/a>. [Includes <a href=\"https:\/\/phylopic.org\/image\/d6cfb28f-136e-4a20-a5ac-8eb353c7fc4a\/\">Lemur catta Linnaeus, 1759<\/a> by Roberto D\u00edaz Sibaja, <a href=\"https:\/\/creativecommons.org\/licenses\/by\/3.0\/\">CC BY 3.0<\/a>; <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\">Lorisoidea<\/a> original to<a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\"> Explorations: An Open Invitation to Biological Anthropology<\/a> by Katie Nelson, <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0<\/a>; <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\">Tarsiiformes<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson, <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0<\/a>; <a href=\"https:\/\/phylopic.org\/image\/156b515d-f25c-4497-b15b-5afb832cc70c\/\">Cebinae Bonaparte, 1831<\/a> by Sarah Werning, <a href=\"https:\/\/creativecommons.org\/licenses\/by\/3.0\/\">CC BY 3.0<\/a>; <a href=\"https:\/\/phylopic.org\/image\/899742c2-9a40-4fa0-b2cd-2eb133c8f6e8\/\">Colobus guereza Ruppell, 1835<\/a> by Yan Wong, designated to the <a href=\"https:\/\/creativecommons.org\/publicdomain\/zero\/1.0\/\">public domain (CC0)<\/a>; <a href=\"https:\/\/phylopic.org\/image\/72f2f854-f3cd-4666-887c-35d5c256ab0f\/\">Papio cynocephalus<\/a> by Owen Jones, designated to the <a href=\"https:\/\/creativecommons.org\/publicdomain\/zero\/1.0\/\">public domain (CC0)<\/a>; <a href=\"https:\/\/pixabay.com\/vectors\/animals-silhouette-wolf-elephant-2755766\/\">animals silhouette wolf elephant (2755766)<\/a> by <a href=\"https:\/\/pixabay.com\/users\/mohamed_hassan-5229782\/\">mohamed_hassan<\/a>, <a href=\"https:\/\/pixabay.com\/service\/terms\/#license\">Pixabay License<\/a>.]<\/figcaption><\/figure>\n<h3 class=\"import-Normal\"><strong>Suborder Strepsirrhini<\/strong><\/h3>\n<figure style=\"width: 387px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image17-1.jpg\" alt=\"Eight strepsirrhine species.\" width=\"387\" height=\"605\" \/><figcaption class=\"wp-caption-text\">Figure 6.15: (Clockwise from top right) sifaka, black-and-white ruffed lemur, loris, galago, slender loris, mouse lemur, aye-aye, and ring-tailed lemur. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Extant_Strepsirrhini.jpg\">Extant Strepsirrhini<\/a> a collective work by <a href=\"https:\/\/www.flickr.com\/people\/23661161@N02\">Mark Dumont<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\">CC BY-SA 3.0 License<\/a>. [Includes <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Katta_csal%C3%A1d.jpg\">Katta csal\u00e1d<\/a> by Veszpr\u00e9mi \u00c1llatkert, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\">CC BY-SA 3.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Aye-aye_at_night_in_the_wild_in_Madagascar.jpg\">Aye-aye at night in the wild in Madagascar<\/a> by Frank Vassen, <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/deed.en\">CC BY 2.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Diademed_ready_to_push_off.jpg\">Diademed ready to push off<\/a> by Michael Hogan, designated to the <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/cc0\/\">public domain (CC0)<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Juvenile_Black-and-White_Ruffed_Lemur,_Mantadia,_Madagascar.jpg\">Juvenile Black-and-White Ruffed Lemur, Mantadia, Madagascar<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/42244964@N03\">Frank Vassen<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/legalcode\">CC BY 2.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Microcebus_murinus_-Artis_Zoo,_Amsterdam,_Netherlands-8a.jpg\">Microcebus murinus -Artis Zoo, Amsterdam, Netherlands-8a<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/46956042@N00\">Arjan Haverkamp<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/legalcode\">CC BY 2.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Slow_Loris.jpg\">Slow Loris<\/a> by Jmiksanek, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\">CC BY-SA 3.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Slender_Loris.jpg\">Slender Loris<\/a> by Kalyan Varma (<a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Kalyanvarma\">Kalyanvarma<\/a>), <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\">CC BY-SA 4.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Garnett&apos;s_Galago_(Greater_Bushbaby).jpg\">Garnett's Galago (Greater Bushbaby)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/23661161@N02\">Mark Dumont<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/legalcode\">CC BY 2.0<\/a>.]<\/figcaption><\/figure>\n<p>The Order Primates is subdivided into Suborder Strepsirrhini and Suborder Haplorrhini, which, according to molecular estimates, split about 70\u201380 million years ago (Pozzi et al. 2014). The strepsirrhines include the groups commonly called lemurs, lorises, and galagos (Figure 6.15). Strepsirrhines differ from haplorrhines in many ways, most of which involve retaining ancestral traits from the earliest primates. Strepsirrhines do have two key derived traits that evolved after they diverged from the haplorrhines: the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1202\">grooming claw<\/a> <\/strong>(Figure 6.16) on the second digit of each foot, and the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1204\">tooth comb<\/a><\/strong> (or <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1206\">dental comb<\/a><\/strong>) located on the lower, front teeth (Figure 6.17). In most strepsirrhines, there are six teeth in the toothcomb\u2014four incisors and two canines. Other than the tooth comb, the teeth of strepsirrhines are fairly simple and are neither large or distinctive relative to haplorrhines.<\/p>\n<figure style=\"width: 237px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image18.jpg\" alt=\"A long, thin dark claw is visible in contrast to flat dark nails on the other digits.\" width=\"237\" height=\"202\" \/><figcaption class=\"wp-caption-text\">Figure 6.16: The foot of a ring-tailed lemur showing its grooming claw on the second digit. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Lemur_catta_toilet_claw.jpg\">Lemur catta toilet claw<\/a> by Alex Dunkel (Maky) is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/3.0\/legalcode\">CC BY 3.0 License.<\/a><\/figcaption><\/figure>\n<p class=\"import-Normal\">Compared to haplorrhines, strepsirrhines rely more on nonvisual senses. Strepsirrhines get their name because they have wet noses (<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1208\">rhinariums<\/a><\/strong>) like cats and dogs, a trait that, along with a longer snout, reflect strepsirrhines\u2019 greater reliance on olfaction relative to haplorrhines. Many strepsirrhines use <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1210\">scent marking<\/a><\/strong>, including rubbing scent glands or urine on objects in the environment to communicate with others. Additionally, many strepsirrhines have mobile ears that they use to locate insect prey and predators. While strepsirrhines have a better sense of smell than haplorrhines, their visual adaptations are more ancestral. Strepsirrhines have less convergent eyes than haplorrhines and therefore all have postorbital bars, whereas haplorrhines have full postorbital closure (see Figure 6.2). All strepsirrhines have a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1212\">tapetum lucidum<\/a><\/strong>, a reflective layer at the back of the eye that reflects light and thereby enhances the ability to see in low-light conditions. It is the same layer that causes your dog or cat to have \u201cyellow eye\u201d when you take photos of them with the flash on. This is a trait thought to be ancestral among mammals as a whole.<\/p>\n<figure style=\"width: 292px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image19-1.jpg\" alt=\"The lower, front teeth are long, thin, tightly together in a line, and project towards the lips.\" width=\"292\" height=\"354\" \/><figcaption class=\"wp-caption-text\">Figure 6.17: The lower front teeth of a ring-tailed lemur showing the six teeth of the tooth comb: four incisors and two canines. The teeth that superficially look like canines are premolars. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Lemur_catta_toothcomb.jpg\">Lemur catta toothcomb<\/a> by Alex Dunkel (Maky) is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/3.0\/legalcode\">CC BY 3.0 license.<\/a><\/figcaption><\/figure>\n<p class=\"import-Normal\">Strepsirrhines also differ from haplorrhines in some aspects of their ecology and behaviour. The majority of strepsirrhines are solitary, traveling alone to search for food; a few taxa are more social. Most strepsirrhines are also nocturnal and arboreal. Strepsirrhines are, on average, smaller than haplorrhines, and so many of them have a diet consisting of insects and fruit, with few taxa eating primarily leaves. Lastly, most strepsirrhines are good at leaping, with several taxa specialized for vertical clinging and leaping. In fact, among primates, all but one of the vertical clinger leapers belong to the Suborder Strepsirrhini.<\/p>\n<p class=\"import-Normal\">Strepsirrhines can be found all across Asia, Africa, and on the island of Madagascar (Figure 6.18). The Suborder Strepsirrhini is divided into two groups: (1) the lemurs of Madagascar and (2) the lorises, pottos, and galagos of Africa and Asia. By molecular estimates, these two groups split about 65 million years ago (Pozzi Et al. 2014).<\/p>\n<figure style=\"width: 443px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image20-1.png\" alt=\"Map strepsirrhine primates locations.\" width=\"443\" height=\"342\" \/><figcaption class=\"wp-caption-text\">Figure 6.18: Geographic distribution of living strepsirrhines. Lemurs live only on Madagascar, while lorises and galagos live across Central Africa and South and Southeast Asia. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\">Geographic distribution of living strepsirrhines (Figure 5.16)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Elyssa Ebding at <a href=\"https:\/\/www.csuchico.edu\/geop\/geoplace\/index.shtml\">GeoPlace, California State University, Chico<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<h4><em>Lemurs of Madagascar<\/em><\/h4>\n<p class=\"import-Normal\">Madagascar is an island off the east coast of Africa, and it is roughly the size of California, Oregon, and Washington combined. It has been separated from Africa for about 130 million years and from India for about 85 million years, which means it was already an island when strepsirrhines got there approximately 60\u201370 million years ago. Only a few mammal species ever reached Madagascar, and so when lemurs arrived they were able to flourish into a variety of forms.<\/p>\n<p class=\"import-Normal\">The lemurs of Madagascar are much more diverse compared to their mainland counterparts, the lorises and galagos. While many Malagasy strepsirrhines are nocturnal, plenty of others are diurnal or cathemeral. They range in body size from the smallest of all primates, the mouse lemur, some species of which weigh a little over an ounce (see Figure 6.15), up to the largest of all strepsirrhines, the indri, which weighs up to about 20 pounds (Figure 6.19). Lemurs include species that are insectivorous, frugivorous, and folivorous. A couple of members of this group have unusual diets for primates, including the gummivorous fork-marked and bamboo lemurs, who are able to metabolize the cyanide in bamboo. The most unique lemur is the aye-aye (depicted in Figure 6.15). This nocturnal lemur has rodent-like front teeth that grow continuously and a long-bony middle finger that it uses to fish grubs out of wood. It has a very large brain compared to other strepsirrhines, which it fuels with a diet that includes bird\u2019s eggs and other animal matter. Based on genetic estimates and morphological studies, it is believed that aye-ayes were the first lemurs to separate from all other strepsirrhines and to evolve on their own since strepsirrhines arrived in Madagascar (Matsui Et al. 2009).<\/p>\n<figure style=\"width: 326px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image21-1-1.jpg\" alt=\"Two Indis in a tree.\" width=\"326\" height=\"217\" \/><figcaption class=\"wp-caption-text\">Figure 6.19: Indris, the largest of the lemurs. These folivorous lemurs are vertical clingers and leapers and live in pairs. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Indri_indri_0003.jpg\">Indri indri 0003<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Christophe_Germain\">Christophe Germain<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Lemurs are also diverse in terms of social behaviour: Many lemurs are solitary foragers, some live in pairs, others in small groups, still others in larger groups, and some, like the red-ruffed lemur, live in unique and complex social groups (Vasey 2006). Lemurs include some of the best vertical clingers and leapers, and while many lemurs are quadrupedal, even the quadrupedal lemurs are quite adept at leaping. Malagasy strepsirrhines also exhibit a few unusual traits. They are highly seasonal breeders, often mating only during a short window once a year (Wright 1999). Female ring-tailed lemurs, for example, come into estrus one day a year for a mere six hours. Unlike most primates, where males are typically large and dominant, Malagasy strepsirrhines feature socially dominant females that are similar in size to males and have priority access to resources.<\/p>\n<h4 class=\"import-Normal\"><em>Lorises, Pottos, and Galagos of Asia and Africa<\/em><\/h4>\n<figure style=\"width: 207px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image22-1.jpg\" alt=\"Slow loris hanging from a branch.\" width=\"207\" height=\"309\" \/><figcaption class=\"wp-caption-text\">Figure 6.20: This slow loris, like all others in this taxonomic group, is solitary and nocturnal, with a diet heavy in insects and fruit. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Nycticebus_coucang_002.jpg\">Nycticebus coucang 002<\/a> by David Haring \/ Duke Lemur Center is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/deed.en\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p>Unlike the lemurs of Madagascar, lorises, pottos, and galagos live in areas where they share their environments with monkeys and apes, who often eat similar foods. Lorises live across South and Southeast Asia, while pottos and galagos live across Central Africa. Because of competition with larger-bodied monkeys and apes, mainland strepsirrhines are more restricted in the niches they can fill in their environments and so are less diverse than the lemurs.<\/p>\n<p>The strepsirrhines of Africa and Asia are all nocturnal and solitary, with little variation in body size and diet. For the most part, the diet of lorises, pottos, and galagos consists of fruits and insects. A couple of species eat more gum, but overall the diet of this group is narrow when compared to the Malagasy lemurs. Lorises (Figure 6.20) and pottos are known for being slow, quadrupedal climbers, moving quietly through the forests to avoid being detected by predators. These strepsirrhines have developed additional defences against predators. Lorises, for example, eat a lot of caterpillars, which makes their saliva slightly toxic. Loris mothers bathe their young in this toxic saliva, making the babies unappealing to predators. In comparison to the slow-moving lorises and pottos, galagos are active quadrupedal runners and leapers that scurry about the forests at night. Galagos make distinctive calls that sound like a baby crying, which has led to their nickname \u201cbushbabies.\u201d Figure 6.21 summarizes the key differences between these two groups of strepsirrhines.<\/p>\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<caption>Figure 6.21: Strepsirrhini at a glance: This table summarizes the key differences between the two groups of strepsirrhines. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\">Strepsirrhines at a glance table (Figure 5.19)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\">CC BY-NC-SA 4.0 License<\/a>. [Includes <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Ringtailed_Lemurs_in_Berenty.jpg\">Ringtailed Lemurs in Berenty<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/50852241@N00\">David Dennis<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\">CC BY-SA 2.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Komba_u%C5%A1at%C3%A1.jpg\">Komba u\u0161at\u00e1<\/a> by Petr Hamern\u00edk, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\">CC BY-SA 4.0<\/a>.]<\/caption>\n<thead>\n<tr>\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong><img class=\"alignnone\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image23-1.jpg\" alt=\"Baby primate on the back of adult primate.\" width=\"231\" height=\"165\" \/><\/strong><\/p>\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Lemurs<\/strong><\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong><img class=\"alignnone\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image24-1.jpg\" alt=\"Small primate with big eyes and long tail.\" width=\"198\" height=\"132\" \/><\/strong><\/p>\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Lorises, Pottos, and Galagos<\/strong><\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"a0-R\">\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Geographic range<\/strong><\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Madagascar<\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">South and Southeast Asia<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Central Africa<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a0-R\">\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Activity patterns<\/strong><\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Diurnal, nocturnal, or cathemeral<\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Nocturnal<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a0-R\">\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Dietary types<\/strong><\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Insectivore, frugivore, or folivore<\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Insectivore, frugivore<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a0-R\">\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Social groupings<\/strong><\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Solitary, pairs, or small to large groups<\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Solitary<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a0-R\">\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Forms of locomotion<\/strong><\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Vertical clinger leapers, quadrupedal<\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Slow quadrupedal climbers and active quadrupedal runners<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h3 class=\"import-Normal\"><strong>Suborder Haplorrhini<\/strong><\/h3>\n<p class=\"import-Normal\">When the two primate suborders split from one another, strepsirrhines retained more ancestral traits while haplorrhines developed more derived traits, which are discussed below.<\/p>\n<p class=\"import-Normal\">As mentioned earlier, haplorrhines have better vision than strepsirrhines. This is demonstrated by the full postorbital closure protecting the more convergent eyes that haplorrhines possess (with one exception seen in Figure 6.2). Most haplorrhines are trichromatic, and all have a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1410\">fovea<\/a><\/strong>, a depression in the retina at the back of the eye containing concentrations of cells that allows them to see things very close up in great detail. The heavier reliance on vision over olfaction is also reflected in the shorter snouts ending with the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1412\">dry nose<\/a> <\/strong>(no rhinarium) of haplorrhines. All but two genera of living haplorrhines are active during the day, so this group lacks the tapetum lucidum that is so useful to nocturnal species. On average, haplorrhines also have larger brains relative to their body size when compared with strepsirrhines.<\/p>\n<p class=\"import-Normal\">The Haplorrhini differ from the Strepsirrhini in their ecology and behaviour as well. Haplorrhines are generally larger than strepsirrhines, and they tend to be folivorous and frugivorous. This dietary difference is reflected in the teeth of haplorrhines, which are broader with more surface area for chewing. The larger body size of this taxon also influences locomotion. Only one haplorrhine is a vertical clinger and leaper. Most members of this suborder are quadrupedal, with one subgroup specialized for brachiation. A few haplorrhine taxa are <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1414\">monomorphic<\/a><\/strong>, meaning males and females are the same size, but many members of this group show moderate to high sexual dimorphism in body size and canine size. Haplorrhines also differ in social behaviour. All but two haplorrhines live in groups, which is very different from the primarily solitary strepsirrhines. Differences between the two suborders are summarized in Figure 6.22.<\/p>\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<caption>Figure 6.22: Suborders at a glance: This table summarizes the key differences between the two primate suborders. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\">Suborders at a glance table (Figure 5.20)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\">CC BY-NC-SA 4.0 License<\/a>. [Includes <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Black-and-White_Ruffed_Lemur,_Mantadia,_Madagascar.jpg\">Black-and-White Ruffed Lemur, Mantadia, Madagascar<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/42244964@N03\">Frank Vassen<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/legalcode\">CC BY 2.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Crab_eating_macaque_face.jpg\">Crab eating macaque face<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Bruce89\">Bruce89<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\">CC BY-SA 4.0<\/a>.]<\/caption>\n<thead>\n<tr>\n<td class=\"a1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong><img class=\"alignnone\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image25.jpg\" alt=\"Black-and-white ruffed lemur.\" width=\"213\" height=\"159\" \/><\/strong><strong>Suborder Strepsirrhini<\/strong><\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong><img class=\"alignnone\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image26-1.jpg\" alt=\"Crab-eating macaque.\" width=\"137\" height=\"137\" \/><\/strong><\/p>\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Suborder Haplorrhini<\/strong><\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"a1-R\">\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Sensory adaptations<\/strong><\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Rhinarium<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Longer snout<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Eyes less convergent<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Postorbital bar<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Tapetum lucidum<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Mobile ears<\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">No rhinarium<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Short snout<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Eyes more convergent<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Postorbital plate<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">No tapetum lucidum<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Many are trichromatic<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Fovea<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a1-R\">\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Dietary differences<\/strong><\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Mostly insectivores and frugivores, few folivores<\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Few insectivores, mostly frugivores and folivores<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a1-R\">\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Activity patterns and Ecology<\/strong><\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Mostly nocturnal, few diurnal or cathemeral<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Almost entirely arboreal<\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Only two are nocturnal, rest are diurnal<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Many arboreal taxa, also many terrestrial taxa<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a1-R\">\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Social groupings<\/strong><\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Mostly solitary, some pairs, small to large groups<\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Only two are solitary, all others live in pairs, small to very large groups<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a1-R\">\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Sexual dimorphism<\/strong><\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Minimal to none<\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Few taxa have little\/none, many taxa show moderate to high dimorphism<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p class=\"import-Normal\">Suborder Haplorrhini is divided into three infraorders: Tarsiiformes, which includes the tarsiers of Asia; Platyrrhini, which includes the monkeys of Central and South America; and Catarrhini, a group that includes the monkeys of Asia and Africa, apes, and humans. According to molecular estimates, tarsiers split from the other haplorrhines close to 70 million years ago, and platyrrhines split from catarrhines close to 46 million years ago (Pozzi Et al. 2014).<\/p>\n<h4 class=\"import-Normal\"><em>Infraorder Tarsiiformes of Asia<\/em><\/h4>\n<figure style=\"width: 188px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image27-1.jpg\" alt=\"Tarsier gripping a branch.\" width=\"188\" height=\"160\" \/><figcaption class=\"wp-caption-text\">Figure 6.23: Tarsiers are the only living representatives of this Infraorder. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Tarsier_Sanctuary,_Corella,_Bohol_(2052878890).jpg\">Tarsier Sanctuary, Corella, Bohol (2052878890)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/46274125@N00\">yeowatzup<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/legalcode\">CC BY 2.0 License<\/a>.<\/figcaption><\/figure>\n<figure style=\"width: 362px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image28-1.png\" alt=\"Map of Southeast Asia shows distribution of tarsiers.\" width=\"362\" height=\"279\" \/><figcaption class=\"wp-caption-text\">Figure 6.24: Tarsiiformes are found in the tropical forests of multiple islands in Southeast Asia including Sumatra, Borneo, Celebes, and the Philippines. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\">Infraorder Tarsiiformes of Asia map (Figure 5.22)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Elyssa Ebding at <a href=\"https:\/\/www.csuchico.edu\/geop\/geoplace\/index.shtml\">GeoPlace, California State University, Chico<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p>Today, the Infraorder Tarsiiformes includes only one genus, <em>Tarsius <\/em>(Figure 6.23). Tarsiers are small-bodied primates that live in Southeast Asian forests (Figure 6.24) and possess an unusual collection of traits that have led to some debate about their position in the primate taxonomy. They are widely considered members of the haplorrhine group because they share several derived traits with monkeys, apes, and humans, including dry noses, a fovea, not having a tapetum lucidum, and eyes that are more convergent. Tarsiers also have some traits that are more like strepsirrhines and some that are unique. Tarsiers are the only haplorrhine that are specialized vertical clinger leapers, a form of locomotion only otherwise seen in some strepsirrhines. Tarsiers actually get their name because their ankle (tarsal) bones are elongated to provide a lever for vertical clinging and leaping. Tarsiiformes are also small, with most species weighing between 100 and 150 grams. Like strepsirrhines, tarsiers are nocturnal, but because they lack a tapetum lucidum, tarsiers compensate by having enormous eyes. In fact, each eye of a tarsier is larger than its brain. These large eyes allow enough light in for tarsiers to still be able to see well at night without the reflecting layer in their eyes. To protect their large eyes, tarsiers have a partially closed postorbital plate that appears somewhat intermediate between the postorbital bar of strepsirrhines and the full postorbital closure of other haplorrhines (Figure 6.25). Tarsiers have different dental formulas on their upper and lower teeth. On the top, the dental formula is 2:1:3:3, but on the bottom it is 1:1:3:3. Other unusual traits of tarsiers include having two grooming claws on each foot and the ability to rotate their heads around 180 degrees, a trait useful in locating insect prey. The tarsier diet is considered <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1416\">faunivorous<\/a> <\/strong>because it consists entirely of animal matter, making them the only primate not to eat any vegetation. They are only one of two living haplorrhines to be solitary, the other being the orangutan. Most tarsiers are not sexually dimorphic, like strepsirrhines, although males of a few species are slightly larger than females.<\/p>\n<figure style=\"width: 486px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image29-1.jpg\" alt=\"Front view of tarsier skull.\" width=\"486\" height=\"323\" \/><figcaption class=\"wp-caption-text\">Figure 6.25: Skull of a tarsier showing very large eye sockets and partially closed postorbital plates. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Tarsier_skull.jpg\">Tarsier skull<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/65438265@N00\">Andrew Bardwell<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\">CC BY-SA 2.0 License.<\/a><\/figcaption><\/figure>\n<p class=\"import-Normal\">Two alternative classifications have emerged due to the unusual mix of traits that tarsiers have. Historically, tarsiers were grouped with lemurs, lorises, and galagos into a suborder called Prosimii. This classification was based on tarsiers, lemurs, lorises, and galagos all having grooming claws and similar lifestyles. Monkeys, apes, and humans were then separated into a suborder called the Anthropoidea. These suborder groupings were based on <em>grade<\/em> rather than <em>clade<\/em>. Today, most people use Suborders Strepsirrhini and Haplorrhini, which are clade groupings based on the derived traits that tarsiers share with monkeys, apes, and humans. The Strepsirrhini\/Haplorrhini dichotomy is also supported by the genetic evidence that indicates tarsiers are more closely related to monkeys, apes, and humans (Jameson Et al. 2011). Figure 6.26 summarizes the unusual mix of traits seen in tarsiers.<\/p>\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<caption>Figure 6.26: Tarsiers at a glance: Tarsiers have a mix of traits that lead to debate about their classification. While they have some unique characteristics, they also have traits that superficially resemble strepsirrhines, and many derived traits shared with haplorrhines. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\">Tarsiers at a glance table (Figure 5.24)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/caption>\n<thead>\n<tr>\n<td class=\"a2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Like Strepsirrhini<\/strong><\/p>\n<\/td>\n<td class=\"a2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Unique<\/strong><\/p>\n<\/td>\n<td class=\"a2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Like Haplorrhini<\/strong><\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"a2-R\">\n<td class=\"a2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Very small<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Nocturnal<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Highly insectivorous<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Solitary<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Vertical clinger-leapers<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Little\/no sexual dimorphism<\/p>\n<\/td>\n<td class=\"a2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Two grooming claws<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">2:1:3:3\/1:1:3:3 dental formula<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Do not eat vegetation<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Can rotate their heads nearly 180 degrees<\/p>\n<\/td>\n<td class=\"a2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Almost full PO closure<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">More convergent eyes<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">No tapetum lucidum<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">No rhinarium<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Genetic evidence<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Fovea<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h4 class=\"import-Normal\"><em>Infraorder Platyrrhini of Central and South America<\/em><\/h4>\n<figure id=\"attachment_179-3\" aria-describedby=\"caption-attachment-179-3\" style=\"width: 329px\" class=\"wp-caption alignleft\"><img class=\"wp-image-165\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image30-e1686352290168.png\" alt=\"Map of South America shows where platyrrhines live.\" width=\"329\" height=\"324\" \/><figcaption id=\"caption-attachment-179-3\" class=\"wp-caption-text\">Figure 6.27: Geographic distribution of the platyrrhines across the southern part of Central America and the tropical and termporate regions of South America. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\">Infraorder Platyrrhini map<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Elyssa Ebding at <a href=\"https:\/\/www.csuchico.edu\/geop\/geoplace\/index.shtml\">GeoPlace, California State University, Chico<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p>The platyrrhines are the only nonhuman primates in Central and South America (Figure 6.27) and so, like the lemurs of Madagascar, have diversified into a variety of forms in the absence of competition. Infraorder Platyrrhini get their name from their distinctive nose shape. \u201cPlaty\u201d means flat and \u201crhini\u201d refers to noses, and, indeed, platyrrhines have noses that are flat and wide, with nostrils that are far apart, facing outward, and usually round in shape (Figure 6.28). This nose shape is very different from what we see in catarrhines.<\/p>\n<p>On average, platyrrhines are smaller and less sexually dimorphic than catarrhines, and they have retained the more ancestral primate dental formula of 2:1:3:3. Platyrrhines are all highly arboreal, whereas many catarrhines spend significant time on the ground. The monkeys in Central and South America also differ in having less well-developed vision. This is reflected in the wiring in the visual system of the brain as well as in their <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1418\">polymorphic color vision<\/a><\/strong>. The genes that enable individuals to distinguish reds and yellows from blues and greens are on the X chromosome. Different genes code for being able to see different wavelengths of light so to distinguish between them you need to be heterozygous for seeing colour. The X chromosomes of platyrrhines each carry the genes for seeing one wavelength, so male platyrrhines (with only one X chromosome) are always dichromatic. Female platyrrhines can be dichromatic (if they are homozygous for one version of the colour vision gene) or trichromatic (if they are heterozygous) (Kawamura Et al. 2012). We currently know of two exceptions to this pattern among platyrrhines. Nocturnal owl monkeys are <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1420\">monochromatic<\/a><\/strong>, meaning that they cannot distinguish any colours. The other exception are howler monkeys, which have evolved to have two colour vision genes on each X chromosome. This means that both male and female howler monkeys are able to see reds and yellows. By contrast, catarrhine males and females are all trichromatic.<\/p>\n<figure style=\"width: 279px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image31-1.jpg\" alt=\"White-faced capuchin monkey.\" width=\"279\" height=\"190\" \/><figcaption class=\"wp-caption-text\">Figure 6.28: A capuchin monkey demonstrating a typical platyrrhine nose shape with round nostrils pointing outward on a flat nose. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:CARABLANCA_-_panoramio.jpg\">CARABLANCA - panoramio<\/a> by Manuel Velazquez is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/3.0\/legalcode\">CC BY 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Platyrrhines include the smallest of the monkeys, the marmosets and tamarins (Figure 6.29), all of which weigh less than one kilogram and live in cooperative family groups, wherein usually only one female reproduces and everyone else helps carry and raise the offspring. They are unusual primates in that they regularly produce twins. Marmosets and tamarins largely eat gums and saps, so these monkeys have evolved claw-like nails that enable them to cling to the sides of tree trunks like squirrels as well as special teeth that allow them to gnaw through bark. Except for the Goeldi\u2019s monkey, these small monkeys have one fewer molar than other platyrrhines, giving them a dental formula of 2:1:3:2.<\/p>\n<figure style=\"width: 428px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image32-1.jpg\" alt=\"Six marmoset and tamarin species.\" width=\"428\" height=\"470\" \/><figcaption class=\"wp-caption-text\">Figure 6.29: Clockwise from top right: golden-headed lion tamarin, pygmy marmoset, Goeldi\u2019s monkey, bare-eared marmoset, emperor tamarin, and common marmoset. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Callitrichinae_genus.jpg\">Callitrichinae genus<\/a> by Miguelrangeljr is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/deed.en\">CC BY-SA 3.0 License<\/a>. [Includes <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Wei%C3%9Fb%C3%BCschelaffe_(Callithrix_jacchus).jpg\">Wei\u00dfb\u00fcschelaffe_(Callithrix_jacchus)<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Raymond\">Raymond<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/\">CC BY-SA 4.0<\/a>;\u00a0 <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Leontopithecus_chrysomelas_(portrait).jpg\">Leontopithecus chrysomelas (portrait)<\/a> by Hans Hillewaert, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/\">CC BY-SA 4.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Emperor_Tamarin_portrait_2_edit1.jpg\">Emperor_Tamarin_portrait_2_edit1<\/a> by <a href=\"https:\/\/sites.google.com\/site\/thebrockeninglory\/\">Brocken Inaglory<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/\">CC BY-SA 4.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Dv%C3%A6rgsilkeabe_Callithrix_pygmaea.jpg\">Dv\u00e6rgsilkeabe_Callithrix_pygmaea<\/a> by Malene Thyssen (User <a href=\"https:\/\/da.wikipedia.org\/wiki\/User:Malene\">Malene<\/a>), <a href=\"https:\/\/en.wikipedia.org\/wiki\/GNU_Free_Documentation_License\">GNU Free Documentation License<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Mico_argentatus_(portrait).jpg\">Mico_argentatus_(portrait)<\/a> by Hans Hillewaert, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/\">CC BY-SA 4.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Titi_Monkey.jpg\">Titi Monkey<\/a> by Jeff Kubina, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/deed.en\">CC BY-SA 2.0<\/a>].]<\/figcaption><\/figure>\n<p class=\"import-Normal\">The largest platyrrhines are a family that include spider monkeys, woolly spider monkeys, woolly monkeys, and howler monkeys (Figure 6.30). These monkeys can weigh up to 9\u201315 kg and have evolved prehensile tails that can hold their entire body weight. It is among this group that we see semi-brachiators, like the spider monkey (see Figure 6.13). To make them more efficient in this form of locomotion, spider monkeys evolved to not have thumbs so that their hands work more like hooks that can easily let go of branches while swinging. Howler monkeys are another well-known member of this group, earning their name due to their loud calls, which can be heard miles away. To make these loud vocalizations, howler monkeys have a specialized vocal system that includes a large larynx and hyoid bone. Howler monkeys are the most folivorous of the platyrrhines and are known for spending a large portion of their day digesting their food.<\/p>\n<figure style=\"width: 458px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image33-1.jpg\" alt=\"Four platyrrhine species.\" width=\"458\" height=\"457\" \/><figcaption class=\"wp-caption-text\">Figure 6.30: Clockwise from top right: howler monkey, woolly monkey, woolly spider monkey, and spider monkey. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Atelidae_Family.jpg\">Atelidae Family<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Miguelrangeljr\">Miguelrangeljr<\/a> is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\">CC BY-SA 3.0 License<\/a>. [Includes <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Ateles_marginatus_(Sao_Paulo_zoo).jpg\">Ateles marginatus (Sao Paulo zoo)<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Miguelrangeljr\">Miguelrangeljr<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\">CC BY-SA 3.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Alouatta_caraya_male.JPG\">Alouatta caraya male<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Miguelrangeljr\">Miguelrangeljr<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\">CC BY-SA 3.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Lagothrix_lagotricha_(walking).jpg\">Lagothrix lagotricha (walking)<\/a> by Hans Hillewaert, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\">CC BY-SA 3.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Brachyteles_hypoxanthus2.jpg\">Brachyteles hypoxanthus2<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/42956474@N04\/with\/4133258867\/\">Paulo B. Chaves<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/legalcode\">CC BY 2.0<\/a>.]<\/figcaption><\/figure>\n<p class=\"import-Normal\">There are many other monkeys in Central and South America, including the gregarious capuchins (see Figure 6.28) and squirrel monkeys, the pair-living titi monkeys, and the nocturnal owl monkeys. There are also the seed-eating saki monkeys and uakaris. In many areas across Central and South America, multiple species of platyrrhines share the forests, with some even traveling together in association. According to molecular evidence, the diversity of platyrrhines that we see today seems to have originated about 25 million years ago (Schneider &amp; Sampaio 2015). Figure 6.31 summarizes the key traits of platyrrhines relative to the other infraorders of Haplorrhini.<\/p>\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<caption>Figure 6.31: Platyrrhini at a glance: Summary of the key traits we use to distinguish platyrrhines. Traits indicated with an * are those with exceptions detailed in the text. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\">Platyrrhini at a glance table (Figure 5.29)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/caption>\n<tbody>\n<tr class=\"a3-R\">\n<td class=\"a3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Platyrrhini traits<\/strong><\/p>\n<\/td>\n<\/tr>\n<tr class=\"a3-R\">\n<td class=\"a3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Flat nose with rounded nostrils pointing to the side<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Highly arboreal<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Less sexually dimorphic on average<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">2:1:3:3 dental formula*<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Polymorphic colour vision*<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h4 class=\"import-Normal\"><em>Infraorder Catarrhini of Asia and Africa <\/em><\/h4>\n<figure style=\"width: 191px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image34.jpg\" alt=\"Wolf\u2019s guenon.\" width=\"191\" height=\"287\" \/><figcaption class=\"wp-caption-text\">Figure 6.32: A Wolf\u2019s guenon demonstrating a typical catarrhine nose with teardrop-shaped nostrils close together and pointed downward. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Wolf&apos;s_Guenon_Picking_Up_Food_(19095137693).jpg\">Wolf's Guenon Picking Up Food (19095137693)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/8749778@N06\">Eric Kilby<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\">CC BY-SA 2.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Infraorder Catarrhini includes Superfamily Cercopithecoidea (the monkeys of Africa and Asia) and Superfamily Hominoidea (apes and humans). Nonhuman catarrhines are found all over Africa and South and Southeast Asia, with some being found as far north as Japan. The most northerly and southerly catarrhines are cercopithecoid monkeys. In contrast, apes are less tolerant of drier, more seasonal environments and so have a relatively restricted geographic range.<\/p>\n<p class=\"import-Normal\">Relative to other haplorrhine infraorders, catarrhines are distinguished by several characteristics. Catarrhines have a distinctive nose shape, with teardrop-shaped nostrils that are close together and point downward (Figure 6.32) and one fewer premolar than most other primates, giving us a dental formula of 2:1:2:3 (Figure 6.33). On average, catarrhines are the largest and most sexually dimorphic of all primates. Gorillas are the largest living primates, with males weighing up to 220 kg. The most sexually dimorphic of all primates are mandrills. Mandrill males not only have much more vibrant colouration than mandrill females but also have larger canines and can weigh up to three times more (Setchell Et al. 2001). The larger body size of catarrhines is related to the more terrestrial lifestyle of many members of this infraorder. In fact, the most terrestrial of living primates can be found in this group. Among all primates, vision is the most developed in catarrhines. Catarrhines independently evolved the same adaptation as howler monkeys in having each X chromosome with genes to distinguish both reds and yellows, so all male and female catarrhines are trichromatic, which is useful for these diurnal primates.<\/p>\n<figure style=\"width: 632px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image35-1.jpg\" alt=\"Platyrrhine, cercopithecoid, and hominoid mandibles.\" width=\"632\" height=\"331\" \/><figcaption class=\"wp-caption-text\">Figure 6.33: Catarrhines have two premolars whereas most other primate taxa (including platyrrhini) have three premolars. This image also shows one of the derived traits of cercopithecoids, their bilophodont molars, which differ from the more ancestral Y-5 molars of apes and humans. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\">Platyrrhini vs. Catarrhini dentition<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\">CC BY-NC-SA 4.0 License<\/a>. [Includes <a href=\"https:\/\/animaldiversity.org\/accounts\/Animalia\/specimens\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Cebus_apella\/lower_dorsal2216\/?start=135;f=subject::specimen::lower%20jaw\">Cebus apella (brown capuchin)<\/a> at Animal Diversity Web by <a href=\"https:\/\/animaldiversity.org\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Hylobates_syndactylus\/lower_dorsal0097\/\">Phil Myers<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\">CC BY-NC-SA 3.0<\/a>; <a href=\"https:\/\/animaldiversity.org\/accounts\/Animalia\/specimens\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Lophocebus_albigena\/lower_dorsal2060\/?start=525;f=subject::specimen::lower%20jaw\">Lophocebus albigena (gray-cheeked mangaby)<\/a> at Animal Diversity Web by <a href=\"https:\/\/animaldiversity.org\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Hylobates_syndactylus\/lower_dorsal0097\/\">Phil Myers<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\">CC BY-NC-SA 3.0<\/a>; <a href=\"https:\/\/animaldiversity.org\/accounts\/Primates\/specimens\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Hylobates_syndactylus\/lower_dorsal0097\/?start=105;f=subject::specimen::lower%20jaw\">Symphalangus syndactylus (siamang)<\/a> at Animal Diversity Web by <a href=\"https:\/\/animaldiversity.org\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Hylobates_syndactylus\/lower_dorsal0097\/\">Phil Myers<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\">CC BY-NC-SA 3.0<\/a>.]<\/figcaption><\/figure>\n<p class=\"import-Normal\">The two superfamilies of catarrhines\u2014Superfamily Cercopithecoidea, the monkeys of Africa and Asia, and Superfamily Hominoidea, which includes apes and humans\u2014are believed to have split about 32 million years ago based on molecular evidence (Pozzi Et al. 2014). This fits with the fossil record, which shows evidence of these lineages by about 25 million years ago (see Chapters 8-9).<\/p>\n<h4 class=\"import-Normal\"><em>Superfamily Cercopithecoidea of Africa and Asia<\/em><\/h4>\n<figure style=\"width: 285px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image36-1.jpg\" alt=\"Pinkish ischial callosities on a crested black macaque.\" width=\"285\" height=\"214\" \/><figcaption class=\"wp-caption-text\">Figure 6.34: The second derived trait of cercopithecoids are their ischial callosities, shown here on a crested black macaque. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Sulawesi_trsr_DSCN0572_v1.JPG\">Sulawesi trsr DSCN0572 v1<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Shankar_Raman\">T. R. Shankar Ramanis<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\">CC BY-SA 3.0 License.<\/a><\/figcaption><\/figure>\n<p>Compared to hominoids, cercopithecoids have an ancestral quadrupedal body plan with two key derived traits. The first derived trait of cercopithecoids is their <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1422\">bilophodont<\/a> <\/strong>molars (\u201cbi\u201d meaning two, \u201cloph\u201d referring to ridge, and \u201cdont\u201d meaning tooth). If you refer back to Figure 6.33, you will see how the molars of cercopithecoids have four cusps arranged in a square pattern and have two ridges connecting them. It is thought that this molar enabled these monkeys to eat a wide range of foods, thus allowing them to live in habitats that apes cannot. The other key derived trait that all cercopithecoids share is having <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1424\">ischial callosities<\/a> <\/strong>(Figure 6.34). The ischium is the part of your pelvis that you are sitting on right now (see Appendix A: Osteology). In cercopithecoids, this part of the pelvis has a flattened surface that, in living animals, has callused skin over it. These function as seat pads for cercopithecoids, who often sit above branches when feeding and resting.<\/p>\n<figure style=\"width: 359px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image37-1.png\" alt=\"Areas of Europe, Asia, Africa, and Australia where cercopithecoids live.\" width=\"359\" height=\"277\" \/><figcaption class=\"wp-caption-text\">Figure 6.35: Geographic distribution of the cercopithecoid monkeys. Catarrhines have the widest geographic distribution due to the success of cercopithecoids who are found all across subsaharan Africa and southern Asia. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\">Superfamily Cercopithecoidea map (Figure 5.33)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Elyssa Ebding at <a href=\"https:\/\/www.csuchico.edu\/geop\/geoplace\/index.shtml\">GeoPlace, California State University, Chico<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p>Cercopithecoid monkeys are the most geographically widespread group of nonhuman primates (Figure 6.35). Since their divergence from hominoids, this monkey group has increased in numbers and diversity due, in part, to their fast reproductive rates. On average, cercopithecoids will reproduce every one to two years, whereas hominoids will reproduce once every four to nine years, depending on the taxon.<\/p>\n<figure style=\"width: 180px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image38-1.jpg\" alt=\"Two silver leaf monkeys hold orange-haired infants.\" width=\"180\" height=\"240\" \/><figcaption class=\"wp-caption-text\">Figure 6.36: Silver leaf monkey infants are born with orange fur, dramatically contrasting the adult coat colour of their mothers. After a few months, the infants gradually change colour to that of their parents. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Silverleaf_Monkey_(Kuala_Lumpur).jpg\">Silverleaf Monkey (Kuala Lumpur)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/10815162@N07\">Andrea Lai<\/a> from Auckland, New Zealand, is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/legalcode\">CC BY 2.0 License.<\/a><\/figcaption><\/figure>\n<p>Cercopithecoidea is split into two groups, the leaf monkeys and the cheek-pouch monkeys. Both groups coexist in Asia and Africa; however, the majority of leaf monkey species live in Asia with only a few taxa in Africa. In contrast, only one genus of cheek-pouch monkey lives in Asia, and all the rest of them in Africa. As you can probably guess based on their names, the two groups differ in terms of diet. Leaf monkeys are primarily folivores, with some species eating a significant amount of seeds. Cheek-pouch monkeys tend to be more frugivorous or omnivorous, with one taxon, geladas, eating primarily grasses. The two groups also differ in some other interesting ways. Leaf monkeys tend to produce infants with <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1426\">natal coats<\/a><\/strong>\u2014infants whose fur is a completely different colour from their parents (Figure 6.36). Leaf monkeys are also known for having odd noses (Figure 6.37), and so they are sometimes called \u201codd-nosed monkeys.\u201d Cheek-pouch monkeys are able to pack food into their cheek pouches (Figure 6.38), thus allowing them to move to a location safe from predators or aggressive individuals of their own species where they can eat in peace.<\/p>\n<figure style=\"width: 408px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image39.jpg\" alt=\"Male proboscis monkey.\" width=\"408\" height=\"272\" \/><figcaption class=\"wp-caption-text\">Figure 6.37: Proboscis monkeys are one of several \u201codd-nosed\u201d leaf monkeys. Male proboscis monkeys, like this one, have large, pendulous noses, while females have much smaller noses. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Proboscis_monkey_(Nasalis_larvatus)_male_head.jpg\">Proboscis monkey (Nasalis larvatus) male head<\/a> by <a href=\"https:\/\/www.sharpphotography.co.uk\/\">Charles J Sharp<\/a> creator QS:P170,Q54800218 is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<figure style=\"width: 414px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image40-1.jpg\" alt=\"Bonnet macaque with full cheek pouches.\" width=\"414\" height=\"275\" \/><figcaption class=\"wp-caption-text\">Figure 6.38: This bonnet macaque has filled its cheek pouches with food, an adaptation that is useful in transporting food to a safer location to eat. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Bonnet_macaque_DSC_0893.jpg\">Bonnet macaque DSC 0893<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Shankar_Raman\">T. R. Shankar Raman<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<h4 class=\"import-Normal\"><em>Superfamily Hominoidea of Africa and Asia<\/em><\/h4>\n<figure style=\"width: 438px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image41.png\" alt=\"Areas of Europe, Asia, Africa, and Australia where hominoidea live.\" width=\"438\" height=\"339\" \/><figcaption class=\"wp-caption-text\">Figure 6.39: Geographic distribution of apes across Central and West Africa and Southeast Asia. Hominoids overlap geographically with cercopithecoid monkeys but have a lower tolerance for seasonal environments and so are found only in tropical forests across these regions. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\">Superfamily Hominoidea map (Figure 5.38)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Elyssa Ebding at <a href=\"https:\/\/www.csuchico.edu\/geop\/geoplace\/index.shtml\">GeoPlace, California State University, Chico<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Superfamily Hominoidea of Africa and Asia (Figure 6.39) includes the largest of the living primates: apes and humans. Whereas cercopithecoid monkeys have bilophodont molars, hominoids have the more ancestral <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1428\">Y-5 molars<\/a><\/strong>, which feature five cusps separated by a \u201cY\u201d-shaped groove pattern (see Figure 6.33). The Y-5 molar was present in the common ancestors of hominoids and cercopithecoids, thus it is the more ancestral molar pattern of the two. Hominoids differ the most from other primates in our body plans, due to the unique form of locomotion that hominoids are adapted for: brachiation (Figure 6.40).<\/p>\n<p>To successfully swing below branches, many changes to the body needed to occur. Hominoid arms are much longer than the legs to increase reach, and the lower back is shorter and less flexible to increase control when swinging. The torso, shoulders, and arms of hominoids have evolved to increase range of motion and flexibility (see again Figure 6.12). The clavicle, or collar bone, is longer to stabilize the shoulder joint out to the side, thus enabling us to rotate our arms 360 degrees. Hominoid rib cages are wider side to side and shallower front to back than those of cercopithecoids and we do not have tails, as tails are useful for balance when running on all fours but generally not useful while swinging. Hominoids also have modified ulnae, one of the two bones in the forearm (see Appendix A: Osteology). At the elbow end of the ulna, hominoids have a short <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1430\">olecranon process<\/a><\/strong>, which allows for improved extension in our arms. At the wrist end of the ulna, hominoids have a short <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1432\">styloid process<\/a><\/strong>, which enables us to have very flexible wrists, a trait critical for swinging. Both the olecranon process and styloid process are long in quadrupedal animals who carry much of their weight on their forelimbs when traveling and who therefore need greater stability rather than flexibility in those joints.<\/p>\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<caption>Figure 6.40: Quadrupedalism vs. brachiation: Summary of the key anatomical differences between a quadrupedal primate and one adapted for brachiation. To view these traits using photos of bones, check out the interactive skeletal websites in \u201cFurther Explorations\u201d below. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\">Quadrupedalism vs. Brachiation table (Figure 5.39)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/caption>\n<thead>\n<tr>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Quadrupedalism<\/strong><\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Brachiation<\/strong><\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"a4-R\">\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Arm length vs. leg length<\/strong><\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">About equal<\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Arms are longer<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a4-R\">\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Shoulder position<\/strong><\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">More on the front<\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Out to the side<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a4-R\">\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Ribcage shape<\/strong><\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Deep front-to-back<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Narrow side-to-side<\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Shallow front-to-back<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Wide side-to-side<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a4-R\">\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Length of lower back<\/strong><\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Long<\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Short<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a4-R\">\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Collar bone length<\/strong><\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Short<\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Long<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a4-R\">\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Ulnar olecranon process<\/strong><\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Long<\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Short<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a4-R\">\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Ulnar styloid process<\/strong><\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Long<\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Short<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a4-R\">\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Tail<\/strong><\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Short to long<\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">None<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p class=\"import-Normal\">Apes and humans also differ from other primates in behaviour and life history characteristics. Hominoids all seem to show some degree of female dispersal at sexual maturity but, as you will learn in Chapter 7, it is more common that males leave. Some apes show males dispersing in addition to females, but the hominoid tendency for female dispersal is a bit unusual among primates. Our superfamily is also characterized by the most extended life histories of all primates. All members of this group take a long time to grow and reproduce much less frequently compared to cercopithecoids. The slow pace of this life history is likely related to why hominoids have decreased in diversity since they first evolved. Figure 6.41 summarizes the key traits of Infraorder Catarrhini and its two superfamilies. Today, there are only five types of hominoids left: gibbons and siamangs, orangutans, gorillas, chimpanzees and bonobos, and humans.<\/p>\n<table class=\"aligncenter\">\n<caption>Figure 6.41a: Catarrhini at a glance: Summary of key traits of the Infraorder Catarrhini. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\">Catarrhini at a glance (Figure 5.40)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>. [Includes <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Duskyleafmonkey1.jpg\">Duskyleafmonkey1<\/a> by <a href=\"https:\/\/www.the-ninth.com\/about\">Robertpollai<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by\/3.0\/at\/deed.en\">CC BY 3.0 AT<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Male_Bornean_Orangutan_-_Big_Cheeks.jpg\">Male Bornean Orangutan - Big Cheeks<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/8749778@N06\">Eric Kilby<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\">CC BY-SA 2.0<\/a>.]<\/caption>\n<thead>\n<tr style=\"height: 22pt\">\n<td class=\"a5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\" colspan=\"2\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Infraorder Catarrhini<\/strong><\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"a5-R\" style=\"height: 22pt\">\n<td class=\"a5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\" colspan=\"2\">\n<p class=\"import-Normal\" style=\"text-align: center\">Downward facing, tear-drop shaped nostrils, close together<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Arboreal and more terrestrial taxa<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">On average, largest primates<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">On average, most sexually dimorphic taxonomic group<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">2:1:2:3 dental formula<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">All trichromatic<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<caption>Figure 6.41b: Characteristics used to distinguish between the two Catarrhini superfamilies. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\">Catarrhini at a glance (Figure 5.40)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>. [Includes <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Duskyleafmonkey1.jpg\">Duskyleafmonkey1<\/a> by <a href=\"https:\/\/www.the-ninth.com\/about\">Robertpollai<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by\/3.0\/at\/deed.en\">CC BY 3.0 AT<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Male_Bornean_Orangutan_-_Big_Cheeks.jpg\">Male Bornean Orangutan - Big Cheeks<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/8749778@N06\">Eric Kilby<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\">CC BY-SA 2.0<\/a>.]<\/caption>\n<thead>\n<tr>\n<td class=\"a5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong><img class=\"alignnone\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image42-1.jpg\" alt=\"Dusky leaf monkey\" width=\"248\" height=\"186\" \/><\/strong><strong>Superfamily Cercopithecoidea<\/strong><\/p>\n<\/td>\n<td class=\"a5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong><img class=\"alignnone\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image43-1.jpg\" alt=\"Orangutan\" width=\"274\" height=\"183\" \/><\/strong><strong>Superfamily Hominoidea<\/strong><\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"a5-R\">\n<td class=\"a5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Wide geographic distribution<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Bilophodont molars<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Ischial callosities<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Reproduce every 1\u20132 years<\/p>\n<\/td>\n<td class=\"a5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Tropical forests of Africa and Asia<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Y-5 molars<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Adaptations for brachiation<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Reproduce every 4\u20139 years<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h4 class=\"import-Normal\"><em>Family <\/em>Hylobatidae <em>of Southeast Asia<\/em><\/h4>\n<figure style=\"width: 441px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image44-1.jpg\" alt=\"Siamang with outstretched arms.\" width=\"441\" height=\"294\" \/><figcaption class=\"wp-caption-text\">Figure 6.42: Siamangs are the largest of the Hylobatidae family. They are all black with a throat sac that can become inflated to give out loud calls. Credit: <a href=\"https:\/\/www.flickr.com\/photos\/suneko\/373310729\/\">Shout (373310729)<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/suneko\/\">su neko<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/\">CC BY-SA 2.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">The number of genera in this group has been changing in recent years, but the taxa broadly encompasses gibbons and siamangs. Both are found across Southeast Asian tropical forests. Gibbons weigh, on average, about 13 pounds and tend to be more frugivorous, whereas siamangs are larger than gibbons and also more folivorous. Unlike the larger-bodied apes (orangutans, chimps, bonobos, and gorillas) who make nests to sleep in every night, gibbons and siamangs will develop callused patches on their ischium resembling ischial callosities. Gibbon species are quite variable in their colouration and markings, while siamangs are all black with big throat sacs that are used in their exuberant vocalizations (Figure 6.42). Both gibbons and siamangs live in pairs with very little sexual dimorphism, although males and females do differ in colouration in some gibbon species.<\/p>\n<h4 class=\"import-Normal\">Pongo<em> of Southeast Asia<\/em><\/h4>\n<p class=\"import-Normal\">The Genus <em>Pongo <\/em>refers to orangutans. These large red apes are found in Southeast Asia, with the two well-known species each living on the islands of Borneo and Sumatra. A third, very rare species, was recently discovered in Southern Sumatra (Nater Et al. 2017). Orangutans are highly frugivorous but will supplement their diet with leaves and bark when fruit is less available. As mentioned earlier, orangutans are the only diurnal, solitary taxon among primates and are extremely slow to reproduce, producing only one offspring about every seven to nine years. They are highly sexually dimorphic (Figure 6.43 a &amp; b), with fully developed, \u201cflanged\u201d males being approximately twice the size of females. These males have large throat sacs; long, shaggy coats; and cheek flanges. The skulls of male orangutans often feature a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1434\">sagittal crest<\/a><\/strong>, which is believed to function as additional attachment area for chewing muscles as well as a trait used in sexual competition (Balolia, Soligo, &amp; Wood 2017). An unusual feature of orangutan biology is <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1436\">male bimaturism<\/a><\/strong>. Male orangutans are known to delay maturation until one of the more dominant, flanged males disappears. The males that delay maturation are called \u201cunflanged\u201d males, and they can remain in this state for their entire life. Unflanged males resemble females in their size and appearance and will sneak copulations with females while avoiding the bigger, flanged males. Flanged and unflanged male orangutans represent alternative reproductive strategies, both of which successfully produce offspring (Utami Et al. 2002).<\/p>\n<p>&nbsp;<\/p>\n<\/div>\n<figure id=\"attachment_181-14\" aria-describedby=\"caption-attachment-181-14\" style=\"width: 1900px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-180 size-full\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/5.43.jpg\" alt=\"a. Female orangutan with infant. b. Male orangutan in a tree.\" width=\"1900\" height=\"800\" \/><figcaption id=\"caption-attachment-181-14\" class=\"wp-caption-text\">Figure 6.43: (a) A female orangutan eating fruit with her infant nearby and (b) a flanged adult male eating leaves. Male orangutans are about twice the size of females and have a longer coat length, cheek flanges, and throat sac. Credit: 6.43a. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Orang_Utan_(Pongo_pygmaeus)_female_with_baby_(8066259067).jpg\">Orang Utan (Pongo pygmaeus) female with baby (8066259067)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/65695019@N07\">Bernard DUPONT<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/\">CC BY-SA 2.0 Licence<\/a>. 6.43b. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Orangutan_-Zoologischer_Garten_Berlin-8a.jpg\">Orangutan -Zoologischer Garten Berlin-8a<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/37088680@N03\">David Forsman<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/\">CC BY 2.0 License<\/a>.<\/figcaption><\/figure>\n<div class=\"learning-objectives\">\n<h4 class=\"import-Normal\">Gorilla <em>of Africa<\/em><\/h4>\n<p class=\"import-Normal\">There are several species of gorillas that can be found across Central Africa. Gorilla males, like orangutan males, are about twice the size of female gorillas (Figures 6.44a &amp; b). When on the ground, gorillas use a form of quadrupedalism called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1438\">knuckle-walking<\/a><\/strong>, wherein the fingers are curled under and the weight is carried on the knuckles. Male gorillas have a large sagittal crest and large canines compared with females. Adult male gorillas are often called \u201csilverbacks\u201d because when they reach about twelve to thirteen years old, the hair on their backs turns silvery grey. Gorillas typically live in groups of one male and several females. Gorillas are considered folivorous, although some species can be more frugivorous depending on fruit seasonality (Remis 1997).<\/p>\n<\/div>\n<figure id=\"attachment_181-15\" aria-describedby=\"caption-attachment-181-15\" style=\"width: 1900px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-181 size-full\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/5.44.jpg\" alt=\"a. Female gorilla with offspring. b. Male gorilla.\" width=\"1900\" height=\"800\" \/><figcaption id=\"caption-attachment-181-15\" class=\"wp-caption-text\">Figure 6.44: (a) A female gorilla with her two offspring and (b) a silverback adult male. Male gorillas are about twice the size of females. They also differ from females in having a large sagittal crest and a silver back, which appears as they mature. Credit: 6.44a. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Enzo_naomi_echo.jpg\">Enzo naomi echo<\/a> by Zoostar is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/3.0\/legalcode\">CC BY 3.0 License<\/a>. 6.44b. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Male_gorilla_in_SF_zoo.jpg\">Male gorilla in SF zoo<\/a> by Brocken Inaglory is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<div class=\"learning-objectives\">\n<h4 class=\"import-Normal\">Pan<em> of Africa<\/em><\/h4>\n<figure style=\"width: 252px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image49-1.jpg\" alt=\"Bonobo looks away from the camera.\" width=\"252\" height=\"222\" \/><figcaption class=\"wp-caption-text\">Figure 6.45: Bonobo (Pan paniscus). You can see the distinctive hair-part on this bonobo. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Bonobo_male_Jasongo_15yo_Twycross_582a_(2014_11_14_01_04_18_UTC).jpg\">Bonobo male Jasongo 15yo Twycross 582a (2014 11 14 01 04 18 UTC)<\/a> by William H. Calvin is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<p>The Genus <em>Pan <\/em>includes two species: <em>Pan troglodytes <\/em>(the common chimpanzee) and <em>Pan paniscus <\/em>(the bonobo). These species are separated by the Congo River, with chimpanzees ranging across West and Central Africa and bonobos located in a restricted area south of the Congo River. Chimpanzees and bonobos both have broad, largely frugivorous diets.The two species differ morphologically in that bonobos are slightly smaller, have their hair parted down the middle of their foreheads, and are born with dark faces (Figure 6.45). In contrast, chimpanzees do not have the distinctive parted hair and are born with light faces that darken as they mature (Figure 6.46). Chimpanzees and bonobos live in a grouping called a fission-fusion community, which you will learn more about in Chapter 6. Both species are moderately sexually dimorphic, with males about 20% larger than females. When on the ground, chimpanzees and bonobos knuckle-walk like gorillas do.<\/p>\n<figure style=\"width: 418px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image50-1.jpg\" alt=\"Female chimpanzee with offspring in a tree.\" width=\"418\" height=\"278\" \/><figcaption class=\"wp-caption-text\">Figure 6.46: A common chimpanzee (Pan troglodytes) female (centre) and her offspring. Note the pink face of the youngest individual. Bonobos are born with dark-skinned faces, but chimpanzees are born with pink faces that darken with age. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Chimpanzees_in_Uganda_(5984913059).jpg\">Chimpanzees in Uganda (5984913059)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/57424551@N06\">USAID Africa Bureau<\/a> uploaded by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Elitre\">Elitre<\/a> is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\">public domain<\/a>.<\/figcaption><\/figure>\n<h4 class=\"import-Normal\">Homo<\/h4>\n<p class=\"import-Normal\">The last member of the Hominoidea to discuss is our own taxon, Genus <em>Homo<\/em>. Later chapters will discuss the many extinct species of <em>Homo<\/em>, but today there is only one living species of <em>Homo, <\/em>our own species, <em>sapiens<\/em>. While it is interesting to focus on how humans differ from apes in many aspects of our morphology, behaviour, and life history, one objective of this chapter, and of biological anthropology in general, is to understand our place in nature. This means looking for aspects of human biology that link us to the taxonomic diversity we have discussed. To that end, here we will focus on similarities humans share with other hominoids.<\/p>\n<p class=\"import-Normal\">Like other hominoids, humans lack a tail and possess upper-body adaptations for brachiation. While our lower body has been modified for a bipedal gait, we are still able to swing from branches and throw a baseball, all thanks to our mobile shoulder joint. Humans, like other hominoids, also have a Y-5 cusp pattern on our molars. All hominoids, including humans, have an extended life history, taking time to grow and develop, and reproducing slowly over a long life span. Lastly, while humans show a great deal of variation across cultures, many human societies show tendencies for female dispersal (Burton Et al. 1996).<\/p>\n<p class=\"import-Normal\">Among the hominoids, humans show particular affinities with other members of the African Clade, <em>Pan <\/em>and <em>Gorilla<\/em>. Humans share over 96% of our DNA with gorillas (Scally Et al. 2012), and over 98% with <em>Pan <\/em>(Ebersberger Et al. 2002). Even without this strong genetic evidence, the African Clade of hominoids share many morphological similarities, including having wide-set eye sockets and backward-sweeping cheekbones. Today, <em>Pan<\/em> and <em>Gorilla<\/em> knuckle-walk when on the ground, and it has been suggested the last common ancestor of chimpanzees, bonobos, gorillas, and humans did as well (Richmond, Begun, &amp; Strait 2001). Further, humans, chimpanzees, and bonobos all live in fission-fusion social groups characterized by shared behaviours, like male cooperation in hunting and territoriality, as well as tool use.<\/p>\n<div class=\"textbox\">\n<h2 class=\"import-Normal\">Special Topic: Primates in Culture and Religion<\/h2>\n<p class=\"import-Normal\">One of the best parts of teaching anthropology for me is getting to spend time watching primates at zoos. What I also find interesting is watching people watch primates. I have very often heard a parent and child walk up to a chimpanzee enclosure and exclaim \u201cLook at the monkeys!\u201d The parent and child often don\u2019t know that a chimpanzee is not a monkey, nor are they likely to know that chimpanzees share more than 98% of their DNA with us. What strikes me as significant is that, although most people do not know the difference between a monkey, an ape, and a lemur, they nonetheless recognize something in the animals as being similar to themselves. In fact, recognition of similarities between humans and other primates is very ancient, dating back far earlier than Linnaeus. For many of us, we only ever get to see primates in zoos and animal parks, but in many areas of the world, humans have coexisted with these animals for thousands of years. In areas where humans and primates have a long, shared history, nonhuman primates often play key roles in creation myths and cultural symbolism.<\/p>\n<p class=\"import-Normal\">Hamadryas baboons feature significantly in Ancient Egyptian iconography. Ancient Egyptian deities and beliefs transformed over time, as did the role of hamadryas baboons. Early on, baboons were thought to represent dead ancestors, and one monkey deity, called Babi or Baba, was thought to feed off of dead souls. Later, baboons became the totem animal for Thoth, the deity of science, writing, wisdom, and measurement, who also wrote the Book of the Dead. Sunbathing hamadryas baboons led ancient Egyptians to associate them with Ra, the sun god, who was the son of Thoth. During mummification, human organs were removed and put into canopic jars, one of which was topped with the head of the baboon-headed god, Hapi. Hamadryas baboons were also often kept as pets, as depicted in hieroglyphics, and occasionally mummified as well.<\/p>\n<p class=\"import-Normal\">On Madagascar, indris and aye-ayes play roles in the creation myths and omens of local people.There are many myths regarding the origins of indris and their relationship to humans, including one where two brothers living in the forest separated, with one brother leaving the forest and becoming a human while the other stayed in the forest to become the indri. Like humans, indris have long legs, no tail, and upright posture. They are considered sacred and are therefore protected. Unfortunately, the aye-aye is not treated with the same reverence. Because of their unusual appearance (see Figure 6.15), aye-ayes are seen as omens of death.They are usually killed when encountered because it is believed that someone will die if an aye-aye points at them.<\/p>\n<p class=\"import-Normal\">In India, monkeys play a key role in the Hindu religion. Hanuman, who resembles a monkey, is a key figure in the Ramayana. Hanuman is thought to be a guardian deity, and so local monkeys like Hanuman langurs and macaques are protected in India (Figure 6.47). In Thailand, where Hinduism is also practiced, the Hindu reverence for monkeys extends to \u201cmonkey feasts,\u201d where large quantities of food are spread out in gratitude to the monkeys for bringing good fortune.<\/p>\n<figure style=\"width: 308px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image51-1.jpg\" alt=\"Three macaques outside a temple in India.\" width=\"308\" height=\"261\" \/><figcaption class=\"wp-caption-text\">Figure 6.47: Because of important monkey-like figures in the Hindu religion, macaques are protected in India and often live near temples where they are fed by local peoples. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Macaque_India_4.jpg\">Macaque India 4<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Mosmas\">Thomas Schoch<\/a> (<a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Mosmas\">Mosmas<\/a>) is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">The people of Japan have coexisted with Japanese macaques for thousands of years, and so monkeys play key roles in both of the major Japanese religions. In the Shinto religion, macaques are thought of as messengers between the spirit world and humans, and monkey symbols are thought to be good luck. The other major religion in Japan is Buddhism, and monkeys play a role in symbolism of this religion as well. The \u201cThree Wise Monkeys\u201d who see no evil, speak no evil, and hear no evil derive from Buddhist iconography of monkeys.<\/p>\n<p class=\"import-Normal\">In Central and South America, monkeys feature often in Mayan and Aztec stories. In the Mayan creation story, the Popol Vuh, the \u201chero brothers,\u201d are actually a howler monkey and a spider monkey, who represent ancestors of humans in the story. In the Aztec religion, spider monkeys are associated with the god of arts, pleasure, and playfulness. A spider monkey is also represented in a Peruvian Nazca geoglyph, a large design made on the ground by moving rocks.<\/p>\n<p class=\"import-Normal\">In many of these regions today, the relationships between humans and nonhuman primates are complicated. The bushmeat and pet trades make these animals valuable at the expense of many animals\u2019 lives, and in some areas, nonhuman primates have become pests who raid crop fields and consume valuable foods. All of this has led to the development of a new subarea of anthropology called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1440\">Ethnoprimatology<\/a><\/strong>, which involves studying the political, economic, symbolic, and practical relationships between humans and nonhuman primates.This field highlights the particular challenges for humans of having to coexist with animals with whom we share so much in common. It also provides insight into some of the challenges facing primate conservation efforts (see Appendix B: Primate Conservation).<\/p>\n<\/div>\n<h2 class=\"import-Normal\">Summary<\/h2>\n<p class=\"import-Normal\">The Order Primates is a diverse and fascinating group of animals united in sharing a suite of characteristics\u2014visual specialization, grasping hands and feet, large brains, and extended life histories\u2014that differentiates us from other groups of mammals. In this chapter, we surveyed the major taxonomic groups of primates, discussing where humans fit among our close relatives as well as discovering that primates are interesting animals in their own right. We discussed a range of key traits used to distinguish between the many taxa of living primates, including dietary, locomotor, and behavioural characteristics. Because of our long, shared evolutionary history with these animals, nonhuman primates provide a crucial resource for understanding our current biology. In Chapter 7, you will discover the fascinating and complex social behaviours of nonhuman primates, which provide further insight into our evolutionary biology.<\/p>\n<\/div>\n<h2>Expand your view<\/h2>\n<p>For a deeper look into primate conservation and contemporary issues of endangerment\/extinction see <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/appendix-b-primate-conservation\/\">Appendix B<\/a><\/p>\n<p>&nbsp;<\/p>\n<div class=\"learning-objectives\">\n<div class=\"textbox shaded\">\n<h2 class=\"import-Normal\">Review Questions<\/h2>\n<ul>\n<li class=\"import-Normal\">Why does the field of anthropology, a field dedicated to the study of humans, include the study of nonhuman animals? What can we learn from nonhuman primates?<\/li>\n<li class=\"import-Normal\">Why is it important to try to place taxa into a clade classification rather than groupings based on grade? Can you think of an example?<\/li>\n<li class=\"import-Normal\">One of the important goals of an introductory biological anthropology course is to teach you about your place in nature. What is the full taxonomic classification of humans, and what are some of the traits we have of each of these categories?<\/li>\n<li class=\"import-Normal\">When you have seen primates in person, did you observe any facial expressions, behaviours, or physical traits that seemed familiar to you? If so, which ones and why?<\/li>\n<li class=\"import-Normal\">Draw out a tree showing the major taxonomic group of primates described here, making sure to leave room in between each level. Underneath each taxon, list some of the key features of this group so that you can compare traits between groups.<\/li>\n<\/ul>\n<\/div>\n<h2 class=\"import-Normal\">Key Terms<\/h2>\n<p class=\"import-Normal\"><strong>Activity pattern<\/strong>: Refers to the time of day an animal is typically active.<\/p>\n<p class=\"import-Normal\"><strong>African clade<\/strong>: A grouping that includes gorillas, chimpanzees, bonobos, humans, and their extinct relatives.<\/p>\n<p class=\"import-Normal\"><strong>Analogy<\/strong>: When two or more taxa exhibit similar traits that have evolved independently, the similar traits evolve due to similar selective pressures. (Also sometimes called convergent evolution, parallel evolution, or homoplasy.)<\/p>\n<p class=\"import-Normal\"><strong>Ancestral trait<\/strong>: A trait that has been inherited from a distant ancestor.<\/p>\n<p class=\"import-Normal\"><strong>Arboreal<\/strong>: A descriptor for an organism that spends most of its time in trees.<\/p>\n<p class=\"import-Normal\"><strong>Asian clade<\/strong>: A grouping that includes orangutang and their extinct relatives.<\/p>\n<p class=\"import-Normal\"><strong>Bilophodont<\/strong>: Molar pattern of cercopithecoid monkeys in which there are usually four cusps that are arranged in a square pattern and connected by two ridges.<\/p>\n<p class=\"import-Normal\"><strong>Bipedalism<\/strong>: Walking on two legs.<\/p>\n<p class=\"import-Normal\"><strong>Brachiation<\/strong>: A form of locomotion in which the organism swings below branches using the forelimbs.<\/p>\n<p class=\"import-Normal\"><strong>Bunodont<\/strong>: Low, rounded cusps on the cheek teeth.<\/p>\n<p class=\"import-Normal\"><strong>Canines<\/strong>: In most primates, these are the longest of the teeth, often conical in shape and used as a weapon against predators or others of their species.<\/p>\n<p class=\"import-Normal\"><strong>Cathemeral<\/strong>: Active throughout the 24-hour period.<\/p>\n<p class=\"import-Normal\"><strong>Clade<\/strong>: A grouping based on ancestral relationships; a branch of the evolutionary tree.<\/p>\n<p class=\"import-Normal\"><strong>Cusps<\/strong>: The bumps on the chewing surface of the premolars and molars, which can be quite sharp in some species.<\/p>\n<p class=\"import-Normal\"><strong>Dental formula<\/strong>: The number of each type of tooth in one quadrant of the mouth, written as number of incisors: canines: premolars: molars.<\/p>\n<p class=\"import-Normal\"><strong>Derived trait<\/strong>: A trait that has been recently modified, most helpful when assigning taxonomic classification.<\/p>\n<p class=\"import-Normal\"><strong>Diastema<\/strong>: A space between the teeth, usually for large canines to fit when the mouth is closed.<\/p>\n<p class=\"import-Normal\"><strong>Dichromatic<\/strong>: Being able to see only blues and greens.<\/p>\n<p class=\"import-Normal\"><strong>Diurnal<\/strong>: Active during the day.<\/p>\n<p class=\"import-Normal\"><strong>Dry nose<\/strong>: The nose and upper lip are separated and the upper lip can move independently; sometimes referred to as a \u201chairy\u201d or \u201cmobile\u201d upper lip.<\/p>\n<p class=\"import-Normal\"><strong>Ethnoprimatology<\/strong>: A subarea of anthropology that studies the complexities of human-primate relationships in the modern environment.<\/p>\n<p class=\"import-Normal\"><strong>Evolutionary trade-off<\/strong>: When an organism, which is limited in the time and energy it can put into aspects of its biology and behaviour, is shaped by natural selection to invest in one adaptation at the expense of another.<\/p>\n<p class=\"import-Normal\"><strong>Faunivorous<\/strong>: Having a diet consisting entirely of animal matter: insects, eggs, lizards, etc.<\/p>\n<p class=\"import-Normal\"><strong>Folivore<\/strong>: Having a diet consisting primarily of leaves.<\/p>\n<p class=\"import-Normal\"><strong>Fovea<\/strong>: A depressed area in the retina at the back of the eye containing a concentration of cells that allow one to focus on objects very close to one\u2019s face.<\/p>\n<p class=\"import-Normal\"><strong>Frugivore<\/strong>: Having a diet consisting primarily of fruit.<\/p>\n<p class=\"import-Normal\"><strong>Generalized trait<\/strong>: A trait that is useful for a wide range of tasks.<\/p>\n<p class=\"import-Normal\"><strong>Grade<\/strong>: A grouping based on overall similarity in lifestyle, appearance, and behaviour.<\/p>\n<p class=\"import-Normal\"><strong>Grooming claw<\/strong>: A claw present on the second pedal digit in strepsirrhines.<\/p>\n<p class=\"import-Normal\"><strong>Gummivore<\/strong>: Having a diet consisting primarily of gums and saps.<\/p>\n<p class=\"import-Normal\"><strong>Heterodont<\/strong>: Having different types of teeth.<\/p>\n<p class=\"import-Normal\"><strong>Homology<\/strong>: When two or more taxa share characteristics because they inherited them from a common ancestor.<\/p>\n<p class=\"import-Normal\"><strong>Hone<\/strong>: When primates sharpen their canines by wearing them on adjacent teeth.<\/p>\n<p class=\"import-Normal\"><strong>Incisors<\/strong>: The spatula-shaped teeth at the front of the mouth.<\/p>\n<p class=\"import-Normal\"><strong>Insectivore<\/strong>: Having a diet consisting primarily of insects.<\/p>\n<p class=\"import-Normal\"><strong>Ischial callosities<\/strong>: Modified seat bones of the pelvis that are flattened and over which calluses form; function as seat pads for sitting and resting atop branches.<\/p>\n<p class=\"import-Normal\"><strong>Knuckle-walking<\/strong>: A form of quadrupedal movement used by <em>Gorilla<\/em> and <em>Pan<\/em> when on the ground, wherein the front limbs are supported on the knuckles of the hands.<\/p>\n<p class=\"import-Normal\"><strong>Life history<\/strong>: Refers to an organism\u2019s pace of growth, reproduction, lifespan, etc.<\/p>\n<p class=\"import-Normal\"><strong>Locomotion<\/strong>: How an organism moves around.<\/p>\n<p class=\"import-Normal\"><strong>Male bimaturism<\/strong>: Refers to the alternative reproductive strategies in orangutans in which males can delay maturation, sometimes indefinitely, until a fully mature, \u201cflanged\u201d male disappears.<\/p>\n<p class=\"import-Normal\"><strong>Molars<\/strong>: The largest teeth at the back of the mouth; used for chewing. In primates, these teeth usually have between three and five cusps.<\/p>\n<p class=\"import-Normal\"><strong>Monochromatic<\/strong>: Being able to see only in shades of light to dark, no colour.<\/p>\n<p class=\"import-Normal\"><strong>Monomorphic<\/strong>: When males and females of a species do not exhibit significant sexual dimorphism.<\/p>\n<p class=\"import-Normal\"><strong>Natal coat<\/strong>: Refers to the contrasting fur colour of baby leaf monkeys compared to adults.<\/p>\n<p class=\"import-Normal\"><strong>Nocturnal<\/strong>: Active at night.<\/p>\n<p class=\"import-Normal\"><strong>Olecranon process<\/strong>: Bony projection at the elbow end of the ulna.<\/p>\n<p class=\"import-Normal\"><strong>Opposable thumb <\/strong>or <strong>opposable big toe<\/strong>: Having thumbs and toes that go in a different direction from the rest of the fingers, allows for grasping with hands and feet.<\/p>\n<p class=\"import-Normal\"><strong>Pentadactyly<\/strong>: Having five digits or fingers and toes.<\/p>\n<p class=\"import-Normal\"><strong>Polymorphic colour vision<\/strong>: A system in which individuals of a species vary in their abilities to see colour. In primates, it refers to males being dichromatic and females being either trichromatic or dichromatic.<\/p>\n<p class=\"import-Normal\"><strong>Postorbital bar<\/strong>: A bony ring that surrounds the eye socket, open at the back.<\/p>\n<p class=\"import-Normal\"><strong>Postorbital closure\/plate<\/strong>: A bony plate that provides protection to the side and back of the eye.<\/p>\n<p class=\"import-Normal\"><strong>Prehensile tail<\/strong>: A tail that is able to hold the full body weight of an organism, which often has a tactile pad on the underside of the tip for improved grip.<\/p>\n<p class=\"import-Normal\"><strong>Premolars<\/strong>: Smaller than the molars, used for chewing. In primates, these teeth usually have one or two cusps.<\/p>\n<p class=\"import-Normal\"><strong>Quadrupedalism<\/strong>: Moving around on all fours.<\/p>\n<p class=\"import-Normal\"><strong>Rhinariums<\/strong>: Wet noses; resulting from naked skin of the nose which connects to the upper lip and smell-sensitive structures along the roof of the mouth.<\/p>\n<p class=\"import-Normal\"><strong>Sagittal crest<\/strong>: A bony ridge along the top\/middle of the skull, used for attachment of chewing muscles.<\/p>\n<p class=\"import-Normal\"><strong>Scent marking<\/strong>: The behaviour of rubbing scent glands or urine onto objects as a way of communicating with others.<\/p>\n<p class=\"import-Normal\"><strong>Semi-brachiation<\/strong>: A form of locomotion in which an organism swings below branches using a combination of forelimbs and prehensile tail.<\/p>\n<p class=\"import-Normal\"><strong>Sexually dimorphic<\/strong>: When a species exhibits sex differences in morphology, behaviour, hormones, and\/or colouration.<\/p>\n<p class=\"import-Normal\"><strong>Shearing crests<\/strong>: Sharpened ridges that connect cusps on a bilophodont molar.<\/p>\n<p class=\"import-Normal\"><strong>Specialized trait<\/strong>: A trait that has been modified for a specific purpose.<\/p>\n<p class=\"import-Normal\"><strong>Styloid process of ulna<\/strong>: A bony projection of the ulna at the end near the wrist.<\/p>\n<p class=\"import-Normal\"><strong>Tactile pads<\/strong>: Sensitive skin at the fingertips for sense of touch. Animals with a prehensile tail have a tactile pad on the underside of the tail as well.<\/p>\n<p class=\"import-Normal\"><strong>Tapetum lucidum<\/strong>: Reflecting layer at the back of the eye that magnifies light.<\/p>\n<p class=\"import-Normal\"><strong>Terrestrial<\/strong>: A descriptor for an organism that spends most of its time on the ground.<\/p>\n<p class=\"import-Normal\"><strong>Tetrachromatic<\/strong>: Having the ability to see reds, yellows, blues, greens, and ultraviolet.<\/p>\n<p class=\"import-Normal\"><strong>Tooth comb<\/strong> or <strong>dental comb<\/strong>: A trait of the front, lower teeth of strepsirrhines in which, typically, the four incisors and canines are long and thin and protrude outward.<\/p>\n<p class=\"import-Normal\"><strong>Trichromatic colour vision<\/strong>: Being able to distinguish yellows and reds in addition to blues and greens.<\/p>\n<p class=\"import-Normal\"><strong>Vertical clinging and leaping<\/strong>: A locomotor pattern in which animals are oriented upright while clinging to vertical branches, push off with hind legs, and land oriented upright on another vertical branch.<\/p>\n<p class=\"import-Normal\"><strong>Y-5 molar<\/strong>: Molar cusp pattern in which five molar cusps are separated by a \u201cY\u201d-shaped groove pattern.<\/p>\n<h2 class=\"import-Normal\">For Further Exploration<\/h2>\n<p class=\"import-Normal\"><a href=\"https:\/\/animaldiversity.org\/accounts\/Primates\/specimens\/\">Animal Diversity Web<\/a>. This website is hosted by the Zoology Department at the University of Michigan. It has photographs of skulls, teeth, hands, arms, and feet of many primate species.<\/p>\n<p class=\"import-Normal\"><a href=\"https:\/\/www.eskeletons.org\">eSkeletons<\/a>. This website is hosted by the Department of Anthropology at University of Texas, Austin. It is an interactive website where you can compare specific bones from different species of primates.<\/p>\n<p class=\"import-Normal\">Fleagle, John G. 2013. <em>Primate Adaptation and Evolution<\/em>. Third edition. San Diego: Academic Press.<\/p>\n<p class=\"import-Normal\">Fuentes, Agust\u00edn, and Kimberley J. Hockings. 2010. \u201cThe Ethnoprimatological Approach in Primatology.\u201d <em>American Journal of Primatology<\/em> 72 (10): 841\u2013847.<\/p>\n<p class=\"import-Normal\">Rowe, Noel. 1996. <em>Pictorial Guide to the Living Primates<\/em>. Charlestown, RI: Pogonias Press.<\/p>\n<p class=\"import-Normal\">Whitehead, Paul F., William K. Sacco, and Susan B. Hochgraf. 2005. <em>A Photographic Atlas for Physical Anthropology<\/em>. Englewood, CO: Morton Publishing.<\/p>\n<h2>References<\/h2>\n<p class=\"import-Normal\">Balolia, Katharine L., Christophe Soligo, and Bernard Wood. 2017. \u201cSagittal Crest Formation in Great Apes and Gibbons.\u201d <em>Journal of Anatomy<\/em> 230 (6): 820\u2013832.<\/p>\n<p class=\"import-Normal\">Bininda-Emonds, Olaf R., Marcel Cardillo, Kate E. Jones, Ross D. E. MacPhee, Robin M. D. Beck, Richard Grenyer, Samantha A. Price, Rutger A. Vos, John L. Gittleman, and Andy Purvis. 2007. \u201cThe Delayed Rise of Present-Day Mammals.\u201d <em>Nature<\/em> 446 (7135): 507\u2013512.<\/p>\n<p class=\"import-Normal\">Burton, Michael L., Carmella C. Moore, John W. M. Whiting, A. Kimball Romney, David F. Aberle, Juan A. Barcelo, Malcolm M. Dow, et al. 1996. \u201cRegions Based on Social Structure.\u201d <em>Current Anthropology<\/em> 37 (1): 87\u2013123.<\/p>\n<p class=\"import-Normal\">Chivers, David J., and C. M. Hladik. 1980. \u201cMorphology of the Gastrointestinal Tract in Primates: Comparisons with Other Mammals in Relation to Diet.\u201d <em>Journal of Morphology<\/em> 166 (3): 337\u2013386.<\/p>\n<p class=\"import-Normal\">Clutton-Brock, T. H., and Paul H. Harvey. 1980. \u201cPrimates, Brains, and Ecology.\u201d <em>Journal of Zoology<\/em> 190 (3): 309\u2013323.<\/p>\n<p class=\"import-Normal\">Dunbar, Robin I. M. 1998. \u201cThe Social Brain Hypothesis.\u201d <em>Evolutionary Anthropology<\/em> 6 (5): 178\u2013190.<\/p>\n<p class=\"import-Normal\">Ebersberger, Ingo, Dirk Metzler, Carsten Schwarz, and Svante P\u00e4\u00e4bo. 2002. \u201cGenomewide Comparison of DNA Sequences Between Humans and Chimpanzees.\u201d <em>American Journal of Human Genetics<\/em> 70 (6): 1490\u20131497.<\/p>\n<p class=\"import-Normal\">Jameson, Natalie M., Zhuo-Cheng Hou, Kirstin N. Sterner, Amy Weckle, Morris Goodman, Michael E. Steiper, and Derek E. Wildman. 2011. \u201cGenomic Data Reject the Hypothesis of a Prosimian Primate Clade.\u201d <em>Journal of Human Evolution<\/em> 61 (3): 295\u2013305.<\/p>\n<p class=\"import-Normal\">Kawamura, Shoji, Chihiro Hiramatsu, Amanda D. Melin, Colleen M. Schaffner, Filippo Aureli, and Linda M. Fedigan. 2012. \u201cPolymorphic Color Vision in Primates: Evolutionary Considerations.\u201d In <em>Post-Genome Biology of Primates<\/em>, edited by H. Irai, H. Imai, and Y. Go, 93\u2013120. Tokyo: Springer.<\/p>\n<p class=\"import-Normal\">Matsui, Atsushi, Felix Rakotondraparany, Isao Munechika, Masami Hasegawa, and Satoshi Horai. 2009. \u201cMolecular Phylogeny and Evolution of Prosimians Based on Complete Sequences of Mitochondrial DNAs.\u201d <em>Gene<\/em> 441 (1\u20132): 53\u201366.<\/p>\n<p class=\"import-Normal\">Nater, Alexander, Maja P. Mattle-Greminger, Anton Nurcahyo, Matthew G. Nowak, Marc de Manuel, Tariq Desai, Colin Groves, et al. 2017. \u201cMorphometric, Behavioral, and Genomic Evidence for a New Orangutan Species.\u201d <em>Current Biology<\/em> 27 (22): 3487\u20133498.<\/p>\n<p class=\"import-Normal\">Pozzi, Luca, Jason A. Hodgson, Andrew S. Burrell, Kirstin N. Sterner, Ryan L. Raaum, and Todd R. Disotell. 2014. \u201cPrimate Phylogenetic Relationships and Divergence Dates Inferred from Complete Mitochondrial Genomes.\u201d <em>Molecular Phylogenetics and Evolution<\/em> 75: 165\u2013183.<\/p>\n<p class=\"import-Normal\">Remis, Melissa J. 1997. \u201cWestern Lowland Gorillas (<em>Gorilla gorilla gorilla<\/em>) as Seasonal Frugivores: Use of Variable Resources.\u201d <em>American Journal of Primatology<\/em> 43 (2): 87\u2013109.<\/p>\n<p class=\"import-Normal\">Richmond, Brian G., David R. Begun, and David S. Strait. 2001. \u201cOrigin of Human Bipedalism: The Knuckle\u2010Walking Hypothesis Revisited.\u201d <em>American<\/em> <em>Journal of Physical Anthropology<\/em> 116 (S33): 70\u2013105.<\/p>\n<p class=\"import-Normal\">Robson, Shannen L., Carel P. van Schaik, and Kristen Hawkes. 2006. \u201cThe Derived Features of Human Life History.\u201d In <em>The Evolution of Human Life History, edited by Kristen Hawkes and Richard R. Paine, <\/em>17\u201344. Santa Fe: SAR Press.<\/p>\n<p class=\"import-Normal\">Scally, Aylwyn, Julien Y. Dutheil, LaDeana W. Hillier, Gregory E. Jordan, Ian Goodhead, Javier Herrero, Asger Hobolth, et al. 2012. \u201cInsights into Hominid Evolution from the Gorilla Genome Sequence.\u201d <em>Nature<\/em> 483 (7388): 169\u2013175.<\/p>\n<p class=\"import-Normal\">Schneider, Horacio, and Iracilda Sampaio. 2015. \u201cThe Systematics and Evolution of New World Primates: A Review.\u201d <em>Molecular Phylogenetics and Evolution<\/em> 82 (B): 348\u2013357.<\/p>\n<p class=\"import-Normal\">Setchell, Joanna M., Phyllis C. Lee, E. Jean Wickings, and Alan F. Dixson. 2001. \u201cGrowth and Ontogeny of Sexual Size Dimorphism in the Mandrill (<em>Mandrillus sphinx<\/em>).\u201d <em>American Journal of Physical Anthropology<\/em> 115 (4): 349\u2013360.<\/p>\n<p class=\"import-Normal\">Utami, Sri Suci, Beno\u00eet Goossens, Michael W. Bruford, Jan R. de Ruiter, and Jan A. R. A. M. van Hooff. 2002. \u201cMale Bimaturism and Reproductive Success in Sumatran Orang-utans.\u201d <em>Behavioral Ecology<\/em> 13 (5): 643\u2013652.<\/p>\n<p class=\"import-Normal\">Vasey, Natalie. 2006. \u201cImpact of Seasonality and Reproduction on Social Structure, Ranging Patterns, and Fission\u2013Fusion Social Organization in Red Ruffed Lemurs.\u201d In <em>Lemurs: Ecology and Adaptation<\/em>, edited by Lisa Gould and Michelle L. Sauther, 275\u2013304. New York: Springer.<\/p>\n<p class=\"import-Normal\">Wright, Patricia C. 1999. \u201cLemur Traits and Madagascar Ecology: Coping with an Island Environment.\u201d <em>American Journal of Physical Anthropology<\/em> 110 (S29): 31\u201372.<\/p>\n<h2>Acknowledgements<\/h2>\n<p class=\"import-Normal\">The author would very much like to thank the editors for the opportunity to contribute to this textbook, along with anonymous reviewers who provided useful feedback on earlier drafts of this chapter. She would particularly like to thank Karin Enstam Jaffe for her support and encouragement during the writing of this chapter and its revision. Most of all, the author would like to thank all of the Introduction to Biological Anthropology students that she has had over the years who have listened to her lecture endlessly on these animals that she finds so fascinating and who have helped her to hone her pedagogy in a field that she loves.<\/p>\n<\/div>\n<\/div>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1695_1858\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1695_1858\"><div tabindex=\"-1\"><div class=\"__UNKNOWN__\">\n<div class=\"textbox\">\n<p>Learn more about <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/about-the-authors\/\">authors and editors<\/a>,<a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/student-contributors\/\"> Hess' student contributions<\/a>, and <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/versioning-history\/\">versioning history<\/a>.<\/p>\n<\/div>\n<div class=\"textbox textbox--learning-objectives\">\n<header class=\"textbox__header\">\n<h2 class=\"textbox__title\">Learning Objectives<\/h2>\n<\/header>\n<div class=\"textbox__content\">\n<ul>\n<li class=\"import-Normal\">Describe how studying nonhuman primates is important in anthropology.<\/li>\n<li class=\"import-Normal\">Compare two ways of categorizing taxa: grades and clades.<\/li>\n<li class=\"import-Normal\">Define different types of traits used to evaluate primate taxa.<\/li>\n<li class=\"import-Normal\">Identify key ways that primates differ from other mammals.<\/li>\n<li class=\"import-Normal\">Distinguish between the major primate taxa using their key characteristics.<\/li>\n<li class=\"import-Normal\">Describe your place in nature by learning your taxonomic classification.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<p class=\"import-Normal\">You may be wondering why a field dedicated to the study of humans includes discussions of nonhuman animals. Our primary goal in biological anthropology is to understand how humans are similar to and different from the rest of the natural world, why we have the traits we have, and how we got to be the way we are. But to fully grasp our place in nature, we must look to our closest living relatives, the nonhuman primates. In this chapter, we focus on the organization and diversity within the Order Primates.<\/p>\n<h2 class=\"import-Normal\">Studying Primates in Biological Anthropology<\/h2>\n<p class=\"import-Normal\">Primates are one of at least twenty Orders belonging to the Class Mammalia, and probably one of the oldest. One genetic estimate puts the origin of primates at approximately 91 million years ago (mya), predating the extinction of the dinosaurs (Bininda-Emonds Et al. 2007). Today, the Order Primates is a diverse group of animals that includes lemurs and lorises, tarsiers, monkeys, apes, and humans, all of which are united in sharing a suite of anatomical, behavioural, and life history characteristics. While nonhuman primates are fascinating animals in their own right, their close relationship to humans makes them ideal for studying humans via <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_944\">homology<\/a>, <\/strong>looking at traits that are shared between taxa because they inherited the trait from a common ancestor. For example, humans (genus <em>Homo<\/em>) and chimpanzees (genus <em>Pan<\/em>) both share the trait of male cooperation in hunting. This trait\u2014along with many others that chimpanzees and humans share\u2014is likely homologous<em>, <\/em>meaning it was probably passed down from the last common ancestor of <em>Homo<\/em> and <em>Pan, <\/em>which lived about 6\u20138 million years ago.<\/p>\n<p class=\"import-Normal\">Nonhuman primates also make excellent comparators for learning about humans via <strong>analogy<\/strong>. Many nonhuman primates live in environments similar to those in which our ancestors lived and therefore exhibit traits similar to what we see in humans. For example, baboons and humans both have long legs. In humans, this is because about 1.7 million years ago, our ancestors moved into savanna habitats where longer legs helped them move more efficiently over long distances. Baboons, who also live in savanna habitats, independently evolved longer arms and legs for the same reason\u2014to be able to cover more ground, more efficiently. This means that having long legs is an analogous trait in baboons and humans: \u2014that is, this adaptation evolved independently in the two species but for the same purpose. Using homology and analogy, our closest living relatives provide the critical context in which to understand human biology, morphology, and behaviour. It is only by studying how humans compare with our primate relatives that we can fully comprehend our place in nature.<\/p>\n<h3 class=\"import-Normal\"><strong>Ways of Organizing Taxa<\/strong><\/h3>\n<p class=\"import-Normal\">You learned in Chapter 2 about Linnaeus and the hierarchical nature of taxonomic classification. Our goal in classifying taxa is to create categories that reflect clade relationships. A <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1116\">clade<\/a> <\/strong>is a grouping of organisms based on relatedness that reflects a branch of the evolutionary tree. Clade relationships are determined using traits shared by groups of taxa as well as genetic similarities. An example of a clade would be a grouping that includes humans, chimpanzees, bonobos, and gorillas (Figure 6.1). These taxa are in what is referred to as the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1118\">African clade<\/a><\/strong> of hominoids (a taxonomic group you will learn about later in this chapter). The African clade grouping reflects how humans, chimpanzees, bonobos, and gorillas all share a more recent ancestor with each other than any of them do with other species\u2014that is, we are on the same branch of the evolutionary tree. We know members of the African clade are most closely related based on shared morphological traits as well as genetic similarities. Excluded from this grouping is the orangutan, which is considered a member of the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1120\">Asian clade<\/a><\/strong> of hominoids.<\/p>\n<figure style=\"width: 800px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2023\/06\/image1-3.jpg\" alt=\"Diagram shows large-bodied hominoids grouped by grade or clade.\" width=\"800\" height=\"358\" \/><figcaption class=\"wp-caption-text\">Figure 6.1: Grades vs. Clades. A grade grouping of apes places orangutans, gorillas, chimpanzees, and bonobos together based on their similar appearance and lifestyle, but excludes humans. Clade classification is based on shared derived traits and genetic evidence (both reflecting close evolutionary relationships). A clade grouping of apes places humans with gorillas, chimpanzees, and bonobos., whereas orangutans are separated. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\" target=\"_blank\">Grades vs. clades comparison (Figure 5.12)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\" target=\"_blank\">CC BY-NC-SA 4.0 License<\/a>. [Includes <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Orangutan_on_a_tree_(Unsplash).jpg\" target=\"_blank\">Orangutan on a tree (Unsplash)<\/a> by Dawn Armfield, <a href=\"https:\/\/creativecommons.org\/publicdomain\/zero\/1.0\/legalcode\" target=\"_blank\">public domain (CC0 1.0)<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Gorilla_Profile_(17997840570).jpg\" target=\"_blank\">Gorilla Profile (17997840570)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/100915417@N07\" target=\"_blank\">Charlie Marshall<\/a> from Bristol UK, modified (cropped), <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/legalcode\" target=\"_blank\">CC BY 2.0 License<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Chimpanzee_(14679767561).jpg\" target=\"_blank\">Chimpanzee (14679767561)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/120374925@N06\" target=\"_blank\">Magnus Johansson<\/a>, modified (cropped), <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\" target=\"_blank\">CC BY-SA 2.0<\/a>; <a href=\"https:\/\/pixabay.com\/photos\/pointing-finger-hand-pointing-1922074\/\" target=\"_blank\">Pointing finger (1922074)<\/a> by <a href=\"https:\/\/pixabay.com\/users\/truthseeker08-2411480\/\" target=\"_blank\">truthseeker08<\/a>, <a href=\"https:\/\/pixabay.com\/service\/terms\/#license\" target=\"_blank\">Pixabay License<\/a>.]<\/figcaption><\/figure>\n<p class=\"import-Normal\">In contrast, <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1122\">grades<\/a> <\/strong>are groupings that reflect levels of adaptation or overall similarity and not necessarily evolutionary relationships. An example of a grade would be placing orangutans, gorillas, bonobos, and chimpanzees into a group, and excluding humans. Grouping in this way is based on the superficial similarities of the apes in being large-bodied, having lots of body hair, living in tropical forests, climbing and sleeping in trees, and so on. According to these criteria, humans seem to be unusual in that we differ in our morphology, behaviour, and ecology. Separating humans from the large-bodied apes is the system that was used historically. We now know that grouping orangutans, gorillas, bonobos, and chimpanzees and excluding humans does not accurately reflect our true evolutionary relationships. Since our goal in taxonomic classification is to organize animals to reflect their evolutionary relationships, we prefer to use clade classifications.<\/p>\n<h3 class=\"import-Normal\"><strong>Types of Traits<\/strong><\/h3>\n<p class=\"import-Normal\">When evaluating relationships between taxa, we use key traits that allow us to determine which species are most closely related to one another. Traits can be either ancestral or derived. <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1124\">Ancestral traits<\/a><\/strong> are those that a taxon has because it has inherited the trait from a distant ancestor. For example, all primates have body hair because we are mammals and all mammals share an ancestor hundreds of millions of years ago that had body hair. This trait has been passed down to all mammals from a shared ancestor, so all mammals alive today have body hair. <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1126\">Derived traits<\/a><\/strong> are those that have been more recently altered. This type of trait is most useful when we are trying to distinguish one group from another because derived traits tell us which taxa are more closely related to each other. For example, humans walk on two legs.The many adaptations that humans possess that allow us to move in this way evolved after humans split from the Genus <em>Pan<\/em>. This means that when we find fossil taxa that share derived traits for walking on two legs, we can conclude that they are likely more closely related to humans than to chimpanzees and bonobos<em>. <\/em><\/p>\n<p class=\"import-Normal\">There are a couple of other important points about ancestral and derived traits that will become apparent as we discuss primate diversity. First, the terms <em>ancestral<\/em> and <em>derived<\/em> are relative terms, meaning that a trait can be either one depending on the taxa being compared. For example, in the previous paragraph, body hair was used as an example for an ancestral trait among primates. All mammals have body hair because we share a distant ancestor who had this trait. The presence of body hair therefore doesn\u2019t allow you to distinguish whether monkeys are more closely related to apes or lemurs because they all share this trait. However, if we are comparing mammals to birds and fish, then body hair becomes a derived trait of mammals. It evolved after mammals diverged from birds and fish, and it tells us that all mammals are more closely related to each other than they are to birds or fish.The second important point is that very often when one lineage splits into two, one taxon will stay more similar to the last common ancestor in retaining more ancestral traits, whereas the other lineage will usually become more different from the last common ancestor by developing more derived traits. This will become very apparent when we discuss the two suborders of primates, Strepsirrhini and Haplorrhini. When these two lineages diverged, strepsirrhines retained more ancestral traits (those present in the earliest primates) and haplorrhines developed more derived traits (became more different from ancestral primates).<\/p>\n<p class=\"import-Normal\">There are two other types of traits that will be relevant to our discussions here: generalized and specialized traits. <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1128\">Generalized traits<\/a> <\/strong>are those characteristics that are useful for a wide range of things. Having <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1138\">opposable thumbs<\/a><\/strong> that go in a different direction than the rest of your fingers is a very useful, generalized trait. You can hold a pen, grab a branch, peel a banana, or text your friends all thanks to your opposable thumbs! <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1130\">Specialized traits<\/a> <\/strong>are those that have been modified for a specific purpose. These traits may not have a wide range of uses, but they will be very efficient at their job. Hooves in horses are a good example of a specialized trait: they allow horses to run quickly on the ground on all fours. You can think of generalized traits as a Swiss Army knife, useful for a wide range of tasks but not particularly good at any one of them. That is, if you\u2019re in a bind, then a Swiss Army knife can be very useful to cut a rope or fix a loose screw, but if you were going to build furniture or fix a kitchen sink, then you\u2019d want specialized tools for the job. As we will see, most primate traits tend to be generalized.<\/p>\n<h2 class=\"import-Normal\">What Makes Something a Primate?<\/h2>\n<p class=\"import-Normal\">The Order Primates is distinguished from other groups of mammals in having a <em>suite of characteristics<\/em>. This means that there is no individual trait that you can use to instantly identify an animal as a primate; instead, you have to look for animals that possess a collection of traits. What this also means is that each individual trait we discuss may be found in nonprimates, but if you see an animal that has most or all of these traits, there is a good chance it is a primate.<\/p>\n<p class=\"import-Normal\">Primates are most distinguishable from other organisms in traits related to our vision. Our Order relies on vision as a primary sense, which is reflected in many areas of our anatomy and behaviour. All primates have eyes that face forward with convergent (overlapping) visual fields. So if you cover one eye with your hand, you can still see most of the room with your other one. This also means that we cannot see on the sides or behind us as well as some other animals can. In order to protect the sides of the eyes from the muscles we use for chewing, all primates have at least a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1132\">postorbital bar<\/a>, <\/strong>a bony ring around the outside of the eye (Figure 6.2). Primate taxa with more convergent eyes need extra protection, so animals with greater orbital convergence will have a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1134\">postorbital plate<\/a> <\/strong>or<strong> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1136\">postorbital closure<\/a> <\/strong>in addition to the bar (Figure 6.2).The postorbital bar is a derived trait of primates, appearing in our earliest ancestors.<\/p>\n<figure style=\"width: 661px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image2-4.jpg\" alt=\"Skulls of a monkey and lemur viewed from the side and top.\" width=\"661\" height=\"430\" \/><figcaption class=\"wp-caption-text\">Figure 6.2: All primates have bony protection around their eyes. Some have a postorbital bar only (right), but many have full postorbital closure, also called a postorbital plate, that completely protects the back of the eye socket (left). Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\" target=\"_blank\">Postorbital bar\/Postorbital closure (Figure 5.1)<\/a> a derivative work original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\" target=\"_blank\">CC BY-NC-SA 4.0 License<\/a>. [Includes <a href=\"https:\/\/animaldiversity.org\/accounts\/Otolemur_crassicaudatus\/specimens\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Otolemur_crassicaudatus\/lateral\/\" target=\"_blank\">Otolemur crassicaudatus (greater galago)<\/a> by <a href=\"https:\/\/animaldiversity.org\/\" target=\"_blank\">Animal Diversity Web<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\" target=\"_blank\">CC BY-NC-SA 3.0<\/a>; <a href=\"https:\/\/animaldiversity.org\/accounts\/Otolemur_crassicaudatus\/specimens\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Otolemur_crassicaudatus\/dorsal1809\/\" target=\"_blank\">Macaca fascicularis (long-tailed macaque)<\/a> by <a href=\"https:\/\/animaldiversity.org\/\" target=\"_blank\">Animal Diversity Web<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\" target=\"_blank\">CC BY-NC-SA 3.0<\/a>.]<\/figcaption><\/figure>\n<p class=\"import-Normal\">Another distinctive trait of our Order is that many primates have <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1140\">trichromatic color vision<\/a><\/strong>, the ability to distinguish reds and yellows in addition to blues and greens. Birds, fish, and reptiles are <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1142\">tetrachromatic<\/a> <\/strong>(they can see reds, yellows, blues, greens, and even ultraviolet), but most mammals, including some primates, are only <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1144\">dichromatic<\/a> <\/strong>(they see only in blues and greens). It is thought that the nocturnal ancestors of mammals benefited from seeing better at night rather than in colour, and so dichromacy is the ancestral condition for mammals. Trichromatic primates are known to use their colour vision for all sorts of purposes: finding young leaves and ripe fruits, identifying other species, and evaluating signals of health and fertility.<\/p>\n<p class=\"import-Normal\">The primate visual system uses a lot of energy, so primates have compensated by cutting back on other sensory systems, particularly our sense of smell. Compared to other mammals, primates have reduced snouts, another derived trait that appears even in the earliest primate ancestors. There is variation across primate taxa in how much snouts are reduced. Those with a better sense of smell usually have poorer vision than those with a relatively dull sense of smell. The reason for this is that all organisms have a limited amount of energy to spend on running our bodies, so we make <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1146\">evolutionary trade-offs<\/a><\/strong>, as energy spent on one trait cuts back on energy spent on another. So primates with better vision are spending more energy on vision and thus have a poorer smell (and shorter snout), and those who spend less energy on vision will have a better sense of smell (and a longer snout).<\/p>\n<p class=\"import-Normal\">Primates also differ from other mammals in the size and complexity of our brains. On average, primates have brains that are twice as big for their body size when compared to other mammals. Not unexpectedly, the visual centres of the brain are larger in primates and the wiring is different from that in other animals, reflecting our reliance on this sense. The neocortex, which is used for higher functions like consciousness and language in humans, as well as sensory perception and spatial awareness, is also larger in primates relative to other animals. In nonprimates this part of the brain is often smooth, but in primates it is made up of many folds, which increase the surface area. It has been proposed that the more complex neocortex of primates is related to diet, with fruit-eating primates having larger relative brain sizes than leaf-eating primates, due to the more challenging cognitive demands required to find and process fruits (Clutton-Brock &amp; Harvey 1980). An alternative hypothesis argues that larger brain size is necessary for navigating the complexities of primate social life, with larger brains occurring in species who live in bigger, more complex groups relative to those living in pairs or solitarily (Dunbar 1998). There seems to be support for both hypotheses, as large brains are a benefit under both sets of selective pressures.<\/p>\n<p class=\"import-Normal\">Animals with large brains usually have extended life history patterns, and primates are no exception. <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1148\">Life history<\/a> <\/strong>refers to the pace at which an organism grows, reproduces, and ages. Some animals grow very quickly and reproduce many offspring in a short time frame but do not live very long. Other animals grow slowly, reproduce few offspring, reproduce infrequently, and live a long time. Primates are all in the \u201cslow lane\u201d of life history patterns. Compared to animals of similar body size, primates grow and develop more slowly, have fewer offspring per pregnancy, reproduce less often, and live longer. Primates also invest heavily in each offspring. With a few exceptions, most primates only have one offspring at a time. A group of small-bodied monkeys in South America regularly give birth to twins, and some lemurs can give birth to multiple offspring at a time, but these primates are the exception rather than the rule. Primates also reproduce relatively infrequently. The fastest-reproducing primates will produce offspring about every six months, while the slowest, the orangutan, reproduces only once every seven to nine years. This very slow reproductive rate makes the orangutan the slowest-reproducing animal on the planet! Primates are also characterized by having long lifespans. The group that includes humans and large-bodied apes has the most extended life history patterns among all primates, with some large-bodied apes estimated to live up to 58 years in the wild (Robson Et al. 2006).<\/p>\n<figure style=\"width: 392px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image3-5.jpg\" alt=\"Various hands and feet of different primate species.\" width=\"392\" height=\"624\" \/><figcaption class=\"wp-caption-text\">Figure 6.3: These drawings of the hands and feet of different primates show the opposable thumbs and big toes, pentadactyly, flattened nails, and tactile pads characteristic of our Order. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:PrimateFeet.jpg\" target=\"_blank\">PrimateFeet<\/a> by <a href=\"https:\/\/en.wikipedia.org\/wiki\/Richard_Lydekker\" target=\"_blank\">Richard Lydekker<\/a>, original from The Royal Natural History 1:15 (1893), is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\" target=\"_blank\">public domain<\/a>.<\/figcaption><\/figure>\n<p>Primates also differ from other animals in our hands and feet. The Order Primates is a largely <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1150\">arboreal<\/a><\/strong> taxonomic group, meaning that most primates spend a significant amount of their time in trees. As a result, the hands and feet of primates have evolved to move in a three-dimensional environment. Primates have the generalized trait of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1152\">pentadactyly<\/a><\/strong>\u2014 possessing five digits (fingers and toes) on each limb. Many nonprimates, like dogs and horses, have fewer digits because they are specialized for high-speed, <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1154\">terrestrial<\/a><\/strong> (on the ground) running. Pentadactyly is also an ancestral trait, one that dates back to the earliest four-footed animals. Primates today have opposable thumbs and, with the exception of humans, opposable big toes (Figure 6.3). Opposable thumbs and toes are a derived trait that appeared in the earliest primate fossils about 55 million years ago. Having thumbs and big toes that go in a different direction from the rest of the fingers and toes allow primates to be excellent climbers in trees as well as to manipulate objects. Our ability to manipulate objects is further enhanced by the flattened nails on the backs of our fingers and toes that we possess in the place of the claws and hooves that many other mammals have. On the other side of our digits, we have sensitive <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1156\">tactile pads<\/a> <\/strong>that allow us to have a fine sense of touch. Primates use this fine sense of touch for handling food and, in many species, grooming themselves and others. In primates, grooming is an important social currency, through which individuals forge and maintain social bonds.<\/p>\n<table class=\"alignright\" style=\"width: 219.75pt;height: 407px\">\n<caption>Figure 6.4: Primate Traits at a Glance: This table summarizes the suite of traits that differentiate primates from other mammals. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\" target=\"_blank\">Primate at a glance table (Figure 5.3)<\/a> by Stephanie Etting original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/caption>\n<thead>\n<tr style=\"height: 30px\">\n<td class=\"a-C\" style=\"background-color: transparent;padding: 5pt;border: 1pt solid #000000;height: 30px;width: 361.667px\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Primate suite of traits<\/strong><\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"a-R\" style=\"height: 362px\">\n<td class=\"a-C\" style=\"background-color: transparent;padding: 5pt;border: 1pt solid #000000;height: 362px;width: 361.667px\">\n<p class=\"import-Normal\" style=\"text-align: center\">Convergent eyes<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Postorbital bar<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Many have trichromatic colour vision<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Short snouts<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Opposable thumbs and big toes<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Pentadactyly<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Flattened nails<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Tactile pads<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Highly arboreal<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Large brains<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Extended life histories<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Live in the tropics<\/p>\n<\/td>\n<\/tr>\n<tr style=\"height: 15px\">\n<td style=\"height: 15px;width: 362.033px\"><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>Lastly, primates are very social animals. All primates, even those that search for food alone, establish strong social networks within species. Unlike many animals, primates do not migrate: they stay in a relatively stable area for their whole life, often interacting with the same individuals for their long lives. The long-term relationships that primates form with others of their species lead to complex and fascinating social behaviours (see Chapter 7). Finally, nonhuman primates show a clear preference for tropical regions of the world. Most primates are found between the Tropic of Cancer and the Tropic of Capricorn, with only a few taxa living outside these regions. Figure 6.4 shows a summary of primate traits.<\/p>\n<h2 class=\"import-Normal\">Key Traits Used to Distinguish Between Primate Taxa<\/h2>\n<p class=\"import-Normal\">When placing primate species into specific taxonomic groups, we focus on dental characteristics, behavioural adaptations, and locomotor adaptations. Differences in these characteristics across groups reflect constraints of evolutionary history as well as variation in adaptations.<\/p>\n<h3 class=\"import-Normal\"><strong>Dental Characteristics<\/strong><\/h3>\n<p class=\"import-Normal\">Teeth may not seem like the most exciting topic with which to start, but we can learn a tremendous amount about an organism from its teeth. First, teeth are vital to survival. Wild animals do not have the benefit of knives and forks; they rely on their teeth to process their food. Because of this, teeth of any species have evolved to reflect what that organism eats and therefore have a lot to tell us about their diet. Second, variation in tooth size, shape, and number reveals an organism\u2019s evolutionary history. Some taxa have more teeth than others or different forms of teeth. Furthermore, differences in teeth between males and females can tell us about competition over mates (see Chapter 7). Lastly, teeth are overly represented in the fossil record. Enamel is hard, and there is little meat on jaws so carnivores and scavengers often leave them behind. Sometimes, the only remains we have from an extinct taxon is its teeth!<\/p>\n<figure style=\"width: 356px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image4-4-1.jpg\" alt=\"Yawning baboon with large teeth.\" width=\"356\" height=\"266\" \/><figcaption class=\"wp-caption-text\">Figure 6.5: This picture of an open-mouthed Hamadryas baboon demonstrates the diastema between his upper canine and front teeth. This space is taken up by his lower canine when he closes his mouth. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Ha,ha,ha_...._(14986571843).jpg\" target=\"_blank\">Ha,ha,ha .... (14986571843)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/104249543@N07\" target=\"_blank\">Rolf Dietrich Brecher<\/a> from Germany is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\" target=\"_blank\">CC BY-SA 2.0 License<\/a>.<\/figcaption><\/figure>\n<p>Like other mammals, primates are <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1158\">heterodont<\/a><\/strong>: they have multiple types of teeth that are used for different purposes. We have <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1160\">incisors<\/a> <\/strong>for slicing; <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1162\">premolars<\/a> <\/strong>and <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1164\">molars<\/a> <\/strong>for grinding up our food; and <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1166\">canines<\/a><\/strong>, which most primates (not humans) use as weapons against predators and each other. The sizes of canines vary across species and can often be <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1168\">sexually dimorphic<\/a><\/strong>, with males tending to have larger canines than females. Some nonhuman primates <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1170\">hone<\/a><\/strong>, or sharpen, their canines by gnashing the teeth together to sharpen the sides. The upper canine sharpens on the first lower premolar and the lower canine sharpens on the front of the upper canine. As canines get larger, they require a space to fit in order for the jaws to close. This space between the teeth is called a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1172\">diastema<\/a><\/strong> (Figure 6.5).<\/p>\n<p class=\"import-Normal\">We use a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1174\">dental formula<\/a><\/strong> to specify how many incisors, canines, premolars, and molars are in each quadrant of the mouth (half of the top or bottom). For example, Figure 6.6 shows half of the lower teeth of a human. You can see that in half of the mandible, there are two incisors, one canine, two premolars, and three molars. This dental formula is written as 2:1:2:3. (The first number represents the number of incisors, followed by the number of canines, premolars, and molars.)<\/p>\n<figure style=\"width: 241px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image5-5.png\" alt=\"Human mandible with four types of teeth.\" width=\"241\" height=\"424\" \/><figcaption class=\"wp-caption-text\">Figure 6.6:\u00a0 This drawing shows half of the human mandible. With the four types of teeth labeled, you can determine that the dental formula is 2:1:2:3. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Gray997.png\" target=\"_blank\">Gray997<\/a> by <a href=\"https:\/\/en.wikipedia.org\/wiki\/Henry_Vandyke_Carter\" target=\"_blank\">Henry Vandyke Carter<\/a>, original in Henry Gray (1918) Anatomy of the Human Body, Plate 997, is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\" target=\"_blank\">public domain<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">To determine the dental formula, you need to be able to identify the different types of teeth. You can recognize incisors because they often look like spatulas with a flat, blade-like surface. Premolars and molars can be differentiated by the number of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1176\">cusps<\/a><\/strong> that they have. Cusps are the bumps that you can feel with your tongue on the surface of your back teeth. Premolars are smaller than molars and, in primates, often have one or two cusps on them. Molars are bigger, providing a larger chewing surface, and have more cusps. Depending on the species and whether you\u2019re looking at upper or lower teeth, primate molars can have between three and five cusps. Molar cusps can also vary between taxa in how they are arranged; you will learn more about this later in this chapter. Canines are often easy to distinguish because, in most taxa, they are much longer and more conical than the other teeth.<\/p>\n<p class=\"import-Normal\">Teeth also directly reflect an organism\u2019s diet. Primates are known to eat a wide range of plant parts, insects, gums, and, rarely, meat. While all primates eat a variety of foods, what differs among primates are the proportions of each of these food items in the diet. That is, two primates living in the same forest may be eating the same foods but in vastly different proportions, and so we would categorize them as different dietary types. The most common dietary types among primates are those whose diets consist primarily of fruit (<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_954\">frugivores<\/a><\/strong>), those who eat mostly insects (<strong>insectivores<\/strong>), and those who eat primarily leaves (<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_956\">folivores<\/a><\/strong>). A few primate taxa are <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1178\">gummivores<\/a><\/strong>, specializing in eating gums and saps, but we will only focus on the adaptations found in the three primary dietary groups.<\/p>\n<h4 class=\"import-Normal\"><em>Frugivores<\/em><\/h4>\n<p class=\"import-Normal\">Plants want animals to eat their fruits because, in doing so, animals eat the seeds of the fruit and then disperse them far away from the parent plant. Therefore, plants often \u201cadvertise\u201d fruits by making them colourful and easy to spot, full of easy-to-digest sugars that make them taste good and, often, easy to chew and digest (not being too fibrous or tough). For these reasons, frugivores often do not need a lot of specialized traits to consume a diet rich in fruits (Figure 6.7). Their molars usually have a broad chewing surface with low, rounded cusps (referred to as <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1180\">bunodont<\/a> <\/strong>molars). Frugivores have large incisors for slicing through the outer coatings on fruit, and they tend to have stomachs, colons, and small intestines that are intermediate in terms of size and complexity between insectivores and folivores (Chivers &amp; Hladik 1980). They are also usually of intermediate body size between the other two dietary types. Because fruit does not contain protein, frugivores must supplement their diet with protein from insects, leaves, and\/or seeds. Frugivores who get protein by eating seeds evolved to have thicker enamel on their teeth to protect them from excessive wear.<\/p>\n<figure style=\"width: 503px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image6-2.jpg\" alt=\"Upper teeth and maxilla of a frugivore monkey.\" width=\"503\" height=\"331\" \/><figcaption class=\"wp-caption-text\">Figure 6.7: Frugivores are characterized by large incisors, bunodont molars, and digestive tracts that are intermediate in complexity between the other two dietary types. Credit: <a href=\"https:\/\/animaldiversity.org\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Papio_papio\/utr0087\/\" target=\"_blank\">Papio papio (Guinea baboon).jpg<\/a> by Phil Myers on <a href=\"https:\/\/animaldiversity.org\" target=\"_blank\">Animal Diversity Web<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\" target=\"_blank\">CC BY-NC-SA 3.0 License. <\/a><\/figcaption><\/figure>\n<h4 class=\"import-Normal\"><em>Insectivores<\/em><\/h4>\n<p class=\"import-Normal\">While insects can be difficult to find and catch, they are easy to chew and digest. As a result, insectivorous primates usually have small molars with pointed cusps to puncture the exoskeleton of the insects (Figure 6.8), and they have simple stomachs and colons with a long small intestine to process the insects. Nutritionally, insects provide a lot of protein and fat but are not plentiful enough in the environment to support large-bodied animals, so insectivores are usually the smallest of the primates.<\/p>\n<figure style=\"width: 351px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image7-3.jpg\" alt=\"Mandible, upper teeth, and maxilla of insectivore tarsier.\" width=\"351\" height=\"280\" \/><figcaption class=\"wp-caption-text\">Figure 6.8: Insectivores need sharp, pointed molar cusps to break through the exoskeletons of insects. Insects are easy to digest, so these primates have simple digestive tracts. Credit: Tarsier (an insectivor)\u2019s teeth original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Stephanie Etting is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\" target=\"_blank\">CC BY-NC-SA 3.0 License.<\/a> [Includes <a href=\"https:\/\/animaldiversity.org\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Tarsius_syrichta\/lower_lateral1942\/\" target=\"_blank\">Lower_lateral1942<\/a> by Phil Myers on <a href=\"https:\/\/animaldiversity.org\" target=\"_blank\">Animal Diversity Web<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\" target=\"_blank\">CC BY-NC-SA 3.0<\/a>; <a href=\"https:\/\/animaldiversity.org\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Tarsius_syrichta\/ventral\/\" target=\"_blank\">Ventral<\/a> by Phil Myers on <a href=\"https:\/\/animaldiversity.org\" target=\"_blank\">Animal Diversity Web<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\" target=\"_blank\">CC BY-NC-SA 3.0<\/a>.]<\/figcaption><\/figure>\n<h4 class=\"import-Normal\"><em>Folivores<\/em><\/h4>\n<p class=\"import-Normal\">Plants rely on leaves to get energy from the sun, so plants do not want animals to eat their leaves (unlike their fruit). As a result, plants evolved to try to discourage animals from eating their leaves. Leaves often carry toxins, taste bitter, are very fibrous and difficult to chew, and are made of large cellulose molecules that are difficult to break down into usable sugars. Thus, animals who eat leaves need a lot of specialized traits (Figure 6.9). Folivorous primates have broad molars with high, sharp cusps connected by <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1182\">shearing crests<\/a><\/strong>. These molar traits allow folivores to physically break down fibrous leaves when chewing. Folivores then chemically break down cellulose molecules into usable energy. To do this, some folivores have complex stomachs with multiple compartments, while others have large, long intestines and special gut bacteria that can break up cellulose. Folivores are usually the largest bodied of all primates, and they tend to spend a large portion of their day digesting their food, so they are less active than frugivores or insectivores.<\/p>\n<figure style=\"width: 468px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image8-2.jpg\" alt=\"Upper teeth and maxilla of a monkey shows folivore traits.\" width=\"468\" height=\"337\" \/><figcaption class=\"wp-caption-text\">Figure 6.9: To derive energy from leaves, folivores, like this Trachypithecus (dusky leaf monkey), have smaller incisors and high sharp molar cusps connected by shearing crests. Credit: <a href=\"https:\/\/animaldiversity.org\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Trachypithecus_obscurus\/utr0075\/\" target=\"_blank\">Trachypithecus obscurus (dusky leaf monkey) upper teeth<\/a> by Phil Myers on <a href=\"https:\/\/animaldiversity.org\" target=\"_blank\">Animal Diversity Web<\/a> has been modified (background removed, labels added by Stephanie Etting) is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\" target=\"_blank\">CC BY-NC-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<h3 class=\"import-Normal\"><strong>Behavioural Adaptations<\/strong><\/h3>\n<p class=\"import-Normal\">Since Chapter 6 is dedicated to primate behaviour, we will only briefly discuss variations in activity patterns, social grouping, and habitat use. Primate groups differ in <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1184\">activity patterns<\/a><\/strong>: whether they are active during the day (<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1012\">diurnal<\/a><\/strong>), at night (<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1010\">nocturnal<\/a><\/strong>), or through the 24-hour period (<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1186\">cathemeral<\/a><\/strong>). Primate taxa vary in social groupings: some are primarily solitary, others live in pairs, and still others live in groups of varying sizes and compositions. Lastly, some taxa are primarily arboreal while others are more terrestrial.<\/p>\n<h3 class=\"import-Normal\"><strong>Locomotor Adaptations<\/strong><\/h3>\n<p class=\"import-Normal\">Finally, primate groups vary in their adaptations for different forms of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1188\">locomotion<\/a><\/strong>, or how they move around. Living primates are known to move by vertical clinging and leaping, quadrupedalism, brachiation, and bipedalism.<\/p>\n<p class=\"import-Normal\"><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1190\">Vertical clinging and leaping<\/a> <\/strong>is when an animal grasps a vertical branch with its body upright, pushes off with long hind legs, and then lands on another vertical support branch (Figure 6.10a). Animals who move in this way usually have longer legs than arms, long fingers and toes, and smaller bodies. Vertical clinger leapers also tend to have elongated ankle bones, which serve as a lever to help them push off with their legs and leap to another branch (Figure 6.10b).<\/p>\n<figure id=\"attachment_181-16\" aria-describedby=\"caption-attachment-181-16\" style=\"width: 608px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-147\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/5.10.jpg\" alt=\"Movement of vertical clinger and leaper, and tarsier skeleton.\" width=\"608\" height=\"462\" \/><figcaption id=\"caption-attachment-181-16\" class=\"wp-caption-text\">Figure 6.10a: Vertical clingers and leapers have longer legs than arms, long lower backs, and long fingers and toes. They also have elongated ankle bones to help them push off when leaping. Credit: a. <a href=\"https:\/\/upload.wikimedia.org\/wikipedia\/commons\/6\/6e\/Propithecus_vertical_clinging_and_leaping.svg\" target=\"_blank\">Propithecus vertical clinging and leaping<\/a> by Terpsichores is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/\" target=\"_blank\"> CC BY-SA 3.0 License<\/a>. 6.10b: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Em_-_Tarsius_tarsier_-_3.jpg\" target=\"_blank\">Tarsier skeleton<\/a> by Em\u0151ke D\u00e9nes has been modified (background removed) by Stephanie Etting and is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/\" target=\"_blank\">CC BY-SA 4.0 License<\/a>. Original Spectral tarsier (Tarsius tarsier) skeleton at the Cambridge University Museum of Zoology, England.)<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<div class=\"learning-objectives\">\n<p class=\"import-Normal\"><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1192\">Quadrupedalism<\/a><\/strong>, walking on all fours, is the most common form of locomotion among primates. Quadrupedal animals usually have legs and arms that are about the same length and a tail for balance. Arboreal quadrupeds (Figure 6.11a) usually have shorter arms and legs and longer tails, while terrestrial quadrupeds (Figure 6.11b) have longer arms and legs and, often, shorter tails. These differences relate to the lower centre of gravity needed by arboreal quadrupeds for balance in trees and the longer tail required for better balance when moving along the tops of branches. Terrestrial quadrupeds have longer limbs to help them cover more distance more efficiently.<\/p>\n<\/div>\n<figure id=\"attachment_181-17\" aria-describedby=\"caption-attachment-181-17\" style=\"width: 704px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-148\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/5.11.jpg\" alt=\"Arboreal quadrupedal monkey and terrestrial quadrupedal monkey.\" width=\"704\" height=\"251\" \/><figcaption id=\"caption-attachment-181-17\" class=\"wp-caption-text\">Figure 6.11a\/b: Two examples of quadrupedal primates. The capuchin monkey skeleton on the left (a) is a typical arboreal quadruped with shorter arms and legs, longer fingers and toes, and a long tail. The baboon skeleton on the right (b) is a terrestrial quadruped with relatively long arms and legs, shorter fingers and toes, and a short tail. Credits: 6.11a. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Description_iconographique_compar%C3%A9e_du_squelette_et_du_syst%C3%A8me_dentaire_des_mammif%C3%A8res_r%C3%A9cents_et_fossiles_(Sapajus_apella).jpg\" target=\"_blank\">Capuchin monkey skeleton<\/a> by Henri-Marie Ducrotay de Blainville is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\" target=\"_blank\">public domain<\/a>. 6.11b. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Description_iconographique_compar%C3%A9e_du_squelette_et_du_syst%C3%A8me_dentaire_des_mammif%C3%A8res_r%C3%A9cents_et_fossiles_(Papio_ursinus).jpg\" target=\"_blank\">Baboon<\/a> by Henri-Marie Ducrotay de Blainville is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\" target=\"_blank\">public domain<\/a>.<\/figcaption><\/figure>\n<div class=\"learning-objectives\">\n<p class=\"import-Normal\">The third form of locomotion seen in primates is<strong> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1194\">brachiation<\/a><\/strong>, the way of moving you used if you played on \u201cmonkey bars\u201d as a child. Brachiation involves swinging below branches by the hands (Figure 6.12a). To be an efficient brachiator, a primate needs to have longer arms than legs, flexible shoulders and wrists, a short lower back, and no tail (Figure 6.12b). Some primates move via <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1196\">semi-brachiation<\/a><\/strong>, in which they swing below branches but do not have all of the same specializations as brachiators. Semi-brachiators have flexible shoulders, but their arms and legs are about the same length, which is useful because they are quadrupedal when on the ground. They also use long <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1198\">prehensile tails<\/a><\/strong> as a third limb when swinging (Figure 6.13). The underside of the tail has a tactile pad, resembling your fingerprints, for better grip.<\/p>\n<\/div>\n<figure id=\"attachment_181-18\" aria-describedby=\"caption-attachment-181-18\" style=\"width: 1600px\" class=\"wp-caption alignnone\"><img class=\"wp-image-149 size-full\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/5.12.jpg\" alt=\"Primate swinging through branches and gibbon skeleton.\" width=\"1600\" height=\"800\" \/><figcaption id=\"caption-attachment-181-18\" class=\"wp-caption-text\">Figure 6.12a. Example of brachiation. 6.12b. Skeleton of a typical brachiator, showing longer arms than legs, short back, and lack of a tail. Credit: a. <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\" target=\"_blank\">Brachiator (Figure 5.9b)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>. b. <a href=\"https:\/\/upload.wikimedia.org\/wikipedia\/commons\/a\/a3\/Giboia.jpg\" target=\"_blank\">Skeleton of Gibbon (Giboia) <\/a>by Joxerra Aihartza is under a <a href=\"https:\/\/artlibre.org\" target=\"_blank\">Free Art License<\/a>.<\/figcaption><\/figure>\n<div class=\"learning-objectives\">\n<figure style=\"width: 565px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image15-1.jpg\" alt=\"Spider monkey swinging below a rope.\" width=\"565\" height=\"377\" \/><figcaption class=\"wp-caption-text\">Figure 6.13. Spider monkeys are considered semi-brachiators, as they can swing below branches but use their tails as a third limb. On the ground they move via quadrupedal locomotion. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Ateles-fusciceps_54724770b.jpg\" target=\"_blank\">Ateles-fusciceps 54724770b<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:LeaMaimone\" target=\"_blank\">LeaMaimone<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.5\/legalcode\" target=\"_blank\">CC BY 2.5 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Lastly, humans move around on two feet, called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1200\">bipedalism<\/a><\/strong>. Some nonhuman primates will occasionally travel on two feet but do so awkwardly and never for long distances. Among mammals, only humans have evolved to walk with a striding gait on two legs as a primary form of locomotion.<\/p>\n<h2 class=\"import-Normal\">Primate Diversity<\/h2>\n<p class=\"import-Normal\">As we begin exploring the different taxa of primates, it is important to keep in mind the hierarchical nature of taxonomic classification and how this relates to the key characteristics that will be covered. Figure 6.14 summarizes the major taxonomic groups of primates that you will learn about here. If you locate humans on the chart, you can trace our classification and see all of the categories getting more inclusive as you work your way up to the Order Primates. This means that humans will have the key traits of each of those groups. It is a good idea to refer to the figure to orient yourself as we discuss each taxon.<\/p>\n<figure style=\"width: 2048px\" class=\"wp-caption alignnone\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image16-1.jpg\" alt=\"Taxonomic chart shows primate order, suborder, infraorder, superfamily, and species.\" width=\"2048\" height=\"1154\" \/><figcaption class=\"wp-caption-text\">Figure 6.14: This taxonomy chart shows the major groups of primate taxa, starting with the largest category (Order) and moving to more specific categories and examples. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\">A full text description of this image is available<\/a>. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\" target=\"_blank\">Primate taxonomy char (Figure 5.11)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>. [Includes <a href=\"https:\/\/phylopic.org\/image\/d6cfb28f-136e-4a20-a5ac-8eb353c7fc4a\/\" target=\"_blank\">Lemur catta Linnaeus, 1759<\/a> by Roberto D\u00edaz Sibaja, <a href=\"https:\/\/creativecommons.org\/licenses\/by\/3.0\/\" target=\"_blank\">CC BY 3.0<\/a>; <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\" target=\"_blank\">Lorisoidea<\/a> original to<a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\"> Explorations: An Open Invitation to Biological Anthropology<\/a> by Katie Nelson, <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0<\/a>; <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\" target=\"_blank\">Tarsiiformes<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson, <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0<\/a>; <a href=\"https:\/\/phylopic.org\/image\/156b515d-f25c-4497-b15b-5afb832cc70c\/\" target=\"_blank\">Cebinae Bonaparte, 1831<\/a> by Sarah Werning, <a href=\"https:\/\/creativecommons.org\/licenses\/by\/3.0\/\" target=\"_blank\">CC BY 3.0<\/a>; <a href=\"https:\/\/phylopic.org\/image\/899742c2-9a40-4fa0-b2cd-2eb133c8f6e8\/\" target=\"_blank\">Colobus guereza Ruppell, 1835<\/a> by Yan Wong, designated to the <a href=\"https:\/\/creativecommons.org\/publicdomain\/zero\/1.0\/\" target=\"_blank\">public domain (CC0)<\/a>; <a href=\"https:\/\/phylopic.org\/image\/72f2f854-f3cd-4666-887c-35d5c256ab0f\/\" target=\"_blank\">Papio cynocephalus<\/a> by Owen Jones, designated to the <a href=\"https:\/\/creativecommons.org\/publicdomain\/zero\/1.0\/\" target=\"_blank\">public domain (CC0)<\/a>; <a href=\"https:\/\/pixabay.com\/vectors\/animals-silhouette-wolf-elephant-2755766\/\" target=\"_blank\">animals silhouette wolf elephant (2755766)<\/a> by <a href=\"https:\/\/pixabay.com\/users\/mohamed_hassan-5229782\/\" target=\"_blank\">mohamed_hassan<\/a>, <a href=\"https:\/\/pixabay.com\/service\/terms\/#license\" target=\"_blank\">Pixabay License<\/a>.]<\/figcaption><\/figure>\n<h3 class=\"import-Normal\"><strong>Suborder Strepsirrhini<\/strong><\/h3>\n<figure style=\"width: 387px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image17-1.jpg\" alt=\"Eight strepsirrhine species.\" width=\"387\" height=\"605\" \/><figcaption class=\"wp-caption-text\">Figure 6.15: (Clockwise from top right) sifaka, black-and-white ruffed lemur, loris, galago, slender loris, mouse lemur, aye-aye, and ring-tailed lemur. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Extant_Strepsirrhini.jpg\" target=\"_blank\">Extant Strepsirrhini<\/a> a collective work by <a href=\"https:\/\/www.flickr.com\/people\/23661161@N02\" target=\"_blank\">Mark Dumont<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0 License<\/a>. [Includes <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Katta_csal%C3%A1d.jpg\" target=\"_blank\">Katta csal\u00e1d<\/a> by Veszpr\u00e9mi \u00c1llatkert, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Aye-aye_at_night_in_the_wild_in_Madagascar.jpg\" target=\"_blank\">Aye-aye at night in the wild in Madagascar<\/a> by Frank Vassen, <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/deed.en\" target=\"_blank\">CC BY 2.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Diademed_ready_to_push_off.jpg\" target=\"_blank\">Diademed ready to push off<\/a> by Michael Hogan, designated to the <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/cc0\/\" target=\"_blank\">public domain (CC0)<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Juvenile_Black-and-White_Ruffed_Lemur,_Mantadia,_Madagascar.jpg\" target=\"_blank\">Juvenile Black-and-White Ruffed Lemur, Mantadia, Madagascar<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/42244964@N03\" target=\"_blank\">Frank Vassen<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/legalcode\" target=\"_blank\">CC BY 2.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Microcebus_murinus_-Artis_Zoo,_Amsterdam,_Netherlands-8a.jpg\" target=\"_blank\">Microcebus murinus -Artis Zoo, Amsterdam, Netherlands-8a<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/46956042@N00\" target=\"_blank\">Arjan Haverkamp<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/legalcode\" target=\"_blank\">CC BY 2.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Slow_Loris.jpg\" target=\"_blank\">Slow Loris<\/a> by Jmiksanek, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Slender_Loris.jpg\" target=\"_blank\">Slender Loris<\/a> by Kalyan Varma (<a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Kalyanvarma\" target=\"_blank\">Kalyanvarma<\/a>), <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\" target=\"_blank\">CC BY-SA 4.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Garnett&apos;s_Galago_(Greater_Bushbaby).jpg\" target=\"_blank\">Garnett's Galago (Greater Bushbaby)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/23661161@N02\" target=\"_blank\">Mark Dumont<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/legalcode\" target=\"_blank\">CC BY 2.0<\/a>.]<\/figcaption><\/figure>\n<p>The Order Primates is subdivided into Suborder Strepsirrhini and Suborder Haplorrhini, which, according to molecular estimates, split about 70\u201380 million years ago (Pozzi et al. 2014). The strepsirrhines include the groups commonly called lemurs, lorises, and galagos (Figure 6.15). Strepsirrhines differ from haplorrhines in many ways, most of which involve retaining ancestral traits from the earliest primates. Strepsirrhines do have two key derived traits that evolved after they diverged from the haplorrhines: the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1202\">grooming claw<\/a> <\/strong>(Figure 6.16) on the second digit of each foot, and the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1204\">tooth comb<\/a><\/strong> (or <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1206\">dental comb<\/a><\/strong>) located on the lower, front teeth (Figure 6.17). In most strepsirrhines, there are six teeth in the toothcomb\u2014four incisors and two canines. Other than the tooth comb, the teeth of strepsirrhines are fairly simple and are neither large or distinctive relative to haplorrhines.<\/p>\n<figure style=\"width: 237px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image18.jpg\" alt=\"A long, thin dark claw is visible in contrast to flat dark nails on the other digits.\" width=\"237\" height=\"202\" \/><figcaption class=\"wp-caption-text\">Figure 6.16: The foot of a ring-tailed lemur showing its grooming claw on the second digit. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Lemur_catta_toilet_claw.jpg\" target=\"_blank\">Lemur catta toilet claw<\/a> by Alex Dunkel (Maky) is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/3.0\/legalcode\" target=\"_blank\">CC BY 3.0 License.<\/a><\/figcaption><\/figure>\n<p class=\"import-Normal\">Compared to haplorrhines, strepsirrhines rely more on nonvisual senses. Strepsirrhines get their name because they have wet noses (<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1208\">rhinariums<\/a><\/strong>) like cats and dogs, a trait that, along with a longer snout, reflect strepsirrhines\u2019 greater reliance on olfaction relative to haplorrhines. Many strepsirrhines use <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1210\">scent marking<\/a><\/strong>, including rubbing scent glands or urine on objects in the environment to communicate with others. Additionally, many strepsirrhines have mobile ears that they use to locate insect prey and predators. While strepsirrhines have a better sense of smell than haplorrhines, their visual adaptations are more ancestral. Strepsirrhines have less convergent eyes than haplorrhines and therefore all have postorbital bars, whereas haplorrhines have full postorbital closure (see Figure 6.2). All strepsirrhines have a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1212\">tapetum lucidum<\/a><\/strong>, a reflective layer at the back of the eye that reflects light and thereby enhances the ability to see in low-light conditions. It is the same layer that causes your dog or cat to have \u201cyellow eye\u201d when you take photos of them with the flash on. This is a trait thought to be ancestral among mammals as a whole.<\/p>\n<figure style=\"width: 292px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image19-1.jpg\" alt=\"The lower, front teeth are long, thin, tightly together in a line, and project towards the lips.\" width=\"292\" height=\"354\" \/><figcaption class=\"wp-caption-text\">Figure 6.17: The lower front teeth of a ring-tailed lemur showing the six teeth of the tooth comb: four incisors and two canines. The teeth that superficially look like canines are premolars. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Lemur_catta_toothcomb.jpg\" target=\"_blank\">Lemur catta toothcomb<\/a> by Alex Dunkel (Maky) is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/3.0\/legalcode\" target=\"_blank\">CC BY 3.0 license.<\/a><\/figcaption><\/figure>\n<p class=\"import-Normal\">Strepsirrhines also differ from haplorrhines in some aspects of their ecology and behaviour. The majority of strepsirrhines are solitary, traveling alone to search for food; a few taxa are more social. Most strepsirrhines are also nocturnal and arboreal. Strepsirrhines are, on average, smaller than haplorrhines, and so many of them have a diet consisting of insects and fruit, with few taxa eating primarily leaves. Lastly, most strepsirrhines are good at leaping, with several taxa specialized for vertical clinging and leaping. In fact, among primates, all but one of the vertical clinger leapers belong to the Suborder Strepsirrhini.<\/p>\n<p class=\"import-Normal\">Strepsirrhines can be found all across Asia, Africa, and on the island of Madagascar (Figure 6.18). The Suborder Strepsirrhini is divided into two groups: (1) the lemurs of Madagascar and (2) the lorises, pottos, and galagos of Africa and Asia. By molecular estimates, these two groups split about 65 million years ago (Pozzi Et al. 2014).<\/p>\n<figure style=\"width: 443px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image20-1.png\" alt=\"Map strepsirrhine primates locations.\" width=\"443\" height=\"342\" \/><figcaption class=\"wp-caption-text\">Figure 6.18: Geographic distribution of living strepsirrhines. Lemurs live only on Madagascar, while lorises and galagos live across Central Africa and South and Southeast Asia. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\" target=\"_blank\">Geographic distribution of living strepsirrhines (Figure 5.16)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Elyssa Ebding at <a href=\"https:\/\/www.csuchico.edu\/geop\/geoplace\/index.shtml\" target=\"_blank\">GeoPlace, California State University, Chico<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<h4><em>Lemurs of Madagascar<\/em><\/h4>\n<p class=\"import-Normal\">Madagascar is an island off the east coast of Africa, and it is roughly the size of California, Oregon, and Washington combined. It has been separated from Africa for about 130 million years and from India for about 85 million years, which means it was already an island when strepsirrhines got there approximately 60\u201370 million years ago. Only a few mammal species ever reached Madagascar, and so when lemurs arrived they were able to flourish into a variety of forms.<\/p>\n<p class=\"import-Normal\">The lemurs of Madagascar are much more diverse compared to their mainland counterparts, the lorises and galagos. While many Malagasy strepsirrhines are nocturnal, plenty of others are diurnal or cathemeral. They range in body size from the smallest of all primates, the mouse lemur, some species of which weigh a little over an ounce (see Figure 6.15), up to the largest of all strepsirrhines, the indri, which weighs up to about 20 pounds (Figure 6.19). Lemurs include species that are insectivorous, frugivorous, and folivorous. A couple of members of this group have unusual diets for primates, including the gummivorous fork-marked and bamboo lemurs, who are able to metabolize the cyanide in bamboo. The most unique lemur is the aye-aye (depicted in Figure 6.15). This nocturnal lemur has rodent-like front teeth that grow continuously and a long-bony middle finger that it uses to fish grubs out of wood. It has a very large brain compared to other strepsirrhines, which it fuels with a diet that includes bird\u2019s eggs and other animal matter. Based on genetic estimates and morphological studies, it is believed that aye-ayes were the first lemurs to separate from all other strepsirrhines and to evolve on their own since strepsirrhines arrived in Madagascar (Matsui Et al. 2009).<\/p>\n<figure style=\"width: 326px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image21-1-1.jpg\" alt=\"Two Indis in a tree.\" width=\"326\" height=\"217\" \/><figcaption class=\"wp-caption-text\">Figure 6.19: Indris, the largest of the lemurs. These folivorous lemurs are vertical clingers and leapers and live in pairs. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Indri_indri_0003.jpg\" target=\"_blank\">Indri indri 0003<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Christophe_Germain\" target=\"_blank\">Christophe Germain<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\" target=\"_blank\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Lemurs are also diverse in terms of social behaviour: Many lemurs are solitary foragers, some live in pairs, others in small groups, still others in larger groups, and some, like the red-ruffed lemur, live in unique and complex social groups (Vasey 2006). Lemurs include some of the best vertical clingers and leapers, and while many lemurs are quadrupedal, even the quadrupedal lemurs are quite adept at leaping. Malagasy strepsirrhines also exhibit a few unusual traits. They are highly seasonal breeders, often mating only during a short window once a year (Wright 1999). Female ring-tailed lemurs, for example, come into estrus one day a year for a mere six hours. Unlike most primates, where males are typically large and dominant, Malagasy strepsirrhines feature socially dominant females that are similar in size to males and have priority access to resources.<\/p>\n<h4 class=\"import-Normal\"><em>Lorises, Pottos, and Galagos of Asia and Africa<\/em><\/h4>\n<figure style=\"width: 207px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image22-1.jpg\" alt=\"Slow loris hanging from a branch.\" width=\"207\" height=\"309\" \/><figcaption class=\"wp-caption-text\">Figure 6.20: This slow loris, like all others in this taxonomic group, is solitary and nocturnal, with a diet heavy in insects and fruit. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Nycticebus_coucang_002.jpg\" target=\"_blank\">Nycticebus coucang 002<\/a> by David Haring \/ Duke Lemur Center is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/deed.en\" target=\"_blank\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p>Unlike the lemurs of Madagascar, lorises, pottos, and galagos live in areas where they share their environments with monkeys and apes, who often eat similar foods. Lorises live across South and Southeast Asia, while pottos and galagos live across Central Africa. Because of competition with larger-bodied monkeys and apes, mainland strepsirrhines are more restricted in the niches they can fill in their environments and so are less diverse than the lemurs.<\/p>\n<p>The strepsirrhines of Africa and Asia are all nocturnal and solitary, with little variation in body size and diet. For the most part, the diet of lorises, pottos, and galagos consists of fruits and insects. A couple of species eat more gum, but overall the diet of this group is narrow when compared to the Malagasy lemurs. Lorises (Figure 6.20) and pottos are known for being slow, quadrupedal climbers, moving quietly through the forests to avoid being detected by predators. These strepsirrhines have developed additional defences against predators. Lorises, for example, eat a lot of caterpillars, which makes their saliva slightly toxic. Loris mothers bathe their young in this toxic saliva, making the babies unappealing to predators. In comparison to the slow-moving lorises and pottos, galagos are active quadrupedal runners and leapers that scurry about the forests at night. Galagos make distinctive calls that sound like a baby crying, which has led to their nickname \u201cbushbabies.\u201d Figure 6.21 summarizes the key differences between these two groups of strepsirrhines.<\/p>\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<caption>Figure 6.21: Strepsirrhini at a glance: This table summarizes the key differences between the two groups of strepsirrhines. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\" target=\"_blank\">Strepsirrhines at a glance table (Figure 5.19)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\" target=\"_blank\">CC BY-NC-SA 4.0 License<\/a>. [Includes <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Ringtailed_Lemurs_in_Berenty.jpg\" target=\"_blank\">Ringtailed Lemurs in Berenty<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/50852241@N00\" target=\"_blank\">David Dennis<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\" target=\"_blank\">CC BY-SA 2.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Komba_u%C5%A1at%C3%A1.jpg\" target=\"_blank\">Komba u\u0161at\u00e1<\/a> by Petr Hamern\u00edk, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\" target=\"_blank\">CC BY-SA 4.0<\/a>.]<\/caption>\n<thead>\n<tr>\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong><img class=\"alignnone\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image23-1.jpg\" alt=\"Baby primate on the back of adult primate.\" width=\"231\" height=\"165\" \/><\/strong><\/p>\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Lemurs<\/strong><\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong><img class=\"alignnone\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image24-1.jpg\" alt=\"Small primate with big eyes and long tail.\" width=\"198\" height=\"132\" \/><\/strong><\/p>\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Lorises, Pottos, and Galagos<\/strong><\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"a0-R\">\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Geographic range<\/strong><\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Madagascar<\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">South and Southeast Asia<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Central Africa<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a0-R\">\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Activity patterns<\/strong><\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Diurnal, nocturnal, or cathemeral<\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Nocturnal<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a0-R\">\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Dietary types<\/strong><\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Insectivore, frugivore, or folivore<\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Insectivore, frugivore<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a0-R\">\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Social groupings<\/strong><\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Solitary, pairs, or small to large groups<\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Solitary<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a0-R\">\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Forms of locomotion<\/strong><\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Vertical clinger leapers, quadrupedal<\/p>\n<\/td>\n<td class=\"a0-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Slow quadrupedal climbers and active quadrupedal runners<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h3 class=\"import-Normal\"><strong>Suborder Haplorrhini<\/strong><\/h3>\n<p class=\"import-Normal\">When the two primate suborders split from one another, strepsirrhines retained more ancestral traits while haplorrhines developed more derived traits, which are discussed below.<\/p>\n<p class=\"import-Normal\">As mentioned earlier, haplorrhines have better vision than strepsirrhines. This is demonstrated by the full postorbital closure protecting the more convergent eyes that haplorrhines possess (with one exception seen in Figure 6.2). Most haplorrhines are trichromatic, and all have a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1410\">fovea<\/a><\/strong>, a depression in the retina at the back of the eye containing concentrations of cells that allows them to see things very close up in great detail. The heavier reliance on vision over olfaction is also reflected in the shorter snouts ending with the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1412\">dry nose<\/a> <\/strong>(no rhinarium) of haplorrhines. All but two genera of living haplorrhines are active during the day, so this group lacks the tapetum lucidum that is so useful to nocturnal species. On average, haplorrhines also have larger brains relative to their body size when compared with strepsirrhines.<\/p>\n<p class=\"import-Normal\">The Haplorrhini differ from the Strepsirrhini in their ecology and behaviour as well. Haplorrhines are generally larger than strepsirrhines, and they tend to be folivorous and frugivorous. This dietary difference is reflected in the teeth of haplorrhines, which are broader with more surface area for chewing. The larger body size of this taxon also influences locomotion. Only one haplorrhine is a vertical clinger and leaper. Most members of this suborder are quadrupedal, with one subgroup specialized for brachiation. A few haplorrhine taxa are <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1414\">monomorphic<\/a><\/strong>, meaning males and females are the same size, but many members of this group show moderate to high sexual dimorphism in body size and canine size. Haplorrhines also differ in social behaviour. All but two haplorrhines live in groups, which is very different from the primarily solitary strepsirrhines. Differences between the two suborders are summarized in Figure 6.22.<\/p>\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<caption>Figure 6.22: Suborders at a glance: This table summarizes the key differences between the two primate suborders. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\" target=\"_blank\">Suborders at a glance table (Figure 5.20)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\" target=\"_blank\">CC BY-NC-SA 4.0 License<\/a>. [Includes <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Black-and-White_Ruffed_Lemur,_Mantadia,_Madagascar.jpg\" target=\"_blank\">Black-and-White Ruffed Lemur, Mantadia, Madagascar<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/42244964@N03\" target=\"_blank\">Frank Vassen<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/legalcode\" target=\"_blank\">CC BY 2.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Crab_eating_macaque_face.jpg\" target=\"_blank\">Crab eating macaque face<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Bruce89\" target=\"_blank\">Bruce89<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\" target=\"_blank\">CC BY-SA 4.0<\/a>.]<\/caption>\n<thead>\n<tr>\n<td class=\"a1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong><img class=\"alignnone\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image25.jpg\" alt=\"Black-and-white ruffed lemur.\" width=\"213\" height=\"159\" \/><\/strong><strong>Suborder Strepsirrhini<\/strong><\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong><img class=\"alignnone\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image26-1.jpg\" alt=\"Crab-eating macaque.\" width=\"137\" height=\"137\" \/><\/strong><\/p>\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Suborder Haplorrhini<\/strong><\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"a1-R\">\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Sensory adaptations<\/strong><\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Rhinarium<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Longer snout<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Eyes less convergent<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Postorbital bar<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Tapetum lucidum<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Mobile ears<\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">No rhinarium<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Short snout<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Eyes more convergent<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Postorbital plate<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">No tapetum lucidum<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Many are trichromatic<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Fovea<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a1-R\">\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Dietary differences<\/strong><\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Mostly insectivores and frugivores, few folivores<\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Few insectivores, mostly frugivores and folivores<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a1-R\">\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Activity patterns and Ecology<\/strong><\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Mostly nocturnal, few diurnal or cathemeral<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Almost entirely arboreal<\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Only two are nocturnal, rest are diurnal<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Many arboreal taxa, also many terrestrial taxa<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a1-R\">\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Social groupings<\/strong><\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Mostly solitary, some pairs, small to large groups<\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Only two are solitary, all others live in pairs, small to very large groups<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a1-R\">\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Sexual dimorphism<\/strong><\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Minimal to none<\/p>\n<\/td>\n<td class=\"a1-C\" style=\"background-color: transparent;vertical-align: middle;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Few taxa have little\/none, many taxa show moderate to high dimorphism<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p class=\"import-Normal\">Suborder Haplorrhini is divided into three infraorders: Tarsiiformes, which includes the tarsiers of Asia; Platyrrhini, which includes the monkeys of Central and South America; and Catarrhini, a group that includes the monkeys of Asia and Africa, apes, and humans. According to molecular estimates, tarsiers split from the other haplorrhines close to 70 million years ago, and platyrrhines split from catarrhines close to 46 million years ago (Pozzi Et al. 2014).<\/p>\n<h4 class=\"import-Normal\"><em>Infraorder Tarsiiformes of Asia<\/em><\/h4>\n<figure style=\"width: 188px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image27-1.jpg\" alt=\"Tarsier gripping a branch.\" width=\"188\" height=\"160\" \/><figcaption class=\"wp-caption-text\">Figure 6.23: Tarsiers are the only living representatives of this Infraorder. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Tarsier_Sanctuary,_Corella,_Bohol_(2052878890).jpg\" target=\"_blank\">Tarsier Sanctuary, Corella, Bohol (2052878890)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/46274125@N00\" target=\"_blank\">yeowatzup<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/legalcode\" target=\"_blank\">CC BY 2.0 License<\/a>.<\/figcaption><\/figure>\n<figure style=\"width: 362px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image28-1.png\" alt=\"Map of Southeast Asia shows distribution of tarsiers.\" width=\"362\" height=\"279\" \/><figcaption class=\"wp-caption-text\">Figure 6.24: Tarsiiformes are found in the tropical forests of multiple islands in Southeast Asia including Sumatra, Borneo, Celebes, and the Philippines. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\" target=\"_blank\">Infraorder Tarsiiformes of Asia map (Figure 5.22)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Elyssa Ebding at <a href=\"https:\/\/www.csuchico.edu\/geop\/geoplace\/index.shtml\" target=\"_blank\">GeoPlace, California State University, Chico<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p>Today, the Infraorder Tarsiiformes includes only one genus, <em>Tarsius <\/em>(Figure 6.23). Tarsiers are small-bodied primates that live in Southeast Asian forests (Figure 6.24) and possess an unusual collection of traits that have led to some debate about their position in the primate taxonomy. They are widely considered members of the haplorrhine group because they share several derived traits with monkeys, apes, and humans, including dry noses, a fovea, not having a tapetum lucidum, and eyes that are more convergent. Tarsiers also have some traits that are more like strepsirrhines and some that are unique. Tarsiers are the only haplorrhine that are specialized vertical clinger leapers, a form of locomotion only otherwise seen in some strepsirrhines. Tarsiers actually get their name because their ankle (tarsal) bones are elongated to provide a lever for vertical clinging and leaping. Tarsiiformes are also small, with most species weighing between 100 and 150 grams. Like strepsirrhines, tarsiers are nocturnal, but because they lack a tapetum lucidum, tarsiers compensate by having enormous eyes. In fact, each eye of a tarsier is larger than its brain. These large eyes allow enough light in for tarsiers to still be able to see well at night without the reflecting layer in their eyes. To protect their large eyes, tarsiers have a partially closed postorbital plate that appears somewhat intermediate between the postorbital bar of strepsirrhines and the full postorbital closure of other haplorrhines (Figure 6.25). Tarsiers have different dental formulas on their upper and lower teeth. On the top, the dental formula is 2:1:3:3, but on the bottom it is 1:1:3:3. Other unusual traits of tarsiers include having two grooming claws on each foot and the ability to rotate their heads around 180 degrees, a trait useful in locating insect prey. The tarsier diet is considered <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1416\">faunivorous<\/a> <\/strong>because it consists entirely of animal matter, making them the only primate not to eat any vegetation. They are only one of two living haplorrhines to be solitary, the other being the orangutan. Most tarsiers are not sexually dimorphic, like strepsirrhines, although males of a few species are slightly larger than females.<\/p>\n<figure style=\"width: 486px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image29-1.jpg\" alt=\"Front view of tarsier skull.\" width=\"486\" height=\"323\" \/><figcaption class=\"wp-caption-text\">Figure 6.25: Skull of a tarsier showing very large eye sockets and partially closed postorbital plates. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Tarsier_skull.jpg\" target=\"_blank\">Tarsier skull<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/65438265@N00\" target=\"_blank\">Andrew Bardwell<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\" target=\"_blank\">CC BY-SA 2.0 License.<\/a><\/figcaption><\/figure>\n<p class=\"import-Normal\">Two alternative classifications have emerged due to the unusual mix of traits that tarsiers have. Historically, tarsiers were grouped with lemurs, lorises, and galagos into a suborder called Prosimii. This classification was based on tarsiers, lemurs, lorises, and galagos all having grooming claws and similar lifestyles. Monkeys, apes, and humans were then separated into a suborder called the Anthropoidea. These suborder groupings were based on <em>grade<\/em> rather than <em>clade<\/em>. Today, most people use Suborders Strepsirrhini and Haplorrhini, which are clade groupings based on the derived traits that tarsiers share with monkeys, apes, and humans. The Strepsirrhini\/Haplorrhini dichotomy is also supported by the genetic evidence that indicates tarsiers are more closely related to monkeys, apes, and humans (Jameson Et al. 2011). Figure 6.26 summarizes the unusual mix of traits seen in tarsiers.<\/p>\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<caption>Figure 6.26: Tarsiers at a glance: Tarsiers have a mix of traits that lead to debate about their classification. While they have some unique characteristics, they also have traits that superficially resemble strepsirrhines, and many derived traits shared with haplorrhines. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\" target=\"_blank\">Tarsiers at a glance table (Figure 5.24)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/caption>\n<thead>\n<tr>\n<td class=\"a2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Like Strepsirrhini<\/strong><\/p>\n<\/td>\n<td class=\"a2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Unique<\/strong><\/p>\n<\/td>\n<td class=\"a2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Like Haplorrhini<\/strong><\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"a2-R\">\n<td class=\"a2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Very small<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Nocturnal<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Highly insectivorous<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Solitary<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Vertical clinger-leapers<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Little\/no sexual dimorphism<\/p>\n<\/td>\n<td class=\"a2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Two grooming claws<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">2:1:3:3\/1:1:3:3 dental formula<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Do not eat vegetation<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Can rotate their heads nearly 180 degrees<\/p>\n<\/td>\n<td class=\"a2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Almost full PO closure<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">More convergent eyes<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">No tapetum lucidum<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">No rhinarium<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Genetic evidence<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Fovea<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h4 class=\"import-Normal\"><em>Infraorder Platyrrhini of Central and South America<\/em><\/h4>\n<figure id=\"attachment_179-4\" aria-describedby=\"caption-attachment-179-4\" style=\"width: 329px\" class=\"wp-caption alignleft\"><img class=\"wp-image-165\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image30-e1686352290168.png\" alt=\"Map of South America shows where platyrrhines live.\" width=\"329\" height=\"324\" \/><figcaption id=\"caption-attachment-179-4\" class=\"wp-caption-text\">Figure 6.27: Geographic distribution of the platyrrhines across the southern part of Central America and the tropical and termporate regions of South America. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/ target=\">Infraorder Platyrrhini map<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Elyssa Ebding at <a href=\"https:\/\/www.csuchico.edu\/geop\/geoplace\/index.shtml\" target=\"_blank\">GeoPlace, California State University, Chico<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p>The platyrrhines are the only nonhuman primates in Central and South America (Figure 6.27) and so, like the lemurs of Madagascar, have diversified into a variety of forms in the absence of competition. Infraorder Platyrrhini get their name from their distinctive nose shape. \u201cPlaty\u201d means flat and \u201crhini\u201d refers to noses, and, indeed, platyrrhines have noses that are flat and wide, with nostrils that are far apart, facing outward, and usually round in shape (Figure 6.28). This nose shape is very different from what we see in catarrhines.<\/p>\n<p>On average, platyrrhines are smaller and less sexually dimorphic than catarrhines, and they have retained the more ancestral primate dental formula of 2:1:3:3. Platyrrhines are all highly arboreal, whereas many catarrhines spend significant time on the ground. The monkeys in Central and South America also differ in having less well-developed vision. This is reflected in the wiring in the visual system of the brain as well as in their <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1418\">polymorphic color vision<\/a><\/strong>. The genes that enable individuals to distinguish reds and yellows from blues and greens are on the X chromosome. Different genes code for being able to see different wavelengths of light so to distinguish between them you need to be heterozygous for seeing colour. The X chromosomes of platyrrhines each carry the genes for seeing one wavelength, so male platyrrhines (with only one X chromosome) are always dichromatic. Female platyrrhines can be dichromatic (if they are homozygous for one version of the colour vision gene) or trichromatic (if they are heterozygous) (Kawamura Et al. 2012). We currently know of two exceptions to this pattern among platyrrhines. Nocturnal owl monkeys are <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1420\">monochromatic<\/a><\/strong>, meaning that they cannot distinguish any colours. The other exception are howler monkeys, which have evolved to have two colour vision genes on each X chromosome. This means that both male and female howler monkeys are able to see reds and yellows. By contrast, catarrhine males and females are all trichromatic.<\/p>\n<figure style=\"width: 279px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image31-1.jpg\" alt=\"White-faced capuchin monkey.\" width=\"279\" height=\"190\" \/><figcaption class=\"wp-caption-text\">Figure 6.28: A capuchin monkey demonstrating a typical platyrrhine nose shape with round nostrils pointing outward on a flat nose. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:CARABLANCA_-_panoramio.jpg\" target=\"_blank\">CARABLANCA - panoramio<\/a> by Manuel Velazquez is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/3.0\/legalcode\" target=\"_blank\">CC BY 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Platyrrhines include the smallest of the monkeys, the marmosets and tamarins (Figure 6.29), all of which weigh less than one kilogram and live in cooperative family groups, wherein usually only one female reproduces and everyone else helps carry and raise the offspring. They are unusual primates in that they regularly produce twins. Marmosets and tamarins largely eat gums and saps, so these monkeys have evolved claw-like nails that enable them to cling to the sides of tree trunks like squirrels as well as special teeth that allow them to gnaw through bark. Except for the Goeldi\u2019s monkey, these small monkeys have one fewer molar than other platyrrhines, giving them a dental formula of 2:1:3:2.<\/p>\n<figure style=\"width: 428px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image32-1.jpg\" alt=\"Six marmoset and tamarin species.\" width=\"428\" height=\"470\" \/><figcaption class=\"wp-caption-text\">Figure 6.29: Clockwise from top right: golden-headed lion tamarin, pygmy marmoset, Goeldi\u2019s monkey, bare-eared marmoset, emperor tamarin, and common marmoset. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Callitrichinae_genus.jpg\" target=\"_blank\">Callitrichinae genus<\/a> by Miguelrangeljr is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/deed.en\" target=\"_blank\">CC BY-SA 3.0 License<\/a>. [Includes <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Wei%C3%9Fb%C3%BCschelaffe_(Callithrix_jacchus).jpg\" target=\"_blank\">Wei\u00dfb\u00fcschelaffe_(Callithrix_jacchus)<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Raymond\" target=\"_blank\">Raymond<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/\" target=\"_blank\">CC BY-SA 4.0<\/a>;\u00a0 <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Leontopithecus_chrysomelas_(portrait).jpg\" target=\"_blank\">Leontopithecus chrysomelas (portrait)<\/a> by Hans Hillewaert, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/\" target=\"_blank\">CC BY-SA 4.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Emperor_Tamarin_portrait_2_edit1.jpg\" target=\"_blank\">Emperor_Tamarin_portrait_2_edit1<\/a> by <a href=\"https:\/\/sites.google.com\/site\/thebrockeninglory\/\" target=\"_blank\">Brocken Inaglory<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/\" target=\"_blank\">CC BY-SA 4.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Dv%C3%A6rgsilkeabe_Callithrix_pygmaea.jpg\" target=\"_blank\">Dv\u00e6rgsilkeabe_Callithrix_pygmaea<\/a> by Malene Thyssen (User <a href=\"https:\/\/da.wikipedia.org\/wiki\/User:Malene\" target=\"_blank\">Malene<\/a>), <a href=\"https:\/\/en.wikipedia.org\/wiki\/GNU_Free_Documentation_License\" target=\"_blank\">GNU Free Documentation License<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Mico_argentatus_(portrait).jpg\" target=\"_blank\">Mico_argentatus_(portrait)<\/a> by Hans Hillewaert, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/\" target=\"_blank\">CC BY-SA 4.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Titi_Monkey.jpg\" target=\"_blank\">Titi Monkey<\/a> by Jeff Kubina, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/deed.en\" target=\"_blank\">CC BY-SA 2.0<\/a>].]<\/figcaption><\/figure>\n<p class=\"import-Normal\">The largest platyrrhines are a family that include spider monkeys, woolly spider monkeys, woolly monkeys, and howler monkeys (Figure 6.30). These monkeys can weigh up to 9\u201315 kg and have evolved prehensile tails that can hold their entire body weight. It is among this group that we see semi-brachiators, like the spider monkey (see Figure 6.13). To make them more efficient in this form of locomotion, spider monkeys evolved to not have thumbs so that their hands work more like hooks that can easily let go of branches while swinging. Howler monkeys are another well-known member of this group, earning their name due to their loud calls, which can be heard miles away. To make these loud vocalizations, howler monkeys have a specialized vocal system that includes a large larynx and hyoid bone. Howler monkeys are the most folivorous of the platyrrhines and are known for spending a large portion of their day digesting their food.<\/p>\n<figure style=\"width: 458px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image33-1.jpg\" alt=\"Four platyrrhine species.\" width=\"458\" height=\"457\" \/><figcaption class=\"wp-caption-text\">Figure 6.30: Clockwise from top right: howler monkey, woolly monkey, woolly spider monkey, and spider monkey. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Atelidae_Family.jpg\" target=\"_blank\">Atelidae Family<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Miguelrangeljr\" target=\"_blank\">Miguelrangeljr<\/a> is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0 License<\/a>. [Includes <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Ateles_marginatus_(Sao_Paulo_zoo).jpg\" target=\"_blank\">Ateles marginatus (Sao Paulo zoo)<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Miguelrangeljr\" target=\"_blank\">Miguelrangeljr<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Alouatta_caraya_male.JPG\" target=\"_blank\">Alouatta caraya male<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Miguelrangeljr\" target=\"_blank\">Miguelrangeljr<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Lagothrix_lagotricha_(walking).jpg\" target=\"_blank\">Lagothrix lagotricha (walking)<\/a> by Hans Hillewaert, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Brachyteles_hypoxanthus2.jpg\" target=\"_blank\">Brachyteles hypoxanthus2<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/42956474@N04\/with\/4133258867\/\" target=\"_blank\">Paulo B. Chaves<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/legalcode\" target=\"_blank\">CC BY 2.0<\/a>.]<\/figcaption><\/figure>\n<p class=\"import-Normal\">There are many other monkeys in Central and South America, including the gregarious capuchins (see Figure 6.28) and squirrel monkeys, the pair-living titi monkeys, and the nocturnal owl monkeys. There are also the seed-eating saki monkeys and uakaris. In many areas across Central and South America, multiple species of platyrrhines share the forests, with some even traveling together in association. According to molecular evidence, the diversity of platyrrhines that we see today seems to have originated about 25 million years ago (Schneider &amp; Sampaio 2015). Figure 6.31 summarizes the key traits of platyrrhines relative to the other infraorders of Haplorrhini.<\/p>\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<caption>Figure 6.31: Platyrrhini at a glance: Summary of the key traits we use to distinguish platyrrhines. Traits indicated with an * are those with exceptions detailed in the text. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\" target=\"_blank\">Platyrrhini at a glance table (Figure 5.29)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/caption>\n<tbody>\n<tr class=\"a3-R\">\n<td class=\"a3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Platyrrhini traits<\/strong><\/p>\n<\/td>\n<\/tr>\n<tr class=\"a3-R\">\n<td class=\"a3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Flat nose with rounded nostrils pointing to the side<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Highly arboreal<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Less sexually dimorphic on average<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">2:1:3:3 dental formula*<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Polymorphic colour vision*<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h4 class=\"import-Normal\"><em>Infraorder Catarrhini of Asia and Africa <\/em><\/h4>\n<figure style=\"width: 191px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image34.jpg\" alt=\"Wolf\u2019s guenon.\" width=\"191\" height=\"287\" \/><figcaption class=\"wp-caption-text\">Figure 6.32: A Wolf\u2019s guenon demonstrating a typical catarrhine nose with teardrop-shaped nostrils close together and pointed downward. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Wolf&apos;s_Guenon_Picking_Up_Food_(19095137693).jpg\" target=\"_blank\">Wolf's Guenon Picking Up Food (19095137693)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/8749778@N06\" target=\"_blank\">Eric Kilby<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\" target=\"_blank\">CC BY-SA 2.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Infraorder Catarrhini includes Superfamily Cercopithecoidea (the monkeys of Africa and Asia) and Superfamily Hominoidea (apes and humans). Nonhuman catarrhines are found all over Africa and South and Southeast Asia, with some being found as far north as Japan. The most northerly and southerly catarrhines are cercopithecoid monkeys. In contrast, apes are less tolerant of drier, more seasonal environments and so have a relatively restricted geographic range.<\/p>\n<p class=\"import-Normal\">Relative to other haplorrhine infraorders, catarrhines are distinguished by several characteristics. Catarrhines have a distinctive nose shape, with teardrop-shaped nostrils that are close together and point downward (Figure 6.32) and one fewer premolar than most other primates, giving us a dental formula of 2:1:2:3 (Figure 6.33). On average, catarrhines are the largest and most sexually dimorphic of all primates. Gorillas are the largest living primates, with males weighing up to 220 kg. The most sexually dimorphic of all primates are mandrills. Mandrill males not only have much more vibrant colouration than mandrill females but also have larger canines and can weigh up to three times more (Setchell Et al. 2001). The larger body size of catarrhines is related to the more terrestrial lifestyle of many members of this infraorder. In fact, the most terrestrial of living primates can be found in this group. Among all primates, vision is the most developed in catarrhines. Catarrhines independently evolved the same adaptation as howler monkeys in having each X chromosome with genes to distinguish both reds and yellows, so all male and female catarrhines are trichromatic, which is useful for these diurnal primates.<\/p>\n<figure style=\"width: 632px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image35-1.jpg\" alt=\"Platyrrhine, cercopithecoid, and hominoid mandibles.\" width=\"632\" height=\"331\" \/><figcaption class=\"wp-caption-text\">Figure 6.33: Catarrhines have two premolars whereas most other primate taxa (including platyrrhini) have three premolars. This image also shows one of the derived traits of cercopithecoids, their bilophodont molars, which differ from the more ancestral Y-5 molars of apes and humans. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\" target=\"_blank\">Platyrrhini vs. Catarrhini dentition<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\" target=\"_blank\">CC BY-NC-SA 4.0 License<\/a>. [Includes <a href=\"https:\/\/animaldiversity.org\/accounts\/Animalia\/specimens\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Cebus_apella\/lower_dorsal2216\/?start=135;f=subject::specimen::lower%20jaw\" target=\"_blank\">Cebus apella (brown capuchin)<\/a> at Animal Diversity Web by <a href=\"https:\/\/animaldiversity.org\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Hylobates_syndactylus\/lower_dorsal0097\/\" target=\"_blank\">Phil Myers<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\" target=\"_blank\">CC BY-NC-SA 3.0<\/a>; <a href=\"https:\/\/animaldiversity.org\/accounts\/Animalia\/specimens\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Lophocebus_albigena\/lower_dorsal2060\/?start=525;f=subject::specimen::lower%20jaw\" target=\"_blank\">Lophocebus albigena (gray-cheeked mangaby)<\/a> at Animal Diversity Web by <a href=\"https:\/\/animaldiversity.org\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Hylobates_syndactylus\/lower_dorsal0097\/\" target=\"_blank\">Phil Myers<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\" target=\"_blank\">CC BY-NC-SA 3.0<\/a>; <a href=\"https:\/\/animaldiversity.org\/accounts\/Primates\/specimens\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Hylobates_syndactylus\/lower_dorsal0097\/?start=105;f=subject::specimen::lower%20jaw\" target=\"_blank\">Symphalangus syndactylus (siamang)<\/a> at Animal Diversity Web by <a href=\"https:\/\/animaldiversity.org\/collections\/contributors\/phil_myers\/ADW_mammals\/specimens\/Primates\/Hylobates_syndactylus\/lower_dorsal0097\/\" target=\"_blank\">Phil Myers<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\" target=\"_blank\">CC BY-NC-SA 3.0<\/a>.]<\/figcaption><\/figure>\n<p class=\"import-Normal\">The two superfamilies of catarrhines\u2014Superfamily Cercopithecoidea, the monkeys of Africa and Asia, and Superfamily Hominoidea, which includes apes and humans\u2014are believed to have split about 32 million years ago based on molecular evidence (Pozzi Et al. 2014). This fits with the fossil record, which shows evidence of these lineages by about 25 million years ago (see Chapters 8-9).<\/p>\n<h4 class=\"import-Normal\"><em>Superfamily Cercopithecoidea of Africa and Asia<\/em><\/h4>\n<figure style=\"width: 285px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image36-1.jpg\" alt=\"Pinkish ischial callosities on a crested black macaque.\" width=\"285\" height=\"214\" \/><figcaption class=\"wp-caption-text\">Figure 6.34: The second derived trait of cercopithecoids are their ischial callosities, shown here on a crested black macaque. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Sulawesi_trsr_DSCN0572_v1.JPG\" target=\"_blank\">Sulawesi trsr DSCN0572 v1<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Shankar_Raman\" target=\"_blank\">T. R. Shankar Ramanis<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0 License.<\/a><\/figcaption><\/figure>\n<p>Compared to hominoids, cercopithecoids have an ancestral quadrupedal body plan with two key derived traits. The first derived trait of cercopithecoids is their <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1422\">bilophodont<\/a> <\/strong>molars (\u201cbi\u201d meaning two, \u201cloph\u201d referring to ridge, and \u201cdont\u201d meaning tooth). If you refer back to Figure 6.33, you will see how the molars of cercopithecoids have four cusps arranged in a square pattern and have two ridges connecting them. It is thought that this molar enabled these monkeys to eat a wide range of foods, thus allowing them to live in habitats that apes cannot. The other key derived trait that all cercopithecoids share is having <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1424\">ischial callosities<\/a> <\/strong>(Figure 6.34). The ischium is the part of your pelvis that you are sitting on right now (see Appendix A: Osteology). In cercopithecoids, this part of the pelvis has a flattened surface that, in living animals, has callused skin over it. These function as seat pads for cercopithecoids, who often sit above branches when feeding and resting.<\/p>\n<figure style=\"width: 359px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image37-1.png\" alt=\"Areas of Europe, Asia, Africa, and Australia where cercopithecoids live.\" width=\"359\" height=\"277\" \/><figcaption class=\"wp-caption-text\">Figure 6.35: Geographic distribution of the cercopithecoid monkeys. Catarrhines have the widest geographic distribution due to the success of cercopithecoids who are found all across subsaharan Africa and southern Asia. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\" target=\"_blank\">Superfamily Cercopithecoidea map (Figure 5.33)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Elyssa Ebding at <a href=\"https:\/\/www.csuchico.edu\/geop\/geoplace\/index.shtml\" target=\"_blank\">GeoPlace, California State University, Chico<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p>Cercopithecoid monkeys are the most geographically widespread group of nonhuman primates (Figure 6.35). Since their divergence from hominoids, this monkey group has increased in numbers and diversity due, in part, to their fast reproductive rates. On average, cercopithecoids will reproduce every one to two years, whereas hominoids will reproduce once every four to nine years, depending on the taxon.<\/p>\n<figure style=\"width: 180px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image38-1.jpg\" alt=\"Two silver leaf monkeys hold orange-haired infants.\" width=\"180\" height=\"240\" \/><figcaption class=\"wp-caption-text\">Figure 6.36: Silver leaf monkey infants are born with orange fur, dramatically contrasting the adult coat colour of their mothers. After a few months, the infants gradually change colour to that of their parents. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Silverleaf_Monkey_(Kuala_Lumpur).jpg\" target=\"_blank\">Silverleaf Monkey (Kuala Lumpur)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/10815162@N07\" target=\"_blank\">Andrea Lai<\/a> from Auckland, New Zealand, is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/legalcode\" target=\"_blank\">CC BY 2.0 License.<\/a><\/figcaption><\/figure>\n<p>Cercopithecoidea is split into two groups, the leaf monkeys and the cheek-pouch monkeys. Both groups coexist in Asia and Africa; however, the majority of leaf monkey species live in Asia with only a few taxa in Africa. In contrast, only one genus of cheek-pouch monkey lives in Asia, and all the rest of them in Africa. As you can probably guess based on their names, the two groups differ in terms of diet. Leaf monkeys are primarily folivores, with some species eating a significant amount of seeds. Cheek-pouch monkeys tend to be more frugivorous or omnivorous, with one taxon, geladas, eating primarily grasses. The two groups also differ in some other interesting ways. Leaf monkeys tend to produce infants with <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1426\">natal coats<\/a><\/strong>\u2014infants whose fur is a completely different colour from their parents (Figure 6.36). Leaf monkeys are also known for having odd noses (Figure 6.37), and so they are sometimes called \u201codd-nosed monkeys.\u201d Cheek-pouch monkeys are able to pack food into their cheek pouches (Figure 6.38), thus allowing them to move to a location safe from predators or aggressive individuals of their own species where they can eat in peace.<\/p>\n<figure style=\"width: 408px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image39.jpg\" alt=\"Male proboscis monkey.\" width=\"408\" height=\"272\" \/><figcaption class=\"wp-caption-text\">Figure 6.37: Proboscis monkeys are one of several \u201codd-nosed\u201d leaf monkeys. Male proboscis monkeys, like this one, have large, pendulous noses, while females have much smaller noses. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Proboscis_monkey_(Nasalis_larvatus)_male_head.jpg\" target=\"_blank\">Proboscis monkey (Nasalis larvatus) male head<\/a> by <a href=\"https:\/\/www.sharpphotography.co.uk\/\" target=\"_blank\">Charles J Sharp<\/a> creator QS:P170,Q54800218 is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\" target=\"_blank\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<figure style=\"width: 414px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image40-1.jpg\" alt=\"Bonnet macaque with full cheek pouches.\" width=\"414\" height=\"275\" \/><figcaption class=\"wp-caption-text\">Figure 6.38: This bonnet macaque has filled its cheek pouches with food, an adaptation that is useful in transporting food to a safer location to eat. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Bonnet_macaque_DSC_0893.jpg\" target=\"_blank\">Bonnet macaque DSC 0893<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Shankar_Raman\" target=\"_blank\">T. R. Shankar Raman<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\" target=\"_blank\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<h4 class=\"import-Normal\"><em>Superfamily Hominoidea of Africa and Asia<\/em><\/h4>\n<figure style=\"width: 438px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image41.png\" alt=\"Areas of Europe, Asia, Africa, and Australia where hominoidea live.\" width=\"438\" height=\"339\" \/><figcaption class=\"wp-caption-text\">Figure 6.39: Geographic distribution of apes across Central and West Africa and Southeast Asia. Hominoids overlap geographically with cercopithecoid monkeys but have a lower tolerance for seasonal environments and so are found only in tropical forests across these regions. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\" target=\"_blank\">Superfamily Hominoidea map (Figure 5.38)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Elyssa Ebding at <a href=\"https:\/\/www.csuchico.edu\/geop\/geoplace\/index.shtml\" target=\"_blank\">GeoPlace, California State University, Chico<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Superfamily Hominoidea of Africa and Asia (Figure 6.39) includes the largest of the living primates: apes and humans. Whereas cercopithecoid monkeys have bilophodont molars, hominoids have the more ancestral <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1428\">Y-5 molars<\/a><\/strong>, which feature five cusps separated by a \u201cY\u201d-shaped groove pattern (see Figure 6.33). The Y-5 molar was present in the common ancestors of hominoids and cercopithecoids, thus it is the more ancestral molar pattern of the two. Hominoids differ the most from other primates in our body plans, due to the unique form of locomotion that hominoids are adapted for: brachiation (Figure 6.40).<\/p>\n<p>To successfully swing below branches, many changes to the body needed to occur. Hominoid arms are much longer than the legs to increase reach, and the lower back is shorter and less flexible to increase control when swinging. The torso, shoulders, and arms of hominoids have evolved to increase range of motion and flexibility (see again Figure 6.12). The clavicle, or collar bone, is longer to stabilize the shoulder joint out to the side, thus enabling us to rotate our arms 360 degrees. Hominoid rib cages are wider side to side and shallower front to back than those of cercopithecoids and we do not have tails, as tails are useful for balance when running on all fours but generally not useful while swinging. Hominoids also have modified ulnae, one of the two bones in the forearm (see Appendix A: Osteology). At the elbow end of the ulna, hominoids have a short <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1430\">olecranon process<\/a><\/strong>, which allows for improved extension in our arms. At the wrist end of the ulna, hominoids have a short <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1432\">styloid process<\/a><\/strong>, which enables us to have very flexible wrists, a trait critical for swinging. Both the olecranon process and styloid process are long in quadrupedal animals who carry much of their weight on their forelimbs when traveling and who therefore need greater stability rather than flexibility in those joints.<\/p>\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<caption>Figure 6.40: Quadrupedalism vs. brachiation: Summary of the key anatomical differences between a quadrupedal primate and one adapted for brachiation. To view these traits using photos of bones, check out the interactive skeletal websites in \u201cFurther Explorations\u201d below. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\" target=\"_blank\">Quadrupedalism vs. Brachiation table (Figure 5.39)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/caption>\n<thead>\n<tr>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Quadrupedalism<\/strong><\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Brachiation<\/strong><\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"a4-R\">\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Arm length vs. leg length<\/strong><\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">About equal<\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Arms are longer<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a4-R\">\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Shoulder position<\/strong><\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">More on the front<\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Out to the side<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a4-R\">\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Ribcage shape<\/strong><\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Deep front-to-back<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Narrow side-to-side<\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Shallow front-to-back<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Wide side-to-side<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a4-R\">\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Length of lower back<\/strong><\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Long<\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Short<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a4-R\">\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Collar bone length<\/strong><\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Short<\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Long<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a4-R\">\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Ulnar olecranon process<\/strong><\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Long<\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Short<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a4-R\">\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Ulnar styloid process<\/strong><\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Long<\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Short<\/p>\n<\/td>\n<\/tr>\n<tr class=\"a4-R\">\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Tail<\/strong><\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Short to long<\/p>\n<\/td>\n<td class=\"a4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">None<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p class=\"import-Normal\">Apes and humans also differ from other primates in behaviour and life history characteristics. Hominoids all seem to show some degree of female dispersal at sexual maturity but, as you will learn in Chapter 7, it is more common that males leave. Some apes show males dispersing in addition to females, but the hominoid tendency for female dispersal is a bit unusual among primates. Our superfamily is also characterized by the most extended life histories of all primates. All members of this group take a long time to grow and reproduce much less frequently compared to cercopithecoids. The slow pace of this life history is likely related to why hominoids have decreased in diversity since they first evolved. Figure 6.41 summarizes the key traits of Infraorder Catarrhini and its two superfamilies. Today, there are only five types of hominoids left: gibbons and siamangs, orangutans, gorillas, chimpanzees and bonobos, and humans.<\/p>\n<table class=\"aligncenter\">\n<caption>Figure 6.41a: Catarrhini at a glance: Summary of key traits of the Infraorder Catarrhini. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\" target=\"_blank\">Catarrhini at a glance (Figure 5.40)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>. [Includes <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Duskyleafmonkey1.jpg\" target=\"_blank\">Duskyleafmonkey1<\/a> by <a href=\"https:\/\/www.the-ninth.com\/about\" target=\"_blank\">Robertpollai<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by\/3.0\/at\/deed.en\" target=\"_blank\">CC BY 3.0 AT<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Male_Bornean_Orangutan_-_Big_Cheeks.jpg\" target=\"_blank\">Male Bornean Orangutan - Big Cheeks<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/8749778@N06\" target=\"_blank\">Eric Kilby<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\" target=\"_blank\">CC BY-SA 2.0<\/a>.]<\/caption>\n<thead>\n<tr style=\"height: 22pt\">\n<td class=\"a5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\" colspan=\"2\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Infraorder Catarrhini<\/strong><\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"a5-R\" style=\"height: 22pt\">\n<td class=\"a5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\" colspan=\"2\">\n<p class=\"import-Normal\" style=\"text-align: center\">Downward facing, tear-drop shaped nostrils, close together<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Arboreal and more terrestrial taxa<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">On average, largest primates<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">On average, most sexually dimorphic taxonomic group<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">2:1:2:3 dental formula<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">All trichromatic<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<caption>Figure 6.41b: Characteristics used to distinguish between the two Catarrhini superfamilies. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-4\/\" target=\"_blank\">Catarrhini at a glance (Figure 5.40)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Stephanie Etting is a collective work under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>. [Includes <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Duskyleafmonkey1.jpg\" target=\"_blank\">Duskyleafmonkey1<\/a> by <a href=\"https:\/\/www.the-ninth.com\/about\" target=\"_blank\">Robertpollai<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by\/3.0\/at\/deed.en\" target=\"_blank\">CC BY 3.0 AT<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Male_Bornean_Orangutan_-_Big_Cheeks.jpg\" target=\"_blank\">Male Bornean Orangutan - Big Cheeks<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/8749778@N06\" target=\"_blank\">Eric Kilby<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\" target=\"_blank\">CC BY-SA 2.0<\/a>.]<\/caption>\n<thead>\n<tr>\n<td class=\"a5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong><img class=\"alignnone\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image42-1.jpg\" alt=\"Dusky leaf monkey\" width=\"248\" height=\"186\" \/><\/strong><strong>Superfamily Cercopithecoidea<\/strong><\/p>\n<\/td>\n<td class=\"a5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong><img class=\"alignnone\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image43-1.jpg\" alt=\"Orangutan\" width=\"274\" height=\"183\" \/><\/strong><strong>Superfamily Hominoidea<\/strong><\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"a5-R\">\n<td class=\"a5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Wide geographic distribution<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Bilophodont molars<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Ischial callosities<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Reproduce every 1\u20132 years<\/p>\n<\/td>\n<td class=\"a5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"text-align: center\">Tropical forests of Africa and Asia<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Y-5 molars<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Adaptations for brachiation<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Reproduce every 4\u20139 years<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h4 class=\"import-Normal\"><em>Family <\/em>Hylobatidae <em>of Southeast Asia<\/em><\/h4>\n<figure style=\"width: 441px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image44-1.jpg\" alt=\"Siamang with outstretched arms.\" width=\"441\" height=\"294\" \/><figcaption class=\"wp-caption-text\">Figure 6.42: Siamangs are the largest of the Hylobatidae family. They are all black with a throat sac that can become inflated to give out loud calls. Credit: <a href=\"https:\/\/www.flickr.com\/photos\/suneko\/373310729\/\" target=\"_blank\">Shout (373310729)<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/suneko\/\" target=\"_blank\">su neko<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/\" target=\"_blank\">CC BY-SA 2.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">The number of genera in this group has been changing in recent years, but the taxa broadly encompasses gibbons and siamangs. Both are found across Southeast Asian tropical forests. Gibbons weigh, on average, about 13 pounds and tend to be more frugivorous, whereas siamangs are larger than gibbons and also more folivorous. Unlike the larger-bodied apes (orangutans, chimps, bonobos, and gorillas) who make nests to sleep in every night, gibbons and siamangs will develop callused patches on their ischium resembling ischial callosities. Gibbon species are quite variable in their colouration and markings, while siamangs are all black with big throat sacs that are used in their exuberant vocalizations (Figure 6.42). Both gibbons and siamangs live in pairs with very little sexual dimorphism, although males and females do differ in colouration in some gibbon species.<\/p>\n<h4 class=\"import-Normal\">Pongo<em> of Southeast Asia<\/em><\/h4>\n<p class=\"import-Normal\">The Genus <em>Pongo <\/em>refers to orangutans. These large red apes are found in Southeast Asia, with the two well-known species each living on the islands of Borneo and Sumatra. A third, very rare species, was recently discovered in Southern Sumatra (Nater Et al. 2017). Orangutans are highly frugivorous but will supplement their diet with leaves and bark when fruit is less available. As mentioned earlier, orangutans are the only diurnal, solitary taxon among primates and are extremely slow to reproduce, producing only one offspring about every seven to nine years. They are highly sexually dimorphic (Figure 6.43 a &amp; b), with fully developed, \u201cflanged\u201d males being approximately twice the size of females. These males have large throat sacs; long, shaggy coats; and cheek flanges. The skulls of male orangutans often feature a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1434\">sagittal crest<\/a><\/strong>, which is believed to function as additional attachment area for chewing muscles as well as a trait used in sexual competition (Balolia, Soligo, &amp; Wood 2017). An unusual feature of orangutan biology is <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1436\">male bimaturism<\/a><\/strong>. Male orangutans are known to delay maturation until one of the more dominant, flanged males disappears. The males that delay maturation are called \u201cunflanged\u201d males, and they can remain in this state for their entire life. Unflanged males resemble females in their size and appearance and will sneak copulations with females while avoiding the bigger, flanged males. Flanged and unflanged male orangutans represent alternative reproductive strategies, both of which successfully produce offspring (Utami Et al. 2002).<\/p>\n<p>&nbsp;<\/p>\n<\/div>\n<figure id=\"attachment_181-19\" aria-describedby=\"caption-attachment-181-19\" style=\"width: 1900px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-180 size-full\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/5.43.jpg\" alt=\"a. Female orangutan with infant. b. Male orangutan in a tree.\" width=\"1900\" height=\"800\" \/><figcaption id=\"caption-attachment-181-19\" class=\"wp-caption-text\">Figure 6.43: (a) A female orangutan eating fruit with her infant nearby and (b) a flanged adult male eating leaves. Male orangutans are about twice the size of females and have a longer coat length, cheek flanges, and throat sac. Credit: 6.43a. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Orang_Utan_(Pongo_pygmaeus)_female_with_baby_(8066259067).jpg\" target=\"_blank\">Orang Utan (Pongo pygmaeus) female with baby (8066259067)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/65695019@N07\" target=\"_blank\">Bernard DUPONT<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/\" target=\"_blank\">CC BY-SA 2.0 Licence<\/a>. 6.43b. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Orangutan_-Zoologischer_Garten_Berlin-8a.jpg\" target=\"_blank\">Orangutan -Zoologischer Garten Berlin-8a<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/37088680@N03\" target=\"_blank\">David Forsman<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/\" target=\"_blank\">CC BY 2.0 License<\/a>.<\/figcaption><\/figure>\n<div class=\"learning-objectives\">\n<h4 class=\"import-Normal\">Gorilla <em>of Africa<\/em><\/h4>\n<p class=\"import-Normal\">There are several species of gorillas that can be found across Central Africa. Gorilla males, like orangutan males, are about twice the size of female gorillas (Figures 6.44a &amp; b). When on the ground, gorillas use a form of quadrupedalism called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1438\">knuckle-walking<\/a><\/strong>, wherein the fingers are curled under and the weight is carried on the knuckles. Male gorillas have a large sagittal crest and large canines compared with females. Adult male gorillas are often called \u201csilverbacks\u201d because when they reach about twelve to thirteen years old, the hair on their backs turns silvery grey. Gorillas typically live in groups of one male and several females. Gorillas are considered folivorous, although some species can be more frugivorous depending on fruit seasonality (Remis 1997).<\/p>\n<\/div>\n<figure id=\"attachment_181-20\" aria-describedby=\"caption-attachment-181-20\" style=\"width: 1900px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-181 size-full\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/5.44.jpg\" alt=\"a. Female gorilla with offspring. b. Male gorilla.\" width=\"1900\" height=\"800\" \/><figcaption id=\"caption-attachment-181-20\" class=\"wp-caption-text\">Figure 6.44: (a) A female gorilla with her two offspring and (b) a silverback adult male. Male gorillas are about twice the size of females. They also differ from females in having a large sagittal crest and a silver back, which appears as they mature. Credit: 6.44a. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Enzo_naomi_echo.jpg\" target=\"_blank\">Enzo naomi echo<\/a> by Zoostar is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/3.0\/legalcode\" target=\"_blank\">CC BY 3.0 License<\/a>. 6.44b. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Male_gorilla_in_SF_zoo.jpg\" target=\"_blank\">Male gorilla in SF zoo<\/a> by Brocken Inaglory is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<div class=\"learning-objectives\">\n<h4 class=\"import-Normal\">Pan<em> of Africa<\/em><\/h4>\n<figure style=\"width: 252px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image49-1.jpg\" alt=\"Bonobo looks away from the camera.\" width=\"252\" height=\"222\" \/><figcaption class=\"wp-caption-text\">Figure 6.45: Bonobo (Pan paniscus). You can see the distinctive hair-part on this bonobo. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Bonobo_male_Jasongo_15yo_Twycross_582a_(2014_11_14_01_04_18_UTC).jpg\" target=\"_blank\">Bonobo male Jasongo 15yo Twycross 582a (2014 11 14 01 04 18 UTC)<\/a> by William H. Calvin is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\" target=\"_blank\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<p>The Genus <em>Pan <\/em>includes two species: <em>Pan troglodytes <\/em>(the common chimpanzee) and <em>Pan paniscus <\/em>(the bonobo). These species are separated by the Congo River, with chimpanzees ranging across West and Central Africa and bonobos located in a restricted area south of the Congo River. Chimpanzees and bonobos both have broad, largely frugivorous diets.The two species differ morphologically in that bonobos are slightly smaller, have their hair parted down the middle of their foreheads, and are born with dark faces (Figure 6.45). In contrast, chimpanzees do not have the distinctive parted hair and are born with light faces that darken as they mature (Figure 6.46). Chimpanzees and bonobos live in a grouping called a fission-fusion community, which you will learn more about in Chapter 6. Both species are moderately sexually dimorphic, with males about 20% larger than females. When on the ground, chimpanzees and bonobos knuckle-walk like gorillas do.<\/p>\n<figure style=\"width: 418px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image50-1.jpg\" alt=\"Female chimpanzee with offspring in a tree.\" width=\"418\" height=\"278\" \/><figcaption class=\"wp-caption-text\">Figure 6.46: A common chimpanzee (Pan troglodytes) female (centre) and her offspring. Note the pink face of the youngest individual. Bonobos are born with dark-skinned faces, but chimpanzees are born with pink faces that darken with age. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Chimpanzees_in_Uganda_(5984913059).jpg\" target=\"_blank\">Chimpanzees in Uganda (5984913059)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/57424551@N06\" target=\"_blank\">USAID Africa Bureau<\/a> uploaded by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Elitre\" target=\"_blank\">Elitre<\/a> is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\" target=\"_blank\">public domain<\/a>.<\/figcaption><\/figure>\n<h4 class=\"import-Normal\">Homo<\/h4>\n<p class=\"import-Normal\">The last member of the Hominoidea to discuss is our own taxon, Genus <em>Homo<\/em>. Later chapters will discuss the many extinct species of <em>Homo<\/em>, but today there is only one living species of <em>Homo, <\/em>our own species, <em>sapiens<\/em>. While it is interesting to focus on how humans differ from apes in many aspects of our morphology, behaviour, and life history, one objective of this chapter, and of biological anthropology in general, is to understand our place in nature. This means looking for aspects of human biology that link us to the taxonomic diversity we have discussed. To that end, here we will focus on similarities humans share with other hominoids.<\/p>\n<p class=\"import-Normal\">Like other hominoids, humans lack a tail and possess upper-body adaptations for brachiation. While our lower body has been modified for a bipedal gait, we are still able to swing from branches and throw a baseball, all thanks to our mobile shoulder joint. Humans, like other hominoids, also have a Y-5 cusp pattern on our molars. All hominoids, including humans, have an extended life history, taking time to grow and develop, and reproducing slowly over a long life span. Lastly, while humans show a great deal of variation across cultures, many human societies show tendencies for female dispersal (Burton Et al. 1996).<\/p>\n<p class=\"import-Normal\">Among the hominoids, humans show particular affinities with other members of the African Clade, <em>Pan <\/em>and <em>Gorilla<\/em>. Humans share over 96% of our DNA with gorillas (Scally Et al. 2012), and over 98% with <em>Pan <\/em>(Ebersberger Et al. 2002). Even without this strong genetic evidence, the African Clade of hominoids share many morphological similarities, including having wide-set eye sockets and backward-sweeping cheekbones. Today, <em>Pan<\/em> and <em>Gorilla<\/em> knuckle-walk when on the ground, and it has been suggested the last common ancestor of chimpanzees, bonobos, gorillas, and humans did as well (Richmond, Begun, &amp; Strait 2001). Further, humans, chimpanzees, and bonobos all live in fission-fusion social groups characterized by shared behaviours, like male cooperation in hunting and territoriality, as well as tool use.<\/p>\n<div class=\"textbox\">\n<h2 class=\"import-Normal\">Special Topic: Primates in Culture and Religion<\/h2>\n<p class=\"import-Normal\">One of the best parts of teaching anthropology for me is getting to spend time watching primates at zoos. What I also find interesting is watching people watch primates. I have very often heard a parent and child walk up to a chimpanzee enclosure and exclaim \u201cLook at the monkeys!\u201d The parent and child often don\u2019t know that a chimpanzee is not a monkey, nor are they likely to know that chimpanzees share more than 98% of their DNA with us. What strikes me as significant is that, although most people do not know the difference between a monkey, an ape, and a lemur, they nonetheless recognize something in the animals as being similar to themselves. In fact, recognition of similarities between humans and other primates is very ancient, dating back far earlier than Linnaeus. For many of us, we only ever get to see primates in zoos and animal parks, but in many areas of the world, humans have coexisted with these animals for thousands of years. In areas where humans and primates have a long, shared history, nonhuman primates often play key roles in creation myths and cultural symbolism.<\/p>\n<p class=\"import-Normal\">Hamadryas baboons feature significantly in Ancient Egyptian iconography. Ancient Egyptian deities and beliefs transformed over time, as did the role of hamadryas baboons. Early on, baboons were thought to represent dead ancestors, and one monkey deity, called Babi or Baba, was thought to feed off of dead souls. Later, baboons became the totem animal for Thoth, the deity of science, writing, wisdom, and measurement, who also wrote the Book of the Dead. Sunbathing hamadryas baboons led ancient Egyptians to associate them with Ra, the sun god, who was the son of Thoth. During mummification, human organs were removed and put into canopic jars, one of which was topped with the head of the baboon-headed god, Hapi. Hamadryas baboons were also often kept as pets, as depicted in hieroglyphics, and occasionally mummified as well.<\/p>\n<p class=\"import-Normal\">On Madagascar, indris and aye-ayes play roles in the creation myths and omens of local people.There are many myths regarding the origins of indris and their relationship to humans, including one where two brothers living in the forest separated, with one brother leaving the forest and becoming a human while the other stayed in the forest to become the indri. Like humans, indris have long legs, no tail, and upright posture. They are considered sacred and are therefore protected. Unfortunately, the aye-aye is not treated with the same reverence. Because of their unusual appearance (see Figure 6.15), aye-ayes are seen as omens of death.They are usually killed when encountered because it is believed that someone will die if an aye-aye points at them.<\/p>\n<p class=\"import-Normal\">In India, monkeys play a key role in the Hindu religion. Hanuman, who resembles a monkey, is a key figure in the Ramayana. Hanuman is thought to be a guardian deity, and so local monkeys like Hanuman langurs and macaques are protected in India (Figure 6.47). In Thailand, where Hinduism is also practiced, the Hindu reverence for monkeys extends to \u201cmonkey feasts,\u201d where large quantities of food are spread out in gratitude to the monkeys for bringing good fortune.<\/p>\n<figure style=\"width: 308px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image51-1.jpg\" alt=\"Three macaques outside a temple in India.\" width=\"308\" height=\"261\" \/><figcaption class=\"wp-caption-text\">Figure 6.47: Because of important monkey-like figures in the Hindu religion, macaques are protected in India and often live near temples where they are fed by local peoples. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Macaque_India_4.jpg\" target=\"_blank\">Macaque India 4<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Mosmas\" target=\"_blank\">Thomas Schoch<\/a> (<a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Mosmas\" target=\"_blank\">Mosmas<\/a>) is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/\" target=\"_blank\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">The people of Japan have coexisted with Japanese macaques for thousands of years, and so monkeys play key roles in both of the major Japanese religions. In the Shinto religion, macaques are thought of as messengers between the spirit world and humans, and monkey symbols are thought to be good luck. The other major religion in Japan is Buddhism, and monkeys play a role in symbolism of this religion as well. The \u201cThree Wise Monkeys\u201d who see no evil, speak no evil, and hear no evil derive from Buddhist iconography of monkeys.<\/p>\n<p class=\"import-Normal\">In Central and South America, monkeys feature often in Mayan and Aztec stories. In the Mayan creation story, the Popol Vuh, the \u201chero brothers,\u201d are actually a howler monkey and a spider monkey, who represent ancestors of humans in the story. In the Aztec religion, spider monkeys are associated with the god of arts, pleasure, and playfulness. A spider monkey is also represented in a Peruvian Nazca geoglyph, a large design made on the ground by moving rocks.<\/p>\n<p class=\"import-Normal\">In many of these regions today, the relationships between humans and nonhuman primates are complicated. The bushmeat and pet trades make these animals valuable at the expense of many animals\u2019 lives, and in some areas, nonhuman primates have become pests who raid crop fields and consume valuable foods. All of this has led to the development of a new subarea of anthropology called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1440\">Ethnoprimatology<\/a><\/strong>, which involves studying the political, economic, symbolic, and practical relationships between humans and nonhuman primates.This field highlights the particular challenges for humans of having to coexist with animals with whom we share so much in common. It also provides insight into some of the challenges facing primate conservation efforts (see Appendix B: Primate Conservation).<\/p>\n<\/div>\n<h2 class=\"import-Normal\">Summary<\/h2>\n<p class=\"import-Normal\">The Order Primates is a diverse and fascinating group of animals united in sharing a suite of characteristics\u2014visual specialization, grasping hands and feet, large brains, and extended life histories\u2014that differentiates us from other groups of mammals. In this chapter, we surveyed the major taxonomic groups of primates, discussing where humans fit among our close relatives as well as discovering that primates are interesting animals in their own right. We discussed a range of key traits used to distinguish between the many taxa of living primates, including dietary, locomotor, and behavioural characteristics. Because of our long, shared evolutionary history with these animals, nonhuman primates provide a crucial resource for understanding our current biology. In Chapter 7, you will discover the fascinating and complex social behaviours of nonhuman primates, which provide further insight into our evolutionary biology.<\/p>\n<\/div>\n<h2>Expand your view<\/h2>\n<p>For a deeper look into primate conservation and contemporary issues of endangerment\/extinction see <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/appendix-b-primate-conservation\/\">Appendix B<\/a><\/p>\n<p>&nbsp;<\/p>\n<div class=\"learning-objectives\">\n<div class=\"textbox shaded\">\n<h2 class=\"import-Normal\">Review Questions<\/h2>\n<ul>\n<li class=\"import-Normal\">Why does the field of anthropology, a field dedicated to the study of humans, include the study of nonhuman animals? What can we learn from nonhuman primates?<\/li>\n<li class=\"import-Normal\">Why is it important to try to place taxa into a clade classification rather than groupings based on grade? Can you think of an example?<\/li>\n<li class=\"import-Normal\">One of the important goals of an introductory biological anthropology course is to teach you about your place in nature. What is the full taxonomic classification of humans, and what are some of the traits we have of each of these categories?<\/li>\n<li class=\"import-Normal\">When you have seen primates in person, did you observe any facial expressions, behaviours, or physical traits that seemed familiar to you? If so, which ones and why?<\/li>\n<li class=\"import-Normal\">Draw out a tree showing the major taxonomic group of primates described here, making sure to leave room in between each level. Underneath each taxon, list some of the key features of this group so that you can compare traits between groups.<\/li>\n<\/ul>\n<\/div>\n<h2 class=\"import-Normal\">Key Terms<\/h2>\n<p class=\"import-Normal\"><strong>Activity pattern<\/strong>: Refers to the time of day an animal is typically active.<\/p>\n<p class=\"import-Normal\"><strong>African clade<\/strong>: A grouping that includes gorillas, chimpanzees, bonobos, humans, and their extinct relatives.<\/p>\n<p class=\"import-Normal\"><strong>Analogy<\/strong>: When two or more taxa exhibit similar traits that have evolved independently, the similar traits evolve due to similar selective pressures. (Also sometimes called convergent evolution, parallel evolution, or homoplasy.)<\/p>\n<p class=\"import-Normal\"><strong>Ancestral trait<\/strong>: A trait that has been inherited from a distant ancestor.<\/p>\n<p class=\"import-Normal\"><strong>Arboreal<\/strong>: A descriptor for an organism that spends most of its time in trees.<\/p>\n<p class=\"import-Normal\"><strong>Asian clade<\/strong>: A grouping that includes orangutang and their extinct relatives.<\/p>\n<p class=\"import-Normal\"><strong>Bilophodont<\/strong>: Molar pattern of cercopithecoid monkeys in which there are usually four cusps that are arranged in a square pattern and connected by two ridges.<\/p>\n<p class=\"import-Normal\"><strong>Bipedalism<\/strong>: Walking on two legs.<\/p>\n<p class=\"import-Normal\"><strong>Brachiation<\/strong>: A form of locomotion in which the organism swings below branches using the forelimbs.<\/p>\n<p class=\"import-Normal\"><strong>Bunodont<\/strong>: Low, rounded cusps on the cheek teeth.<\/p>\n<p class=\"import-Normal\"><strong>Canines<\/strong>: In most primates, these are the longest of the teeth, often conical in shape and used as a weapon against predators or others of their species.<\/p>\n<p class=\"import-Normal\"><strong>Cathemeral<\/strong>: Active throughout the 24-hour period.<\/p>\n<p class=\"import-Normal\"><strong>Clade<\/strong>: A grouping based on ancestral relationships; a branch of the evolutionary tree.<\/p>\n<p class=\"import-Normal\"><strong>Cusps<\/strong>: The bumps on the chewing surface of the premolars and molars, which can be quite sharp in some species.<\/p>\n<p class=\"import-Normal\"><strong>Dental formula<\/strong>: The number of each type of tooth in one quadrant of the mouth, written as number of incisors: canines: premolars: molars.<\/p>\n<p class=\"import-Normal\"><strong>Derived trait<\/strong>: A trait that has been recently modified, most helpful when assigning taxonomic classification.<\/p>\n<p class=\"import-Normal\"><strong>Diastema<\/strong>: A space between the teeth, usually for large canines to fit when the mouth is closed.<\/p>\n<p class=\"import-Normal\"><strong>Dichromatic<\/strong>: Being able to see only blues and greens.<\/p>\n<p class=\"import-Normal\"><strong>Diurnal<\/strong>: Active during the day.<\/p>\n<p class=\"import-Normal\"><strong>Dry nose<\/strong>: The nose and upper lip are separated and the upper lip can move independently; sometimes referred to as a \u201chairy\u201d or \u201cmobile\u201d upper lip.<\/p>\n<p class=\"import-Normal\"><strong>Ethnoprimatology<\/strong>: A subarea of anthropology that studies the complexities of human-primate relationships in the modern environment.<\/p>\n<p class=\"import-Normal\"><strong>Evolutionary trade-off<\/strong>: When an organism, which is limited in the time and energy it can put into aspects of its biology and behaviour, is shaped by natural selection to invest in one adaptation at the expense of another.<\/p>\n<p class=\"import-Normal\"><strong>Faunivorous<\/strong>: Having a diet consisting entirely of animal matter: insects, eggs, lizards, etc.<\/p>\n<p class=\"import-Normal\"><strong>Folivore<\/strong>: Having a diet consisting primarily of leaves.<\/p>\n<p class=\"import-Normal\"><strong>Fovea<\/strong>: A depressed area in the retina at the back of the eye containing a concentration of cells that allow one to focus on objects very close to one\u2019s face.<\/p>\n<p class=\"import-Normal\"><strong>Frugivore<\/strong>: Having a diet consisting primarily of fruit.<\/p>\n<p class=\"import-Normal\"><strong>Generalized trait<\/strong>: A trait that is useful for a wide range of tasks.<\/p>\n<p class=\"import-Normal\"><strong>Grade<\/strong>: A grouping based on overall similarity in lifestyle, appearance, and behaviour.<\/p>\n<p class=\"import-Normal\"><strong>Grooming claw<\/strong>: A claw present on the second pedal digit in strepsirrhines.<\/p>\n<p class=\"import-Normal\"><strong>Gummivore<\/strong>: Having a diet consisting primarily of gums and saps.<\/p>\n<p class=\"import-Normal\"><strong>Heterodont<\/strong>: Having different types of teeth.<\/p>\n<p class=\"import-Normal\"><strong>Homology<\/strong>: When two or more taxa share characteristics because they inherited them from a common ancestor.<\/p>\n<p class=\"import-Normal\"><strong>Hone<\/strong>: When primates sharpen their canines by wearing them on adjacent teeth.<\/p>\n<p class=\"import-Normal\"><strong>Incisors<\/strong>: The spatula-shaped teeth at the front of the mouth.<\/p>\n<p class=\"import-Normal\"><strong>Insectivore<\/strong>: Having a diet consisting primarily of insects.<\/p>\n<p class=\"import-Normal\"><strong>Ischial callosities<\/strong>: Modified seat bones of the pelvis that are flattened and over which calluses form; function as seat pads for sitting and resting atop branches.<\/p>\n<p class=\"import-Normal\"><strong>Knuckle-walking<\/strong>: A form of quadrupedal movement used by <em>Gorilla<\/em> and <em>Pan<\/em> when on the ground, wherein the front limbs are supported on the knuckles of the hands.<\/p>\n<p class=\"import-Normal\"><strong>Life history<\/strong>: Refers to an organism\u2019s pace of growth, reproduction, lifespan, etc.<\/p>\n<p class=\"import-Normal\"><strong>Locomotion<\/strong>: How an organism moves around.<\/p>\n<p class=\"import-Normal\"><strong>Male bimaturism<\/strong>: Refers to the alternative reproductive strategies in orangutans in which males can delay maturation, sometimes indefinitely, until a fully mature, \u201cflanged\u201d male disappears.<\/p>\n<p class=\"import-Normal\"><strong>Molars<\/strong>: The largest teeth at the back of the mouth; used for chewing. In primates, these teeth usually have between three and five cusps.<\/p>\n<p class=\"import-Normal\"><strong>Monochromatic<\/strong>: Being able to see only in shades of light to dark, no colour.<\/p>\n<p class=\"import-Normal\"><strong>Monomorphic<\/strong>: When males and females of a species do not exhibit significant sexual dimorphism.<\/p>\n<p class=\"import-Normal\"><strong>Natal coat<\/strong>: Refers to the contrasting fur colour of baby leaf monkeys compared to adults.<\/p>\n<p class=\"import-Normal\"><strong>Nocturnal<\/strong>: Active at night.<\/p>\n<p class=\"import-Normal\"><strong>Olecranon process<\/strong>: Bony projection at the elbow end of the ulna.<\/p>\n<p class=\"import-Normal\"><strong>Opposable thumb <\/strong>or <strong>opposable big toe<\/strong>: Having thumbs and toes that go in a different direction from the rest of the fingers, allows for grasping with hands and feet.<\/p>\n<p class=\"import-Normal\"><strong>Pentadactyly<\/strong>: Having five digits or fingers and toes.<\/p>\n<p class=\"import-Normal\"><strong>Polymorphic colour vision<\/strong>: A system in which individuals of a species vary in their abilities to see colour. In primates, it refers to males being dichromatic and females being either trichromatic or dichromatic.<\/p>\n<p class=\"import-Normal\"><strong>Postorbital bar<\/strong>: A bony ring that surrounds the eye socket, open at the back.<\/p>\n<p class=\"import-Normal\"><strong>Postorbital closure\/plate<\/strong>: A bony plate that provides protection to the side and back of the eye.<\/p>\n<p class=\"import-Normal\"><strong>Prehensile tail<\/strong>: A tail that is able to hold the full body weight of an organism, which often has a tactile pad on the underside of the tip for improved grip.<\/p>\n<p class=\"import-Normal\"><strong>Premolars<\/strong>: Smaller than the molars, used for chewing. In primates, these teeth usually have one or two cusps.<\/p>\n<p class=\"import-Normal\"><strong>Quadrupedalism<\/strong>: Moving around on all fours.<\/p>\n<p class=\"import-Normal\"><strong>Rhinariums<\/strong>: Wet noses; resulting from naked skin of the nose which connects to the upper lip and smell-sensitive structures along the roof of the mouth.<\/p>\n<p class=\"import-Normal\"><strong>Sagittal crest<\/strong>: A bony ridge along the top\/middle of the skull, used for attachment of chewing muscles.<\/p>\n<p class=\"import-Normal\"><strong>Scent marking<\/strong>: The behaviour of rubbing scent glands or urine onto objects as a way of communicating with others.<\/p>\n<p class=\"import-Normal\"><strong>Semi-brachiation<\/strong>: A form of locomotion in which an organism swings below branches using a combination of forelimbs and prehensile tail.<\/p>\n<p class=\"import-Normal\"><strong>Sexually dimorphic<\/strong>: When a species exhibits sex differences in morphology, behaviour, hormones, and\/or colouration.<\/p>\n<p class=\"import-Normal\"><strong>Shearing crests<\/strong>: Sharpened ridges that connect cusps on a bilophodont molar.<\/p>\n<p class=\"import-Normal\"><strong>Specialized trait<\/strong>: A trait that has been modified for a specific purpose.<\/p>\n<p class=\"import-Normal\"><strong>Styloid process of ulna<\/strong>: A bony projection of the ulna at the end near the wrist.<\/p>\n<p class=\"import-Normal\"><strong>Tactile pads<\/strong>: Sensitive skin at the fingertips for sense of touch. Animals with a prehensile tail have a tactile pad on the underside of the tail as well.<\/p>\n<p class=\"import-Normal\"><strong>Tapetum lucidum<\/strong>: Reflecting layer at the back of the eye that magnifies light.<\/p>\n<p class=\"import-Normal\"><strong>Terrestrial<\/strong>: A descriptor for an organism that spends most of its time on the ground.<\/p>\n<p class=\"import-Normal\"><strong>Tetrachromatic<\/strong>: Having the ability to see reds, yellows, blues, greens, and ultraviolet.<\/p>\n<p class=\"import-Normal\"><strong>Tooth comb<\/strong> or <strong>dental comb<\/strong>: A trait of the front, lower teeth of strepsirrhines in which, typically, the four incisors and canines are long and thin and protrude outward.<\/p>\n<p class=\"import-Normal\"><strong>Trichromatic colour vision<\/strong>: Being able to distinguish yellows and reds in addition to blues and greens.<\/p>\n<p class=\"import-Normal\"><strong>Vertical clinging and leaping<\/strong>: A locomotor pattern in which animals are oriented upright while clinging to vertical branches, push off with hind legs, and land oriented upright on another vertical branch.<\/p>\n<p class=\"import-Normal\"><strong>Y-5 molar<\/strong>: Molar cusp pattern in which five molar cusps are separated by a \u201cY\u201d-shaped groove pattern.<\/p>\n<h2 class=\"import-Normal\">For Further Exploration<\/h2>\n<p class=\"import-Normal\"><a href=\"https:\/\/animaldiversity.org\/accounts\/Primates\/specimens\/\" target=\"_blank\">Animal Diversity Web<\/a>. This website is hosted by the Zoology Department at the University of Michigan. It has photographs of skulls, teeth, hands, arms, and feet of many primate species.<\/p>\n<p class=\"import-Normal\"><a href=\"https:\/\/www.eskeletons.org\" target=\"_blank\">eSkeletons<\/a>. This website is hosted by the Department of Anthropology at University of Texas, Austin. It is an interactive website where you can compare specific bones from different species of primates.<\/p>\n<p class=\"import-Normal\">Fleagle, John G. 2013. <em>Primate Adaptation and Evolution<\/em>. Third edition. San Diego: Academic Press.<\/p>\n<p class=\"import-Normal\">Fuentes, Agust\u00edn, and Kimberley J. Hockings. 2010. \u201cThe Ethnoprimatological Approach in Primatology.\u201d <em>American Journal of Primatology<\/em> 72 (10): 841\u2013847.<\/p>\n<p class=\"import-Normal\">Rowe, Noel. 1996. <em>Pictorial Guide to the Living Primates<\/em>. Charlestown, RI: Pogonias Press.<\/p>\n<p class=\"import-Normal\">Whitehead, Paul F., William K. Sacco, and Susan B. Hochgraf. 2005. <em>A Photographic Atlas for Physical Anthropology<\/em>. Englewood, CO: Morton Publishing.<\/p>\n<h2>References<\/h2>\n<p class=\"import-Normal\">Balolia, Katharine L., Christophe Soligo, and Bernard Wood. 2017. \u201cSagittal Crest Formation in Great Apes and Gibbons.\u201d <em>Journal of Anatomy<\/em> 230 (6): 820\u2013832.<\/p>\n<p class=\"import-Normal\">Bininda-Emonds, Olaf R., Marcel Cardillo, Kate E. Jones, Ross D. E. MacPhee, Robin M. D. Beck, Richard Grenyer, Samantha A. Price, Rutger A. Vos, John L. Gittleman, and Andy Purvis. 2007. \u201cThe Delayed Rise of Present-Day Mammals.\u201d <em>Nature<\/em> 446 (7135): 507\u2013512.<\/p>\n<p class=\"import-Normal\">Burton, Michael L., Carmella C. Moore, John W. M. Whiting, A. Kimball Romney, David F. Aberle, Juan A. Barcelo, Malcolm M. Dow, et al. 1996. \u201cRegions Based on Social Structure.\u201d <em>Current Anthropology<\/em> 37 (1): 87\u2013123.<\/p>\n<p class=\"import-Normal\">Chivers, David J., and C. M. Hladik. 1980. \u201cMorphology of the Gastrointestinal Tract in Primates: Comparisons with Other Mammals in Relation to Diet.\u201d <em>Journal of Morphology<\/em> 166 (3): 337\u2013386.<\/p>\n<p class=\"import-Normal\">Clutton-Brock, T. H., and Paul H. Harvey. 1980. \u201cPrimates, Brains, and Ecology.\u201d <em>Journal of Zoology<\/em> 190 (3): 309\u2013323.<\/p>\n<p class=\"import-Normal\">Dunbar, Robin I. M. 1998. \u201cThe Social Brain Hypothesis.\u201d <em>Evolutionary Anthropology<\/em> 6 (5): 178\u2013190.<\/p>\n<p class=\"import-Normal\">Ebersberger, Ingo, Dirk Metzler, Carsten Schwarz, and Svante P\u00e4\u00e4bo. 2002. \u201cGenomewide Comparison of DNA Sequences Between Humans and Chimpanzees.\u201d <em>American Journal of Human Genetics<\/em> 70 (6): 1490\u20131497.<\/p>\n<p class=\"import-Normal\">Jameson, Natalie M., Zhuo-Cheng Hou, Kirstin N. Sterner, Amy Weckle, Morris Goodman, Michael E. Steiper, and Derek E. Wildman. 2011. \u201cGenomic Data Reject the Hypothesis of a Prosimian Primate Clade.\u201d <em>Journal of Human Evolution<\/em> 61 (3): 295\u2013305.<\/p>\n<p class=\"import-Normal\">Kawamura, Shoji, Chihiro Hiramatsu, Amanda D. Melin, Colleen M. Schaffner, Filippo Aureli, and Linda M. Fedigan. 2012. \u201cPolymorphic Color Vision in Primates: Evolutionary Considerations.\u201d In <em>Post-Genome Biology of Primates<\/em>, edited by H. Irai, H. Imai, and Y. Go, 93\u2013120. Tokyo: Springer.<\/p>\n<p class=\"import-Normal\">Matsui, Atsushi, Felix Rakotondraparany, Isao Munechika, Masami Hasegawa, and Satoshi Horai. 2009. \u201cMolecular Phylogeny and Evolution of Prosimians Based on Complete Sequences of Mitochondrial DNAs.\u201d <em>Gene<\/em> 441 (1\u20132): 53\u201366.<\/p>\n<p class=\"import-Normal\">Nater, Alexander, Maja P. Mattle-Greminger, Anton Nurcahyo, Matthew G. Nowak, Marc de Manuel, Tariq Desai, Colin Groves, et al. 2017. \u201cMorphometric, Behavioral, and Genomic Evidence for a New Orangutan Species.\u201d <em>Current Biology<\/em> 27 (22): 3487\u20133498.<\/p>\n<p class=\"import-Normal\">Pozzi, Luca, Jason A. Hodgson, Andrew S. Burrell, Kirstin N. Sterner, Ryan L. Raaum, and Todd R. Disotell. 2014. \u201cPrimate Phylogenetic Relationships and Divergence Dates Inferred from Complete Mitochondrial Genomes.\u201d <em>Molecular Phylogenetics and Evolution<\/em> 75: 165\u2013183.<\/p>\n<p class=\"import-Normal\">Remis, Melissa J. 1997. \u201cWestern Lowland Gorillas (<em>Gorilla gorilla gorilla<\/em>) as Seasonal Frugivores: Use of Variable Resources.\u201d <em>American Journal of Primatology<\/em> 43 (2): 87\u2013109.<\/p>\n<p class=\"import-Normal\">Richmond, Brian G., David R. Begun, and David S. Strait. 2001. \u201cOrigin of Human Bipedalism: The Knuckle\u2010Walking Hypothesis Revisited.\u201d <em>American<\/em> <em>Journal of Physical Anthropology<\/em> 116 (S33): 70\u2013105.<\/p>\n<p class=\"import-Normal\">Robson, Shannen L., Carel P. van Schaik, and Kristen Hawkes. 2006. \u201cThe Derived Features of Human Life History.\u201d In <em>The Evolution of Human Life History, edited by Kristen Hawkes and Richard R. Paine, <\/em>17\u201344. Santa Fe: SAR Press.<\/p>\n<p class=\"import-Normal\">Scally, Aylwyn, Julien Y. Dutheil, LaDeana W. Hillier, Gregory E. Jordan, Ian Goodhead, Javier Herrero, Asger Hobolth, et al. 2012. \u201cInsights into Hominid Evolution from the Gorilla Genome Sequence.\u201d <em>Nature<\/em> 483 (7388): 169\u2013175.<\/p>\n<p class=\"import-Normal\">Schneider, Horacio, and Iracilda Sampaio. 2015. \u201cThe Systematics and Evolution of New World Primates: A Review.\u201d <em>Molecular Phylogenetics and Evolution<\/em> 82 (B): 348\u2013357.<\/p>\n<p class=\"import-Normal\">Setchell, Joanna M., Phyllis C. Lee, E. Jean Wickings, and Alan F. Dixson. 2001. \u201cGrowth and Ontogeny of Sexual Size Dimorphism in the Mandrill (<em>Mandrillus sphinx<\/em>).\u201d <em>American Journal of Physical Anthropology<\/em> 115 (4): 349\u2013360.<\/p>\n<p class=\"import-Normal\">Utami, Sri Suci, Beno\u00eet Goossens, Michael W. Bruford, Jan R. de Ruiter, and Jan A. R. A. M. van Hooff. 2002. \u201cMale Bimaturism and Reproductive Success in Sumatran Orang-utans.\u201d <em>Behavioral Ecology<\/em> 13 (5): 643\u2013652.<\/p>\n<p class=\"import-Normal\">Vasey, Natalie. 2006. \u201cImpact of Seasonality and Reproduction on Social Structure, Ranging Patterns, and Fission\u2013Fusion Social Organization in Red Ruffed Lemurs.\u201d In <em>Lemurs: Ecology and Adaptation<\/em>, edited by Lisa Gould and Michelle L. Sauther, 275\u2013304. New York: Springer.<\/p>\n<p class=\"import-Normal\">Wright, Patricia C. 1999. \u201cLemur Traits and Madagascar Ecology: Coping with an Island Environment.\u201d <em>American Journal of Physical Anthropology<\/em> 110 (S29): 31\u201372.<\/p>\n<h2>Acknowledgements<\/h2>\n<p class=\"import-Normal\">The author would very much like to thank the editors for the opportunity to contribute to this textbook, along with anonymous reviewers who provided useful feedback on earlier drafts of this chapter. She would particularly like to thank Karin Enstam Jaffe for her support and encouragement during the writing of this chapter and its revision. Most of all, the author would like to thank all of the Introduction to Biological Anthropology students that she has had over the years who have listened to her lecture endlessly on these animals that she finds so fascinating and who have helped her to hone her pedagogy in a field that she loves.<\/p>\n<\/div>\n<\/div>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1695_1871\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1695_1871\"><div tabindex=\"-1\"><div class=\"__UNKNOWN__\">\n<div class=\"textbox\">\n<h6>Student contributors to this chapter: Angela Durastanti, Bryce Muller, Gabriel Barr, Maisie Babbington-Bolduc<\/h6>\n<p>Learn more about <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/about-the-authors\/\">authors and editors<\/a>,<a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/student-contributors\/\"> Hess' student contributions<\/a>, and <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/versioning-history\/\">versioning history<\/a>.<\/p>\n<\/div>\n<div class=\"textbox textbox--learning-objectives\">\n<header class=\"textbox__header\">\n<h2 class=\"textbox__title\">Learning Objectives<\/h2>\n<\/header>\n<div class=\"textbox__content\">\n<ul>\n<li><span style=\"color: #000000\">Understand what is meant by \u201cderived\u201d and \u201cancestral\u201d traits and why this is relevant for understanding early hominin evolution.<\/span><\/li>\n<li><span style=\"color: #000000\">Understand changing paleoclimates and paleoenvironments as potential factors influencing early hominin adaptations.<\/span><\/li>\n<li><span style=\"color: #000000\">Describe the anatomical changes associated with bipedalism and dentition in early hominins, as well as their implications..<\/span><\/li>\n<li><span style=\"color: #000000\">Describe early hominin genera and species, including their currently understood dates and geographic expanses.<\/span><\/li>\n<li><span style=\"color: #000000\">Describe the earliest stone tool techno-complexes and their impact on the transition from early hominins to our genus.<\/span><\/li>\n<\/ul>\n<\/div>\n<\/div>\n<h2 class=\"__UNKNOWN__\"><span style=\"color: #000000\">Defining Hominins<\/span><\/h2>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">It is through our study of our hominin ancestors and relatives that we are exposed to a world of \u201cmight have beens\u201d: of other paths not taken by our species, other ways of being human. But to better understand these different evolutionary trajectories, we must first define the terms we are using. If an imaginary line were drawn between ourselves and our closest relatives, the great apes, <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1291\">bipedalism<\/a><\/strong> (or habitually walking upright on two feet) is where that line would be. <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1326\">Hominin<\/a><\/strong>, then, means everyone on \u201cour\u201d side of the line: humans and all of our extinct bipedal ancestors and relatives since our divergence from the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1327\">last common ancestor (LCA)<\/a> <\/strong>we share with chimpanzees.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Historic interpretations of our evolution, prior to our finding of early hominin <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1328\">fossils<\/a><\/strong>, varied. Debates in the mid-1800s regarding hominin origins focused on two key issues:<\/span><\/p>\n<ul>\n<li class=\"import-Normal\" style=\"background-color: transparent;text-align: left;text-indent: 0pt\"><span style=\"color: #000000\">Where did we evolve?<\/span><\/li>\n<li class=\"import-Normal\" style=\"background-color: transparent;text-align: left;text-indent: 0pt\"><span style=\"color: #000000\">Which traits evolved first?<\/span><\/li>\n<\/ul>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Within this conversation, naturalists and early <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1329\">paleoanthropologists<\/a><\/strong> (people who study human evolution) speculated about which human traits came first. These included the evolution of a big brain (<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1330\">encephalization<\/a><\/strong>), the evolution of the way in which we move about on two legs (bipedalism), and the evolution of our flat faces and small teeth (indications of dietary change). Original hypotheses suggested that, in order to be motivated to change diet and move about in a bipedal fashion, the large brain needed to have evolved first, as is seen in the fossil species mentioned above.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">However, we now know that bipedal locomotion is one of the first things that evolved in our lineage, with early relatives having more apelike dentition and small brain sizes. While brain size expansion is seen primarily in our genus, <em>Homo<\/em>, earlier hominin brain sizes were highly variable between and within taxa, from 300 cc (cranial capacity, cm<sup>3<\/sup>), estimated in <em>Ardipithecus<\/em>, to 550 cc, estimated in <em>Paranthropus boisei<\/em>. The lower estimates are well within the range of variation of nonhuman extant great apes. In addition, body size variability also plays a role in the interpretation of whether brain size could be considered large or small for a particular species or specimen. In this chapter, we will tease out the details of early hominin evolution in terms of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1331\">morphology<\/a><\/strong> (i.e. the study of the form, size, or shape of things; in this case, skeletal parts).<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">We also know that early human evolution occurred in a very complicated fashion. There were multiple species (multiple genera) that featured diversity in their diets and locomotion. Specimens have been found all along the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1332\"><strong>East African Rift System<\/strong>(EARS)<\/a>; that is, in Ethiopia, Kenya, Tanzania, and Malawi; see Figure 10.1), in limestone caves in South Africa, and in Chad. Dates of these early relatives range from around 7 million years ago (mya) to around 1 mya, overlapping temporally with members of our genus, <em>Homo<\/em>.<\/span><\/p>\n<p>&nbsp;<\/p>\n<figure style=\"width: 610px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2023\/06\/image38.png\" alt=\"Patchy green mountain alongside a deep sandy valley in East Africa.\" width=\"610\" height=\"277\" \/><figcaption class=\"wp-caption-text\"><span style=\"color: #000000\">Figure 10.1: East African Rift System (EARS). Credit: <a href=\"https:\/\/www.flickr.com\/photos\/ninara\/8624605781\/in\/photolist-x2yH7-x2yHe-VfVWuD-e98mPF-SzzjsU-2bsBZhC-2hHec7m-xtJ7Ez-NXnXvh-7Yg3uo-2cS3FgG-2hjo1Dc-2hjGoTS-nnumi8-82U66W-dMNn7B-8jdVbd-NWDg8-NW6fj-ebhx5w-bkFv1G-Ct5ZD-5JQk8A-y6TgAc-x9k6oe-2ebLTDC-WcPMnJ-2ekh6CS-Cu3LH-xNHDFK-9RUsZi-94jVt4-P46uiB-QFyjyE-crU8N7-5JLJKV-2ekSgk8-5JL454-2cPgZrF-2bHfQZu-dMTVPN-6yUbeN-jzMicQ-48XjU9-2etR2Ze-Styrvw-crU7V7-2wakq3-crU6Z1-2etR2XR\/\" target=\"_blank\">IMG_1696 Great Rift Valley<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/ninara\/\" target=\"_blank\">Ninara<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/\" target=\"_blank\">CC BY 2.0 License<\/a>.<\/span><\/figcaption><\/figure>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Yet there is still so much to understand. Modern debates now look at the relatedness of these species to us and to one another, and they consider which of these species were able to make and use tools. As a result, every <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1333\">site<\/a><\/strong> discovery in the patchy hominin fossil record tells us more about our evolution. In addition, recent scientific techniques (not available even ten years ago) provide new insights into the diets, environments, and lifestyles of these ancient relatives.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">In the past, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1335\"><strong>taxonomy<\/strong><\/a> was primarily based on morphology. Today it is tied to known relationships based on molecular <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1336\">phylogeny<\/a><\/strong> (e.g., based on DNA) or a combination of the two. This is complicated when applied to living <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1334\">taxa<\/a><\/strong>, but becomes much more difficult when we try to categorize ancestor-descendant relationships for long-extinct species whose molecular information is no longer preserved. We therefore find ourselves falling back on morphological comparisons, often of teeth and partially fossilized skeletal material.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">It is here that we turn to the related concepts of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1337\">cladistics<\/a> <\/strong>and <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1338\">phylogenetics<\/a><\/strong><strong>. <\/strong>Cladistics groups organisms according to their last common ancestors based on shared <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1254\">derived traits<\/a><\/strong>. In the case of early hominins, these are often morphological traits that differ from those seen in earlier populations. These new or modified traits provide evidence of evolutionary relationships, and organisms with the same derived traits are grouped in the same <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1249\">clade<\/a> <\/strong>(Figure 10.2). For example, if we use feathers as a trait, we can group pigeons and ostriches into the clade of birds. In this chapter, we will examine the grouping of the Robust Australopithecines, whose cranial and dental features differ from those of earlier hominins, and therefore are considered derived.<\/span><\/p>\n<figure style=\"width: 708px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image48.png\" alt=\"Phylogenetic tree shows clades and non clade groupings.\" width=\"708\" height=\"192\" \/><figcaption class=\"wp-caption-text\"><span style=\"color: #000000\">Figure 10.2: Clades refer to groups of species or taxa that share a common ancestor. In <span class=\"ILfuVd\" lang=\"en\"><span class=\"hgKElc\">a phylogeny, a clade is a complete group of lineages, including their last common ancestor. Groupings that do not include a common ancestor and <em>all<\/em> of its descendants are not clades. <\/span><\/span>Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/chapter-9-early-hominins-2\/\" target=\"_blank\">Clades (Figure 9.2)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Katie Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<br \/><\/span><\/figcaption><\/figure>\n<div class=\"textbox shaded\">\n<h2 class=\"import-Normal\"><span style=\"color: #000000\">Dig Deeper: Problems Defining Hominin Species<\/span><\/h2>\n<p class=\"import-Normal\"><span style=\"color: #000000\">It is worth noting that species designations for early hominin specimens are often highly contested. This is due to the fragmentary nature of the fossil record, the large timescale (millions of years) with which paleoanthropologists need to work, and the difficulty in evaluating whether morphological differences and similarities are due to meaningful phylogenetic or biological differences or subtle differences\/variation in niche occupation or time. In other words, do morphological differences really indicate different species? How would classifying species in the paleoanthropological record compare with classifying living species today, for whom we can sequence genomes and observe lifestyles?<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">There are also broader philosophical differences among researchers when it comes to paleo-species designations. Some scientists, known as \u201c<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1339\">lumpers<\/a><\/strong>,\u201d argue that large variability is expected among multiple populations in a given species over time. These researchers will therefore prefer to \u201clump\u201d specimens of subtle differences into single taxa. Others, known as \u201c<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1340\">splitters<\/a><\/strong>,\u201d argue that species variability can be measured and that even subtle differences can imply differences in niche occupation that are extreme enough to mirror modern species differences. In general, splitters would consider geographic differences among populations as meaning that a species is <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1341\">polytypic<\/a><\/strong>. This is worth keeping in mind when learning about why species designations may be contested.<\/span><\/p>\n<figure style=\"width: 520px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image8.jpg\" alt=\"A graph shows a curved line depicting changes in morphology among two species over time.\" width=\"520\" height=\"292\" \/><figcaption class=\"wp-caption-text\"><span style=\"color: #000000\">Figure 10.3: This graph demonstrates the concept of a chronospecies, where one species (Species A) \u201cevolves\u201d into another (Species B). Credit: Chronospecies original to Explorations: An Open Invitation to Biological Anthropology, 2nd edition by Kerryn Warren is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<br \/><\/span><\/figcaption><\/figure>\n<p class=\"import-Normal\"><span style=\"color: #000000\">This further plays a role in evaluating ancestry. Debates over which species \u201cgave rise\u201d to which continue to this day. It is common to try to create \u201clineages\u201d of species to determine when one species evolved into another over time. We refer to these as <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1342\">chronospecies<\/a><\/strong> (Figure 10.3). Constructed hominin phylogenetic trees are routinely variable, changing with new specimen discoveries, new techniques for evaluating and comparing species, and, some have argued, nationalist or biased interpretations of the record. More recently, some researchers have shifted away from \u201ctreelike\u201d models of ancestry toward more nuanced metaphors such as the \u201cbraided stream,\u201d where some levels of interbreeding among species and populations are seen as natural processes of evolution.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Finally, it is worth considering the process of fossil discovery and publication. Some fossils are easily diagnostic to a species level and allow for easy and accurate interpretation. Some, however, are more controversial. This could be because they do not easily preserve or are incomplete, making it difficult to compare and place within a specific species (e.g., a fossil of a patella or knee bone). Researchers often need to make several important claims when announcing or publishing a find: a secure date (if possible), clear association with other finds, and an adequate comparison among multiple species (both extant and fossil). Therefore, it is not uncommon that an important find was made years before it is scientifically published.<\/span><\/p>\n<\/div>\n<h2 class=\"import-Normal\"><span style=\"color: #000000\">Paleoenvironment and Hominin Evolution<\/span><\/h2>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">There is no doubt that one of the major selective pressures in hominin evolution is the environment. Large-scale changes in global and regional climate, as well as alterations to the environment, are thought to be linked to all hominin diversification, dispersal, and extinction (Maslin et al. 2014). Environmental reconstructions often use modern analogues. Let us take, for instance, the hippopotamus. It is an animal that thrives in environments that have abundant water to keep its skin cool and moist. If the environment for some reason becomes drier, it is expected that hippopotamus populations will reduce. If a drier environment becomes wetter, it is possible that hippopotamus populations may be attracted to the new environment and thrive. Such instances have occurred multiple times in the past, and the bones of some <strong style=\"background-color: transparent\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1345\">fauna<\/a><\/strong> (i.e., animals, like the hippopotamus) that are sensitive to these changes give us insights into these events.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Yet reconstructing a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1343\">paleoenvironment<\/a><\/strong> relies on a range of techniques, which vary depending on whether research interests focus on local changes or more global environmental changes\/reconstructions. For local environments (such as a single site or region), comparing the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1344\">faunal assemblages<\/a> <\/strong>(collections of fossils of animals found at a site) with animals found in certain modern environments allows us to determine if past environments mirror current ones in the region. Changes in the faunal assemblages, as well as when they occur and how they occur, tell us about past environmental changes. Other techniques are also useful in this regard. Chemical analyses, for instance, can reveal the diets of individual fauna, providing clues as to the relative wetness or dryness of their environment (e.g., nitrogen <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1138\">isotopes<\/a><\/strong>; Kingston and Harrison 2007).<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Global climatic changes in the distant past, which fluctuated between being colder and drier and warmer and wetter on average, would have global implications for environmental change (Figure 10.4). These can be studied by comparing marine core and terrestrial soil data across multiple sites. These techniques are based on chemical analysis, such as examination of the nitrogen and oxygen isotopes in shells and sediments. Similarly, analyzing pollen grains shows which kinds of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1347\">flora<\/a><\/strong> survived in an environment at a specific time period. There are multiple lines of evidence that allow us to visualize global climate trends over millions of years (although it should be noted that the direction and extent of these changes could differ by geographic region).<\/span><\/p>\n<p>&nbsp;<\/p>\n<figure style=\"width: 649px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image12-1-1.png\" alt=\"Chart shows cyclical carbon dioxide levels from 800,000 years ago until today.\" width=\"649\" height=\"406\" \/><figcaption class=\"wp-caption-text\"><span style=\"color: #000000\">Figure 10.4: This graph, based on the comparison of atmospheric samples contained in ice cores and more recent direct measurements, illustrates how atmospheric CO\u2082 has fluctuated over time and increased sharply since the Industrial Revolution. The graph also shows that since 800,000ya (and before) atmospheric CO\u2082 has never exceeded 300 parts per million (ppm). In 1950 it was 310ppm. Today atmospheric CO\u2082 has spiked to over 410 ppm. Credit: <a href=\"https:\/\/climate.nasa.gov\/evidence\/\" target=\"_blank\">CO\u2082 increase since the Industrial Revolution<\/a> by <a href=\"https:\/\/www.nasa.gov\/\" target=\"_blank\">NASA<\/a> is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\" target=\"_blank\">public domain<\/a> and is used within <a href=\"https:\/\/www.nasa.gov\/multimedia\/guidelines\/index.html\" target=\"_blank\">NASA guidelines on re-use<\/a>. Original from Luthi, D., et al.. 2008; Etheridge, D.M., et al. 2010; Vostok ice core data\/J.R. Petit et al.; NOAA Mauna Loa CO<a href=\"https:\/\/climate.nasa.gov\/evidence\/\" target=\"_blank\">\u2082<\/a> record..<\/span><\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Both local and global climatic\/environmental changes have been used to understand factors affecting our evolution (DeHeinzelin et al. 1999; Kingston 2007). Environmental change acts as an important factor regarding the onset of several important hominin traits seen in early hominins and discussed in this chapter. Namely, the environment has been interpreted as the following:<\/span><\/p>\n<ul>\n<li class=\"import-Normal\" style=\"background-color: transparent;text-align: left;text-indent: 0pt\"><span style=\"color: #000000\">the driving force behind the evolution of bipedalism,<\/span><\/li>\n<li class=\"import-Normal\" style=\"background-color: transparent;text-align: left;text-indent: 0pt\"><span style=\"color: #000000\">the reason for change and variation in early hominin diets, and<\/span><\/li>\n<li class=\"import-Normal\" style=\"background-color: transparent;text-align: left;text-indent: 0pt\"><span style=\"color: #000000\">the diversification of multiple early hominin species.<\/span><\/li>\n<\/ul>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">There are numerous hypotheses regarding how climate has driven and continues to drive human evolution. Here, we will focus on just three popular hypotheses.<\/span><\/p>\n<h3 class=\"import-Normal\"><span style=\"color: #000000\"><strong>Savannah Hypothesis (or Aridity Hypothesis)<\/strong><\/span><\/h3>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>The hypothesis:<\/strong> This popular theory suggests that the expansion of the savannah (or less densely forested, drier environments) forced early hominins from an <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1348\">arboreal<\/a><\/strong> lifestyle (one living in trees) to a terrestrial one where bipedalism was a more efficient form of locomotion (Figure 10.5). It was first proposed by Darwin (1871) and supported by anthropologists like Raymond Dart (1925). However, this idea was supported by little fossil or paleoenvironmental evidence and was later refined as the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1350\">Aridity Hypothesis<\/a><\/strong>. This hypothesis states that the long-term <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1349\">aridification<\/a> <\/strong>and, thereby, expansion of savannah biomes were drivers in diversification in early hominin evolution (deMenocal 2004; deMenocal and Bloemendal 1995). It advocates for periods of accelerated aridification leading to early hominin speciation events.<\/span><\/p>\n<p>&nbsp;<\/p>\n<figure style=\"width: 647px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image46.png\" alt=\"Photograph showing a dry, open savannah environment.\" width=\"647\" height=\"486\" \/><figcaption class=\"wp-caption-text\"><span style=\"color: #000000\">Figure 10.5: The African savannah grew during early hominin evolution. This may have forced early hominins from an arboreal lifestyle to a terrestrial one, where bipedalism was a more efficient form of locomotion. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:African_savannah_@_Masai_Mara_(21308330314).jpg\" target=\"_blank\">African savannah @ Masai Mara (21308330314)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/132394214@N04\" target=\"_blank\">Leo Li<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/legalcode\" target=\"_blank\">CC BY 2.0 License<\/a>.<br \/><\/span><\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>The evidence:<\/strong> While early bipedal hominins are often associated with wetter, more closed environments (i.e., not the Savannah Hypothesis), both marine and terrestrial records seem to support general cooling, drying conditions, with isotopic records indicating an increase in grasslands (i.e., colder and wetter climatic conditions) between 8 mya and 6 mya across the African continent (Cerling et al. 2011). This can be contrasted with later climatic changes derived from aeolian dust records (sediments transported to the site of interest by wind), which demonstrate increases in seasonal rainfall between 3 mya and 2.6 mya, 1.8 mya and 1.6 mya, and 1.2 mya and 0.8 mya (deMenocal 2004; deMenocal and Bloemendal 1995).<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Interpretation(s):<\/strong> Despite a relatively scarce early hominin record, it is clear that two important factors occur around the time period in which we see increasing aridity. The first factor is the diversification of taxa, where high morphological variation between specimens has led to the naming of multiple hominin genera and species. The second factor is the observation that the earliest hominin fossils appear to have traits associated with bipedalism and are dated to around the drying period (as based on isotopic records). Some have argued that it is more accurately a combination of bipedalism and arboreal locomotion, which will be discussed later. However, the local environments in which these early specimens are found (as based on the faunal assemblages) do not appear to have been dry.<\/span><\/p>\n<h3 class=\"import-Normal\"><span style=\"color: #000000\"><strong>Turnover Pulse Hypothesis<\/strong><\/span><\/h3>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>The hypothesis:<\/strong> In 1985, paleontologist Elisabeth Vbra noticed that in periods of extreme and rapid climate change, <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1354\">ungulates<\/a><\/strong> (hoofed mammals of various kinds) that had generalized diets fared better than those with specialized diets (Vrba 1988, 1998). <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1352\">Specialist<\/a><\/strong> eaters faced extinction at greater rates than their <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1351\">generalist<\/a> <\/strong>counterparts because they were unable to adapt to new environments (Vrba 2000). Thus, periods with extreme climate change would be associated with high <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1353\">faunal turnover<\/a><\/strong>: that is, the extinction of many species and the speciation, diversification, and migration of many others to occupy various niches.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>The evidence:<\/strong> The onset of the<strong> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1391\">Quaternary Ice Age<\/a><\/strong>, between 2.5 mya and 3 mya, brought extreme global, cyclical <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1355\">interglacial<\/a><\/strong> and <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1356\">glacial<\/a><\/strong> periods (warmer, wetter periods with less ice at the poles, and colder, drier periods with more ice near the poles). Faunal evidence from the Turkana basin in East Africa indicates multiple instances of faunal turnover and extinction events, in which global climatic change resulted in changes from closed\/forested to open\/grassier habitats at single sites (Behrensmeyer et al. 1997; Bobe and Behrensmeyer 2004). Similarly, work in the Cape Floristic Belt of South Africa shows that extreme changes in climate play a role in extinction and migration in ungulates. While this theory was originally developed for ungulates, its proponents have argued that it can be applied to hominins as well. However, the link between climate and speciation is only vaguely understood (Faith and Behrensmeyer 2013).<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Interpretation(s):<\/strong> While the evidence of rapid faunal turnover among ungulates during this time period appears clear, there is still some debate around its usefulness as applied to the paleoanthropological record. Specialist hominin species do appear to exist for long periods of time during this time period, yet it is also true that <em>Homo<\/em>, a generalist genus with a varied and adaptable diet, ultimately survives the majority of these fluctuations, and the specialists appear to go extinct.<\/span><\/p>\n<h3 class=\"import-Normal\"><span style=\"color: #000000\"><strong>Variability Selection Hypothesis<\/strong><\/span><\/h3>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>The hypothesis: <\/strong>This hypothesis was first articulated by paleoanthropologist Richard Potts (1998). It links the high amount of climatic variability over the last 7 million years to both behavioural and morphological changes. Unlike previous notions, this hypothesis states that hominin evolution does not respond to habitat-specific changes or to specific aridity or moisture trends. Instead, long-term environmental unpredictability over time and space influenced morphological and behavioural adaptations that would help hominins survive, regardless of environmental context (Potts 1998, 2013). The Variability Selection Hypothesis states that hominin groups would experience varying degrees of natural selection due to continually changing environments and potential group isolation. This would allow certain groups to develop genetic combinations that would increase their ability to survive in shifting environments. These populations would then have a genetic advantage over others that were forced into habitat-specific adaptations (Potts 2013).<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>The evidence:<\/strong> The evidence for this theory is similar to that for the Turnover Pulse Hypothesis: large climatic variability and higher survivability of generalists versus specialists. However, this hypothesis accommodates for larger time-scales of extinction and survival events.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Interpretation(s):<\/strong> In this way, the Variability Selection Hypothesis allows for a more flexible interpretation of the evolution of bipedalism in hominins and a more fluid interpretation of the Turnover Pulse Hypothesis, where species turnover is meant to be more rapid. In some ways, this hypothesis accommodates both environmental data and our interpretations of an evolution toward greater variability among species and the survivability of generalists.<\/span><\/p>\n<h2 class=\"import-Normal\"><span style=\"color: #000000\">Derived Adaptations: Bipedalism<br \/>\n<\/span><\/h2>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">The unique form of locomotion exhibited by modern humans, called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1357\">obligate bipedalism<\/a><\/strong>, is important in distinguishing our species from the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1358\">extant<\/a><\/strong> (living) great apes. The ability to walk habitually upright is thus considered one of the defining attributes of the hominin lineage. We also differ from other animals that walk bipedally (such as kangaroos) in that we do not have a tail to balance us as we move.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">The origin of bipedalism in hominins has been debated in paleoanthropology, but at present there are two main theories:<\/span><\/p>\n<ol>\n<li class=\"import-Normal\" style=\"background-color: transparent;text-align: left;text-indent: 0pt\"><span style=\"color: #000000\">early hominins initially lived in trees, but increasingly started living on the ground, so we were a product of an arboreal last common ancestor (LCA) or,<\/span><\/li>\n<li class=\"import-Normal\" style=\"background-color: transparent;text-align: left;text-indent: 0pt\"><span style=\"color: #000000\">our LCA was a terrestrial quadrupedal knuckle-walking species, more similar to extant chimpanzees.<\/span><\/li>\n<\/ol>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Most research supports the first theory of an arboreal LCA based on skeletal morphology of early hominin genera that demonstrate adaptations for climbing but not for knuckle-walking. This would mean that both humans and chimpanzees can be considered \u201cderived\u201d in terms of locomotion since chimpanzees would have independently evolved knuckle-walking.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">There are many current ideas regarding selective pressures that would lead to early hominins adapting upright posture and locomotion. Many of these selective pressures, as we have seen in the previous section, coincide with a shift in environmental conditions, supported by paleoenvironmental data. In general, however, it appears that, like extant great apes, early hominins thrived in forested regions with dense tree coverage, which would indicate an arboreal lifestyle. As the environmental conditions changed and a savannah\/grassland environment became more widespread, the tree cover would become less dense, scattered, and sparse such that bipedalism would become more important.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">There are several proposed selective pressures for bipedalism:<\/span><\/p>\n<ol>\n<li class=\"import-Normal\" style=\"background-color: transparent;text-align: left;text-indent: 0pt\"><span style=\"color: #000000\"><strong>E<\/strong><strong>nergy conservation:<\/strong> Modern bipedal humans conserve more energy than extant chimpanzees, which are predominantly knuckle-walking quadrupeds when walking over land. While chimpanzees, for instance, are faster than humans terrestrially, they expend large amounts of energy being so. Adaptations to bipedalism include \u201cstacking\u201d the majority of the weight of the body over a small area around the centre of gravity (i.e., the head is above the chest, which is above the pelvis, which is over the knees, which are above the feet). This reduces the amount of muscle needed to be engaged during locomotion to \u201cpull us up\u201d and allows us to travel longer distances expending far less energy.<\/span><\/li>\n<li class=\"import-Normal\" style=\"background-color: transparent;text-align: left;text-indent: 0pt\"><span style=\"color: #000000\"><strong>T<\/strong><strong>hermoregulation:<\/strong> Less surface area (i.e., only the head and shoulders) is exposed to direct sunlight during the hottest parts of the day (i.e., midday). This means that the body has less need to employ additional \u201ccooling\u201d mechanisms such as sweating, which additionally means less water loss.<\/span><\/li>\n<li class=\"import-Normal\" style=\"background-color: transparent;text-align: left;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Bipedalism <\/strong><span style=\"text-decoration: underline\">(Freeing of Hands)<\/span><strong>: <\/strong>This method of locomotion freed up our ancestors\u2019 hands such that they could more easily gather food and carry tools or infants. This further enabled the use of hands for more specialized adaptations associated with the manufacturing and use of tools.<\/span><\/li>\n<\/ol>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">These selective pressures are not mutually exclusive. Bipedality could have evolved from a combination of these selective pressures, in ways that increased the chances of early hominin survival.<\/span><\/p>\n<h3 class=\"import-Normal\"><span style=\"color: #000000\"><strong>Skeletal Adaptations for Bipedalism<\/strong><\/span><\/h3>\n<figure style=\"width: 405px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image10-1.png\" alt=\"A full human skeleton and gorilla skeleton standing in upright positions next to each other.\" width=\"405\" height=\"452\" \/><figcaption class=\"wp-caption-text\"><span style=\"color: #000000\">Figure 10.6: Compared to gorillas (right) and other apes, humans (left) have highly specialized adaptations to facilitate bipedal locomotion. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Primatenskelett-drawing.jpg\" target=\"_blank\">Skeleton of human (1) and gorilla (2), unnaturally sketched<\/a> by unknown from Brehms Tierleben, Small Edition 1927 is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\" target=\"_blank\">public domain<\/a>.<br \/><\/span><\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Humans have highly specialized adaptations to facilitate obligate bipedalism (Figure 10.6). Many of these adaptations occur within the soft tissue of the body (e.g., muscles and tendons). However, when analyzing the paleoanthropological record for evidence of the emergence of bipedalism, all that remains is the fossilized bone. Interpretations of locomotion are therefore often based on comparative analyses between fossil remains and the skeletons of extant primates with known locomotor behaviours. These adaptations occur throughout the skeleton and are summarized in Figure 10.7.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">The majority of these adaptations occur in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1336\"><strong>postcranium<\/strong><\/a> and are outlined in Figure 10.7. In general, these adaptations allow for greater stability and strength in the lower limb, by allowing for more shock absorption, for a larger surface area for muscle attachment, and for the \u201cstacking\u201d of the skeleton directly over the centre of gravity to reduce energy needed to be kept upright. These adaptations often mean less flexibility in areas such as the knee and foot.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">However, these adaptations come at a cost. Evolving from a nonobligate bipedal ancestor means that the adaptations we have are evolutionary compromises. For instance, the valgus knee (angle at the knee) is an essential adaptation to balance the body weight above the ankle during bipedal locomotion. However, the strain and shock absorption at an angled knee eventually takes its toll. For example, runners often experience joint pain. Similarly, the long neck of the femur absorbs stress and accommodates for a larger pelvis, but it is a weak point, resulting in hip replacements being commonplace among the elderly, especially in cases where the bone additionally weakens through osteoporosis. Finally, the S-shaped curve in our spine allows us to stand upright, relative to the more curved C-shaped spine of an LCA. Yet the weaknesses in the curves can lead to pinching of nerves and back pain. Since many of these problems primarily are only seen in old age, they can potentially be seen as an evolutionary compromise.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Despite relatively few postcranial fragments, the fossil record in early hominins indicates a complex pattern of emergence of bipedalism. Key features, such as a more anteriorly placed foramen magnum, are argued to be seen even in the earliest discovered hominins, indicating an upright posture (Dart 1925). Some early species appear to have a mix of ancestral (arboreal) and derived (bipedal) traits, which indicates a mixed locomotion and a more <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1392\">mosaic evolution<\/a><\/strong> of the trait. Some early hominins appear to, for instance, have bowl-shaped pelvises (hip bones) and angled femurs suitable for bipedalism but also have retained an opposable <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1360\">hallux<\/a><\/strong> (big toe) or curved fingers and longer arms (for arboreal locomotion). These mixed morphologies may indicate that earlier hominins were not fully obligate bipeds and thus thrived in mosaic environments. <\/span><span style=\"color: #000000\">Yet the associations between postcranial and the more diagnostic cranial fossils and bones are not always clear, muddying our understanding of the specific species to which fossils belong (Grine et al. 2022).<\/span><\/p>\n<p><span style=\"color: #000000\">It is also worth noting that, while not directly related to bipedalism per se, other postcranial adaptations are evident in the hominin fossil record from some of the earlier hominins. For instance, the hand and finger morphologies of many of the earliest hominins indicate adaptations consistent with arboreality. These include longer hands, more curved metacarpals and phalanges (long bones in the hand and fingers, respectively), and a shorter, relatively weaker thumb. This allows for gripping onto curved surfaces during locomotion. The earliest hominins appear to have mixed morphologies for both bipedalism and arborealism. However, among Australopiths (members of the genus, Australopithecus), there are indications for greater reliance on bipedalism as the primary form of locomotion. Similarly, adaptations consistent with tool manufacture (shorter fingers and a longer, more robust thumb, in contrast to the features associated with arborealism) have been argued to appear before the genus <em>Homo<\/em>.<\/span><\/p>\n<table class=\"no-lines landscape alignleft\" style=\"border-collapse: collapse;width: 98.92%;height: 54px\" border=\"0\">\n<tbody>\n<tr style=\"height: 67px\">\n<td style=\"width: 100%;height: 54px\">Figure 10.7: Skeletal comparisons between modern humans (obligate bipeds) and nonobligate bipeds (e.g., chimpanzees). Credit:<a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/chapter-9-early-hominins-2\/\" target=\"_blank\"> Skeletal comparisons between modern humans and nonobligate bipeds (Figure 9.6)<\/a> original to<a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\"> Explorations: An Open Invitation to Biological Anthropology<\/a> is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\"> CC BY-NC 4.0 License<\/a>.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<div align=\"left\">\n<table class=\"grid\">\n<thead>\n<tr>\n<td style=\"width: 97.998px\"><strong>Region<\/strong><\/td>\n<td style=\"width: 106.992px\"><strong>Feature<\/strong><\/td>\n<td style=\"width: 366.992px\"><strong>Obligate Biped (H. sapiens)<\/strong><\/td>\n<td style=\"width: 310px\"><strong>Nonobligate Biped<\/strong><\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td style=\"width: 97.998px\">Cranium<\/td>\n<td style=\"width: 106.992px\">Position of the foramen magnum<\/td>\n<td style=\"width: 366.992px\">Positioned inferiorly (immediately under the cranium) so that the head rests on top of the vertebral column for balance and support (head is perpendicular to the ground).<\/td>\n<td style=\"width: 310px\">Posteriorly positioned (to the back of the cranium). Head is positioned parallel to the ground.<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 97.998px\">Post<\/p>\n<p>cranium<\/td>\n<td style=\"width: 106.992px\">Body proportions<\/td>\n<td style=\"width: 366.992px\">Shorter upper limb (not used for locomotion).<\/td>\n<td style=\"width: 310px\">Longer upper limbs (used for locomotion).<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 97.998px\">Post<\/p>\n<p>cranium<\/td>\n<td style=\"width: 106.992px\">Spinal curvature<\/td>\n<td style=\"width: 366.992px\">S-curve due to pressure exerted on the spine from bipedalism (lumbar lordosis).<\/td>\n<td style=\"width: 310px\">C-curve.<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 97.998px\">Post<\/p>\n<p>cranium<\/td>\n<td style=\"width: 106.992px\">Vertebrae<\/td>\n<td style=\"width: 366.992px\">Robust lumbar (lower-back) vertebrae (for shock absorbance and weight bearing). Lower back is more flexible than that of apes as the hips and trunk swivel when walking (weight transmission).<\/td>\n<td style=\"width: 310px\">Gracile lumbar vertebrae compared to those of modern humans.<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 97.998px\">Post<\/p>\n<p>cranium<\/td>\n<td style=\"width: 106.992px\">Pelvis<\/td>\n<td style=\"width: 366.992px\">Shorter, broader, bowl-shaped pelvis (for support); very robust. Broad sacrum with large sacroiliac joint surfaces.<\/td>\n<td style=\"width: 310px\">Longer, flatter, elongated ilia; more narrow and gracile; narrower sacrum; relatively smaller sacroiliac joint surface.<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 97.998px\">Post<\/p>\n<p>cranium<\/td>\n<td style=\"width: 106.992px\">Lower limb<\/td>\n<td style=\"width: 366.992px\">In general, longer, more robust lower limbs and more stable, larger joints.<\/p>\n<ul>\n<li style=\"font-weight: 400\">Large femoral head and longer neck (absorbs more stress and increases the mechanical advantage).<\/li>\n<li style=\"font-weight: 400\">Valgus knee, in which the angle of the knee positions it over the ankle and keeps the centre of gravity balanced over the stance leg during stride cycle (shock absorbance).<\/li>\n<li style=\"font-weight: 400\">Distal tibia (lower leg) of humans has a large medial malleolus for stability.<\/li>\n<\/ul>\n<\/td>\n<td style=\"width: 310px\">In general, smaller, more gracile limbs with more flexible joints.<\/p>\n<ul>\n<li style=\"font-weight: 400\">Femoral neck is smaller in comparison to modern humans and shorter.<\/li>\n<li style=\"font-weight: 400\">The legs bow outward, and there is no valgus angle of the knee (no \u201cknock knees\u201d).<\/li>\n<li style=\"font-weight: 400\">The distal tibia in chimpanzees is trapezoid (wider anteriorly) for climbing and allows more flexibility.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 97.998px\">Post<\/p>\n<p>cranium<\/td>\n<td style=\"width: 106.992px\">Foot<\/td>\n<td style=\"width: 366.992px\">Rigid, robust foot, without a midtarsal break.<\/p>\n<p>Nonopposable and large, robust big toe (for push off while walking) and large heel for shock absorbance.<\/td>\n<td style=\"width: 310px\">Flexible foot, midtarsal break present (which allows primates to lift their heels independently from their feet), opposable big toe for grasping.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div class=\"textbox shaded\" style=\"background: var(--lightblue)\">\n<h2>Special Topic: Fear of Snakes \u2014 A Cultural or Biological Adaptation?<\/h2>\n<figure id=\"attachment_680\" aria-describedby=\"caption-attachment-680\" style=\"width: 393px\" class=\"wp-caption alignright\"><img class=\"wp-image-680\" src=\"http:\/\/opentextbooks.concordia.ca\/explorationsversiontwo\/wp-content\/uploads\/sites\/71\/2023\/06\/snake-2319873_1920.jpg\" alt=\"\" width=\"393\" height=\"262\" \/><figcaption id=\"caption-attachment-680\" class=\"wp-caption-text\">Figure 10.8: A constricting snake (adder) with patterned scales and opened mouth. Credit: <em data-start=\"542\" data-end=\"582\">Snake, Adder, Serpent, Reptile, Animal<\/em> is free to use under the Pixabay <a href=\"https:\/\/pixabay.com\/service\/license-summary\/\" target=\"_blank\">Content License.<\/a><\/figcaption><\/figure>\n<p>It is suggested that primates have three major predators: raptors, felines, and snakes; however, many studies show that of these carnivores, snakes were one of the first that mammals had to contend with alongside dinosaurs, as felines and raptors evolved at a much slower pace than their reptilian competition. Herpetologists trace the evolution of constricting snakes to about 100 million years ago, and by the time mammals arrived around 75 million years ago, constrictors were\u00a0 already well established as a formidable threat (Greene, 2017). \u00a0Both co-existed for millennia and each sustained selective pressures requiring them to evolve specific traits to survive. When venomous snakes eventually emerged 55 to 65 million years ago, they posed yet an additional threat to proto-primates as they required less distance for the predator to kill (2017). Alongside camouflage and silent movement techniques, it was the development of the snake\u2019s hollow fangs through which to deliver venom that was most transformative to primate evolution. As such, primates evolved their pre-conscious attention, and visual acuity to cope with this new threat; therefore, while snakes were adapting morphologically to feed themselves, they were unwittingly teaching proto-primates valuable lessons in predator detection and reacting appropriately in order to survive.<\/p>\n<p>In a 2009 Harvard University study, Lynne A. Isbell hypothesizes that envenoming snakes are linked to being directly responsible for the origins of the evolving complex brains and superior visual capacity in the lineage of anthropoids leading to humans (Isbell, 2009). Forward-facing eyes for binocular vision, depth perception, enhanced visual acuity, stereoscopic and trichromatic colour vision, all traits necessary for snake detection; and the quick motor responses from the primate\u2019s fight, flight, or freeze defence mechanism to circumvent a snake\u2019s squeeze or bite. Numerous laboratory studies show that humans and primates both sense and visually detect snakes more rapidly than other threatening stimuli (Van Le et al., 2013). These experiments show that snakes elicited the strongest, fastest responses (Van Le et al., 2013). This is known as \u2018Snake Detection Theory\u2019 and is the evolution of the primate\u2019s complex brain, visual acuity, and rapid motor responses towards snakes in its environment that are the adaptations needed to live successfully as arboreal beings. It is not fortuitous then, that primates that never coexisted with venomous snakes, such as lemurs in Madagascar, have less visual acuity, better olfaction and smaller brains. Within Isbell\u2019s work, a collaborative study by a group of neuroscientists tested this hypothesis and found that, indeed, there is higher neural firing and activity in multiple areas of the primate brain, notably in the pulvinar, a region responsible for visual attention and oculomotor behaviour (Isbell, L., 2009).<\/p>\n<figure style=\"width: 316px\" class=\"wp-caption alignleft\"><img src=\"https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/9\/96\/Ra_slays_Apep_%28tomb_scene_in_Deir_el-Medina%29%28improved_contrast%29.png\/250px-Ra_slays_Apep_%28tomb_scene_in_Deir_el-Medina%29%28improved_contrast%29.png\" alt=\"File:Ra slays Apep (tomb scene in Deir el-Medina)(improved contrast).png\" width=\"316\" height=\"236\" \/><figcaption class=\"wp-caption-text\">Figure 10.9: Tomb scene depicting the serpent god Apep (Apophis) wounded by the cat god Miuty, alternatively the sun god Ra in cat form, from a tomb in Deir el-Medina, Luxor, Egypt. Credit: <em data-start=\"265\" data-end=\"331\">Ra slays Apep (tomb scene in Deir el-Medina) (improved contrast)<\/em> by Hajor is under <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/deed.en\" target=\"_blank\">Creative Commons Attribution-Share Alike 3.0<\/a><\/figcaption><\/figure>\n<p>Today, the fear of snakes is widespread in humans, often shown through avoidance and disgust. A study in <em data-start=\"197\" data-end=\"244\">The Journal of Ethnobiology and Ethnomedicine<\/em> notes that snakes are over-hunted and excluded from conservation efforts worldwide (Cer\u00edaco, 2012). While cultural factors shape our sentiments, instinct also plays a role\u2014such as the developed avoidance behaviours toward threats like snakes. This blend of instinct and cultural influence is not only seen in behaviour but also deeply embedded in the stories we tell. Many cultures depict mythological snakes as harbingers of death or chaos. In the Bible, Satan becomes a snake to tempt Eve. Norse mythology features J\u00f6rmungandr, the world serpent who signals the apocalypse. Egyptian myth tells of Apophis, who battles the sun god Ra nightly. Though sources vary, these myths consistently portray snakes as threats. As such, the widespread fear of snakes may reflect both evolutionary and cultural influences. Understood as an adaptive response inherited from primate ancestors\u2014who developed avoidance behaviours toward potentially dangerous stimuli\u2014and reinforced through myths and religious narratives, the enduring presence of snakes as potent figures of fear across human societies and primate groups highlights the complex intertwining of instinct and cultural meaning in shaping human behaviour.<\/p>\n<\/div>\n<h2 class=\"import-Normal\"><span style=\"color: #000000\"><strong>Early Hominins: Sahelanthropus and Orrorin<\/strong><\/span><\/h2>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">We see evidence for bipedalism in some of the earliest fossil hominins, dated from within our estimates of our divergence from chimpanzees. These hominins, however, also indicate evidence for arboreal locomotion.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">The earliest dated hominin find (between 6 mya and 7 mya, based on radiometric dating of volcanic tufts) has been argued to come from Chad and is named <strong><em>Sahelanthropus tchadensis<\/em> <\/strong>(Figure 10.10; Brunet et al. 1995). The initial discovery was made in 2001 by Ahounta Djimdoumalbaye and announced in <em>Nature<\/em> in 2002 by a team led by French paleontologist Michel Brunet. The find has a small cranial capacity (360 cc) and smaller canines than those in extant great apes, though they are larger and pointier than those in humans. This might imply that, over evolutionary time, the need for display and dominance among males has reduced, as has our sexual dimorphism. A short cranial base and a foramen magnum that is more humanlike in positioning have been argued to indicate upright walking.<\/span><\/p>\n<figure id=\"attachment_304\" aria-describedby=\"caption-attachment-304\" style=\"width: 640px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-288\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/9.82.jpg\" alt=\"Four views of a beige-colored skull are seen against a black background.\" width=\"640\" height=\"640\" \/><figcaption id=\"caption-attachment-304\" class=\"wp-caption-text\">Figure 10.10: Sahelanthropus tchadensis exhibits a set of derived features, including a long, low cranium; a small, ape-sized braincase; and relatively reduced prognathism. Credit: aa <a href=\"https:\/\/efossils.org\/page\/boneviewer\/Sahelanthropus%20tchadensis\/TM%20266-01-060-1\" target=\"_blank\">Sahelanthropus tchadensis: TM 266-01-060-1 anterior view<\/a> by \u00a9<a href=\"https:\/\/www.efossils.org\/\" target=\"_blank\">eFossils<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\" target=\"_blank\">CC BY-NC-SA 2.0 License<\/a> and is <a href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\" target=\"_blank\">used as outlined by eFossils<\/a>; b <a href=\"https:\/\/efossils.org\/page\/boneviewer\/Sahelanthropus%20tchadensis\/TM%20266-01-060-1\" target=\"_blank\">Sahelanthropus tchadensis: TM 266-01-060-1 posterior view<\/a> by \u00a9<a href=\"https:\/\/www.efossils.org\/\" target=\"_blank\">eFossils<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\" target=\"_blank\">CC BY-NC-SA 2.0 License<\/a> and is <a href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\" target=\"_blank\">used as outlined by eFossils<\/a>; c <a href=\"https:\/\/efossils.org\/page\/boneviewer\/Sahelanthropus%20tchadensis\/TM%20266-01-060-1\" target=\"_blank\">Sahelanthropus tchadensis: TM 266-01-060-1 inferior view<\/a> by \u00a9<a href=\"https:\/\/www.efossils.org\/\" target=\"_blank\">eFossils<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\" target=\"_blank\">CC BY-NC-SA 2.0 License<\/a> and is <a href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\" target=\"_blank\">used as outlined by eFossils<\/a>; and d <a href=\"https:\/\/efossils.org\/page\/boneviewer\/Sahelanthropus%20tchadensis\/TM%20266-01-060-1\" target=\"_blank\">Sahelanthropus tchadensis: TM 266-01-060-1 lateral left view<\/a> by \u00a9<a href=\"https:\/\/www.efossils.org\/\" target=\"_blank\">eFossils<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\" target=\"_blank\">CC BY-NC-SA 2.0 License<\/a> and is <a href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\" target=\"_blank\">used as outlined by eFossils<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">Initially, the inclusion of <em>Sahelanthropus<\/em> in the hominin family was debated by researchers, since the evidence for bipedalism is based on cranial evidence alone, which is not as convincing as postcranial evidence. Yet, a femur (thigh bone) and ulnae (upper arm bones) thought to belong to <em>Sahelanthropus<\/em> was discovered in 2001 (although not published until 2022). These bones may support the idea that the hominin was in fact a terrestrial biped with arboreal capabilities and behaviours (Daver et al. 2022).<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong><em>Orrorin tugenensis<\/em><\/strong> (Orrorin meaning \u201coriginal man\u201d), dated to between 6 mya and 5.7 mya, was discovered near Tugen Hills in Kenya in 2000. Smaller <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1361\">cheek teeth<\/a><\/strong> (molars and premolars) than those in even more recent hominins, thick enamel, and reduced, but apelike, canines characterize this species. This is the first species that clearly indicates adaptations for bipedal locomotion, with fragmentary leg, arm, and finger bones having been found but few cranial remains. One of the most important elements discovered was a proximal femur, BAR 1002'00. The femur is the thigh bone, and the proximal part is that which articulates with the pelvis; this is very important for studying posture and locomotion. This femur indicates that <em>Ororrin<\/em> was bipedal, and recent studies suggest that it walked in a similar way to later <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1393\">Pliocene<\/a><\/strong> hominins. Some have argued that features of the finger bones suggest potential tool-making capabilities, although many researchers argue that these features are also consistent with climbing.<\/span><\/p>\n<h3 class=\"import-Normal\"><strong><span style=\"color: #000000\">Early Hominins: The Genus <em>Ardipithecus<\/em><\/span><\/strong><\/h3>\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Another genus, <em>Ardipithecus<\/em>, is argued to be represented by at least two species: <em>Ardipithecus (Ar.) ramidus <\/em>and <em>Ar. kadabba<\/em>.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong><em>Ardipithecus ramidus<\/em><\/strong> (\u201cramid\u201d means root in the Afar language) is currently the best-known of the earliest hominins (Figure 10.11). Unlike <em>Sahelanthropus<\/em> and<em> Orrorin<\/em>, this species has a large sample size of over 110 specimens from Aramis alone. Dated to 4.4 mya, <em>Ar. ramidus<\/em> was found in Ethiopia (in the Middle Awash region and in Gona). This species was announced in 1994 by American palaeoanthropologist Tim White, based on a partial female skeleton nicknamed \u201cArdi\u201d (ARA-VP-6\/500; White et al. 1994). Ardi demonstrates a mosaic of ancestral and derived characteristics in the postcrania. For instance, she had an opposable big toe (hallux), similar to chimpanzees (i.e., more ancestral), which could have aided in climbing trees effectively. However, the pelvis and hip show that she could walk upright (i.e., it is derived), supporting her hominin status. A small brain (300 cc to 350 cc), midfacial projection, and slight prognathism show retained ancestral cranial features, but the cheek bones are less flared and robust than in later hominins.<\/span><\/p>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_304-2\" aria-describedby=\"caption-attachment-304-2\" style=\"width: 706px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-289\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/9.9-scaled-1.jpg\" alt=\"Skull cast and partial skeleton with photographs of some bones and line drawings of others.\" width=\"706\" height=\"453\" \/><figcaption id=\"caption-attachment-304-2\" class=\"wp-caption-text\">Figure 10.11a and b: Researchers believe that Ardipithecus ramidus was able to walk upright, although not as efficiently as later humans. It possessed the musculature required for tree climbing, and while moving quadrupedally, it likely placed weight on the palms of the hands rather than on the knuckles. Credit: a. <a class=\"rId61\" href=\"https:\/\/boneclones.com\/product\/ardipithecus-ramidus-skull-BH-039\" target=\"_blank\">Ardipithecus ramidus Skull<\/a> by <a class=\"rId62\" href=\"https:\/\/boneclones.com\/\" target=\"_blank\">\u00a9BoneClones<\/a> is used by permission and available here under a <a class=\"rId63\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>; b. <a class=\"rId64\" href=\"https:\/\/boneclones.com\/product\/ardipithecus-ramidus-skull-BH-039\" target=\"_blank\">Artist\u2019s rendition of \u201cArdi\u201d skeleton<\/a> by <a class=\"rId65\" href=\"https:\/\/boneclones.com\/\" target=\"_blank\">\u00a9BoneClones<\/a> is used by permission and available here under a <a class=\"rId66\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong><em>Ardipithecus kadabba<\/em><\/strong> (the species name means \u201coldest ancestor\u201d in the Afar language) is known from localities on the western margin of the Middle Awash region, the same locality where <em>Ar. ramidus<\/em> has been found. Specimens include mandibular fragments and isolated teeth as well as a few postcranial elements from the Asa Koma (5.5 mya to 5.77 mya) and Kuseralee Members (5.2 mya), well-dated and understood (but temporally separate) volcanic layers in East Africa. This species was discovered in 1997 by paleoanthropologist Dr. Yohannes Haile-Selassie. Originally these specimens were referred to as a subspecies of <em>Ar. ramidus<\/em>. In 2002, six teeth were discovered at Asa Koma and the dental-wear patterns confirmed that this was a distinct species, named <em>Ar. kadabba,<\/em> in 2004. One of the postcranial remains recovered included a 5.2 million-year-old toe bone that demonstrated features that are associated with toeing off (pushing off the ground with the big toe leaving last) during walking, a characteristic unique to bipedal walkers. However, the toe bone was found in the Kuseralee Member, and therefore some doubt has been cast by researchers about its association with the teeth from the Asa Koma Member.<\/span><\/p>\n<h2 class=\"import-Normal\"><span style=\"color: #000000\">Derived Adaptations: Early Hominin Dention<\/span><\/h2>\n<h3 class=\"import-Normal\"><strong><span style=\"color: #000000\">The Importance of Teeth<\/span><\/strong><\/h3>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Teeth are abundant in the fossil record, primarily because they are already highly mineralized as they are forming, far more so than even bone. Because of this, teeth preserve readily. And, because they preserve readily, they are well-studied and better understood than many skeletal elements. In the sparse hominin (and primate) fossil record, teeth are, in some cases, all we have.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Teeth also reveal a lot about the individual from whom they came. We can tell what they evolved to eat, to which other species they may be closely related, and even, to some extent, the level of sexual dimorphism, or general variability, within a given species. This is powerful information that can be contained in a single tooth. With a little more observation, the wearing patterns on a tooth can tell us about the diet of the individual in the weeks leading up to its death. Furthermore, the way in which a tooth is formed, and the timing of formation, can reveal information about changes in diet (or even mobility) over infancy and childhood, using isotopic analyses. When it comes to our earliest hominin relatives, this information is vital for understanding how they lived.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">The purpose of comparing different hominin species is to better understand the functional morphology as it applies to dentition. In this, we mean that the morphology of the teeth or masticatory system (which includes jaws) can reveal something about the way in which they were used and, therefore, the kinds of foods these hominins ate. When comparing the features of hominin groups, it is worth considering modern analogues (i.e., animals with which to compare) to make more appropriate assumptions about diet. In this way, hominin dentition is often compared with that of chimpanzees and gorillas (our close ape relatives), as well as with that of modern humans.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">The most divergent group, however, is humans. Humans around the world have incredibly varied diets. Among hunter-gatherers, it can vary from a honey- and plant-rich diet, as seen in the Hadza in Tanzania, to a diet almost entirely reliant on animal fat and protein, as seen in Inuits in polar regions of the world. We are therefore considered generalists, more general than the largely <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1362\">frugivorous<\/a><\/strong> (fruit-eating) chimpanzee or the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1363\">folivorous<\/a><\/strong> (foliage-eating) gorilla, as discussed in Chapter 6.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">One way in which all humans are similar is our reliance on the processing of our food. We cut up and tear meat with tools using our hands, instead of using our front teeth (incisors and canines). We smash and grind up hard seeds, instead of crushing them with our hind teeth (molars). This means that, unlike our ape relatives, we can rely more on developing tools to navigate our complex and varied diets. <span style=\"text-decoration: underline\">(We could say)<\/span> Our brain, therefore, is our primary masticatory organ. Evolutionarily, our teeth have reduced in size and our faces are flatter, or more <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1364\">orthognathic<\/a>, <\/strong>partially in response to our increased reliance on our hands and brain to process food. Similarly, a reduction in teeth and a more generalist dental morphology could also indicate an increase in softer and more variable foods, such as the inclusion of more meat. The link has been made between some of the earliest evidence for stone tool manufacture, the earliest members of our genus, and the features that we associate with these specimens.<\/span><\/p>\n<h3 class=\"import-Normal\"><strong><span style=\"color: #000000\">General Dental Trends in Early Hominins<\/span><\/strong><\/h3>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Several trends are visible in the dentition of early hominins. However, all tend to have the same <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1365\">dental formula<\/a><\/strong>. The dental formula tells us how many of each tooth type are present in each quadrant of the mouth. Going from the front of the mouth, this includes the square, flat <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1271\">incisors<\/a><\/strong>; the pointy <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1274\">canines<\/a><\/strong>; the small, flatter <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1366\">premolars<\/a><\/strong>; and the larger hind <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1273\">molars<\/a><\/strong>. In many primates, from Old World monkeys to great apes, the typical dental formula is 2:1:2:3. This means that if we divide the mouth into quadrants, each has two incisors, one canine, two premolars, and three molars. The eight teeth per quadrant total 32 teeth in all (although some humans have fewer teeth due to the absence of their wisdom teeth, or third molars).<\/span><\/p>\n<figure style=\"width: 380px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image24.png\" alt=\"Anterior view of the lower face of a person showing their teeth.\" width=\"380\" height=\"253\" \/><figcaption class=\"wp-caption-text\">Figure 10.12: In humans, our canines are often a similar size to our incisors. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Adult_human_teeth.jpg\" target=\"_blank\">Adult human teeth<\/a> by <a href=\"https:\/\/www.genusfotografen.se\/\" target=\"_blank\">Genusfotografen<\/a> (Tomas Gunnarsson) through <a href=\"https:\/\/wikimedia.se\/\" target=\"_blank\">Wikimedia Sverige<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\" target=\"_blank\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<p><span style=\"color: #000000\">The morphology of the individual teeth is where we see the most change. Among primates, large incisors are associated with food procurement or preparation (such as biting small fruits), while small incisors indicate a diet that may contain small seeds or leaves (where the preparation is primarily in the back of the mouth). Most hominins have relatively large, flat, vertically aligned incisors that <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1389\">occlude<\/a> <\/strong>(touch) relatively well, forming a \u201cbite.\u201d This differs from, for instance, the orangutan, whose teeth stick out (i.e.<em>,<\/em> are <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1367\">procumbent<\/a><\/strong>).<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">While the teeth are often aligned with diet, the canines may be misleading in that regard. We tend to associate pointy, large canines with the ripping required for meat, and the reduction (or, in some animals, the absence) of canines as indicative of herbivorous diets. In humans, our canines are often a similar size to our incisors and therefore considered <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1390\">incisiform<\/a> <\/strong>(Figure 10.12). However, our closest relatives all have very long, pointy canines, particularly on their upper dentition. This is true even for the gorilla, which lives almost exclusively on plants. The canines in these instances reveal more about social structure and sexual dimorphism than diet, as large canines often signal dominance.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Early on in human evolution, we see a reduction in canine size. <em>Sahelanthropus tchadensis<\/em> and <em>Orrorin tugenensis<\/em> both have smaller canines than those in extant great apes, yet the canines are still larger and pointier than those in humans or more recent hominins. This might suggest that, over evolutionary time, the need for display and dominance among males has reduced, as has our sexual dimorphism. In <em>Ardipithecus ramidus<\/em>, there is no obvious difference between male and female canine size, yet they are still slightly larger and pointier than in modern humans. This implies a less sexually dimorphic social structure in the earlier hominins relative to modern-day chimpanzees and gorillas.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Along with a reduction in canine size is the reduction or elimination of a canine <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1277\">diastema<\/a>:<\/strong> a gap between the teeth on the mandible that allows room for elongated teeth on the maxilla to \u201cfit\u201d in the mouth. Absence of a diastema is an excellent indication of a reduction in canine size. In animals with large canines (such as baboons), there is also often a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1368\">honing P3<\/a><\/strong>, where the first premolar (also known as P3 for evolutionary reasons) is triangular in shape, \u201csharpened\u201d by the extended canine from the upper dentition. This is also seen in some early hominins: <em>Ardipithecus<\/em>, for example, has small canines that are almost the same height as its incisors, although still larger than those in recent hominins.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">The hind dentition, such as the bicuspid (two cusped) premolars or the much larger molars, are also highly indicative of a generalist diet in hominins. Among the earliest hominins, the molars are larger than we see in our genus, increasing in size to the back of the mouth and angled in such a way from the much smaller anterior dentition as to give these hominins a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1369\">parabolic<\/a><\/strong> (V-shaped) dental arch. This differs from our living relatives and some early hominins, such as <em>Sahelanthropus<\/em>, whose molars and premolars are relatively parallel between the left and right sides of the mouth, creating a U-shape.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Among more recent early hominins, the molars are larger than those in the earliest hominins and far larger than those in our own genus, <em>Homo.<\/em> Large, short molars with thick <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1370\">enamel<\/a><\/strong> allowed our early cousins to grind fibrous, coarse foods, such as sedges, which require plenty of chewing. This is further evidenced in the low <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1279\">cusps<\/a>,<\/strong> or ridges, on the teeth, which are ideal for chewing. In our genus, the hind dentition is far smaller than in these early hominins. Our teeth also have medium-size cusps, which allow for both efficient grinding and tearing\/shearing meats.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Understanding the dental morphology has allowed researchers to extrapolate very specific behaviours of early hominins. It is worth noting that while teeth preserve well and are abundant, a slew of other morphological traits additionally provide evidence for many of these hypotheses. Yet there are some traits that are ambiguous. For instance, while there are definitely high levels of sexual dimorphism in <em>Au. afarensis<\/em>, discussed in the next section, the canine teeth are reduced in size, implying that while canines may be useful indicators for sexual dimorphism, it is also worth considering other evidence.<\/span><\/p>\n<div class=\"textbox\">\n<h2 class=\"import-Normal\"><span style=\"color: #000000\">Special Topic: Contested Species<\/span><\/h2>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Many named species are highly debated and argued to have specimens associated with a more variable <em>Au. afarensis <\/em>or <em>Au. anamensis<\/em> species. Sometimes these specimens are dated to times when, or found in places in which, there are \u201cgaps\u201d in the palaeoanthropological record. These are argued to represent chronospecies or variants of <em>Au. afarensis<\/em>. However, it is possible that, with more discoveries, the distinct species types will hold.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\"><strong><em>Australopithecus bahrelghazali<\/em><\/strong> is dated to within the time period of <em>Au. afarensi<\/em>s (3.6 mya; Brunet et al. 1995) and was the first Australopithecine to be discovered in Chad in central Africa. Researchers argue that the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1371\">holotype<\/a><\/strong>, whom discoverers have named \u201cAbel,\u201d falls under the range of variation of <em>Au. afarensis<\/em> and therefore that <em>A. bahrelghazali<\/em> does not fall into a new species (Lebatard et al. 2008). If \u201cAbel\u201d is a member of <em>Au. afarensis<\/em>, the geographic range of the species would be greatly extended.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">On a different note, <strong><em>Australopithecus <\/em><\/strong><strong><em>deyiremada<\/em><\/strong> (meaning \u201cclose relative\u201d in the Ethiopian language of Afar) is dated to 3.5 mya to 3.3 mya and is based on fossil mandible bones discovered in 2011 in Woranso-Mille (in the Afar region of Ethiopia) by Yohannes Haile-Selassie, an Ethiopian paleoanthropologist (Haile-Selassie et al. 2019). The discovery indicated, in contrast to <em>Au. afarensis<\/em>, smaller teeth with thicker enamel (potentially suggesting a harder diet) as well as a larger mandible and more projecting cheekbones. This find may be evidence that more than one closely related hominin species occupied the same region at the same temporal period (Haile-Selassie et al. 2015; Spoor 2015) or that other <em>Au. afarensis<\/em> specimens have been incorrectly designated. However, others have argued that this species has been prematurely identified and that more evidence is needed before splitting the taxa, since the variation appears subtle and may be due to slightly different niche occupations between populations over time.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\"><strong><em>Australopithecus garhi<\/em><\/strong> is another species found in the Middle Awash region of Ethiopia. It is currently dated to 2.5 mya (younger than <em>Au. afarensis<\/em>). Researchers have suggested it fills in a much-needed temporal \u201cgap\u201d between hominin finds in the region, with some anatomical differences, such as a relatively large cranial capacity (450 cc) and larger hind dentition than seen in other gracile Australopithecines. Similarly, the species has been argued to have longer hind limbs than <em>Au. afarensis<\/em>, although it was still able to move arboreally (Asfaw et al. 1999). However, this species is not well documented or understood and is based on only several fossil specimens. More astonishingly, crude stone tools resembling Oldowan (which will be described later) have been found in association with <em>Au. garhi<\/em>. While lacking some of the features of the Oldowan, this is one of the earliest technologies found in direct association with a hominin.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\"><strong><em>Kenyanthopus<\/em><\/strong><strong><em> platyops<\/em><\/strong> (the name \u201cplatyops\u201d refers to its flatter-faced appearance) is a highly contested genus\/species designation of a specimen (KNM-WT 40000) from Lake Turkana in Kenya, discovered by Maeve Leakey in 1999 (Figure 10.13). Dated to between 3.5 mya and 3.2 mya, some have suggested this specimen is an <em>Australopithecus<\/em>, perhaps even <em>Au.<\/em> <em>afarensis<\/em> (with a brain size which is difficult to determine, yet appears small), while still others have placed this specimen in <em>Homo <\/em>(small dentition and flat-orthognathic face). While taxonomic placing of this species is quite divided, the discoverers have argued that this species is ancestral to <em>Homo<\/em>, in particular to <em>Homo <\/em><em>ruldolfensis<\/em> (Leakey et al. 2001). Some researchers have additionally associated the earliest tool finds from Lomekwi, Kenya, temporally (3.3 mya) and in close geographic proximity to this specimen.<\/span><\/p>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_304-3\" aria-describedby=\"caption-attachment-304-3\" style=\"width: 579px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-291 \" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/9.11.jpg\" alt=\"Four views of an ancient skull are shown on a black background.\" width=\"579\" height=\"579\" \/><figcaption id=\"caption-attachment-304-3\" class=\"wp-caption-text\">Figure 10.13: This specimen, KNM WT 40000 (Kenyanthopus platyops), has small detention, a small brain case, and a relatively flat face. Its genus\/species designation remains contested. Credit: a. <a class=\"rId76\" href=\"https:\/\/efossils.org\/page\/boneviewer\/Kenyanthropus%20platyops\/KNM%20WT%2040000\" target=\"_blank\"><em>Kenyanthropus platyops<\/em><\/a><a class=\"rId77\" href=\"https:\/\/efossils.org\/page\/boneviewer\/Kenyanthropus%20platyops\/KNM%20WT%2040000\" target=\"_blank\"> KNM WT 40000 anterior view<\/a> by \u00a9<a class=\"rId78\" href=\"https:\/\/www.efossils.org\/\">eFossils<\/a> is under a <a class=\"rId79\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\" target=\"_blank\">CC BY-NC-SA 2.0 License<\/a> and is <a class=\"rId80\" href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\" target=\"_blank\">used as outlined by eFossils<\/a>; b. <a class=\"rId81\" href=\"https:\/\/efossils.org\/page\/boneviewer\/Kenyanthropus%20platyops\/KNM%20WT%2040000\" target=\"_blank\"><em>Kenyanthropus platyops<\/em><\/a><a class=\"rId82\" href=\"https:\/\/efossils.org\/page\/boneviewer\/Kenyanthropus%20platyops\/KNM%20WT%2040000\" target=\"_blank\"> KNM WT 40000 superior view<\/a> by \u00a9<a class=\"rId83\" href=\"https:\/\/www.efossils.org\/\" target=\"_blank\">eFossils<\/a> is under a <a class=\"rId84\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\" target=\"_blank\">CC BY-NC-SA 2.0 License<\/a> and is <a class=\"rId85\" href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\" target=\"_blank\">used as outlined by eFossils<\/a>; c. <a class=\"rId86\" href=\"https:\/\/efossils.org\/page\/boneviewer\/Kenyanthropus%20platyops\/KNM%20WT%2040000\" target=\"_blank\"><em>Kenyanthropus platyops<\/em><\/a><a class=\"rId87\" href=\"https:\/\/efossils.org\/page\/boneviewer\/Kenyanthropus%20platyops\/KNM%20WT%2040000\" target=\"_blank\"> KNM WT 40000 lateral left view<\/a> by \u00a9<a class=\"rId88\" href=\"https:\/\/www.efossils.org\/\" target=\"_blank\">eFossils<\/a> is under a <a class=\"rId89\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\" target=\"_blank\">CC BY-NC-SA 2.0 License<\/a> and is <a class=\"rId90\" href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\" target=\"_blank\">used as outlined by eFossils<\/a>; d. <a class=\"rId91\" href=\"https:\/\/efossils.org\/page\/boneviewer\/Kenyanthropus%20platyops\/KNM%20WT%2040000\" target=\"_blank\"><em>Kenyanthropus platyops<\/em><\/a><a class=\"rId92\" href=\"https:\/\/efossils.org\/page\/boneviewer\/Kenyanthropus%20platyops\/KNM%20WT%2040000\" target=\"_blank\"> KNM WT 40000 inferior view<\/a> by \u00a9<a class=\"rId93\" href=\"https:\/\/www.efossils.org\/\" target=\"_blank\">eFossils<\/a> is under a <a class=\"rId94\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\" target=\"_blank\">CC BY-NC-SA 2.0 License<\/a> and is <a class=\"rId95\" href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\" target=\"_blank\">used as outlined by eFossils<\/a>.<\/figcaption><\/figure>\n<\/div>\n<h2 class=\"import-Normal\"><span style=\"color: #000000\">The Genus <em>Australopithecus<\/em><br \/>\n<\/span><\/h2>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">The Australopithecines are a diverse group of hominins, comprising various species. <em>Australopithecus<\/em> is the given group or genus name. It stems from the Latin word <em>Australo<\/em>, meaning \u201csouthern,\u201d and the Greek word <em>pithecus,<\/em> meaning \u201cape.\u201d Within this section, we will outline these differing species\u2019 geological and temporal distributions across Africa, unique derived and\/or shared traits, and importance in the fossil record.<\/span><\/p>\n<figure style=\"width: 381px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image37-2.png\" alt=\"A skull has a pronounced sagittal crest, flaring cheekbones, and large hind teeth.\" width=\"381\" height=\"585\" \/><figcaption class=\"wp-caption-text\">Figure 10.14: Robust Australopithecines such as Paranthropus boisei had large molars and chewing muscles. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Paranthropus_boisei_skull.jpg\" target=\"_blank\">Paranthropus boisei skull<\/a> by Durova is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/deed.en\" target=\"_blank\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Between 3 mya and 1 mya, there seems to be differences in dietary strategy between different species of hominins designated as Australopithecines. A pattern of larger posterior dentition (even relative to the incisors and canines in the front of the mouth), thick enamel, and cranial evidence for extremely large chewing muscles is far more pronounced in a group known as the robust australopithecines. This pattern is extreme<span style=\"text-decoration: underline\">ly<\/span> relative to their earlier contemporaries or predecessors, the gracile australopithecines<strong>,<\/strong> and is certainly larger than those seen in early <em>Homo<\/em>, which emerged during this time. This pattern of incredibly large hind dentition (and very small anterior dentition) has led people to refer to robust australopithecines as <strong>megadont<\/strong> hominins (Figure 10.14).<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Because of these differences, this section has been divided into \u201cgracile\u201d and \u201crobust\u201d Australopithecines, highlighting the morphological differences between the two groups (which many researchers have designated as separate genera: <em>Australopithecus<\/em> and <em>Paranthropus<\/em>, respectively) and then focusing on the individual species. It is worth noting, however, that not all researchers accept these clades as biologically or genetically distinct, with some researchers insisting that the relative gracile and robust features found in these species are due to parallel evolutionary events toward similar dietary niches.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Despite this genus\u2019 ancestral traits and small cranial capacity, all members show evidence of bipedal locomotion. It is generally accepted that <em>Australopithecus <\/em>species display varying degrees of arborealism along with bipedality.<\/span><\/p>\n<h3 class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Gracile Australopithecines<\/strong><\/span><\/h3>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">This section describes individual species from across Africa. These species are called \u201c<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1394\">gracile<\/a> <\/strong>australopithecines\u201d because of their smaller and less robust features compared to the divergent \u201c<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1395\">robust<\/a><\/strong>\u201d group. Numerous Australopithecine species have been named, but some are only based on a handful of fossil finds, whose designations are controversial.<\/span><\/p>\n<h4 class=\"import-Normal\"><em><span style=\"color: #000000\">East African Australopithecines<\/span><\/em><\/h4>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">East African Australopithecines are found throughout the EARS, and they include the earliest species associated with this genus. Numerous fossil-yielding sites, such as Olduvai, Turkana, and Laetoli, have excellent, datable stratigraphy, owing to the layers of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1372\">volcanic tufts<\/a><\/strong> that have accumulated over millions of years. These tufts may be dated using absolute dating techniques, such as Potassium-Argon dating (described in Chapter 8). This means that it is possible to know a relatively refined date for any fossil if the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1373\">context<\/a> <\/strong>of that find is known. Similarly, comparisons between the faunal assemblages of these stratigraphic layers have allowed researchers to chronologically identify environmental changes.<\/span><\/p>\n<figure style=\"width: 313px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image20-1-1.png\" alt=\"Occlusal view of an Au. anamensis mandible, with relatively large teeth, including canines.\" width=\"313\" height=\"313\" \/><figcaption class=\"wp-caption-text\">Figure 10.15: As seen in this mandible of KNM-KP 29281, Australopithecus anamensis had relatively large canine teeth. Credit: <a href=\"https:\/\/efossils.org\/page\/boneviewer\/Australopithecus%20anamensis\/KNM-KP%2029281\" target=\"_blank\">Australopithecus anamensis: KNM-KP 29281 occlusal view<\/a> by \u00a9<a href=\"https:\/\/www.efossils.org\/\" target=\"_blank\">eFossils<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\" target=\"_blank\">CC BY-NC-SA 2.0 License<\/a> and is <a href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\" target=\"_blank\">used as outlined by eFossils<\/a>.<\/figcaption><\/figure>\n<p><span style=\"color: #000000\">The earliest known Australopithecine is dated to 4.2 mya to 3.8 mya. <strong><em>Australopithecus anamensis<\/em><\/strong> (after \u201cAnam,\u201d meaning \u201clake\u201d from the Turkana region in Kenya; Leakey et al. 1995; Patterson and Howells 1967) is currently found from sites in the Turkana region (Kenya) and Middle Awash (Ethiopia; Figure 10.15). Recently, a 2019 find from Ethiopia, named MRD, after Miro Dora where it was found, was discovered by an Ethiopian herder named Ali Bereino. It is one of the most complete cranial finds of this species (Ward et al. 1999). A small brain size (370 cc), relatively large canines, projecting cheekbones, and earholes show more ancestral features as compared to those of more recent Australopithecines. The most important element discovered with this species is a fragment of a tibia (shinbone), which demonstrates features associated with weight transfer during bipedal walking. Similarly, the earliest found hominin femur belongs to this species. Ancestral traits in the upper limb (such as the humerus) indicate some retained arboreal locomotion.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">Some researchers suggest that <em>Au. anamensis<\/em> is an intermediate form of the chronospecies that becomes <em>Au. afarensis<\/em>, evolving from <em>Ar. ramidus<\/em>. However, this is debated, with other researchers suggesting morphological similarities and affinities with more recent species instead. Almost 100 specimens, representing over 20 individuals, have been found to date (Leakey et al. 1995; McHenry 2009; Ward et al. 1999).<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong><em>Au. afarensis<\/em><\/strong> is one of the oldest and most well-known australopithecine species and consists of a large number of fossil remains. <em>Au. afarensis<\/em> (which means \u201cfrom the Afar region\u201d) is dated to between 2.9 mya and 3.9 mya and is found in sites all along the EARS system, in Tanzania, Kenya, and Ethiopia (Figure 10.16). The most famous individual from this species is a partial female skeleton discovered in Hadar (Ethiopia), later nicknamed \u201cLucy,\u201d after the Beatles\u2019 song \u201cLucy in the Sky with Diamonds,\u201d which was played in celebration of the find (Johanson et al. 1978; Kimbel and Delezene 2009). This skeleton was found in 1974 by Donald Johanson and dates to approximately 3.2 mya. In addition, in 2002 a juvenile of the species was found by Zeresenay Alemseged and given the name \u201cSelam\u201d (meaning \u201cpeace,\u201d DIK 1-1), though it is popularly known as \u201cLucy\u2019s Child\u201d or as the \u201cDikika Child\u201d (Alemseged et al. 2006). Similarly, the \u201cLaetoli Footprints\u201d (discussed in Chapter 8; Hay and Leakey 1982; Leakey and Hay 1979) have drawn much attention.<\/span><\/p>\n<figure id=\"attachment_304-4\" aria-describedby=\"caption-attachment-304-4\" style=\"width: 643px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-294 \" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/9.14.jpg\" alt=\"Two images of life-like reconstructions of female and male Au. afarensis.\" width=\"643\" height=\"322\" \/><figcaption id=\"caption-attachment-304-4\" class=\"wp-caption-text\">Figure 10.16 a-b: Artistic reconstructions of Australopithecus afarensis by artist John Gurche. Female \u201cLucy\u201d is left and a male is on the right. Credit: a. <a class=\"rId106\" href=\"https:\/\/humanorigins.si.edu\/multimedia\/slideshows\/reconstructed-faces\" target=\"_blank\">Australopithecus afarensis, \u201cLucy,\u201d adult female. Reconstruction based on AL-288-1 by artist John Gurche, front view close-up<\/a> by <a class=\"rId107\" href=\"https:\/\/www.si.edu\/\" target=\"_blank\">the Smithsonian<\/a> [exhibit: \u201cReconstructed Faces: What Does It Mean to Be Human?\u201d] is <a class=\"rId108\" href=\"https:\/\/www.si.edu\/termsofuse\/\" target=\"_blank\">copyrighted and used for educational and noncommercial purposes as outlined by the Smithsonian<\/a>; b. <a class=\"rId109\" href=\"https:\/\/humanorigins.si.edu\/multimedia\/slideshows\/reconstructed-faces\" target=\"_blank\">Australopithecus afarensis, adult male. Reconstruction based on <\/a><a class=\"rId110\" href=\"https:\/\/humanorigins.si.edu\/multimedia\/slideshows\/reconstructed-faces\" target=\"_blank\">AL444-2<\/a><a class=\"rId111\" href=\"https:\/\/humanorigins.si.edu\/multimedia\/slideshows\/reconstructed-faces\" target=\"_blank\"> by John Gurche<\/a> by <a class=\"rId112\" href=\"https:\/\/www.si.edu\/\" target=\"_blank\">the Smithsonian<\/a> [exhibit: \u201cReconstructed Faces: What Does It Mean to Be Human?\u201d] is <a class=\"rId113\" href=\"https:\/\/www.si.edu\/termsofuse\/\" target=\"_blank\">copyrighted and used for educational and noncommercial purposes as outlined by the Smithsonian<\/a>.<\/figcaption><\/figure>\n<figure style=\"width: 320px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image40.png\" alt=\"A partial skeleton includes bones of the cranium, mandible, and postcranium.\" width=\"320\" height=\"772\" \/><figcaption class=\"wp-caption-text\">Figure 10.17: The humanlike femoral neck, valgus knee, and bowl-shaped hip seen in the \u201cLucy\u201d skeleton indicates that Australopithecus afarensis was bipedal. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Lucy_blackbg.jpg\" target=\"_blank\">Lucy blackbg<\/a> [AL 288-1, Australopithecus afarensis, cast from Museum national d'histoire naturelle, Paris] by 120 is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">The canines and molars of <em>Au. afarensis<\/em> are reduced relative to great apes but are larger than those found in modern humans (indicative of a generalist diet); in addition, <em>Au. afarensis <\/em>has a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1374\">prognathic<\/a><\/strong> face (the face below the eyes juts anteriorly) and robust facial features that indicate relatively strong chewing musculature (compared with <em>Homo<\/em>) but which are less extreme than in <em>Paranthropus<\/em>. Despite a reduction in canine size in this species, large overall size variation indicates high levels of sexual dimorphism.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">Skeletal evidence indicates that this species was bipedal, as its pelvis and lower limb demonstrate a humanlike femoral neck, valgus knee, and bowl-shaped hip (Figure 10.17). Further evidence of bipedalism is seen in the Laetoli Footprints, which are associated with <em data-start=\"92\" data-end=\"107\">Au. afarensis<\/em> (see Chapter 8). <\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Although not found in direct association with stone tools, potential evidence for cut marks on bones, found at Dikika, and dated to 3.39 mya indicates a possible temporal\/ geographic overlap between meat eating, tool use, and this species. However, this evidence is fiercely debated. Others have associated the cut marks with the earliest tool finds from Lomekwi, Kenya, temporally (3.3 mya) and in close geographic proximity to this species.<\/span><\/p>\n<h4 class=\"import-Normal\"><em><span style=\"color: #000000\">South African Australopithecines<\/span><\/em><\/h4>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Since the discovery of the Taung Child, there have been numerous Australopithecine discoveries from the region known as \u201cThe Cradle of Humankind,\u201d which was recently given UNESCO World Heritage Site status as \u201cThe Fossil Hominid Sites of South Africa.\u201d The limestone caves found in the Cradle allow for the excellent preservation of fossils. Past animals navigating the landscape and falling into cave openings, or caves used as dens by carnivores, led to the accumulation of deposits over millions of years. Many of the hominin fossils, encased in <strong>breccia<\/strong> (hard, calcareous sedimentary rock), are recently exposed from limestone quarries mined in the previous century. This means that extracting fossils requires excellent and detailed exposed work, often by a team of skilled technicians.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">While these sites have historically been difficult to date, with mixed assemblages accumulated over large time periods, advances in techniques such as uranium-series dating have allowed for greater accuracy. Historically, the excellent faunal record from East Africa has been used to compare sites based on <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1129\">relative dating<\/a><\/strong>, whereby environmental and faunal changes and extinction events allow us to know which hominin finds are relatively younger or older than others.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">The discovery of the Taung Child in 1924 (discussed in the Special Topic box \u201cThe Taung Child\u201d below) shifted the focus of palaeoanthropological research from Europe to Africa, although acceptance of this shift was slow (Broom 1947; Dart 1925). The species to which it is assigned, <strong><em>Australopithecus africanus<\/em><\/strong> (name meaning \u201cSouthern Ape of Africa\u201d), is currently dated to between 3.3 mya and 2.1 mya (Pickering and Kramers 2010), with discoveries from Sterkfontein, Taung, Makapansgat, and Gladysvale in South Africa (Figure 10.18). A relatively large brain (400 cc to 500 cc), small canines without an associated diastema, and more rounded cranium and smaller teeth than <em>Au. afarensis<\/em> indicate some derived traits. Similarly, the postcranial remains (in particular, the pelvis) indicate bipedalism. However, the sloping face and curved phalanges (indicative of retained arboreal locomotor abilities) show some ancestral features. Although not in direct association with stone tools, a 2015 study noted that the trabecular bone morphology of the hand was consistent with forceful tool manufacture and use, suggesting potential early tool abilities.<\/span><\/p>\n<figure style=\"width: 570px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image19-1.png\" alt=\"A life-like reconstruction of the face of Australopithecus africanus, smiling in anterior view.\" width=\"570\" height=\"570\" \/><figcaption class=\"wp-caption-text\">Figure 10.18: An artistic reconstruction of Australopithecus africanus by John Gurche. Credit: <a href=\"https:\/\/humanorigins.si.edu\/multimedia\/slideshows\/reconstructed-faces\" target=\"_blank\">Australopithecus africanus. Reconstruction based on STS 5 by John Gurche <\/a>by <a href=\"https:\/\/www.si.edu\/\" target=\"_blank\">the Smithsonian<\/a> [exhibit: \u201cReconstructed Faces: What Does It Mean to Be Human?] is <a href=\"https:\/\/www.si.edu\/termsofuse\/\" target=\"_blank\">copyrighted and used for educational and noncommercial purposes as outlined by the Smithsonian<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Another famous <em>Au. africanus<\/em> skull (the skull of \u201cMrs. Ples\u201d) was previously attributed to <em>Plesianthropus transvaalensis<\/em><em>, <\/em>meaning \u201cnear human from the Transvaal,\u201d the old name for Gauteng Province, South Africa (Broom 1947, 1950). The name was shortened by contemporary journalists to \u201cPles\u201d (Figure 10.19). Due to the prevailing mores of the time, the assumed female found herself married, at least in name, and has become widely known as \u201cMrs. Ples.\u201d It was later reassigned to <em>Au. africanus<\/em> and is now argued by some to be a young male rather than an adult female cranium (Thackeray 2000, Thackeray et al. 2002).<\/span><\/p>\n<figure id=\"attachment_304-5\" aria-describedby=\"caption-attachment-304-5\" style=\"width: 548px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-297 \" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/9.17.jpg\" alt=\"Four views of an ancient skull are shown on a black background.\" width=\"548\" height=\"548\" \/><figcaption id=\"caption-attachment-304-5\" class=\"wp-caption-text\">Figure 10.19: The \u201cMrs. Ples\u201d brain case is small in size (like apes) but its face is less prognathic; its foramen magnum is positioned more like a modern human than an African apes. Credit: a. <a href=\"https:\/\/efossils.org\/page\/boneviewer\/Australopithecus%20africanus\/Sts%205\" target=\"_blank\">Australopithecus africanus Sts 5 anterior view<\/a> by \u00a9<a href=\"https:\/\/www.efossils.org\/\" target=\"_blank\">eFossils<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\" target=\"_blank\">CC BY-NC-SA 2.0 License<\/a> and is <a href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\" target=\"_blank\">used as outlined by eFossils<\/a>; b. <a href=\"https:\/\/efossils.org\/page\/boneviewer\/Australopithecus%20africanus\/Sts%205\" target=\"_blank\">Australopithecus africanus Sts 5 posterior view<\/a> by \u00a9<a href=\"https:\/\/www.efossils.org\/\" target=\"_blank\">eFossils<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\" target=\"_blank\">CC BY-NC-SA 2.0 License<\/a> and is <a href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\" target=\"_blank\">used as outlined by eFossils<\/a>; c. <a href=\"https:\/\/efossils.org\/page\/boneviewer\/Australopithecus%20africanus\/Sts%205\" target=\"_blank\">Australopithecus africanus Sts 5 superior view<\/a> by \u00a9<a href=\"https:\/\/www.efossils.org\/\" target=\"_blank\">eFossils<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\" target=\"_blank\">CC BY-NC-SA 2.0 License<\/a> and is <a href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\" target=\"_blank\">used as outlined by eFossils<\/a>; and d. <a href=\"https:\/\/efossils.org\/page\/boneviewer\/Australopithecus%20africanus\/Sts%205\" target=\"_blank\">Australopithecus africanus Sts 5 lateral right view<\/a> by \u00a9<a href=\"https:\/\/www.efossils.org\/\" target=\"_blank\">eFossils<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\" target=\"_blank\">CC BY-NC-SA 2.0 License<\/a> and is <a href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\" target=\"_blank\">used as outlined by eFossils<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">In 2008, nine-year-old Matthew Berger, son of paleoanthropologist Lee Berger, noted a clavicle bone in some leftover mining breccia in the Malapa Fossil Site (South Africa). After rigorous studies, the species, <strong><em>Australopithecus sediba<\/em><\/strong> (meaning \u201cfountain\u201d or \u201cwellspring\u201d in the South African language of Sesotho), was named in 2010 (Figure 10.20; Berger et al. 2010). The first type specimen belongs to a juvenile male, Karabo (MH1), but the species is known from at least six partial skeletons, from infants through adults. These specimens are currently dated to 1.97 mya (Dirks et al. 2010). The discoverers have argued that <em>Au. sediba<\/em> shows mosaic features between <em>Au. africanus<\/em> and the genus, <em>Homo<\/em>, which potentially indicates a transitional species, although this is heavily debated. These features include a small brain size (<em>Australopithecus<\/em>-like; 420 cc to 450 cc) but gracile mandible and small teeth (<em>Homo<\/em>-like). Similarly, the postcranial skeletons are also said to have mosaic features: scientists have interpreted this mixture of traits (such as a robust ankle but evidence for an arch in the foot) as a transitional phase between a body previously adapted to arborealism (particularly in evidence from the bones of the wrist) to one that adapted to bipedal ground walking. Some researchers have argued that <em>Au. sediba<\/em> shows a modern hand morphology (shorter fingers and a longer thumb), indicating that adaptations to tool manufacture and use may be present in this species.<\/span><\/p>\n<figure style=\"width: 531px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image17-1.png\" alt=\"A beige-colored skull with no mandible on a black background has some missing teeth.\" width=\"531\" height=\"400\" \/><figcaption class=\"wp-caption-text\">Figure 10.20: Australopithecus sediba shows mosaic features between Au. africanus and Homo. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Australopithecus_sediba.JPG\" target=\"_blank\">Australopithecus sediba<\/a>, photo by Brett Eloff courtesy <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Profberger\" target=\"_blank\">Profberger<\/a> and <a href=\"https:\/\/en.wikipedia.org\/wiki\/University_of_the_Witwatersrand\" target=\"_blank\">Wits University<\/a>, is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\" target=\"_blank\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Another famous Australopithecine find from South Africa is that of the nearly complete skeleton now known as \u201cLittle Foot\u201d (Clarke 1998, 2013). Little Foot (StW 573) is potentially the earliest dated South African hominin fossil, dating to 3.7 mya, based on radiostopic techniques, although some argue that it is younger than 3 mya (Pickering and Kramers 2010). The name is jokingly in contrast to the cryptid species \u201cbigfoot\u201d and is named because the initial discovery of four ankle bones indicated bipedality. Little Foot was discovered by Ron Clarke in 1994, when he came across the ankle bones while sorting through monkey fossils in the University of Witwatersrand collections (Clarke and Tobias 1995). He asked Stephen Motsumi and Nkwane Molefe to identify the known records of the fossils, which allowed them to find the rest of the specimen within just days of searching the Sterkfontein Caves\u2019 Silberberg Grotto.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">The discoverers of Little Foot insist that other fossil finds, previously identified as <em>Au. Africanus<\/em>, be placed in this new species based on shared ancestral traits with older East African Australopithecines (Clarke and Kuman 2019). These include features such as a relatively large brain size (408 cc), robust zygomatic arch, and a flatter midface. Furthermore, the discoverers have argued that the heavy anterior dental wear patterns, relatively large anterior dentition, and smaller hind dentition of this specimen more closely resemble that of <em>Au. anamensis<\/em> or <em>Au. afarensis<\/em>. It has thus been placed in the species <strong><em>Australopithecus prometheus<\/em><\/strong>. This species name refers to a previously defunct taxon named by Raymond Dart. The species designation was, through analyzing Little Foot, revived by Ron Clarke, who insists that many other fossil hominin specimens have prematurely been placed into <em>Au. africanus<\/em>. Others say that it is more likely that <em>Au. africanus<\/em> is a more variable species and not representative of two distinct species.<\/span><\/p>\n<h3 class=\"import-Normal\"><strong><span style=\"color: #000000\"><em>Paranthropus<\/em> \u201cRobust\u201d Australopithecines<\/span><\/strong><\/h3>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">In the robust australopithecines, the specialized nature of the teeth and masticatory system, such as flaring zygomatic arches (cheekbones), accommodate very large temporalis (chewing) muscles. These features also include a large, broad, dish-shaped face and and a large mandible with extremely large posterior dentition (referred to as megadonts) and hyper-thick enamel (Kimbel 2015; Lee-Thorp 2011; Wood 2010). Research has revolved around the shared adaptations of these \u201crobust\u201d australopithecines, linking their morphologies to a diet of hard and\/or tough foods (Brain 1967; Rak 1988). Some argued that the diet of the robust australopithecines was so specific that any change in environment would have accelerated their extinction. The generalist nature of the teeth of the gracile australopithecines, and of early <em>Homo<\/em>, would have made them more capable of adapting to environmental change. However, some have suggested that the features of the robust australopithecines might have developed as an effective response to what are known as <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1376\">fallback foods<\/a><\/strong> in hard times rather than indicating a lack of adaptability.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">There are currently three widely accepted robust australopithecus or, <em>Paranthropus<\/em>, species: <em>P. aethiopic<\/em><em>us<\/em>, which has more ancestral traits, and <em>P. boisei and P. robustus<\/em>, which are more derived in their features (Strait et al. 1997; Wood and Schroer 2017). These three species have been grouped together by a majority of scholars as a single genus as they share more derived features (are more closely related to each other; or, in other words, are <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1377\">monophyletic<\/a><\/strong>) than the other australopithecines (Grine 1988; Hlazo 2015; Strait et al. 1997; Wood 2010 ). While researchers have mostly agreed to use the umbrella term <em>Paranthropus<\/em>, there are those who disagree (Constantino and Wood 2004, 2007; Wood 2010).<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">As a collective, this genus spans 2.7 mya to 1.0 mya, although the dates of the individual species differ. The earliest of the Paranthropus species, <strong><em>Paranthropus aethiopicus<\/em><\/strong>, is dated to between 2.7 mya and 2.3 mya and currently found in Tanzania, Kenya, and Ethiopia in the EARS system (Figure 10.21; Constantino and Wood 2007; Hlazo 2015; Kimbel 2015; Walker et al. 1986; White 1988). It is well known because of one specimen known as the \u201cBlack Skull\u201d (KNM\u2013WT 17000), so called because of the mineral manganese that stained it black during fossilization (Kimbel 2015). As with all robust Australopithecines, <em>P. aethiopicus<\/em> has the shared derived traits of large, flat premolars and molars; large, flaring zygomatic arches for accommodating large chewing muscles (the temporalis muscle); a sagittal crest (ridge on the top of the skull) for increased muscle attachment of the chewing muscles to the skull; and a robust mandible and supraorbital torus (brow ridge). However, only a few teeth have been found. A proximal tibia indicates bipedality and similar body size to <em>Au. afarensis<\/em>. In recent years, researchers have discovered and assigned a proximal tibia and juvenile cranium (L.338y-6) to the species (Wood and Boyle 2016).<\/span><\/p>\n<figure id=\"attachment_304-6\" aria-describedby=\"caption-attachment-304-6\" style=\"width: 666px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-299 \" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/9.19.jpg\" alt=\"Five views of a beige partial skull on a black background.\" width=\"666\" height=\"444\" \/><figcaption id=\"caption-attachment-304-6\" class=\"wp-caption-text\">Figure 10.21: The \u201cBlack Skull\u201d (Paranthropus aethiopicus) had a large sagittal crest and large, flared zygomatic arches that indicate it had large chewing muscles and a powerful biting force. Credit: a. <a class=\"rId156\" href=\"https:\/\/efossils.org\/page\/boneviewer\/paranthropus%20aethiopicus\/KNM-WT%2017000\" target=\"_blank\"><em>Paranthropus aethiopicus<\/em><\/a><a class=\"rId157\" href=\"https:\/\/efossils.org\/page\/boneviewer\/paranthropus%20aethiopicus\/KNM-WT%2017000\">: KNM-WT 17000 anterior view<\/a> by \u00a9<a class=\"rId158\" href=\"https:\/\/www.efossils.org\/\" target=\"_blank\">eFossils<\/a> is under a <a class=\"rId159\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\" target=\"_blank\">CC BY-NC-SA 2.0 License<\/a> and is <a class=\"rId160\" href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\" target=\"_blank\">used as outlined by eFossils<\/a>; b. <a class=\"rId161\" href=\"https:\/\/efossils.org\/page\/boneviewer\/paranthropus%20aethiopicus\/KNM-WT%2017000\" target=\"_blank\"><em>Paranthropus aethiopicus<\/em><\/a><a class=\"rId162\" href=\"https:\/\/efossils.org\/page\/boneviewer\/paranthropus%20aethiopicus\/KNM-WT%2017000\" target=\"_blank\">: KNM-WT 17000 lateral right view<\/a> by \u00a9<a class=\"rId163\" href=\"https:\/\/www.efossils.org\/\" target=\"_blank\">eFossils<\/a> is under a <a class=\"rId164\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\" target=\"_blank\">CC BY-NC-SA 2.0 License<\/a> and is <a class=\"rId165\" href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\" target=\"_blank\">used as outlined by eFossils<\/a>; c. <a class=\"rId166\" href=\"https:\/\/efossils.org\/page\/boneviewer\/paranthropus%20aethiopicus\/KNM-WT%2017000\" target=\"_blank\"><em>Paranthropus aethiopicus<\/em><\/a><a class=\"rId167\" href=\"https:\/\/efossils.org\/page\/boneviewer\/paranthropus%20aethiopicus\/KNM-WT%2017000\" target=\"_blank\">: KNM-WT 17000 superior view<\/a> by \u00a9<a class=\"rId168\" href=\"https:\/\/www.efossils.org\/\" target=\"_blank\">eFossils<\/a> is under a <a class=\"rId169\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\" target=\"_blank\">CC BY-NC-SA 2.0 License<\/a> and is <a class=\"rId170\" href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\" target=\"_blank\">used as outlined by eFossils<\/a>; d. <a class=\"rId171\" href=\"https:\/\/efossils.org\/page\/boneviewer\/paranthropus%20aethiopicus\/KNM-WT%2017000\" target=\"_blank\"><em>Paranthropus aethiopicus<\/em><\/a><a class=\"rId172\" href=\"https:\/\/efossils.org\/page\/boneviewer\/paranthropus%20aethiopicus\/KNM-WT%2017000\" target=\"_blank\">: KNM-WT 17000 posterior view<\/a> by \u00a9<a class=\"rId173\" href=\"https:\/\/www.efossils.org\/\" target=\"_blank\">eFossils<\/a> is under a <a class=\"rId174\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\" target=\"_blank\">CC BY-NC-SA 2.0 License<\/a> and is <a class=\"rId175\" href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\" target=\"_blank\">used as outlined by eFossils<\/a>; e. <a class=\"rId176\" href=\"https:\/\/efossils.org\/page\/boneviewer\/paranthropus%20aethiopicus\/KNM-WT%2017000\" target=\"_blank\"><em>Paranthropus aethiopicus<\/em><\/a><a class=\"rId177\" href=\"https:\/\/efossils.org\/page\/boneviewer\/paranthropus%20aethiopicus\/KNM-WT%2017000\" target=\"_blank\">: KNM-WT 17000 inferior view<\/a> by \u00a9<a class=\"rId178\" href=\"https:\/\/www.efossils.org\/\" target=\"_blank\">eFossils<\/a> is under a <a class=\"rId179\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\" target=\"_blank\">CC BY-NC-SA 2.0 License<\/a> and is <a class=\"rId180\" href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\" target=\"_blank\">used as outlined by eFossils<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">First attributed as <em>Zinjanthropus boisei<\/em> (with the first discovery going by the nickname \u201cZinj\u201d or sometimes \u201cNutcracker Man\u201d), <strong><em>Paranthropus boisei<\/em><\/strong> was discovered in 1959 by Mary Leakey (see Figure 10.22 and 10.23; Hay 1990; Leakey 1959). This \u201crobust\u201d australopith species is distributed across countries in East Africa at sites such as Kenya (Koobi Fora, West Turkana, and Chesowanja), Malawi (Malema-Chiwondo), Tanzania (Olduvai Gorge and Peninj), and Ethiopia (Omo River Basin and Konso). The <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1378\">hypodigm<\/a><\/strong>, sample of fossils whose features define the group, has been found by researchers to date to roughly 2.4 mya to 1.4 mya. Due to the nature of its exaggerated, larger, and more robust features, <em>P. boisei <\/em>has been termed <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1379\">hyper-robust<\/a><\/strong>\u2014that is, even more heavily built than other robust species, with very large, flat posterior dentition (Kimbel 2015). Tools dated to 2.5 mya in Ethiopia have been argued to possibly belong to this species. Despite the cranial features of <em>P. boisei<\/em> indicating a tough diet of tubers, nuts, and seeds, isotopes indicate a diet high in C4 foods (e.g., grasses, such as sedges). Another famous specimen from this species is the Peninj mandible from Tanzania, found in 1964 by Kimoya Kimeu.<\/span><\/p>\n<figure style=\"width: 557px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image14-1.png\" alt=\"Life-like reconstruction of Paranthropus boisei.\" width=\"557\" height=\"557\" \/><figcaption class=\"wp-caption-text\">Figure 10.22: Artistic reconstruction of a Paranthropus boisei, male, by John Gurche. Credit: <a href=\"https:\/\/humanorigins.si.edu\/multimedia\/slideshows\/reconstructed-faces\" target=\"_blank\">Paranthropus boisei, male. Reconstruction based on OH 5 and KNM-ER 406 by John Gurche<\/a> by <a href=\"https:\/\/www.si.edu\/\" target=\"_blank\">the Smithsonian<\/a> [exhibit: \u201cReconstructed Faces: What Does It Mean to Be Human?\u201d] is <a href=\"https:\/\/www.si.edu\/termsofuse\/\" target=\"_blank\">copyrighted and used for educational and noncommercial purposes as outlined by the Smithsonian<\/a>.<\/figcaption><\/figure>\n<figure id=\"attachment_304-7\" aria-describedby=\"caption-attachment-304-7\" style=\"width: 565px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-301 \" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/9.21.jpg\" alt=\"Three views of an ancient skull are shown on a black background.\" width=\"565\" height=\"565\" \/><figcaption id=\"caption-attachment-304-7\" class=\"wp-caption-text\">Figure 10.23: \u201cNutcracker Man\u201d (Paranthropus boisei) had hyper-robust features including very large dentition, flaring zygomatic arches, a broad concave face. It had a powerful and extremely efficient chewing force. Credit: <a href=\"https:\/\/efossils.org\/page\/boneviewer\/Paranthropus%20boisei\/OH%205\" target=\"_blank\">Paranthropus boisei: OH 5 anterior view<\/a> by \u00a9<a href=\"https:\/\/www.efossils.org\/\" target=\"_blank\">eFossils<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\" target=\"_blank\">CC BY-NC-SA 2.0 License<\/a> and is <a href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\" target=\"_blank\">used as outlined by eFossils<\/a>; b. <a href=\"https:\/\/efossils.org\/page\/boneviewer\/Paranthropus%20boisei\/OH%205\" target=\"_blank\">Paranthropus boisei: OH 5 inferior view<\/a> by \u00a9<a href=\"https:\/\/www.efossils.org\/\" target=\"_blank\">eFossils<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\" target=\"_blank\">CC BY-NC-SA 2.0 License<\/a> and is <a href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\" target=\"_blank\">used as outlined by eFossils<\/a>; c. <a href=\"https:\/\/efossils.org\/page\/boneviewer\/Paranthropus%20boisei\/OH%205\" target=\"_blank\">Paranthropus boisei: OH 5 posterior view<\/a> by \u00a9<a href=\"https:\/\/www.efossils.org\/\" target=\"_blank\">eFossils<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\" target=\"_blank\">CC BY-NC-SA 2.0 License<\/a> and is <a href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\" target=\"_blank\">used as outlined by eFossils<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong><em>Paranthropus robustus<\/em><\/strong> was the first taxon to be discovered within the genus in Kromdraai B by a schoolboy named Gert Terblanche; subsequent fossil discoveries were made by researcher Robert Broom in 1938 (Figure 10.24; Broom 1938a, 1938b, 1950), with the holotype specimen TM 1517 (Broom 1938a, 1938b, 1950; Hlazo 2018). <em>Paranthropus robustus<\/em> dates approximately from 2.0 mya to 1 mya and is the only taxon from the genus to be discovered in South Africa. Several of these fossils are fragmentary in nature, distorted, and not well preserved because they have been recovered from quarry breccia using explosives. <em>P. robustus<\/em> features are neither as \u201chyper-robust\u201d as <em>P. boisei<\/em> nor as ancestral as <em>P. aethiopicus<\/em>; instead, they have been described as being less derived, more general features that are shared with both East African species (e.g., the sagittal crest and zygomatic flaring; Rak 1983; Walker and Leakey 1988). Enamel hypoplasia is also common in this species, possibly because of instability in the development of large, thick-enameled dentition.<\/span><\/p>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_304-8\" aria-describedby=\"caption-attachment-304-8\" style=\"width: 572px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-302 \" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/9.22.jpg\" alt=\"Four views of a beige-colored skull are shown on a black background.\" width=\"572\" height=\"619\" \/><figcaption id=\"caption-attachment-304-8\" class=\"wp-caption-text\">Figure 10.24: SK 48, a Paranthropus robustus specimen, had less derived, more general features that were not as robust as P. boisei and not as ancestral as P. aethiopicus. Credit: a. <a class=\"rId208\" href=\"https:\/\/efossils.org\/page\/boneviewer\/Paranthropus%20robustus\/SK%2048\" target=\"_blank\"><em>Paranthropus robustus<\/em><\/a><a class=\"rId209\" href=\"https:\/\/efossils.org\/page\/boneviewer\/Paranthropus%20robustus\/SK%2048\" target=\"_blank\">: SK 48 anterior view<\/a> by \u00a9<a class=\"rId210\" href=\"https:\/\/www.efossils.org\/\" target=\"_blank\">eFossils<\/a> is under a <a class=\"rId211\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\" target=\"_blank\">CC BY-NC-SA 2.0 License<\/a> and is <a class=\"rId212\" href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\" target=\"_blank\">used as outlined by eFossils<\/a>; b. <a class=\"rId213\" href=\"https:\/\/efossils.org\/page\/boneviewer\/Paranthropus%20robustus\/SK%2048\" target=\"_blank\"><em>Paranthropus robustus<\/em><\/a><a class=\"rId214\" href=\"https:\/\/efossils.org\/page\/boneviewer\/Paranthropus%20robustus\/SK%2048\" target=\"_blank\">: SK 48 superior view<\/a> by \u00a9<a class=\"rId215\" href=\"https:\/\/www.efossils.org\/\" target=\"_blank\">eFossils<\/a> is under a <a class=\"rId216\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\" target=\"_blank\">CC BY-NC-SA 2.0 License<\/a> and is <a class=\"rId217\" href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\" target=\"_blank\">used as outlined by eFossils<\/a>; c. <a class=\"rId218\" href=\"https:\/\/efossils.org\/page\/boneviewer\/Paranthropus%20robustus\/SK%2048\" target=\"_blank\"><em>Paranthropus robustus<\/em><\/a><a class=\"rId219\" href=\"https:\/\/efossils.org\/page\/boneviewer\/Paranthropus%20robustus\/SK%2048\" target=\"_blank\">: SK 48 inferior view<\/a> by \u00a9<a class=\"rId220\" href=\"https:\/\/www.efossils.org\/\" target=\"_blank\">eFossils<\/a> is under a <a class=\"rId221\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\" target=\"_blank\">CC BY-NC-SA 2.0 License<\/a> and is <a class=\"rId222\" href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\" target=\"_blank\">used as outlined by eFossils<\/a>; d. <a class=\"rId223\" href=\"https:\/\/efossils.org\/page\/boneviewer\/Paranthropus%20robustus\/SK%2048\" target=\"_blank\"><em>Paranthropus robustus<\/em><\/a><a class=\"rId224\" href=\"https:\/\/efossils.org\/page\/boneviewer\/Paranthropus%20robustus\/SK%2048\" target=\"_blank\">: SK 48 lateral left view<\/a> by \u00a9<a class=\"rId225\" href=\"https:\/\/www.efossils.org\/\" target=\"_blank\">eFossils<\/a> is under a <a class=\"rId226\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\" target=\"_blank\">CC BY-NC-SA 2.0 License<\/a> and is <a class=\"rId227\" href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\" target=\"_blank\">used as outlined by eFossils<\/a>.<\/figcaption><\/figure>\n<h3 class=\"import-Normal\"><strong><span style=\"color: #000000\">Comparisons between Gracile and Robust Australopiths<\/span><\/strong><\/h3>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Comparisons between gracile and robust australopithecines may indicate different phylogenetic groupings or parallel evolution in several species. In general, the robust australopithecines have large temporalis (chewing) muscles, as indicated by flaring zygomatic arches, sagittal crests, and robust mandibles (jawbones). Their hind dentition is large (megadont), with low cusps and thick enamel. Within the gracile australopithecines, researchers have debated the relatedness of the species, or even whether these species should be lumped together to represent more variable or polytypic species. Often researchers will attempt to draw chronospecific trajectories, with one taxon said to evolve into another over time.<\/span><\/p>\n<div class=\"textbox\">\n<h2 class=\"import-Normal\"><span style=\"color: #000000\">Special Topic: The Taung Child<\/span><\/h2>\n<figure id=\"attachment_303\" aria-describedby=\"caption-attachment-303\" style=\"width: 570px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-303 \" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/9.23.jpg\" alt=\"An ancient skull in anterior and lateral views. One view shows an imprint of the brain.\" width=\"570\" height=\"285\" \/><figcaption id=\"caption-attachment-303\" class=\"wp-caption-text\">Figure 10.25: The Taung Child has a nearly complete face, mandible, and partial endocranial cast. Credit: a. <em>A<\/em><a class=\"rId230\" href=\"https:\/\/efossils.org\/page\/boneviewer\/Australopithecus%20africanus\/Taung%201\" target=\"_blank\"><em>ustralopithecus africanus<\/em><\/a><a class=\"rId231\" href=\"https:\/\/efossils.org\/page\/boneviewer\/Australopithecus%20africanus\/Taung%201\" target=\"_blank\">: Taung 1 anterior view<\/a> by \u00a9<a class=\"rId232\" href=\"https:\/\/www.efossils.org\/\" target=\"_blank\">eFossils<\/a> is under a <a class=\"rId233\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\" target=\"_blank\">CC BY-NC-SA 2.0 License<\/a> and is <a class=\"rId234\" href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\" target=\"_blank\">used as outlined by eFossils<\/a>; b. <a class=\"rId235\" href=\"https:\/\/efossils.org\/page\/boneviewer\/Australopithecus%20africanus\/Taung%201\" target=\"_blank\"><em>australopithecus africanus<\/em><\/a><a class=\"rId236\" href=\"https:\/\/efossils.org\/page\/boneviewer\/Australopithecus%20africanus\/Taung%201\" target=\"_blank\">: Taung 1 lateral right view<\/a> by \u00a9<a class=\"rId237\" href=\"https:\/\/www.efossils.org\/\" target=\"_blank\">eFossils<\/a> is under a <a class=\"rId238\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\" target=\"_blank\">CC BY-NC-SA 2.0 License<\/a> and is <a class=\"rId239\" href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\" target=\"_blank\">used as outlined by eFossils<\/a>.<\/figcaption><\/figure>\n<p><span style=\"color: #000000\">The well-known fossil of a juvenile <em>Australopithecine<\/em>, the \u201cTaung Child,\u201d was the first early hominin evidence ever discovered and was the first to demonstrate our common human heritage in Africa (Figure 10.25; Dart 1925). The tiny facial skeleton and natural endocast were discovered in 1924 by a local quarryman in the North West Province in South Africa and were painstakingly removed from the surrounding cement-like breccia by Raymond Dart using his wife\u2019s knitting needles. When first shared with the scientific community in 1925, it was discounted as being nothing more than a young monkey of some kind. Prevailing biases of the time made it too difficult to contemplate that this small-brained hominin could have anything to do with our own history. The fact that it was discovered in Africa simply served to strengthen this bias.<\/span><\/p>\n<\/div>\n<h2><span style=\"color: #000000\">Early Tool Use and Technology<br \/>\n<\/span><\/h2>\n<h3 class=\"import-Normal\"><strong><span style=\"color: #000000\">Early Stone Age Technology (ESA)<\/span><\/strong><\/h3>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">The <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1380\">Early Stone Age (ESA)<\/a><\/strong> marks the beginning of recognizable technology made by our human ancestors. Stone-tool (or <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1381\">lithic<\/a><\/strong>) technology is defined by the fracturing of rocks and the manufacture of tools through a process called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1382\">knapping<\/a><\/strong>. The Stone Age lasted for more than 3 million years and is broken up into chronological periods called the Early (ESA), Middle (MSA), and Later Stone Ages (LSA). Each period is further broken up into a different <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1383\">techno-complex<\/a><\/strong>, a term encompassing multiple <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1384\">assemblages<\/a><\/strong> (collections of artifacts) that share similar traits in terms of artifact production and morphology. The ESA spanned the largest technological time period of human innovation from over 3 million years ago to around 300,000 years ago and is associated almost entirely with hominin species prior to modern <em>Homo sapiens. <\/em>As the ESA advanced, stone tool makers (known as <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1386\">knappers<\/a><\/strong>) began to change the ways they detached <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1385\">flakes<\/a><\/strong> and eventually were able to shape artifacts into functional tools. These advances in technology go together with the developments in human evolution and cognition, dispersal of populations across the African continent and the world, and climatic changes.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">In order to understand the ESA, it is important to consider that not all assemblages are exactly the same within each techno-complex: one can have multiple phases and traditions at different sites (Lombard et al. 2012). However, there is an overarching commonality between them. Within stone tool assemblages, both flakes or <strong>cores<\/strong> (the rocks from which flakes are removed) are used as tools. <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1387\">Large Cutting Tools (LCTs) <\/a><\/strong> are tools that are shaped to have functional edges. It is important to note that the information presented here is a small fraction of what is known about the ESA, and there are ongoing debates and discoveries within archaeology.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Currently, the oldest-known stone tools, which form the techno-complex the Lomekwian, date to 3.3 mya (Harmand et al. 2015; Toth 1985). They were found at a site called Lomekwi 3 in Kenya. This techno-complex is the most recently defined and pushed back the oldest-known date for lithic technology. There is only one known site thus far and, due to the age of the site, it is associated with species prior to <em>Homo<\/em>, such as <em>Kenyanthropus platyops.<\/em> Flakes were produced through indirect percussion, whereby the knappers held a rock and hit it against another rock resting on the ground. The pieces are very chunky and do not display the same fracture patterns seen in later techno-complexes. Lomekwian knappers likely aimed to get a sharp-edged piece on a flake, which would have been functional, although the specific function is currently unknown.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Stone tool use, however, is not only understood through the direct discovery of the tools. Cut marks on fossilized animal bones may illuminate the functionality of stone tools. In one controversial study in 2010, researchers argued that cut marks on a pair of animal bones from Dikika (Ethiopia), dated to 3.4 mya, were from stone tools. The discoverers suggested that they be more securely associated, temporally, with <em>Au. afarensis<\/em>. However, others have noted that these marks are consistent with teeth marks from crocodiles and other carnivores.<\/span><\/p>\n<figure style=\"width: 324px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image29-1.png\" alt=\"A technical line drawing of an Oldowan chopper.\" width=\"324\" height=\"275\" \/><figcaption class=\"wp-caption-text\">Figure 10.26: Some scholars believe that some genera explored in this chapter were capable of producing more complex stone tools (Oldowan). Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Olduwan_Industry_Chopper_2.jpeg\" target=\"_blank\">Olduwan Industry Chopper 2<\/a> by Emmyanne29 is under a <a href=\"https:\/\/creativecommons.org\/publicdomain\/zero\/1.0\/legalcode\" target=\"_blank\">CC0 1.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">The Oldowan techno-complex is far more established in the scientific literature (Leakey 1971). It is called the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1388\">Oldowan<\/a><\/strong> because it was originally discovered in Olduvai Gorge, Tanzania, but the oldest assemblage is from Gona in Ethiopia, dated to 2.6 mya (Semaw 2000). The techno-complex is defined as a core and flake industry. Like the Lomekwian, there was an aim to get sharp-edged flakes, but this was achieved through a different production method. Knappers were able to actively hold or manipulate the core being knapped, which they could directly hit using a hammerstone. This technique is known as free-hand percussion, and it demonstrates an understanding of fracture mechanics. It has long been argued that the Oldowan hominins were skillful in tool manufacture.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Because Oldowan knapping requires skill, earlier researchers have attributed these tools to members of our genus, <em>Homo<\/em>. However, some have argued that these tools are in more direct association with hominins in the genera described in this chapter (Figure 10.26).<\/span><\/p>\n<h3 class=\"import-Normal\"><strong><span style=\"color: #000000\">Invisible Tool Manufacture and Use<\/span><\/strong><\/h3>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">The vast majority of our understanding of these early hominins comes from fossils and reconstructed paleoenvironments. It is only from 3 mya when we can start \u201clooking into their minds\u201d and lifestyles by analyzing their manufacture and use of stone tools. However, the vast majority of tool use in primates (and, one can argue, in humans) is not with durable materials like stone. All of our extant great ape relatives have been observed using sticks, leaves, and other materials for some secondary purpose (to wade across rivers, to \u201cfish\u201d for termites, or to absorb water for drinking). It is possible that the majority of early hominin tool use and manufacture may be invisible to us because of this preservation bias.<\/span><\/p>\n<h2>Cultural Connections and Contemporary Implications<\/h2>\n<p>Evolutionary theories of bipedalism continue to be widely debated. As discussed above, numerous (~30) hypotheses have been proposed to explain why early hominins began walking on two legs. Some remain dominant in the field, while others have been challenged or refined over time. For instance, the <strong>Savannah Hypothesis<\/strong>, which proposed that bipedalism emerged as an adaptation to open grassland environments, has been contested by the <strong>Shore Dweller Hypothesis<\/strong>. Increasing fossil evidence suggests that early hominins may have lived near rivers and wetlands, rather than exclusively in savannahs. This indicates that bipedalism evolved not in hot, dry environments, but rather in more humid, forested regions, where mobility across varied terrain offered selective advantages.<\/p>\n<p>Across these different perspectives, researchers have proposed both biological and cultural explanations for the origins of bipedalism. Lovejoy\u2019s <strong>Male Provisioning Hypothesis,<\/strong> for example, argues that bipedalism developed as males began carrying resources, such as food, to dependent females and offspring. Similarly, other models emphasize the importance of holding and hunting, suggesting that an upright posture freed the arms to transport tools and other objects, which could then be crafted and used more efficiently.<\/p>\n<p>One explanation related to humid forest environments is Niemitz\u2019s <strong>Amphibian Generalist Theory<\/strong> (2010), which proposes that early hominins living near water benefited from plentiful year-round food sources. Plus, moving through water reduces body weight and joint pressure, which may have created selective pressures favouring upright locomotion. This behaviour is still observed in other primates; many adopt bipedal postures in shallow water, and some even swim!<\/p>\n<p>Beyond bipedalism, early hominins experienced a mosaic of evolutionary changes, including alterations to bones, teeth, and, notably, the brain. The brain offers crucial insights into our evolutionary history. Fossil evidence shows a gradual increase in brain size among early hominins (see next chapter on early <em>Homo<\/em>), suggesting significant biological and behavioural shifts. Because the brain is an energy-intensive organ, consuming nearly 18% of the body\u2019s energy, its expansion likely required compensatory adaptations elsewhere. One such theory, the <strong>Expensive Tissue Hypothesis <\/strong>(Aiello &amp; Wheeler, 1995), suggests that as the brain grew, the gut decreased in size to offset the brain's energy demands. This change may have been supported by dietary shifts, not only increased meat consumption (scavenging and opportunistic hunting), but also forms of food processing and the introduction of cooking, making nutrients more accessible and possibly requiring less gut processing time (Wrangham, 1999, 2009).<\/p>\n<p>Brain expansion also had profound implications for childbirth and social behaviour (Rosenberg, 1992). The pelvic modifications required for bipedalism made childbirth more difficult, possibly necessitating assistance from others, and an early form of cooperative care (Burkart et al. 2025). Furthermore, as brain size increased, the capacity for complex communication may have expanded. While nonhuman primates communicate in various ways, the growth of the human brain could have enabled the development of language, strengthening social bonds, and fostering increasingly complex cultural systems.<\/p>\n<p>In short, fossil evidence suggests that human evolution cannot be understood solely in biological terms. The emergence of bipedalism, brain expansion, and cultural behaviours are deeply interconnected, reflecting the intricate relationship between our physical evolution and the socio-cultural environments that shaped early hominins.<\/p>\n<h4>Discussion Questions<\/h4>\n<ul>\n<li>Based on the theories discussed above, what are your thoughts or opinions on the emergence of bipedalism? Has it benefited us in any way? What are some of the problems we face?<\/li>\n<li>What other cultural adaptations might have influenced our morphological features? Can we observe some of these changes today?<\/li>\n<li>Do you believe technology today is impacting our evolutionary journey? Please elaborate.<\/li>\n<\/ul>\n<h2 class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">Hominin Species Summaries<br \/>\n<\/span><\/h2>\n<div style=\"text-align: left\">\n<table style=\"width: 450pt\">\n<tbody>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Hominin<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><em>Sahelanthropus tchadensis<\/em><\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Dates<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">7 mya to 6 mya<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Region(s)<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Chad<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Famous discoveries<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 1.5pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">The initial discovery, made in 2001.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Brain <\/strong><strong>s<\/strong><strong>ize<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">360 cc average<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Dentition<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Smaller than in extant great apes; larger and pointier than in humans. Canines worn at the tips.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Cranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">A short cranial base and a foramen magnum (hole in which the spinal cord enters the cranium) that is more humanlike in positioning; has been argued to indicate upright walking.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Postcranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Currently little published postcranial material.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Culture<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">N\/A<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Other<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">The extent to which this hominin was bipedal is currently heavily debated. If so, it would indicate an arboreal bipedal ancestor of hominins, not a knuckle-walker like chimpanzees.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div style=\"text-align: left\">\n<table style=\"width: 450pt\">\n<tbody>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Hominin<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><em>Orrorin tugenensis<\/em><\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Dates<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 1.5pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">6 mya to 5.7 mya<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Region(s)<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 1.5pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Tugen Hills (Kenya)<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Famous discoveries<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 1.5pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Original discovery in 2000.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Brain <\/strong><strong>s<\/strong><strong>ize<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">N\/A<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Dentition<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Smaller cheek teeth (molars and premolars) than even more recent hominins (i.e., derived), thick enamel, and reduced, but apelike, canines.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Cranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Not many found<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Postcranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Fragmentary leg, arm, and finger bones have been found. Indicates bipedal locomotion.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Culture<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Potential toolmaking capability based on hand morphology, but nothing found directly.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Other<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">This is the earliest species that clearly indicates adaptations for bipedal locomotion.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div style=\"text-align: left\">\n<table style=\"width: 450pt\">\n<tbody>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Hominin<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><em>Ardipithecus kadabba<\/em><\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Dates<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">5.2 mya to 5.8 mya<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Region(s)<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Middle Awash (Ethiopia)<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Famous discoveries<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Discovered by Yohannes Haile-Selassie in 1997.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Brain <\/strong><strong>s<\/strong><strong>ize<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">N\/A<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Dentition<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Larger hind dentition than in modern chimpanzees. Thick enamel and larger canines than in later hominins.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Cranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">N\/A<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Postcranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">A large hallux (big toe) bone indicates a bipedal \u201cpush off.\u201d<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Culture<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">N\/A<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Other<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Faunal evidence indicates a mixed grassland\/woodland environment.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div style=\"text-align: left\">\n<table style=\"width: 450pt\">\n<tbody>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Hominin<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\"><em>Ardipithecus ramidus<\/em><\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Dates<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">4.4 mya<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Region(s)<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">Middle Awash region and Gona (Ethiopia)<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Famous discoveries<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">A partial female skeleton nicknamed \u201cArdi\u201d (ARA-VP-6\/500) (found in 1994).<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Brain size<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">300 cc to 350 cc<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Dentition<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">Little differences between the canines of males and females (small sexual dimorphism).<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Cranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">Midfacial projection, slightly prognathic. Cheekbones less flared and robust than in later hominins.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Postcranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">Ardi demonstrates a mosaic of ancestral and derived characteristics in the postcrania. For instance, an opposable big toe similar to chimpanzees (i.e., more ancestral), which could have aided in climbing trees effectively. However, the pelvis and hip show that she could walk upright (i.e., it is derived), supporting her hominin status.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Culture<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">None directly associated<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Other<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Over 110 specimens from Aramis<\/span><\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div style=\"text-align: left\">\n<table style=\"width: 450pt\">\n<tbody>\n<tr class=\"Table8-R\" style=\"height: 0\">\n<td class=\"Table8-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Hominin<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table8-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 1.5pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><em>Australopithecus anamensis<\/em><\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table8-R\" style=\"height: 0\">\n<td class=\"Table8-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Dates<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table8-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">4.2 mya to 3.8 mya<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table8-R\" style=\"height: 0\">\n<td class=\"Table8-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Region(s)<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table8-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Turkana region (Kenya); Middle Awash (Ethiopia)<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table8-R\" style=\"height: 0\">\n<td class=\"Table8-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Famous discoveries<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table8-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">A 2019 find from Ethiopia, named MRD.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table8-R\" style=\"height: 0\">\n<td class=\"Table8-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Brain <\/strong><strong>s<\/strong><strong>ize<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table8-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">370 cc<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table8-R\" style=\"height: 0\">\n<td class=\"Table8-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Dentition<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table8-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Relatively large canines compared with more recent Australopithecines.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table8-R\" style=\"height: 0\">\n<td class=\"Table8-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Cranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table8-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Projecting cheekbones and ancestral earholes.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table8-R\" style=\"height: 0\">\n<td class=\"Table8-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Postcranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table8-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Lower limb bones (tibia and femur) indicate bipedality; arboreal features in upper limb bones (humerus) found.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table8-R\" style=\"height: 0\">\n<td class=\"Table8-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Culture<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table8-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">N\/A<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table8-R\" style=\"height: 0\">\n<td class=\"Table8-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Other<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table8-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Almost 100 specimens, representing over 20 individuals, have been found to date.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div style=\"text-align: left\">\n<table style=\"width: 450pt\">\n<tbody>\n<tr class=\"Table9-R\" style=\"height: 0\">\n<td class=\"Table9-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Hominin<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table9-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><em>Australopithecus afarensis<\/em><\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table9-R\" style=\"height: 0\">\n<td class=\"Table9-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Dates<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table9-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">3.9 mya to 2.9 mya<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table9-R\" style=\"height: 0\">\n<td class=\"Table9-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Region(s)<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table9-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Afar Region, Omo, Maka, Fejej, and Belohdelie (Ethiopia); Laetoli (Tanzania); Koobi Fora (Kenya)<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table9-R\" style=\"height: 0\">\n<td class=\"Table9-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Famous discoveries<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table9-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Lucy (discovery: 1974), Selam (Dikika Child, discovery: 2000), Laetoli Footprints (discovery: 1976).<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table9-R\" style=\"height: 0\">\n<td class=\"Table9-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Brain <\/strong><strong>s<\/strong><strong>ize<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table9-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">380 cc to 430 cc<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table9-R\" style=\"height: 0\">\n<td class=\"Table9-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Dentition<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table9-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Reduced canines and molars relative to great apes but larger than in modern humans.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table9-R\" style=\"height: 0\">\n<td class=\"Table9-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Cranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table9-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Prognathic face, facial features indicate relatively strong chewing musculature (compared with <em>Homo<\/em>) but less extreme than in <em>Paranthropus<\/em>.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table9-R\" style=\"height: 0\">\n<td class=\"Table9-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Postcranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table9-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Clear evidence for bipedalism from lower limb postcranial bones. Laetoli Footprints indicate humanlike walking. Dikika Child bones indicate retained ancestral arboreal traits in the postcrania.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table9-R\" style=\"height: 0\">\n<td class=\"Table9-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Culture<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table9-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">None directly, but close in age and proximity to controversial cut marks at Dikika and early tools in Lomekwi.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table9-R\" style=\"height: 0\">\n<td class=\"Table9-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Other<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table9-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><em>Au. afarensis<\/em> is one of the oldest and most well-known australopithecine species and consists of a large number of fossil remains.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div style=\"text-align: left\">\n<table style=\"width: 450pt\">\n<tbody>\n<tr class=\"Table10-R\" style=\"height: 0\">\n<td class=\"Table10-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Hominin<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table10-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><em>Australopithecus bahrelghazali<\/em><\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table10-R\" style=\"height: 0\">\n<td class=\"Table10-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Dates<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table10-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 1.5pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">3.6 mya<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table10-R\" style=\"height: 0\">\n<td class=\"Table10-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Region(s)<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table10-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Chad<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table10-R\" style=\"height: 0\">\n<td class=\"Table10-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Famous discoveries<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table10-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">\u201cAbel,\u201d the holotype (discovery: 1995).<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table10-R\" style=\"height: 0\">\n<td class=\"Table10-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Brain <\/strong><strong>s<\/strong><strong>ize<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table10-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">N\/A<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table10-R\" style=\"height: 0\">\n<td class=\"Table10-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Dentition<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table10-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">N\/A<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table10-R\" style=\"height: 0\">\n<td class=\"Table10-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Cranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table10-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">N\/A<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table10-R\" style=\"height: 0\">\n<td class=\"Table10-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Postcranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table10-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">N\/A<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table10-R\" style=\"height: 0\">\n<td class=\"Table10-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Culture<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table10-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">N\/A<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table10-R\" style=\"height: 0\">\n<td class=\"Table10-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Other<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table10-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Arguably within range of variation of <em>Au. afarensis<\/em>.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div style=\"text-align: left\">\n<table style=\"width: 450pt\">\n<tbody>\n<tr class=\"Table11-R\" style=\"height: 0\">\n<td class=\"Table11-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Hominin<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table11-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 1.5pt;text-indent: 0pt\"><span style=\"color: #000000\"><em>Australopithecus prometheus<\/em><\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table11-R\" style=\"height: 0\">\n<td class=\"Table11-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Dates<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table11-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 1.5pt;text-indent: 0pt\"><span style=\"color: #000000\">3.7 mya (debated)<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table11-R\" style=\"height: 0\">\n<td class=\"Table11-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Region(s)<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table11-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 1.5pt;text-indent: 0pt\"><span style=\"color: #000000\">Sterkfontein (South Africa)<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table11-R\" style=\"height: 0\">\n<td class=\"Table11-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Famous discoveries<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table11-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 1.5pt;text-indent: 0pt\"><span style=\"color: #000000\">\u201cLittle Foot\u201d (StW 573) (discovery: 1994)<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table11-R\" style=\"height: 0\">\n<td class=\"Table11-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Brain size<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table11-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 1.5pt;text-indent: 0pt\"><span style=\"color: #000000\">408 cc (Little Foot estimate)<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table11-R\" style=\"height: 0\">\n<td class=\"Table11-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Dentition<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table11-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 1.5pt;text-indent: 0pt\"><span style=\"color: #000000\">Heavy anterior dental wear patterns, relatively large anterior dentition and smaller hind dentition, similar to <em>Au. afarensis<\/em>.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table11-R\" style=\"height: 0\">\n<td class=\"Table11-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Cranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table11-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 1.5pt;text-indent: 0pt\"><span style=\"color: #000000\">Relatively larger brain size, robust zygomatic arch, and a flatter midface.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table11-R\" style=\"height: 0\">\n<td class=\"Table11-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Postcranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table11-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">The initial discovery of four ankle bones indicated bipedality.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table11-R\" style=\"height: 0\">\n<td class=\"Table11-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Culture<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table11-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">N\/A<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table11-R\" style=\"height: 0\">\n<td class=\"Table11-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Other<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table11-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Highly debated new species designation.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div style=\"text-align: left\">\n<table style=\"width: 450pt\">\n<tbody>\n<tr class=\"Table12-R\" style=\"height: 0\">\n<td class=\"Table12-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Hominin<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table12-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 1.5pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><em>Australopithecus <\/em><em>deyiremada<\/em><\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table12-R\" style=\"height: 0\">\n<td class=\"Table12-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Dates<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table12-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">3.5 mya to 3.3 mya<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table12-R\" style=\"height: 0\">\n<td class=\"Table12-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Region(s)<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table12-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Woranso-Mille (Afar region, Ethiopia)<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table12-R\" style=\"height: 0\">\n<td class=\"Table12-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Famous discoveries<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table12-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 1.5pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">First fossil mandible bones were discovered in 2011 in the Afar region of Ethiopia by Yohannes Haile-Selassie.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table12-R\" style=\"height: 0\">\n<td class=\"Table12-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Brain <\/strong><strong>s<\/strong><strong>ize<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table12-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 1.5pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">N\/A<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table12-R\" style=\"height: 0\">\n<td class=\"Table12-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Dentition<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table12-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Smaller teeth with thicker enamel than seen in <em>Au. afarensis<\/em>, with a potentially hardier diet.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table12-R\" style=\"height: 0\">\n<td class=\"Table12-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Cranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table12-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Larger mandible and more projecting cheekbones than in <em>Au. afarensis<\/em>.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table12-R\" style=\"height: 0\">\n<td class=\"Table12-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Postcranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table12-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">N\/A<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table12-R\" style=\"height: 0\">\n<td class=\"Table12-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Culture<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table12-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">N\/A<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table12-R\" style=\"height: 0\">\n<td class=\"Table12-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Other<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table12-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Contested species designation; arguably a member of <em>Au. afarensis<\/em>.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div style=\"text-align: left\">\n<table style=\"width: 450pt\">\n<tbody>\n<tr class=\"Table13-R\" style=\"height: 0\">\n<td class=\"Table13-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Hominin<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table13-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\"><em>Kenyanthopus<\/em><em> platyops<\/em><\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table13-R\" style=\"height: 0\">\n<td class=\"Table13-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Dates<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table13-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">3.5 mya to 3.2 mya<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table13-R\" style=\"height: 0\">\n<td class=\"Table13-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Region(s)<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table13-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">Lake Turkana (Kenya)<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table13-R\" style=\"height: 0\">\n<td class=\"Table13-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Famous discoveries<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table13-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">KNM\u2013WT 40000 (discovered 1999)<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table13-R\" style=\"height: 0\">\n<td class=\"Table13-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Brain size<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table13-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">Difficult to determine but appears within the range of <em>Australopithecus afarensis<\/em>.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table13-R\" style=\"height: 0\">\n<td class=\"Table13-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Dentition<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table13-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">Small molars\/dentition (<em>Homo<\/em>-like characteristic)<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table13-R\" style=\"height: 0\">\n<td class=\"Table13-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Cranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table13-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">Flatter (i.e., orthognathic) face<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table13-R\" style=\"height: 0\">\n<td class=\"Table13-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Postcranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table13-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">N\/A<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table13-R\" style=\"height: 0\">\n<td class=\"Table13-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Culture<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table13-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">Some have associated the earliest tool finds from Lomekwi, Kenya, temporally (3.3 mya) and in close geographic proximity to this species\/specimen.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table13-R\" style=\"height: 0\">\n<td class=\"Table13-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Other<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table13-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">Taxonomic placing of this species is quite divided. The discoverers have argued that this species is ancestral to <em>Homo<\/em>, in particular to <em>Homo <\/em><em>ruldolfensis<\/em>.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div style=\"text-align: left\">\n<table style=\"width: 450pt\">\n<tbody>\n<tr class=\"Table14-R\" style=\"height: 0\">\n<td class=\"Table14-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Hominin<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table14-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\"><em>Australopithecus africanus<\/em><\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table14-R\" style=\"height: 0\">\n<td class=\"Table14-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Dates<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table14-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">3.3 mya to 2.1 mya<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table14-R\" style=\"height: 0\">\n<td class=\"Table14-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Region(s)<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table14-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">Sterkfontein, Taung, Makapansgat, Gladysvale (South Africa)<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table14-R\" style=\"height: 0\">\n<td class=\"Table14-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Famous discoveries<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table14-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">Taung Child (discovery in 1994), \u201cMrs. Ples\u201d (discover in 1947), Little Foot (arguable; discovery in 1994).<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table14-R\" style=\"height: 0\">\n<td class=\"Table14-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Brain size<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table14-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">400 cc to 500 cc<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table14-R\" style=\"height: 0\">\n<td class=\"Table14-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Dentition<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table14-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">Smaller teeth (derived) relative to <em>Au. afarensis<\/em>. Small canines with no diastema.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table14-R\" style=\"height: 0\">\n<td class=\"Table14-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Cranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table14-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">A rounder skull compared with <em>Au. afarensis<\/em> in East Africa. A sloping face (ancestral).<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table14-R\" style=\"height: 0\">\n<td class=\"Table14-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Postcranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table14-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">Similar postcranial evidence for bipedal locomotion (derived pelvis) with retained arboreal locomotion, e.g., curved phalanges (fingers), as seen in <em>Au. afarensis.<\/em><\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table14-R\" style=\"height: 0\">\n<td class=\"Table14-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Culture<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table14-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">None with direct evidence.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table14-R\" style=\"height: 0\">\n<td class=\"Table14-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Other<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table14-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">A 2015 study noted that the trabecular bone morphology of the hand was consistent with forceful tool manufacture and use, suggesting potential early tool abilities.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div style=\"text-align: left\">\n<table style=\"width: 450pt\">\n<tbody>\n<tr class=\"Table15-R\" style=\"height: 0\">\n<td class=\"Table15-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Hominin<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table15-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><em>Australopithecus garhi<\/em><\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table15-R\" style=\"height: 0\">\n<td class=\"Table15-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Dates<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table15-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">2.5 mya<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table15-R\" style=\"height: 0\">\n<td class=\"Table15-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Region(s)<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table15-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Middle Awash (Ethiopia)<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table15-R\" style=\"height: 0\">\n<td class=\"Table15-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Famous discoveries<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table15-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">N\/A<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table15-R\" style=\"height: 0\">\n<td class=\"Table15-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Brain <\/strong><strong>s<\/strong><strong>ize<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table15-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">450 cc<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table15-R\" style=\"height: 0\">\n<td class=\"Table15-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Dentition<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table15-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Larger hind dentition than seen in other gracile Australopithecines.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table15-R\" style=\"height: 0\">\n<td class=\"Table15-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Cranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table15-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">N\/A<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table15-R\" style=\"height: 0\">\n<td class=\"Table15-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Postcranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table15-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">A femur of a fragmentary partial skeleton, argued to belong to <em>Au. garhi<\/em>, indicates this species may be longer-limbed than <em>Au. afarensis<\/em>, although still able to move arboreally.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table15-R\" style=\"height: 0\">\n<td class=\"Table15-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Culture<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table15-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Crude stone tools resembling Oldowan (described later) have been found in association with <em>Au. garhi<\/em>.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table15-R\" style=\"height: 0\">\n<td class=\"Table15-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Other<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table15-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">This species is not well documented or understood and is based on only a few fossil specimens.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div style=\"text-align: left\">\n<table style=\"width: 450pt\">\n<tbody>\n<tr class=\"Table16-R\" style=\"height: 0\">\n<td class=\"Table16-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Hominin<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table16-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 1.5pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><em>Paranthropus aethiopicus<\/em><\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table16-R\" style=\"height: 0\">\n<td class=\"Table16-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Dates<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table16-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 1.5pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">2.7 mya to 2.3 mya<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table16-R\" style=\"height: 0\">\n<td class=\"Table16-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Region(s)<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table16-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 1.5pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">West Turkana (Kenya); Laetoli (Tanzania); Omo River Basin (Ethiopia)<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table16-R\" style=\"height: 0\">\n<td class=\"Table16-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Famous discoveries<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table16-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 1.5pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">The \u201cBlack Skull\u201d (KNM\u2013WT 17000) (discovery 1985).<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table16-R\" style=\"height: 0\">\n<td class=\"Table16-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Brain Size<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table16-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 1.5pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">410 cc<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table16-R\" style=\"height: 0\">\n<td class=\"Table16-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Dentition<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table16-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 1.5pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><em>P. aethiopicus<\/em> has the shared derived traits of large flat premolars and molars, although few teeth have been found.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table16-R\" style=\"height: 0\">\n<td class=\"Table16-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Cranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table16-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 1.5pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Large flaring zygomatic arches for accommodating large chewing muscles (the temporalis muscle), a sagittal crest for increased muscle attachment of the chewing muscles to the skull, and a robust mandible and supraorbital torus (brow ridge).<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table16-R\" style=\"height: 0\">\n<td class=\"Table16-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Postcranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table16-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">A proximal tibia indicates bipedality and similar size to <em>Au. afarensis<\/em>.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table16-R\" style=\"height: 0\">\n<td class=\"Table16-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Culture<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table16-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">N\/A<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table16-R\" style=\"height: 0\">\n<td class=\"Table16-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Other<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table16-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 1.5pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">The \u201cBlack Skull\u201d is so called because of the mineral manganese that stained it black during fossilization.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div style=\"text-align: left\">\n<table style=\"width: 450pt\">\n<tbody>\n<tr class=\"Table17-R\" style=\"height: 0\">\n<td class=\"Table17-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Hominin<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table17-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><em>Paranthropus boisei<\/em><\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table17-R\" style=\"height: 0\">\n<td class=\"Table17-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Dates<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table17-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">2.4 mya to 1.4 mya<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table17-R\" style=\"height: 0\">\n<td class=\"Table17-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Region(s)<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table17-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Koobi Fora, West Turkana, and Chesowanja (Kenya); Malema-Chiwondo (Malawi), Olduvai Gorge and Peninj (Tanzania); and Omo River basin and Konso (Ethiopia)<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table17-R\" style=\"height: 0\">\n<td class=\"Table17-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Famous discoveries<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table17-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">\u201cZinj,\u201d or sometimes \u201cNutcracker Man\u201d (OH5), in 1959 by Mary Leakey. The Peninj mandible from Tanzania, found in 1964 by Kimoya Kimeu.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table17-R\" style=\"height: 0\">\n<td class=\"Table17-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Brain <\/strong><strong>s<\/strong><strong>ize<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table17-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">500 cc to 550 cc<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table17-R\" style=\"height: 0\">\n<td class=\"Table17-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Dentition<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table17-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Very large, flat posterior dentition (largest of all hominins currently known). Much smaller anterior dentition. Very thick dental enamel.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table17-R\" style=\"height: 0\">\n<td class=\"Table17-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Cranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table17-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Indications of very large chewing muscles (e.g., flaring zygomatic arches and a large sagittal crest).<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table17-R\" style=\"height: 0\">\n<td class=\"Table17-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Postcranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table17-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Evidence for high variability and sexual dimorphism, with estimates of males at 1.37 metres tall and females at 1.24 metres.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table17-R\" style=\"height: 0\">\n<td class=\"Table17-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Culture<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table17-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Richard Leakey and Bernard Wood have both suggested that<em> P. boisei<\/em> could have made and used stone tools. Tools dated to 2.5 mya in Ethiopia have been argued to possibly belong to this species.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table17-R\" style=\"height: 0\">\n<td class=\"Table17-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Other<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table17-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Despite the cranial features of <em>P. boisei<\/em> indicating a tough diet of tubers, nuts, and seeds, isotopes indicate a diet high in C4 foods (e.g., grasses, such as sedges). This differs from what is seen in<em> P. robustus<\/em>.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div style=\"text-align: left\">\n<table style=\"width: 450pt\">\n<tbody>\n<tr class=\"Table18-R\" style=\"height: 0\">\n<td class=\"Table18-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Hominin<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table18-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\"><em>Australopithecus sediba<\/em><\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table18-R\" style=\"height: 0\">\n<td class=\"Table18-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Dates<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table18-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">1.97 mya<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table18-R\" style=\"height: 0\">\n<td class=\"Table18-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Region(s)<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table18-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">Malapa Fossil Site (South Africa)<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table18-R\" style=\"height: 0\">\n<td class=\"Table18-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Famous discoveries<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table18-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">Karabo (MH1) (discovery in 2008)<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table18-R\" style=\"height: 0\">\n<td class=\"Table18-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Brain size<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table18-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">420 cc to 450 cc<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table18-R\" style=\"height: 0\">\n<td class=\"Table18-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Dentition<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table18-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">Small dentition with Australopithecine cusp-spacing.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table18-R\" style=\"height: 0\">\n<td class=\"Table18-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Cranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table18-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">Small brain size (<em>Australopithecus<\/em>-like) but gracile mandible (<em>Homo<\/em>-like).<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table18-R\" style=\"height: 0\">\n<td class=\"Table18-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Postcranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table18-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">Scientists have interpreted this mixture of traits (such as a robust ankle but evidence for an arch in the foot) as a transitional phase between a body previously adapted to arborealism (tree climbing, particularly in evidence from the bones of the wrist) to one that adapted to bipedal ground walking.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table18-R\" style=\"height: 0\">\n<td class=\"Table18-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Culture<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table18-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">None of direct association, but some have argued that a modern hand morphology (shorter fingers and a longer thumb) means that adaptations to tool manufacture and use may be present in this species.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table18-R\" style=\"height: 0\">\n<td class=\"Table18-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Other<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table18-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">It was first discovered through a clavicle bone in 2008 by nine-year-old Matthew Berger, son of paleoanthropologist Lee Berger.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div style=\"text-align: left\">\n<table style=\"width: 450pt\">\n<tbody>\n<tr class=\"Table19-R\" style=\"height: 0\">\n<td class=\"Table19-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Hominin<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table19-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><em>Paranthropus robustus<\/em><\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table19-R\" style=\"height: 0\">\n<td class=\"Table19-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Dates<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table19-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">2.3 mya to 1 mya<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table19-R\" style=\"height: 0\">\n<td class=\"Table19-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Region(s)<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table19-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Kromdraai B, Swartkrans, Gondolin, Drimolen, and Coopers Cave (South Africa)<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table19-R\" style=\"height: 0\">\n<td class=\"Table19-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Famous discoveries<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table19-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">SK48 (original skull)<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table19-R\" style=\"height: 0\">\n<td class=\"Table19-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Brain <\/strong><strong>s<\/strong><strong>ize<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table19-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">410 cc to 530 cc<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table19-R\" style=\"height: 0\">\n<td class=\"Table19-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Dentition<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table19-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Large posterior teeth with thick enamel, consistent with other Robust Australopithecines. Enamel hypoplasia is also common in this species, possibly because of instability in the development of large, thick enameled dentition.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table19-R\" style=\"height: 0\">\n<td class=\"Table19-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Cranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table19-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><em>P. robustus<\/em> features are neither as \u201chyper-robust\u201d as <em>P. boisei<\/em> or as ancestral in features as <em>P. aethiopicus<\/em>. They have been described as less derived, more general features that are shared with both East African species (e.g., the sagittal crest and zygomatic flaring).<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table19-R\" style=\"height: 0\">\n<td class=\"Table19-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Postcranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table19-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Reconstructions indicate sexual dimorphism.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table19-R\" style=\"height: 0\">\n<td class=\"Table19-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Culture<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table19-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">N\/A<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table19-R\" style=\"height: 0\">\n<td class=\"Table19-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: transparent;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><strong>Other<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table19-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Several of these fossils are fragmentary in nature, distorted, and not well preserved, because they have been recovered from quarry breccia using explosives.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div class=\"textbox shaded\">\n<h2>Summary<\/h2>\n<p class=\"import-Normal\"><span style=\"color: #000000\">The fossil record of our earliest hominin relatives has allowed paleoanthropologists to unpack some of the mysteries of our evolution. We now know that traits associated with bipedalism evolved before other \u201chuman-like\u201d traits, even though the first hominins were still very capable of arboreal locomotion. We also know that, for much of this time, hominin taxa were diverse in the way they looked and what they ate, and they were widely distributed across the African continent. And we know that the environments in which these hominins lived underwent many changes over this time during several warming and cooling phases.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Yet this knowledge has opened up many new mysteries. We still need to better differentiate some taxa. In addition, there are ongoing debates about why certain traits evolved and what they meant for the extinction of some of our relatives (like the robust australopiths). The capabilities of these early hominins with respect to tool use and manufacture is also still uncertain.<\/span><\/p>\n<h2 class=\"import-Normal\"><strong><span style=\"color: #000000\">Review Questions<br \/>\n<\/span><\/strong><\/h2>\n<ul>\n<li class=\"import-Normal\"><span style=\"color: #000000\">What is the difference between a \u201cderived\u201d versus an \u201cancestral\u201d trait? Give an example of both, seen in <em>Au. afarensis<\/em>.<\/span><\/li>\n<li class=\"import-Normal\"><span style=\"color: #000000\">Which of the paleoenvironment hypotheses have been used to describe early hominin diversity, and which have been used to describe bipedalism?<\/span><\/li>\n<li class=\"import-Normal\"><span style=\"color: #000000\">Which anatomical features for bipedalism do we see in early hominins?<\/span><\/li>\n<li class=\"import-Normal\"><span style=\"color: #000000\">Describe the dentition of gracile and robust australopithecines. What might these tell us about their diets?<\/span><\/li>\n<li class=\"import-Normal\"><span style=\"color: #000000\">List the hominin species argued to be associated with stone tool technologies. Are you convinced of these associations? Why\/why not?<\/span><\/li>\n<\/ul>\n<\/div>\n<h2><span style=\"color: #000000\">Key Terms<\/span><\/h2>\n<p><span style=\"color: #000000\"><strong>Arboreal:<\/strong> Related to trees or woodland.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Aridification:<\/strong> Becoming increasingly arid or dry, as related to the climate or environment.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Aridity Hypothesis:<\/strong> The hypothesis that long-term aridification and expansion of savannah biomes were drivers in diversification in early hominin evolution.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Assemblage:<\/strong> A collection demonstrating a pattern. Often pertaining to a site or region.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Bipedalism:<\/strong> The locomotor ability to walk on two legs.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Breccia:<\/strong> Hard, calcareous sedimentary rock.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Canines:<\/strong> The pointy teeth just next to the incisors, in the front of the mouth.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Cheek teeth:<\/strong> Or hind dentition (molars and premolars).<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Chronospecies:<\/strong> Species that are said to evolve into another species, in a linear fashion, over time.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Clade:<\/strong> A group of species or taxa with a shared common ancestor.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Cladistics:<\/strong> The field of grouping organisms into those with shared ancestry.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Context:<\/strong> As pertaining to palaeoanthropology, this term refers to the place where an artifact or fossil is found.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Cores:<\/strong> The remains of a rock that has been flaked or knapped.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Cusps:<\/strong> The ridges or \u201cbumps\u201d on the teeth.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Dental formula:<\/strong> A technique to describe the number of incisors, canines, premolars, and molars in each quadrant of the mouth.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Derived traits:<\/strong> Newly evolved traits that differ from those seen in the ancestor.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Diastema:<\/strong> A tooth gap between the incisors and canines.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Early Stone Age (ESA):<\/strong> The earliest-described archaeological period in which we start seeing stone-tool technology.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>East African Rift System (EARS):<\/strong> This term is often used to refer to the Rift Valley, expanding from Malawi to Ethiopia. This active geological structure is responsible for much of the visibility of the paleoanthropological record in East Africa.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Enamel:<\/strong> The highly mineralized outer layer of the tooth.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Encephalization:<\/strong> Expansion of the brain.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Extant:<\/strong> Currently living\u2014i.e., not extinct.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Fallback foods:<\/strong> Foods that may not be preferred by an animal (e.g., foods that are not nutritionally dense) but that are essential for survival in times of stress or scarcity.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Fauna:<\/strong> The animals of a particular region, habitat, or geological period.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Faunal assemblages:<\/strong> Collections of fossils of the animals found at a site.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Faunal turnover:<\/strong> The rate at which species go extinct and are replaced with new species.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Flake:<\/strong> The piece knocked off of a stone core during the manufacture of a tool, which may be used as a stone tool.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Flora:<\/strong> The plants of a particular region, habitat, or geological period.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Folivorous:<\/strong> Foliage-eating.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Foramen magnum:<\/strong> The large hole (foramen) at the base of the cranium, through which the spinal cord enters the skull.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Fossil:<\/strong> The remains or impression of an organism from the past.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Frugivorous:<\/strong> Fruit-eating.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Generalist:<\/strong> A species that can thrive in a wide variety of habitats and can have a varied diet.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Glacial:<\/strong> Colder, drier periods during an ice age when there is more ice trapped at the poles.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Gracile:<\/strong> Slender, less rugged, or pronounced features.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Hallux:<\/strong> The big toe.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Holotype:<\/strong> A single specimen from which a species or taxon is described or named.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Hominin:<\/strong> A primate category that includes humans and our fossil relatives since our divergence from extant great apes.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Honing P3:<\/strong> The mandibular premolar alongside the canine (in primates, the P3), which is angled to give space for (and sharpen) the upper canines.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Hyper-robust:<\/strong> Even more robust than considered normal in the Paranthropus genus.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Hypodigm:<\/strong> A sample (here, fossil) from which researchers extrapolate features of a population.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Incisiform:<\/strong> An adjective referring to a canine that appears more incisor-like in morphology.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Incisors:<\/strong> The teeth in the front of the mouth, used to bite off food.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Interglacial:<\/strong> A period of milder climate in between two glacial periods.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Isotopes:<\/strong> Two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons, giving them the same chemical properties but different atomic masses.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Knappers:<\/strong> The people who fractured rocks in order to manufacture tools.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Knapping:<\/strong> The fracturing of rocks for the manufacture of tools.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Large Cutting Tool (LCT):<\/strong> A tool that is shaped to have functional edges.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Last Common Ancestor (LCA):<\/strong> The hypothetical final ancestor (or ancestral population) of two or more taxa before their divergence.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Lithic:<\/strong> Relating to stone (here to stone tools).<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Lumbar lordosis:<\/strong> The inward curving of the lower (lumbar) parts of the spine. The lower curve in the human S-shaped spine.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Lumpers:<\/strong> Researchers who prefer to lump variable specimens into a single species or taxon and who feel high levels of variation is biologically real.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Megadont:<\/strong> An organism with extremely large dentition compared with body size.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Metacarpals:<\/strong> The long bones of the hand that connect to the phalanges (finger bones).<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Molars:<\/strong> The largest, most posterior of the hind dentition.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Monophyletic:<\/strong> A taxon or group of taxa descended from a common ancestor that is not shared with another taxon or group.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Morphology:<\/strong> The study of the form or size and shape of things; in this case, skeletal parts.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Mosaic evolution:<\/strong> The concept that evolutionary change does not occur homogeneously throughout the body in organisms.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Obligate bipedalism:<\/strong> Where the primary form of locomotion for an organism is bipedal.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Occlude:<\/strong> When the teeth from the maxilla come into contact with the teeth in the mandible.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Oldowan:<\/strong> Lower Paleolithic, the earliest stone tool culture.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Orthognathic:<\/strong> The face below the eyes is relatively flat and does not jut out anteriorly.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Paleoanthropologists:<\/strong> Researchers that study human evolution.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Paleoenvironment:<\/strong> An environment from a period in the Earth\u2019s geological past.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Parabolic:<\/strong> Like a parabola (parabola-shaped).<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Phalanges:<\/strong> Long bones in the hand and fingers.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Phylogenetics:<\/strong> The study of phylogeny.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Phylogeny:<\/strong> The study of the evolutionary relationships between groups of organisms.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Pliocene:<\/strong> A geological epoch between the Miocene and Pleistocene.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Polytypic:<\/strong> In reference to taxonomy, having two or more group variants capable of interacting and breeding biologically but having morphological population differences.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Postcranium:<\/strong> The skeleton below the cranium (head).<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Premolars:<\/strong> The smallest of the hind teeth, behind the canines.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Procumbent:<\/strong> In reference to incisors, tilting forward.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Prognathic:<\/strong> In reference to the face, the area below the eyes juts anteriorly.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Quaternary Ice Age:<\/strong> The most recent geological time period, which includes the Pleistocene and Holocene Epochs and which is defined by the cyclicity of increasing and decreasing ice sheets at the poles.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Relative dating:<\/strong> Dating techniques that refer to a temporal sequence (i.e., older or younger than others in the reference) and do not estimate actual or absolute dates.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Robust:<\/strong> Rugged or exaggerated features.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Site:<\/strong> A place in which evidence of past societies\/species\/activities may be observed through archaeological or paleontological practice.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Specialist:<\/strong> A specialist species can thrive only in a narrow range of environmental conditions or has a limited diet.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Splitters:<\/strong> Researchers who prefer to split a highly variable taxon into multiple groups or species.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Taxa:<\/strong> Plural of taxon, a taxonomic group such as species, genus, or family.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Taxonomy:<\/strong> The science of grouping and classifying organisms.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Techno-complex:<\/strong> A term encompassing multiple assemblages that share similar traits in terms of artifact production and morphology.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Thermoregulation:<\/strong> Maintaining body temperature through physiologically cooling or warming the body.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Ungulates:<\/strong> Hoofed mammals\u2014e.g., cows and kudu.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Volcanic tufts:<\/strong> Rock made from ash from volcanic eruptions in the past.<\/span><\/p>\n<p><span style=\"color: #000000\"><strong>Valgus knee:<\/strong> The angle of the knee between the femur and tibia, which allows for weight distribution to be angled closer to the point above the centre of gravity (i.e., between the feet) in bipeds.<\/span><\/p>\n<h2 class=\"import-Normal\"><strong><span style=\"color: #000000\">For Further Exploration<br \/>\n<\/span><\/strong><\/h2>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><a href=\"https:\/\/humanorigins.si.edu\/evidence\" target=\"_blank\">The Smithsonian Institution website<\/a> hosts descriptions of fossil species, an interactive timeline, and much more.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><a href=\"https:\/\/www.maropeng.co.za\/content\/page\/human-evolution\" target=\"_blank\">The Maropeng Museum website<\/a> hosts a wealth of information regarding South African Fossil Bearing sites in the Cradle of Humankind<strong>.<\/strong><\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><a href=\"https:\/\/perot-museum.imgix.net\/2019-08-naledi-sediba-quick-comparison.pdf\" target=\"_blank\">This quick comparison between <em>Homo naledi<\/em> and <em>Australopithecus sediba<\/em><\/a> from the Perot Museum.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><a href=\"https:\/\/www.dropbox.com\/s\/l1d2hv42psj21y9\/Braided%20Stream-1920.mp4?dl=0\" target=\"_blank\">This explanation of the braided stream<\/a> by the Perot Museum.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><a href=\"https:\/\/www.hetmp.com\/\" target=\"_blank\">A collation of 3-D files for visualizing<\/a> (or even 3-D printing) for homes, schools, and universities.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><a href=\"https:\/\/www.pbslearningmedia.org\/resource\/tdc02.sci.life.evo.lp_humanevo\/human-evolution.\" target=\"_blank\">PBS learning materials<\/a>, including videos and diagrams of the Laetoli footprints, bipedalism, and fossils.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">A wealth of <a href=\"https:\/\/australianmuseum.net.au\/learn\/science\/human-evolution\/\" target=\"_blank\">information from the Australian Museum website<\/a>, including species descriptions, family trees, and explanations of bipedalism and diet<strong>.<\/strong><\/span><\/p>\n<h2 class=\"import-Normal\"><span style=\"color: #000000\"><strong>References<\/strong><\/span><\/h2>\n<p>Aiello, L. C.; Wheeler, P. (1995).The Expensive-Tissue Hypothesis: The Brain and the Digestive System in Human and Primate Evolution. <em>Current Anthropology<\/em>, 36 (2):199-221<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Alemseged, Zeresenay, Fred Spoor, William H. Kimbel, Ren\u00e9 Bobe, Denis Geraads, Denn\u00e9 Reed, and Jonathan G. 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The Evolution of Modern Human Childbirth. <em>Yearbook of Physical Anthropology<\/em>. 3589-124<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Semaw, Sileshi. 2000. \u201cThe World\u2019s Oldest Stone Artefacts from Gona, Ethiopia: Their Implications for Understanding Stone Technology and Patterns of Human Evolution between 2.6 Million Years Ago and 1.5 Million Years Ago.\u201d <em>Journal of Archaeological Science<\/em> 27(12): 1197\u20131214.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Spoor, Fred. 2015. \u201cPalaeoanthropology: The Middle Pliocene Gets Crowded.\u201d<em> Nature<\/em> 521 (7553): 432\u2013433.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Strait, David S., Frederick E. 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Labuschagne. 2002. \u201c\u2018Mrs. Ples\u2019 (Sts 5) from Sterkfontein: An Adolescent Male?\u201d <em>South African Journal of Science<\/em> 98 (1\u20132): 21\u201322.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Toth, Nicholas. 1985. \u201cThe Oldowan Reassessed.\u201d <em>Journal of Archaeological Science<\/em> 12 (2): 101\u2013120.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Van Le, Q., Isbell, L. A., Matsumoto, J., Nguyen, M., Hori, E., Maior, R. S., Tomaz, C., Tran, A. H., Ono, T., &amp; Nishijo, H. (2013). 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Leakey. 1988. \u201cThe Evolution of <em>Australopithecus boisei<\/em>.\u201d In <em>Evolutionary History of the \u201cRobust\u201d Australopithecines<\/em>, edited by F. E. Grine, 247\u2013258. New York: Aldine de Gruyter.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Walker, Alan, Richard E. Leakey, John M. Harris, and Francis H. Brown. 1986. \u201c2.5-my <em>Australopithecus boisei<\/em> from West of Lake Turkana, Kenya.\u201d <em>Nature<\/em> 322 (6079): 517\u2013522.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Ward, Carol, Meave Leakey, and Alan Walker. 1999. \u201cThe New Hominid Species <em>Australopithecus anamensis<\/em>.\u201d <em>Evolutionary Anthropology<\/em> 7 (6): 197\u2013205.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">White, Tim D. 1988. \u201cThe Comparative Biology of \u2018Robust\u2019 Australopithecus: Clues from Content.\u201d In <em>Evolutionary History of the \u201cRobust\u201d Australopithecines<\/em>, edited by F. E. Grine, 449\u2013483. New York: Aldine de Gruyter.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">White, Tim D., Gen Suwa, and Berhane Asfaw. 1994. \u201c<em>Australopithecus ramidus<\/em>, a New Species of Early Hominid from Aramis, Ethiopia.\u201d <em>Nature<\/em> 371 (6495): 306\u2013312.<\/span><\/p>\n<p>Wrangham, R.W. et al. (1999). \"The Raw and the Stolen\".\u00a0<em>Current Anthropology<\/em>.\u00a040\u00a0(5):\u00a0567\u2013594.\u00a0<a href=\"https:\/\/en.wikipedia.org\/wiki\/Doi_(identifier)\" target=\"_blank\">doi<\/a>:<a href=\"https:\/\/doi.org\/10.1086%2F300083\" target=\"_blank\">10.1086\/300083<\/a>.<\/p>\n<p>Wrangham, Richard. (2009). <em>Catching Fire: How Cooking Made Us Human.<\/em>\u00a0New York, NY: Basic Books.<\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Wood, Bernard. 2010. \u201cReconstructing Human Evolution: Achievements, Challenges, and Opportunities.\u201d <em>Proceedings of the National Academy of Sciences<\/em> 10 (2): 8902\u20138909.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Wood, Bernard, and Eve K. Boyle. 2016. \u201cHominin Taxic Diversity: Fact or Fantasy?\u201d <em>Yearbook of Physical Anthropology<\/em> 159 (S61): 37\u201378.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Wood, Bernard, and Kes Schroer. 2017. \u201cParanthropus: Where Do Things Stand?\u201d In <em>Human Paleontology and Prehistory<\/em>, edited by A. Marom and E. Hovers, 95\u2013107. New York: Springer, Cham.<\/span><\/p>\n<h2 class=\"import-Normal\"><span style=\"color: #000000\">Acknowledgements<\/span><\/h2>\n<p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">All of the authors in this section are students and early career researchers in paleoanthropology and related fields in South Africa (or at least have worked in South Africa). We wish to thank everyone who supports young and diverse talent in this field and would love to further acknowledge Black, African, and female academics who have helped pave the way for us.<\/span><\/p>\n<\/div>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1695_1872\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1695_1872\"><div tabindex=\"-1\"><div class=\"__UNKNOWN__\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Bonnie Yoshida-Levine Ph.D., Grossmont College<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\"><em>This chapter is a revision from <\/em><em>\"<\/em><a class=\"rId7\" style=\"color: #000000\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-15\/\"><em>Chapter 10: Early Members of the Genus Homo<\/em><\/a><em>\" by Bonnie Yoshida-Levine. In <\/em><a class=\"rId8\" style=\"color: #000000\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\"><em>Explorations: An Open Invitation to Biological Anthropology, first edition<\/em><\/a><em>, edited by Beth Shook, Katie Nelson, Kelsie Aguilera, and Lara Braff, which is licensed under <\/em><a class=\"rId9\" style=\"color: #000000\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\"><em>CC BY-NC 4.0<\/em><\/a><em>.<\/em><\/span><\/p>\n<div class=\"textbox textbox--learning-objectives\">\n<header class=\"textbox__header\">\n<h2 class=\"textbox__title\">Learning Objectives<\/h2>\n<\/header>\n<div class=\"textbox__content\">\n<ul>\n<li>Describe how early Pleistocene climate change influenced the evolution of the genus Homo.<\/li>\n<li>Identify the characteristics that define the genus Homo.<\/li>\n<li>Describe the skeletal anatomy of Homo habilis\u00a0and Homo erectus based on the fossil evidence.<\/li>\n<li>Assess opposing points of view about how early Homo should be classified.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<p><span style=\"color: #000000\">The boy was no older than nine years when he perished by the swampy shores of the lake. After death, his slender, long-limbed body sank into the mud of the lake shallows. His bones fossilized and lay undisturbed for 1.5 million years. In the 1980s, fossil hunter Kamoya Kimeu, working on the western shore of Lake Turkana, Kenya, glimpsed a dark-coloured piece of bone eroding in a hillside. This small skull fragment led to the discovery of what is arguably the world\u2019s most complete early hominin fossil\u2014a youth identified as a member of the species <em>Homo erectus<\/em>. Now known as Nariokotome Boy, after the nearby lake village, the skeleton has provided a wealth of information about the early evolution of our own genus, <em>Homo <\/em>(see Figure 11.1). Today, a stone monument with an inscription in three languages\u2014English, Swahili, and the local Turkana language\u2014marks the site of this momentous fossil discovery.<\/span><\/p>\n<p><img class=\"aligncenter\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2023\/06\/image8-1.jpg\" alt=\"Front view of near-complete skeleton\" width=\"407\" height=\"407\" \/><\/p>\n<figure style=\"width: 405px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image13-1.jpg\" alt=\"Reconstructed head and shoulders of a young Homo erectus.\" width=\"405\" height=\"308\" \/><figcaption class=\"wp-caption-text\">Figure 11.1a-b: a. Skeleton of a young male Homo erectus known as \u201cNariokotome Boy\u201d; b. an artist\u2019s depiction of how he may have looked during his life. This is the most complete hominin fossil from this time period ever found. Credit: a.<a href=\"https:\/\/humanorigins.si.edu\/evidence\/human-fossils\/fossils\/knm-wt-15000\" target=\"_blank\"> KNM-WT 15000 Turkana Boy Skeleton<\/a> by<a href=\"https:\/\/www.si.edu\/\" target=\"_blank\"> Smithsonian<\/a> [exhibit:<a href=\"https:\/\/humanorigins.si.edu\/research\" target=\"_blank\"> Human Evolution<\/a> Evidence, Human Fossils, Fossils, KNM-WT 15000] is<a href=\"https:\/\/www.si.edu\/termsofuse\/\" target=\"_blank\"> copyrighted and used for educational and non-commercial purposes as outlined by the Smithsonian<\/a>. b. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Homo-erectus_Turkana-Boy_%28Ausschnitt%29_Fundort_Nariokotome,_Kenia,_Rekonstruktion_im_Neanderthal_Museum.jpg\" target=\"_blank\">Homo-erectus Turkana-Boy (Ausschnitt) Fundort Nariokotome, Kenia, Rekonstruktion im Neanderthal Museum<\/a> by Neanderthal Museum is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/deed.en\" target=\"_blank\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Chapter 10 described our oldest human ancestors, primarily members of the genus <em>Australopithecus<\/em>, who lived between 2 million and 4 million years ago. This chapter introduces the earliest members of the genus <em>Homo<\/em>, focusing on <em>Homo habilis<\/em> and <em>Homo erectus<\/em>.<\/span><\/p>\n<h2 class=\"import-Normal\"><span style=\"color: #000000\">Defining the Genus <em>Homo<\/em><\/span><\/h2>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Because Anthropology is fundamentally concerned with what makes us human, defining our own genus takes on special significance for anthropologists. Ever since scientists acknowledged the existence of extinct species of humans, they have debated which of them display sufficient \u201chumanness\u201d to merit classification in the genus <em>Homo<\/em>. When grouping species into a common genus, biologists consider criteria such as physical characteristics (morphology), evidence of recent common ancestry, and adaptive strategy (use of the environment). However, there is disagreement about which of those criteria should be prioritized, as well as how specific fossils should be interpreted in light of the criteria.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Nevertheless, there is general agreement that species classified as <em>Homo<\/em> should share characteristics that are broadly similar within our species. These include the following:<\/span><\/p>\n<ul>\n<li class=\"import-Normal\" style=\"background-color: transparent;text-align: left;text-indent: 18pt\"><span style=\"color: #000000\">a relatively large brain size<\/span><\/li>\n<li class=\"import-Normal\" style=\"background-color: transparent;text-align: left;text-indent: 18pt\"><span style=\"color: #000000\">a smaller and flatter face<\/span><\/li>\n<li class=\"import-Normal\" style=\"background-color: transparent;text-align: left;text-indent: 18pt\"><span style=\"color: #000000\">smaller jaws and teeth<\/span><\/li>\n<li class=\"import-Normal\" style=\"background-color: transparent;text-align: left;text-indent: 18pt\"><span style=\"color: #000000\">increased reliance on culture, particularly the use of stone tools, to exploit a greater diversity of environments (adaptive zone).<\/span><\/li>\n<\/ul>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Some researchers would include larger overall body size and limb proportions (longer legs\/shorter arms) in this list. While these criteria seem relatively clear-cut, evaluating them in the fossil record has proved more difficult, particularly for the earliest members of the genus. There are several reasons for this. First, many fossil specimens dating to this time period are incomplete and poorly preserved. Second, early <em>Homo<\/em> fossils appear quite variable in brain size, facial features, and teeth and body size, and there is not yet consensus about how to best make sense of this diversity. Finally, there is growing evidence that the evolution of the genus <em>Homo<\/em> proceeded in a mosaic pattern: in other words, these characteristics did not appear all at once in a single species; rather, they were patchily distributed in different species from different regions and time periods. Consequently, different researchers have come up with conflicting classification schemes depending on which criteria they think are most important.<\/span><\/p>\n<h2 class=\"import-Normal\"><span style=\"color: #000000\">Climate Change and Human Evolution<\/span><\/h2>\n<p class=\"import-Normal\"><span style=\"color: #000000\">A key goal in the study of human origins is to learn about the environmental pressures that may have shaped human evolution. As indicated in Chapter 8, scientists use a variety of techniques to reconstruct ancient environments. These include stable isotopes, core samples from oceans and lakes, windblown dust, analysis of geological formations and volcanoes, and fossils of ancient plant and animal communities. Such studies have provided valuable information about the environmental context of early <em>Homo<\/em>.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">The early hominin species covered in Chapter 10, such as <em>Ardipithecus ramidus<\/em> and <em>Australopithecus afarensis<\/em>, evolved during the late <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1404\">Pliocene<\/a><\/strong> epoch. The Pliocene (5.3 million to 2.6 million years ago) was marked by cooler and drier conditions, with ice caps forming permanently at the poles. Still, Earth\u2019s climate during the Pliocene was considerably warmer and wetter than at present.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">The subsequent <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1549\">Pleistocene<\/a> <\/strong>epoch (2.6 million years to 11,000 years ago) ushered in major environmental change. The Pleistocene is popularly referred to as the Ice Age. Since the term \u201cIce Age\u201d tends to conjure up images of glaciers and woolly mammoths, one would naturally assume that this was a period of uniformly cold climate around the globe. But this is not actually the case. Instead, climate became much more variable, cycling abruptly between warm\/wet (interglacial) and cold\/dry (glacial) cycles. These patterns were influenced by changes in Earth\u2019s elliptical orbit around the sun. As is shown in Figure 11.2, each cycle averaged about 41,000 years during the early Pleistocene; the cycles then lengthened to about 100,000 years starting around 1.25 million years ago. Since mountain ranges, wind patterns, ocean currents, and volcanic activity can all influence climate patterns, there were wide-ranging regional and local effects.<\/span><\/p>\n<figure style=\"width: 655px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image7-3.png\" alt=\"Graph depicts five million years of climate change from sediment cores.\" width=\"655\" height=\"197\" \/><figcaption class=\"wp-caption-text\">Figure 11.2: Temperature estimates during the last five million years, extrapolated from deep-sea core data. Lower temperatures and increased temperature oscillations start at 2.6 million years ago. Glacial\/interglacial cycles during the early part of the epoch are shorter, each averaging about 41,000 years. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Five_Myr_Climate_Change.png\" target=\"_blank\">Five Myr Climate Change<\/a> by<a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Dragons_flight\" target=\"_blank\"> Dragons flight<\/a> (Robert A. Rohde), based on data from Lisiechi and Raymo (2005), is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\"> CC BY-SA 3.0 License.<\/a><\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Data on ancient geography and climate help us understand how our ancestors moved and migrated to different parts of the world\u2014as well as the constraints under which they operated. When periods of global cooling dominated, sea levels were lower as more water was captured as glacial ice. This exposed continental margins and opened pathways between land masses. During glacial periods, the large Indonesian islands of Sumatra, Java, and Borneo were connected to the Southeast Asian mainland, while New Guinea was part of the southern landmass of greater Australia. There was a land bridge connection between Britain and continental Europe, and an icy, treeless plain known as Beringia connected Northern Asia and Alaska. At the same time, glaciation made some northern areas inaccessible to human habitation. For example, there is evidence that hominin species were in Britain 950,000 years ago, but it does not appear that Britain was continuously occupied during this period. It is speculated that these early humans may have died out or been forced to abandon the region during glacial periods.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">In Africa, paleoclimate research has determined that grasslands (shown in Figure 11.3) expanded and shrank multiple times during this period, even as they expanded over the long term (deMenocal 2014). From studies of fossils, paleontologists have been able to reconstruct Pleistocene animal communities and to consider how they were affected by the changing climate. Among the African animal populations, the number of grazing animal species such as antelope increased. Although the African and Eurasian continents are connected by land, the Sahara desert and the mountainous topography of North Africa serve as natural barriers to crossing. But the fossil record shows that at different times animal species have moved back and forth between Africa and Eurasia. During the early Pleistocene, there is evidence of African mammal species such as baboons, hippos, antelope, and African buffalo migrating out of Africa into Eurasia during periods of aridity (Belmaker 2010).<\/span><\/p>\n<figure style=\"width: 583px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image3-2.jpg\" alt=\"Dry grassy field with a few trees and mountains in the far distance.\" width=\"583\" height=\"406\" \/><figcaption class=\"wp-caption-text\">Figure 11.3: A savanna grassland in East Africa. Habitats such as this were becoming increasingly common during the Pleistocene. Credit: <a href=\"https:\/\/www.flickr.com\/photos\/ilri\/5130992564\" target=\"_blank\">Savanna grasslands of East Africa<\/a> by<a href=\"https:\/\/www.flickr.com\/photos\/ilri\/\" target=\"_blank\"> International Livestock Research Institute (ILRI)\/Elsworth<\/a> is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\" target=\"_blank\"> CC BY-NC-SA 2.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">This changing environment was undoubtedly challenging for our ancestors, but it offered new opportunities to make a living. It is theorized that one solution adopted by some hominins was to specialize in feeding on the new types of plants growing in this landscape. The robust australopithecines (described in Chapter 10) likely developed their large molar teeth with thick enamel in order to exploit this particular dietary niche.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Members of the genus <em>Homo <\/em>took a different route. Faced with the unstable African climate and shifting landscape, it is proposed that they evolved bigger brains that might have enabled them to rely on cultural solutions such as crafting stone tools that opened up new foraging opportunities. This strategy of behavioural flexibility might have served them well during this unpredictable time and may have led to new innovations such as increased meat-eating, cooperative hunting, and the exploitation of new environments outside Africa. <\/span><\/p>\n<h2 class=\"import-Normal\"><span style=\"color: #000000\"><em>Homo habilis<\/em>: The Earliest Members of Our Genus<\/span><\/h2>\n<p class=\"import-Normal\"><span style=\"color: #000000\"><em>Homo habilis<\/em> has traditionally been considered the earliest species placed in the genus <em>Homo<\/em>. However, as we will see, there is substantial disagreement among paleoanthropologists about the fossils classified as <em>Homo habilis<\/em>, including whether they come from a single species or multiple, or even whether they should be part of the genus <em>Homo <\/em>at all.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\"><em>Homo habilis<\/em> has a somewhat larger brain size\u2014an average of 650 cubic centimetres (cc)\u2014compared to <em>Australopithecus<\/em> with less than 500 cc. Additionally, the skull is more rounded and the face less prognathic. However, the postcranial remains show a body size and proportions similar to <em>Australopithecus<\/em>.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Known dates for fossils identified as <em>Homo habilis<\/em> range from about 2.5 million years ago to 1.7 million years ago. Recently, a partial lower jaw dated to 2.8 million years from the site of Ledi-Gararu in Ethiopia has been tentatively identified as belonging to the genus <em>Homo<\/em> (Villmoare et al. 2015). If this classification holds up, it would push the origins of our genus back even further.<\/span><\/p>\n<figure style=\"width: 554px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image16.jpg\" alt=\"Africa map with South Africa, Tanzania, Kenya, and Ethiopia shaded.\" width=\"554\" height=\"717\" \/><figcaption class=\"wp-caption-text\">Figure 11.4: Map showing major sites where <em>Homo habilis<\/em> fossils have been found. Ledi-Geraru is located in Ethiopia, Koobi Fora and Lake Turkana Basin are located in Kenya, the Olduvai Gorge is located in Tanzania, and Tuang, Malapa, Rising Star and Sterkfontein are located in South Africa. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-15\/\" target=\"_blank\">Homo habilis site map (Figure 10.4)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Chelsea Barron at<a href=\"https:\/\/www.csuchico.edu\/geop\/geoplace\/index.shtml\" target=\"_blank\"> GeoPlace, California State University, Chico<\/a> is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\"> CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\"><span style=\"color: #000000\">The first fossils to be named <em>Homo habilis<\/em> were discovered at the site of Olduvai Gorge in Tanzania, East Africa, by members of a team led by Louis and Mary Leakey (Figure 11.4). The Leakey family had been conducting fieldwork in the area since the 1930s and had discovered other hominin fossils at the site, such as the robust <em>Paranthropos boisei<\/em>. The key specimen, a juvenile individual, was actually found by their 20-year-old son Jonathan Leakey. Louis Leakey invited South African paleoanthropologist Philip Tobias and British anatomist John Napier to reconstruct and analyse the remains. The fossil of the juvenile shown in Figure 11.5 (now known as OH-7) consisted of a lower jaw, parts of the parietal bones of the skull, and some hand and finger bones. The fossil was dated by potassium-argon dating to about 1.75 million years. In 1964, the team published their findings in the scientific journal <em>Nature <\/em>(Leakey et al. 1964)<em>. <\/em>As described in the publication, the new fossils had smaller molar teeth that were less \u201cbulgy\u201d than australopithecine teeth. Although the primary specimen was not yet fully grown, an estimate of its anticipated adult brain size would make it somewhat larger-brained than australopithecines such as <em>Austalopithecus africanus<\/em>. The hand bones were capable of a precision grip like a human\u2019s hand. This increased the likelihood that stone tools found earlier at Olduvai Gorge were made by this group of hominins. Based on these findings, the authors inferred that it was a new species that should be classified in the genus <em>Homo<\/em>. They gave it the name <em>Homo habilis<\/em>, meaning \u201chandy\u201d or \u201cskilled.\u201d<\/span><\/p>\n<\/div>\n<figure id=\"attachment_316\" aria-describedby=\"caption-attachment-316\" style=\"width: 641px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-316\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/10.5.jpg\" alt=\"Two lateral right views of skulls and a jaw with blackened teeth.\" width=\"641\" height=\"214\" \/><figcaption id=\"caption-attachment-316\" class=\"wp-caption-text\">Figure 11.5a-c: Homo habilis fossil specimens. From left to right they are: a. lateral right view of OH-24 (found at Olduvai Gorge), b. lateral right view of KNM-ER-1813 (from Koobi Fora, Kenya), and c. the jaw of OH-7, which was the type specimen found in 1960 at Olduvai Gorge, Tanzania. Credit: a. <a href=\"https:\/\/efossils.org\/page\/boneviewer\/Homo%20habilis\/OH%2024\" target=\"_blank\">Homo habilis: OH 24 lateral right view<\/a> by \u00a9<a href=\"https:\/\/www.efossils.org\/\" target=\"_blank\">eFossils<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\" target=\"_blank\">CC BY-NC-SA 2.0 License<\/a> and is <a href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\" target=\"_blank\">used as outlined by eFossils<\/a>. b. <a href=\"https:\/\/www.efossils.org\/page\/boneviewer\/Homo%20habilis\/KNM-ER%201813\" target=\"_blank\">Homo habilis: KNM-ER 1813 lateral right view<\/a> by \u00a9<a href=\"https:\/\/www.efossils.org\/\" target=\"_blank\">eFossils<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\" target=\"_blank\">CC BY-NC-SA 2.0 License<\/a> and is <a href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\" target=\"_blank\">used as outlined by eFossils<\/a>. c. <a href=\"https:\/\/boneclones.com\/product\/homo-habilis-oh-7-jaw-KO-196\" target=\"_blank\">Homo habilis OH 7 Jaw<\/a> by<a href=\"https:\/\/boneclones.com\/\" target=\"_blank\"> \u00a9BoneClones<\/a> is used by permission and available here under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\"> CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<div class=\"__UNKNOWN__\">\n<h3 class=\"import-Normal\"><span style=\"color: #000000\"><strong>Controversies over the Classification of <\/strong><strong><em>Homo habilis<\/em><\/strong><em><br style=\"clear: both\" \/><\/em><\/span><\/h3>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Since its initial discovery, many more Homo habilis were discovered in East and South African sites during the 1970s and 1980s (Figure 11.6). As more fossils joined the ranks of <em>Homo habilis<\/em>, several trends became apparent. First, the fossils were quite variable. While some resembled the fossil specimen first published by Leakey and colleagues, others had larger cranial capacity and tooth size. A well-preserved fossil skull from East Lake Turkana labeled KNM-ER-1470 displayed a larger cranial size along with a strikingly wide face. The diversity of the <em>Homo habilis<\/em> fossils prompted some scientists to question whether they displayed too much variation to all belong to the same species. They proposed splitting the fossils into at least two groups. The first group resembling the original small-brained specimen would retain the species name <em>Homo habilis<\/em>; the second group consisting of the larger-brained fossils such as KNM-ER-1470 would be assigned the new name of <em>Homo rudolfensis <\/em>(see Figure 11.7). Researchers who favoured keeping all fossils in <em>Homo habilis<\/em> argued that sexual dimorphism, adaptation to local environments, or<strong> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1566\">developmental plasticity<\/a><\/strong> could be the cause of the differences. For example, modern human body size and body proportions are influenced by variations in climates and nutritional circumstances.<\/span><\/p>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 467.5pt;height: 367px\">\n<caption>Figure 11.6: Key Homo habilis fossil locations and the corresponding fossils and dates. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-15\/\" target=\"_blank\">Homo habilis table (Figure 10.6)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Bonnie Yoshida-Levine is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\"> CC BY-NC 4.0 License<\/a>.<\/caption>\n<thead>\n<tr style=\"height: 0\">\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 60px;width: 130.2px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Location of Fossils<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 60px;width: 52.7px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Dates<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 60px;width: 320.9px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong><br \/>\nDescription <\/strong><\/span><\/p>\n<p>&nbsp;<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 61px;width: 130.2px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Ledi-Gararu, Ethiopia<\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 61px;width: 52.7px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">2.8 mya<\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 61px;width: 320.9px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Partial lower jaw with evidence of both <em>Australopithecus<\/em> and <em>Homo<\/em> traits; tentatively considered oldest Early <em>Homo<\/em> fossil evidence.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 77px;width: 130.2px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Olduvai Gorge, Tanzania<\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 77px;width: 52.7px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">1.7 mya to 1.8 mya<\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 77px;width: 320.9px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Several different specimens classified as Homo habilis, including the type specimen found by Leakey, a relatively complete foot, and a skull with a cranial capacity of about 600 cc.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 93px;width: 130.2px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Koobi Fora, Lake Turkana Basin, Kenya<\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 93px;width: 52.7px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">1.9 mya<\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 93px;width: 320.9px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Several fossils from the Lake Turkana basin show considerable size differences, leading some anthropologists to classify the larger specimen (KNM-ER-1470) as a separate species,<em> Homo rudolfensis<\/em>.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 61px;width: 130.2px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Sterkfontein and other possible South African cave sites<\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 61px;width: 52.7px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">about 1.7 mya<\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 61px;width: 320.9px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">South African caves have yielded fragmentary remains identified as <em>Homo habilis<\/em>, but secure dates and specifics about the fossils are lacking.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr style=\"height: 15px\">\n<td style=\"height: 15px;width: 132.133px\"><\/td>\n<td style=\"height: 15px;width: 54.6333px\"><\/td>\n<td style=\"height: 15px;width: 322.333px\"><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<figure style=\"width: 228px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image10-1.jpg\" alt=\"Front view of black and white skull, missing lower jawbone.\" width=\"228\" height=\"228\" \/><figcaption class=\"wp-caption-text\">Figure 11.7: Cast of the Homo habilis cranium KNM-ER-1470. This cranium has a wide, flat face, larger brain size, and larger teeth than other Homo habilis fossils, leading some scientists to give it a separate species name, Homo rudolfensis. Credit: <a href=\"https:\/\/boneclones.com\/product\/homo-rudolfensis-skull-knm-er-1470-BH-013\" target=\"_blank\">Homo rudolfensis Cranium KNM-ER 1470<\/a> by<a href=\"https:\/\/boneclones.com\/\" target=\"_blank\"> \u00a9BoneClones<\/a> is used by permission and available here under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\"> CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Given the incomplete and fragmentary fossil record from this time period, it is not surprising that classification has proved contentious. As a scholarly consensus has not yet emerged on the classification status of early <em>Homo<\/em>, this chapter makes use of the single (inclusive) <em>Homo habilis<\/em> species designation.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">There is also disagreement on whether <em>Homo habilis<\/em> legitimately belongs in the genus <em>Homo<\/em>. Most of the fossils first classified as <em>Homo habilis<\/em> were skulls and teeth. When arm, leg, and foot bones were later found, making it possible to estimate body size, the specimens turned out to be quite small in stature with long arms and short legs. Analysis of the relative strength of limb bones suggested that the species, though bipedal, was much more adapted to arboreal climbing than <em>Homo erectus<\/em> and <em>Homo sapiens <\/em>(Ruff 2009). This has prompted some scientists to assert that <em>Homo habilis<\/em> behaved more like an australopithecine\u2014with a shorter gait and the ability to move around in the trees (Wood and Collard 1999). They were also skeptical of the claim that the brain size of <em>Homo habilis<\/em> was much larger than that of <em>Australopithecus<\/em>. They have proposed reclassifying some or all of the <em>Homo habilis<\/em> fossils into the genus <em>Australopithecus<\/em>, or even placing them into a newly created genus (Wood 2014).<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Other scholars have interpreted the fossil evidence differently. A recent reanalysis of <em>Homo habilis\/rudolfensis<\/em> fossils concluded that they sort into the genus <em>Homo<\/em> rather than <em>Australopithecus <\/em>(see Hominin Species Summaries at chapter end). In particular, statistical analysis performed indicates that the <em>Homo habilis<\/em> fossils differ significantly in average cranial capacity from the australopithecines. They also note that some australopithecine species such as the recently discovered <em>Australopithecus sediba<\/em> have relatively long legs, so body size may not have been as significant as brain- and tooth-size differences (Anton et al. 2014).<\/span><\/p>\n<div class=\"textbox\">\n<h2 class=\"import-Normal\"><span style=\"color: #000000\">Special Topic: Kamoya Kimeu<\/span><\/h2>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Kamoya Kimeu (1938\u20132022) is arguably the most prolific fossil hunter in the history of paleoanthropology (Figure 11.8). In addition to his many decades of work as a field excavator and project supervisor in East Africa, he also trained field workers and scholars and has served as curator for prehistoric sites for the National Museum of Kenya.<\/span><\/p>\n<figure style=\"width: 228px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image4-1.jpg\" alt=\"Man smiling at camera with lake and mountain in the background.\" width=\"228\" height=\"351\" \/><figcaption class=\"wp-caption-text\">Figure 11.8: Kamoya Kimeu (1938-2022). Credit: Photograph of Kamoya Kimeu by \u00a9Dr. Mark Teaford is used by permission.<\/figcaption><\/figure>\n<p><span style=\"color: #000000\">Kamoya Kimeu was born in 1938 in rural southeastern Kenya. Despite a formal education that did not go past the sixth grade, he had an aptitude for languages and familiarity with the plants and animals in the East African bush that led him to a job in Tanzania as a field excavator for Louis and Mary Leakey in 1960. In the years that followed, Kimeu found dozens of major hominin fossils. These included a <em>Paranthropus boisei <\/em>mandible at Olduvai Gorge, <em>Homo habilis <\/em>specimen KNM-ER-1813 from the Turkana Basin (shown in Figure 11.5), and a key early modern<em> Homo sapiens<\/em> fossil from the Omo Valley, Ethiopia. Kimeu\u2019s most famous fossil discovery was the skeleton of a young <em>Homo erectus<\/em> by the Nariokotome river bed in 1984. This finding was highly significant because it was a nearly complete early hominin skeleton and provided insight into child development within this species. In recognition of his work, Kimeu was awarded the National Geographic Society La Gorce Medal by U.S. President Ronald Reagan in 1985.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Traditionally, there has been a divide between African field workers and foreign research scientists, who would typically conduct seasonal field work in Africa, then travel back to their home institutions to publish their findings. Although Kimeu received widespread acclaim for the Nariokotome discovery, as well as a personal acknowledgement in the publication of the find in the journal <em>Nature<\/em>, he was not credited as an author. More recently, Kimeu\u2019s intellectual contributions to the field of paleoanthropology have been recognized. In 2021, he received an honorary doctorate degree from Case Western Reserve University in Ohio. Kimeu\u2019s most lasting legacy may be his mentorship of countless field workers and students. Today, there are a small but growing number of Black African paleoanthropologists taking on principal roles in the science of human origins.<\/span><\/p>\n<\/div>\n<h2 class=\"import-Normal\"><span style=\"color: #000000\"><em>Homo habilis<\/em> Culture and Lifeways<br \/>\n<\/span><\/h2>\n<h3 class=\"import-Normal\"><span style=\"color: #000000\"><strong>Early Stone Tools<\/strong><\/span><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">It is theorized that the larger brains and smaller teeth of early <em>Homo <\/em>are linked to a different adaptive strategy than that of earlier hominins: one dependent on modifying rocks to make stone tools and exploit new food sources. As discussed in Chapter 10, the 3.3-million-year-old stone tools from the Lomekwi 3 site in Kenya were made by earlier hominin species than <em>Homo<\/em>. However, stone tools become more frequent at sites dating to about 2 million years ago, the time of <em>Homo habilis <\/em>(Roche et al. 2009). This suggests that these hominins were increasingly reliant on stone tools to make a living.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Stone tools are assigned a good deal of importance in the study of human origins. Examining the form of the tools, the raw materials selected, and how they were made and used can provide insight into the thought processes of early humans and how they modified their environment in order to survive. Paleoanthropologists have traditionally classified collections of stone tools into industries, based on their form and mode of manufacture. There is not an exact correspondence between a tool industry and a hominin species; however, some general associations can be made between tool industries and particular hominins, locations, and time periods.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">The <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1394\">Oldowan<\/a><\/strong> tool industry is named after the site of Olduvai Gorge in Tanzania where the tools were first discovered. The time period of the Oldowan is generally estimated to be 2.5 mya to 1.6 mya. The tools of this industry are described as \u201cflake and chopper\u201d tools\u2014the choppers consisting of stone cobbles with a few flakes struck off them (Figure 11.9). To a casual observer, these tools might not look much different from randomly broken rocks. However, they are harder to make than their crude appearance suggests. The rock selected as the core must be struck by the rock serving as a hammerstone at just the right angle so that one or more flat flakes are removed. This requires selecting rocks that will fracture predictably instead of chunking, as well as the ability to plan ahead and envision the steps needed to create the finished product. The process leaves both the core and the flakes with sharp cutting edges that can be used for a variety of purposes.<\/span><\/p>\n<figure style=\"width: 505px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image11-1-1.png\" alt=\"Three stones with chunks missing from the tops and sides.\" width=\"505\" height=\"281\" \/><figcaption class=\"wp-caption-text\">Figure 11.9: Drawing of an Oldowan-style tool. This drawing shows a chopper; the flakes removed from the cores functioned as cutting tools. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Chopping_tool.gif\" target=\"_blank\">Chopping tool<\/a> by Jos\u00e9-Manuel Benito \u00c1lvarez is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.5\/legalcode\" target=\"_blank\">CC BY-SA 2.5 License<\/a>.<\/figcaption><\/figure>\n<h3 class=\"import-Normal\"><span style=\"color: #000000\"><strong>Stone Tool Use and the Diet of Early <\/strong><strong><em>Homo<\/em><\/strong><\/span><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">What were the hominins doing with the tools? One key activity seems to have been butchering animals. Studies of animal bones at the site show cut marks on bones, and leg bones are often cracked open, suggesting that they were extracting the marrow from the bone cavities. It is interesting to consider whether the hominins hunted these animals or acquired them through other means. The butchered bones come from a variety of African mammals, ranging from small antelope to animals as big as wildebeest and elephants! It is difficult to envision slow, small-bodied <em>Homo habilis<\/em> with their Oldowan tools bringing down such large animals. One possibility is that the hominins were scavenging carcasses from lions and other large cats. Paleoanthropologist Robert Blumenschine has investigated this hypothesis by observing the behaviour of present-day animal carnivores and scavengers on the African savanna. When lions abandon a kill after eating their fill, scavenging animals arrive almost immediately to pick apart the carcass. By the time slow-footed hominins arrived on the scene, the carcass would be mostly stripped of meat. However, if hominins could use stone tools to break into the leg bone cavities, they could get to the marrow, a fatty, calorie-dense source of protein (Blumenschine et al. 1987). Reconstructing activities that happened millions of years ago is obviously a difficult undertaking, and paleoanthropologists continue to debate whether scavenging or hunting was more commonly practiced during this time.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Regardless of how they were acquiring the meat, these activities suggest an important dietary shift from the way that the australopithecines were eating. The Oldowan toolmakers were exploiting a new ecological niche that provided them with more protein and calories. And it was not just limited to meat-eating\u2014stone tool use could have made available numerous other subsistence opportunities. A study of microscopic wear patterns on a sample of Oldowan tools indicates that they were used for processing plant materials such as wood, roots or tubers, and grass seeds and stems (Lemorini et al. 2014). In fact, it has been pointed out that the Oldowan toolmakers\u2019 cutting ability (whether for the purposes of consuming meat and plants or for making tools, shelters, or clothing) represents a new and unique innovation, never seen before in the natural world (Roche et al. 2009).<\/span><\/p>\n<h2 class=\"import-Normal\"><span style=\"color: #000000\"><em>Homo erectus<\/em>: Biological and Cultural Innovations<\/span><\/h2>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Two million years ago, a new hominin appeared on the scene. Known as <em>Homo erectus<\/em>, the prevailing scientific view was that this species was much more like us. These hominins were equipped with bigger brains and large bodies with limb proportions similar to our own. Perhaps most importantly, their way of life is now one that is recognizably human, with more advanced tools, hunting, use of fire, and colonizing new environments outside of Africa.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">As will be apparent below, new data suggests that the story is not quite as simple. The fossil record for <em>Homo erectus<\/em> is much more abundant than that of <em>Homo habilis<\/em>, but it is also more complex and varied\u2014both with regard to the fossils as well as the geographic context in which they are found.\u00a0<\/span><\/p>\n<h3 class=\"import-Normal\"><span style=\"color: #000000\"><strong><em>Homo erectus<\/em><\/strong><strong> Anatomy<\/strong><\/span><\/h3>\n<figure style=\"width: 289px\" class=\"wp-caption alignright\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image6-2.png\" alt=\"Lateral view of skull with large brow ridges.\" width=\"289\" height=\"289\" \/><figcaption class=\"wp-caption-text\">Figure 11.10: Replica of Homo erectus from Java, Indonesia. This cranium (known as Sangiran 17) dates to approximately 1.3 million to 1 million years ago. Note the large brow ridges and the occipital torus that gives the back of the skull a squared-off appearance. Credit: <a href=\"https:\/\/www.efossils.org\/page\/boneviewer\/Homo%20erectus\/Sangiran%2017\" target=\"_blank\">Homo erectus: Sangiran 17 lateral left view<\/a>\u00a0 by \u00a9<a href=\"https:\/\/www.efossils.org\/\" target=\"_blank\">eFossils<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\" target=\"_blank\">CC BY-NC-SA 2.0 License<\/a> and is <a href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\" target=\"_blank\">used as outlined by eFossils<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Compared to <em>Homo habilis<\/em>, <em>Homo erectus<\/em> showed increased brain size, smaller teeth, and a larger body. However, it also displayed key differences from later hominin species including our own. Although the head of <em>Homo erectus<\/em> was less ape-like in appearance than the australopithecines, it did not resemble modern humans (Figure 11.10). Compared to <em>Homo habilis<\/em>, <em>Homo erectus<\/em> had a larger brain size: an average of about 900 cc compared to 650 cc to 750 cc. Instead of a rounded shape like our skulls, the <em>erectus <\/em>skull was long and low like a football, with a receding forehead, and a horizontal ridge called an <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1552\">occipital torus<\/a><\/strong> that gave the back of the skull a squared-off appearance. The cranial bones are thicker than those of modern humans, and some <em>Homo erectus<\/em> skulls have a slight thickening along the sagittal suture called a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1553\">sagittal keel<\/a><\/strong>. Large, shelf-like brow ridges hang over the eyes. The face shows less <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1554\"> prognathism<\/a><\/strong>, and the back teeth are smaller than those of <em>Homo habilis. <\/em>Instead of a pointed chin, like ours, the mandible of <em>Homo erectus<\/em> recedes back.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Apart from these features, there is significant variation among <em>Homo <\/em><em>erectus<\/em> fossils from different regions. Scientists have long noted differences between the fossils from Africa and those from Indonesia and China. For example, the Asian fossils tend to have a thicker skull and larger brow ridges than the African specimens, and the sagittal keel described above is more pronounced. <em>Homo erectus<\/em> fossils from the Republic of Georgia (described in the next section) also display distinctive characteristics. As with <em>Homo habilis<\/em>, this diversity has prompted a classification debate about whether or not <em>Homo erectus<\/em> should be split into multiple species. When African <em>Homo erectus<\/em> is characterized as a separate species, it is called <em>Homo ergaster<\/em>, while the Asian variant retains the <em>erectus <\/em>species name because it was discovered first. Here, the species name <em>Homo erectus<\/em> will be used for both variants.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><em>Homo erectus<\/em> was thought to have a body size and proportions more similar to modern humans. Unlike <em>Homo habilis<\/em> and the australopithecines, both of whom were small-statured with long arms and short legs, <em>Homo erectus<\/em> shows evidence of being fully committed to life on the ground. This meant long, powerfully muscled legs that enabled these hominins to cover more ground efficiently. Indeed, studies of the <em>Homo erectus<\/em> body form have linked several characteristics of the species to long-distance running in the more open savanna environment (Bramble and Lieberman 2004). Many experts think that hominins around this time had lost much of their body hair, were particularly efficient at sweating, and had darker-pigmented skin\u2014all traits that would support the active lifestyle of such a large-bodied hominin.<\/span><\/p>\n<div class=\"__UNKNOWN__\">\n<div class=\"textbox\">\n<h2 class=\"import-Normal\"><span style=\"color: #000000\">Special Topic: How We Became Hairless, Sweaty Primates<\/span><\/h2>\n<p class=\"import-Normal\"><span style=\"color: #000000\">As an anthropology instructor teaching human evolution, my students often ask me about human body hair: When did our ancestors lose it and why? It is assumed that our earliest ancestors were as hairy as modern-day apes. Yet, today, we lack thick hair on most parts of our bodies except in the armpits, pubic regions, and tops of our heads. Humans actually have about the same number of hair follicles per unit of skin as chimpanzees, but, the hairs on most of our body are so thin as to be practically invisible. When did we develop this peculiar pattern of hairlessness? Which selective pressures in our ancestral environment were responsible for this unusual characteristic?<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Many experts believe that the driving force behind our loss of body hair was the need to effectively cool ourselves. Along with the lack of hair, humans are also distinguished by being exceptionally sweaty: we sweat larger quantities and more efficiently than any other primate. Humans have a larger amount of eccrine sweat glands than other primates and these glands generate an enormous volume of watery sweat. Sweating produces liquid on the skin that cools the body off as it evaporates. It seems likely that hairlessness and sweating evolved together, as a recent DNA analysis has identified a shared genetic pathway between hair follicles and eccrine sweat gland production (Kamberov et al. 2015).<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Which particular environmental conditions led to such adaptations? In this chapter, we learned that the climate was a driving force behind many changes seen in the hominin lineage during the Pleistocene. At that time, the climate was increasingly arid and the forest canopy in parts of Africa was being replaced with a more open grassland environment, resulting in increased sun exposure for our ancestors. Compared to the earlier australopithecines, members of the genus <em>Homo<\/em> were also developing larger bodies and brains, starting to obtain meat by hunting or scavenging carcasses, and crafting sophisticated stone tools.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">According to Nina Jablonski, an expert on the evolution of human skin, the loss of body hair and increased sweating capacity are part of the package of traits characterizing the genus <em>Homo<\/em>. While larger brains and long-legged bodies made it possible for humans to cover long distances while foraging, this new body form had to cool itself effectively to handle a more active lifestyle. Preventing the brain from overheating was especially critical. The ability to keep cool may have also enabled hominins to forage during the hottest part of the day, giving them an advantage over savanna predators, like lions, that typically rest during this time (Jablonski 2010).<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">When did these changes occur? Although hair and soft tissue do not typically fossilize, several indirect methods have been used to explore this question. One method tracks a human skin colour gene. Since chimpanzees have light skin under their hair, it is probable that early hominins also had light skin colour. Apes and other mammals with thick fur coats have protection against the sun\u2019s rays. As our ancestors lost their fur, it is likely that increased melanin pigmentation was selected for as a way to shield our ancestors from harmful ultraviolet radiation. A recent genetic analysis determined that one of the genes responsible for melanin production originated about 1.2 million years ago (Rogers et al 2004).<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Another line of evidence tracks the coevolution of a rather unpleasant human companion\u2014the louse. A genetic study identified human body louse as the youngest of the three varieties of lice that infest humans, splitting off as a distinct variety around 70,000 years ago (Kittler et al. 2003). Because human body lice can only spread through clothing, this may have been about the time when humans started to regularly wear clothing. However, the split between human head and pubic lice is estimated to have occurred much earlier, about three million years ago (Bower 2003; Reed et al. 2007). When humans lost much of their body hair, lice that used to roam freely around the body were now confined to two areas: the head and pubic region. As a result of this separation, the lice population split into two distinct groups.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Other explanations have been suggested for the loss of human body hair. For example, being hairless makes it more difficult for skin parasites like lice, fleas, and ticks to live on us. Additionally, after bipedality evolved, hairless bodies would also make reproductive organs and female breasts more visible, suggesting that sexual selection may have played a role.<\/span><\/p>\n<\/div>\n<\/div>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Much of the information about the body form of <em>Homo erectus<\/em> comes from the Nariokotome fossil of the <em>Homo erectus<\/em> youth, described at the beginning of the chapter (see Figure 11.1). However, <em>Homo erectus<\/em> fossils are turning out to be more varied than previously thought. <em>Homo erectus <\/em>fossils from sites in Africa, as well as from Dmanisi, Georgia, show smaller body sizes than the Nariokotome boy. Even the Nariokotome skeleton itself has been reassessed: some now predict he would have been about 5 feet and 4 inches when fully grown rather than over 6 feet as initially hypothesized, although there is still disagreement about which measurement is more accurate. One explanation for the range of body sizes could be adaptation to a range of different local environments, just as humans today show reduced body size in poor nutritional environments (Anton and Snodgrass 2012).<\/span><\/p>\n<h3 class=\"import-Normal\"><span style=\"color: #000000\"><strong><em>Homo erectus<\/em><\/strong><strong> in Africa <\/strong><\/span><\/h3>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Although the earliest discoveries of <em>Homo erectus<\/em> fossils were from Asia, the greatest quantity and best-preserved fossils of the species come from East African sites. The earliest fossils in Africa identified as <em>Homo erectus <\/em>come from the East African site of Koobi Fora, around Lake Turkana in Kenya, and are dated to about 1.8 million years ago. Other fossil remains have been found in East African sites in Kenya, Tanzania, and Ethiopia. Other notable African <em>Homo erectus<\/em> finds are a female pelvis from the site of Gona, Ethiopia (Simpson et al. 2008), and a cranium with massive brow ridges from Olduvai Gorge known as Olduvai 9, thought to be about 1.4 million years old.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Until recently, <em>Homo erectus<\/em>\u2019 presence in southern Africa has not been well documented. However, work at the Drimolen cave site in South Africa has yielded new fossils of <em>Paranthropus robustus<\/em>, and the cranium of a 2\u20133 year old child tentatively identified as <em>Homo erectus<\/em>, dated to about 2 million years (Herries et al. 2020). If substantiated, this would be the oldest discovery to date of <em>Homo erectus<\/em> anywhere.<\/span><\/p>\n<h3 class=\"import-Normal\"><span style=\"color: #000000\"><strong>Regional Discoveries Outside Africa<\/strong><\/span><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">It is generally agreed that<em> Homo erectus<\/em> was the first hominin to migrate out of Africa and colonize Asia and later Europe (although recent discoveries in Asia may challenge this view). Key locations and discoveries of <em>Homo erectus<\/em> fossils, along with the fossils\u2019 estimated ages, are summarized in Figures 11.11 and 11.12.<\/span><\/p>\n<figure style=\"width: 594px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image17-3.jpg\" alt=\"World map with England, Spain, Georgia, Kenya, China, and Java shaded.\" width=\"594\" height=\"459\" \/><figcaption class=\"wp-caption-text\">Figure 11.11:\u00a0 Map showing the locations of Homo erectus fossils around Africa and Eurasia. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\">A full text description of this image is available<\/a>. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-15\/\" target=\"_blank\">Homo erectus site map<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Chelsea Barron at<a href=\"https:\/\/www.csuchico.edu\/geop\/geoplace\/index.shtml\" target=\"_blank\"> GeoPlace, California State University, Chico<\/a> is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\"> CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 467.5pt\">\n<caption>Figure 11.12: Regional comparisons of Homo erectus fossils. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-15\/\" target=\"_blank\">Regional comparisons of Homo erectus fossils (Figure 10.12)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/caption>\n<thead>\n<tr style=\"height: 0\">\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Region<\/strong><\/span><\/p>\n<p>&nbsp;<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Sites<\/strong><\/span><\/p>\n<p>&nbsp;<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Dates<\/strong><\/span><\/p>\n<p>&nbsp;<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Significance of Fossils<\/strong><\/span><\/p>\n<p>&nbsp;<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">East Africa<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">East and West Lake Turkana, Kenya; Olduvai Gorge, Tanzania<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">1.8 to 1.4 mya<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Earliest evidence of <em>H. erectus<\/em>; significant variation in skull and facial features.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">South Africa<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Drimolen Cave, South Africa<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">2 mya<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Recent find of a 2\u20133 year old child would be oldest <em>H. erectus<\/em> anywhere to date.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Western<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Eurasia<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Dmanisi, Republic of Georgia<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">1.75 mya<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Smaller brains and bodies than <em>H. erectus<\/em> from other regions.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Western Europe<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Atapuerca, Spain (Sima del Elefante and Gran Dolina caves)<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">1.2 mya\u2013 400,000 ya<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Partial jaw from Atapuerca is oldest evidence of <em>H. erectus<\/em> in Western Europe.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Fossils from Gran Dolina (dated to about 800,000 years) sometimes referred to as <em>H. antecessor.<\/em><\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Indonesia<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Ngandong, Java; Sangiran, Java<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">1.6 mya<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Early dispersal of <em>H. erectus <\/em>to East Asia; Asian <em>H. erectus <\/em>features.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">China<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Zhoukoudian, China;<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Loess Plateau (Lantian)<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">780,000\u2013 400,000 ya;<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">2.1 mya<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Large sample of <em>H. erectus<\/em> fossils and artifacts.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Recent evidence of stone tools from Loess Plateau suggests great antiquity of <em>Homo<\/em> in East Asia.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<h4 class=\"import-Normal\"><span style=\"color: #000000\"><em>Indonesia<\/em><\/span><\/h4>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">The first discovery of<em> Homo erectus<\/em> was in the late 1800s in Java, Indonesia. A Dutch anatomist named Eugene Dubois searched for human fossils with the belief that since orangutans lived there, it might be a good place to look for remains of early humans. He discovered a portion of a skull, a femur, and other bone fragments on a riverbank. While the femur looked human, the top of the skull was smaller and thicker than that of a modern person. Dubois named the fossil <em>Pithecanthropus erectus<\/em> (\u201cupright ape-man\u201d), popularized in the media at the time as \u201cJava Man.\u201d After later discoveries of similar fossils in China and Africa, they were combined into a single species (retaining the <em>erectus<\/em> name) under the genus <em>Homo<\/em>.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Although <em>Homo erectus<\/em> has a long history in Indonesia, the region\u2019s geology has complicated the dating of fossils and sites. Fossils from the Sangiran Dome, Java, had previously been estimated to be as old as 1.8 million years, but scientists using new dating methods have arrived at a later date of about 1.3 mya (Matsu\u2019ura et al. 2020). On the recent end of the timeline, a cache of <em>H. erectus<\/em> fossils from the site of Ngandong in Java has yielded a surprisingly young date of 43,000 years, although a newer study with different dating methods concluded that they were between 117,000 to 108,000 years old (Rizal et al. 2020).<\/span><\/p>\n<h4 class=\"import-Normal\"><span style=\"color: #000000\"><em>China<\/em><\/span><\/h4>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">There is evidence of<em> Homo erectus <\/em>in China from several regions and time periods.<em> Homo erectus<\/em> fossils from northern China, collectively known as \u201cPeking Man,\u201d are some of the most famous human fossils in the world. Dated to about 400,000\u2013700,000 years ago, they were excavated from the site of Zhoukoudian, near the outskirts of Beijing. Hundreds of bones and teeth, including six nearly complete skulls, were excavated from a cave in the 1920s and 1930s. Much of the fossils\u2019 fame comes from the fact that they disappeared under mysterious circumstances. As Japan advanced into China during World War II, Chinese authorities, concerned for the security of the fossils, packed up the boxes and arranged for them to be transported to the United States. But in the chaos of the war, they vanished and were never heard about again. Fortunately, an anatomist named Frans Weidenreich had previously studied the bones and made casts and measurements of the skulls, so this valuable information was not lost. More recent excavations at Longgushan \u201cDragon Bone Cave\u201d at Zhoukoudian\u2014of tools, living sites, and food remains\u2014have revealed much about the lifestyle of <em>Homo erectus <\/em>during this time.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Despite this long history of research, China, compared to Africa, was perceived as somewhat peripheral to the study of hominin evolution. Although <em>Homo erectus<\/em> fossils have been found at several sites in China, with dates that make them comparable to those of Indonesian <em>Homo erectus<\/em>, none seemed to approximate the antiquity of African sites. The notable finds at sites like Nariokotome and Olorgesaille took centre stage during the 1970s and 1980s, as scientists focused on elucidating the species\u2019 anatomy and adaptations in its African homeland. In contrast, fewer research projects were focused on East Asian sites (Dennell and Roebroeks 2005; Qiu 2016).<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">However, isolated claims of very ancient hominin occupation kept cropping up from different locations in Asia. While some were dismissed because of problems with dating methods or stratigraphic context, the 2018 publication of the discovery of 2.1-million-year-old stone tools from China caught everyone\u2019s attention. Based on paleomagnetic techniques that date the associated soils and windblown dust, these tools indicate that hominins in Asia predated those from the Georgian site of Dmanisi by at least 300,000 years (Zhu et al. 2018). In fact, the tools are older than any <em>Homo erectus<\/em> fossils anywhere. Since no fossils were found with the tools, it isn\u2019t known which species made them, but it opens up the intriguing possibility that hominins could have migrated out of Africa earlier than <em>Homo erectus<\/em>. These new discoveries are shaking up previously held views of the East Asian human fossil record.<\/span><\/p>\n<h4 class=\"import-Normal\"><span style=\"color: #000000\"><em>Western Eurasia<\/em><\/span><\/h4>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">An extraordinary collection of fossils from the site of Dmanisi in the Republic of Georgia has revealed the presence of <em>Homo erectus<\/em> in Western Eurasia between 1.75 million and 1.86 million years ago. Dmanisi is located in the Caucasus mountains in Georgia. When archaeologists began excavating a medieval settlement near the town in the 1980s and came across the bones of extinct animals, they shifted their focus from the historic to the prehistoric era, but they probably did not anticipate going back quite so far in time. The first hominin fossils were discovered in the early 1990s, and since that time, at least five relatively well-preserved crania have been excavated.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">There are several surprising things about the Dmanisi fossils. Compared to African <em>Homo erectus,<\/em> they have smaller brains and bodies. However, despite the small brain size, they show clear signs of <em>Homo erectus<\/em> traits such as heavy brow ridges and reduced facial prognathism. Paleoanthropologists have pointed to some aspects of their anatomy (such as the shoulders) that appear rather primitive, although their body proportions seem fully committed to terrestrial bipedalism. One explanation for these differences could be that the Dmanisi hominins represent a very early form of <em>Homo erectus<\/em> that left Africa before increases in brain and body size evolved in the African population.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Second, although the fossils at this location are from the same geological context, they show a great deal of variation in brain size and in facial features. One skull (Skull 5) has a cranial capacity of only 550 cc, smaller than many <em>Homo habilis <\/em>fossils, along with larger teeth and a protruding face. Scientists disagree on what these differences mean. Some contend that the Dmanisi fossils cannot all belong to a single species because each one is so different. Others assert that the variability of the Dmanisi fossils proves that they, along with all early Homo fossils, including <em>H. habilis<\/em> and <em>H.<\/em><em>rudolfensis, <\/em>could <em>all <\/em>be grouped into <em>Homo erectus<\/em> (Lordkipanidze et al. 2013). Regardless of which point of view ends up dominating, the Dmanisi hominins are clearly central to the question of how to define the early members of the genus <em>Homo<\/em>.<\/span><\/p>\n<h4 class=\"import-Normal\"><span style=\"color: #000000\"><em>Europe<\/em><\/span><\/h4>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Until recently, there was scant evidence of any <em>Homo erectus<\/em> presence in Europe, and it was assumed that hominins did not colonize Europe until much later than East Asia or Eurasia. One explanation for this was that the harsh climate of Western Europe served as a barrier to settlement. However, recent fossil finds from Spain suggest that <em>Homo erectus<\/em> could have made it into Europe over a million years ago. In 2008 a mandible from the Atapuerca region in Spain was discovered, dating to about 1.2 million years ago. A more extensive assemblage of fossils from the site of Gran Dolina in Atapuerca have been dated to about 800,000 years ago. In England in 2013 fossilized hominin footprints of adults and children dated to 950,000 years ago were found at the site of Happisburgh, Norfolk, which would make them the oldest human footprints found outside Africa (Ashton et al. 2014).<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">At this time, researchers aren\u2019t in agreement as to whether the first Europeans belonged to <em>Homo erectus<\/em> proper or to a later descendent species. Some scientists refer to the early fossils from Spain by the species name <em>Homo antecessor<\/em>.<\/span><\/p>\n<\/div>\n<h2 class=\"__UNKNOWN__\"><span style=\"color: #000000\"><em>Homo erectus <\/em>Lifeways<\/span><\/h2>\n<div class=\"__UNKNOWN__\">\n<h3 class=\"import-Normal\"><span style=\"color: #000000\"><strong>Tool Technology: Acheulean Tool Industry<\/strong><\/span><\/h3>\n<figure style=\"width: 423px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image9-3.png\" alt=\"Front, back, side, and top views of oval-shaped stone core with chunks removed.\" width=\"423\" height=\"341\" \/><figcaption class=\"wp-caption-text\">Figure 11.13: Drawing of an Acheulean handaxe. This specimen is from Spain. When drawing a stone tool, artists typically show front and back faces, as well as top and side profiles. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Hand_axe_spanish.gif\" target=\"_blank\">Hand axe spanish<\/a> by<a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Locutus_Borg\" target=\"_blank\"> Jos\u00e9-Manuel Benito (user: Locutus Borg<\/a>) has been designated to the<a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/cc0\/\" target=\"_blank\"> public domain (CC0)<\/a>.<\/figcaption><\/figure>\n<p>In early African sites associated with <em>Homo erectus<\/em>, stone tools such as flakes and choppers identified to the Oldowan Industry dominate. Starting at about 1.5 million years ago, some <em>Homo erectus<\/em> populations began making different forms of tools. These tools\u2014classified together as constituting the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1556\">Acheulean <\/a><\/strong> tool industry\u2014are more complex in form and more consistent in their manufacture. Unlike the Oldowan tools, which were cobbles modified by striking off a few flakes, Acheulean toolmakers carefully shaped both sides of the tool. This type of technique, known as bifacial flaking, requires more planning and skill on the part of the toolmaker; he or she would need to be aware of principles of symmetry when crafting the tool. One of the most common tool forms, the handaxe, is shown in Figure 11.13. As with the tool illustrated below, handaxes tend to be thicker at the base and then come to a rounded point at the tip. Besides handaxes, forms such as scrapers, cleavers, and flake tools are present at <em>Homo erectus<\/em> sites.<\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">One striking aspect of Acheulean tools is their uniformity. They are more standardized in form and mode of manufacture than the earlier Oldowan tools. For example, the aforementioned handaxes vary in size, but they are remarkably consistent in regard to their shape and proportions. They were also an incredibly stable tool form over time\u2014lasting well over a million years with little change.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Curiously, the Acheulean tools so prominent at African sites are mostly absent in <em>Homo erectus<\/em> sites in East Asia. Instead, Oldowan-type choppers and scrapers are found at those sites. If this technology seemed to be so important to African <em>Homo erectus<\/em>, why didn\u2019t East Asian <em>Homo erectus<\/em> also use the tools? One reason could be environmental differences between the two regions. It has been suggested that <em>Asian Homo<\/em> <em>erectus<\/em> populations used perishable material such as bamboo to make tools. Another possibility is that <em>Homo erectus<\/em> (or even an earlier hominin) migrated to East Asia before the Acheulean technology developed in Africa. The recent discovery of the 2.1-million-year-old tools in China gives credence to this last explanation.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">What (if anything) do the Acheulean tools tell us about the mind of <em>Homo erectus<\/em>? Clearly, they took a fair amount of skill to manufacture. Apart from the actual shaping of the tool, other decisions made by toolmakers can reveal their use of foresight and planning. Did they just pick the most convenient rocks to make their tools, or did they search out a particular raw material that would be ideal for a particular tool? Analysis of Acheulean stone tools suggest that at some sites, the toolmakers selected their raw materials carefully\u2014traveling to particular rock outcrops to quarry stones and perhaps even removing large slabs of rock at the quarries to get at the most desirable material. Such complex activities would require advanced planning and communication with other individuals. However, other <em>Homo erectus<\/em> sites lack evidence of such selectivity; instead of traveling even a short distance for better raw material, the hominins tended to use what was available in their immediate area (Shipton et al. 2018).<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">In contrast to <em>Homo erectus<\/em> tools, the tools of early modern <em>Homo sapiens<\/em> during the Upper Paleolithic display tremendous diversity across regions and time periods. Additionally, Upper Paleolithic tools and artifacts communicate information such as status and group membership. Such innovation and social signaling seem to have been absent in <em>Homo erectus<\/em>, suggesting that they had a different relationship with their tools than did <em>Homo sapiens<\/em> (Coolidge and Wynn 2017). Some scientists assert that these contrasts in tool form and manufacture may signify key cognitive differences between the species, such as the ability to use a complex language.<\/span><\/p>\n<h3 class=\"import-Normal\"><span style=\"color: #000000\"><strong>Subsistence and Diet<\/strong><\/span><\/h3>\n<p class=\"import-Normal\"><span style=\"color: #000000\">In reconstructing the diet of <em>Homo erectus<\/em>, researchers can draw from multiple lines of evidence. These include stone tools used by <em>Homo erectus<\/em>, animal bones and occasionally plant remains from <em>Homo erectus<\/em> sites, and the bones and teeth of the fossils themselves. These data sources suggest that compared to the australopithecines, <em>Homo erectus<\/em> consumed more animal protein. Coinciding with the appearance of <em>Homo erectus<\/em> fossils in Africa are archaeological sites with much more abundant stone tools and larger concentrations of butchered animal bones.<\/span><\/p>\n<figure style=\"width: 253px\" class=\"wp-caption alignright\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image5-2.png\" alt=\"Five men excavating and note-taking at an archaeological site.\" width=\"253\" height=\"380\" \/><figcaption class=\"wp-caption-text\">Figure 11.14: Excavations at the site of Olorgesailie, Kenya. Dated from between 1.2 million years ago and 490,000 years ago, Olorgesailie has some of the most abundant and well-preserved evidence of Homo erectus activity in the world. Fossils of large mammals, such as elephants, along with thousands of Acheulean tools, have been uncovered over the decades. Credit: <a href=\"https:\/\/humanorigins.si.edu\/research\/olorgesailie-kenya\" target=\"_blank\">Elephant Butchery Site Olorgesailie, Kenya<\/a> by<a href=\"https:\/\/www.si.edu\/\" target=\"_blank\"> Smithsonian<\/a> [exhibit:<a href=\"https:\/\/humanorigins.si.edu\/research\" target=\"_blank\"> Human Evolution Research<\/a>,<a href=\"https:\/\/humanorigins.si.edu\/research\/east-african-research-projects\" target=\"_blank\"> East African Research Projects<\/a>, Olorgesailie, Kenya] is<a href=\"https:\/\/www.si.edu\/termsofuse\/\" target=\"_blank\"> copyrighted and used for educational and non-commercial purposes as outlined by the Smithsonian<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">It makes sense that a larger body and brain would be correlated with a dietary shift to more calorically dense foods. This is because the brain is a very energetically greedy organ. Indeed, our own human brains require more than 20% of one\u2019s calorie total intake to maintain. When biologists consider the evolution of intelligence in any animal species, it is often framed as a cost\/benefit analysis: For large brains to evolve, there has to be a compelling benefit to having them and a way to generate enough energy to fuel them.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">One solution that would allow for an increase in human brain size would be a corresponding reduction in the size of the digestive tract (gut). According to the \u201cexpensive tissue hypothesis,\u201d initially formulated by Leslie Aiello and Peter Wheeler (1995), a smaller gut would allow for a larger brain without the need for a corresponding increase in the organism\u2019s metabolic rate. More meat in the diet could also fuel the larger brain and body size seen in the genus <em>Homo<\/em>. Some researchers also believe that body fat percentages increased in hominins (particularly females) around this time, which would have allowed them to be better buffered against environmental disruption such as food shortages (Anton and Snodgrass 2012).<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">As indicated above, evidence from archaeology and the inferences about <em>Homo erectus<\/em> body size suggest increased meat eating. How much hunting did <em>Homo erectus<\/em> engage in compared to the earlier Oldowan toolmakers? Although experts continue to debate the relative importance of hunting versus scavenging, there seems to be stronger evidence of hunting for these hominins. For example, at sites such as Olorgesailie in Kenya (Figure 11.14), there are numerous associations of Acheulean tools with butchered remains of large animals.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">However, <em>Homo erectus<\/em> certainly ate more than just meat. Studies of the tooth surfaces and microscopic wear patterns on hominin teeth indicate that these hominins ate a variety of foods, including some hard, brittle plant foods (Unger and Scott 2009). This would make sense, considering the environment was changing to be more dominated by grasslands in some areas. Roots, bulbs, and tubers (known as underground storage organs) of open savanna plants may have been a primary food source. Indeed, hunter-gatherer groups such as the Hadza of Tanzania rely heavily on such foods, especially during periods when game is scarce. In the unstable environment of the early Pleistocene, dietary versatility would be a definite advantage.<\/span><\/p>\n<h3 class=\"import-Normal\"><span style=\"color: #000000\"><strong>Tool Use, Cooking, and Fire<\/strong><\/span><\/h3>\n<p class=\"import-Normal\"><span style=\"color: #000000\">One key characteristic of the genus <em>Homo<\/em> is smaller teeth compared to <em>Australopithecus<\/em>. Why would teeth get smaller? In addition to new types of foods, changes in how food was prepared and consumed likely led to a decrease in tooth size. Think about how you would eat if you didn\u2019t have access to cutting tools. What you couldn\u2019t rip apart with your hands would have to be bitten off with your teeth\u2014actions that would require bigger, more powerful teeth and jaws. As stone tools became increasingly important, researchers propose that hominins began to cut up, tenderize, and process meat and plants, such that they did not have to use their teeth so vigorously.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Cooking food could also have contributed to the reduction in tooth and jaw size. In fact, anthropologist Richard Wrangham (2009) asserts that cooking played a crucial role in human evolution. Cooking provides a head start in the digestive process because of how heat begins to break down food before food even enters the body, and it can help the body extract more nutrients out of meat and plant foods such as starchy tubers.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Obviously cooking requires fire, and the earliest use of fire is a fascinating topic in the study of human evolution. Fire is not only produced by humans; it occurs naturally as a result of lightning strikes. Like other wild animals, early hominins must have been terrified of wildfires, but at some point in time they learned to control fire and put it to good use. Documenting the earliest evidence of fire has been a contentious issue in archaeology because of the difficulty in distinguishing between human-controlled fire and natural burning at hominin sites. Burned areas and ash deposits must have direct associations with human activity to make a case for deliberate fire use. Unfortunately, such evidence is rare at ancient hominin sites, which have been profoundly altered by humans, animals, and geological forces over millions of years. Recently, newer methods\u2014including microscopic analysis of burned rock and bone\u2014have revealed clear evidence of fire use at Koobi Fora, Kenya, dating to 1.5 million years ago (Hlubik et al. 2017).<\/span><\/p>\n<h3 class=\"import-Normal\"><span style=\"color: #000000\"><strong>Migration out of Africa<\/strong><\/span><\/h3>\n<p class=\"import-Normal\"><span style=\"color: #000000\"><em>Homo erectus<\/em> is generally thought to be the first hominin species to have left Africa. It is hypothesized that they settled in places in Eurasia, such as the Republic of Georgia, Indonesia, and northern China, where fossil evidence of <em>Homo erectus<\/em> exists. But why would this species have traveled such vast distances to these far-flung regions? To answer this question, we have to consider what we have learned about the biology, culture, and environmental circumstances of <em>Homo erectus. <\/em>It is proposed that the larger brain and body size of <em>Homo erectus<\/em> were fuelled by a diet consisting of more meat, and their longer, more powerful legs made it possible to walk and run longer distances to acquire food. It is suggested that since they were eating higher on the food chain, it was necessary for them to extend their home range to find sufficient game. Cultural developments\u2014including better stone tools and new technology such as fire\u2014 might have given them greater flexibility in adapting to different environments. Finally, the major Pleistocene climate shift discussed earlier in the chapter certainly played a role. Changes in air temperature, precipitation, access to water sources, and other habitat alteration had far-reaching effects on animal and plant communities; this included <em>Homo erectus<\/em>. If hominins were relying more on hunting, the migration patterns of their prey could have led them to traverse increasingly long distances.<\/span><\/p>\n<h3 class=\"import-Normal\"><span style=\"color: #000000\"><strong>Life History<\/strong><\/span><\/h3>\n<p class=\"import-Normal\"><span style=\"color: #000000\">The <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1558\">life history <\/a><\/strong> of a species refers to its overall pattern of growth, development, and reproduction during its lifetime, with the assumption that these characteristics have been shaped by natural selection. The field of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1559\">human behavioural ecology<\/a><\/strong>, explored in more detail in Appendix C, examines the roots of human behaviour and life history. Our species, <em>Homo sapiens<\/em>, is characterized by a unique life history pattern of slow development, an extended period of juvenile dependence, and a long lifespan. Whereas the offspring of great apes achieve self-sufficiency early, human children are dependent on their parents long after weaning. Additionally, human fathers and grandparents (particularly postmenopausal grandmothers) devote substantial time and energy to caring for their children.<\/span><\/p>\n<figure style=\"width: 310px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image15-3.png\" alt=\"One man is shooting a bow and arrow; another man is carrying a bow with a dog beside him.\" width=\"310\" height=\"465\" \/><figcaption class=\"wp-caption-text\">Figure 11.15: Hadza men practice bowing. Native to Tanzania, the Hadza have retained many traditional foraging practices. Although most do not subsist entirely upon wild foods today, their way of life may shed light on how humans lived for most of their evolutionary history. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Hadzabe1.jpg\">Hadzabe1<\/a> by<a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Idobi\"> Idobi<\/a> is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\"> CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Human behavioural ecologists who study modern hunter-gatherer societies have observed that foraging is no easy business (Figure 11.15). Members of these groups engage in complex foraging techniques that take many years to master. An extended juvenile period gives children the time to acquire these skills. It also allows time for large human brains to grow and mature. On the back end, a longer developmental period results in skilled, successful adults, capable of living a long time (Hill and Kaplan 1999). Despite the time and energy demands, females could have offspring at more closely spaced intervals if they could depend on help from fathers and grandmothers (Hawkes et al. 1998).<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">What can the study of <em>Homo erectus<\/em> reveal about its life history pattern? Well-preserved fossils such as the Nariokotome boy can provide some insights. We know that apes such as chimpanzees reach maturity more quickly than humans, and there is some evidence that the australopithecines had a growth rate more akin to that of chimpanzees. Scientists have conducted extensive studies of the Nariokotome skeleton\u2019s bones and teeth to assess growth and development. On the one hand, examination of the long bone ends (epiphyses) of the skeleton suggested that he was an early adolescent with a relatively large body mass, though growth had not yet been completed. On the other hand, study of the dentition, including measurement of microscopic layers of tooth enamel called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1573\">perikymata<\/a><\/strong>, revealed a much younger age of 8 or 9. According to Christopher Dean and Holly Smith (2009), the best explanation for this discrepancy between the dental and skeletal age is that <em>Homo erectus<\/em> had its own distinct growth pattern\u2014reaching maturity more slowly than chimpanzees but faster than <em>Homo sapiens<\/em>. This suggests that the human life history pattern of slow maturation and lengthy dependency was a more recent development. More work remains on refining this pattern for early <em>Homo<\/em>, but it is an important topic that sheds light on how and when we developed our unique life history characteristics.<\/span><\/p>\n<h2 class=\"import-Normal\"><span style=\"color: #000000\">The Big Picture of Early <em>Homo<\/em><\/span><\/h2>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">We are discovering that the evolution of the genus <em>Homo<\/em> is more complex than what was previously thought. The earlier view of a simple progression from <em>Australopithecus<\/em> to <em>Homo habilis<\/em> to <em>Homo erectus<\/em> as clearly delineated stages in human evolution just doesn\u2019t hold up anymore.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">As is apparent from the information presented here, there is tremendous variability during this time. While fossils classified as <em>Homo habilis<\/em> show many of the characteristics of the genus <em>Homo<\/em>, such as brain expansion and smaller tooth size, the small body size and long arms are more akin to australopithecines. There is also tremendous variability within the fossils assigned to <em>Homo habilis<\/em>, so there is little consensus on whether it is one or multiple species of <em>Homo<\/em>, a member of the genus <em>Australopithecus<\/em>, or even a yet-to-be-defined new genus. Similarly, there are considerable differences in skull morphology and body size and form of <em>Homo erectus<\/em>, of which some specimens show more similarity to <em>Homo habilis<\/em> than previously thought.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">What does this diversity mean for how we should view early <em>Homo<\/em>? First, there isn\u2019t an abrupt break between <em>Australopithecus<\/em> and <em>Homo habilis<\/em> or even between <em>Homo habilis<\/em> and <em>Homo erectus<\/em>. Characteristics we define as <em>Homo<\/em> don\u2019t appear as a unified package; they appear in the fossil record at different times. This is known as <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1560\">mosaic evolution<\/a><\/strong>. Indeed, fossil species such as <em>Australopithecus sediba<\/em>, as well as <em>Homo naledi<\/em> and <em>Homo floresiensis<\/em> (who will be introduced in Chapter 12), have displayed unexpected combinations of primitive and derived traits.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">We can consider several explanations for the diversity we see within early <em>Homo<\/em> from about 2.5 million to 1.5 million years ago. One possibility is the existence of multiple contemporaneous species of early <em>Homo <\/em>during this period. In light of the pattern of environmental instability discussed earlier, it shouldn\u2019t be surprising to see fossils from different parts of Africa and Eurasia display tremendous variability. Multiple hominin forms could also evolve in the same region, as they diversified in order to occupy different ecological niches. However, even the presence of multiple species of hominin does not preclude their interacting and interbreeding with one another. As you\u2019ll see in Appendix D, sequencing of ancient hominin genomes has led to deeper understanding of genetic relationships between extinct species such as the Neanderthals and Denisovans.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Diversity of brain and body sizes could also reflect developmental plasticity\u2014short-term adaptations within a lifetime (Anton et al. 2014). These have the advantage of being more flexible than genetic natural selection, which could only occur over many generations. For example, among human populations today, different body sizes are thought to be adaptations to different climate or nutritional environments. Under Pleistocene conditions of intense variability, a more flexible strategy of adaptation would be valuable.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">New discoveries are also questioning old assumptions about the behaviour of <em>Homo habilis<\/em> and <em>Homo erectus<\/em>. Just as the fossil evidence doesn\u2019t neatly separate <em>Australopithecus<\/em> and <em>Homo<\/em>, evidence of the lifeways of early <em>Homo <\/em>show similar diversity. For example, one of the traditional dividing lines between <em>Homo <\/em>and <em>Australopithecus<\/em> was thought to be stone tools: <em>Homo<\/em> made them; <em>Australopithecus <\/em>didn\u2019t. However, the recent discovery of stone tools from Kenya dating to 3.3 million years ago challenges this point of view. Similarly, the belief that <em>Homo erectus<\/em> was the first species to settle outside Africa may now come into question with the report of 2.1-million-year-old stone tools from China. If this find is supported by additional evidence, it may cause a reevaluation of <em>Homo erectus<\/em> being the first to leave Africa. Instead, there could have been multiple earlier migrations of hominins such as <em>Homo habilis<\/em> or even <em>Australopithecus <\/em>species.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">These various lines of evidence about the genus <em>Homo <\/em>point out the need for a more nuanced view of this period of human evolution. Rather than obvious demarcations between species and their corresponding behavioural advancements, it now looks like many behaviours were shared among species. Earlier hominins that we previously didn\u2019t think had the capability could have been doing things like expanding out of Africa or using stone tools. Meanwhile, some other hominins that we had considered more advanced didn\u2019t actually have the full suite of \u201chuman\u201d characteristics previously expected.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">From a student\u2019s perspective, all this complexity probably seems frustrating. It would be ideal if the human story were a straightforward, sequential narrative. Unfortunately, it seems that human evolution was not a nice, neat trajectory of increasingly humanlike traits and behaviours; rather, it is emblematic of the untidy but exciting nature of the study of human evolution.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Despite some haziness dominating the early <em>Homo<\/em> narrative, we can identify some overall trends for the million-year period associated with early <em>Homo. <\/em>These trends include brain expansion, a reduction in facial prognathism, smaller jaw and tooth size, larger body size, and evidence of full terrestrial bipedalism. These traits are associated with a key behavioural shift that emphasizes culture as a flexible strategy to adapt to unpredictable environmental circumstances. Included in this repertoire are the creation and use of stone tools to process meat obtained by scavenging and later hunting, a utilization of fire and cooking, and the roots of the human life history pattern of prolonged childhood, cooperation in child raising, and the practice of skilled foraging techniques. In fact, it\u2019s apparent that the cultural innovations are driving the biological changes, and vice versa, fueling a feedback loop that continues during the later stages of human evolution.<\/span><\/p>\n<h2 class=\"import-Normal\"><span style=\"color: #000000\">Hominin Species Summaries<\/span><\/h2>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 344.15pt\">\n<tbody>\n<tr class=\"Table3-R\" style=\"height: 23pt\">\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Hominin<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><em>Homo habilis <\/em><\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 23pt\">\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Dates<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">2.5 million years ago to 1.7 million years ago<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 23pt\">\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Region(s)<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">East and South Africa<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 36pt\">\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Famous discoveries<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Olduvai Gorge, Tanzania; Koobi Fora, Kenya; Sterkfontein, South Africa<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 23pt\">\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Brain size<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">650 cc average (range from 510 cc to 775 cc)<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 23pt\">\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Dentition<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Smaller teeth with thinner enamel compared to <em>Australopithecus<\/em>; parabolic dental arcade shape<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 36pt\">\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Cranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Rounder cranium and less facial prognathism than <em>Australopithecus<\/em><\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 36pt\">\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Postcranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Small stature; similar body plan to <em>Australopithecus<\/em><\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 23pt\">\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Culture<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Oldowan tools<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 23pt\">\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Other<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">N\/A<\/span><\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 344.15pt\">\n<tbody>\n<tr class=\"Table4-R\" style=\"height: 23pt\">\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Hominin<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><em>Homo <\/em><em>erectus<\/em><\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 23pt\">\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Dates<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">1.8 million years ago to about 110,000 years ago<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 23pt\">\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Region(s)<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">East and South Africa; West Eurasia; China and Southeast Asia<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 36pt\">\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Famous discoveries<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Lake Turkana, Olorgesailie, Kenya; Java, Indonesia; Zhoukoudian, China; Dmanisi, Republic of Georgia<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 23pt\">\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Brain size<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Average 900 cc; range between 650 cc and 1,100 cc<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 23pt\">\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Dentition<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Smaller teeth than <em>Homo habilis<\/em><\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 36pt\">\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Cranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Long, low skull with robust features including thick cranial vault bones and large brow ridge, sagittal keel, and occipital torus<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 36pt\">\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Postcranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Larger body size compared to <em>Homo habilis<\/em>; body proportions (longer legs and shorter arms) similar to <em>Homo sapiens<\/em><\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 23pt\">\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Culture<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Acheulean tools (in Africa); evidence of increased hunting and meat-eating; use of fire; migration out of Africa<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 23pt\">\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Other<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">N\/A<\/span><\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div class=\"textbox shaded\">\n<h2 class=\"import-Normal\"><span style=\"color: #000000\">Review Questions<strong><br \/>\n<\/strong><\/span><\/h2>\n<ul>\n<li><span style=\"color: #000000\">Describe the climate during the early Pleistocene. Explain why climate is important for understanding the evolution of early <em>Homo<\/em>.<\/span><\/li>\n<li><span style=\"color: #000000\">List the key anatomical characteristics that are generally agreed to define the genus <em>Homo<\/em>.<\/span><\/li>\n<li><span style=\"color: #000000\">Why has classification of early<em> Homo <\/em>fossils proved difficult? What are some explanations for the variability seen in these fossils?<\/span><\/li>\n<li><span style=\"color: #000000\">Compare and contrast the Oldowan and Acheulean tool industries<em>.<\/em><\/span><\/li>\n<li><span style=\"color: #000000\">Name some specific behaviours associated with <em>Homo erectus<\/em> in the areas of tool use, subsistence practices, migration patterns, and other cultural innovations.<\/span><\/li>\n<\/ul>\n<\/div>\n<\/div>\n<h2 class=\"__UNKNOWN__\"><span style=\"color: #000000\">Key Terms<\/span><\/h2>\n<div class=\"__UNKNOWN__\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Acheulean<\/strong>: Tool industry characterized by teardrop-shaped stone handaxes flaked on both sides. <\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Developmental plasticity<\/strong>: The capability of an organism to modify its phenotype during development in response to environmental cues.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Human behavioural ecology<\/strong>: The study of human behaviour from an evolutionary and ecological perspective.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Life history<\/strong>: The broad pattern of a species\u2019 life cycle, including development, reproduction, and longevity.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Mosaic evolution<\/strong>: Different characteristics evolve at different rates and appear at different stages. <\/span><br style=\"clear: both\" \/><br style=\"clear: both\" \/><span style=\"color: #000000\"><strong>Occipital torus<\/strong>: A ridge on the occipital bone in the back of the skull.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Oldowan<\/strong>: Earliest stone-tool industry consisting of simple flakes and choppers.<\/span><br style=\"clear: both\" \/><span style=\"color: #000000\"><strong><br style=\"clear: both\" \/>Perikymata<\/strong>: Microscopic ridges on the surface of tooth enamel that serve as markers of tooth development.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Pleistocene<\/strong>: Geological epoch dating from 2.6 million years ago to about 11,000 years ago.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Pliocene:<\/strong> Geological epoch dating from 5.3 to 2.6 million years ago.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Prognathism<\/strong>: Condition where the lower face and jaw protrude forward from a vertical plane.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Sagittal keel<\/strong>: A thickened area along the top of the skull.<\/span><\/p>\n<\/div>\n<p><span style=\"color: #000000;font-family: Raleway, sans-serif;font-size: 1.5em\">FOR FURTHER EXPLORATION<\/span><\/p>\n<div class=\"__UNKNOWN__\">\n<p class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\">Boaz, Noel Thomas, and Russell L. Ciochon. 2004. <em>Dragon Bone Hill: An Ice-Age Saga of <\/em>Homo erectus. New York: Oxford University Press.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\"><a href=\"https:\/\/humanorigins.si.edu\/\">Human Evolution by the Smithsonian Institution<\/a>.\u00a0Produced by the Smithsonian National Museum of Natural History, this website covers many aspects of human evolution including 3-D models of hominin fossils.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\">Lewin, Roger, and Robert A. Foley. 2004. <em>Principles of Human Evolution<\/em>. Oxford, UK: Blackwell Publishing.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Mutu, Kari. \u201cHonour Finds Kenya\u2019s Oldest Fossil Hunter Kamoya Kimeu.\u201d <em>The East African<\/em>, July 19, 2021.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Nordling, Linda. \u201cRaising Up African Paleoanthropologists.\u201d <em>SAPIENS, <\/em>September 28, 2021. Accessed February 24, 2023. <a class=\"rId110\" style=\"color: #000000\" href=\"https:\/\/www.sapiens.org\/biology\/african-paleoanthropologists\/\"><em>https:\/\/www.sapiens.org\/biology\/african-paleoanthropologists\/<\/em><\/a>.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Risen, Clay. \u201cKamoya Kimeu, Fossil-Hunting \u2018Legend\u2019 in East Africa Is Dead.\u201d<em> New York Times<\/em>, August 11, 2022. Accessed February 24, 2023. https:\/\/www.nytimes.com\/2022\/08\/11\/science\/kamoya-kimeu-dead.html\/.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Stoneking, Mark. 2015. \u201cOf Lice and Men: The Molecular Evolution of Human Lice.\u201d Lecture, Center for Academic Research &amp; Training in Anthropogeny, San Diego, California, October 16, 2015. Accessed February 24, 2023. <a class=\"rId111\" style=\"color: #000000\" href=\"https:\/\/carta.anthropogeny.org\/events\/unique-features-human-skin\">https:\/\/carta.anthropogeny.org\/events\/unique-features-human-skin<\/a>.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\">Tarlach, Gemma. 2015. \u201cThe First Humans to Know Winter.\u201d <em>Discover<\/em>, February 26. https:\/\/www.discovermagazine.com\/planet-earth\/the-first-humans-to-know-winter<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Ungar, Peter S. 2017. <em>Evolution's Bite: A Story of Teeth, Diet, and Human Origins<\/em>. 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Kirchman. 2007. \"Pair of Lice Lost or Parasites Regained: The Evolutionary History of Anthropoid Primate Lice.\" <em>BMC Biology<\/em> 5 (1): 7. doi: 10.1186\/1741-7007-5-7.<\/span><\/p>\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 0pt;margin-right: 4pt;text-indent: 0pt\"><span style=\"color: #000000\">Rizal, Y., K. E. Westaway, Y. Zaim, G. D. van den Bergh, E. A. Bettis, 3rd, M. J. Morwood, O. F. Huffman, R. Gr\u00fcn, et al. 2020. \"Last Appearance of <em>Homo erectus<\/em> at Ngandong, Java, 117,000\u2013108,000 Years Ago.\" <em>Nature<\/em> 577 (7790): 381\u2013385.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\">Roche, Helene, Robert J. Blumenschine, and John J. Shea. 2009. \u201cOrigins and Adaptations of Early <em>Homo<\/em>: What Archeology Tells Us.\u201d In <em>The First Humans: Origin and Early Evolution of the Genus Homo<\/em>, edited by Frederick E. Grine, John G. Fleagle, and Richard E. Leakey, 135\u2013147. New York: Springer.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Rogers, Alan R., David Iltis, and Stephen Wooding. 2004. \u201cGenetic Variation at the MC1R l Locus and the Time since Loss of Human Body Hair.\u201d <em>Current Anthropology<\/em> 45 (1): 105\u2013108.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\">Ruff, Christopher. 2009. \u201cRelative Limb Strength and Locomotion in <em>Homo<\/em><em>habilis<\/em>.\u201d <em>American Journal of Physical Anthropology<\/em> 138 (1): 90\u2013100.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\">Shipton, Ceri, James Blinkhorn, Paul S. Breeze, Patrick Cuthbertson, Nick Drake, Huw S. Groucutt, Richard P. Jennings, et al. 2018. \u201cAcheulean Technology and Landscape Use at Dawadmi, Central Arabia.\u201d <em>PloS one<\/em> 13 (7): e0200497\u2013e0200497.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\">Simpson, Scott W., Jay Quade, Naomi E. Levin, Robert Butler, Guillaume Dupont-Nivet, Melanie Everett, and Sileshi Semaw. 2008. \u201cA Female <em>Homo<\/em><em>erectus<\/em> Pelvis from Gona, Ethiopia.\u201d <em>Science<\/em> 322 (5904): 1089\u20131092.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\">Ungar, Peter S., and Robert S. Scott. 2009. \u201cDental Evidence for Diets of Early <em>Homo<\/em>.\u201d In <em>The First Humans: Origin and Early Evolution of the Genus Homo<\/em>, edited by Frederick E. Grine, John G. Fleagle, and Richard E. Leakey, 121\u2013134. New York: Springer.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\">Villmoare, Brian, William H. Kimbel, Chalachew Seyoum, Christopher J. Campisano, Erin N. DiMaggio, John Rowan, David R. Braun, J. Ram\u00f3n Arrowsmith, and Kaye E. Reed. 2015. \u201cEarly <em>Homo<\/em> at 2.8 Ma From Ledi-Geraru, Afar, Ethiopia.\u201d <em>Science<\/em> 347 (6228): 1352\u20131355.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\">Wood, Bernard. 2014. \u201cHuman Evolution: Fifty Years after <em>Homo<\/em><em>habilis<\/em>.\u201d <em>Nature<\/em> 508 (7494): 31\u201333.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\">Wood, Bernard, and Mark Collard. 1999. \u201cThe Changing Face of Genus <em>Homo<\/em>.\u201d <em>Evolutionary Anthropology<\/em> 8 (6): 195\u2013207.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Wrangham, Richard. 2009. <em>Catching Fire: How Cooking Made Us Human<\/em>. New York: Basic Books.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\">Zhu, Zhaoyu, Robin Dennell, Weiwen Huang, Yi Wu, Shifan Qiu, Shixia Yang, and Zhiguo Rao. 2018. \u201cHominin Occupation of the Chinese Loess Plateau Since about 2.1 Million Years Ago.\u201d <em>Nature<\/em> 559: 608\u2013612.<\/span><\/p>\n<h2 class=\"import-Normal\"><span style=\"color: #000000\">Acknowledgements<br \/>\n<\/span><\/h2>\n<p class=\"import-Normal\"><span style=\"color: #000000\">The author gratefully acknowledges funding from the California Community Colleges Chancellor\u2019s Office Zero Textbook Cost Degree Grant Program\u2014Implementation Phase 2.<\/span><\/p>\n<\/div>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1695_1873\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1695_1873\"><div tabindex=\"-1\"><div class=\"__UNKNOWN__\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Bonnie Yoshida-Levine Ph.D., Grossmont College<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\"><em>This chapter is a revision from <\/em><em>\"<\/em><a class=\"rId7\" style=\"color: #000000\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-15\/\"><em>Chapter 10: Early Members of the Genus Homo<\/em><\/a><em>\" by Bonnie Yoshida-Levine. In <\/em><a class=\"rId8\" style=\"color: #000000\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\"><em>Explorations: An Open Invitation to Biological Anthropology, first edition<\/em><\/a><em>, edited by Beth Shook, Katie Nelson, Kelsie Aguilera, and Lara Braff, which is licensed under <\/em><a class=\"rId9\" style=\"color: #000000\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\"><em>CC BY-NC 4.0<\/em><\/a><em>.<\/em><\/span><\/p>\n<div class=\"textbox textbox--learning-objectives\">\n<header class=\"textbox__header\">\n<h2 class=\"textbox__title\">Learning Objectives<\/h2>\n<\/header>\n<div class=\"textbox__content\">\n<ul>\n<li>Describe how early Pleistocene climate change influenced the evolution of the genus Homo.<\/li>\n<li>Identify the characteristics that define the genus Homo.<\/li>\n<li>Describe the skeletal anatomy of Homo habilis\u00a0and Homo erectus based on the fossil evidence.<\/li>\n<li>Assess opposing points of view about how early Homo should be classified.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<p><span style=\"color: #000000\">The boy was no older than nine years when he perished by the swampy shores of the lake. After death, his slender, long-limbed body sank into the mud of the lake shallows. His bones fossilized and lay undisturbed for 1.5 million years. In the 1980s, fossil hunter Kamoya Kimeu, working on the western shore of Lake Turkana, Kenya, glimpsed a dark-coloured piece of bone eroding in a hillside. This small skull fragment led to the discovery of what is arguably the world\u2019s most complete early hominin fossil\u2014a youth identified as a member of the species <em>Homo erectus<\/em>. Now known as Nariokotome Boy, after the nearby lake village, the skeleton has provided a wealth of information about the early evolution of our own genus, <em>Homo <\/em>(see Figure 11.1). Today, a stone monument with an inscription in three languages\u2014English, Swahili, and the local Turkana language\u2014marks the site of this momentous fossil discovery.<\/span><\/p>\n<p><img class=\"aligncenter\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2023\/06\/image8-1.jpg\" alt=\"Front view of near-complete skeleton\" width=\"407\" height=\"407\" \/><\/p>\n<figure style=\"width: 405px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image13-1.jpg\" alt=\"Reconstructed head and shoulders of a young Homo erectus.\" width=\"405\" height=\"308\" \/><figcaption class=\"wp-caption-text\">Figure 11.1a-b: a. Skeleton of a young male Homo erectus known as \u201cNariokotome Boy\u201d; b. an artist\u2019s depiction of how he may have looked during his life. This is the most complete hominin fossil from this time period ever found. Credit: a.<a href=\"https:\/\/humanorigins.si.edu\/evidence\/human-fossils\/fossils\/knm-wt-15000\" target=\"_blank\"> KNM-WT 15000 Turkana Boy Skeleton<\/a> by<a href=\"https:\/\/www.si.edu\/\" target=\"_blank\"> Smithsonian<\/a> [exhibit:<a href=\"https:\/\/humanorigins.si.edu\/research\" target=\"_blank\"> Human Evolution<\/a> Evidence, Human Fossils, Fossils, KNM-WT 15000] is<a href=\"https:\/\/www.si.edu\/termsofuse\/\" target=\"_blank\"> copyrighted and used for educational and non-commercial purposes as outlined by the Smithsonian<\/a>. b. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Homo-erectus_Turkana-Boy_%28Ausschnitt%29_Fundort_Nariokotome,_Kenia,_Rekonstruktion_im_Neanderthal_Museum.jpg\" target=\"_blank\">Homo-erectus Turkana-Boy (Ausschnitt) Fundort Nariokotome, Kenia, Rekonstruktion im Neanderthal Museum<\/a> by Neanderthal Museum is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/deed.en\" target=\"_blank\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Chapter 10 described our oldest human ancestors, primarily members of the genus <em>Australopithecus<\/em>, who lived between 2 million and 4 million years ago. This chapter introduces the earliest members of the genus <em>Homo<\/em>, focusing on <em>Homo habilis<\/em> and <em>Homo erectus<\/em>.<\/span><\/p>\n<h2 class=\"import-Normal\"><span style=\"color: #000000\">Defining the Genus <em>Homo<\/em><\/span><\/h2>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Because Anthropology is fundamentally concerned with what makes us human, defining our own genus takes on special significance for anthropologists. Ever since scientists acknowledged the existence of extinct species of humans, they have debated which of them display sufficient \u201chumanness\u201d to merit classification in the genus <em>Homo<\/em>. When grouping species into a common genus, biologists consider criteria such as physical characteristics (morphology), evidence of recent common ancestry, and adaptive strategy (use of the environment). However, there is disagreement about which of those criteria should be prioritized, as well as how specific fossils should be interpreted in light of the criteria.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Nevertheless, there is general agreement that species classified as <em>Homo<\/em> should share characteristics that are broadly similar within our species. These include the following:<\/span><\/p>\n<ul>\n<li class=\"import-Normal\" style=\"background-color: transparent;text-align: left;text-indent: 18pt\"><span style=\"color: #000000\">a relatively large brain size<\/span><\/li>\n<li class=\"import-Normal\" style=\"background-color: transparent;text-align: left;text-indent: 18pt\"><span style=\"color: #000000\">a smaller and flatter face<\/span><\/li>\n<li class=\"import-Normal\" style=\"background-color: transparent;text-align: left;text-indent: 18pt\"><span style=\"color: #000000\">smaller jaws and teeth<\/span><\/li>\n<li class=\"import-Normal\" style=\"background-color: transparent;text-align: left;text-indent: 18pt\"><span style=\"color: #000000\">increased reliance on culture, particularly the use of stone tools, to exploit a greater diversity of environments (adaptive zone).<\/span><\/li>\n<\/ul>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Some researchers would include larger overall body size and limb proportions (longer legs\/shorter arms) in this list. While these criteria seem relatively clear-cut, evaluating them in the fossil record has proved more difficult, particularly for the earliest members of the genus. There are several reasons for this. First, many fossil specimens dating to this time period are incomplete and poorly preserved. Second, early <em>Homo<\/em> fossils appear quite variable in brain size, facial features, and teeth and body size, and there is not yet consensus about how to best make sense of this diversity. Finally, there is growing evidence that the evolution of the genus <em>Homo<\/em> proceeded in a mosaic pattern: in other words, these characteristics did not appear all at once in a single species; rather, they were patchily distributed in different species from different regions and time periods. Consequently, different researchers have come up with conflicting classification schemes depending on which criteria they think are most important.<\/span><\/p>\n<h2 class=\"import-Normal\"><span style=\"color: #000000\">Climate Change and Human Evolution<\/span><\/h2>\n<p class=\"import-Normal\"><span style=\"color: #000000\">A key goal in the study of human origins is to learn about the environmental pressures that may have shaped human evolution. As indicated in Chapter 8, scientists use a variety of techniques to reconstruct ancient environments. These include stable isotopes, core samples from oceans and lakes, windblown dust, analysis of geological formations and volcanoes, and fossils of ancient plant and animal communities. Such studies have provided valuable information about the environmental context of early <em>Homo<\/em>.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">The early hominin species covered in Chapter 10, such as <em>Ardipithecus ramidus<\/em> and <em>Australopithecus afarensis<\/em>, evolved during the late <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1404\">Pliocene<\/a><\/strong> epoch. The Pliocene (5.3 million to 2.6 million years ago) was marked by cooler and drier conditions, with ice caps forming permanently at the poles. Still, Earth\u2019s climate during the Pliocene was considerably warmer and wetter than at present.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">The subsequent <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1549\">Pleistocene<\/a> <\/strong>epoch (2.6 million years to 11,000 years ago) ushered in major environmental change. The Pleistocene is popularly referred to as the Ice Age. Since the term \u201cIce Age\u201d tends to conjure up images of glaciers and woolly mammoths, one would naturally assume that this was a period of uniformly cold climate around the globe. But this is not actually the case. Instead, climate became much more variable, cycling abruptly between warm\/wet (interglacial) and cold\/dry (glacial) cycles. These patterns were influenced by changes in Earth\u2019s elliptical orbit around the sun. As is shown in Figure 11.2, each cycle averaged about 41,000 years during the early Pleistocene; the cycles then lengthened to about 100,000 years starting around 1.25 million years ago. Since mountain ranges, wind patterns, ocean currents, and volcanic activity can all influence climate patterns, there were wide-ranging regional and local effects.<\/span><\/p>\n<figure style=\"width: 655px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image7-3.png\" alt=\"Graph depicts five million years of climate change from sediment cores.\" width=\"655\" height=\"197\" \/><figcaption class=\"wp-caption-text\">Figure 11.2: Temperature estimates during the last five million years, extrapolated from deep-sea core data. Lower temperatures and increased temperature oscillations start at 2.6 million years ago. Glacial\/interglacial cycles during the early part of the epoch are shorter, each averaging about 41,000 years. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Five_Myr_Climate_Change.png\" target=\"_blank\">Five Myr Climate Change<\/a> by<a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Dragons_flight\" target=\"_blank\"> Dragons flight<\/a> (Robert A. Rohde), based on data from Lisiechi and Raymo (2005), is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\"> CC BY-SA 3.0 License.<\/a><\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Data on ancient geography and climate help us understand how our ancestors moved and migrated to different parts of the world\u2014as well as the constraints under which they operated. When periods of global cooling dominated, sea levels were lower as more water was captured as glacial ice. This exposed continental margins and opened pathways between land masses. During glacial periods, the large Indonesian islands of Sumatra, Java, and Borneo were connected to the Southeast Asian mainland, while New Guinea was part of the southern landmass of greater Australia. There was a land bridge connection between Britain and continental Europe, and an icy, treeless plain known as Beringia connected Northern Asia and Alaska. At the same time, glaciation made some northern areas inaccessible to human habitation. For example, there is evidence that hominin species were in Britain 950,000 years ago, but it does not appear that Britain was continuously occupied during this period. It is speculated that these early humans may have died out or been forced to abandon the region during glacial periods.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">In Africa, paleoclimate research has determined that grasslands (shown in Figure 11.3) expanded and shrank multiple times during this period, even as they expanded over the long term (deMenocal 2014). From studies of fossils, paleontologists have been able to reconstruct Pleistocene animal communities and to consider how they were affected by the changing climate. Among the African animal populations, the number of grazing animal species such as antelope increased. Although the African and Eurasian continents are connected by land, the Sahara desert and the mountainous topography of North Africa serve as natural barriers to crossing. But the fossil record shows that at different times animal species have moved back and forth between Africa and Eurasia. During the early Pleistocene, there is evidence of African mammal species such as baboons, hippos, antelope, and African buffalo migrating out of Africa into Eurasia during periods of aridity (Belmaker 2010).<\/span><\/p>\n<figure style=\"width: 583px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image3-2.jpg\" alt=\"Dry grassy field with a few trees and mountains in the far distance.\" width=\"583\" height=\"406\" \/><figcaption class=\"wp-caption-text\">Figure 11.3: A savanna grassland in East Africa. Habitats such as this were becoming increasingly common during the Pleistocene. Credit: <a href=\"https:\/\/www.flickr.com\/photos\/ilri\/5130992564\" target=\"_blank\">Savanna grasslands of East Africa<\/a> by<a href=\"https:\/\/www.flickr.com\/photos\/ilri\/\" target=\"_blank\"> International Livestock Research Institute (ILRI)\/Elsworth<\/a> is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\" target=\"_blank\"> CC BY-NC-SA 2.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">This changing environment was undoubtedly challenging for our ancestors, but it offered new opportunities to make a living. It is theorized that one solution adopted by some hominins was to specialize in feeding on the new types of plants growing in this landscape. The robust australopithecines (described in Chapter 10) likely developed their large molar teeth with thick enamel in order to exploit this particular dietary niche.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Members of the genus <em>Homo <\/em>took a different route. Faced with the unstable African climate and shifting landscape, it is proposed that they evolved bigger brains that might have enabled them to rely on cultural solutions such as crafting stone tools that opened up new foraging opportunities. This strategy of behavioural flexibility might have served them well during this unpredictable time and may have led to new innovations such as increased meat-eating, cooperative hunting, and the exploitation of new environments outside Africa. <\/span><\/p>\n<h2 class=\"import-Normal\"><span style=\"color: #000000\"><em>Homo habilis<\/em>: The Earliest Members of Our Genus<\/span><\/h2>\n<p class=\"import-Normal\"><span style=\"color: #000000\"><em>Homo habilis<\/em> has traditionally been considered the earliest species placed in the genus <em>Homo<\/em>. However, as we will see, there is substantial disagreement among paleoanthropologists about the fossils classified as <em>Homo habilis<\/em>, including whether they come from a single species or multiple, or even whether they should be part of the genus <em>Homo <\/em>at all.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\"><em>Homo habilis<\/em> has a somewhat larger brain size\u2014an average of 650 cubic centimetres (cc)\u2014compared to <em>Australopithecus<\/em> with less than 500 cc. Additionally, the skull is more rounded and the face less prognathic. However, the postcranial remains show a body size and proportions similar to <em>Australopithecus<\/em>.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Known dates for fossils identified as <em>Homo habilis<\/em> range from about 2.5 million years ago to 1.7 million years ago. Recently, a partial lower jaw dated to 2.8 million years from the site of Ledi-Gararu in Ethiopia has been tentatively identified as belonging to the genus <em>Homo<\/em> (Villmoare et al. 2015). If this classification holds up, it would push the origins of our genus back even further.<\/span><\/p>\n<figure style=\"width: 554px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image16.jpg\" alt=\"Africa map with South Africa, Tanzania, Kenya, and Ethiopia shaded.\" width=\"554\" height=\"717\" \/><figcaption class=\"wp-caption-text\">Figure 11.4: Map showing major sites where <em>Homo habilis<\/em> fossils have been found. Ledi-Geraru is located in Ethiopia, Koobi Fora and Lake Turkana Basin are located in Kenya, the Olduvai Gorge is located in Tanzania, and Tuang, Malapa, Rising Star and Sterkfontein are located in South Africa. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-15\/\" target=\"_blank\">Homo habilis site map (Figure 10.4)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Chelsea Barron at<a href=\"https:\/\/www.csuchico.edu\/geop\/geoplace\/index.shtml\" target=\"_blank\"> GeoPlace, California State University, Chico<\/a> is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\"> CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\"><span style=\"color: #000000\">The first fossils to be named <em>Homo habilis<\/em> were discovered at the site of Olduvai Gorge in Tanzania, East Africa, by members of a team led by Louis and Mary Leakey (Figure 11.4). The Leakey family had been conducting fieldwork in the area since the 1930s and had discovered other hominin fossils at the site, such as the robust <em>Paranthropos boisei<\/em>. The key specimen, a juvenile individual, was actually found by their 20-year-old son Jonathan Leakey. Louis Leakey invited South African paleoanthropologist Philip Tobias and British anatomist John Napier to reconstruct and analyse the remains. The fossil of the juvenile shown in Figure 11.5 (now known as OH-7) consisted of a lower jaw, parts of the parietal bones of the skull, and some hand and finger bones. The fossil was dated by potassium-argon dating to about 1.75 million years. In 1964, the team published their findings in the scientific journal <em>Nature <\/em>(Leakey et al. 1964)<em>. <\/em>As described in the publication, the new fossils had smaller molar teeth that were less \u201cbulgy\u201d than australopithecine teeth. Although the primary specimen was not yet fully grown, an estimate of its anticipated adult brain size would make it somewhat larger-brained than australopithecines such as <em>Austalopithecus africanus<\/em>. The hand bones were capable of a precision grip like a human\u2019s hand. This increased the likelihood that stone tools found earlier at Olduvai Gorge were made by this group of hominins. Based on these findings, the authors inferred that it was a new species that should be classified in the genus <em>Homo<\/em>. They gave it the name <em>Homo habilis<\/em>, meaning \u201chandy\u201d or \u201cskilled.\u201d<\/span><\/p>\n<\/div>\n<figure id=\"attachment_316-2\" aria-describedby=\"caption-attachment-316-2\" style=\"width: 641px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-316\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/10.5.jpg\" alt=\"Two lateral right views of skulls and a jaw with blackened teeth.\" width=\"641\" height=\"214\" \/><figcaption id=\"caption-attachment-316-2\" class=\"wp-caption-text\">Figure 11.5a-c: Homo habilis fossil specimens. From left to right they are: a. lateral right view of OH-24 (found at Olduvai Gorge), b. lateral right view of KNM-ER-1813 (from Koobi Fora, Kenya), and c. the jaw of OH-7, which was the type specimen found in 1960 at Olduvai Gorge, Tanzania. Credit: a. <a href=\"https:\/\/efossils.org\/page\/boneviewer\/Homo%20habilis\/OH%2024\" target=\"_blank\">Homo habilis: OH 24 lateral right view<\/a> by \u00a9<a href=\"https:\/\/www.efossils.org\/\" target=\"_blank\">eFossils<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\" target=\"_blank\">CC BY-NC-SA 2.0 License<\/a> and is <a href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\" target=\"_blank\">used as outlined by eFossils<\/a>. b. <a href=\"https:\/\/www.efossils.org\/page\/boneviewer\/Homo%20habilis\/KNM-ER%201813\" target=\"_blank\">Homo habilis: KNM-ER 1813 lateral right view<\/a> by \u00a9<a href=\"https:\/\/www.efossils.org\/\" target=\"_blank\">eFossils<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\" target=\"_blank\">CC BY-NC-SA 2.0 License<\/a> and is <a href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\" target=\"_blank\">used as outlined by eFossils<\/a>. c. <a href=\"https:\/\/boneclones.com\/product\/homo-habilis-oh-7-jaw-KO-196\" target=\"_blank\">Homo habilis OH 7 Jaw<\/a> by<a href=\"https:\/\/boneclones.com\/\" target=\"_blank\"> \u00a9BoneClones<\/a> is used by permission and available here under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\"> CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<div class=\"__UNKNOWN__\">\n<h3 class=\"import-Normal\"><span style=\"color: #000000\"><strong>Controversies over the Classification of <\/strong><strong><em>Homo habilis<\/em><\/strong><em><br style=\"clear: both\" \/><\/em><\/span><\/h3>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Since its initial discovery, many more Homo habilis were discovered in East and South African sites during the 1970s and 1980s (Figure 11.6). As more fossils joined the ranks of <em>Homo habilis<\/em>, several trends became apparent. First, the fossils were quite variable. While some resembled the fossil specimen first published by Leakey and colleagues, others had larger cranial capacity and tooth size. A well-preserved fossil skull from East Lake Turkana labeled KNM-ER-1470 displayed a larger cranial size along with a strikingly wide face. The diversity of the <em>Homo habilis<\/em> fossils prompted some scientists to question whether they displayed too much variation to all belong to the same species. They proposed splitting the fossils into at least two groups. The first group resembling the original small-brained specimen would retain the species name <em>Homo habilis<\/em>; the second group consisting of the larger-brained fossils such as KNM-ER-1470 would be assigned the new name of <em>Homo rudolfensis <\/em>(see Figure 11.7). Researchers who favoured keeping all fossils in <em>Homo habilis<\/em> argued that sexual dimorphism, adaptation to local environments, or<strong> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1566\">developmental plasticity<\/a><\/strong> could be the cause of the differences. For example, modern human body size and body proportions are influenced by variations in climates and nutritional circumstances.<\/span><\/p>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 467.5pt;height: 367px\">\n<caption>Figure 11.6: Key Homo habilis fossil locations and the corresponding fossils and dates. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-15\/\" target=\"_blank\">Homo habilis table (Figure 10.6)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Bonnie Yoshida-Levine is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\"> CC BY-NC 4.0 License<\/a>.<\/caption>\n<thead>\n<tr style=\"height: 0\">\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 60px;width: 130.2px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Location of Fossils<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 60px;width: 52.7px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Dates<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 60px;width: 320.9px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong><br \/>\nDescription <\/strong><\/span><\/p>\n<p>&nbsp;<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 61px;width: 130.2px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Ledi-Gararu, Ethiopia<\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 61px;width: 52.7px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">2.8 mya<\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 61px;width: 320.9px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Partial lower jaw with evidence of both <em>Australopithecus<\/em> and <em>Homo<\/em> traits; tentatively considered oldest Early <em>Homo<\/em> fossil evidence.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 77px;width: 130.2px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Olduvai Gorge, Tanzania<\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 77px;width: 52.7px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">1.7 mya to 1.8 mya<\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 77px;width: 320.9px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Several different specimens classified as Homo habilis, including the type specimen found by Leakey, a relatively complete foot, and a skull with a cranial capacity of about 600 cc.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 93px;width: 130.2px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Koobi Fora, Lake Turkana Basin, Kenya<\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 93px;width: 52.7px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">1.9 mya<\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 93px;width: 320.9px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Several fossils from the Lake Turkana basin show considerable size differences, leading some anthropologists to classify the larger specimen (KNM-ER-1470) as a separate species,<em> Homo rudolfensis<\/em>.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 61px;width: 130.2px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Sterkfontein and other possible South African cave sites<\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 61px;width: 52.7px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">about 1.7 mya<\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 61px;width: 320.9px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">South African caves have yielded fragmentary remains identified as <em>Homo habilis<\/em>, but secure dates and specifics about the fossils are lacking.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr style=\"height: 15px\">\n<td style=\"height: 15px;width: 132.133px\"><\/td>\n<td style=\"height: 15px;width: 54.6333px\"><\/td>\n<td style=\"height: 15px;width: 322.333px\"><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<figure style=\"width: 228px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image10-1.jpg\" alt=\"Front view of black and white skull, missing lower jawbone.\" width=\"228\" height=\"228\" \/><figcaption class=\"wp-caption-text\">Figure 11.7: Cast of the Homo habilis cranium KNM-ER-1470. This cranium has a wide, flat face, larger brain size, and larger teeth than other Homo habilis fossils, leading some scientists to give it a separate species name, Homo rudolfensis. Credit: <a href=\"https:\/\/boneclones.com\/product\/homo-rudolfensis-skull-knm-er-1470-BH-013\" target=\"_blank\">Homo rudolfensis Cranium KNM-ER 1470<\/a> by<a href=\"https:\/\/boneclones.com\/\" target=\"_blank\"> \u00a9BoneClones<\/a> is used by permission and available here under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\"> CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Given the incomplete and fragmentary fossil record from this time period, it is not surprising that classification has proved contentious. As a scholarly consensus has not yet emerged on the classification status of early <em>Homo<\/em>, this chapter makes use of the single (inclusive) <em>Homo habilis<\/em> species designation.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">There is also disagreement on whether <em>Homo habilis<\/em> legitimately belongs in the genus <em>Homo<\/em>. Most of the fossils first classified as <em>Homo habilis<\/em> were skulls and teeth. When arm, leg, and foot bones were later found, making it possible to estimate body size, the specimens turned out to be quite small in stature with long arms and short legs. Analysis of the relative strength of limb bones suggested that the species, though bipedal, was much more adapted to arboreal climbing than <em>Homo erectus<\/em> and <em>Homo sapiens <\/em>(Ruff 2009). This has prompted some scientists to assert that <em>Homo habilis<\/em> behaved more like an australopithecine\u2014with a shorter gait and the ability to move around in the trees (Wood and Collard 1999). They were also skeptical of the claim that the brain size of <em>Homo habilis<\/em> was much larger than that of <em>Australopithecus<\/em>. They have proposed reclassifying some or all of the <em>Homo habilis<\/em> fossils into the genus <em>Australopithecus<\/em>, or even placing them into a newly created genus (Wood 2014).<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Other scholars have interpreted the fossil evidence differently. A recent reanalysis of <em>Homo habilis\/rudolfensis<\/em> fossils concluded that they sort into the genus <em>Homo<\/em> rather than <em>Australopithecus <\/em>(see Hominin Species Summaries at chapter end). In particular, statistical analysis performed indicates that the <em>Homo habilis<\/em> fossils differ significantly in average cranial capacity from the australopithecines. They also note that some australopithecine species such as the recently discovered <em>Australopithecus sediba<\/em> have relatively long legs, so body size may not have been as significant as brain- and tooth-size differences (Anton et al. 2014).<\/span><\/p>\n<div class=\"textbox\">\n<h2 class=\"import-Normal\"><span style=\"color: #000000\">Special Topic: Kamoya Kimeu<\/span><\/h2>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Kamoya Kimeu (1938\u20132022) is arguably the most prolific fossil hunter in the history of paleoanthropology (Figure 11.8). In addition to his many decades of work as a field excavator and project supervisor in East Africa, he also trained field workers and scholars and has served as curator for prehistoric sites for the National Museum of Kenya.<\/span><\/p>\n<figure style=\"width: 228px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image4-1.jpg\" alt=\"Man smiling at camera with lake and mountain in the background.\" width=\"228\" height=\"351\" \/><figcaption class=\"wp-caption-text\">Figure 11.8: Kamoya Kimeu (1938-2022). Credit: Photograph of Kamoya Kimeu by \u00a9Dr. Mark Teaford is used by permission.<\/figcaption><\/figure>\n<p><span style=\"color: #000000\">Kamoya Kimeu was born in 1938 in rural southeastern Kenya. Despite a formal education that did not go past the sixth grade, he had an aptitude for languages and familiarity with the plants and animals in the East African bush that led him to a job in Tanzania as a field excavator for Louis and Mary Leakey in 1960. In the years that followed, Kimeu found dozens of major hominin fossils. These included a <em>Paranthropus boisei <\/em>mandible at Olduvai Gorge, <em>Homo habilis <\/em>specimen KNM-ER-1813 from the Turkana Basin (shown in Figure 11.5), and a key early modern<em> Homo sapiens<\/em> fossil from the Omo Valley, Ethiopia. Kimeu\u2019s most famous fossil discovery was the skeleton of a young <em>Homo erectus<\/em> by the Nariokotome river bed in 1984. This finding was highly significant because it was a nearly complete early hominin skeleton and provided insight into child development within this species. In recognition of his work, Kimeu was awarded the National Geographic Society La Gorce Medal by U.S. President Ronald Reagan in 1985.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Traditionally, there has been a divide between African field workers and foreign research scientists, who would typically conduct seasonal field work in Africa, then travel back to their home institutions to publish their findings. Although Kimeu received widespread acclaim for the Nariokotome discovery, as well as a personal acknowledgement in the publication of the find in the journal <em>Nature<\/em>, he was not credited as an author. More recently, Kimeu\u2019s intellectual contributions to the field of paleoanthropology have been recognized. In 2021, he received an honorary doctorate degree from Case Western Reserve University in Ohio. Kimeu\u2019s most lasting legacy may be his mentorship of countless field workers and students. Today, there are a small but growing number of Black African paleoanthropologists taking on principal roles in the science of human origins.<\/span><\/p>\n<\/div>\n<h2 class=\"import-Normal\"><span style=\"color: #000000\"><em>Homo habilis<\/em> Culture and Lifeways<br \/>\n<\/span><\/h2>\n<h3 class=\"import-Normal\"><span style=\"color: #000000\"><strong>Early Stone Tools<\/strong><\/span><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">It is theorized that the larger brains and smaller teeth of early <em>Homo <\/em>are linked to a different adaptive strategy than that of earlier hominins: one dependent on modifying rocks to make stone tools and exploit new food sources. As discussed in Chapter 10, the 3.3-million-year-old stone tools from the Lomekwi 3 site in Kenya were made by earlier hominin species than <em>Homo<\/em>. However, stone tools become more frequent at sites dating to about 2 million years ago, the time of <em>Homo habilis <\/em>(Roche et al. 2009). This suggests that these hominins were increasingly reliant on stone tools to make a living.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Stone tools are assigned a good deal of importance in the study of human origins. Examining the form of the tools, the raw materials selected, and how they were made and used can provide insight into the thought processes of early humans and how they modified their environment in order to survive. Paleoanthropologists have traditionally classified collections of stone tools into industries, based on their form and mode of manufacture. There is not an exact correspondence between a tool industry and a hominin species; however, some general associations can be made between tool industries and particular hominins, locations, and time periods.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">The <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1394\">Oldowan<\/a><\/strong> tool industry is named after the site of Olduvai Gorge in Tanzania where the tools were first discovered. The time period of the Oldowan is generally estimated to be 2.5 mya to 1.6 mya. The tools of this industry are described as \u201cflake and chopper\u201d tools\u2014the choppers consisting of stone cobbles with a few flakes struck off them (Figure 11.9). To a casual observer, these tools might not look much different from randomly broken rocks. However, they are harder to make than their crude appearance suggests. The rock selected as the core must be struck by the rock serving as a hammerstone at just the right angle so that one or more flat flakes are removed. This requires selecting rocks that will fracture predictably instead of chunking, as well as the ability to plan ahead and envision the steps needed to create the finished product. The process leaves both the core and the flakes with sharp cutting edges that can be used for a variety of purposes.<\/span><\/p>\n<figure style=\"width: 505px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image11-1-1.png\" alt=\"Three stones with chunks missing from the tops and sides.\" width=\"505\" height=\"281\" \/><figcaption class=\"wp-caption-text\">Figure 11.9: Drawing of an Oldowan-style tool. This drawing shows a chopper; the flakes removed from the cores functioned as cutting tools. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Chopping_tool.gif\" target=\"_blank\">Chopping tool<\/a> by Jos\u00e9-Manuel Benito \u00c1lvarez is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.5\/legalcode\" target=\"_blank\">CC BY-SA 2.5 License<\/a>.<\/figcaption><\/figure>\n<h3 class=\"import-Normal\"><span style=\"color: #000000\"><strong>Stone Tool Use and the Diet of Early <\/strong><strong><em>Homo<\/em><\/strong><\/span><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">What were the hominins doing with the tools? One key activity seems to have been butchering animals. Studies of animal bones at the site show cut marks on bones, and leg bones are often cracked open, suggesting that they were extracting the marrow from the bone cavities. It is interesting to consider whether the hominins hunted these animals or acquired them through other means. The butchered bones come from a variety of African mammals, ranging from small antelope to animals as big as wildebeest and elephants! It is difficult to envision slow, small-bodied <em>Homo habilis<\/em> with their Oldowan tools bringing down such large animals. One possibility is that the hominins were scavenging carcasses from lions and other large cats. Paleoanthropologist Robert Blumenschine has investigated this hypothesis by observing the behaviour of present-day animal carnivores and scavengers on the African savanna. When lions abandon a kill after eating their fill, scavenging animals arrive almost immediately to pick apart the carcass. By the time slow-footed hominins arrived on the scene, the carcass would be mostly stripped of meat. However, if hominins could use stone tools to break into the leg bone cavities, they could get to the marrow, a fatty, calorie-dense source of protein (Blumenschine et al. 1987). Reconstructing activities that happened millions of years ago is obviously a difficult undertaking, and paleoanthropologists continue to debate whether scavenging or hunting was more commonly practiced during this time.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Regardless of how they were acquiring the meat, these activities suggest an important dietary shift from the way that the australopithecines were eating. The Oldowan toolmakers were exploiting a new ecological niche that provided them with more protein and calories. And it was not just limited to meat-eating\u2014stone tool use could have made available numerous other subsistence opportunities. A study of microscopic wear patterns on a sample of Oldowan tools indicates that they were used for processing plant materials such as wood, roots or tubers, and grass seeds and stems (Lemorini et al. 2014). In fact, it has been pointed out that the Oldowan toolmakers\u2019 cutting ability (whether for the purposes of consuming meat and plants or for making tools, shelters, or clothing) represents a new and unique innovation, never seen before in the natural world (Roche et al. 2009).<\/span><\/p>\n<h2 class=\"import-Normal\"><span style=\"color: #000000\"><em>Homo erectus<\/em>: Biological and Cultural Innovations<\/span><\/h2>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Two million years ago, a new hominin appeared on the scene. Known as <em>Homo erectus<\/em>, the prevailing scientific view was that this species was much more like us. These hominins were equipped with bigger brains and large bodies with limb proportions similar to our own. Perhaps most importantly, their way of life is now one that is recognizably human, with more advanced tools, hunting, use of fire, and colonizing new environments outside of Africa.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">As will be apparent below, new data suggests that the story is not quite as simple. The fossil record for <em>Homo erectus<\/em> is much more abundant than that of <em>Homo habilis<\/em>, but it is also more complex and varied\u2014both with regard to the fossils as well as the geographic context in which they are found.\u00a0<\/span><\/p>\n<h3 class=\"import-Normal\"><span style=\"color: #000000\"><strong><em>Homo erectus<\/em><\/strong><strong> Anatomy<\/strong><\/span><\/h3>\n<figure style=\"width: 289px\" class=\"wp-caption alignright\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image6-2.png\" alt=\"Lateral view of skull with large brow ridges.\" width=\"289\" height=\"289\" \/><figcaption class=\"wp-caption-text\">Figure 11.10: Replica of Homo erectus from Java, Indonesia. This cranium (known as Sangiran 17) dates to approximately 1.3 million to 1 million years ago. Note the large brow ridges and the occipital torus that gives the back of the skull a squared-off appearance. Credit: <a href=\"https:\/\/www.efossils.org\/page\/boneviewer\/Homo%20erectus\/Sangiran%2017\" target=\"_blank\">Homo erectus: Sangiran 17 lateral left view<\/a>\u00a0 by \u00a9<a href=\"https:\/\/www.efossils.org\/\" target=\"_blank\">eFossils<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\" target=\"_blank\">CC BY-NC-SA 2.0 License<\/a> and is <a href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\" target=\"_blank\">used as outlined by eFossils<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Compared to <em>Homo habilis<\/em>, <em>Homo erectus<\/em> showed increased brain size, smaller teeth, and a larger body. However, it also displayed key differences from later hominin species including our own. Although the head of <em>Homo erectus<\/em> was less ape-like in appearance than the australopithecines, it did not resemble modern humans (Figure 11.10). Compared to <em>Homo habilis<\/em>, <em>Homo erectus<\/em> had a larger brain size: an average of about 900 cc compared to 650 cc to 750 cc. Instead of a rounded shape like our skulls, the <em>erectus <\/em>skull was long and low like a football, with a receding forehead, and a horizontal ridge called an <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1552\">occipital torus<\/a><\/strong> that gave the back of the skull a squared-off appearance. The cranial bones are thicker than those of modern humans, and some <em>Homo erectus<\/em> skulls have a slight thickening along the sagittal suture called a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1553\">sagittal keel<\/a><\/strong>. Large, shelf-like brow ridges hang over the eyes. The face shows less <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1554\"> prognathism<\/a><\/strong>, and the back teeth are smaller than those of <em>Homo habilis. <\/em>Instead of a pointed chin, like ours, the mandible of <em>Homo erectus<\/em> recedes back.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Apart from these features, there is significant variation among <em>Homo <\/em><em>erectus<\/em> fossils from different regions. Scientists have long noted differences between the fossils from Africa and those from Indonesia and China. For example, the Asian fossils tend to have a thicker skull and larger brow ridges than the African specimens, and the sagittal keel described above is more pronounced. <em>Homo erectus<\/em> fossils from the Republic of Georgia (described in the next section) also display distinctive characteristics. As with <em>Homo habilis<\/em>, this diversity has prompted a classification debate about whether or not <em>Homo erectus<\/em> should be split into multiple species. When African <em>Homo erectus<\/em> is characterized as a separate species, it is called <em>Homo ergaster<\/em>, while the Asian variant retains the <em>erectus <\/em>species name because it was discovered first. Here, the species name <em>Homo erectus<\/em> will be used for both variants.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><em>Homo erectus<\/em> was thought to have a body size and proportions more similar to modern humans. Unlike <em>Homo habilis<\/em> and the australopithecines, both of whom were small-statured with long arms and short legs, <em>Homo erectus<\/em> shows evidence of being fully committed to life on the ground. This meant long, powerfully muscled legs that enabled these hominins to cover more ground efficiently. Indeed, studies of the <em>Homo erectus<\/em> body form have linked several characteristics of the species to long-distance running in the more open savanna environment (Bramble and Lieberman 2004). Many experts think that hominins around this time had lost much of their body hair, were particularly efficient at sweating, and had darker-pigmented skin\u2014all traits that would support the active lifestyle of such a large-bodied hominin.<\/span><\/p>\n<div class=\"__UNKNOWN__\">\n<div class=\"textbox\">\n<h2 class=\"import-Normal\"><span style=\"color: #000000\">Special Topic: How We Became Hairless, Sweaty Primates<\/span><\/h2>\n<p class=\"import-Normal\"><span style=\"color: #000000\">As an anthropology instructor teaching human evolution, my students often ask me about human body hair: When did our ancestors lose it and why? It is assumed that our earliest ancestors were as hairy as modern-day apes. Yet, today, we lack thick hair on most parts of our bodies except in the armpits, pubic regions, and tops of our heads. Humans actually have about the same number of hair follicles per unit of skin as chimpanzees, but, the hairs on most of our body are so thin as to be practically invisible. When did we develop this peculiar pattern of hairlessness? Which selective pressures in our ancestral environment were responsible for this unusual characteristic?<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Many experts believe that the driving force behind our loss of body hair was the need to effectively cool ourselves. Along with the lack of hair, humans are also distinguished by being exceptionally sweaty: we sweat larger quantities and more efficiently than any other primate. Humans have a larger amount of eccrine sweat glands than other primates and these glands generate an enormous volume of watery sweat. Sweating produces liquid on the skin that cools the body off as it evaporates. It seems likely that hairlessness and sweating evolved together, as a recent DNA analysis has identified a shared genetic pathway between hair follicles and eccrine sweat gland production (Kamberov et al. 2015).<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Which particular environmental conditions led to such adaptations? In this chapter, we learned that the climate was a driving force behind many changes seen in the hominin lineage during the Pleistocene. At that time, the climate was increasingly arid and the forest canopy in parts of Africa was being replaced with a more open grassland environment, resulting in increased sun exposure for our ancestors. Compared to the earlier australopithecines, members of the genus <em>Homo<\/em> were also developing larger bodies and brains, starting to obtain meat by hunting or scavenging carcasses, and crafting sophisticated stone tools.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">According to Nina Jablonski, an expert on the evolution of human skin, the loss of body hair and increased sweating capacity are part of the package of traits characterizing the genus <em>Homo<\/em>. While larger brains and long-legged bodies made it possible for humans to cover long distances while foraging, this new body form had to cool itself effectively to handle a more active lifestyle. Preventing the brain from overheating was especially critical. The ability to keep cool may have also enabled hominins to forage during the hottest part of the day, giving them an advantage over savanna predators, like lions, that typically rest during this time (Jablonski 2010).<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">When did these changes occur? Although hair and soft tissue do not typically fossilize, several indirect methods have been used to explore this question. One method tracks a human skin colour gene. Since chimpanzees have light skin under their hair, it is probable that early hominins also had light skin colour. Apes and other mammals with thick fur coats have protection against the sun\u2019s rays. As our ancestors lost their fur, it is likely that increased melanin pigmentation was selected for as a way to shield our ancestors from harmful ultraviolet radiation. A recent genetic analysis determined that one of the genes responsible for melanin production originated about 1.2 million years ago (Rogers et al 2004).<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Another line of evidence tracks the coevolution of a rather unpleasant human companion\u2014the louse. A genetic study identified human body louse as the youngest of the three varieties of lice that infest humans, splitting off as a distinct variety around 70,000 years ago (Kittler et al. 2003). Because human body lice can only spread through clothing, this may have been about the time when humans started to regularly wear clothing. However, the split between human head and pubic lice is estimated to have occurred much earlier, about three million years ago (Bower 2003; Reed et al. 2007). When humans lost much of their body hair, lice that used to roam freely around the body were now confined to two areas: the head and pubic region. As a result of this separation, the lice population split into two distinct groups.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Other explanations have been suggested for the loss of human body hair. For example, being hairless makes it more difficult for skin parasites like lice, fleas, and ticks to live on us. Additionally, after bipedality evolved, hairless bodies would also make reproductive organs and female breasts more visible, suggesting that sexual selection may have played a role.<\/span><\/p>\n<\/div>\n<\/div>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Much of the information about the body form of <em>Homo erectus<\/em> comes from the Nariokotome fossil of the <em>Homo erectus<\/em> youth, described at the beginning of the chapter (see Figure 11.1). However, <em>Homo erectus<\/em> fossils are turning out to be more varied than previously thought. <em>Homo erectus <\/em>fossils from sites in Africa, as well as from Dmanisi, Georgia, show smaller body sizes than the Nariokotome boy. Even the Nariokotome skeleton itself has been reassessed: some now predict he would have been about 5 feet and 4 inches when fully grown rather than over 6 feet as initially hypothesized, although there is still disagreement about which measurement is more accurate. One explanation for the range of body sizes could be adaptation to a range of different local environments, just as humans today show reduced body size in poor nutritional environments (Anton and Snodgrass 2012).<\/span><\/p>\n<h3 class=\"import-Normal\"><span style=\"color: #000000\"><strong><em>Homo erectus<\/em><\/strong><strong> in Africa <\/strong><\/span><\/h3>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Although the earliest discoveries of <em>Homo erectus<\/em> fossils were from Asia, the greatest quantity and best-preserved fossils of the species come from East African sites. The earliest fossils in Africa identified as <em>Homo erectus <\/em>come from the East African site of Koobi Fora, around Lake Turkana in Kenya, and are dated to about 1.8 million years ago. Other fossil remains have been found in East African sites in Kenya, Tanzania, and Ethiopia. Other notable African <em>Homo erectus<\/em> finds are a female pelvis from the site of Gona, Ethiopia (Simpson et al. 2008), and a cranium with massive brow ridges from Olduvai Gorge known as Olduvai 9, thought to be about 1.4 million years old.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Until recently, <em>Homo erectus<\/em>\u2019 presence in southern Africa has not been well documented. However, work at the Drimolen cave site in South Africa has yielded new fossils of <em>Paranthropus robustus<\/em>, and the cranium of a 2\u20133 year old child tentatively identified as <em>Homo erectus<\/em>, dated to about 2 million years (Herries et al. 2020). If substantiated, this would be the oldest discovery to date of <em>Homo erectus<\/em> anywhere.<\/span><\/p>\n<h3 class=\"import-Normal\"><span style=\"color: #000000\"><strong>Regional Discoveries Outside Africa<\/strong><\/span><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">It is generally agreed that<em> Homo erectus<\/em> was the first hominin to migrate out of Africa and colonize Asia and later Europe (although recent discoveries in Asia may challenge this view). Key locations and discoveries of <em>Homo erectus<\/em> fossils, along with the fossils\u2019 estimated ages, are summarized in Figures 11.11 and 11.12.<\/span><\/p>\n<figure style=\"width: 594px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image17-3.jpg\" alt=\"World map with England, Spain, Georgia, Kenya, China, and Java shaded.\" width=\"594\" height=\"459\" \/><figcaption class=\"wp-caption-text\">Figure 11.11:\u00a0 Map showing the locations of Homo erectus fossils around Africa and Eurasia. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\">A full text description of this image is available<\/a>. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-15\/\" target=\"_blank\">Homo erectus site map<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Chelsea Barron at<a href=\"https:\/\/www.csuchico.edu\/geop\/geoplace\/index.shtml\" target=\"_blank\"> GeoPlace, California State University, Chico<\/a> is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\"> CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 467.5pt\">\n<caption>Figure 11.12: Regional comparisons of Homo erectus fossils. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-15\/\" target=\"_blank\">Regional comparisons of Homo erectus fossils (Figure 10.12)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/caption>\n<thead>\n<tr style=\"height: 0\">\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Region<\/strong><\/span><\/p>\n<p>&nbsp;<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Sites<\/strong><\/span><\/p>\n<p>&nbsp;<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Dates<\/strong><\/span><\/p>\n<p>&nbsp;<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Significance of Fossils<\/strong><\/span><\/p>\n<p>&nbsp;<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">East Africa<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">East and West Lake Turkana, Kenya; Olduvai Gorge, Tanzania<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">1.8 to 1.4 mya<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Earliest evidence of <em>H. erectus<\/em>; significant variation in skull and facial features.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">South Africa<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Drimolen Cave, South Africa<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">2 mya<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Recent find of a 2\u20133 year old child would be oldest <em>H. erectus<\/em> anywhere to date.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Western<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Eurasia<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Dmanisi, Republic of Georgia<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">1.75 mya<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Smaller brains and bodies than <em>H. erectus<\/em> from other regions.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Western Europe<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Atapuerca, Spain (Sima del Elefante and Gran Dolina caves)<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">1.2 mya\u2013 400,000 ya<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Partial jaw from Atapuerca is oldest evidence of <em>H. erectus<\/em> in Western Europe.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Fossils from Gran Dolina (dated to about 800,000 years) sometimes referred to as <em>H. antecessor.<\/em><\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Indonesia<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Ngandong, Java; Sangiran, Java<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">1.6 mya<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Early dispersal of <em>H. erectus <\/em>to East Asia; Asian <em>H. erectus <\/em>features.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">China<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Zhoukoudian, China;<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Loess Plateau (Lantian)<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">780,000\u2013 400,000 ya;<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">2.1 mya<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Large sample of <em>H. erectus<\/em> fossils and artifacts.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Recent evidence of stone tools from Loess Plateau suggests great antiquity of <em>Homo<\/em> in East Asia.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<h4 class=\"import-Normal\"><span style=\"color: #000000\"><em>Indonesia<\/em><\/span><\/h4>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">The first discovery of<em> Homo erectus<\/em> was in the late 1800s in Java, Indonesia. A Dutch anatomist named Eugene Dubois searched for human fossils with the belief that since orangutans lived there, it might be a good place to look for remains of early humans. He discovered a portion of a skull, a femur, and other bone fragments on a riverbank. While the femur looked human, the top of the skull was smaller and thicker than that of a modern person. Dubois named the fossil <em>Pithecanthropus erectus<\/em> (\u201cupright ape-man\u201d), popularized in the media at the time as \u201cJava Man.\u201d After later discoveries of similar fossils in China and Africa, they were combined into a single species (retaining the <em>erectus<\/em> name) under the genus <em>Homo<\/em>.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Although <em>Homo erectus<\/em> has a long history in Indonesia, the region\u2019s geology has complicated the dating of fossils and sites. Fossils from the Sangiran Dome, Java, had previously been estimated to be as old as 1.8 million years, but scientists using new dating methods have arrived at a later date of about 1.3 mya (Matsu\u2019ura et al. 2020). On the recent end of the timeline, a cache of <em>H. erectus<\/em> fossils from the site of Ngandong in Java has yielded a surprisingly young date of 43,000 years, although a newer study with different dating methods concluded that they were between 117,000 to 108,000 years old (Rizal et al. 2020).<\/span><\/p>\n<h4 class=\"import-Normal\"><span style=\"color: #000000\"><em>China<\/em><\/span><\/h4>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">There is evidence of<em> Homo erectus <\/em>in China from several regions and time periods.<em> Homo erectus<\/em> fossils from northern China, collectively known as \u201cPeking Man,\u201d are some of the most famous human fossils in the world. Dated to about 400,000\u2013700,000 years ago, they were excavated from the site of Zhoukoudian, near the outskirts of Beijing. Hundreds of bones and teeth, including six nearly complete skulls, were excavated from a cave in the 1920s and 1930s. Much of the fossils\u2019 fame comes from the fact that they disappeared under mysterious circumstances. As Japan advanced into China during World War II, Chinese authorities, concerned for the security of the fossils, packed up the boxes and arranged for them to be transported to the United States. But in the chaos of the war, they vanished and were never heard about again. Fortunately, an anatomist named Frans Weidenreich had previously studied the bones and made casts and measurements of the skulls, so this valuable information was not lost. More recent excavations at Longgushan \u201cDragon Bone Cave\u201d at Zhoukoudian\u2014of tools, living sites, and food remains\u2014have revealed much about the lifestyle of <em>Homo erectus <\/em>during this time.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Despite this long history of research, China, compared to Africa, was perceived as somewhat peripheral to the study of hominin evolution. Although <em>Homo erectus<\/em> fossils have been found at several sites in China, with dates that make them comparable to those of Indonesian <em>Homo erectus<\/em>, none seemed to approximate the antiquity of African sites. The notable finds at sites like Nariokotome and Olorgesaille took centre stage during the 1970s and 1980s, as scientists focused on elucidating the species\u2019 anatomy and adaptations in its African homeland. In contrast, fewer research projects were focused on East Asian sites (Dennell and Roebroeks 2005; Qiu 2016).<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">However, isolated claims of very ancient hominin occupation kept cropping up from different locations in Asia. While some were dismissed because of problems with dating methods or stratigraphic context, the 2018 publication of the discovery of 2.1-million-year-old stone tools from China caught everyone\u2019s attention. Based on paleomagnetic techniques that date the associated soils and windblown dust, these tools indicate that hominins in Asia predated those from the Georgian site of Dmanisi by at least 300,000 years (Zhu et al. 2018). In fact, the tools are older than any <em>Homo erectus<\/em> fossils anywhere. Since no fossils were found with the tools, it isn\u2019t known which species made them, but it opens up the intriguing possibility that hominins could have migrated out of Africa earlier than <em>Homo erectus<\/em>. These new discoveries are shaking up previously held views of the East Asian human fossil record.<\/span><\/p>\n<h4 class=\"import-Normal\"><span style=\"color: #000000\"><em>Western Eurasia<\/em><\/span><\/h4>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">An extraordinary collection of fossils from the site of Dmanisi in the Republic of Georgia has revealed the presence of <em>Homo erectus<\/em> in Western Eurasia between 1.75 million and 1.86 million years ago. Dmanisi is located in the Caucasus mountains in Georgia. When archaeologists began excavating a medieval settlement near the town in the 1980s and came across the bones of extinct animals, they shifted their focus from the historic to the prehistoric era, but they probably did not anticipate going back quite so far in time. The first hominin fossils were discovered in the early 1990s, and since that time, at least five relatively well-preserved crania have been excavated.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">There are several surprising things about the Dmanisi fossils. Compared to African <em>Homo erectus,<\/em> they have smaller brains and bodies. However, despite the small brain size, they show clear signs of <em>Homo erectus<\/em> traits such as heavy brow ridges and reduced facial prognathism. Paleoanthropologists have pointed to some aspects of their anatomy (such as the shoulders) that appear rather primitive, although their body proportions seem fully committed to terrestrial bipedalism. One explanation for these differences could be that the Dmanisi hominins represent a very early form of <em>Homo erectus<\/em> that left Africa before increases in brain and body size evolved in the African population.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Second, although the fossils at this location are from the same geological context, they show a great deal of variation in brain size and in facial features. One skull (Skull 5) has a cranial capacity of only 550 cc, smaller than many <em>Homo habilis <\/em>fossils, along with larger teeth and a protruding face. Scientists disagree on what these differences mean. Some contend that the Dmanisi fossils cannot all belong to a single species because each one is so different. Others assert that the variability of the Dmanisi fossils proves that they, along with all early Homo fossils, including <em>H. habilis<\/em> and <em>H.<\/em><em>rudolfensis, <\/em>could <em>all <\/em>be grouped into <em>Homo erectus<\/em> (Lordkipanidze et al. 2013). Regardless of which point of view ends up dominating, the Dmanisi hominins are clearly central to the question of how to define the early members of the genus <em>Homo<\/em>.<\/span><\/p>\n<h4 class=\"import-Normal\"><span style=\"color: #000000\"><em>Europe<\/em><\/span><\/h4>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Until recently, there was scant evidence of any <em>Homo erectus<\/em> presence in Europe, and it was assumed that hominins did not colonize Europe until much later than East Asia or Eurasia. One explanation for this was that the harsh climate of Western Europe served as a barrier to settlement. However, recent fossil finds from Spain suggest that <em>Homo erectus<\/em> could have made it into Europe over a million years ago. In 2008 a mandible from the Atapuerca region in Spain was discovered, dating to about 1.2 million years ago. A more extensive assemblage of fossils from the site of Gran Dolina in Atapuerca have been dated to about 800,000 years ago. In England in 2013 fossilized hominin footprints of adults and children dated to 950,000 years ago were found at the site of Happisburgh, Norfolk, which would make them the oldest human footprints found outside Africa (Ashton et al. 2014).<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">At this time, researchers aren\u2019t in agreement as to whether the first Europeans belonged to <em>Homo erectus<\/em> proper or to a later descendent species. Some scientists refer to the early fossils from Spain by the species name <em>Homo antecessor<\/em>.<\/span><\/p>\n<\/div>\n<h2 class=\"__UNKNOWN__\"><span style=\"color: #000000\"><em>Homo erectus <\/em>Lifeways<\/span><\/h2>\n<div class=\"__UNKNOWN__\">\n<h3 class=\"import-Normal\"><span style=\"color: #000000\"><strong>Tool Technology: Acheulean Tool Industry<\/strong><\/span><\/h3>\n<figure style=\"width: 423px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image9-3.png\" alt=\"Front, back, side, and top views of oval-shaped stone core with chunks removed.\" width=\"423\" height=\"341\" \/><figcaption class=\"wp-caption-text\">Figure 11.13: Drawing of an Acheulean handaxe. This specimen is from Spain. When drawing a stone tool, artists typically show front and back faces, as well as top and side profiles. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Hand_axe_spanish.gif\" target=\"_blank\">Hand axe spanish<\/a> by<a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Locutus_Borg\" target=\"_blank\"> Jos\u00e9-Manuel Benito (user: Locutus Borg<\/a>) has been designated to the<a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/cc0\/\" target=\"_blank\"> public domain (CC0)<\/a>.<\/figcaption><\/figure>\n<p>In early African sites associated with <em>Homo erectus<\/em>, stone tools such as flakes and choppers identified to the Oldowan Industry dominate. Starting at about 1.5 million years ago, some <em>Homo erectus<\/em> populations began making different forms of tools. These tools\u2014classified together as constituting the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1556\">Acheulean <\/a><\/strong> tool industry\u2014are more complex in form and more consistent in their manufacture. Unlike the Oldowan tools, which were cobbles modified by striking off a few flakes, Acheulean toolmakers carefully shaped both sides of the tool. This type of technique, known as bifacial flaking, requires more planning and skill on the part of the toolmaker; he or she would need to be aware of principles of symmetry when crafting the tool. One of the most common tool forms, the handaxe, is shown in Figure 11.13. As with the tool illustrated below, handaxes tend to be thicker at the base and then come to a rounded point at the tip. Besides handaxes, forms such as scrapers, cleavers, and flake tools are present at <em>Homo erectus<\/em> sites.<\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">One striking aspect of Acheulean tools is their uniformity. They are more standardized in form and mode of manufacture than the earlier Oldowan tools. For example, the aforementioned handaxes vary in size, but they are remarkably consistent in regard to their shape and proportions. They were also an incredibly stable tool form over time\u2014lasting well over a million years with little change.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Curiously, the Acheulean tools so prominent at African sites are mostly absent in <em>Homo erectus<\/em> sites in East Asia. Instead, Oldowan-type choppers and scrapers are found at those sites. If this technology seemed to be so important to African <em>Homo erectus<\/em>, why didn\u2019t East Asian <em>Homo erectus<\/em> also use the tools? One reason could be environmental differences between the two regions. It has been suggested that <em>Asian Homo<\/em> <em>erectus<\/em> populations used perishable material such as bamboo to make tools. Another possibility is that <em>Homo erectus<\/em> (or even an earlier hominin) migrated to East Asia before the Acheulean technology developed in Africa. The recent discovery of the 2.1-million-year-old tools in China gives credence to this last explanation.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">What (if anything) do the Acheulean tools tell us about the mind of <em>Homo erectus<\/em>? Clearly, they took a fair amount of skill to manufacture. Apart from the actual shaping of the tool, other decisions made by toolmakers can reveal their use of foresight and planning. Did they just pick the most convenient rocks to make their tools, or did they search out a particular raw material that would be ideal for a particular tool? Analysis of Acheulean stone tools suggest that at some sites, the toolmakers selected their raw materials carefully\u2014traveling to particular rock outcrops to quarry stones and perhaps even removing large slabs of rock at the quarries to get at the most desirable material. Such complex activities would require advanced planning and communication with other individuals. However, other <em>Homo erectus<\/em> sites lack evidence of such selectivity; instead of traveling even a short distance for better raw material, the hominins tended to use what was available in their immediate area (Shipton et al. 2018).<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">In contrast to <em>Homo erectus<\/em> tools, the tools of early modern <em>Homo sapiens<\/em> during the Upper Paleolithic display tremendous diversity across regions and time periods. Additionally, Upper Paleolithic tools and artifacts communicate information such as status and group membership. Such innovation and social signaling seem to have been absent in <em>Homo erectus<\/em>, suggesting that they had a different relationship with their tools than did <em>Homo sapiens<\/em> (Coolidge and Wynn 2017). Some scientists assert that these contrasts in tool form and manufacture may signify key cognitive differences between the species, such as the ability to use a complex language.<\/span><\/p>\n<h3 class=\"import-Normal\"><span style=\"color: #000000\"><strong>Subsistence and Diet<\/strong><\/span><\/h3>\n<p class=\"import-Normal\"><span style=\"color: #000000\">In reconstructing the diet of <em>Homo erectus<\/em>, researchers can draw from multiple lines of evidence. These include stone tools used by <em>Homo erectus<\/em>, animal bones and occasionally plant remains from <em>Homo erectus<\/em> sites, and the bones and teeth of the fossils themselves. These data sources suggest that compared to the australopithecines, <em>Homo erectus<\/em> consumed more animal protein. Coinciding with the appearance of <em>Homo erectus<\/em> fossils in Africa are archaeological sites with much more abundant stone tools and larger concentrations of butchered animal bones.<\/span><\/p>\n<figure style=\"width: 253px\" class=\"wp-caption alignright\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image5-2.png\" alt=\"Five men excavating and note-taking at an archaeological site.\" width=\"253\" height=\"380\" \/><figcaption class=\"wp-caption-text\">Figure 11.14: Excavations at the site of Olorgesailie, Kenya. Dated from between 1.2 million years ago and 490,000 years ago, Olorgesailie has some of the most abundant and well-preserved evidence of Homo erectus activity in the world. Fossils of large mammals, such as elephants, along with thousands of Acheulean tools, have been uncovered over the decades. Credit: <a href=\"https:\/\/humanorigins.si.edu\/research\/olorgesailie-kenya\" target=\"_blank\">Elephant Butchery Site Olorgesailie, Kenya<\/a> by<a href=\"https:\/\/www.si.edu\/\" target=\"_blank\"> Smithsonian<\/a> [exhibit:<a href=\"https:\/\/humanorigins.si.edu\/research\" target=\"_blank\"> Human Evolution Research<\/a>,<a href=\"https:\/\/humanorigins.si.edu\/research\/east-african-research-projects\" target=\"_blank\"> East African Research Projects<\/a>, Olorgesailie, Kenya] is<a href=\"https:\/\/www.si.edu\/termsofuse\/\" target=\"_blank\"> copyrighted and used for educational and non-commercial purposes as outlined by the Smithsonian<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">It makes sense that a larger body and brain would be correlated with a dietary shift to more calorically dense foods. This is because the brain is a very energetically greedy organ. Indeed, our own human brains require more than 20% of one\u2019s calorie total intake to maintain. When biologists consider the evolution of intelligence in any animal species, it is often framed as a cost\/benefit analysis: For large brains to evolve, there has to be a compelling benefit to having them and a way to generate enough energy to fuel them.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">One solution that would allow for an increase in human brain size would be a corresponding reduction in the size of the digestive tract (gut). According to the \u201cexpensive tissue hypothesis,\u201d initially formulated by Leslie Aiello and Peter Wheeler (1995), a smaller gut would allow for a larger brain without the need for a corresponding increase in the organism\u2019s metabolic rate. More meat in the diet could also fuel the larger brain and body size seen in the genus <em>Homo<\/em>. Some researchers also believe that body fat percentages increased in hominins (particularly females) around this time, which would have allowed them to be better buffered against environmental disruption such as food shortages (Anton and Snodgrass 2012).<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">As indicated above, evidence from archaeology and the inferences about <em>Homo erectus<\/em> body size suggest increased meat eating. How much hunting did <em>Homo erectus<\/em> engage in compared to the earlier Oldowan toolmakers? Although experts continue to debate the relative importance of hunting versus scavenging, there seems to be stronger evidence of hunting for these hominins. For example, at sites such as Olorgesailie in Kenya (Figure 11.14), there are numerous associations of Acheulean tools with butchered remains of large animals.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">However, <em>Homo erectus<\/em> certainly ate more than just meat. Studies of the tooth surfaces and microscopic wear patterns on hominin teeth indicate that these hominins ate a variety of foods, including some hard, brittle plant foods (Unger and Scott 2009). This would make sense, considering the environment was changing to be more dominated by grasslands in some areas. Roots, bulbs, and tubers (known as underground storage organs) of open savanna plants may have been a primary food source. Indeed, hunter-gatherer groups such as the Hadza of Tanzania rely heavily on such foods, especially during periods when game is scarce. In the unstable environment of the early Pleistocene, dietary versatility would be a definite advantage.<\/span><\/p>\n<h3 class=\"import-Normal\"><span style=\"color: #000000\"><strong>Tool Use, Cooking, and Fire<\/strong><\/span><\/h3>\n<p class=\"import-Normal\"><span style=\"color: #000000\">One key characteristic of the genus <em>Homo<\/em> is smaller teeth compared to <em>Australopithecus<\/em>. Why would teeth get smaller? In addition to new types of foods, changes in how food was prepared and consumed likely led to a decrease in tooth size. Think about how you would eat if you didn\u2019t have access to cutting tools. What you couldn\u2019t rip apart with your hands would have to be bitten off with your teeth\u2014actions that would require bigger, more powerful teeth and jaws. As stone tools became increasingly important, researchers propose that hominins began to cut up, tenderize, and process meat and plants, such that they did not have to use their teeth so vigorously.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Cooking food could also have contributed to the reduction in tooth and jaw size. In fact, anthropologist Richard Wrangham (2009) asserts that cooking played a crucial role in human evolution. Cooking provides a head start in the digestive process because of how heat begins to break down food before food even enters the body, and it can help the body extract more nutrients out of meat and plant foods such as starchy tubers.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Obviously cooking requires fire, and the earliest use of fire is a fascinating topic in the study of human evolution. Fire is not only produced by humans; it occurs naturally as a result of lightning strikes. Like other wild animals, early hominins must have been terrified of wildfires, but at some point in time they learned to control fire and put it to good use. Documenting the earliest evidence of fire has been a contentious issue in archaeology because of the difficulty in distinguishing between human-controlled fire and natural burning at hominin sites. Burned areas and ash deposits must have direct associations with human activity to make a case for deliberate fire use. Unfortunately, such evidence is rare at ancient hominin sites, which have been profoundly altered by humans, animals, and geological forces over millions of years. Recently, newer methods\u2014including microscopic analysis of burned rock and bone\u2014have revealed clear evidence of fire use at Koobi Fora, Kenya, dating to 1.5 million years ago (Hlubik et al. 2017).<\/span><\/p>\n<h3 class=\"import-Normal\"><span style=\"color: #000000\"><strong>Migration out of Africa<\/strong><\/span><\/h3>\n<p class=\"import-Normal\"><span style=\"color: #000000\"><em>Homo erectus<\/em> is generally thought to be the first hominin species to have left Africa. It is hypothesized that they settled in places in Eurasia, such as the Republic of Georgia, Indonesia, and northern China, where fossil evidence of <em>Homo erectus<\/em> exists. But why would this species have traveled such vast distances to these far-flung regions? To answer this question, we have to consider what we have learned about the biology, culture, and environmental circumstances of <em>Homo erectus. <\/em>It is proposed that the larger brain and body size of <em>Homo erectus<\/em> were fuelled by a diet consisting of more meat, and their longer, more powerful legs made it possible to walk and run longer distances to acquire food. It is suggested that since they were eating higher on the food chain, it was necessary for them to extend their home range to find sufficient game. Cultural developments\u2014including better stone tools and new technology such as fire\u2014 might have given them greater flexibility in adapting to different environments. Finally, the major Pleistocene climate shift discussed earlier in the chapter certainly played a role. Changes in air temperature, precipitation, access to water sources, and other habitat alteration had far-reaching effects on animal and plant communities; this included <em>Homo erectus<\/em>. If hominins were relying more on hunting, the migration patterns of their prey could have led them to traverse increasingly long distances.<\/span><\/p>\n<h3 class=\"import-Normal\"><span style=\"color: #000000\"><strong>Life History<\/strong><\/span><\/h3>\n<p class=\"import-Normal\"><span style=\"color: #000000\">The <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1558\">life history <\/a><\/strong> of a species refers to its overall pattern of growth, development, and reproduction during its lifetime, with the assumption that these characteristics have been shaped by natural selection. The field of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1559\">human behavioural ecology<\/a><\/strong>, explored in more detail in Appendix C, examines the roots of human behaviour and life history. Our species, <em>Homo sapiens<\/em>, is characterized by a unique life history pattern of slow development, an extended period of juvenile dependence, and a long lifespan. Whereas the offspring of great apes achieve self-sufficiency early, human children are dependent on their parents long after weaning. Additionally, human fathers and grandparents (particularly postmenopausal grandmothers) devote substantial time and energy to caring for their children.<\/span><\/p>\n<figure style=\"width: 310px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image15-3.png\" alt=\"One man is shooting a bow and arrow; another man is carrying a bow with a dog beside him.\" width=\"310\" height=\"465\" \/><figcaption class=\"wp-caption-text\">Figure 11.15: Hadza men practice bowing. Native to Tanzania, the Hadza have retained many traditional foraging practices. Although most do not subsist entirely upon wild foods today, their way of life may shed light on how humans lived for most of their evolutionary history. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Hadzabe1.jpg\" target=\"_blank\">Hadzabe1<\/a> by<a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Idobi\" target=\"_blank\"> Idobi<\/a> is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\"> CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Human behavioural ecologists who study modern hunter-gatherer societies have observed that foraging is no easy business (Figure 11.15). Members of these groups engage in complex foraging techniques that take many years to master. An extended juvenile period gives children the time to acquire these skills. It also allows time for large human brains to grow and mature. On the back end, a longer developmental period results in skilled, successful adults, capable of living a long time (Hill and Kaplan 1999). Despite the time and energy demands, females could have offspring at more closely spaced intervals if they could depend on help from fathers and grandmothers (Hawkes et al. 1998).<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">What can the study of <em>Homo erectus<\/em> reveal about its life history pattern? Well-preserved fossils such as the Nariokotome boy can provide some insights. We know that apes such as chimpanzees reach maturity more quickly than humans, and there is some evidence that the australopithecines had a growth rate more akin to that of chimpanzees. Scientists have conducted extensive studies of the Nariokotome skeleton\u2019s bones and teeth to assess growth and development. On the one hand, examination of the long bone ends (epiphyses) of the skeleton suggested that he was an early adolescent with a relatively large body mass, though growth had not yet been completed. On the other hand, study of the dentition, including measurement of microscopic layers of tooth enamel called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1573\">perikymata<\/a><\/strong>, revealed a much younger age of 8 or 9. According to Christopher Dean and Holly Smith (2009), the best explanation for this discrepancy between the dental and skeletal age is that <em>Homo erectus<\/em> had its own distinct growth pattern\u2014reaching maturity more slowly than chimpanzees but faster than <em>Homo sapiens<\/em>. This suggests that the human life history pattern of slow maturation and lengthy dependency was a more recent development. More work remains on refining this pattern for early <em>Homo<\/em>, but it is an important topic that sheds light on how and when we developed our unique life history characteristics.<\/span><\/p>\n<h2 class=\"import-Normal\"><span style=\"color: #000000\">The Big Picture of Early <em>Homo<\/em><\/span><\/h2>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">We are discovering that the evolution of the genus <em>Homo<\/em> is more complex than what was previously thought. The earlier view of a simple progression from <em>Australopithecus<\/em> to <em>Homo habilis<\/em> to <em>Homo erectus<\/em> as clearly delineated stages in human evolution just doesn\u2019t hold up anymore.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">As is apparent from the information presented here, there is tremendous variability during this time. While fossils classified as <em>Homo habilis<\/em> show many of the characteristics of the genus <em>Homo<\/em>, such as brain expansion and smaller tooth size, the small body size and long arms are more akin to australopithecines. There is also tremendous variability within the fossils assigned to <em>Homo habilis<\/em>, so there is little consensus on whether it is one or multiple species of <em>Homo<\/em>, a member of the genus <em>Australopithecus<\/em>, or even a yet-to-be-defined new genus. Similarly, there are considerable differences in skull morphology and body size and form of <em>Homo erectus<\/em>, of which some specimens show more similarity to <em>Homo habilis<\/em> than previously thought.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">What does this diversity mean for how we should view early <em>Homo<\/em>? First, there isn\u2019t an abrupt break between <em>Australopithecus<\/em> and <em>Homo habilis<\/em> or even between <em>Homo habilis<\/em> and <em>Homo erectus<\/em>. Characteristics we define as <em>Homo<\/em> don\u2019t appear as a unified package; they appear in the fossil record at different times. This is known as <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1560\">mosaic evolution<\/a><\/strong>. Indeed, fossil species such as <em>Australopithecus sediba<\/em>, as well as <em>Homo naledi<\/em> and <em>Homo floresiensis<\/em> (who will be introduced in Chapter 12), have displayed unexpected combinations of primitive and derived traits.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">We can consider several explanations for the diversity we see within early <em>Homo<\/em> from about 2.5 million to 1.5 million years ago. One possibility is the existence of multiple contemporaneous species of early <em>Homo <\/em>during this period. In light of the pattern of environmental instability discussed earlier, it shouldn\u2019t be surprising to see fossils from different parts of Africa and Eurasia display tremendous variability. Multiple hominin forms could also evolve in the same region, as they diversified in order to occupy different ecological niches. However, even the presence of multiple species of hominin does not preclude their interacting and interbreeding with one another. As you\u2019ll see in Appendix D, sequencing of ancient hominin genomes has led to deeper understanding of genetic relationships between extinct species such as the Neanderthals and Denisovans.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Diversity of brain and body sizes could also reflect developmental plasticity\u2014short-term adaptations within a lifetime (Anton et al. 2014). These have the advantage of being more flexible than genetic natural selection, which could only occur over many generations. For example, among human populations today, different body sizes are thought to be adaptations to different climate or nutritional environments. Under Pleistocene conditions of intense variability, a more flexible strategy of adaptation would be valuable.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">New discoveries are also questioning old assumptions about the behaviour of <em>Homo habilis<\/em> and <em>Homo erectus<\/em>. Just as the fossil evidence doesn\u2019t neatly separate <em>Australopithecus<\/em> and <em>Homo<\/em>, evidence of the lifeways of early <em>Homo <\/em>show similar diversity. For example, one of the traditional dividing lines between <em>Homo <\/em>and <em>Australopithecus<\/em> was thought to be stone tools: <em>Homo<\/em> made them; <em>Australopithecus <\/em>didn\u2019t. However, the recent discovery of stone tools from Kenya dating to 3.3 million years ago challenges this point of view. Similarly, the belief that <em>Homo erectus<\/em> was the first species to settle outside Africa may now come into question with the report of 2.1-million-year-old stone tools from China. If this find is supported by additional evidence, it may cause a reevaluation of <em>Homo erectus<\/em> being the first to leave Africa. Instead, there could have been multiple earlier migrations of hominins such as <em>Homo habilis<\/em> or even <em>Australopithecus <\/em>species.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">These various lines of evidence about the genus <em>Homo <\/em>point out the need for a more nuanced view of this period of human evolution. Rather than obvious demarcations between species and their corresponding behavioural advancements, it now looks like many behaviours were shared among species. Earlier hominins that we previously didn\u2019t think had the capability could have been doing things like expanding out of Africa or using stone tools. Meanwhile, some other hominins that we had considered more advanced didn\u2019t actually have the full suite of \u201chuman\u201d characteristics previously expected.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">From a student\u2019s perspective, all this complexity probably seems frustrating. It would be ideal if the human story were a straightforward, sequential narrative. Unfortunately, it seems that human evolution was not a nice, neat trajectory of increasingly humanlike traits and behaviours; rather, it is emblematic of the untidy but exciting nature of the study of human evolution.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Despite some haziness dominating the early <em>Homo<\/em> narrative, we can identify some overall trends for the million-year period associated with early <em>Homo. <\/em>These trends include brain expansion, a reduction in facial prognathism, smaller jaw and tooth size, larger body size, and evidence of full terrestrial bipedalism. These traits are associated with a key behavioural shift that emphasizes culture as a flexible strategy to adapt to unpredictable environmental circumstances. Included in this repertoire are the creation and use of stone tools to process meat obtained by scavenging and later hunting, a utilization of fire and cooking, and the roots of the human life history pattern of prolonged childhood, cooperation in child raising, and the practice of skilled foraging techniques. In fact, it\u2019s apparent that the cultural innovations are driving the biological changes, and vice versa, fueling a feedback loop that continues during the later stages of human evolution.<\/span><\/p>\n<h2 class=\"import-Normal\"><span style=\"color: #000000\">Hominin Species Summaries<\/span><\/h2>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 344.15pt\">\n<tbody>\n<tr class=\"Table3-R\" style=\"height: 23pt\">\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Hominin<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><em>Homo habilis <\/em><\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 23pt\">\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Dates<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">2.5 million years ago to 1.7 million years ago<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 23pt\">\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Region(s)<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">East and South Africa<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 36pt\">\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Famous discoveries<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Olduvai Gorge, Tanzania; Koobi Fora, Kenya; Sterkfontein, South Africa<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 23pt\">\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Brain size<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">650 cc average (range from 510 cc to 775 cc)<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 23pt\">\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Dentition<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Smaller teeth with thinner enamel compared to <em>Australopithecus<\/em>; parabolic dental arcade shape<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 36pt\">\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Cranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Rounder cranium and less facial prognathism than <em>Australopithecus<\/em><\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 36pt\">\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Postcranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Small stature; similar body plan to <em>Australopithecus<\/em><\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 23pt\">\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Culture<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Oldowan tools<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 23pt\">\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Other<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">N\/A<\/span><\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 344.15pt\">\n<tbody>\n<tr class=\"Table4-R\" style=\"height: 23pt\">\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Hominin<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><em>Homo <\/em><em>erectus<\/em><\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 23pt\">\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Dates<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">1.8 million years ago to about 110,000 years ago<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 23pt\">\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Region(s)<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">East and South Africa; West Eurasia; China and Southeast Asia<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 36pt\">\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Famous discoveries<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Lake Turkana, Olorgesailie, Kenya; Java, Indonesia; Zhoukoudian, China; Dmanisi, Republic of Georgia<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 23pt\">\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Brain size<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Average 900 cc; range between 650 cc and 1,100 cc<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 23pt\">\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Dentition<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Smaller teeth than <em>Homo habilis<\/em><\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 36pt\">\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Cranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Long, low skull with robust features including thick cranial vault bones and large brow ridge, sagittal keel, and occipital torus<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 36pt\">\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Postcranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Larger body size compared to <em>Homo habilis<\/em>; body proportions (longer legs and shorter arms) similar to <em>Homo sapiens<\/em><\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 23pt\">\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Culture<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Acheulean tools (in Africa); evidence of increased hunting and meat-eating; use of fire; migration out of Africa<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 23pt\">\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Other<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">N\/A<\/span><\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div class=\"textbox shaded\">\n<h2 class=\"import-Normal\"><span style=\"color: #000000\">Review Questions<strong><br \/>\n<\/strong><\/span><\/h2>\n<ul>\n<li><span style=\"color: #000000\">Describe the climate during the early Pleistocene. Explain why climate is important for understanding the evolution of early <em>Homo<\/em>.<\/span><\/li>\n<li><span style=\"color: #000000\">List the key anatomical characteristics that are generally agreed to define the genus <em>Homo<\/em>.<\/span><\/li>\n<li><span style=\"color: #000000\">Why has classification of early<em> Homo <\/em>fossils proved difficult? What are some explanations for the variability seen in these fossils?<\/span><\/li>\n<li><span style=\"color: #000000\">Compare and contrast the Oldowan and Acheulean tool industries<em>.<\/em><\/span><\/li>\n<li><span style=\"color: #000000\">Name some specific behaviours associated with <em>Homo erectus<\/em> in the areas of tool use, subsistence practices, migration patterns, and other cultural innovations.<\/span><\/li>\n<\/ul>\n<\/div>\n<\/div>\n<h2 class=\"__UNKNOWN__\"><span style=\"color: #000000\">Key Terms<\/span><\/h2>\n<div class=\"__UNKNOWN__\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Acheulean<\/strong>: Tool industry characterized by teardrop-shaped stone handaxes flaked on both sides. <\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Developmental plasticity<\/strong>: The capability of an organism to modify its phenotype during development in response to environmental cues.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Human behavioural ecology<\/strong>: The study of human behaviour from an evolutionary and ecological perspective.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Life history<\/strong>: The broad pattern of a species\u2019 life cycle, including development, reproduction, and longevity.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Mosaic evolution<\/strong>: Different characteristics evolve at different rates and appear at different stages. <\/span><br style=\"clear: both\" \/><br style=\"clear: both\" \/><span style=\"color: #000000\"><strong>Occipital torus<\/strong>: A ridge on the occipital bone in the back of the skull.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Oldowan<\/strong>: Earliest stone-tool industry consisting of simple flakes and choppers.<\/span><br style=\"clear: both\" \/><span style=\"color: #000000\"><strong><br style=\"clear: both\" \/>Perikymata<\/strong>: Microscopic ridges on the surface of tooth enamel that serve as markers of tooth development.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Pleistocene<\/strong>: Geological epoch dating from 2.6 million years ago to about 11,000 years ago.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Pliocene:<\/strong> Geological epoch dating from 5.3 to 2.6 million years ago.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Prognathism<\/strong>: Condition where the lower face and jaw protrude forward from a vertical plane.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Sagittal keel<\/strong>: A thickened area along the top of the skull.<\/span><\/p>\n<\/div>\n<p><span style=\"color: #000000;font-family: Raleway, sans-serif;font-size: 1.5em\">FOR FURTHER EXPLORATION<\/span><\/p>\n<div class=\"__UNKNOWN__\">\n<p class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\">Boaz, Noel Thomas, and Russell L. Ciochon. 2004. <em>Dragon Bone Hill: An Ice-Age Saga of <\/em>Homo erectus. New York: Oxford University Press.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\"><a href=\"https:\/\/humanorigins.si.edu\/\" target=\"_blank\">Human Evolution by the Smithsonian Institution<\/a>.\u00a0Produced by the Smithsonian National Museum of Natural History, this website covers many aspects of human evolution including 3-D models of hominin fossils.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\">Lewin, Roger, and Robert A. Foley. 2004. <em>Principles of Human Evolution<\/em>. Oxford, UK: Blackwell Publishing.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Mutu, Kari. \u201cHonour Finds Kenya\u2019s Oldest Fossil Hunter Kamoya Kimeu.\u201d <em>The East African<\/em>, July 19, 2021.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Nordling, Linda. \u201cRaising Up African Paleoanthropologists.\u201d <em>SAPIENS, <\/em>September 28, 2021. Accessed February 24, 2023. <a class=\"rId110\" style=\"color: #000000\" href=\"https:\/\/www.sapiens.org\/biology\/african-paleoanthropologists\/\" target=\"_blank\"><em>https:\/\/www.sapiens.org\/biology\/african-paleoanthropologists\/<\/em><\/a>.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Risen, Clay. \u201cKamoya Kimeu, Fossil-Hunting \u2018Legend\u2019 in East Africa Is Dead.\u201d<em> New York Times<\/em>, August 11, 2022. Accessed February 24, 2023. https:\/\/www.nytimes.com\/2022\/08\/11\/science\/kamoya-kimeu-dead.html\/.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Stoneking, Mark. 2015. \u201cOf Lice and Men: The Molecular Evolution of Human Lice.\u201d Lecture, Center for Academic Research &amp; Training in Anthropogeny, San Diego, California, October 16, 2015. Accessed February 24, 2023. <a class=\"rId111\" style=\"color: #000000\" href=\"https:\/\/carta.anthropogeny.org\/events\/unique-features-human-skin\" target=\"_blank\">https:\/\/carta.anthropogeny.org\/events\/unique-features-human-skin<\/a>.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\">Tarlach, Gemma. 2015. \u201cThe First Humans to Know Winter.\u201d <em>Discover<\/em>, February 26. https:\/\/www.discovermagazine.com\/planet-earth\/the-first-humans-to-know-winter<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Ungar, Peter S. 2017. <em>Evolution's Bite: A Story of Teeth, Diet, and Human Origins<\/em>. Princeton, NJ: Princeton University Press.<strong><br style=\"clear: both\" \/><\/strong><\/span><\/p>\n<h2 class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\">References<\/span><\/h2>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\">Aiello, Leslie C., and Peter Wheeler. 1995. \u201cThe Expensive-Tissue Hypothesis.\u201d <em>Current Anthropology<\/em> 36 (2): 199\u2013221.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\">Anton, Susan C., Richard Potts, and Leslie C. Aiello. 2014. \u201cEvolution of Early <em>Homo<\/em>: An Integrated Biological Perspective.\u201d <em>Science<\/em> 345 (6192) doi: 10.1126\/science.1236828.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\">Anton, Susan C., and J. Josh Snodgrass. 2012. \u201cOrigins and Evolution of Genus <em>Homo<\/em>: New Perspectives.\u201d <em>Current Anthropology<\/em> 53 (S6): S479\u2013S496.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\">Ashton, Nick, Simon G. Lewis, Isabelle De Groote, Sarah M. Duffy, Martin Bates, Richard Bates, Peter Hoare, et al. 2014. \u201cHominin Footprints from Early Pleistocene Deposits at Happisburgh, UK.\u201d <em>PLOS ONE<\/em> 9 (2): e88329.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\">Belmaker, Miriam. 2010. \u201cEarly Pleistocene Faunal Connections between Africa and Eurasia: An Ecological Perspective.\u201d In <em>Out of Africa I: The First Hominin Colonization of Eurasia<\/em>, edited by John G. Fleagle, John J. Shea, Frederick E. Grine, Andrea L. Baden, and Richard E. Leakey, 183\u2013205. Dordrecht: Springer Netherlands.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Blumenschine, Robert, Henry T. Bunn, Valerius Geist, Fumiko Ikawa-Smith, Curtis W. Marean, Anthony G. Payne, John Tooby, J. 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Dordrecht: Springer Netherlands.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\">deMenocal, Peter B. 2014. \u201cClimate Shocks.\u201d <em>Scientific American<\/em> 311 (3): 48\u201353.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\">Dennell, Robin, and Wil Roebroeks. 2005. \u201cAn Asian Perspective on Early Human Dispersal from Africa.\u201d <em>Nature<\/em> 438 (7071): 1099\u20131104.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\">Hawkes, Kristen, James F. O\u2019Connell, Nicholas G. Blurton Jones, Helen Alvarez, and Eric L. 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Edwards, et al. 2020. \"Contemporaneity of <em>Australopithecus<\/em>, <em>Paranthropus<\/em>, and early <em>Homo erectus<\/em> in South Africa.\" <em>Science<\/em> 368 (6486). https:\/\/doi.org\/10.1126\/science.aaw7293<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\">Hill, Kim, and Hillard Kaplan. 1999. \u201cLife History Traits in Humans: Theory and Empirical Studies.\u201d <em>Annual Review of Anthropology<\/em> 28: 397\u2013430.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\">Hlubik, Sarah, Francesco Berna, Craig Feibel, David Braun, and John W. K. 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New York: Basic Books.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\">Zhu, Zhaoyu, Robin Dennell, Weiwen Huang, Yi Wu, Shifan Qiu, Shixia Yang, and Zhiguo Rao. 2018. \u201cHominin Occupation of the Chinese Loess Plateau Since about 2.1 Million Years Ago.\u201d <em>Nature<\/em> 559: 608\u2013612.<\/span><\/p>\n<h2 class=\"import-Normal\"><span style=\"color: #000000\">Acknowledgements<br \/>\n<\/span><\/h2>\n<p class=\"import-Normal\"><span style=\"color: #000000\">The author gratefully acknowledges funding from the California Community Colleges Chancellor\u2019s Office Zero Textbook Cost Degree Grant Program\u2014Implementation Phase 2.<\/span><\/p>\n<\/div>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1695_1874\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1695_1874\"><div tabindex=\"-1\"><div class=\"__UNKNOWN__\">\n<p class=\"import-Normal\">Amanda Wolcott Paskey, M.A., Cosumnes River College<\/p>\n<p class=\"import-Normal\">AnnMarie Beasley Cisneros, M.A., American River College<\/p>\n<h6>Student contributors to this chapter: Peyton Dagg, Bryana Henry, and Anoriel Jacques<\/h6>\n<p class=\"import-Normal\"><em>This chapter is a revision from \"<\/em><a class=\"rId7\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-16\/\"><em>Chapter 11: Archaic Homo<\/em><\/a><em>\u201d by Amanda Wolcott Paskey and AnnMarie Beasley Cisneros. In <\/em><a class=\"rId8\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\"><em>Explorations: An Open Invitation to Biological Anthropology, first edition<\/em><\/a><em>, edited by Beth Shook, Katie Nelson, Kelsie Aguilera, and Lara Braff, which is licensed under <\/em><a class=\"rId9\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\" target=\"_blank\"><em>CC BY-NC 4.0<\/em><\/a><em>. <\/em><\/p>\n<div class=\"textbox textbox--learning-objectives\">\n<header class=\"textbox__header\">\n<h2 class=\"textbox__title\">Learning Objectives<\/h2>\n<\/header>\n<div class=\"textbox__content\">\n<ul>\n<li class=\"import-Normal\">Identify the main groupings of Archaic <em>Homo sapiens<\/em>, such as Neanderthals.<\/li>\n<li class=\"import-Normal\">Explain how shifting environmental conditions required flexibility of adaptations, both anatomically and behaviourally.<\/li>\n<li class=\"import-Normal\">Describe the unique anatomical and cultural characteristics of Archaic <em>Homo sapiens, <\/em>including Neanderthals, in contrast to other hominins.<\/li>\n<li class=\"import-Normal\">Articulate how Middle Pleistocene hominin fossils fit into evolutionary trends including cranial capacity (brain size) development, cultural innovations, and migration patterns.<\/li>\n<li class=\"import-Normal\">Identify the shared traits, regional variations, and local adaptations among Archaic <em>Homo sapiens.<\/em><\/li>\n<li class=\"import-Normal\">Detail the increased complexity and debates surrounding the classification of hominins in light of transitional species, species admixture, etc.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<h2 class=\"import-Normal\">Breaking the Stigma of the \"Caveman\"<\/h2>\n<p class=\"import-Normal\">What do you think of when you hear the word \u201ccaveman\u201d? Perhaps you imagine a character from a film such as <em>The Croods<\/em>, <em>Tarzan<\/em>, and <em>Encino Man<\/em> or from the cartoon <em>The Flintstones<\/em>. Maybe you picture the tennis-playing, therapy-going hairy Neanderthals from Geico Insurance commercials. Or perhaps you imagine characters from <em>The Far Side<\/em> or <em>B.C.<\/em> comics. Whichever you picture, the character in your mind is likely stooped over with a heavy brow, tangled long locks and other body hair, and clothed in animal skins, if anything. They might be holding a club with a confused look on their face, standing at the entrance to a cave or dragging an animal carcass to a fire for their next meal (see Figure 12.1). You might have even signed up to take this course because of what you knew\u2014or expected to learn\u2014about \u201ccavemen.\u201d<\/p>\n<figure style=\"width: 163px\" class=\"wp-caption alignleft\"><img src=\"https:\/\/cdn.pixabay.com\/photo\/2013\/07\/13\/12\/36\/caveman-159964_1280.png\" alt=\"Free caveman beard man vector\" width=\"163\" height=\"317\" \/><figcaption class=\"wp-caption-text\">Figure 12.1:\u00a0Cartoon illustration of a prehistoric \u201ccaveman\u201d, commonly used as a visual representation of early humans in the Stone Age. Credit: <em data-start=\"261\" data-end=\"293\">Caveman, Beard, Man, Primitive<\/em>\u00a0free to use under the Pixabay <a href=\"https:\/\/pixabay.com\/service\/license-summary\/\" target=\"_blank\">Content License.<\/a><\/figcaption><\/figure>\n<p class=\"import-Normal\">These images have long been the stigma and expectation about our ancestors at the transition to modern <em>Homo sapiens<\/em>. Tracing back to works as early as Carl Linnaeus, scientists once propagated and advanced this imagery, creating a clear picture in the minds of early scholars that informed the general public, even through today, that Archaic <em>Homo sapiens<\/em>, \u201ccavemen,\u201d were somehow fundamentally different and much less intelligent than we are now. Unfortunately, this view is overly simplistic, misleading, and incorrect. Understanding what Archaic <em>Homo sapiens<\/em> were actually like requires a much more complex and nuanced picture, one that comes into sharper focus as continuing research uncovers more about the lives of our not-too-distant (and not-too-different) ancestors.<\/p>\n<p class=\"import-Normal\">The first characterizations of Archaic <em>Homo sapiens<\/em> were formed from limited fossil evidence in a time when <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1582\">ethnocentric<\/a><\/strong> and species-centric perspectives (<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1583\">anthropocentrism<\/a><\/strong>) were more widely accepted and entrenched in both society and science. Today, scientists are working from a more complete fossil record from three continents (Africa, Asia, and Europe), and genetic evidence informs their analyses and conclusions. The existence of Archaic <em>Homo sapiens<\/em> marks an exciting point in our lineage\u2014a point at which many modern traits had emerged and key refinements were on the horizon. Anatomically, humans today are not that much different from Archaic <em>Homo sapiens<\/em>.<\/p>\n<h2><\/h2>\n<h2 class=\"import-Normal\">The Changing Environment<\/h2>\n<p class=\"import-Normal\">While modern climate change is of critical concern today due to its cause (human activity) and pace (unprecedentedly rapid), the existence of global climate change itself is not a recent phenomenon. The focus of this chapter, the Middle Pleistocene (roughly between 780 kya and 125 kya), is the time period in which Archaic <em>Homo sapiens <\/em>appears in the fossil record\u2014a time that witnessed some of the most drastic climatic changes in human existence. During this time period, there were 15 major and 50 minor glacial events in Europe, alone.<\/p>\n<p class=\"import-Normal\">What exactly is <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1635\">glaciation<\/a><\/strong>? When scientists talk about glacial events, they are referring to the climate being in an ice age. This means that the ocean levels were much lower than today, because much of the earth\u2019s water was tied up in large glaciers or ice sheets. Additionally, the average temperature would have been much cooler, which would have better supported an Arctic or tundra-adapted plant-and-animal ecosystem in northern latitudes. The most interesting and relevant features of Middle Pleistocene glacial events are the sheer number of them and their repeated bouts: this era alternated between glacial periods and warmer periods, known as<strong> interglacials<\/strong>. In other words, the planet wasn\u2019t in an ice age the whole time.<\/p>\n<p class=\"import-Normal\">You can see the dramatic and increasing fluctuations in temperature, recorded through <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_906\">foraminifera<\/a><\/strong>, in Figure 12.2. The distance between highs and lows demonstrates the severity of temperature shifts. Much as the Richter scale represents more intense earthquakes with more dramatic peaks, so too does this chart, which uses dramatic peaks to demonstrate intense temperature swings.<\/p>\n<figure id=\"attachment_346\" aria-describedby=\"caption-attachment-346\" style=\"width: 1753px\" class=\"wp-caption alignnone\"><img class=\"size-full wp-image-329\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/All_palaeotemps.png\" alt=\"The graph shows changes in Earth\u2019s temperature for the last 540 My.\" width=\"1753\" height=\"565\" \/><figcaption id=\"caption-attachment-346\" class=\"wp-caption-text\">Figure 12.2: The Geologic Timescale and corresponding temperature shifts. Wide and rapid shifts took place during the Pleistocene (the second box from the right). More dramatic fluctuations depict greater severity of temperature shift. The Eocene, Pliocene, and Holocene epochs had more stable temperatures. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:All_palaeotemps.png\" target=\"_blank\">All paleotemps<\/a> by Glen Fergus is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Glacial periods are defined by Earth\u2019s average temperature being lower. Worldwide, temperatures are reduced, with cold areas becoming even colder. Huge portions of the landscape may have become inaccessible during glacial events due to the formation of glaciers and massive ice sheets. In Europe, the Scandinavian continental glacier covered what is today Ireland, England, Sweden, Norway, Denmark, and some of continental Europe. Plant and animal communities shifted to lower latitudes along the periphery of ice sheets. Additionally, some new land was opened during glacials. Evaporation with little runoff reduced sea levels by as much as almost 150 metres, shifting coastlines outward by in some instances as much as almost 100 kilometres. Additionally, land became exposed that connected what were previously unconnected continents such as Africa into Yemen at the Gulf of Aden.<\/p>\n<p class=\"import-Normal\">Glacial periods also affected equatorial regions and other regions that are today thought of as warmer or at least more temperate parts of the globe, including Africa. While these areas were not covered with glaciers, increased global glaciation resulted in lower sea levels and expanded coastlines. Cooler temperatures were accompanied by the drying of the climate, which caused significantly reduced rainfall, increased aridity, and the expansion of deserts. It is an interesting question to consider whether the same plants and animals that lived in these regions prior to the ice ages would be able to survive and thrive in this new climate. Plant and animal communities shifted in response to the changing climate, whenever possible.<\/p>\n<h2 class=\"import-Normal\">Surviving During the Middle Pleistocene<\/h2>\n<p class=\"import-Normal\">Rather than a single selective force, the Middle Pleistocene was marked by periods of fluctuation, not just cold periods. Interglacials interrupted glaciations, reversing trends in sea level, coastline, temperature, precipitation, and aridity, as well as glacier size and location. Interglacials are marked by increased rainfall and a higher temperature, which causes built-up ice in glaciers to melt. This leads to glacial retreat, which is the shrinking of glaciers and the movement of the glaciers back toward the poles, as we\u2019ve seen in our lifetime. During interglacials, sea levels increase, flooding some previously exposed coastlines and continental connections. In addition, plant and animal communities shift accordingly, often finding more temperate climates to the north and less arid and more humid climates in the tropics (Van Andel and Tzedakis 1996).<\/p>\n<p class=\"import-Normal\">Scientists have found that the Olorgesailie region in southern Kenya was at various times in the Middle Pleistocene a deep lake, a drought-dried lakebed with an area criss-crossed by small streams, and a grassland. While various animal species would have moved in and out of the area as the climate shifted, some animal species went extinct, and new, often related, species took up residence. The trend, scientists noted, was that animals with more specialized features went extinct and animals with more generalized features, such as animals we see today, survived in this changing climatic time period. For example, a zebra with specialized teeth for eating grass was ultimately replaced by a zebra that could eat both grass and other types of vegetation. If this small, localized example shows such a dramatic change in terms of the environment and the plant and animal biocommunities, what would have been the impact on humans?<\/p>\n<p class=\"import-Normal\">There is no way humans could have escaped the effects of Middle Pleistocene climate change, no matter what region of the world they were living in. As noted earlier, and as evidenced by what was seen in the other biotic communities, humans would have faced changing food sources as previous sources of food may have gone extinct or moved to a different latitude. Depending on where they were living, fresh water may have been limited. Durial glacials, lower sea levels would have given humans more land to live on, while the interglacials would have reduced the available land through the increase in rainfall and associated sea level rise. Dry land connections between the continents would have made movement from one continent to another by foot easier at times than today, although these passageways were not consistently available through the Middle Pleistocene due to the glacial\/interglacial cycle. Finally, as evidenced by the Olorgesailie region in Kenya, during the Middle Pleistocene animal species that were overly specialized to one particular type of environment were less likely to survive when compared to their more generalized counterparts. Evidence suggests that this same pattern may have held true for Archaic <em>Homo sapiens<\/em>, in terms of their ability to survive this dramatic period of climate change.<\/p>\n<h2 class=\"import-Normal\">Defining Characteristics of Archaic <em>Homo sapiens<\/em><\/h2>\n<p class=\"import-Normal\">Archaic <em>Homo sapiens<\/em> share our species name but are distinguished by the term \u201cArchaic\u201d as a way of recognizing both the long period of time between their appearance and ours, as well as the way in which human traits have continued to evolve over time\u2014making Archaic <em>Homo sapiens <\/em>look slightly different from us today, despite being considered the same species. Living throughout Africa, and the Middle East during the Middle Pleistocene, Archaic <em>Homo sapiens <\/em>are considered, in many ways, transitional between <em>Homo <\/em><em>erectus<\/em> and modern <em>Homo sapiens <\/em>(see Figure 12.3). Archaic<em> Homo sapiens<\/em> share the defining trait of an increased brain size of at least 1,100 cc and averaging 1,200 cc, although there are significant regional and temporal (time) variations. Because of these variations, scientists disagree on whether these fossils represent a single, variable species or multiple, closely related species (sometimes called <em>Homo antecessor<\/em>,<em> Homo bodoensis, Homo heidelbergensis<\/em>,<em> Homo georgicus<\/em>,<em> Homo neanderthalensis<\/em>, and <em>Homo rhodesiensis<\/em>).<\/p>\n<p class=\"import-Normal\">An active area of scholarship in the discipline involves reconciling the diversity of species from this time period and establishing the phylogenetic relationships between them. The term \u201cArchaic <em>Homo sapiens\u201d <\/em>can mean different things to different scholars within the discipline. The intent of this chapter is to provide an understanding of the diversity of this time period and provide data used to make interpretations from among the most likely possibilities. Although we recognize that some anthropologists split many of these fossils into separate species, until the issue is resolved at the discipline level, this chapter will rely on the widely used naming conventions that refer to many fossils from this time period as Archaic <em>Homo sapiens<\/em>. We will discuss these contemporaneous fossils as a unit<em>, <\/em>with the exception of a particularly unique population living in Europe and West Asia known as the Neanderthals, which we will examine separately.<\/p>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<caption>Figure 12.3: A comparison of Homo erectus, Archaic Homo sapiens, and anatomically modern Homo sapiens. This table compares key traits of the crania and postcrania that distinguish these three hominins. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-16\/\" target=\"_blank\">Homo erectus, Archaic Homo sapiens, and anatomically modern Homo sapiens table (Figure 11.3)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Amanda Wolcott Paskey and AnnMarie Beasley Cisneros is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/caption>\n<thead>\n<tr style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Trait<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong><em>Homo <\/em><\/strong><strong><em>erectus<\/em><\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Archaic <\/strong><strong><em>Homo sapiens <\/em><\/strong><strong>(including Neaderthals)<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Anatomically Modern <\/strong><strong><em>Homo sapiens<\/em><\/strong><\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Time<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1.8 mya\u2013200,000 ya<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">600,000\u201340,000 ya<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">315,000 ya\u2013today<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Brain size<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">900 cc<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1,200 cc (1,500 cc when including Neanderthals)<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1,400 cc<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Skull Shape<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Long and low,<\/p>\n<p class=\"import-Normal\">angular<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Intermediate<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Short and high, <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1643\">globular<\/a><\/strong><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Forehead<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Absent<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Emerging<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Present<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Nasal Region<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Projecting nasal bones (bridge of the nose), no midfacial prognathism<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Wider nasal aperture and some midfacial prognathism, particularly pronounced among Neanderthals<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Narrower nasal aperture, no midfacial prognathism<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Chin<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Absent<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Absent<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Present<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Other Facial Features<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Large brow ridge and large projecting face<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Intermediate<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Small brow ridge and<strong> retracted face<\/strong><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Other Skull Features<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Nuchal torus, sagittal keel, thick cranial bone<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Projecting occipital bone, often called occipital bun in Neanderthals; intermediate thickness of cranial bone<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Small bump on rear of skull, if anything; thin cranial bone<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dentition<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Large teeth, especially front teeth<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Slightly smaller teeth; front teeth still large;<\/p>\n<p class=\"import-Normal\">retromolar gap in Neanderthals<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Smaller teeth<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Postcranial Features<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Robust bones of skeleton<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Robust bones of skeleton<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">More gracile bones of skeleton<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<p class=\"import-Normal\">When comparing <em>Homo <\/em><em>erectus<\/em>, Archaic<em> Homo sapiens, <\/em>and anatomically modern <em>Homo sapiens<\/em>, one can see that Archaic<em> Homo sapiens<\/em> are intermediate in their physical form. For some features, this follows the trends first seen in <em>Homo <\/em><em>erectus<\/em> with other features having early, less developed forms of traits seen in modern <em>Homo sapiens<\/em>. For example, Archaic <em>Homo sapiens<\/em> trended toward less angular and higher skulls than <em>Homo <\/em><em>erectus<\/em><em>. <\/em>However, the archaic skulls were not as short and globular and had less developed foreheads compared to anatomically modern <em>Homo sapiens. <\/em>Archaic <em>Homo sapiens<\/em> had smaller brow ridges and a less-projecting face than <em>Homo <\/em><em>erectus<\/em> and slightly smaller teeth, although incisors and canines were often about as large as those of <em>Homo <\/em><em>erectus<\/em>. Archaic <em>Homo sapiens <\/em>also had a wider <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1638\">nasal aperture<\/a><\/strong>, or opening for the nose, and a forward-projecting midfacial region, which is later seen more fully developed among Neanderthals and is known as <strong>midfacial prognathism<\/strong>. The occipital bone often projected and the cranial bone was of intermediate thickness, somewhat reduced from <em>Homo <\/em><em>erectus<\/em> but not nearly as thin as that of anatomically modern <em>Homo sapiens. <\/em>The postcrania remained fairly robust. Identifying a set of features that is unique to Archaic<em> Homo sapiens<\/em> is a challenging task, due to both individual and geographic variation\u2014these developments were not all present to the same degree in all individuals. Neanderthals are the exception, as they had several unique traits that made them notably different from modern <em>Homo sapiens<\/em> as well as their closely related Archaic cousins.<\/p>\n<figure style=\"width: 299px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image10-4.png\" alt=\"Archaic Homo sapiens skull cast.\" width=\"299\" height=\"299\" \/><figcaption class=\"wp-caption-text\">Figure 12.4: \u201cBroken Hill Man,\u201d found at Kabwe in Zambia, shows common traits associated with archaic Homo sapiens in Africa, including a large brain, taller cranium, and Homo erectus-like features such as massive brow ridges, a large face, and thick cranial bones. Credit: <a href=\"https:\/\/boneclones.com\/product\/homo-heidelbergensis-skull-broken-hill-1-rhodesian-man-BH-004\" target=\"_blank\">Homo heidelbergensis Cranium Broken Hill 1 (Rhodesian Man)<\/a> by <a href=\"https:\/\/boneclones.com\/\" target=\"_blank\">\u00a9BoneClones<\/a> is used by permission and available here under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">The one thing that is clear about Archaic <em>Homo sapiens<\/em> is that, despite general features, there is a lot of regional variation, which is first seen in the different <em>Homo <\/em><em>erectus<\/em> specimens across Asia and Africa. While the general features of Archaic <em>Homo sapiens<\/em>, identified earlier, are present in the fossils of this time period, there are significant regional differences. The majority of this regional variation lies in the degree to which fossils have features more closely aligned with <em>Homo <\/em><em>erectus<\/em> or with anatomically modern <em>Homo sapiens<\/em>.<\/p>\n<figure style=\"width: 244px\" class=\"wp-caption alignright\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image7-5.png\" alt=\"Side view of the Dali cranium.\" width=\"244\" height=\"213\" \/><figcaption class=\"wp-caption-text\">Figure 12.5: Dali cranium, found at Dali, China, is representative of traits seen in archaic Homo sapiens in Asia, including large and robust features with heavy brow ridges like Homo erectus and a large cranial capacity intermediate between Homo erectus and anatomically modern Homo sapiens. Credit: Dali skull original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by <a href=\"https:\/\/marynelsonstudio.com\" target=\"_blank\">Mary Nelson<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p>To illustrate this point, we will examine three exemplary specimens, one from each of the three continents on which Archaic<em> Homo sapiens <\/em>lived. First, in Africa, a specimen from Broken Hill is one of several individuals found in the Kabwe lead mine in Zambia. It had a large brain (1,300 cc) and taller cranium as well as many <em>Homo erectus-<\/em>like skull features, including massive brow ridges, a large face, and thick cranial bones (Figure 12.4). Second, one partial crania from Dali, China, is representative of Archaic<em> Homo sapiens <\/em>in Asia, with large and robust features with heavy brow ridges, akin to what is seen in <em>Homo <\/em><em>erectus<\/em>, and a large cranial capacity intermediate between <em>Homo <\/em><em>erectus<\/em> and anatomically modern <em>Homo sapiens<\/em> (Figure 12.5). Third, an almost-complete skeleton was found in northern Spain at Atapuerca. Atapuerca 5 (Figure 12.6) has thick cranial bone, an enlarged cranial capacity, intermediate cranial height, and a more rounded cranium than seen previously. Additionally, Atapuerca 5 demonstrates features that foreshadow Neanderthals, including increased midfacial prognathism. After examining some of the fossils such as those from Kabwe, Dali, and Atapuerca, the transitional nature of Archaic<em> Homo sapiens <\/em>is clear: their features place them squarely between <em>Homo <\/em><em>erectus<\/em> and modern <em>Homo sapiens<\/em>.<\/p>\n<figure style=\"width: 293px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image13-4.png\" alt=\"Archaic Homo sapiens skull cast with mandible.\" width=\"293\" height=\"293\" \/><figcaption class=\"wp-caption-text\">Figure 12.6: Atapuerca 5 archaic Homo sapiens, found in northern Spain, is representative of traits seen in archaic Homo sapiens in Europe, including a thick cranial bone, an enlarged cranial capacity, intermediate cranial height, a more rounded cranium, and increased midfacial projection. Credit: <a href=\"https:\/\/boneclones.com\/product\/homo-heidelbergensis-skull-atapuerca-5-BH-022\" target=\"_blank\">Homo heidelbergensis Skull Atapuerca 5<\/a> by <a href=\"https:\/\/boneclones.com\/\" target=\"_blank\">\u00a9BoneClones<\/a> is used by permission and available here under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Due to the transitional nature of Archaic<em> Homo sapiens<\/em>, identifying the time period with which they are associated is problematic and complex. Generally, it is agreed that Archaic<em> Homo sapiens <\/em>lived between 600,000 and 200,000 years ago, with regional variation and overlap between <em>Homo <\/em><em>erectus<\/em> on the early end of the spectrum and modern <em>Homo sapiens <\/em>and Neanderthals on the latter end. The earliest-known Archaic<em> Homo sapiens <\/em>fossils tentatively date to about 600,000 years ago in Africa, to around 300,000 years ago in Asia, and to about 350,000 years ago in Europe (and potentially as early as 600,000 years ago). Determining the end point of Archaic<em> Homo sapiens <\/em>is also problematic since it largely depends upon when the next subspecies of <em>Homo sapiens <\/em>appears and the classification of highly intermediate specimens. For example, in Africa, the end of Archaic<em> Homo sapiens <\/em>is met with the appearance of modern <em>Homo sapiens<\/em>, while in Europe it is the appearance of Neanderthals that is traditionally seen as marking the transition from other Archaic<em> Homo sapiens. <\/em><\/p>\n<p class=\"import-Normal\">It is important to remember that this time period is represented by many branching relationships and assuming an evolutionary trajectory that follows a single linear path would not be correct. Even still, Archaic<em> Homo sapiens <\/em>mark an important chapter in the human lineage, connecting more ancestral forms, such as <em>Homo <\/em><em>erectus<\/em>, to modern <em>Homo sapiens<\/em>. During this period of climatic transition and fluctuation, Archaic <em>Homo sapiens<\/em> mirror the challenges of their environments. Showing increasing regional variation due to the need for local adaptation, there is no single archetype for this group; the defining characteristic seems to be variability.<\/p>\n<h2 class=\"import-Normal\">Neanderthals<\/h2>\n<p class=\"import-Normal\">One well-known population of Archaic <em>Homo sapiens <\/em>are the Neanderthals, named after the site where they were first discovered in the Neander Valley, or \u201cthal\u201d in German, located near Dusseldorf, Germany. Popularly known as the stereotypical \u201ccavemen\u201d examined at the outset of this chapter, recent research is upending long-held beliefs about this group of Archaics. Neanderthal behaviour was increasingly complex, far beyond what was exhibited by even other Archaic <em>Homo sapiens<\/em> discussed throughout this chapter. We implore you to forget the image of the iconic caveman and have an open mind when exploring the fossil evidence of the Neanderthals.<\/p>\n<p class=\"import-Normal\">It is important to understand why Neanderthals are separated from other Archaic <em>Homo sapiens<\/em>. Unlike the rest of Archaic <em>Homo sapiens<\/em>, Neanderthals are easily defined and identified in many ways. Evidence suggests the time period when Neanderthals lived was between 150,000 and 40,000 years ago. There is a clear geographic boundary of where Neanderthals lived: western Europe, the Middle East, and western Asia. No Neanderthal fossils have ever been discovered outside of this area, including Africa. This is a bit curious, as other Archaics seem to have adapted in Africa and then migrated elsewhere, but Neanderthals\u2019 regional association makes sense in light of the environment to which they were best adapted: namely, extreme cold weather. Additionally, Neanderthals have a unique and distinct cluster of physical characteristics. While a few aspects of Neanderthals are shared among some Archaic <em>Homo sapiens<\/em>, such as the types of tools, most Neanderthal anatomical and behavioural attributes are unique to them.<\/p>\n<p class=\"import-Normal\">Neanderthals lived during some of the coldest times during the last Ice Age and at far northern latitudes. This means Neanderthals were living very close to the glacial edge, rather than in a more temperate region of the globe like some of their Archaic <em>Homo sapiens<\/em> relatives. While able to survive in arctic conditions, most Neanderthal sites dating to the glacial periods were found farther away from the severe cold, in a steppe tundra-like environment, which would have been more hospitable to Neanderthals, and their food sources, both flora and fauna (Ashton 2002; Nicholson 2017; Richter 2006). Their range likely expanded and contracted along with European glacial events, moving into the Middle East during glacial events when Europe became even cooler, and when the animals they hunted would have moved for the same reason. During interglacials, when Europe warmed a bit, Neanderthals and their prey would have been able to move back into Western Europe. Clearly, the true hallmark of Neanderthals is their adaptation to an unstable environment, shifting between warm and cold, as the climate was in constant flux throughout their existence (Adler Et al. 2003; Boettger Et al. 2009).<\/p>\n<p class=\"import-Normal\">Many of the Neanderthals\u2019 defining physical features are more extreme and robust versions of traits seen in other Archaic<em> Homo sapiens<\/em>, clustered in this single population. Brain size, namely an enlargement of the cranial capacity, is one such trait. The average Neanderthal brain size is around 1,500 cc, and the range for Neanderthal brains can extend to upwards of 1,700 cc. The majority of the increase in the brain occurs in the occipital region, or the back part of the brain, resulting in a skull that has a large cranial capacity with a distinctly long and low shape that is slightly wider than previous forms at the far back of the skull. Modern humans have a brain size comparable to that of Neanderthals; however, our brain expansion occurred in the frontal region of the brain, not the back, as in Neanderthal brains. This difference is also the main reason why Neanderthals lack the vertical forehead that modern humans possess. They simply did not need an enlarged forehead, because their brain expansion occurred in the rear of their brain. Due to cranial expansion, the back of the Neanderthal skull is less angular (as compared to <em>Homo erectus<\/em>), but not as rounded as <em>Homo sapiens<\/em>, producing an elongated shape, akin to a football.<\/p>\n<p class=\"import-Normal\">Another feature that continues the trend noted in previous hominins is the enlargement of the nasal region, or the nose. Neanderthal noses are large and have a wide nasal aperture, which is the opening for the nose. While the nose is only made up of two bones, the nasals, the true size of the nose can be determined by looking at other facial features, including the nasal aperture, and the angle of the nasal and maxillary, or facial bones. In Neanderthals, these indicate a large, forward-projecting nose that appears to be pulled forward away from the rest of the face. This feature is further emphasized by the backward-sloping nature of the cheekbones, or the zygomatic arches. The unique shape and size of the Neanderthal nose is often characterized by the term <em>midfacial prognathism<\/em>\u2014a jutting out of the middle portion of the face, or nose. This is in sharp contrast to the prognathism exhibited by other hominins, who exhibited prognathism, or the jutting out, of their jaws.<\/p>\n<p class=\"import-Normal\">The teeth of the Neanderthals follow a similar pattern seen in the Archaic <em>Homo sapiens<\/em>, which is an overall reduction in size, especially as compared to the extremely large teeth seen in the genus <em>Australopithecus<\/em>. However, while the teeth continued to reduce, the jaw size did not keep pace, leaving Neanderthals with an oversized jaw for their teeth, and a gap between their final molar and the end of their jaw. This gap is called a <strong>retromolar gap<\/strong>.<\/p>\n<p class=\"import-Normal\">The projecting occipital bone present in other Archaic<em> Homo sapiens <\/em>is also more prominent in Neanderthals, extending the trend found in Archaics. Among Neanderthals, this projection of bone is easily identified by its bun shape on the back of the skull and is known as an <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1645\">occipital bun<\/a><\/strong>. This projection appears quite similar to a dinner roll in size and shape. Its purpose, if any, remains unknown.<\/p>\n<p class=\"import-Normal\">Continuing the Archaic<em> Homo sapiens <\/em>trend, Neanderthal brow ridges are prominent but somewhat smaller in size than those of <em>Homo <\/em><em>erectus<\/em> and earlier Archaic<em> Homo sapiens. <\/em>In Neanderthals, the brow ridges are also often slightly less arched than those of other Archaic<em> Homo sapiens<\/em>.<\/p>\n<p class=\"import-Normal\">In addition to extending traits present in Archaic<em> Homo sapiens, <\/em>Neanderthals possess several distinct traits. Neanderthal <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1646\">infraorbital foramina<\/a><\/strong>, the holes in the maxillae or cheek bones through which blood vessels pass, are notably enlarged compared to other hominins. The Neanderthal postcrania are also unique in that they demonstrate increased robusticity in terms of the thickness of bones and body proportions that show a barrel-shaped chest and short, stocky limbs, as well as increased musculature. These body portions are seen across the spectrum of Neanderthals\u2014in men, women, and children.<\/p>\n<p class=\"import-Normal\">Traditionally, many of the unique traits that Neanderthals possess were seen as adaptations to the extreme cold, dry environments in which they often lived and which exerted strong selective forces. For example, Bergmann\u2019s and Allen\u2019s Rules dictate that an increased body mass and short, stocky limbs are common in animals that live in cold conditions. Neanderthals were said to have matched the predictions of Bergmann\u2019s and Allen\u2019s Rules perfectly (Churchill 2006). In addition, the Neanderthal skull also exhibits adaptations to the cold. Neanderthals\u2019 large infraorbital foramina allow for larger blood vessels, increasing the volume of blood that is found closest to the skin, which helps to keep the skin warmer. Their enlarged noses resulted in longer nasal passages and mucus membranes that warmed and moistened cold air before it reached the lungs. The Neanderthals\u2019 larger nose has long been thought to have acted as a humidifier, easing physical exertion in their climate, although research on this particular trait continues to be studied and debated (Rae Et al. 2011).<\/p>\n<p class=\"import-Normal\">New research, however, seems to suggest that these unique skeletal adaptations might not have been strict adaptations to cold weather (Evteev Et al. 2017; Pearce Et al. 2013). For example, large brow ridges might have served as a way to shade the face from the sun. The increased occipital portion of the brain, some researchers state, was to support a larger visual system present in Neanderthals. This visual system would have given them increased light sensitivity, which would have been useful in higher latitudes that had dark winters. And, while recent modeling of nostril airflow on reconstructed Neanderthal specimens supports the notion that Neanderthals had extensive mucus membranes inside their noses, the data shows that modern <em>Homo sapiens<\/em> are superior to Neanderthals in our ability to use our noses as a way to warm and cool air. However, Neanderthals were able to snort air through their noses better than we can. Why is this important? When combined with the fact that Neanderthals tended to prefer a more temperate, tundra-like environment, and that other physical traits suggest that Neanderthals had huge bodies that needed massive amounts of calories to sustain them, the picture gets clearer. Massive amounts of energy would have been required to power a Neanderthal body, and anything that might have made them more calorically efficient would have been favoured. Efficient breathing, through larger noses into large lungs, meaning deeper breaths, would have been favoured. To further save energy expenditure, body sizes might have been sacrificed as well. These same types of adaptations are similar to ones seen in children today who are born in high altitudes, not cold climates. Figure 12.7 provides a summary of these unique features of the Neanderthal.<\/p>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<caption>Figure 12.7: Neanderthal distinguishing features. This table outlines key features associated with Neanderthals. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-16\/\" target=\"_blank\">Neanderthal distinguishing features table (Figure 11.6)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Amanda Wolcott Paskey and AnnMarie Beasley Cisneros is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/caption>\n<thead>\n<tr style=\"height: 21pt\">\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\" colspan=\"2\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Distinct Neanderthal Anatomical Features<\/strong><\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Brain Size<\/strong><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1,500 cc average<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Skull Shape<\/strong><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Long and low<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Brow Ridge Size<\/strong><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Large<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Nose Size<\/strong><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Large, with midfacial prognathism<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dentition<\/strong><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Reduced, but large jaw size, creating retromolar gap<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Occipital Region<\/strong><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Enlarged occipital region, occipital bun<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Other Unique Cranial Features<\/strong><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Large infraorbital foramina<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Postcranial Features<\/strong><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Short and stocky body, increased musculature, barrel-shaped chest<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<p class=\"import-Normal\">A classic example of a Neanderthal with all of the characteristics mentioned above is the nearly complete La Ferrassie 1 Neanderthal, from France. This is a male skeleton, with a brain size of around 1640cc, an extremely large nose and infraorbital foramina, brow ridges that are marked in size, and an overall robust skeleton (Figure 12.8).<\/p>\n<p>&nbsp;<\/p>\n<figure style=\"width: 390px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image1-4.png\" alt=\"A reproduction of a complete Neanderthal skeleton.\" width=\"390\" height=\"689\" \/><figcaption class=\"wp-caption-text\">Figure 12.8: La Ferrassie 1 Neanderthal is representative of many classic Neanderthal features, including a large brain, large nose, large infraorbital foramina, large brow ridges, and robust postcrania. Credit: <a href=\"https:\/\/boneclones.com\/product\/neanderthal-skeleton-articulated-SC-019-A\" target=\"_blank\">Neanderthal Skeleton Articulated<\/a> by <a href=\"https:\/\/boneclones.com\/\" target=\"_blank\">\u00a9BoneClones<\/a> is used by permission and available here under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<h3 class=\"import-Normal\"><strong>Neanderthal Culture: Tool Making and Use<\/strong><\/h3>\n<p class=\"import-Normal\">One key Neanderthal adaptation was their cultural innovations, which are an important way that hominins adapt to their environment. As you recall, <em>Homo erectus<\/em>'s tools, Acheulean handaxes, represented an increase in complexity over Oldowan tools, allowing more efficient removal of meat and possibly calculated scavenging. In contrast, Neanderthal tools mark a significant innovation in tool-making technique and use with <strong>Mousterian tools<\/strong> (named after the Le Moustier site in southwest France). These tools were significantly smaller, thinner, and lighter than Acheulean handaxes and formed a true toolkit. The materials used for Mousterian tools were of higher quality, which allowed for both more precise toolmaking and tool reworking when the tools broke or dulled after frequent reuse. The use of higher-quality materials is also indicative of required forethought and planning to acquire them for tool manufacture. It has been suggested that the Neanderthals, unlike <em>Homo <\/em><em>erectus<\/em>, saved and reused their tools, rather than making new ones each time a tool was needed.<\/p>\n<figure style=\"width: 290px\" class=\"wp-caption alignright\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image3-4.png\" alt=\"Large flakes separated from the core.\" width=\"290\" height=\"159\" \/><figcaption class=\"wp-caption-text\">Figure 12.9: The Levallois technique is used to create Mousterian tools. The multistep process involves preparing the core in a specific way to yield flakes that can be used as tools. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Nucl%C3%A9us_Levallois_La-Parrilla.png\" target=\"_blank\">Nucl\u00e9us Levallois La-Parrilla<\/a> by Jos\u00e9-Manuel Benito \u00c1lvarez is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.5\/legalcode\" target=\"_blank\">CC BY-SA 2.5 License<\/a>..<\/figcaption><\/figure>\n<p>Mousterian tools are constructed in a very unique manner, utilizing the <strong>Levallois technique<\/strong> (Figure 12.9), named after the first finds of tools made with this technique, which were discovered in the Levallois-Perret suburb of Paris, France. The Levallois technique is a multistep process that requires preparing the core, or raw material, in a specific way that will yield flakes that are roughly uniform in dimension. The flakes are then turned into individual tools. The preparation of the core is akin to peeling a potato or carrot with a vegetable peeler\u2014when peeling vegetables, you want to remove the skin in long, regular strokes, so that you are taking off the same amount of the vegetable all the way around. In the same way, the Levallois technique requires removing all edges of the <strong>cortex<\/strong>, or outside surface of the raw material, in a circle before removing the lid. The flakes, which will eventually be turned into the individual tools, can then be removed from the core. The potential yield of tools from one core would be many, as seen in Figure 12.10, compared to all previous tool-making processes, in which one core yielded a single tool. This manufacturing process might be considered the ultimate zero-waste tool-making technique (Delpiano Et al. 2018).<\/p>\n<figure style=\"width: 589px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image19-4.png\" alt=\"Levallois core and flakes that are gray in color and various shapes and sizes.\" width=\"589\" height=\"470\" \/><figcaption class=\"wp-caption-text\">Figure 12.10: Levallois core and flakes for tool production. Using this technique, one core is used to produce many flakes, each of which can be turned into a tool. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:NHM_-_Levalloiskern.jpg\" target=\"_blank\">NHM - Levalloiskern<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Xenophon\" target=\"_blank\">Wolfgang Sauber<\/a> (user: Xenophon) is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\" target=\"_blank\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">It is suggested that Neanderthal tools were used for a variety of purposes, including cutting, butchering, woodworking or antler working, and hide working. Additionally, because the Mousterian tools were lighter than previous stone tools, Neanderthals could <strong>haft<\/strong>, or attach the tool onto a handle, as the stone would not have been too heavy (Degano Et al. 2019). Neanderthals attached small stone blades onto short wood or antler handles to make knives or other small weapons, as well as attached larger blades onto longer shafts to make spears. New research examining tar-covered stones and black lumps at several Neanderthal sites in Europe suggests that Neanderthals may have been making tar by distilling it from birch tree bark, which could have been used to glue the stone tool onto its handle. If Neanderthals were, in fact, manufacturing tar to act as glue, this would predate modern humans in Africa using tree resin or similar adhesives by nearly 100,000 years.<\/p>\n<p class=\"import-Normal\">Evidence shows that raw materials used by Neanderthals came from distances as far away as 100 km. This could indicate a variety of things regarding Neanderthal behaviour, including a limited trade network with other Neanderthal groups or simply a large area scoured by Neanderthals when collecting raw materials. While research on specific applications continues, it should be clear from this brief discussion that Neanderthal tool manufacturing was much more complex than previous tool-making efforts, requiring technical expertise, patience, and skills beyond toolmaking to carry out.<\/p>\n<h3 class=\"import-Normal\"><strong>Neanderthal Culture: Hunting and Diet<\/strong><\/h3>\n<p class=\"import-Normal\">With their more sophisticated suite of tools and robust muscular bodies, Neanderthals were better armed for hunting than previous hominins. The animal remains in Neanderthal sites show that, unlike earlier Archaic <em>Homo sapiens<\/em>, Neanderthals were very effective hunters who were able to kill their own prey, rather than relying on scavenging. Though more refined than the tools of earlier hominins, the Neanderthal spear was not the kind of weapon that would have been thrown; rather, it would have been used in a jabbing fashion (Churchill 1998; Kortlandt 2002). This may have required Neanderthals to hunt in groups rather than individually and made it necessary to approach their prey quite closely (Gaudzinski-Windheuser Et al. 2018). Remember, the animals living with Neanderthals were very large-bodied due to their adaptations to cold weather; this would have included species of deer, horses, and bovids (relatives of the cow).<\/p>\n<p class=\"import-Normal\">Isotopes from Neanderthal bones show that meat was a significant component of their diet, similar to that seen in carnivores like wolves (Bocherens Et al. 1999; Jaouen Et al. 2019; Richards Et al. 2000). In addition to large prey, their diet included ibex, seals, rabbits, and pigeons. Though red meat was a critical component of the Neanderthal diet, evidence shows that at times they also ate limpets, mussels, and pine nuts. Tartar examined from Neanderthal teeth in Iraq and Belgium reveal that they also ate plant material including wheat, barley, date palms, and tubers, first cooking them to make them palatable (Henry Et al. 2010). While Neanderthals\u2019 diet varied according to the specific environment in which they lived, meat comprised up to 80% of their diet (Wi\u1e9ein Et al. 2015).<\/p>\n<h3 class=\"import-Normal\"><strong>Neanderthal Culture: Caring for the Injured and Sick<\/strong><\/h3>\n<p class=\"import-Normal\">While the close-range style of hunting used by Neanderthals was effective, it also had some major consequences. Many Neanderthal skeletons have been found with significant injuries, which could have caused paralysis or severely limited their mobility. Many of the injuries are to the head, neck, or upper body. Thomas Berger and Erik Trinkaus (1995) conducted a statistical comparative analysis of Neanderthal injuries compared to those recorded in modern-day workers\u2019 compensation reports and found that the closest match was between Neanderthal injuries and those of rodeo workers. Rodeo professionals have a high rate of head and neck injuries that are similar to the Neanderthals\u2019 injuries. What do Neanderthals and rodeo workers have in common? They were both getting very close to large, strong animals, and at times their encounters went awry.<\/p>\n<p class=\"import-Normal\">The extensive injuries sustained by Neanderthals are evident in many fossil remains. Shanidar 1 (Figure 12.11), an adult male found at the Shanidar site in northern Iraq and dating to 45,000 ya, has a lifetime of injuries recorded in his bones (Stewart 1977). Shanidar 1 sustained\u2014and healed from\u2014an injury to the face that would have likely caused blindness. His lower right arm was missing and the right humerus shows severe atrophy, likely due to disuse. This pattern has been interpreted to indicate a substantial injury that required or otherwise resulted in amputation or wasting away of the lower arm. Additionally, Shanidar 1 suffered from bony growths in the inner ear that would have significantly impaired his hearing and severe arthritis in the feet. He also exhibited extensive anterior tooth wear, matching the pattern of wear found among modern populations who use their teeth as a tool. Rather than an anomaly, the type of injuries evident in Shanidar 1 are similar to those found in many other Neanderthal fossils, revealing injuries likely sustained from hunting large mammals as well as demonstrating a long life of physical activity.<\/p>\n<p>&nbsp;<\/p>\n<p><img class=\"aligncenter\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image11-4.png\" alt=\"Neaderthal skull.\" width=\"329\" height=\"329\" \/><\/p>\n<figure style=\"width: 330px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image5-4.png\" alt=\"Neaderthal right and left humerus. The right humerus is withered looking.\" width=\"330\" height=\"330\" \/><figcaption class=\"wp-caption-text\">Figure 12.11a-b: a. The Shanidar 1 skull shows an injury to the face that would likely have caused blindness. b. The Shanidar 1 right humerus (on the left side of the image) shows severe atrophy, likely due to disuse. Credit: a. <a href=\"https:\/\/boneclones.com\/product\/shanidar-1-skull-BH-050\" target=\"_blank\">Homo neanderthalensis Shanidar 1 Skull<\/a> by <a href=\"https:\/\/boneclones.com\/\" target=\"_blank\">\u00a9BoneClones<\/a> is used by permission and available here under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>. b. <a href=\"https:\/\/humanorigins.si.edu\/evidence\/human-fossils\/fossils\/shanidar-1\" target=\"_blank\">Shanidar 1<\/a> by Chip Clark, <a href=\"https:\/\/www.si.edu\/\" target=\"_blank\">Smithsonian Institution<\/a> [exhibit: <a href=\"https:\/\/humanorigins.si.edu\/research\" target=\"_blank\">Human Evolution <\/a>Evidence, Human Fossils, Species, Homo neanderthalensis] <a href=\"https:\/\/www.si.edu\/termsofuse\" target=\"_blank\">is used for educational and non-commercial purposes as outlined by the Smithsonian.<\/a><\/figcaption><\/figure>\n<p class=\"import-Normal\">The pattern of injuries is as significant as the fact that Shanidar 1 and other injured Neanderthals show evidence of having <em>survived<\/em> their severe injuries. One of the earliest-known Neanderthal discoveries\u2014the one on whom misinformed analysis shaped the stereotype of the species for nearly a century\u2014is the La Chapelle-aux-Saints Neanderthal (Trinkaus 1985). The La Chapelle Neanderthal had a damaged eye orbit that likely caused blindness and suffered arthritis of the spine (Dawson and Trinkaus 1997). He had also lost most of his teeth, many of which he had lived without for so long that the mandibular and maxillary bones were partially reabsorbed due to lack of use. The La Chapelle Neanderthal was also thought to be at least in his mid-forties at death, an old age for the rough life of the Late Pleistocene\u2014giving rise to his nickname, \u201cthe Old Man.\u201d To have survived so long with so many injuries that obviously precluded successful large game hunting, he must have been taken care of by others. Such caretaking behaviour is also evident in the survival of other seriously injured Neanderthals, such as Shanidar 1. Long thought to be a hallmark modern human characteristic, taking care of the injured and elderly, for example preparing or pre-chewing food for those without teeth, indicates strong social ties among Neanderthals.<\/p>\n<h3 class=\"import-Normal\"><strong>Neanderthal Culture: Ritual Life<\/strong><\/h3>\n<p class=\"import-Normal\">Such care practices may have been expressed upon death as well. Nearly complete Neanderthal skeletons are not uncommon in the fossil record, and most are well preserved within apparently deliberate burials that involve deep graves and bodies found in specific, often fetal or <strong>flexed positions<\/strong> (Harrold 1980)<strong>.<\/strong> Discoveries of pollen in a grave at the Shanidar site in the 1960s led scientists to think that perhaps Neanderthals had placed flowering plants in the grave, an indication of ritual ceremony or spirituality so common in modern humans. But more recent investigations have raised some doubt about this conclusion (Pomeroy Et al. 2020). The pollen may have been brought in by burrowing rodents. Claims of <strong>grave goods<\/strong> or other ornamentation in burials are similarly debated, although possible.<\/p>\n<p class=\"import-Normal\">Some tantalizing evidence for symbolism, and debatably, ritual, is the frequent occurrence of natural pigments, such as <strong>ochre<\/strong> (red) and manganese dioxide (black) in Neanderthal sites that could have been used for art. However, the actual uses of pigments are unclear, as there is very little evidence of art or paintings in Mousterian sites. One exception may be the recent discovery in Spain of a perforated shell that appears to be painted with an orange pigment, which may be evidence of Neanderthal art and jewelry. However, many pigments also have properties that make them good emulsifiers in adhesive (like for attaching a stone tool to a wooden handle) or useful in tanning hides. So the presence of pigment may or may not be associated with symbolic thought; however, it definitely does show a technological sophistication beyond that of earlier Archaic hominins.<\/p>\n<div class=\"textbox shaded\" style=\"background: var(--lightblue)\">\n<h2>Dig Deeper: Evidence of Endocannibalism Among the Neanderthals<\/h2>\n<p>Krapina, a Neanderthal site in Croatia, has recently sparked new archeological discourse as many investigations upon fossilized remains show evidence of post-mortem modifications and manipulations of limbs and bones through the use of tools (Rougier Et al., 2016). These findings provide compelling evidence of Neanderthals engaging in cannibalism as part of their post-mortem practices. Additionally, these uncovered remains were found to have died of natural causes as opposed to being killed, showing that even the earliest humans may have had some sort of morality or ethics surrounding the cannibalizing of their kin, meaning they were aware of death in a social context as opposed to merely a physical one.<\/p>\n<p>While the original evidence in Krapina was uncovered in 1901, Croatian geologist and paleontologist Dragutin Gorjanovi\u0107-Kramberger\u2019s discovery of fragmented and burned human bones (Ullrich, 2005) was not yet confirmed to be linked to endocannibalism until much later. Whereas the discovery of burned bones does not mean they were being prepared for consummation, due to its context among other findings, this information supports the hypothesis that early hominids conducted post-mortem rituals and practices with their dead. Building on Gorjanovi\u0107-Kramberger\u2019s research, Herbert Ullrich wrote in <em>Anthropologie<\/em> (2005) that broken bones\u2014resulting from post-mortem bodily manipulations\u2014were \u201cdefleshed in preparation for secondary burial\u201d (2005, 251) and intentionally left outside rock shelters, while selectively chosen bones were seemingly brought inside for use in mortuary practices.<\/p>\n<p>For nearly 150 years, since the first Neanderthal skeletal remains were discovered, anthropologists and researchers have continued to debate the cognitive, social, and physical abilities of this species. In 2016, Rougier and colleagues wrote in <em>Scientific Reports<\/em>, furthering the research, presenting 99 new Neanderthal remains found in Goyet, Belgium. Among these remains, similar evidence of human-induced alterations was identified, including signs of butchering, consumption, and the use of bones to modify stone tools (Rougier Et al., 2016). This discovery provides significant support for the presence of cannibalistic behaviour among Northern European Neanderthals, contributing to the growing body of evidence that Neanderthals engaged with death in ways that reflect social awareness, ritual behaviour, and complex cultural practices.<\/p>\n<p><strong>Contemporary Cases of Prion Disease Related to Endocannibalism<\/strong><\/p>\n<p>The evidence of endocannibalism does not end with early hominids; with Australian medical anthropologists recording thousands of cannibalism-related prion disease occurrences present in populations up until 2009 (Radford &amp; Scragg, 2013). Following a mysterious epidemic of a new form of spongiform encephalopathy\u2013a \u201cprogressive degenerative disease of the central nervous system\u201d (2013, p.29)\u2013anthropological research regarding the the cultural mortuary rites within the Okapa region of Papua New Guinea have linked the newfound disease \u2018Kuru\u2019 to post-mortem consumption of human remains (Radford &amp; Scragg, 2013; Collinge Et al., 2006).<\/p>\n<p>Local oral histories collected during the first investigations by these researchers in the 1950s traced the earliest cases back to the 1920s, with detailed case histories. Epidemiological data revealed a strong correlation between the spread of Kuru and participation in mortuary feasts, in which the deceased were ritually consumed as part of funerary rites (2006, p. 2070). From 1957 to 2004, over 2,700 cases were reported, with mortality peaking at over 200 deaths annually in the late 1950s (2006, p.2070); however, following the cessation of cannibalism in the easly 1960s due to governmental efforts, natural transmission of the disease has stopped, dropping the death toll dramatically, with the \u201clast three single cases reported in 2005, 2007, and 2009\u201d (Radford &amp; Scragg, p.48).<\/p>\n<\/div>\n<h3 class=\"import-Normal\"><strong>The Lasting Gift of Neanderthals: Tantalizing New Directions for Resear<\/strong><strong>ch<\/strong><\/h3>\n<p class=\"import-Normal\">Examining the more recent time period in which Neanderthals lived and the extensive excavations completed across Europe allows for a much more complete archaeological record from this time period. Additionally, the increased cultural complexity such as complex tools and ritual behaviours expressed by Neanderthals left a more detailed record than previous hominins. Intentional burials enhanced preservation of the dead and potentially associated ritual behaviours. Such evidence allows for a more complete and nuanced picture of this species.<\/p>\n<figure style=\"width: 424px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image15-5.png\" alt=\"Museum exhibition of life-sized Neanderthal figure.\" width=\"424\" height=\"469\" \/><figcaption class=\"wp-caption-text\">Figure 12.12: Artistic reconstruction of Neanderthal at The Natural History Museum in Vienna, Austria. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Homo_neanderthalensis,_The_Natural_History_Museum_Vienna,_20210730_1223_1272.jpg\" target=\"_blank\">Homo neanderthalensis, The Natural History Museum Vienna, 20210730 1223 1272<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Jakubhal\" target=\"_blank\">Jakub Ha\u0142un<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/legalcode\" target=\"_blank\">CC BY 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Additional analyses are possible on many Neanderthal finds, due to increased preservation of bone, the amount of specimens that have been uncovered, and the recency in which Neanderthals lived. We should be cautious, however, to consider the potential bias of many Neanderthal sites. Overwhelmingly, Neanderthal skeletons are found complete, with injuries or evidence of disease in caves. Does this mean all Neanderthals lived a tough, disease-wrought life? Probably not. It does, however, indicate that the sick were cared for by others, and that they lived in environments that preserved their bodies incredibly well. These additional studies include the examination of dental calculus and even DNA analysis. While limited, samples of Neanderthal DNA have been successfully extracted and analysed. Research thus far has identified specific genetic markers that show some Neanderthals were light-skinned and probably red-haired with light eyes. Genetic analyses, different from the typical hominin reconstruction done with earlier species, allow scientists to further investigate soft tissue markers of Neanderthals and other more recent hominin species. These studies offer striking conclusions regarding Neanderthal traits, their physical appearance, and their culture, as reflected in these artists\u2019 reconstructions (Figure 12.12).<\/p>\n<figure style=\"width: 258px\" class=\"wp-caption alignright\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image17-4.png\" alt=\"Photograph of Dr. Svante P\u00e4\u00e4bo in a blue suit and red tie.\" width=\"258\" height=\"368\" \/><figcaption class=\"wp-caption-text\">Figure 12.13: Nobel Prize winner (2022) and pioneer in paleogenomic research, Dr. Svante P\u00e4\u00e4bo. Credit: <a href=\"https:\/\/upload.wikimedia.org\/wikipedia\/commons\/2\/26\/Professor_Svante_Paabo_ForMemRS_%28cropped%29.jpg\" target=\"_blank\">Professor Svante Paabo ForMemRS (cropped)<\/a> by Duncan.Hull is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Dr. Svante P\u00e4\u00e4bo (Figure 12.13), of the Max Planck Institute for Evolutionary Anthropology, has been at the forefront of much of this new research, largely in the form of genomic studies (The Nobel Prize 2022). Awarded the Nobel Prize for Physiology or Medicine in 2022, P\u00e4\u00e4bo is known primarily for his work with ancient DNA. He has successfully sequenced mitochondrial DNA (mtDNA) as well as the entire Neanderthal genome from nuclear DNA. His genomic work has led to the realization that Denisovans are genetically distinct from Neanderthals, as well as the recent identification of a Neanderthal father and teenage daughter, which he discovered by looking for unique DNA markers in the fossil record. Additionally, P\u00e4\u00e4bo\u2019s genomic work has provided researchers with additional lines of evidence regarding the connections between hominin fossils (such as Neanderthals) and modern people, their time of divergence, and current genetic overlap. The work of P\u00e4\u00e4bo has even formalized a new field of study within anthropology\u2014paleogenomics. To stay up to date with Dr. Svante P\u00e4\u00e4bo\u2019s work, be sure to follow his <a href=\"https:\/\/www.eva.mpg.de\/genetics\/neandertals-and-more\/overview\/\" target=\"_blank\">lab\u2019s website<\/a>.<\/p>\n<h3 class=\"import-Normal\"><strong>Neanderthal Culture: Communicating through Speech<\/strong><\/h3>\n<p class=\"import-Normal\">To successfully live in groups and to foster cultural innovations, Neanderthals would have required at least a basic form of communication in order to function, possibly using a speech-based communication system. The challenge with this line of research is that speech, of course, is not preserved, so indirect evidence must be used to support this conclusion. It is thought that Neanderthals would have possessed some basic speech, as evidenced from a variety of sources, including throat anatomy and genetic evidence (Lieberman 1971). There is only one bone in the human body that could demonstrate if a hominin was able to speak, or produce clear vocalizations like modern humans, and that is the hyoid, a U-shaped bone that is found in the throat and is associated with the ability to precisely control the vocal cords. Very few hyoid bones have been found in the archaeological record; however, a few have been uncovered in Neanderthal burials. The shape of the Neanderthal hyoid is nearly identical to that of modern humans, pointing to the likelihood that they had the same vocal capabilities as modern humans. In addition, geneticists have uncovered a mutation present in both modern humans and Neanderthals\u2014the FOXP2 gene\u2014that is possibly linked to the ability to speak. However, other scientists argue that we cannot make sweeping conclusions that the FOXP2 gene accounts for speech due to small sample size. Finally, scientists have also pointed to the increasingly complex cultural behaviour of Neanderthals as a sign that symbolic communication, likely through speech, would have been the only way to pass down the skills needed to make, for example, a Levallois blade or to position a body for intentional burial.<\/p>\n<h3 class=\"import-Normal\"><strong>Neanderthal Intelligence<\/strong><\/h3>\n<p class=\"import-Normal\">One of the enduring questions about Neanderthals centres on their intelligence, specifically in comparison to modern humans. Brain volume indicates that Neanderthals certainly had a large brain, but it continues to be debated if Neanderthals were of equal intelligence to modern humans. Remember, creatures with larger body sizes tend to have larger brains; however, scaling of the brain is not always associated with greater intelligence (Alex 2018). Brain volume (cranial capacity), cultural complexity, tool use, and compassion toward their kind all point to an increase in intellect among Neanderthals when compared to previous hominins.<\/p>\n<p class=\"import-Normal\">Yet, new research is suggesting additional differences between Neanderthal brains and our own. For example, Euluned Pearce and colleagues (2013), from the University of Oxford, noted the frontal lobes of Neanderthals and modern humans are almost identical. However, Neanderthals had a larger visual cortex\u2014the portion of the brain involved in processing visual information. This would have left Neanderthals with less brain tissue for other functions, including those that would have aided them in dealing with large social groupings, one of the differences that has been suggested to exist between Neanderthals and modern humans. Other differences were found when geneticist John Blangero, from the Texas Biomedical Research Institute, compared data from the Neanderthal genome against data from modern study participants. Blangero and his colleagues (Blangero Et al. 2014) discovered that some Neanderthal brain components were very different, and smaller, than those in the modern sample. Differences were found in areas associated with the processing of information and controlling emotion and motivation, as well as overall brain connectivity. In short, as Blangero stated, \u201cNeanderthals were certainly cognitively adept,\u201d although their specific abilities may have differed from modern humans\u2019 in key areas (qtd. in Wong 2015). This point has been echoed in other recent genetic studies comparing Neanderthal and anatomically modern human brains (el-Showk 2019).<\/p>\n<p class=\"import-Normal\">Finally, scientists are fairly certain that Neanderthal brain development after birth was not the same as that of modern humans. After birth, anatomically modern <em>Homo sapiens <\/em>babies go through a critical period of brain expansion and cognitive development. It appears that Neanderthal babies\u2019 brains and bodies did not follow the same developmental pattern (Smith Et al. 2010; Zollikofer and Ponce de Le\u00f3n 2013). Modern humans enjoy an extended period of childhood, which allows children to engage in imaginative play and develop creativity that fosters cognitive skills. Neanderthals had a more limited childhood, with less development of the creative mind that may have affected their species\u2019 success (Nowell 2016).<\/p>\n<p class=\"import-Normal\">The exact nature of Neanderthal intelligence remains under investigation, however. Some studies disagree with the idea that Neanderthal intelligence had limitations compared to our own, noting the extensive evidence of Neanderthals having limb asymmetry. Their tools also have wear marks indicating that they were hand-dominant. This is further supported by marks on Neanderthal teeth that demonstrate hand dominance. The Neanderthal \u201cstuff-and-cut method\u201d of eating, noted by David Frayer and colleagues (Frayer Et al. 2012), would have seen Neanderthals hold a piece of meat in their teeth, while pulling it taut with one hand, and then using the other hand, their dominant one, to cut the meat off of the larger slab being held in their teeth. When looking at 17 Neanderthals and their tooth wear, only two do not show markings associated with a right-hand dominant individual eating in this manner. Further, it has been established that favouring the right hand is a key marker between modern humans and chimpanzees, and that handedness also relates to language development, in the form of bilateral brain development. That Neanderthals likely were hand-dominant suggests they had an indicator of bilateral brain development and a precondition for human speech.<\/p>\n<h2 class=\"import-Normal\">The Middle Stone Age: Neanderthal Contemporaries in Africa<\/h2>\n<p class=\"import-Normal\">While Neanderthals made their home on and adapted to the European and Asian continents, evidence of fossil humans in Africa show they were also adapting to their local environments. These populations in Africa exhibit many more similarities to modern humans than Neanderthals, as well as overall evolutionary success. While the African fossil sample size is smaller and more fragmentary than the number of Neanderthal specimens across Europe and Asia, the African sample is interesting in that it represents a longer time period and larger geographical area. This group of fossils\u2014often represented by the name \u201cMiddle Stone Age,\u201d or MSA\u2014dates to between 300,000 and 30,000 years ago across the entire continent of Africa. As with Archaic <em>Homo sapiens<\/em>, there is much variability seen in this African set of fossils. There are also a few key consistent elements: none of them exhibit Neanderthal skeletal features; instead, they demonstrate features that are increasingly consistent with anatomically modern <em>Homo sapiens<\/em>.<\/p>\n<p class=\"import-Normal\">Similarities to Neanderthals and MSA contemporaries in Africa are seen, however, in their behavioural adaptations, including stone tools and other cultural elements. The tools associated with the specimens living in Africa during this time period are, like their physical features, varied. In some parts of Africa, namely Northern Africa, stone tools from this time so closely resemble Neanderthal tools that they are classified as Mousterian. In sub-Saharan Africa, the stone tools associated with these specimens are labeled as MSA. Some scholars argue that these could also be a type of Mousterian tools, but they are still typically subdivided based on geographical location.<\/p>\n<p class=\"import-Normal\">Recall that Mousterian tools were much more advanced than their Acheulean predecessors in terms of how the stone tools were manufactured, the quality of the stones used, and the ultimate use of the tools that were made. In addition, recent evidence suggests that MSA tools may also have been heat treated\u2014to improve the quality of the stone tool produced (Stolarczyk and Schmidt 2018). Evidence for heat treating is seen not only through advanced analysis of the tool itself but also through the residue of fires from this time period. Fire residues show a shift over time from small, short fires fuelled by grasses (probably intended for cooking) to larger, more intensive fires that required the exploitation of dry wood, exactly the type of fire that would have been needed for heat treating stone tools (Esteban Et al. 2018).<\/p>\n<p class=\"import-Normal\">Other cultural elements seen with MSA specimens include the use of marine (sea-based) resources for their diet (Parkington 2003), manufacture of bone tools, use of adhesive and compound tools (e.g., hafted tools), shell bead production, engraving, use of pigments (such as ochre), and other more advanced tool-making technology (e.g., microlithics). While many of these cultural elements are also seen to a limited extent among Neanderthals, developments at MSA sites appear more complex. This MSA cultural expansion may have been a response to climate change or an increased use of language, complex communication, and\/or symbolic thought. Others have suggested that the MSA cultural expansion was due to the increase of marine resources in their diet, which included more fatty acids that may have aided their cognitive development. Still others have suggested that the increased cultural complexity was due to increased interaction among groups, which spurred competition to innovate. Recent studies suggest that perhaps the best explanation for the marked cultural complexity of MSA cultural artifacts is best explained by the simple fact that they lived in diverse habitats (Kandel Et al. 2015). This would have necessitated a unique set of cultural adaptations for each habitat type (for example, specialized marine tools would have been needed along coastal sites but not at inland locations). Simply put, the most useful adaptation of MSA was their flexibility of behaviour and adaptability to their local environment. As noted previously in this chapter, flexibility of behaviour and physical traits, rather than specialization, seems to be a feature that was favoured in hominin evolution at this time.<\/p>\n<h2 class=\"import-Normal\">Where Did They Go? The End of Neanderthals<\/h2>\n<p class=\"import-Normal\">While MSA specimens were increasingly successful and ultimately transitioned into modern <em>Homo sapiens<\/em>, Neanderthals disappeared from the fossil record by around 40,000 years ago. What happened to them? We know, based on genetics, that modern humans come largely from the modern people who occupied Africa around 300,000 to 100,000 years ago, at the same time that Neanderthals were living in northern Europe and Asia. As you will learn in Chapter 13, modern humans expanded out of Africa around 150,000 years ago, rapidly entering areas of Europe and Asia inhabited by Neanderthals and other Archaic hominins. Despite intense interest and speculation in fictional works about possible interactions between these two groups, there is very little direct evidence of either peaceful coexistence or aggressive encounters. It is clear, though, that these two closely related hominins shared Europe for thousands of years, and recent DNA evidence suggests that they occasionally interbred (Fu Et al. 2015). Geneticists have found traces of Neanderthal DNA (as much as 1% to 4%) in modern humans of European and Asian descent not present in modern humans from sub-Saharan Africa. This is indicative of limited regional interbreeding with Neanderthals.<\/p>\n<p class=\"import-Normal\">While some interbreeding likely occurred, as a whole, Neanderthals did not survive. What is the cause for their extinction? This question has fascinated many researchers and several theories\u00a0have been suggested, including:<\/p>\n<ul>\n<li class=\"import-Normal\">At the time that Neanderthals were disappearing from the fossil record, the climate went through both cooling and warming periods\u2014each of which posed challenges for Neanderthal survival (Defleur and Desclaux 2019; Staubwasser Et al. 2018). It has been argued that as temperatures warmed, large-bodied animals, well adapted to cold weather, moved farther north to find colder environments or faced extinction. A shifting resource base could have been problematic for continued Neanderthal existence, especially as additional humans, in the form of modern <em>Homo sapiens<\/em>, began to appear in Europe and compete for a smaller pool of available resources.<\/li>\n<li class=\"import-Normal\">It has been suggested that the eruption of a European volcano 40,000 years ago could have put a strain on available plant resources (Golovanova Et al. 2010). The eruption would have greatly affected local microclimates, reducing the overall temperature enough to alter the growing season.<\/li>\n<li class=\"import-Normal\">Possible differences in cognitive development may have limited Neanderthals in terms of their creative problem solving. As much as they were biologically specialized for their environment, the nature of their intelligence might not have offered them the creative problem-solving skills to innovate ways to adapt their culture when faced with a changing environment (Pearce Et al. 2013).<\/li>\n<li class=\"import-Normal\">CRISPR gene-editing technology has been used in studies to evaluate potential differences between human and Neanderthal brains, based on differences in the genetic code. Potential differences include a Neanderthal propensity for mutations related to brain development that could account for more rapid brain development, maturation, synapse misfires, and less-orderly neural processes (Mora-Berm\u00fadez Et al. 2022; Trujillo Et al. 2021). Fundamental differences in brain function at the cellular level may account for the differential survival rates of Neanderthal and modern human populations.<\/li>\n<li class=\"import-Normal\">There is evidence that suggests reproduction may have posed challenges for Neanderthals. Childbirth was thought to have been at least as difficult for female Neanderthals as anatomically modern <em>Homo sapiens<\/em> (Weaver and Hublin 2009). Female Neanderthals may have become sexually mature at an older age, even older than modern humans. This delayed maturation could have kept the Neanderthal population size small. A recent study has further suggested that male Neanderthals might have had a genetic marker on the Y chromosome that could have caused incompatibility between the fetus and mother during gestation; this would have had severe consequences for birth rate and survival (Mendez Et al. 2016). Even a small but continuous decrease in fertility would have been enough to result in the extinction of Neanderthals (Degioanni Et al. 2019).<\/li>\n<li class=\"import-Normal\">As mentioned above, the end of Neanderthal existence overlaps with modern human expansion into northern Europe and Asia. There is no conclusive direct evidence to indicate that Neanderthals and modern humans lived peacefully side by side, nor that they engaged in warfare, but by studying modern societies and the tendencies of modern humans, it has been suggested that modern humans may not have warmly embraced their close but slightly odd-looking cousins when they first encountered them (Churchill Et al. 2009). Nevertheless, direct competition with modern humans for the same resources may have contributed to the Neanderthals\u2019 decline (Gilpin Et al. 2016); it may also have exposed them to new diseases, brought by modern humans (Houldcroft and Underdown 2016), which further decimated their population. Estimates of energy expenditures suggest Neanderthals had slightly higher caloric needs than modern humans (Venner 2018). When competing for similar resources, the slightly greater efficiency of modern humans might have helped them experience greater success in the face of competition\u2014at a cost to Neanderthals.<\/li>\n<\/ul>\n<p class=\"import-Normal\">It has been suggested that the Neanderthal populations were fairly small to begin with (estimated between 5,000 and 70,000 individuals; Bocquet-Appel and Degioanni 2013), one or a combination of these factors could have easily led to their demise. As more research is conducted, we will likely get a better picture of exactly what led to Neanderthal extinction.<\/p>\n<h2 class=\"import-Normal\">Denisovans<\/h2>\n<figure style=\"width: 353px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image16-4.png\" alt=\"Small fossilized finger bone sitting atop a chalk outline of hand bones.\" width=\"353\" height=\"235\" \/><figcaption class=\"wp-caption-text\">Figure 12.14: Reproduction of Denisovan finger bone. Credit: <a href=\"https:\/\/upload.wikimedia.org\/wikipedia\/commons\/6\/6f\/Denisova_Phalanx_distalis.jpg\" target=\"_blank\">Denisova Phalanx distalis<\/a> (image from Museum of Natural Sciences, Brussels, Belgium) by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Thilo_Parg\" target=\"_blank\">Thilo Parg<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">While Neanderthals represent one regionally adapted branch of the Archaic <em>Homo sapiens <\/em>family tree, recent discoveries in Siberia and the Tibetan Plateau surprised paleoanthropologists by revealing yet another population that was contemporary with Archaic <em>Homo sapiens<\/em>, Neanderthals, and modern <em>Homo sapiens<\/em>. The genetic analysis of a child\u2019s finger bone (Figure 12.14) and an adult upper third molar (Figure 12.15) from Denisova Cave in the Altai Mountains in Siberia by a team including Svante P\u00e4\u00e4bo discovered that the mitochondrial and nuclear DNA sequences reflected distinct genetic differences from all known Archaic populations. Dubbed \u201cDenisovans\u201d after the cave in which the bones were found, this population is more closely related to Neanderthals than modern humans, suggesting the two groups shared an ancestor who split from modern humans first, then the Neanderthal-Denisovan line diverged more recently (Reich Et al. 2010).<\/p>\n<figure style=\"width: 227px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image6-4-1.png\" alt=\"Molar tooth with wear, large surface area, and large roots.\" width=\"227\" height=\"341\" \/><figcaption class=\"wp-caption-text\">Figure 12.15: Reproduction of Denisovan molar. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Denisova_Molar.jpg\" target=\"_blank\">Denisova Molar<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Thilo_Parg\" target=\"_blank\">Thilo Parg<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Denisovans share up to 5% of their DNA with modern Melanesians, aboriginal Australians, and Polynesians, and 0.2% of their DNA with other modern Asian populations and Native Americans. Additional studies have suggested one (Vernot Et al. 2018) or two (Browning Et al. 2018) separate points of time when interbreeding occurred between modern humans and Denisovans.<\/p>\n<p class=\"import-Normal\">Genetic analysis reveals that Denisovans (potentially three distinct populations) had adaptations for life at high altitudes that prevented them from developing altitude sickness and hypoxia in extreme environments such as Tibet, where the average annual temperature is close to 0\u2103 and the altitude is more than a kilometre (about 4,000 feet) above sea level. Through protein analysis of a jawbone, one study (Chen Et al. 2019) has placed Denisovans in Tibet as early as 160,000 years ago. Genetic evidence of interbreeding has linked modern Tibetan populations with Denisovans 30,000 to 40,000 years ago, which implies that the unique high-altitude adaptations seen in modern Tibetans may have originated with Denisovans (Huerta-Sanchez Et al. 2014).<\/p>\n<p class=\"import-Normal\">Other research suggests tantalizing new directions regarding Denisovans. Stone tools similar to those found in Siberia have been uncovered in the Tibetan plateau suggesting a connection between the Denisovan populations in those two areas (Zhang Et al. 2018). The molar of a young girl, possibly Denisovan, has been found in Laos and shows strong similarities to specimens from China (Demeter Et al. 2022). And DNA sequencing from discoveries in the Denisova Cave have yielded a genome that has been interpreted as the first-generation offspring of a Denisovan father and Neanderthal mother (Slon Et al. 2018). While this research is not yet conclusive and is still being interpreted, exciting new possibilities are being revealed. To stay up-to-date with new discoveries, consider following organizations such as the <a href=\"https:\/\/www.facebook.com\/smithsonian.humanorigins\/\" target=\"_blank\">Smithsonian\u2019s Human Origins Program<\/a> on social media.<\/p>\n<div class=\"textbox\" style=\"background: var(--lightblue)\">\n<h2>Pleistocene Hominins in East Asia: Homo longi and Yunxian<\/h2>\n<p>New fossil discoveries, along with advanced molecular analysis, are prompting re-evaluations of the complex evolutionary dynamics of non-sapiens Homo in the middle-late Pleistocene.<\/p>\n<h3>Homo longi<\/h3>\n<p>The Harbin cranium, often referred to as Homo longi, represents one of the most remarkable Middle Pleistocene human fossils discovered in East Asia. It is currently carbon-dated at 146 ka, allowing recent scholarship to use the Harbin cranium to argue for a distinct clade of hominins that evolved independently in Eastern Asia, separate from Neanderthals and modern humans (Ni et al., 2021). This clade is argued to include Dali, Jinniushan, Hualongdong, Xiahe, and Harbin, based on phylogenetic analyses using parsimony criteria and Bayesian tip-dating, forming a third East Asian lineage and a sister group to the Homo sapiens lineage.<\/p>\n<p>The Harbin cranium exhibits a unique combination of traits, likely representing a species of Homo distinct from other Middle-to-Late Pleistocene taxa, including H. sapiens, H. Neanderthalensis, and H. Heidelbergensis\/H. Rhodesiensis. Its overall size is exceptional, setting it apart from nearly all other known fossils; however, the proportions of the cranial vault align closely with those of other large late archaic Homo species, with an estimated brain volume of approximately 1,420 mL. Despite its considerable breadth, the face is relatively low in height and exhibits a zygomaxillary shape similar to that seen in H. sapiens and H. antecessor, a feature also observed in other Middle Pleistocene Chinese fossils from Dali and Jinniushan. Additionally, the face is attached to the braincase with reduced prognathism, forming a more perpendicular angle as in modern humans, in contrast to the pronounced midfacial prognathism of Neanderthals.<\/p>\n<h3>Yunxian, China: Possible cladistic origins<\/h3>\n<p>In 2025, researchers released findings that expanded the diversity and relationships of Homo lineages in the Pleistocene, based on an analysis of fossils found in 1989\/90. Two skull fossils were found near the Hanjiang River in Hubei province, China, and were named the Yunxian 1 and Yunxian 2 crania\u2014A third cranium has recently been discovered in the same sediment layer as the two previous finds (Tu et al., 2026). The first 2 specimens were in poor condition, fragmented and distorted; however, using recently developed techniques such as high-resolution computed tomography (CT) scans, image segmentation, and digital repositioning of fragments, the researchers incorporated elements from the Yunxian 1 crania with the less damaged Yunxian 2 cranium. The Yunxian 2 cranium is a mosaic of primitive and derived traits. It retains ancient characteristics seen in earlier hominins, a thick supraorbital torus, a broad palate, a long and low vault in lateral view, and a receding frontal contour; its frontal lobe remains low and narrow, similar to H. erectus fossils. Conversely, it lacks the strongly angulated occipital bone found in H. erectus as well as the protruding occipital region or central suprainiac fossa typical of Neanderthals. The big surprise is that the zygomaxillary region is transversely flat and faces anteriorly, a feature comparable to the Hualongdong and Harbin fossils and even H. sapiens. This intermediate morphology places Yunxian 2 in a distinct position, linking archaics like H. erectus with later Asian hominins such as Harbin, Dali, and Jinniushan. Phylogenetic and morphometric analyses confirm that Yunxian 2 represents an early member of the Asian H.longi Clade. The reconstructed Yunxian 2 cranium represents a major achievement in paleoanthropology, digitally restoring a badly damaged fossil from beyond the Middle Pleistocene. In fact, recent discussion suggests an even earlier date for the Yunxian fossils at approximately 1.77 Ma (Tu et al., 2026). In their analysis, they identify the Yunxian fossils as H.erectus, and the site as Early Pleistocene. Over 500 artifacts have been recovered from the site (cores, choppers, and flakes) typical of the Early Paleolithic. Nevertheless, the mosaic morphology of the Yunxian skulls reveals characteristics within the range of both H. erectus and the Harbin skull (among others), which may position these finds as being very close to the origins and diversification of the longi clade, as well as preserving transitional features close to the sapiens clade\u00a0 (Feng et al., 2025, p.1323).<\/p>\n<p>The expanding fossil and genomic record of Archaic Homo has profoundly reshaped our understanding of Pleistocene human evolution. Discoveries, from an increasing variety of fossils found in eastern Asia, to advances in genomic research, demonstrate that multiple contemporaneous lineages once coexisted, interacted, diverged and, at times, interbred. These findings challenge earlier linear models of human ancestry and instead point to a dynamic evolutionary landscape marked by regional diversification, intermittent contact, and complex patterns of gene flow.<\/p>\n<\/div>\n<p>&nbsp;<\/p>\n<h2 class=\"import-Normal\">How Do These Fit In? <em>Homo naledi<\/em> and <em>Homo floresiensis<br \/>\n<\/em><\/h2>\n<p class=\"import-Normal\">Recently, some fossils have been unearthed that have challenged our understanding of the hominin lineage. The fossils of <em>Homo <\/em><em>naledi<\/em> and <em>Homo <\/em><em>floresiensis<\/em> are significant for several reasons but are mostly known for how they don\u2019t fit the previously held patterns of hominin evolution. While we examine information about these species, we ask you to consider the evidence presented in this chapter and others to draw your own conclusions regarding the significance and placement of these two unusual fossil species in the hominin lineage.<\/p>\n<h3 class=\"import-Normal\"><strong>Homo <\/strong><strong>naledi<\/strong><\/h3>\n<figure style=\"width: 347px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image12-5.png\" alt=\"A nearly complete skeleton surrounded by off-white bone fragments on a black table.\" width=\"347\" height=\"390\" \/><figcaption class=\"wp-caption-text\">Figure 12.16: A sample of some of the 1,550 bones found representing Homo naledi. Credit: <a href=\"https:\/\/elifesciences.org\/articles\/09560#fig1\" target=\"_blank\">Dinaledi skeletal specimens (Figure 1)<\/a> by <a href=\"https:\/\/elifesciences.org\/articles\/09560\" target=\"_blank\">Berger et al. 2015<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/legalcode\" target=\"_blank\">CC BY 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">In 2013 recreational spelunkers uncovered a collection of bones deep in a cave network in Johannesburg, South Africa. The cave system, known as Rising Star, had been well documented by other cavers; however, it appears few people had ever gone as far into the cave as these spelunkers did. Lee Berger, paleoanthropologist at University of Witwatersrand, in Johannesburg, immediately put out a call for what he termed \u201cunderground astronauts\u201d to begin recovery and excavation of the fossil materials. Unlike other excavations, Berger and most other paleoanthropologists would not be able to access the elusive site, as it was incredibly difficult to reach, and at some points there was only eight inches of space through which to navigate. The underground astronauts, all petite women anthropologists, were the only ones who were able to access this remarkable site. Armed with small excavation tools and a video camera, which streamed the footage up to the rest of the team at the surface, the team worked together and uncovered a total of 1,550 bones, representing at least 15 individuals, as seen in Figure 12.16. Later, an additional 131 bones, including an almost-complete cranium, were found in a nearby chamber of the cave, representing three more individuals (Figure 12.17). Berger called in a team of specialists to participate in what was dubbed \u201cPaleoanthropology Summer Camp.\u201d Each researcher specialized in a different portion of the hominin skeleton. With various specialists working simultaneously, more rapid analysis was possible of <em>Homo <\/em><em>naledi<\/em> than most fossil discoveries.<\/p>\n<p>&nbsp;<\/p>\n<figure style=\"width: 534px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image2-4.png\" alt=\"Photograph of four different views of the LES1 Homo naledi skull set against a black background.\" width=\"534\" height=\"599\" \/><figcaption class=\"wp-caption-text\">Figure 12.17: Several angles of the nearly complete LES1 Homo naledi skull. Credit: <a href=\"https:\/\/elifesciences.org\/articles\/24232#fig5\" target=\"_blank\">LES1 Cranium (Figure 5)<\/a> by <a href=\"https:\/\/elifesciences.org\/articles\/24232\" target=\"_blank\">Hawks et al. 2017<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/legalcode\" target=\"_blank\">CC BY 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">While access to the site, approximately 80 m from any known cave entrance or opening, was treacherous for researchers, it must have been difficult for <em>Homo <\/em><em>naledi<\/em> as well. The route included moving through a portion that is just 25 cm wide at some points, known as \u201cSuperman\u2019s Crawl.\u201d The only way to get through this section is by crawling on your stomach with one arm by your side and the other raised above your head. Past Superman\u2019s Crawl, a jagged wall known as the Dragon\u2019s Back would have been very difficult to traverse. Below that, a narrow vertical chute would have eventually led down to the area where the fossils were discovered. While geology changes over time and the cave system likely has undergone its fair share, it is not likely that these features arose after <em>Homo <\/em><em>naledi<\/em> lived (Dirks Et al. 2017). This has made scientists curious as to how the bones ended up in the bottom of the cave system in the first place. It has been suggested that <em>Homo <\/em><em>naledi<\/em> deposited the bones there, one way or another. If <em>Homo <\/em><em>naledi<\/em> did deposit the bones, either through random disposal or intentional burial, this raises questions regarding their symbolic behaviour and other cultural traits, including the use of fire, to access a very dark cave system. Another competing idea is that a few individuals may have entered the cave system to escape a predator and then got stuck. To account for the sheer number of fossils, this would have had to happen multiple times.<\/p>\n<p class=\"import-Normal\">The features of <em>Homo <\/em><em>naledi<\/em> are well-documented due to the fairly large sample, which represents individuals of all sexes and a wide range of ages. The skull shape and features are very much like other members of the genus <em>Homo<\/em>\u2014including a sagittal keel and large brow, like <em>Homo <\/em><em>erectus<\/em>, and a well-developed frontal lobe, similar to modern humans\u2014yet the brain size is significantly smaller than its counterparts, at approximately 500 cc (560 cc for males and 465 cc for females). The teeth also exhibit features of later members of the genus <em>Homo<\/em>, such as Neanderthals, including a reduction in overall tooth size. <em>Homo <\/em><em>naledi<\/em> also had unique shoulder anatomy and curved fingers, indicating similarities to tree-dwelling primates, which is very different from any other hominin yet found. Perhaps the greatest shock of all is that <em>Homo <\/em><em>naledi<\/em> has been dated to 335,000 to 236,000 years ago, placing it as a contemporary to modern <em>Homo sapiens,<\/em> despite its very primitive features. An additional specimen of a child, found in 2021, not only shares many of the unique features found in the adult specimen but will also add insight into the growth and development of individuals of this species (Brophy Et al. 2021).<\/p>\n<h3 class=\"import-Normal\"><strong>Homo <\/strong><strong>floresiensis<\/strong><\/h3>\n<p class=\"import-Normal\">In a small cave called Liang Bua, on the island of Flores, in Indonesia, a small collection of fossils were discovered beginning in 2003 (Figure 12.18). The fossil fragments represent as many as nine individuals, including a nearly complete female skeleton. The features of the skull are very similar to that of <em>Homo <\/em><em>erectus<\/em>, including the presence of a sagittal keel, an arching brow ridges and nuchal torus, and the lack of a chin (Figure 12.19). <em>Homo <\/em><em>floresiensis<\/em>, as the new species is called, had a brain size that was remarkably small at 400 cc, and recent genetic studies suggest a common ancestor with modern humans that predates <em>Homo <\/em><em>erectus<\/em>.<\/p>\n<figure style=\"width: 606px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image8-3.png\" alt=\"View from inside a large cave with people standing near a dug-out square of dirt.\" width=\"606\" height=\"403\" \/><figcaption class=\"wp-caption-text\">Figure 12.18: Liang Bua Cave on the island of Flores, in Indonesia, where a collection of Homo floresiensis specimens were discovered. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Homo_floresiensis_cave.jpg\" target=\"_blank\">Homo floresiensis cave<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/84301190@N00\" target=\"_blank\">Rosino<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\" target=\"_blank\">CC BY-SA 2.0 License<\/a>.<\/figcaption><\/figure>\n<figure style=\"width: 584px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image9-5.png\" alt=\"Photograph of a gray and off-white cast Homo floresiensis skull.\" width=\"584\" height=\"584\" \/><figcaption class=\"wp-caption-text\">Figure 12.19: Homo floresiensis had a brain that was remarkably small at 400 cc. Recent genetic studies suggest a common ancestor with modern humans that predates Homo erectus. Credit: <a href=\"https:\/\/boneclones.com\/product\/homo-floresiensis-skull-BH-033-2\" target=\"_blank\">Homo floresiensis Skull (Flores Skull LB1)<\/a> by <a href=\"https:\/\/boneclones.com\/\" target=\"_blank\">\u00a9BoneClones<\/a> is used by permission and available here under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">The complete female skeleton, who was an adult, was approximately a metre tall and would have weighed just under 30 kg, which is significantly shorter and just a few kilograms more than the average, modern, young elementary-aged child. A reconstructed comparison between an anatomically modern human and <em>Homo <\/em><em>floresiensis<\/em> can be seen in Figure 12.20. The small size of the fossil has earned the species the nickname \u201cthe Hobbit.\u201d Many questions have been asked about the stature of this species, as all of the specimens found also show evidence of diminutive stature and small brain size. Some explanations include pathology; however, this seems unlikely as all fossils found thus far demonstrate the same pattern. Another possible explanation lies in a biological phenomena seen in other animal species also found on the island, which date to a similar time period. This phenomenon, called <strong>insular dwarfing<\/strong>, is due to limited food resources on an island, which can create a selective pressure for large-bodied species to be selected for smaller size, as an island would not have been able to support their larger-bodied cousins for a long period of time. This phenomenon is the cause of other unique species known to have lived on the island at the same time, including the miniature stegodon, a dwarf elephant species.<\/p>\n<figure style=\"width: 448px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image18-4.png\" alt=\"Black-and-white drawing of a large nude woman and a much smaller man.\" width=\"448\" height=\"611\" \/><figcaption class=\"wp-caption-text\">Figure 12.20: A reconstructed comparison between an anatomically modern human and Homo floresiensis. As an adult, Homo floresiensis was approximately 1 metre tall and would have weighed under 30 kg. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-16\/\" target=\"_blank\">Anatomically modern human and Homo floresiensis (Figure 11.19)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">There is ongoing research and debate regarding <em>Homo floresiensis<\/em>\u2019 dates of existence, with some researchers concluding that they lived on Flores until perhaps as recently as 17,000 years ago, although they are more often dated to 100,000 to 60,000 years ago. Stone tools from that time period uncovered at the site are similar to other hominin stone tools found on the island of Flores. <em>Homo <\/em><em>floresiensis<\/em> would have hunted a wide range of animals, including the miniature stegodon, giant rats, and other large rodents. Other animals on the island that could have threatened them include the giant komodo dragon. An interesting note about this island chain is that ancestors of <em>Homo <\/em><em>floresiensis<\/em> would have had to traverse the open ocean in order to get there, as the nearest island is almost 10 km away, and there is little evidence to support that a land bridge connecting mainland Asia or Australia to the island would have been present. This separation from the mainland would also have limited the number of other animals, including predators and human species, that would have had access to the island. Anatomically modern <em>Homo sapiens<\/em> arrived on the island around 30,000 years ago and, if some researchers\u2019 later dates for <em>Homo <\/em><em>floresiensis<\/em> are correct, both species may have lived on Flores at the same time. The modern population living on the island of Flores today believes that their ancestors came from the Liang Bua cave; however, recent genetic studies have determined they are not related to <em>Homo <\/em><em>floresiensis<\/em> (Tucci Et al. 2018).<\/p>\n<h2 class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">Hominin Species Summaries<\/span><\/h2>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<tbody>\n<tr class=\"Table3-R\" style=\"height: 0\">\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Hominin<\/strong><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Archaic <em>Homo sapiens<\/em><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 0\">\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dates<\/strong><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">600,000\u2013200,000 years ago (although some regional variation)<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 0\">\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Region(s)<\/strong><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Africa, Europe, and Asia<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 0\">\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Famous discoveries<\/strong><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Broken Hill (Zambia), Atapuerca (Spain)<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 0\">\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Brain size<\/strong><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1,200 cc average<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 0\">\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dentition<\/strong><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Slightly smaller teeth in back of mouth, larger front teeth<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 0\">\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Cranial features<\/strong><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Emerging forehead, no chin, projecting occipital region<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 0\">\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Postcranial features<\/strong><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Robust skeleton<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 0\">\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Culture<\/strong><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Varied regionally, but some continue to use Acheulean handaxe, others adopt Mousterian tool culture<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 0\">\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Other <\/strong><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Lots of regional variation in this species<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<tbody>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Species<\/strong><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><em>Homo <\/em><em>naledi<\/em><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dates<\/strong><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">335,000\u2013236,000 years ago<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Region(s)<\/strong><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">South Africa<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Famous discoveries<\/strong><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Rising Star Cave<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Brain size<\/strong><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">500 cc average<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dentition<\/strong><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Reduced tooth size<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Cranial features<\/strong><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Sagittal keel, large brow, well-developed frontal region<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Postcranial features<\/strong><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Suspensory shoulder<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Culture<\/strong><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">unknown<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Other<\/strong><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">N\/A<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<tbody>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Hominin<\/strong><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Neanderthals<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dates<\/strong><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">150,000\u201340,000 years ago<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Region(s)<\/strong><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Western Europe, Middle East, and Western Asia only<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Famous discoveries<\/strong><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Shanidar (Iraq), La Chapelle-aux-Saints (France)<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Brain size<\/strong><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1500 cc average<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dentition<\/strong><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Retromolar gap<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Cranial features<\/strong><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Large brow ridge, midfacial prognathism, large infraorbital foramina, occipital bun<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Postcranial features<\/strong><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Robust skeleton with short and stocky body, increased musculature, barrel chest<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Culture<\/strong><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Mousterian tools often constructed using the Levallois technique<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Other<\/strong><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">N\/A<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<tbody>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Species<\/strong><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><em>Homo <\/em><em>floresiensis<\/em><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dates<\/strong><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">100,000\u201360,000 years ago, perhaps as recently as 17,000 years ago<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Region(s)<\/strong><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Liang Bua, island of Flores, Indonesia<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Famous discoveries<\/strong><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">\u201cThe Hobbit\u201d<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Brain size<\/strong><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">400 cc average<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dentition<\/strong><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">unknown<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Cranial features<\/strong><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Sagittal keel, arching brow ridges, nuchal torus, no chin<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Postcranial features<\/strong><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Very short stature (approximately 3.5 ft.)<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Culture<\/strong><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Tools similar to other tools found on the island of Flores<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Other<\/strong><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">N\/A<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<tbody>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Hominin<\/strong><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Denisovans<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dates<\/strong><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">100,000\u201330,000 years ago<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Region(s)<\/strong><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Siberia<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Famous discoveries<\/strong><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Child\u2019s finger bone and adult molar<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Brain size<\/strong><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">unknown<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dentition<\/strong><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Large molars (from limited evidence)<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Cranial features<\/strong><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">unknown<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Postcranial features<\/strong><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">unknown<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Culture<\/strong><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">unknown<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Other <\/strong><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Closely related to Neanderthals (genetically)<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div class=\"textbox shaded\">\n<h2 class=\"import-Normal\">Summary<\/h2>\n<p class=\"import-Normal\">Research presented in the chapter contributes to why scientists have taken to nicknaming this time period \u201cthe muddle in the middle.\u201d We know that the Middle Pleistocene picks up from <em>Homo erectus <\/em>and ends with the appearance of anatomically modern <em>Homo sapiens<\/em>. While the start and the end are clear, it\u2019s the middle that is messy. As more research is conducted and more data is collected, rather than clarifying our understanding of the hominin lineage during this time period, it only inspires more questions, particularly about the relationships between hominins during this time period, including the oft-misunderstood Neanderthal. Research is painting a more detailed picture of Neanderthal intelligence and both biological and behavioural adaptations. At the same time, their relationship to other Middle Pleistocene hominins, including Denisovans, as well as modern humans, remains unclear.<\/p>\n<p class=\"import-Normal\"><em>Homo<\/em> <em>naledi<\/em> and <em>Homo <\/em><em>floresiensis<\/em> are clear outliers when compared to their contemporary hominin species. Each has surprised paleoanthropologists for both their archaic traits in relatively modern times and their unique combination of traits seen in archaic species and modern humans. While these finds have been exciting, they have also completely upended the assumed trajectory of the human lineage, causing scientists to re-examine assumptions about hominin evolution and what it means to be modern. Add this to the developments being made using ancient DNA, other new fossil discoveries, and other innovations in paleoanthropology, and you see that our understanding of Archaic <em>Homo sapiens<\/em> and others living during this time period is rapidly developing and changing. This is a true testament to the nature of science and the scientific method.<\/p>\n<p class=\"import-Normal\">Clearly, hominins of the Middle Pleistocene are distinct from our species today. Yet, understanding the hominins that directly preceded our species and clarifying the evolutionary relationships between us is important to better understanding our own place in nature.<\/p>\n<h2 class=\"import-Normal\">Review Questions<\/h2>\n<ul>\n<li>What physical and cultural features are unique to Archaic<em> Homo sapiens<\/em>? How are Archaic<em> Homo sapiens<\/em> different in both physical and cultural characteristics from <em>Homo <\/em><em>erectus<\/em>?<\/li>\n<li>Describe the specific changes to the brain and skull first seen in Archaic<em> Homo sapiens<\/em>. Why does the shape of the skull change so dramatically from <em>Homo <\/em><em>erectus<\/em>?<\/li>\n<li>What role did the shifting environment play in the adaptation of Archaic <em>Homo sapiens<\/em>, including Neanderthals? Discuss at least one physical feature and one cultural feature that would have assisted these groups in surviving the changing environment.<\/li>\n<li>What does the regional variation in Archaic <em>Homo sapiens<\/em> represent in terms of the broader story of our species\u2019 evolution?<\/li>\n<li>Describe the issues raised by the discoveries of <em>Homo <\/em><em>naledi<\/em> and <em>Homo <\/em><em>floresiensis<\/em> in the understanding of the story of the evolution of <em>Homo sapiens<\/em>.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<h2 class=\"__UNKNOWN__\">Key Terms<\/h2>\n<div class=\"__UNKNOWN__\">\n<p><strong>Allele<\/strong>: Each of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome.<\/p>\n<p class=\"import-Normal\"><strong>Anthropocentrism<\/strong>: A way of thinking that assumes humans are the most important species and leads to interpreting the world always through a human lens. Species-centric science and thought.<\/p>\n<p class=\"import-Normal\"><strong>Cortex<\/strong>: The outside, or rough outer covering, of a rock. Usually the cortex is removed during the process of stone tool creation.<\/p>\n<p class=\"import-Normal\"><strong>Ethnocentric<\/strong>: Applying negative judgments to other cultures based on comparison to one\u2019s own.<\/p>\n<p class=\"import-Normal\"><strong>Exogenous DNA<\/strong>: DNA that originates from sources outside of the specimen you are trying to sequence.<\/p>\n<p class=\"import-Normal\"><strong>Flexed position<\/strong>: Fetal position, in which the legs are drawn up to the middle of the body and the arms are drawn toward the body centre. Intentional burials are often found in the flexed body position.<\/p>\n<p class=\"import-Normal\"><strong>Foraminifera<\/strong>: Microscopic single-celled organisms with a shell that are common in all marine environments. The fossil record of foraminifera extends back well over 500 million years.<\/p>\n<p class=\"import-Normal\"><strong>Glaciation<\/strong>: A glacial period, or time when a large portion of the world is covered by glaciers and ice sheets.<\/p>\n<p class=\"import-Normal\"><strong>Globular<\/strong>: Round-shaped, like a globe.<\/p>\n<p class=\"import-Normal\"><strong>Grave goods<\/strong>: Items included with a body at burial. Items may signify occupation or hobbies, social status, or level of importance in the community, or they may be items believed necessary for the afterlife.<\/p>\n<p class=\"import-Normal\"><strong>Haft<\/strong>: A handle. Also used as a verb\u2014to attach a handle to an item, such as a stone tool.<\/p>\n<p class=\"import-Normal\"><strong>Infraorbital foramina<\/strong>: Small holes on the maxilla bone of the face that allows nerves and blood to reach the skin.<\/p>\n<p class=\"import-Normal\"><strong>Insular dwarfing<\/strong>: A form of dwarfism that occurs when a limited geographic region, such as an island, causes a large-bodied animal to be selected for a smaller body size.<\/p>\n<p class=\"import-Normal\"><strong>Interglacial<\/strong>: A warmer period between two glacial time periods.<\/p>\n<p class=\"import-Normal\"><strong>Levallois technique<\/strong>: A distinctive technique of stone tool manufacturing used by Archaic <em>Homo sapiens<\/em>, including Neanderthals. The technique involves the preparation of a core and striking edges off in a regular fashion around the core. Then a series of similarly sized pieces can be removed, which can then be turned into different tools.<\/p>\n<p class=\"import-Normal\"><strong>Midfacial prognathism<\/strong>: A forward projection of the nose or the middle facial region. Usually associated with Neanderthals.<\/p>\n<p class=\"import-Normal\"><strong>Mousterian tools<\/strong>: The stone tool industry of Neanderthals and their contemporaries in Africa and Western Asia. Mousterian tools are known for a diverse set of flake tools, which is different from the large bifacial tools of the Acheulean industry.<\/p>\n<p class=\"import-Normal\"><strong>Nasal aperture<\/strong>: The opening for the nose visible on a skull. Often pear- or heart-shaped.<\/p>\n<p class=\"import-Normal\"><strong>Occipital bun<\/strong>: A prominent bulge or projection on the back of the skull, specifically the occipital bone. This is a feature present only on Neanderthal skulls.<\/p>\n<p class=\"import-Normal\"><strong>Ochre<\/strong>: A natural clay pigment mixed with ferric oxide and clay and sand. Ranges in colour from brown to red to orange.<\/p>\n<p class=\"import-Normal\"><strong>Retracted face<\/strong>: A face that is flatter.<\/p>\n<p class=\"import-Normal\"><strong>Retromolar gap<\/strong>: A space behind the last molar and the end of the jaw. This is a feature present only on Neanderthals. It also occurs through cultural modification in modern humans who have had their third molars, or wisdom teeth, removed.<\/p>\n<h2 class=\"import-Normal\">For Further Exploration<\/h2>\n<p><a href=\"https:\/\/www.amnh.org\/exhibitions\/permanent-exhibitions\/anne-and-bernard-spitzer-hall-of-human-origins\" target=\"_blank\">Anne and Bernard Spitzer Hall of Human Origins<\/a>\u2014American Museum of Natural History.<\/p>\n<p>\u201cDawn of Humanity,\u201d PBS documentary, 2015<\/p>\n<p><a href=\"https:\/\/www.ted.com\/talks\/svante_paeaebo_dna_clues_to_our_inner_neanderthal?language=en\" target=\"_blank\">\u201cDNA Clues to Our Inner Neanderthal,\u201d<\/a> TED Talk by Svante P\u00e4\u00e4bo, 2011.<\/p>\n<p>\u201cThe Dirt\u201d Podcast, Episode 30, <a href=\"https:\/\/thedirtpod.com\/episodes\/\/episode-30-the-human-family-tree-shrub-crabgrass-tumbleweed-part-3\" target=\"_blank\">\u201cThe Human Family Tree (Shrub? Crabgrass? Tumbleweed?), Part 3: Very Humany Indeed\u201d<\/a>.<\/p>\n<p class=\"import-Normal\"><a href=\"https:\/\/www.efossils.org\/page\/games-and-activities\" target=\"_blank\">eFossil Games and Activities<\/a><\/p>\n<p>Frank, Rebecca. 2021. \u201cThe Genus Homo.\u201d In <a href=\"https:\/\/explorations.americananthro.org\/index.php\/lab-and-activities-manual\/\" target=\"_blank\"><em>Explorations: Lab and Activity Manual, <\/em><\/a>edited by Beth Shook, Katie Nelson, Kelsie Aguilera, and Lara Braff. Arlington, VA: American Anthropological Association.<\/p>\n<p><a href=\"https:\/\/humanorigins.si.edu\/research\/asian-research-projects\/hobbits-flores-indonesia.\" target=\"_blank\">Hobbits on Flores, Indonesia<\/a> - Smithsonian Human Origins.<\/p>\n<p><a href=\"https:\/\/evolution.berkeley.edu\/evo-news\/lumping-or-splitting-in-the-fossil-record\/\" target=\"_blank\">Lumping or Splitting in the Fossil Record<\/a> - UC Berkeley Understanding Evolution.<\/p>\n<p><a href=\"https:\/\/www.eva.mpg.de\/genetics\/neandertals-and-more\/overview\/\" target=\"_blank\">Neandertals and More<\/a>\u00a0- Max Planck Institute for Evolutionary Anthropology.<\/p>\n<p><a href=\"https:\/\/www.sapiens.org\/biology\/neanderthal-anatomy\/?fbclid=IwAR2Bcff1GVkTLnbCR58JAWiJzkk-Ell7zL0FUddf1HNAX6RDAZxbqh1zWoI\" target=\"_blank\">Neanderthals: Body of Evidence<\/a> - SAPIENS.<\/p>\n<p>Perash, Rose L., and Kristen A. Broehl. 2021. \u201cHominin Review: Evolutionary Trends.\u201d In <a href=\"https:\/\/explorations.americananthro.org\/index.php\/lab-and-activities-manual\/.\" target=\"_blank\"><em>Explorations: Lab and Activity Manual<\/em><\/a>, edited by Beth Shook, Katie Nelson, Kelsie Aguilera, and Lara Braff. Arlington, VA: American Anthropological Association.<\/p>\n<p>Perkl, Bradley. \u201cBrain, Language, Lithics.\u201d In <a href=\"https:\/\/explorations.americananthro.org\/index.php\/lab-and-activities-manual\/.\" target=\"_blank\"><em>Explorations: Lab and Activity Manual<\/em><\/a>, edited by<em>.<\/em> Beth Shook, Katie Nelson, Kelsie Aguilera, and Lara Braff. CC BY-NC. Arlington, VA: American Anthropological Association.<\/p>\n<p><a href=\"https:\/\/humanorigins.si.edu\/evidence\/human-fossils\/shanidar-3-neanderthal-skeleton\" target=\"_blank\">Shanidar 3 - Neanderthal Skeleton<\/a> - Smithsonian Human Origins.<\/p>\n<p><a href=\"https:\/\/humanorigins.si.edu\/evidence\/human-fossils\/species\" target=\"_blank\">Species<\/a> - Smithsonian Human Origins.<\/p>\n<p><a href=\"https:\/\/www.facebook.com\/smithsonian.humanorigins\/\" target=\"_blank\">Smithsonian Human Origins Program Facebook page<\/a> (@smithsonian.humanorigins).<\/p>\n<p><a href=\"https:\/\/www.smithsonianmag.com\/science-nature\/bringing-human-evolution-life-180951155\/\" target=\"_blank\">Paleoartist Brings Human Evolution to Life<\/a> - Elisabeth Dayn\u00e9s.<\/p>\n<h2 class=\"import-Normal\">References<\/h2>\n<p>Ackermann, Rebecca R., Matthew L. Arnold, et al. \u201cHybridization in Human Evolution: Insights from Other Organisms.\u201d Evolutionary Anthropology 28, no. 4 (July 2019): 189\u2013209. <a href=\"https:\/\/doi.org\/10.1002\/evan.21787\" target=\"_blank\">https:\/\/doi.org\/10.1002\/evan.21787<\/a>. <a href=\"https:\/\/pmc.ncbi.nlm.nih.gov\/articles\/PMC6980311\/\" target=\"_blank\">https:\/\/pmc.ncbi.nlm.nih.gov\/articles\/PMC6980311\/<\/a><\/p>\n<p class=\"import-Normal\">Adler, Daniel S., Timothy J. Prindiville, and Nicholas J. Conard. 2003. \u201cPatterns of Spatial Organization and Land Use During the Eemian Interglacial in the Rhineland: New Data from Wallertheim, Germany.\u201d Eurasian Prehistory 1(2): 25\u201378.<\/p>\n<p>Ahlquist, K. D., Mayra M. 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In <\/em><a class=\"rId8\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\"><em>Explorations: An Open Invitation to Biological Anthropology, first edition<\/em><\/a><em>, edited by Beth Shook, Katie Nelson, Kelsie Aguilera, and Lara Braff, which is licensed under <\/em><a class=\"rId9\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\" target=\"_blank\"><em>CC BY-NC 4.0<\/em><\/a><em>. <\/em><\/p>\n<div class=\"textbox textbox--learning-objectives\">\n<header class=\"textbox__header\">\n<h2 class=\"textbox__title\">Learning Objectives<\/h2>\n<\/header>\n<div class=\"textbox__content\">\n<ul>\n<li class=\"import-Normal\">Identify the main groupings of Archaic <em>Homo sapiens<\/em>, such as Neanderthals.<\/li>\n<li class=\"import-Normal\">Explain how shifting environmental conditions required flexibility of adaptations, both anatomically and behaviourally.<\/li>\n<li class=\"import-Normal\">Describe the unique anatomical and cultural characteristics of Archaic <em>Homo sapiens, <\/em>including Neanderthals, in contrast to other hominins.<\/li>\n<li class=\"import-Normal\">Articulate how Middle Pleistocene hominin fossils fit into evolutionary trends including cranial capacity (brain size) development, cultural innovations, and migration patterns.<\/li>\n<li class=\"import-Normal\">Identify the shared traits, regional variations, and local adaptations among Archaic <em>Homo sapiens.<\/em><\/li>\n<li class=\"import-Normal\">Detail the increased complexity and debates surrounding the classification of hominins in light of transitional species, species admixture, etc.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<h2 class=\"import-Normal\">Breaking the Stigma of the \"Caveman\"<\/h2>\n<p class=\"import-Normal\">What do you think of when you hear the word \u201ccaveman\u201d? Perhaps you imagine a character from a film such as <em>The Croods<\/em>, <em>Tarzan<\/em>, and <em>Encino Man<\/em> or from the cartoon <em>The Flintstones<\/em>. Maybe you picture the tennis-playing, therapy-going hairy Neanderthals from Geico Insurance commercials. Or perhaps you imagine characters from <em>The Far Side<\/em> or <em>B.C.<\/em> comics. Whichever you picture, the character in your mind is likely stooped over with a heavy brow, tangled long locks and other body hair, and clothed in animal skins, if anything. They might be holding a club with a confused look on their face, standing at the entrance to a cave or dragging an animal carcass to a fire for their next meal (see Figure 12.1). You might have even signed up to take this course because of what you knew\u2014or expected to learn\u2014about \u201ccavemen.\u201d<\/p>\n<figure style=\"width: 163px\" class=\"wp-caption alignleft\"><img src=\"https:\/\/cdn.pixabay.com\/photo\/2013\/07\/13\/12\/36\/caveman-159964_1280.png\" alt=\"Free caveman beard man vector\" width=\"163\" height=\"317\" \/><figcaption class=\"wp-caption-text\">Figure 12.1:\u00a0Cartoon illustration of a prehistoric \u201ccaveman\u201d, commonly used as a visual representation of early humans in the Stone Age. Credit: <em data-start=\"261\" data-end=\"293\">Caveman, Beard, Man, Primitive<\/em>\u00a0free to use under the Pixabay <a href=\"https:\/\/pixabay.com\/service\/license-summary\/\" target=\"_blank\">Content License.<\/a><\/figcaption><\/figure>\n<p class=\"import-Normal\">These images have long been the stigma and expectation about our ancestors at the transition to modern <em>Homo sapiens<\/em>. Tracing back to works as early as Carl Linnaeus, scientists once propagated and advanced this imagery, creating a clear picture in the minds of early scholars that informed the general public, even through today, that Archaic <em>Homo sapiens<\/em>, \u201ccavemen,\u201d were somehow fundamentally different and much less intelligent than we are now. Unfortunately, this view is overly simplistic, misleading, and incorrect. Understanding what Archaic <em>Homo sapiens<\/em> were actually like requires a much more complex and nuanced picture, one that comes into sharper focus as continuing research uncovers more about the lives of our not-too-distant (and not-too-different) ancestors.<\/p>\n<p class=\"import-Normal\">The first characterizations of Archaic <em>Homo sapiens<\/em> were formed from limited fossil evidence in a time when <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1582\">ethnocentric<\/a><\/strong> and species-centric perspectives (<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1583\">anthropocentrism<\/a><\/strong>) were more widely accepted and entrenched in both society and science. Today, scientists are working from a more complete fossil record from three continents (Africa, Asia, and Europe), and genetic evidence informs their analyses and conclusions. The existence of Archaic <em>Homo sapiens<\/em> marks an exciting point in our lineage\u2014a point at which many modern traits had emerged and key refinements were on the horizon. Anatomically, humans today are not that much different from Archaic <em>Homo sapiens<\/em>.<\/p>\n<h2><\/h2>\n<h2 class=\"import-Normal\">The Changing Environment<\/h2>\n<p class=\"import-Normal\">While modern climate change is of critical concern today due to its cause (human activity) and pace (unprecedentedly rapid), the existence of global climate change itself is not a recent phenomenon. The focus of this chapter, the Middle Pleistocene (roughly between 780 kya and 125 kya), is the time period in which Archaic <em>Homo sapiens <\/em>appears in the fossil record\u2014a time that witnessed some of the most drastic climatic changes in human existence. During this time period, there were 15 major and 50 minor glacial events in Europe, alone.<\/p>\n<p class=\"import-Normal\">What exactly is <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1635\">glaciation<\/a><\/strong>? When scientists talk about glacial events, they are referring to the climate being in an ice age. This means that the ocean levels were much lower than today, because much of the earth\u2019s water was tied up in large glaciers or ice sheets. Additionally, the average temperature would have been much cooler, which would have better supported an Arctic or tundra-adapted plant-and-animal ecosystem in northern latitudes. The most interesting and relevant features of Middle Pleistocene glacial events are the sheer number of them and their repeated bouts: this era alternated between glacial periods and warmer periods, known as<strong> interglacials<\/strong>. In other words, the planet wasn\u2019t in an ice age the whole time.<\/p>\n<p class=\"import-Normal\">You can see the dramatic and increasing fluctuations in temperature, recorded through <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_906\">foraminifera<\/a><\/strong>, in Figure 12.2. The distance between highs and lows demonstrates the severity of temperature shifts. Much as the Richter scale represents more intense earthquakes with more dramatic peaks, so too does this chart, which uses dramatic peaks to demonstrate intense temperature swings.<\/p>\n<figure id=\"attachment_346-2\" aria-describedby=\"caption-attachment-346-2\" style=\"width: 1753px\" class=\"wp-caption alignnone\"><img class=\"size-full wp-image-329\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/All_palaeotemps.png\" alt=\"The graph shows changes in Earth\u2019s temperature for the last 540 My.\" width=\"1753\" height=\"565\" \/><figcaption id=\"caption-attachment-346-2\" class=\"wp-caption-text\">Figure 12.2: The Geologic Timescale and corresponding temperature shifts. Wide and rapid shifts took place during the Pleistocene (the second box from the right). More dramatic fluctuations depict greater severity of temperature shift. The Eocene, Pliocene, and Holocene epochs had more stable temperatures. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:All_palaeotemps.png\" target=\"_blank\">All paleotemps<\/a> by Glen Fergus is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Glacial periods are defined by Earth\u2019s average temperature being lower. Worldwide, temperatures are reduced, with cold areas becoming even colder. Huge portions of the landscape may have become inaccessible during glacial events due to the formation of glaciers and massive ice sheets. In Europe, the Scandinavian continental glacier covered what is today Ireland, England, Sweden, Norway, Denmark, and some of continental Europe. Plant and animal communities shifted to lower latitudes along the periphery of ice sheets. Additionally, some new land was opened during glacials. Evaporation with little runoff reduced sea levels by as much as almost 150 metres, shifting coastlines outward by in some instances as much as almost 100 kilometres. Additionally, land became exposed that connected what were previously unconnected continents such as Africa into Yemen at the Gulf of Aden.<\/p>\n<p class=\"import-Normal\">Glacial periods also affected equatorial regions and other regions that are today thought of as warmer or at least more temperate parts of the globe, including Africa. While these areas were not covered with glaciers, increased global glaciation resulted in lower sea levels and expanded coastlines. Cooler temperatures were accompanied by the drying of the climate, which caused significantly reduced rainfall, increased aridity, and the expansion of deserts. It is an interesting question to consider whether the same plants and animals that lived in these regions prior to the ice ages would be able to survive and thrive in this new climate. Plant and animal communities shifted in response to the changing climate, whenever possible.<\/p>\n<h2 class=\"import-Normal\">Surviving During the Middle Pleistocene<\/h2>\n<p class=\"import-Normal\">Rather than a single selective force, the Middle Pleistocene was marked by periods of fluctuation, not just cold periods. Interglacials interrupted glaciations, reversing trends in sea level, coastline, temperature, precipitation, and aridity, as well as glacier size and location. Interglacials are marked by increased rainfall and a higher temperature, which causes built-up ice in glaciers to melt. This leads to glacial retreat, which is the shrinking of glaciers and the movement of the glaciers back toward the poles, as we\u2019ve seen in our lifetime. During interglacials, sea levels increase, flooding some previously exposed coastlines and continental connections. In addition, plant and animal communities shift accordingly, often finding more temperate climates to the north and less arid and more humid climates in the tropics (Van Andel and Tzedakis 1996).<\/p>\n<p class=\"import-Normal\">Scientists have found that the Olorgesailie region in southern Kenya was at various times in the Middle Pleistocene a deep lake, a drought-dried lakebed with an area criss-crossed by small streams, and a grassland. While various animal species would have moved in and out of the area as the climate shifted, some animal species went extinct, and new, often related, species took up residence. The trend, scientists noted, was that animals with more specialized features went extinct and animals with more generalized features, such as animals we see today, survived in this changing climatic time period. For example, a zebra with specialized teeth for eating grass was ultimately replaced by a zebra that could eat both grass and other types of vegetation. If this small, localized example shows such a dramatic change in terms of the environment and the plant and animal biocommunities, what would have been the impact on humans?<\/p>\n<p class=\"import-Normal\">There is no way humans could have escaped the effects of Middle Pleistocene climate change, no matter what region of the world they were living in. As noted earlier, and as evidenced by what was seen in the other biotic communities, humans would have faced changing food sources as previous sources of food may have gone extinct or moved to a different latitude. Depending on where they were living, fresh water may have been limited. Durial glacials, lower sea levels would have given humans more land to live on, while the interglacials would have reduced the available land through the increase in rainfall and associated sea level rise. Dry land connections between the continents would have made movement from one continent to another by foot easier at times than today, although these passageways were not consistently available through the Middle Pleistocene due to the glacial\/interglacial cycle. Finally, as evidenced by the Olorgesailie region in Kenya, during the Middle Pleistocene animal species that were overly specialized to one particular type of environment were less likely to survive when compared to their more generalized counterparts. Evidence suggests that this same pattern may have held true for Archaic <em>Homo sapiens<\/em>, in terms of their ability to survive this dramatic period of climate change.<\/p>\n<h2 class=\"import-Normal\">Defining Characteristics of Archaic <em>Homo sapiens<\/em><\/h2>\n<p class=\"import-Normal\">Archaic <em>Homo sapiens<\/em> share our species name but are distinguished by the term \u201cArchaic\u201d as a way of recognizing both the long period of time between their appearance and ours, as well as the way in which human traits have continued to evolve over time\u2014making Archaic <em>Homo sapiens <\/em>look slightly different from us today, despite being considered the same species. Living throughout Africa, and the Middle East during the Middle Pleistocene, Archaic <em>Homo sapiens <\/em>are considered, in many ways, transitional between <em>Homo <\/em><em>erectus<\/em> and modern <em>Homo sapiens <\/em>(see Figure 12.3). Archaic<em> Homo sapiens<\/em> share the defining trait of an increased brain size of at least 1,100 cc and averaging 1,200 cc, although there are significant regional and temporal (time) variations. Because of these variations, scientists disagree on whether these fossils represent a single, variable species or multiple, closely related species (sometimes called <em>Homo antecessor<\/em>,<em> Homo bodoensis, Homo heidelbergensis<\/em>,<em> Homo georgicus<\/em>,<em> Homo neanderthalensis<\/em>, and <em>Homo rhodesiensis<\/em>).<\/p>\n<p class=\"import-Normal\">An active area of scholarship in the discipline involves reconciling the diversity of species from this time period and establishing the phylogenetic relationships between them. The term \u201cArchaic <em>Homo sapiens\u201d <\/em>can mean different things to different scholars within the discipline. The intent of this chapter is to provide an understanding of the diversity of this time period and provide data used to make interpretations from among the most likely possibilities. Although we recognize that some anthropologists split many of these fossils into separate species, until the issue is resolved at the discipline level, this chapter will rely on the widely used naming conventions that refer to many fossils from this time period as Archaic <em>Homo sapiens<\/em>. We will discuss these contemporaneous fossils as a unit<em>, <\/em>with the exception of a particularly unique population living in Europe and West Asia known as the Neanderthals, which we will examine separately.<\/p>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<caption>Figure 12.3: A comparison of Homo erectus, Archaic Homo sapiens, and anatomically modern Homo sapiens. This table compares key traits of the crania and postcrania that distinguish these three hominins. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-16\/\" target=\"_blank\">Homo erectus, Archaic Homo sapiens, and anatomically modern Homo sapiens table (Figure 11.3)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Amanda Wolcott Paskey and AnnMarie Beasley Cisneros is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/caption>\n<thead>\n<tr style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Trait<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong><em>Homo <\/em><\/strong><strong><em>erectus<\/em><\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Archaic <\/strong><strong><em>Homo sapiens <\/em><\/strong><strong>(including Neaderthals)<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Anatomically Modern <\/strong><strong><em>Homo sapiens<\/em><\/strong><\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Time<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1.8 mya\u2013200,000 ya<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">600,000\u201340,000 ya<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">315,000 ya\u2013today<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Brain size<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">900 cc<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1,200 cc (1,500 cc when including Neanderthals)<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1,400 cc<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Skull Shape<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Long and low,<\/p>\n<p class=\"import-Normal\">angular<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Intermediate<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Short and high, <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1643\">globular<\/a><\/strong><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Forehead<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Absent<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Emerging<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Present<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Nasal Region<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Projecting nasal bones (bridge of the nose), no midfacial prognathism<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Wider nasal aperture and some midfacial prognathism, particularly pronounced among Neanderthals<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Narrower nasal aperture, no midfacial prognathism<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Chin<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Absent<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Absent<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Present<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Other Facial Features<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Large brow ridge and large projecting face<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Intermediate<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Small brow ridge and<strong> retracted face<\/strong><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Other Skull Features<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Nuchal torus, sagittal keel, thick cranial bone<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Projecting occipital bone, often called occipital bun in Neanderthals; intermediate thickness of cranial bone<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Small bump on rear of skull, if anything; thin cranial bone<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dentition<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Large teeth, especially front teeth<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Slightly smaller teeth; front teeth still large;<\/p>\n<p class=\"import-Normal\">retromolar gap in Neanderthals<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Smaller teeth<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Postcranial Features<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Robust bones of skeleton<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Robust bones of skeleton<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">More gracile bones of skeleton<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<p class=\"import-Normal\">When comparing <em>Homo <\/em><em>erectus<\/em>, Archaic<em> Homo sapiens, <\/em>and anatomically modern <em>Homo sapiens<\/em>, one can see that Archaic<em> Homo sapiens<\/em> are intermediate in their physical form. For some features, this follows the trends first seen in <em>Homo <\/em><em>erectus<\/em> with other features having early, less developed forms of traits seen in modern <em>Homo sapiens<\/em>. For example, Archaic <em>Homo sapiens<\/em> trended toward less angular and higher skulls than <em>Homo <\/em><em>erectus<\/em><em>. <\/em>However, the archaic skulls were not as short and globular and had less developed foreheads compared to anatomically modern <em>Homo sapiens. <\/em>Archaic <em>Homo sapiens<\/em> had smaller brow ridges and a less-projecting face than <em>Homo <\/em><em>erectus<\/em> and slightly smaller teeth, although incisors and canines were often about as large as those of <em>Homo <\/em><em>erectus<\/em>. Archaic <em>Homo sapiens <\/em>also had a wider <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1638\">nasal aperture<\/a><\/strong>, or opening for the nose, and a forward-projecting midfacial region, which is later seen more fully developed among Neanderthals and is known as <strong>midfacial prognathism<\/strong>. The occipital bone often projected and the cranial bone was of intermediate thickness, somewhat reduced from <em>Homo <\/em><em>erectus<\/em> but not nearly as thin as that of anatomically modern <em>Homo sapiens. <\/em>The postcrania remained fairly robust. Identifying a set of features that is unique to Archaic<em> Homo sapiens<\/em> is a challenging task, due to both individual and geographic variation\u2014these developments were not all present to the same degree in all individuals. Neanderthals are the exception, as they had several unique traits that made them notably different from modern <em>Homo sapiens<\/em> as well as their closely related Archaic cousins.<\/p>\n<figure style=\"width: 299px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image10-4.png\" alt=\"Archaic Homo sapiens skull cast.\" width=\"299\" height=\"299\" \/><figcaption class=\"wp-caption-text\">Figure 12.4: \u201cBroken Hill Man,\u201d found at Kabwe in Zambia, shows common traits associated with archaic Homo sapiens in Africa, including a large brain, taller cranium, and Homo erectus-like features such as massive brow ridges, a large face, and thick cranial bones. Credit: <a href=\"https:\/\/boneclones.com\/product\/homo-heidelbergensis-skull-broken-hill-1-rhodesian-man-BH-004\" target=\"_blank\">Homo heidelbergensis Cranium Broken Hill 1 (Rhodesian Man)<\/a> by <a href=\"https:\/\/boneclones.com\/\" target=\"_blank\">\u00a9BoneClones<\/a> is used by permission and available here under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">The one thing that is clear about Archaic <em>Homo sapiens<\/em> is that, despite general features, there is a lot of regional variation, which is first seen in the different <em>Homo <\/em><em>erectus<\/em> specimens across Asia and Africa. While the general features of Archaic <em>Homo sapiens<\/em>, identified earlier, are present in the fossils of this time period, there are significant regional differences. The majority of this regional variation lies in the degree to which fossils have features more closely aligned with <em>Homo <\/em><em>erectus<\/em> or with anatomically modern <em>Homo sapiens<\/em>.<\/p>\n<figure style=\"width: 244px\" class=\"wp-caption alignright\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image7-5.png\" alt=\"Side view of the Dali cranium.\" width=\"244\" height=\"213\" \/><figcaption class=\"wp-caption-text\">Figure 12.5: Dali cranium, found at Dali, China, is representative of traits seen in archaic Homo sapiens in Asia, including large and robust features with heavy brow ridges like Homo erectus and a large cranial capacity intermediate between Homo erectus and anatomically modern Homo sapiens. Credit: Dali skull original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by <a href=\"https:\/\/marynelsonstudio.com\" target=\"_blank\">Mary Nelson<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p>To illustrate this point, we will examine three exemplary specimens, one from each of the three continents on which Archaic<em> Homo sapiens <\/em>lived. First, in Africa, a specimen from Broken Hill is one of several individuals found in the Kabwe lead mine in Zambia. It had a large brain (1,300 cc) and taller cranium as well as many <em>Homo erectus-<\/em>like skull features, including massive brow ridges, a large face, and thick cranial bones (Figure 12.4). Second, one partial crania from Dali, China, is representative of Archaic<em> Homo sapiens <\/em>in Asia, with large and robust features with heavy brow ridges, akin to what is seen in <em>Homo <\/em><em>erectus<\/em>, and a large cranial capacity intermediate between <em>Homo <\/em><em>erectus<\/em> and anatomically modern <em>Homo sapiens<\/em> (Figure 12.5). Third, an almost-complete skeleton was found in northern Spain at Atapuerca. Atapuerca 5 (Figure 12.6) has thick cranial bone, an enlarged cranial capacity, intermediate cranial height, and a more rounded cranium than seen previously. Additionally, Atapuerca 5 demonstrates features that foreshadow Neanderthals, including increased midfacial prognathism. After examining some of the fossils such as those from Kabwe, Dali, and Atapuerca, the transitional nature of Archaic<em> Homo sapiens <\/em>is clear: their features place them squarely between <em>Homo <\/em><em>erectus<\/em> and modern <em>Homo sapiens<\/em>.<\/p>\n<figure style=\"width: 293px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image13-4.png\" alt=\"Archaic Homo sapiens skull cast with mandible.\" width=\"293\" height=\"293\" \/><figcaption class=\"wp-caption-text\">Figure 12.6: Atapuerca 5 archaic Homo sapiens, found in northern Spain, is representative of traits seen in archaic Homo sapiens in Europe, including a thick cranial bone, an enlarged cranial capacity, intermediate cranial height, a more rounded cranium, and increased midfacial projection. Credit: <a href=\"https:\/\/boneclones.com\/product\/homo-heidelbergensis-skull-atapuerca-5-BH-022\" target=\"_blank\">Homo heidelbergensis Skull Atapuerca 5<\/a> by <a href=\"https:\/\/boneclones.com\/\" target=\"_blank\">\u00a9BoneClones<\/a> is used by permission and available here under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Due to the transitional nature of Archaic<em> Homo sapiens<\/em>, identifying the time period with which they are associated is problematic and complex. Generally, it is agreed that Archaic<em> Homo sapiens <\/em>lived between 600,000 and 200,000 years ago, with regional variation and overlap between <em>Homo <\/em><em>erectus<\/em> on the early end of the spectrum and modern <em>Homo sapiens <\/em>and Neanderthals on the latter end. The earliest-known Archaic<em> Homo sapiens <\/em>fossils tentatively date to about 600,000 years ago in Africa, to around 300,000 years ago in Asia, and to about 350,000 years ago in Europe (and potentially as early as 600,000 years ago). Determining the end point of Archaic<em> Homo sapiens <\/em>is also problematic since it largely depends upon when the next subspecies of <em>Homo sapiens <\/em>appears and the classification of highly intermediate specimens. For example, in Africa, the end of Archaic<em> Homo sapiens <\/em>is met with the appearance of modern <em>Homo sapiens<\/em>, while in Europe it is the appearance of Neanderthals that is traditionally seen as marking the transition from other Archaic<em> Homo sapiens. <\/em><\/p>\n<p class=\"import-Normal\">It is important to remember that this time period is represented by many branching relationships and assuming an evolutionary trajectory that follows a single linear path would not be correct. Even still, Archaic<em> Homo sapiens <\/em>mark an important chapter in the human lineage, connecting more ancestral forms, such as <em>Homo <\/em><em>erectus<\/em>, to modern <em>Homo sapiens<\/em>. During this period of climatic transition and fluctuation, Archaic <em>Homo sapiens<\/em> mirror the challenges of their environments. Showing increasing regional variation due to the need for local adaptation, there is no single archetype for this group; the defining characteristic seems to be variability.<\/p>\n<h2 class=\"import-Normal\">Neanderthals<\/h2>\n<p class=\"import-Normal\">One well-known population of Archaic <em>Homo sapiens <\/em>are the Neanderthals, named after the site where they were first discovered in the Neander Valley, or \u201cthal\u201d in German, located near Dusseldorf, Germany. Popularly known as the stereotypical \u201ccavemen\u201d examined at the outset of this chapter, recent research is upending long-held beliefs about this group of Archaics. Neanderthal behaviour was increasingly complex, far beyond what was exhibited by even other Archaic <em>Homo sapiens<\/em> discussed throughout this chapter. We implore you to forget the image of the iconic caveman and have an open mind when exploring the fossil evidence of the Neanderthals.<\/p>\n<p class=\"import-Normal\">It is important to understand why Neanderthals are separated from other Archaic <em>Homo sapiens<\/em>. Unlike the rest of Archaic <em>Homo sapiens<\/em>, Neanderthals are easily defined and identified in many ways. Evidence suggests the time period when Neanderthals lived was between 150,000 and 40,000 years ago. There is a clear geographic boundary of where Neanderthals lived: western Europe, the Middle East, and western Asia. No Neanderthal fossils have ever been discovered outside of this area, including Africa. This is a bit curious, as other Archaics seem to have adapted in Africa and then migrated elsewhere, but Neanderthals\u2019 regional association makes sense in light of the environment to which they were best adapted: namely, extreme cold weather. Additionally, Neanderthals have a unique and distinct cluster of physical characteristics. While a few aspects of Neanderthals are shared among some Archaic <em>Homo sapiens<\/em>, such as the types of tools, most Neanderthal anatomical and behavioural attributes are unique to them.<\/p>\n<p class=\"import-Normal\">Neanderthals lived during some of the coldest times during the last Ice Age and at far northern latitudes. This means Neanderthals were living very close to the glacial edge, rather than in a more temperate region of the globe like some of their Archaic <em>Homo sapiens<\/em> relatives. While able to survive in arctic conditions, most Neanderthal sites dating to the glacial periods were found farther away from the severe cold, in a steppe tundra-like environment, which would have been more hospitable to Neanderthals, and their food sources, both flora and fauna (Ashton 2002; Nicholson 2017; Richter 2006). Their range likely expanded and contracted along with European glacial events, moving into the Middle East during glacial events when Europe became even cooler, and when the animals they hunted would have moved for the same reason. During interglacials, when Europe warmed a bit, Neanderthals and their prey would have been able to move back into Western Europe. Clearly, the true hallmark of Neanderthals is their adaptation to an unstable environment, shifting between warm and cold, as the climate was in constant flux throughout their existence (Adler Et al. 2003; Boettger Et al. 2009).<\/p>\n<p class=\"import-Normal\">Many of the Neanderthals\u2019 defining physical features are more extreme and robust versions of traits seen in other Archaic<em> Homo sapiens<\/em>, clustered in this single population. Brain size, namely an enlargement of the cranial capacity, is one such trait. The average Neanderthal brain size is around 1,500 cc, and the range for Neanderthal brains can extend to upwards of 1,700 cc. The majority of the increase in the brain occurs in the occipital region, or the back part of the brain, resulting in a skull that has a large cranial capacity with a distinctly long and low shape that is slightly wider than previous forms at the far back of the skull. Modern humans have a brain size comparable to that of Neanderthals; however, our brain expansion occurred in the frontal region of the brain, not the back, as in Neanderthal brains. This difference is also the main reason why Neanderthals lack the vertical forehead that modern humans possess. They simply did not need an enlarged forehead, because their brain expansion occurred in the rear of their brain. Due to cranial expansion, the back of the Neanderthal skull is less angular (as compared to <em>Homo erectus<\/em>), but not as rounded as <em>Homo sapiens<\/em>, producing an elongated shape, akin to a football.<\/p>\n<p class=\"import-Normal\">Another feature that continues the trend noted in previous hominins is the enlargement of the nasal region, or the nose. Neanderthal noses are large and have a wide nasal aperture, which is the opening for the nose. While the nose is only made up of two bones, the nasals, the true size of the nose can be determined by looking at other facial features, including the nasal aperture, and the angle of the nasal and maxillary, or facial bones. In Neanderthals, these indicate a large, forward-projecting nose that appears to be pulled forward away from the rest of the face. This feature is further emphasized by the backward-sloping nature of the cheekbones, or the zygomatic arches. The unique shape and size of the Neanderthal nose is often characterized by the term <em>midfacial prognathism<\/em>\u2014a jutting out of the middle portion of the face, or nose. This is in sharp contrast to the prognathism exhibited by other hominins, who exhibited prognathism, or the jutting out, of their jaws.<\/p>\n<p class=\"import-Normal\">The teeth of the Neanderthals follow a similar pattern seen in the Archaic <em>Homo sapiens<\/em>, which is an overall reduction in size, especially as compared to the extremely large teeth seen in the genus <em>Australopithecus<\/em>. However, while the teeth continued to reduce, the jaw size did not keep pace, leaving Neanderthals with an oversized jaw for their teeth, and a gap between their final molar and the end of their jaw. This gap is called a <strong>retromolar gap<\/strong>.<\/p>\n<p class=\"import-Normal\">The projecting occipital bone present in other Archaic<em> Homo sapiens <\/em>is also more prominent in Neanderthals, extending the trend found in Archaics. Among Neanderthals, this projection of bone is easily identified by its bun shape on the back of the skull and is known as an <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1645\">occipital bun<\/a><\/strong>. This projection appears quite similar to a dinner roll in size and shape. Its purpose, if any, remains unknown.<\/p>\n<p class=\"import-Normal\">Continuing the Archaic<em> Homo sapiens <\/em>trend, Neanderthal brow ridges are prominent but somewhat smaller in size than those of <em>Homo <\/em><em>erectus<\/em> and earlier Archaic<em> Homo sapiens. <\/em>In Neanderthals, the brow ridges are also often slightly less arched than those of other Archaic<em> Homo sapiens<\/em>.<\/p>\n<p class=\"import-Normal\">In addition to extending traits present in Archaic<em> Homo sapiens, <\/em>Neanderthals possess several distinct traits. Neanderthal <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1646\">infraorbital foramina<\/a><\/strong>, the holes in the maxillae or cheek bones through which blood vessels pass, are notably enlarged compared to other hominins. The Neanderthal postcrania are also unique in that they demonstrate increased robusticity in terms of the thickness of bones and body proportions that show a barrel-shaped chest and short, stocky limbs, as well as increased musculature. These body portions are seen across the spectrum of Neanderthals\u2014in men, women, and children.<\/p>\n<p class=\"import-Normal\">Traditionally, many of the unique traits that Neanderthals possess were seen as adaptations to the extreme cold, dry environments in which they often lived and which exerted strong selective forces. For example, Bergmann\u2019s and Allen\u2019s Rules dictate that an increased body mass and short, stocky limbs are common in animals that live in cold conditions. Neanderthals were said to have matched the predictions of Bergmann\u2019s and Allen\u2019s Rules perfectly (Churchill 2006). In addition, the Neanderthal skull also exhibits adaptations to the cold. Neanderthals\u2019 large infraorbital foramina allow for larger blood vessels, increasing the volume of blood that is found closest to the skin, which helps to keep the skin warmer. Their enlarged noses resulted in longer nasal passages and mucus membranes that warmed and moistened cold air before it reached the lungs. The Neanderthals\u2019 larger nose has long been thought to have acted as a humidifier, easing physical exertion in their climate, although research on this particular trait continues to be studied and debated (Rae Et al. 2011).<\/p>\n<p class=\"import-Normal\">New research, however, seems to suggest that these unique skeletal adaptations might not have been strict adaptations to cold weather (Evteev Et al. 2017; Pearce Et al. 2013). For example, large brow ridges might have served as a way to shade the face from the sun. The increased occipital portion of the brain, some researchers state, was to support a larger visual system present in Neanderthals. This visual system would have given them increased light sensitivity, which would have been useful in higher latitudes that had dark winters. And, while recent modeling of nostril airflow on reconstructed Neanderthal specimens supports the notion that Neanderthals had extensive mucus membranes inside their noses, the data shows that modern <em>Homo sapiens<\/em> are superior to Neanderthals in our ability to use our noses as a way to warm and cool air. However, Neanderthals were able to snort air through their noses better than we can. Why is this important? When combined with the fact that Neanderthals tended to prefer a more temperate, tundra-like environment, and that other physical traits suggest that Neanderthals had huge bodies that needed massive amounts of calories to sustain them, the picture gets clearer. Massive amounts of energy would have been required to power a Neanderthal body, and anything that might have made them more calorically efficient would have been favoured. Efficient breathing, through larger noses into large lungs, meaning deeper breaths, would have been favoured. To further save energy expenditure, body sizes might have been sacrificed as well. These same types of adaptations are similar to ones seen in children today who are born in high altitudes, not cold climates. Figure 12.7 provides a summary of these unique features of the Neanderthal.<\/p>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<caption>Figure 12.7: Neanderthal distinguishing features. This table outlines key features associated with Neanderthals. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-16\/\" target=\"_blank\">Neanderthal distinguishing features table (Figure 11.6)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Amanda Wolcott Paskey and AnnMarie Beasley Cisneros is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/caption>\n<thead>\n<tr style=\"height: 21pt\">\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\" colspan=\"2\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Distinct Neanderthal Anatomical Features<\/strong><\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Brain Size<\/strong><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1,500 cc average<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Skull Shape<\/strong><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Long and low<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Brow Ridge Size<\/strong><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Large<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Nose Size<\/strong><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Large, with midfacial prognathism<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dentition<\/strong><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Reduced, but large jaw size, creating retromolar gap<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Occipital Region<\/strong><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Enlarged occipital region, occipital bun<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Other Unique Cranial Features<\/strong><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Large infraorbital foramina<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Postcranial Features<\/strong><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Short and stocky body, increased musculature, barrel-shaped chest<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<p class=\"import-Normal\">A classic example of a Neanderthal with all of the characteristics mentioned above is the nearly complete La Ferrassie 1 Neanderthal, from France. This is a male skeleton, with a brain size of around 1640cc, an extremely large nose and infraorbital foramina, brow ridges that are marked in size, and an overall robust skeleton (Figure 12.8).<\/p>\n<p>&nbsp;<\/p>\n<figure style=\"width: 390px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image1-4.png\" alt=\"A reproduction of a complete Neanderthal skeleton.\" width=\"390\" height=\"689\" \/><figcaption class=\"wp-caption-text\">Figure 12.8: La Ferrassie 1 Neanderthal is representative of many classic Neanderthal features, including a large brain, large nose, large infraorbital foramina, large brow ridges, and robust postcrania. Credit: <a href=\"https:\/\/boneclones.com\/product\/neanderthal-skeleton-articulated-SC-019-A\" target=\"_blank\">Neanderthal Skeleton Articulated<\/a> by <a href=\"https:\/\/boneclones.com\/\" target=\"_blank\">\u00a9BoneClones<\/a> is used by permission and available here under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<h3 class=\"import-Normal\"><strong>Neanderthal Culture: Tool Making and Use<\/strong><\/h3>\n<p class=\"import-Normal\">One key Neanderthal adaptation was their cultural innovations, which are an important way that hominins adapt to their environment. As you recall, <em>Homo erectus<\/em>'s tools, Acheulean handaxes, represented an increase in complexity over Oldowan tools, allowing more efficient removal of meat and possibly calculated scavenging. In contrast, Neanderthal tools mark a significant innovation in tool-making technique and use with <strong>Mousterian tools<\/strong> (named after the Le Moustier site in southwest France). These tools were significantly smaller, thinner, and lighter than Acheulean handaxes and formed a true toolkit. The materials used for Mousterian tools were of higher quality, which allowed for both more precise toolmaking and tool reworking when the tools broke or dulled after frequent reuse. The use of higher-quality materials is also indicative of required forethought and planning to acquire them for tool manufacture. It has been suggested that the Neanderthals, unlike <em>Homo <\/em><em>erectus<\/em>, saved and reused their tools, rather than making new ones each time a tool was needed.<\/p>\n<figure style=\"width: 290px\" class=\"wp-caption alignright\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image3-4.png\" alt=\"Large flakes separated from the core.\" width=\"290\" height=\"159\" \/><figcaption class=\"wp-caption-text\">Figure 12.9: The Levallois technique is used to create Mousterian tools. The multistep process involves preparing the core in a specific way to yield flakes that can be used as tools. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Nucl%C3%A9us_Levallois_La-Parrilla.png\" target=\"_blank\">Nucl\u00e9us Levallois La-Parrilla<\/a> by Jos\u00e9-Manuel Benito \u00c1lvarez is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.5\/legalcode\" target=\"_blank\">CC BY-SA 2.5 License<\/a>..<\/figcaption><\/figure>\n<p>Mousterian tools are constructed in a very unique manner, utilizing the <strong>Levallois technique<\/strong> (Figure 12.9), named after the first finds of tools made with this technique, which were discovered in the Levallois-Perret suburb of Paris, France. The Levallois technique is a multistep process that requires preparing the core, or raw material, in a specific way that will yield flakes that are roughly uniform in dimension. The flakes are then turned into individual tools. The preparation of the core is akin to peeling a potato or carrot with a vegetable peeler\u2014when peeling vegetables, you want to remove the skin in long, regular strokes, so that you are taking off the same amount of the vegetable all the way around. In the same way, the Levallois technique requires removing all edges of the <strong>cortex<\/strong>, or outside surface of the raw material, in a circle before removing the lid. The flakes, which will eventually be turned into the individual tools, can then be removed from the core. The potential yield of tools from one core would be many, as seen in Figure 12.10, compared to all previous tool-making processes, in which one core yielded a single tool. This manufacturing process might be considered the ultimate zero-waste tool-making technique (Delpiano Et al. 2018).<\/p>\n<figure style=\"width: 589px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image19-4.png\" alt=\"Levallois core and flakes that are gray in color and various shapes and sizes.\" width=\"589\" height=\"470\" \/><figcaption class=\"wp-caption-text\">Figure 12.10: Levallois core and flakes for tool production. Using this technique, one core is used to produce many flakes, each of which can be turned into a tool. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:NHM_-_Levalloiskern.jpg\" target=\"_blank\">NHM - Levalloiskern<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Xenophon\" target=\"_blank\">Wolfgang Sauber<\/a> (user: Xenophon) is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\" target=\"_blank\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">It is suggested that Neanderthal tools were used for a variety of purposes, including cutting, butchering, woodworking or antler working, and hide working. Additionally, because the Mousterian tools were lighter than previous stone tools, Neanderthals could <strong>haft<\/strong>, or attach the tool onto a handle, as the stone would not have been too heavy (Degano Et al. 2019). Neanderthals attached small stone blades onto short wood or antler handles to make knives or other small weapons, as well as attached larger blades onto longer shafts to make spears. New research examining tar-covered stones and black lumps at several Neanderthal sites in Europe suggests that Neanderthals may have been making tar by distilling it from birch tree bark, which could have been used to glue the stone tool onto its handle. If Neanderthals were, in fact, manufacturing tar to act as glue, this would predate modern humans in Africa using tree resin or similar adhesives by nearly 100,000 years.<\/p>\n<p class=\"import-Normal\">Evidence shows that raw materials used by Neanderthals came from distances as far away as 100 km. This could indicate a variety of things regarding Neanderthal behaviour, including a limited trade network with other Neanderthal groups or simply a large area scoured by Neanderthals when collecting raw materials. While research on specific applications continues, it should be clear from this brief discussion that Neanderthal tool manufacturing was much more complex than previous tool-making efforts, requiring technical expertise, patience, and skills beyond toolmaking to carry out.<\/p>\n<h3 class=\"import-Normal\"><strong>Neanderthal Culture: Hunting and Diet<\/strong><\/h3>\n<p class=\"import-Normal\">With their more sophisticated suite of tools and robust muscular bodies, Neanderthals were better armed for hunting than previous hominins. The animal remains in Neanderthal sites show that, unlike earlier Archaic <em>Homo sapiens<\/em>, Neanderthals were very effective hunters who were able to kill their own prey, rather than relying on scavenging. Though more refined than the tools of earlier hominins, the Neanderthal spear was not the kind of weapon that would have been thrown; rather, it would have been used in a jabbing fashion (Churchill 1998; Kortlandt 2002). This may have required Neanderthals to hunt in groups rather than individually and made it necessary to approach their prey quite closely (Gaudzinski-Windheuser Et al. 2018). Remember, the animals living with Neanderthals were very large-bodied due to their adaptations to cold weather; this would have included species of deer, horses, and bovids (relatives of the cow).<\/p>\n<p class=\"import-Normal\">Isotopes from Neanderthal bones show that meat was a significant component of their diet, similar to that seen in carnivores like wolves (Bocherens Et al. 1999; Jaouen Et al. 2019; Richards Et al. 2000). In addition to large prey, their diet included ibex, seals, rabbits, and pigeons. Though red meat was a critical component of the Neanderthal diet, evidence shows that at times they also ate limpets, mussels, and pine nuts. Tartar examined from Neanderthal teeth in Iraq and Belgium reveal that they also ate plant material including wheat, barley, date palms, and tubers, first cooking them to make them palatable (Henry Et al. 2010). While Neanderthals\u2019 diet varied according to the specific environment in which they lived, meat comprised up to 80% of their diet (Wi\u1e9ein Et al. 2015).<\/p>\n<h3 class=\"import-Normal\"><strong>Neanderthal Culture: Caring for the Injured and Sick<\/strong><\/h3>\n<p class=\"import-Normal\">While the close-range style of hunting used by Neanderthals was effective, it also had some major consequences. Many Neanderthal skeletons have been found with significant injuries, which could have caused paralysis or severely limited their mobility. Many of the injuries are to the head, neck, or upper body. Thomas Berger and Erik Trinkaus (1995) conducted a statistical comparative analysis of Neanderthal injuries compared to those recorded in modern-day workers\u2019 compensation reports and found that the closest match was between Neanderthal injuries and those of rodeo workers. Rodeo professionals have a high rate of head and neck injuries that are similar to the Neanderthals\u2019 injuries. What do Neanderthals and rodeo workers have in common? They were both getting very close to large, strong animals, and at times their encounters went awry.<\/p>\n<p class=\"import-Normal\">The extensive injuries sustained by Neanderthals are evident in many fossil remains. Shanidar 1 (Figure 12.11), an adult male found at the Shanidar site in northern Iraq and dating to 45,000 ya, has a lifetime of injuries recorded in his bones (Stewart 1977). Shanidar 1 sustained\u2014and healed from\u2014an injury to the face that would have likely caused blindness. His lower right arm was missing and the right humerus shows severe atrophy, likely due to disuse. This pattern has been interpreted to indicate a substantial injury that required or otherwise resulted in amputation or wasting away of the lower arm. Additionally, Shanidar 1 suffered from bony growths in the inner ear that would have significantly impaired his hearing and severe arthritis in the feet. He also exhibited extensive anterior tooth wear, matching the pattern of wear found among modern populations who use their teeth as a tool. Rather than an anomaly, the type of injuries evident in Shanidar 1 are similar to those found in many other Neanderthal fossils, revealing injuries likely sustained from hunting large mammals as well as demonstrating a long life of physical activity.<\/p>\n<p>&nbsp;<\/p>\n<p><img class=\"aligncenter\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image11-4.png\" alt=\"Neaderthal skull.\" width=\"329\" height=\"329\" \/><\/p>\n<figure style=\"width: 330px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image5-4.png\" alt=\"Neaderthal right and left humerus. The right humerus is withered looking.\" width=\"330\" height=\"330\" \/><figcaption class=\"wp-caption-text\">Figure 12.11a-b: a. The Shanidar 1 skull shows an injury to the face that would likely have caused blindness. b. The Shanidar 1 right humerus (on the left side of the image) shows severe atrophy, likely due to disuse. Credit: a. <a href=\"https:\/\/boneclones.com\/product\/shanidar-1-skull-BH-050\" target=\"_blank\">Homo neanderthalensis Shanidar 1 Skull<\/a> by <a href=\"https:\/\/boneclones.com\/\" target=\"_blank\">\u00a9BoneClones<\/a> is used by permission and available here under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>. b. <a href=\"https:\/\/humanorigins.si.edu\/evidence\/human-fossils\/fossils\/shanidar-1\" target=\"_blank\">Shanidar 1<\/a> by Chip Clark, <a href=\"https:\/\/www.si.edu\/\" target=\"_blank\">Smithsonian Institution<\/a> [exhibit: <a href=\"https:\/\/humanorigins.si.edu\/research\" target=\"_blank\">Human Evolution <\/a>Evidence, Human Fossils, Species, Homo neanderthalensis] <a href=\"https:\/\/www.si.edu\/termsofuse\" target=\"_blank\">is used for educational and non-commercial purposes as outlined by the Smithsonian.<\/a><\/figcaption><\/figure>\n<p class=\"import-Normal\">The pattern of injuries is as significant as the fact that Shanidar 1 and other injured Neanderthals show evidence of having <em>survived<\/em> their severe injuries. One of the earliest-known Neanderthal discoveries\u2014the one on whom misinformed analysis shaped the stereotype of the species for nearly a century\u2014is the La Chapelle-aux-Saints Neanderthal (Trinkaus 1985). The La Chapelle Neanderthal had a damaged eye orbit that likely caused blindness and suffered arthritis of the spine (Dawson and Trinkaus 1997). He had also lost most of his teeth, many of which he had lived without for so long that the mandibular and maxillary bones were partially reabsorbed due to lack of use. The La Chapelle Neanderthal was also thought to be at least in his mid-forties at death, an old age for the rough life of the Late Pleistocene\u2014giving rise to his nickname, \u201cthe Old Man.\u201d To have survived so long with so many injuries that obviously precluded successful large game hunting, he must have been taken care of by others. Such caretaking behaviour is also evident in the survival of other seriously injured Neanderthals, such as Shanidar 1. Long thought to be a hallmark modern human characteristic, taking care of the injured and elderly, for example preparing or pre-chewing food for those without teeth, indicates strong social ties among Neanderthals.<\/p>\n<h3 class=\"import-Normal\"><strong>Neanderthal Culture: Ritual Life<\/strong><\/h3>\n<p class=\"import-Normal\">Such care practices may have been expressed upon death as well. Nearly complete Neanderthal skeletons are not uncommon in the fossil record, and most are well preserved within apparently deliberate burials that involve deep graves and bodies found in specific, often fetal or <strong>flexed positions<\/strong> (Harrold 1980)<strong>.<\/strong> Discoveries of pollen in a grave at the Shanidar site in the 1960s led scientists to think that perhaps Neanderthals had placed flowering plants in the grave, an indication of ritual ceremony or spirituality so common in modern humans. But more recent investigations have raised some doubt about this conclusion (Pomeroy Et al. 2020). The pollen may have been brought in by burrowing rodents. Claims of <strong>grave goods<\/strong> or other ornamentation in burials are similarly debated, although possible.<\/p>\n<p class=\"import-Normal\">Some tantalizing evidence for symbolism, and debatably, ritual, is the frequent occurrence of natural pigments, such as <strong>ochre<\/strong> (red) and manganese dioxide (black) in Neanderthal sites that could have been used for art. However, the actual uses of pigments are unclear, as there is very little evidence of art or paintings in Mousterian sites. One exception may be the recent discovery in Spain of a perforated shell that appears to be painted with an orange pigment, which may be evidence of Neanderthal art and jewelry. However, many pigments also have properties that make them good emulsifiers in adhesive (like for attaching a stone tool to a wooden handle) or useful in tanning hides. So the presence of pigment may or may not be associated with symbolic thought; however, it definitely does show a technological sophistication beyond that of earlier Archaic hominins.<\/p>\n<div class=\"textbox shaded\" style=\"background: var(--lightblue)\">\n<h2>Dig Deeper: Evidence of Endocannibalism Among the Neanderthals<\/h2>\n<p>Krapina, a Neanderthal site in Croatia, has recently sparked new archeological discourse as many investigations upon fossilized remains show evidence of post-mortem modifications and manipulations of limbs and bones through the use of tools (Rougier Et al., 2016). These findings provide compelling evidence of Neanderthals engaging in cannibalism as part of their post-mortem practices. Additionally, these uncovered remains were found to have died of natural causes as opposed to being killed, showing that even the earliest humans may have had some sort of morality or ethics surrounding the cannibalizing of their kin, meaning they were aware of death in a social context as opposed to merely a physical one.<\/p>\n<p>While the original evidence in Krapina was uncovered in 1901, Croatian geologist and paleontologist Dragutin Gorjanovi\u0107-Kramberger\u2019s discovery of fragmented and burned human bones (Ullrich, 2005) was not yet confirmed to be linked to endocannibalism until much later. Whereas the discovery of burned bones does not mean they were being prepared for consummation, due to its context among other findings, this information supports the hypothesis that early hominids conducted post-mortem rituals and practices with their dead. Building on Gorjanovi\u0107-Kramberger\u2019s research, Herbert Ullrich wrote in <em>Anthropologie<\/em> (2005) that broken bones\u2014resulting from post-mortem bodily manipulations\u2014were \u201cdefleshed in preparation for secondary burial\u201d (2005, 251) and intentionally left outside rock shelters, while selectively chosen bones were seemingly brought inside for use in mortuary practices.<\/p>\n<p>For nearly 150 years, since the first Neanderthal skeletal remains were discovered, anthropologists and researchers have continued to debate the cognitive, social, and physical abilities of this species. In 2016, Rougier and colleagues wrote in <em>Scientific Reports<\/em>, furthering the research, presenting 99 new Neanderthal remains found in Goyet, Belgium. Among these remains, similar evidence of human-induced alterations was identified, including signs of butchering, consumption, and the use of bones to modify stone tools (Rougier Et al., 2016). This discovery provides significant support for the presence of cannibalistic behaviour among Northern European Neanderthals, contributing to the growing body of evidence that Neanderthals engaged with death in ways that reflect social awareness, ritual behaviour, and complex cultural practices.<\/p>\n<p><strong>Contemporary Cases of Prion Disease Related to Endocannibalism<\/strong><\/p>\n<p>The evidence of endocannibalism does not end with early hominids; with Australian medical anthropologists recording thousands of cannibalism-related prion disease occurrences present in populations up until 2009 (Radford &amp; Scragg, 2013). Following a mysterious epidemic of a new form of spongiform encephalopathy\u2013a \u201cprogressive degenerative disease of the central nervous system\u201d (2013, p.29)\u2013anthropological research regarding the the cultural mortuary rites within the Okapa region of Papua New Guinea have linked the newfound disease \u2018Kuru\u2019 to post-mortem consumption of human remains (Radford &amp; Scragg, 2013; Collinge Et al., 2006).<\/p>\n<p>Local oral histories collected during the first investigations by these researchers in the 1950s traced the earliest cases back to the 1920s, with detailed case histories. Epidemiological data revealed a strong correlation between the spread of Kuru and participation in mortuary feasts, in which the deceased were ritually consumed as part of funerary rites (2006, p. 2070). From 1957 to 2004, over 2,700 cases were reported, with mortality peaking at over 200 deaths annually in the late 1950s (2006, p.2070); however, following the cessation of cannibalism in the easly 1960s due to governmental efforts, natural transmission of the disease has stopped, dropping the death toll dramatically, with the \u201clast three single cases reported in 2005, 2007, and 2009\u201d (Radford &amp; Scragg, p.48).<\/p>\n<\/div>\n<h3 class=\"import-Normal\"><strong>The Lasting Gift of Neanderthals: Tantalizing New Directions for Resear<\/strong><strong>ch<\/strong><\/h3>\n<p class=\"import-Normal\">Examining the more recent time period in which Neanderthals lived and the extensive excavations completed across Europe allows for a much more complete archaeological record from this time period. Additionally, the increased cultural complexity such as complex tools and ritual behaviours expressed by Neanderthals left a more detailed record than previous hominins. Intentional burials enhanced preservation of the dead and potentially associated ritual behaviours. Such evidence allows for a more complete and nuanced picture of this species.<\/p>\n<figure style=\"width: 424px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image15-5.png\" alt=\"Museum exhibition of life-sized Neanderthal figure.\" width=\"424\" height=\"469\" \/><figcaption class=\"wp-caption-text\">Figure 12.12: Artistic reconstruction of Neanderthal at The Natural History Museum in Vienna, Austria. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Homo_neanderthalensis,_The_Natural_History_Museum_Vienna,_20210730_1223_1272.jpg\" target=\"_blank\">Homo neanderthalensis, The Natural History Museum Vienna, 20210730 1223 1272<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Jakubhal\" target=\"_blank\">Jakub Ha\u0142un<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/legalcode\" target=\"_blank\">CC BY 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Additional analyses are possible on many Neanderthal finds, due to increased preservation of bone, the amount of specimens that have been uncovered, and the recency in which Neanderthals lived. We should be cautious, however, to consider the potential bias of many Neanderthal sites. Overwhelmingly, Neanderthal skeletons are found complete, with injuries or evidence of disease in caves. Does this mean all Neanderthals lived a tough, disease-wrought life? Probably not. It does, however, indicate that the sick were cared for by others, and that they lived in environments that preserved their bodies incredibly well. These additional studies include the examination of dental calculus and even DNA analysis. While limited, samples of Neanderthal DNA have been successfully extracted and analysed. Research thus far has identified specific genetic markers that show some Neanderthals were light-skinned and probably red-haired with light eyes. Genetic analyses, different from the typical hominin reconstruction done with earlier species, allow scientists to further investigate soft tissue markers of Neanderthals and other more recent hominin species. These studies offer striking conclusions regarding Neanderthal traits, their physical appearance, and their culture, as reflected in these artists\u2019 reconstructions (Figure 12.12).<\/p>\n<figure style=\"width: 258px\" class=\"wp-caption alignright\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image17-4.png\" alt=\"Photograph of Dr. Svante P\u00e4\u00e4bo in a blue suit and red tie.\" width=\"258\" height=\"368\" \/><figcaption class=\"wp-caption-text\">Figure 12.13: Nobel Prize winner (2022) and pioneer in paleogenomic research, Dr. Svante P\u00e4\u00e4bo. Credit: <a href=\"https:\/\/upload.wikimedia.org\/wikipedia\/commons\/2\/26\/Professor_Svante_Paabo_ForMemRS_%28cropped%29.jpg\" target=\"_blank\">Professor Svante Paabo ForMemRS (cropped)<\/a> by Duncan.Hull is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Dr. Svante P\u00e4\u00e4bo (Figure 12.13), of the Max Planck Institute for Evolutionary Anthropology, has been at the forefront of much of this new research, largely in the form of genomic studies (The Nobel Prize 2022). Awarded the Nobel Prize for Physiology or Medicine in 2022, P\u00e4\u00e4bo is known primarily for his work with ancient DNA. He has successfully sequenced mitochondrial DNA (mtDNA) as well as the entire Neanderthal genome from nuclear DNA. His genomic work has led to the realization that Denisovans are genetically distinct from Neanderthals, as well as the recent identification of a Neanderthal father and teenage daughter, which he discovered by looking for unique DNA markers in the fossil record. Additionally, P\u00e4\u00e4bo\u2019s genomic work has provided researchers with additional lines of evidence regarding the connections between hominin fossils (such as Neanderthals) and modern people, their time of divergence, and current genetic overlap. The work of P\u00e4\u00e4bo has even formalized a new field of study within anthropology\u2014paleogenomics. To stay up to date with Dr. Svante P\u00e4\u00e4bo\u2019s work, be sure to follow his <a href=\"https:\/\/www.eva.mpg.de\/genetics\/neandertals-and-more\/overview\/\" target=\"_blank\">lab\u2019s website<\/a>.<\/p>\n<h3 class=\"import-Normal\"><strong>Neanderthal Culture: Communicating through Speech<\/strong><\/h3>\n<p class=\"import-Normal\">To successfully live in groups and to foster cultural innovations, Neanderthals would have required at least a basic form of communication in order to function, possibly using a speech-based communication system. The challenge with this line of research is that speech, of course, is not preserved, so indirect evidence must be used to support this conclusion. It is thought that Neanderthals would have possessed some basic speech, as evidenced from a variety of sources, including throat anatomy and genetic evidence (Lieberman 1971). There is only one bone in the human body that could demonstrate if a hominin was able to speak, or produce clear vocalizations like modern humans, and that is the hyoid, a U-shaped bone that is found in the throat and is associated with the ability to precisely control the vocal cords. Very few hyoid bones have been found in the archaeological record; however, a few have been uncovered in Neanderthal burials. The shape of the Neanderthal hyoid is nearly identical to that of modern humans, pointing to the likelihood that they had the same vocal capabilities as modern humans. In addition, geneticists have uncovered a mutation present in both modern humans and Neanderthals\u2014the FOXP2 gene\u2014that is possibly linked to the ability to speak. However, other scientists argue that we cannot make sweeping conclusions that the FOXP2 gene accounts for speech due to small sample size. Finally, scientists have also pointed to the increasingly complex cultural behaviour of Neanderthals as a sign that symbolic communication, likely through speech, would have been the only way to pass down the skills needed to make, for example, a Levallois blade or to position a body for intentional burial.<\/p>\n<h3 class=\"import-Normal\"><strong>Neanderthal Intelligence<\/strong><\/h3>\n<p class=\"import-Normal\">One of the enduring questions about Neanderthals centres on their intelligence, specifically in comparison to modern humans. Brain volume indicates that Neanderthals certainly had a large brain, but it continues to be debated if Neanderthals were of equal intelligence to modern humans. Remember, creatures with larger body sizes tend to have larger brains; however, scaling of the brain is not always associated with greater intelligence (Alex 2018). Brain volume (cranial capacity), cultural complexity, tool use, and compassion toward their kind all point to an increase in intellect among Neanderthals when compared to previous hominins.<\/p>\n<p class=\"import-Normal\">Yet, new research is suggesting additional differences between Neanderthal brains and our own. For example, Euluned Pearce and colleagues (2013), from the University of Oxford, noted the frontal lobes of Neanderthals and modern humans are almost identical. However, Neanderthals had a larger visual cortex\u2014the portion of the brain involved in processing visual information. This would have left Neanderthals with less brain tissue for other functions, including those that would have aided them in dealing with large social groupings, one of the differences that has been suggested to exist between Neanderthals and modern humans. Other differences were found when geneticist John Blangero, from the Texas Biomedical Research Institute, compared data from the Neanderthal genome against data from modern study participants. Blangero and his colleagues (Blangero Et al. 2014) discovered that some Neanderthal brain components were very different, and smaller, than those in the modern sample. Differences were found in areas associated with the processing of information and controlling emotion and motivation, as well as overall brain connectivity. In short, as Blangero stated, \u201cNeanderthals were certainly cognitively adept,\u201d although their specific abilities may have differed from modern humans\u2019 in key areas (qtd. in Wong 2015). This point has been echoed in other recent genetic studies comparing Neanderthal and anatomically modern human brains (el-Showk 2019).<\/p>\n<p class=\"import-Normal\">Finally, scientists are fairly certain that Neanderthal brain development after birth was not the same as that of modern humans. After birth, anatomically modern <em>Homo sapiens <\/em>babies go through a critical period of brain expansion and cognitive development. It appears that Neanderthal babies\u2019 brains and bodies did not follow the same developmental pattern (Smith Et al. 2010; Zollikofer and Ponce de Le\u00f3n 2013). Modern humans enjoy an extended period of childhood, which allows children to engage in imaginative play and develop creativity that fosters cognitive skills. Neanderthals had a more limited childhood, with less development of the creative mind that may have affected their species\u2019 success (Nowell 2016).<\/p>\n<p class=\"import-Normal\">The exact nature of Neanderthal intelligence remains under investigation, however. Some studies disagree with the idea that Neanderthal intelligence had limitations compared to our own, noting the extensive evidence of Neanderthals having limb asymmetry. Their tools also have wear marks indicating that they were hand-dominant. This is further supported by marks on Neanderthal teeth that demonstrate hand dominance. The Neanderthal \u201cstuff-and-cut method\u201d of eating, noted by David Frayer and colleagues (Frayer Et al. 2012), would have seen Neanderthals hold a piece of meat in their teeth, while pulling it taut with one hand, and then using the other hand, their dominant one, to cut the meat off of the larger slab being held in their teeth. When looking at 17 Neanderthals and their tooth wear, only two do not show markings associated with a right-hand dominant individual eating in this manner. Further, it has been established that favouring the right hand is a key marker between modern humans and chimpanzees, and that handedness also relates to language development, in the form of bilateral brain development. That Neanderthals likely were hand-dominant suggests they had an indicator of bilateral brain development and a precondition for human speech.<\/p>\n<h2 class=\"import-Normal\">The Middle Stone Age: Neanderthal Contemporaries in Africa<\/h2>\n<p class=\"import-Normal\">While Neanderthals made their home on and adapted to the European and Asian continents, evidence of fossil humans in Africa show they were also adapting to their local environments. These populations in Africa exhibit many more similarities to modern humans than Neanderthals, as well as overall evolutionary success. While the African fossil sample size is smaller and more fragmentary than the number of Neanderthal specimens across Europe and Asia, the African sample is interesting in that it represents a longer time period and larger geographical area. This group of fossils\u2014often represented by the name \u201cMiddle Stone Age,\u201d or MSA\u2014dates to between 300,000 and 30,000 years ago across the entire continent of Africa. As with Archaic <em>Homo sapiens<\/em>, there is much variability seen in this African set of fossils. There are also a few key consistent elements: none of them exhibit Neanderthal skeletal features; instead, they demonstrate features that are increasingly consistent with anatomically modern <em>Homo sapiens<\/em>.<\/p>\n<p class=\"import-Normal\">Similarities to Neanderthals and MSA contemporaries in Africa are seen, however, in their behavioural adaptations, including stone tools and other cultural elements. The tools associated with the specimens living in Africa during this time period are, like their physical features, varied. In some parts of Africa, namely Northern Africa, stone tools from this time so closely resemble Neanderthal tools that they are classified as Mousterian. In sub-Saharan Africa, the stone tools associated with these specimens are labeled as MSA. Some scholars argue that these could also be a type of Mousterian tools, but they are still typically subdivided based on geographical location.<\/p>\n<p class=\"import-Normal\">Recall that Mousterian tools were much more advanced than their Acheulean predecessors in terms of how the stone tools were manufactured, the quality of the stones used, and the ultimate use of the tools that were made. In addition, recent evidence suggests that MSA tools may also have been heat treated\u2014to improve the quality of the stone tool produced (Stolarczyk and Schmidt 2018). Evidence for heat treating is seen not only through advanced analysis of the tool itself but also through the residue of fires from this time period. Fire residues show a shift over time from small, short fires fuelled by grasses (probably intended for cooking) to larger, more intensive fires that required the exploitation of dry wood, exactly the type of fire that would have been needed for heat treating stone tools (Esteban Et al. 2018).<\/p>\n<p class=\"import-Normal\">Other cultural elements seen with MSA specimens include the use of marine (sea-based) resources for their diet (Parkington 2003), manufacture of bone tools, use of adhesive and compound tools (e.g., hafted tools), shell bead production, engraving, use of pigments (such as ochre), and other more advanced tool-making technology (e.g., microlithics). While many of these cultural elements are also seen to a limited extent among Neanderthals, developments at MSA sites appear more complex. This MSA cultural expansion may have been a response to climate change or an increased use of language, complex communication, and\/or symbolic thought. Others have suggested that the MSA cultural expansion was due to the increase of marine resources in their diet, which included more fatty acids that may have aided their cognitive development. Still others have suggested that the increased cultural complexity was due to increased interaction among groups, which spurred competition to innovate. Recent studies suggest that perhaps the best explanation for the marked cultural complexity of MSA cultural artifacts is best explained by the simple fact that they lived in diverse habitats (Kandel Et al. 2015). This would have necessitated a unique set of cultural adaptations for each habitat type (for example, specialized marine tools would have been needed along coastal sites but not at inland locations). Simply put, the most useful adaptation of MSA was their flexibility of behaviour and adaptability to their local environment. As noted previously in this chapter, flexibility of behaviour and physical traits, rather than specialization, seems to be a feature that was favoured in hominin evolution at this time.<\/p>\n<h2 class=\"import-Normal\">Where Did They Go? The End of Neanderthals<\/h2>\n<p class=\"import-Normal\">While MSA specimens were increasingly successful and ultimately transitioned into modern <em>Homo sapiens<\/em>, Neanderthals disappeared from the fossil record by around 40,000 years ago. What happened to them? We know, based on genetics, that modern humans come largely from the modern people who occupied Africa around 300,000 to 100,000 years ago, at the same time that Neanderthals were living in northern Europe and Asia. As you will learn in Chapter 13, modern humans expanded out of Africa around 150,000 years ago, rapidly entering areas of Europe and Asia inhabited by Neanderthals and other Archaic hominins. Despite intense interest and speculation in fictional works about possible interactions between these two groups, there is very little direct evidence of either peaceful coexistence or aggressive encounters. It is clear, though, that these two closely related hominins shared Europe for thousands of years, and recent DNA evidence suggests that they occasionally interbred (Fu Et al. 2015). Geneticists have found traces of Neanderthal DNA (as much as 1% to 4%) in modern humans of European and Asian descent not present in modern humans from sub-Saharan Africa. This is indicative of limited regional interbreeding with Neanderthals.<\/p>\n<p class=\"import-Normal\">While some interbreeding likely occurred, as a whole, Neanderthals did not survive. What is the cause for their extinction? This question has fascinated many researchers and several theories\u00a0have been suggested, including:<\/p>\n<ul>\n<li class=\"import-Normal\">At the time that Neanderthals were disappearing from the fossil record, the climate went through both cooling and warming periods\u2014each of which posed challenges for Neanderthal survival (Defleur and Desclaux 2019; Staubwasser Et al. 2018). It has been argued that as temperatures warmed, large-bodied animals, well adapted to cold weather, moved farther north to find colder environments or faced extinction. A shifting resource base could have been problematic for continued Neanderthal existence, especially as additional humans, in the form of modern <em>Homo sapiens<\/em>, began to appear in Europe and compete for a smaller pool of available resources.<\/li>\n<li class=\"import-Normal\">It has been suggested that the eruption of a European volcano 40,000 years ago could have put a strain on available plant resources (Golovanova Et al. 2010). The eruption would have greatly affected local microclimates, reducing the overall temperature enough to alter the growing season.<\/li>\n<li class=\"import-Normal\">Possible differences in cognitive development may have limited Neanderthals in terms of their creative problem solving. As much as they were biologically specialized for their environment, the nature of their intelligence might not have offered them the creative problem-solving skills to innovate ways to adapt their culture when faced with a changing environment (Pearce Et al. 2013).<\/li>\n<li class=\"import-Normal\">CRISPR gene-editing technology has been used in studies to evaluate potential differences between human and Neanderthal brains, based on differences in the genetic code. Potential differences include a Neanderthal propensity for mutations related to brain development that could account for more rapid brain development, maturation, synapse misfires, and less-orderly neural processes (Mora-Berm\u00fadez Et al. 2022; Trujillo Et al. 2021). Fundamental differences in brain function at the cellular level may account for the differential survival rates of Neanderthal and modern human populations.<\/li>\n<li class=\"import-Normal\">There is evidence that suggests reproduction may have posed challenges for Neanderthals. Childbirth was thought to have been at least as difficult for female Neanderthals as anatomically modern <em>Homo sapiens<\/em> (Weaver and Hublin 2009). Female Neanderthals may have become sexually mature at an older age, even older than modern humans. This delayed maturation could have kept the Neanderthal population size small. A recent study has further suggested that male Neanderthals might have had a genetic marker on the Y chromosome that could have caused incompatibility between the fetus and mother during gestation; this would have had severe consequences for birth rate and survival (Mendez Et al. 2016). Even a small but continuous decrease in fertility would have been enough to result in the extinction of Neanderthals (Degioanni Et al. 2019).<\/li>\n<li class=\"import-Normal\">As mentioned above, the end of Neanderthal existence overlaps with modern human expansion into northern Europe and Asia. There is no conclusive direct evidence to indicate that Neanderthals and modern humans lived peacefully side by side, nor that they engaged in warfare, but by studying modern societies and the tendencies of modern humans, it has been suggested that modern humans may not have warmly embraced their close but slightly odd-looking cousins when they first encountered them (Churchill Et al. 2009). Nevertheless, direct competition with modern humans for the same resources may have contributed to the Neanderthals\u2019 decline (Gilpin Et al. 2016); it may also have exposed them to new diseases, brought by modern humans (Houldcroft and Underdown 2016), which further decimated their population. Estimates of energy expenditures suggest Neanderthals had slightly higher caloric needs than modern humans (Venner 2018). When competing for similar resources, the slightly greater efficiency of modern humans might have helped them experience greater success in the face of competition\u2014at a cost to Neanderthals.<\/li>\n<\/ul>\n<p class=\"import-Normal\">It has been suggested that the Neanderthal populations were fairly small to begin with (estimated between 5,000 and 70,000 individuals; Bocquet-Appel and Degioanni 2013), one or a combination of these factors could have easily led to their demise. As more research is conducted, we will likely get a better picture of exactly what led to Neanderthal extinction.<\/p>\n<h2 class=\"import-Normal\">Denisovans<\/h2>\n<figure style=\"width: 353px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image16-4.png\" alt=\"Small fossilized finger bone sitting atop a chalk outline of hand bones.\" width=\"353\" height=\"235\" \/><figcaption class=\"wp-caption-text\">Figure 12.14: Reproduction of Denisovan finger bone. Credit: <a href=\"https:\/\/upload.wikimedia.org\/wikipedia\/commons\/6\/6f\/Denisova_Phalanx_distalis.jpg\" target=\"_blank\">Denisova Phalanx distalis<\/a> (image from Museum of Natural Sciences, Brussels, Belgium) by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Thilo_Parg\" target=\"_blank\">Thilo Parg<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">While Neanderthals represent one regionally adapted branch of the Archaic <em>Homo sapiens <\/em>family tree, recent discoveries in Siberia and the Tibetan Plateau surprised paleoanthropologists by revealing yet another population that was contemporary with Archaic <em>Homo sapiens<\/em>, Neanderthals, and modern <em>Homo sapiens<\/em>. The genetic analysis of a child\u2019s finger bone (Figure 12.14) and an adult upper third molar (Figure 12.15) from Denisova Cave in the Altai Mountains in Siberia by a team including Svante P\u00e4\u00e4bo discovered that the mitochondrial and nuclear DNA sequences reflected distinct genetic differences from all known Archaic populations. Dubbed \u201cDenisovans\u201d after the cave in which the bones were found, this population is more closely related to Neanderthals than modern humans, suggesting the two groups shared an ancestor who split from modern humans first, then the Neanderthal-Denisovan line diverged more recently (Reich Et al. 2010).<\/p>\n<figure style=\"width: 227px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image6-4-1.png\" alt=\"Molar tooth with wear, large surface area, and large roots.\" width=\"227\" height=\"341\" \/><figcaption class=\"wp-caption-text\">Figure 12.15: Reproduction of Denisovan molar. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Denisova_Molar.jpg\" target=\"_blank\">Denisova Molar<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Thilo_Parg\" target=\"_blank\">Thilo Parg<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Denisovans share up to 5% of their DNA with modern Melanesians, aboriginal Australians, and Polynesians, and 0.2% of their DNA with other modern Asian populations and Native Americans. Additional studies have suggested one (Vernot Et al. 2018) or two (Browning Et al. 2018) separate points of time when interbreeding occurred between modern humans and Denisovans.<\/p>\n<p class=\"import-Normal\">Genetic analysis reveals that Denisovans (potentially three distinct populations) had adaptations for life at high altitudes that prevented them from developing altitude sickness and hypoxia in extreme environments such as Tibet, where the average annual temperature is close to 0\u2103 and the altitude is more than a kilometre (about 4,000 feet) above sea level. Through protein analysis of a jawbone, one study (Chen Et al. 2019) has placed Denisovans in Tibet as early as 160,000 years ago. Genetic evidence of interbreeding has linked modern Tibetan populations with Denisovans 30,000 to 40,000 years ago, which implies that the unique high-altitude adaptations seen in modern Tibetans may have originated with Denisovans (Huerta-Sanchez Et al. 2014).<\/p>\n<p class=\"import-Normal\">Other research suggests tantalizing new directions regarding Denisovans. Stone tools similar to those found in Siberia have been uncovered in the Tibetan plateau suggesting a connection between the Denisovan populations in those two areas (Zhang Et al. 2018). The molar of a young girl, possibly Denisovan, has been found in Laos and shows strong similarities to specimens from China (Demeter Et al. 2022). And DNA sequencing from discoveries in the Denisova Cave have yielded a genome that has been interpreted as the first-generation offspring of a Denisovan father and Neanderthal mother (Slon Et al. 2018). While this research is not yet conclusive and is still being interpreted, exciting new possibilities are being revealed. To stay up-to-date with new discoveries, consider following organizations such as the <a href=\"https:\/\/www.facebook.com\/smithsonian.humanorigins\/\" target=\"_blank\">Smithsonian\u2019s Human Origins Program<\/a> on social media.<\/p>\n<div class=\"textbox\" style=\"background: var(--lightblue)\">\n<h2>Pleistocene Hominins in East Asia: Homo longi and Yunxian<\/h2>\n<p>New fossil discoveries, along with advanced molecular analysis, are prompting re-evaluations of the complex evolutionary dynamics of non-sapiens Homo in the middle-late Pleistocene.<\/p>\n<h3>Homo longi<\/h3>\n<p>The Harbin cranium, often referred to as Homo longi, represents one of the most remarkable Middle Pleistocene human fossils discovered in East Asia. It is currently carbon-dated at 146 ka, allowing recent scholarship to use the Harbin cranium to argue for a distinct clade of hominins that evolved independently in Eastern Asia, separate from Neanderthals and modern humans (Ni et al., 2021). This clade is argued to include Dali, Jinniushan, Hualongdong, Xiahe, and Harbin, based on phylogenetic analyses using parsimony criteria and Bayesian tip-dating, forming a third East Asian lineage and a sister group to the Homo sapiens lineage.<\/p>\n<p>The Harbin cranium exhibits a unique combination of traits, likely representing a species of Homo distinct from other Middle-to-Late Pleistocene taxa, including H. sapiens, H. Neanderthalensis, and H. Heidelbergensis\/H. Rhodesiensis. Its overall size is exceptional, setting it apart from nearly all other known fossils; however, the proportions of the cranial vault align closely with those of other large late archaic Homo species, with an estimated brain volume of approximately 1,420 mL. Despite its considerable breadth, the face is relatively low in height and exhibits a zygomaxillary shape similar to that seen in H. sapiens and H. antecessor, a feature also observed in other Middle Pleistocene Chinese fossils from Dali and Jinniushan. Additionally, the face is attached to the braincase with reduced prognathism, forming a more perpendicular angle as in modern humans, in contrast to the pronounced midfacial prognathism of Neanderthals.<\/p>\n<h3>Yunxian, China: Possible cladistic origins<\/h3>\n<p>In 2025, researchers released findings that expanded the diversity and relationships of Homo lineages in the Pleistocene, based on an analysis of fossils found in 1989\/90. Two skull fossils were found near the Hanjiang River in Hubei province, China, and were named the Yunxian 1 and Yunxian 2 crania\u2014A third cranium has recently been discovered in the same sediment layer as the two previous finds (Tu et al., 2026). The first 2 specimens were in poor condition, fragmented and distorted; however, using recently developed techniques such as high-resolution computed tomography (CT) scans, image segmentation, and digital repositioning of fragments, the researchers incorporated elements from the Yunxian 1 crania with the less damaged Yunxian 2 cranium. The Yunxian 2 cranium is a mosaic of primitive and derived traits. It retains ancient characteristics seen in earlier hominins, a thick supraorbital torus, a broad palate, a long and low vault in lateral view, and a receding frontal contour; its frontal lobe remains low and narrow, similar to H. erectus fossils. Conversely, it lacks the strongly angulated occipital bone found in H. erectus as well as the protruding occipital region or central suprainiac fossa typical of Neanderthals. The big surprise is that the zygomaxillary region is transversely flat and faces anteriorly, a feature comparable to the Hualongdong and Harbin fossils and even H. sapiens. This intermediate morphology places Yunxian 2 in a distinct position, linking archaics like H. erectus with later Asian hominins such as Harbin, Dali, and Jinniushan. Phylogenetic and morphometric analyses confirm that Yunxian 2 represents an early member of the Asian H.longi Clade. The reconstructed Yunxian 2 cranium represents a major achievement in paleoanthropology, digitally restoring a badly damaged fossil from beyond the Middle Pleistocene. In fact, recent discussion suggests an even earlier date for the Yunxian fossils at approximately 1.77 Ma (Tu et al., 2026). In their analysis, they identify the Yunxian fossils as H.erectus, and the site as Early Pleistocene. Over 500 artifacts have been recovered from the site (cores, choppers, and flakes) typical of the Early Paleolithic. Nevertheless, the mosaic morphology of the Yunxian skulls reveals characteristics within the range of both H. erectus and the Harbin skull (among others), which may position these finds as being very close to the origins and diversification of the longi clade, as well as preserving transitional features close to the sapiens clade\u00a0 (Feng et al., 2025, p.1323).<\/p>\n<p>The expanding fossil and genomic record of Archaic Homo has profoundly reshaped our understanding of Pleistocene human evolution. Discoveries, from an increasing variety of fossils found in eastern Asia, to advances in genomic research, demonstrate that multiple contemporaneous lineages once coexisted, interacted, diverged and, at times, interbred. These findings challenge earlier linear models of human ancestry and instead point to a dynamic evolutionary landscape marked by regional diversification, intermittent contact, and complex patterns of gene flow.<\/p>\n<\/div>\n<p>&nbsp;<\/p>\n<h2 class=\"import-Normal\">How Do These Fit In? <em>Homo naledi<\/em> and <em>Homo floresiensis<br \/>\n<\/em><\/h2>\n<p class=\"import-Normal\">Recently, some fossils have been unearthed that have challenged our understanding of the hominin lineage. The fossils of <em>Homo <\/em><em>naledi<\/em> and <em>Homo <\/em><em>floresiensis<\/em> are significant for several reasons but are mostly known for how they don\u2019t fit the previously held patterns of hominin evolution. While we examine information about these species, we ask you to consider the evidence presented in this chapter and others to draw your own conclusions regarding the significance and placement of these two unusual fossil species in the hominin lineage.<\/p>\n<h3 class=\"import-Normal\"><strong>Homo <\/strong><strong>naledi<\/strong><\/h3>\n<figure style=\"width: 347px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image12-5.png\" alt=\"A nearly complete skeleton surrounded by off-white bone fragments on a black table.\" width=\"347\" height=\"390\" \/><figcaption class=\"wp-caption-text\">Figure 12.16: A sample of some of the 1,550 bones found representing Homo naledi. Credit: <a href=\"https:\/\/elifesciences.org\/articles\/09560#fig1\" target=\"_blank\">Dinaledi skeletal specimens (Figure 1)<\/a> by <a href=\"https:\/\/elifesciences.org\/articles\/09560\" target=\"_blank\">Berger et al. 2015<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/legalcode\" target=\"_blank\">CC BY 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">In 2013 recreational spelunkers uncovered a collection of bones deep in a cave network in Johannesburg, South Africa. The cave system, known as Rising Star, had been well documented by other cavers; however, it appears few people had ever gone as far into the cave as these spelunkers did. Lee Berger, paleoanthropologist at University of Witwatersrand, in Johannesburg, immediately put out a call for what he termed \u201cunderground astronauts\u201d to begin recovery and excavation of the fossil materials. Unlike other excavations, Berger and most other paleoanthropologists would not be able to access the elusive site, as it was incredibly difficult to reach, and at some points there was only eight inches of space through which to navigate. The underground astronauts, all petite women anthropologists, were the only ones who were able to access this remarkable site. Armed with small excavation tools and a video camera, which streamed the footage up to the rest of the team at the surface, the team worked together and uncovered a total of 1,550 bones, representing at least 15 individuals, as seen in Figure 12.16. Later, an additional 131 bones, including an almost-complete cranium, were found in a nearby chamber of the cave, representing three more individuals (Figure 12.17). Berger called in a team of specialists to participate in what was dubbed \u201cPaleoanthropology Summer Camp.\u201d Each researcher specialized in a different portion of the hominin skeleton. With various specialists working simultaneously, more rapid analysis was possible of <em>Homo <\/em><em>naledi<\/em> than most fossil discoveries.<\/p>\n<p>&nbsp;<\/p>\n<figure style=\"width: 534px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image2-4.png\" alt=\"Photograph of four different views of the LES1 Homo naledi skull set against a black background.\" width=\"534\" height=\"599\" \/><figcaption class=\"wp-caption-text\">Figure 12.17: Several angles of the nearly complete LES1 Homo naledi skull. Credit: <a href=\"https:\/\/elifesciences.org\/articles\/24232#fig5\" target=\"_blank\">LES1 Cranium (Figure 5)<\/a> by <a href=\"https:\/\/elifesciences.org\/articles\/24232\" target=\"_blank\">Hawks et al. 2017<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/legalcode\" target=\"_blank\">CC BY 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">While access to the site, approximately 80 m from any known cave entrance or opening, was treacherous for researchers, it must have been difficult for <em>Homo <\/em><em>naledi<\/em> as well. The route included moving through a portion that is just 25 cm wide at some points, known as \u201cSuperman\u2019s Crawl.\u201d The only way to get through this section is by crawling on your stomach with one arm by your side and the other raised above your head. Past Superman\u2019s Crawl, a jagged wall known as the Dragon\u2019s Back would have been very difficult to traverse. Below that, a narrow vertical chute would have eventually led down to the area where the fossils were discovered. While geology changes over time and the cave system likely has undergone its fair share, it is not likely that these features arose after <em>Homo <\/em><em>naledi<\/em> lived (Dirks Et al. 2017). This has made scientists curious as to how the bones ended up in the bottom of the cave system in the first place. It has been suggested that <em>Homo <\/em><em>naledi<\/em> deposited the bones there, one way or another. If <em>Homo <\/em><em>naledi<\/em> did deposit the bones, either through random disposal or intentional burial, this raises questions regarding their symbolic behaviour and other cultural traits, including the use of fire, to access a very dark cave system. Another competing idea is that a few individuals may have entered the cave system to escape a predator and then got stuck. To account for the sheer number of fossils, this would have had to happen multiple times.<\/p>\n<p class=\"import-Normal\">The features of <em>Homo <\/em><em>naledi<\/em> are well-documented due to the fairly large sample, which represents individuals of all sexes and a wide range of ages. The skull shape and features are very much like other members of the genus <em>Homo<\/em>\u2014including a sagittal keel and large brow, like <em>Homo <\/em><em>erectus<\/em>, and a well-developed frontal lobe, similar to modern humans\u2014yet the brain size is significantly smaller than its counterparts, at approximately 500 cc (560 cc for males and 465 cc for females). The teeth also exhibit features of later members of the genus <em>Homo<\/em>, such as Neanderthals, including a reduction in overall tooth size. <em>Homo <\/em><em>naledi<\/em> also had unique shoulder anatomy and curved fingers, indicating similarities to tree-dwelling primates, which is very different from any other hominin yet found. Perhaps the greatest shock of all is that <em>Homo <\/em><em>naledi<\/em> has been dated to 335,000 to 236,000 years ago, placing it as a contemporary to modern <em>Homo sapiens,<\/em> despite its very primitive features. An additional specimen of a child, found in 2021, not only shares many of the unique features found in the adult specimen but will also add insight into the growth and development of individuals of this species (Brophy Et al. 2021).<\/p>\n<h3 class=\"import-Normal\"><strong>Homo <\/strong><strong>floresiensis<\/strong><\/h3>\n<p class=\"import-Normal\">In a small cave called Liang Bua, on the island of Flores, in Indonesia, a small collection of fossils were discovered beginning in 2003 (Figure 12.18). The fossil fragments represent as many as nine individuals, including a nearly complete female skeleton. The features of the skull are very similar to that of <em>Homo <\/em><em>erectus<\/em>, including the presence of a sagittal keel, an arching brow ridges and nuchal torus, and the lack of a chin (Figure 12.19). <em>Homo <\/em><em>floresiensis<\/em>, as the new species is called, had a brain size that was remarkably small at 400 cc, and recent genetic studies suggest a common ancestor with modern humans that predates <em>Homo <\/em><em>erectus<\/em>.<\/p>\n<figure style=\"width: 606px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image8-3.png\" alt=\"View from inside a large cave with people standing near a dug-out square of dirt.\" width=\"606\" height=\"403\" \/><figcaption class=\"wp-caption-text\">Figure 12.18: Liang Bua Cave on the island of Flores, in Indonesia, where a collection of Homo floresiensis specimens were discovered. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Homo_floresiensis_cave.jpg\" target=\"_blank\">Homo floresiensis cave<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/84301190@N00\" target=\"_blank\">Rosino<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\" target=\"_blank\">CC BY-SA 2.0 License<\/a>.<\/figcaption><\/figure>\n<figure style=\"width: 584px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image9-5.png\" alt=\"Photograph of a gray and off-white cast Homo floresiensis skull.\" width=\"584\" height=\"584\" \/><figcaption class=\"wp-caption-text\">Figure 12.19: Homo floresiensis had a brain that was remarkably small at 400 cc. Recent genetic studies suggest a common ancestor with modern humans that predates Homo erectus. Credit: <a href=\"https:\/\/boneclones.com\/product\/homo-floresiensis-skull-BH-033-2\" target=\"_blank\">Homo floresiensis Skull (Flores Skull LB1)<\/a> by <a href=\"https:\/\/boneclones.com\/\" target=\"_blank\">\u00a9BoneClones<\/a> is used by permission and available here under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">The complete female skeleton, who was an adult, was approximately a metre tall and would have weighed just under 30 kg, which is significantly shorter and just a few kilograms more than the average, modern, young elementary-aged child. A reconstructed comparison between an anatomically modern human and <em>Homo <\/em><em>floresiensis<\/em> can be seen in Figure 12.20. The small size of the fossil has earned the species the nickname \u201cthe Hobbit.\u201d Many questions have been asked about the stature of this species, as all of the specimens found also show evidence of diminutive stature and small brain size. Some explanations include pathology; however, this seems unlikely as all fossils found thus far demonstrate the same pattern. Another possible explanation lies in a biological phenomena seen in other animal species also found on the island, which date to a similar time period. This phenomenon, called <strong>insular dwarfing<\/strong>, is due to limited food resources on an island, which can create a selective pressure for large-bodied species to be selected for smaller size, as an island would not have been able to support their larger-bodied cousins for a long period of time. This phenomenon is the cause of other unique species known to have lived on the island at the same time, including the miniature stegodon, a dwarf elephant species.<\/p>\n<figure style=\"width: 448px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image18-4.png\" alt=\"Black-and-white drawing of a large nude woman and a much smaller man.\" width=\"448\" height=\"611\" \/><figcaption class=\"wp-caption-text\">Figure 12.20: A reconstructed comparison between an anatomically modern human and Homo floresiensis. As an adult, Homo floresiensis was approximately 1 metre tall and would have weighed under 30 kg. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-16\/\" target=\"_blank\">Anatomically modern human and Homo floresiensis (Figure 11.19)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">There is ongoing research and debate regarding <em>Homo floresiensis<\/em>\u2019 dates of existence, with some researchers concluding that they lived on Flores until perhaps as recently as 17,000 years ago, although they are more often dated to 100,000 to 60,000 years ago. Stone tools from that time period uncovered at the site are similar to other hominin stone tools found on the island of Flores. <em>Homo <\/em><em>floresiensis<\/em> would have hunted a wide range of animals, including the miniature stegodon, giant rats, and other large rodents. Other animals on the island that could have threatened them include the giant komodo dragon. An interesting note about this island chain is that ancestors of <em>Homo <\/em><em>floresiensis<\/em> would have had to traverse the open ocean in order to get there, as the nearest island is almost 10 km away, and there is little evidence to support that a land bridge connecting mainland Asia or Australia to the island would have been present. This separation from the mainland would also have limited the number of other animals, including predators and human species, that would have had access to the island. Anatomically modern <em>Homo sapiens<\/em> arrived on the island around 30,000 years ago and, if some researchers\u2019 later dates for <em>Homo <\/em><em>floresiensis<\/em> are correct, both species may have lived on Flores at the same time. The modern population living on the island of Flores today believes that their ancestors came from the Liang Bua cave; however, recent genetic studies have determined they are not related to <em>Homo <\/em><em>floresiensis<\/em> (Tucci Et al. 2018).<\/p>\n<h2 class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">Hominin Species Summaries<\/span><\/h2>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<tbody>\n<tr class=\"Table3-R\" style=\"height: 0\">\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Hominin<\/strong><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Archaic <em>Homo sapiens<\/em><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 0\">\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dates<\/strong><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">600,000\u2013200,000 years ago (although some regional variation)<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 0\">\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Region(s)<\/strong><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Africa, Europe, and Asia<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 0\">\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Famous discoveries<\/strong><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Broken Hill (Zambia), Atapuerca (Spain)<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 0\">\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Brain size<\/strong><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1,200 cc average<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 0\">\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dentition<\/strong><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Slightly smaller teeth in back of mouth, larger front teeth<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 0\">\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Cranial features<\/strong><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Emerging forehead, no chin, projecting occipital region<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 0\">\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Postcranial features<\/strong><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Robust skeleton<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 0\">\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Culture<\/strong><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Varied regionally, but some continue to use Acheulean handaxe, others adopt Mousterian tool culture<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 0\">\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Other <\/strong><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Lots of regional variation in this species<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<tbody>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Species<\/strong><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><em>Homo <\/em><em>naledi<\/em><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dates<\/strong><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">335,000\u2013236,000 years ago<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Region(s)<\/strong><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">South Africa<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Famous discoveries<\/strong><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Rising Star Cave<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Brain size<\/strong><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">500 cc average<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dentition<\/strong><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Reduced tooth size<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Cranial features<\/strong><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Sagittal keel, large brow, well-developed frontal region<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Postcranial features<\/strong><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Suspensory shoulder<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Culture<\/strong><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">unknown<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Other<\/strong><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">N\/A<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<tbody>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Hominin<\/strong><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Neanderthals<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dates<\/strong><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">150,000\u201340,000 years ago<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Region(s)<\/strong><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Western Europe, Middle East, and Western Asia only<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Famous discoveries<\/strong><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Shanidar (Iraq), La Chapelle-aux-Saints (France)<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Brain size<\/strong><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1500 cc average<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dentition<\/strong><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Retromolar gap<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Cranial features<\/strong><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Large brow ridge, midfacial prognathism, large infraorbital foramina, occipital bun<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Postcranial features<\/strong><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Robust skeleton with short and stocky body, increased musculature, barrel chest<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Culture<\/strong><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Mousterian tools often constructed using the Levallois technique<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Other<\/strong><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">N\/A<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<tbody>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Species<\/strong><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><em>Homo <\/em><em>floresiensis<\/em><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dates<\/strong><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">100,000\u201360,000 years ago, perhaps as recently as 17,000 years ago<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Region(s)<\/strong><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Liang Bua, island of Flores, Indonesia<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Famous discoveries<\/strong><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">\u201cThe Hobbit\u201d<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Brain size<\/strong><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">400 cc average<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dentition<\/strong><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">unknown<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Cranial features<\/strong><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Sagittal keel, arching brow ridges, nuchal torus, no chin<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Postcranial features<\/strong><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Very short stature (approximately 3.5 ft.)<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Culture<\/strong><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Tools similar to other tools found on the island of Flores<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Other<\/strong><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">N\/A<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<tbody>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Hominin<\/strong><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Denisovans<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dates<\/strong><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">100,000\u201330,000 years ago<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Region(s)<\/strong><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Siberia<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Famous discoveries<\/strong><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Child\u2019s finger bone and adult molar<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Brain size<\/strong><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">unknown<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dentition<\/strong><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Large molars (from limited evidence)<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Cranial features<\/strong><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">unknown<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Postcranial features<\/strong><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">unknown<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Culture<\/strong><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">unknown<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Other <\/strong><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Closely related to Neanderthals (genetically)<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div class=\"textbox shaded\">\n<h2 class=\"import-Normal\">Summary<\/h2>\n<p class=\"import-Normal\">Research presented in the chapter contributes to why scientists have taken to nicknaming this time period \u201cthe muddle in the middle.\u201d We know that the Middle Pleistocene picks up from <em>Homo erectus <\/em>and ends with the appearance of anatomically modern <em>Homo sapiens<\/em>. While the start and the end are clear, it\u2019s the middle that is messy. As more research is conducted and more data is collected, rather than clarifying our understanding of the hominin lineage during this time period, it only inspires more questions, particularly about the relationships between hominins during this time period, including the oft-misunderstood Neanderthal. Research is painting a more detailed picture of Neanderthal intelligence and both biological and behavioural adaptations. At the same time, their relationship to other Middle Pleistocene hominins, including Denisovans, as well as modern humans, remains unclear.<\/p>\n<p class=\"import-Normal\"><em>Homo<\/em> <em>naledi<\/em> and <em>Homo <\/em><em>floresiensis<\/em> are clear outliers when compared to their contemporary hominin species. Each has surprised paleoanthropologists for both their archaic traits in relatively modern times and their unique combination of traits seen in archaic species and modern humans. While these finds have been exciting, they have also completely upended the assumed trajectory of the human lineage, causing scientists to re-examine assumptions about hominin evolution and what it means to be modern. Add this to the developments being made using ancient DNA, other new fossil discoveries, and other innovations in paleoanthropology, and you see that our understanding of Archaic <em>Homo sapiens<\/em> and others living during this time period is rapidly developing and changing. This is a true testament to the nature of science and the scientific method.<\/p>\n<p class=\"import-Normal\">Clearly, hominins of the Middle Pleistocene are distinct from our species today. Yet, understanding the hominins that directly preceded our species and clarifying the evolutionary relationships between us is important to better understanding our own place in nature.<\/p>\n<h2 class=\"import-Normal\">Review Questions<\/h2>\n<ul>\n<li>What physical and cultural features are unique to Archaic<em> Homo sapiens<\/em>? How are Archaic<em> Homo sapiens<\/em> different in both physical and cultural characteristics from <em>Homo <\/em><em>erectus<\/em>?<\/li>\n<li>Describe the specific changes to the brain and skull first seen in Archaic<em> Homo sapiens<\/em>. Why does the shape of the skull change so dramatically from <em>Homo <\/em><em>erectus<\/em>?<\/li>\n<li>What role did the shifting environment play in the adaptation of Archaic <em>Homo sapiens<\/em>, including Neanderthals? Discuss at least one physical feature and one cultural feature that would have assisted these groups in surviving the changing environment.<\/li>\n<li>What does the regional variation in Archaic <em>Homo sapiens<\/em> represent in terms of the broader story of our species\u2019 evolution?<\/li>\n<li>Describe the issues raised by the discoveries of <em>Homo <\/em><em>naledi<\/em> and <em>Homo <\/em><em>floresiensis<\/em> in the understanding of the story of the evolution of <em>Homo sapiens<\/em>.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<h2 class=\"__UNKNOWN__\">Key Terms<\/h2>\n<div class=\"__UNKNOWN__\">\n<p><strong>Allele<\/strong>: Each of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome.<\/p>\n<p class=\"import-Normal\"><strong>Anthropocentrism<\/strong>: A way of thinking that assumes humans are the most important species and leads to interpreting the world always through a human lens. Species-centric science and thought.<\/p>\n<p class=\"import-Normal\"><strong>Cortex<\/strong>: The outside, or rough outer covering, of a rock. Usually the cortex is removed during the process of stone tool creation.<\/p>\n<p class=\"import-Normal\"><strong>Ethnocentric<\/strong>: Applying negative judgments to other cultures based on comparison to one\u2019s own.<\/p>\n<p class=\"import-Normal\"><strong>Exogenous DNA<\/strong>: DNA that originates from sources outside of the specimen you are trying to sequence.<\/p>\n<p class=\"import-Normal\"><strong>Flexed position<\/strong>: Fetal position, in which the legs are drawn up to the middle of the body and the arms are drawn toward the body centre. Intentional burials are often found in the flexed body position.<\/p>\n<p class=\"import-Normal\"><strong>Foraminifera<\/strong>: Microscopic single-celled organisms with a shell that are common in all marine environments. The fossil record of foraminifera extends back well over 500 million years.<\/p>\n<p class=\"import-Normal\"><strong>Glaciation<\/strong>: A glacial period, or time when a large portion of the world is covered by glaciers and ice sheets.<\/p>\n<p class=\"import-Normal\"><strong>Globular<\/strong>: Round-shaped, like a globe.<\/p>\n<p class=\"import-Normal\"><strong>Grave goods<\/strong>: Items included with a body at burial. Items may signify occupation or hobbies, social status, or level of importance in the community, or they may be items believed necessary for the afterlife.<\/p>\n<p class=\"import-Normal\"><strong>Haft<\/strong>: A handle. Also used as a verb\u2014to attach a handle to an item, such as a stone tool.<\/p>\n<p class=\"import-Normal\"><strong>Infraorbital foramina<\/strong>: Small holes on the maxilla bone of the face that allows nerves and blood to reach the skin.<\/p>\n<p class=\"import-Normal\"><strong>Insular dwarfing<\/strong>: A form of dwarfism that occurs when a limited geographic region, such as an island, causes a large-bodied animal to be selected for a smaller body size.<\/p>\n<p class=\"import-Normal\"><strong>Interglacial<\/strong>: A warmer period between two glacial time periods.<\/p>\n<p class=\"import-Normal\"><strong>Levallois technique<\/strong>: A distinctive technique of stone tool manufacturing used by Archaic <em>Homo sapiens<\/em>, including Neanderthals. The technique involves the preparation of a core and striking edges off in a regular fashion around the core. Then a series of similarly sized pieces can be removed, which can then be turned into different tools.<\/p>\n<p class=\"import-Normal\"><strong>Midfacial prognathism<\/strong>: A forward projection of the nose or the middle facial region. Usually associated with Neanderthals.<\/p>\n<p class=\"import-Normal\"><strong>Mousterian tools<\/strong>: The stone tool industry of Neanderthals and their contemporaries in Africa and Western Asia. Mousterian tools are known for a diverse set of flake tools, which is different from the large bifacial tools of the Acheulean industry.<\/p>\n<p class=\"import-Normal\"><strong>Nasal aperture<\/strong>: The opening for the nose visible on a skull. Often pear- or heart-shaped.<\/p>\n<p class=\"import-Normal\"><strong>Occipital bun<\/strong>: A prominent bulge or projection on the back of the skull, specifically the occipital bone. This is a feature present only on Neanderthal skulls.<\/p>\n<p class=\"import-Normal\"><strong>Ochre<\/strong>: A natural clay pigment mixed with ferric oxide and clay and sand. Ranges in colour from brown to red to orange.<\/p>\n<p class=\"import-Normal\"><strong>Retracted face<\/strong>: A face that is flatter.<\/p>\n<p class=\"import-Normal\"><strong>Retromolar gap<\/strong>: A space behind the last molar and the end of the jaw. This is a feature present only on Neanderthals. It also occurs through cultural modification in modern humans who have had their third molars, or wisdom teeth, removed.<\/p>\n<h2 class=\"import-Normal\">For Further Exploration<\/h2>\n<p><a href=\"https:\/\/www.amnh.org\/exhibitions\/permanent-exhibitions\/anne-and-bernard-spitzer-hall-of-human-origins\" target=\"_blank\">Anne and Bernard Spitzer Hall of Human Origins<\/a>\u2014American Museum of Natural History.<\/p>\n<p>\u201cDawn of Humanity,\u201d PBS documentary, 2015<\/p>\n<p><a href=\"https:\/\/www.ted.com\/talks\/svante_paeaebo_dna_clues_to_our_inner_neanderthal?language=en\" target=\"_blank\">\u201cDNA Clues to Our Inner Neanderthal,\u201d<\/a> TED Talk by Svante P\u00e4\u00e4bo, 2011.<\/p>\n<p>\u201cThe Dirt\u201d Podcast, Episode 30, <a href=\"https:\/\/thedirtpod.com\/episodes\/\/episode-30-the-human-family-tree-shrub-crabgrass-tumbleweed-part-3\" target=\"_blank\">\u201cThe Human Family Tree (Shrub? Crabgrass? Tumbleweed?), Part 3: Very Humany Indeed\u201d<\/a>.<\/p>\n<p class=\"import-Normal\"><a href=\"https:\/\/www.efossils.org\/page\/games-and-activities\" target=\"_blank\">eFossil Games and Activities<\/a><\/p>\n<p>Frank, Rebecca. 2021. \u201cThe Genus Homo.\u201d In <a href=\"https:\/\/explorations.americananthro.org\/index.php\/lab-and-activities-manual\/\" target=\"_blank\"><em>Explorations: Lab and Activity Manual, <\/em><\/a>edited by Beth Shook, Katie Nelson, Kelsie Aguilera, and Lara Braff. Arlington, VA: American Anthropological Association.<\/p>\n<p><a href=\"https:\/\/humanorigins.si.edu\/research\/asian-research-projects\/hobbits-flores-indonesia.\" target=\"_blank\">Hobbits on Flores, Indonesia<\/a> - Smithsonian Human Origins.<\/p>\n<p><a href=\"https:\/\/evolution.berkeley.edu\/evo-news\/lumping-or-splitting-in-the-fossil-record\/\" target=\"_blank\">Lumping or Splitting in the Fossil Record<\/a> - UC Berkeley Understanding Evolution.<\/p>\n<p><a href=\"https:\/\/www.eva.mpg.de\/genetics\/neandertals-and-more\/overview\/\" target=\"_blank\">Neandertals and More<\/a>\u00a0- Max Planck Institute for Evolutionary Anthropology.<\/p>\n<p><a href=\"https:\/\/www.sapiens.org\/biology\/neanderthal-anatomy\/?fbclid=IwAR2Bcff1GVkTLnbCR58JAWiJzkk-Ell7zL0FUddf1HNAX6RDAZxbqh1zWoI\" target=\"_blank\">Neanderthals: Body of Evidence<\/a> - SAPIENS.<\/p>\n<p>Perash, Rose L., and Kristen A. Broehl. 2021. \u201cHominin Review: Evolutionary Trends.\u201d In <a href=\"https:\/\/explorations.americananthro.org\/index.php\/lab-and-activities-manual\/.\" target=\"_blank\"><em>Explorations: Lab and Activity Manual<\/em><\/a>, edited by Beth Shook, Katie Nelson, Kelsie Aguilera, and Lara Braff. Arlington, VA: American Anthropological Association.<\/p>\n<p>Perkl, Bradley. \u201cBrain, Language, Lithics.\u201d In <a href=\"https:\/\/explorations.americananthro.org\/index.php\/lab-and-activities-manual\/.\" target=\"_blank\"><em>Explorations: Lab and Activity Manual<\/em><\/a>, edited by<em>.<\/em> Beth Shook, Katie Nelson, Kelsie Aguilera, and Lara Braff. CC BY-NC. Arlington, VA: American Anthropological Association.<\/p>\n<p><a href=\"https:\/\/humanorigins.si.edu\/evidence\/human-fossils\/shanidar-3-neanderthal-skeleton\" target=\"_blank\">Shanidar 3 - Neanderthal Skeleton<\/a> - Smithsonian Human Origins.<\/p>\n<p><a href=\"https:\/\/humanorigins.si.edu\/evidence\/human-fossils\/species\" target=\"_blank\">Species<\/a> - Smithsonian Human Origins.<\/p>\n<p><a href=\"https:\/\/www.facebook.com\/smithsonian.humanorigins\/\" target=\"_blank\">Smithsonian Human Origins Program Facebook page<\/a> (@smithsonian.humanorigins).<\/p>\n<p><a href=\"https:\/\/www.smithsonianmag.com\/science-nature\/bringing-human-evolution-life-180951155\/\" target=\"_blank\">Paleoartist Brings Human Evolution to Life<\/a> - Elisabeth Dayn\u00e9s.<\/p>\n<h2 class=\"import-Normal\">References<\/h2>\n<p>Ackermann, Rebecca R., Matthew L. 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L., B. B. Ha, S. J. Wang, Z. J. Chen, J. Y. Ge, H. Long, W. He, et al. 2018. \u201cThe Earliest Human Occupation of the High-Altitude Tibetan Plateau 40 Thousand to 30 Thousand Years Ago.\u201d <em>Science<\/em> 362 (6418): 1049\u20131051. <a class=\"rId177\" href=\"https:\/\/doi.org\/10.1126\/sciadv.add5582.\" target=\"_blank\">https:\/\/doi.org\/10.1126\/sciadv.add5582.<\/a><\/p>\n<p>Zeberg, Hugo, Mattias Jakobsson, &amp; Svante P\u00e4\u00e4bo. (2024). \u201cThe Genetic Changes That Shaped Neandertals, Denisovans, and Modern Humans.\u201d Cell 187, no. 5:1047\u20131058. <a href=\"https:\/\/doi.org\/10.1016\/j.cell.2023.12.029\" target=\"_blank\">https:\/\/doi.org\/10.1016\/j.cell.2023.12.029<\/a>.<\/p>\n<p class=\"import-Normal\">Zilh\u00e3o Jo\u00e3o, Diego E. Angelucci, Ernestina Badal-Garc\u00eda, Francesco d'Errico, Flor\u00e9al Daniel, Laure Dayet, Katerina Douka, et al. 2010. \u201cSymbolic Use of Marine Shells and Mineral Pigments by Iberian Neandertals.\u201d <em>Proceedings of the National Academy of Sciences<\/em> 107 (3): 1023\u20131028. <a class=\"rId178\" href=\"https:\/\/doi.org\/10.1073\/pnas.0914088107.\" target=\"_blank\">https:\/\/doi.org\/<\/a><a class=\"rId179\" href=\"https:\/\/doi.org\/10.1073\/pnas.0914088107.\" target=\"_blank\">10.1073\/pnas.0914088107.<\/a><\/p>\n<p class=\"import-Normal\">Zollikofer, Christopher Peter Edwards, and Marcia Silvia Ponce de Le\u00f3n. 2013. \u201cPandora\u2019s Growing Box: Inferring the Evolution and Development of Hominin Brains from Endocasts.\u201d Evolutionary Anthropology 22 (1): 20\u201333. <a class=\"rId180\" href=\"https:\/\/doi.org\/10.1002\/evan.21333.\" target=\"_blank\">https:\/\/doi.org\/10.1002\/evan.21333.<\/a><\/p>\n<h2>Acknowledgements<\/h2>\n<p class=\"import-Normal\">The authors would like to extend their thanks to Cassandra Gilmore and Anna Goldfield for thoughtful and insightful suggestions on the first edition of this chapter.<\/p>\n<\/div>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1695_1876\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1695_1876\"><div tabindex=\"-1\"><div class=\"__UNKNOWN__\">\n<div class=\"textbox\">\n<p>Learn more about <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/about-the-authors\/\">authors and editors<\/a>,<a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/student-contributors\/\"> Hess' student contributions<\/a>, and <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/versioning-history\/\">versioning history<\/a>.<\/p>\n<\/div>\n<div class=\"textbox textbox--learning-objectives\">\n<header class=\"textbox__header\">\n<h2 class=\"textbox__title\">Learning Objectives<\/h2>\n<\/header>\n<div class=\"textbox__content\">\n<ul>\n<li>Describe how early Pleistocene climate change influenced the evolution of the genus Homo.<\/li>\n<li>Identify the characteristics that define the genus Homo.<\/li>\n<li>Describe the skeletal anatomy of Homo habilis and Homo erectus based on the fossil evidence.<\/li>\n<li>Assess opposing points of view about how early Homo should be classified.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<p><span style=\"color: #000000\">The boy was no older than nine years when he perished by the swampy shores of the lake. After death, his slender, long-limbed body sank into the mud of the lake shallows. His bones fossilized and lay undisturbed for 1.5 million years. In the 1980s, fossil hunter Kamoya Kimeu, working on the western shore of Lake Turkana, Kenya, glimpsed a dark-coloured piece of bone eroding in a hillside. This small skull fragment led to the discovery of what is arguably the world\u2019s most complete early hominin fossil\u2014a youth identified as a member of the species <em>Homo erectus<\/em>. Now known as Nariokotome Boy, after the nearby lake village, the skeleton has provided a wealth of information about the early evolution of our own genus, <em>Homo <\/em>(see Figure 11.1). Today, a stone monument with an inscription in three languages\u2014English, Swahili, and the local Turkana language\u2014marks the site of this momentous fossil discovery.<\/span><\/p>\n<p><img class=\"aligncenter\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2023\/06\/image8-1.jpg\" alt=\"Front view of near-complete skeleton\" width=\"407\" height=\"407\" \/><\/p>\n<figure style=\"width: 405px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image13-1.jpg\" alt=\"Reconstructed head and shoulders of a young Homo erectus.\" width=\"405\" height=\"308\" \/><figcaption class=\"wp-caption-text\">Figure 11.1a-b: a. Skeleton of a young male Homo erectus known as \u201cNariokotome Boy\u201d; b. an artist\u2019s depiction of how he may have looked during his life. This is the most complete hominin fossil from this time period ever found. Credit: a.<a href=\"https:\/\/humanorigins.si.edu\/evidence\/human-fossils\/fossils\/knm-wt-15000\"> KNM-WT 15000 Turkana Boy Skeleton<\/a> by<a href=\"https:\/\/www.si.edu\/\"> Smithsonian<\/a> [exhibit:<a href=\"https:\/\/humanorigins.si.edu\/research\"> Human Evolution<\/a> Evidence, Human Fossils, Fossils, KNM-WT 15000] is<a href=\"https:\/\/www.si.edu\/termsofuse\/\"> copyrighted and used for educational and non-commercial purposes as outlined by the Smithsonian<\/a>. b. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Homo-erectus_Turkana-Boy_%28Ausschnitt%29_Fundort_Nariokotome,_Kenia,_Rekonstruktion_im_Neanderthal_Museum.jpg\">Homo-erectus Turkana-Boy (Ausschnitt) Fundort Nariokotome, Kenia, Rekonstruktion im Neanderthal Museum<\/a> by Neanderthal Museum is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/deed.en\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Chapter 10 described our oldest human ancestors, primarily members of the genus <em>Australopithecus<\/em>, who lived between 2 million and 4 million years ago. This chapter introduces the earliest members of the genus <em>Homo<\/em>, focusing on <em>Homo habilis<\/em> and <em>Homo erectus<\/em>.<\/span><\/p>\n<h2 class=\"import-Normal\"><span style=\"color: #000000\">Defining the Genus <em>Homo<\/em><\/span><\/h2>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Because Anthropology is fundamentally concerned with what makes us human, defining our own genus takes on special significance for anthropologists. Ever since scientists acknowledged the existence of extinct species of humans, they have debated which of them display sufficient \u201chumanness\u201d to merit classification in the genus <em>Homo<\/em>. When grouping species into a common genus, biologists consider criteria such as physical characteristics (morphology), evidence of recent common ancestry, and adaptive strategy (use of the environment). However, there is disagreement about which of those criteria should be prioritized, as well as how specific fossils should be interpreted in light of the criteria.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Nevertheless, there is general agreement that species classified as <em>Homo<\/em> should share characteristics that are broadly similar within our species. These include the following:<\/span><\/p>\n<ul>\n<li class=\"import-Normal\" style=\"background-color: transparent;text-align: left;text-indent: 18pt\"><span style=\"color: #000000\">a relatively large brain size<\/span><\/li>\n<li class=\"import-Normal\" style=\"background-color: transparent;text-align: left;text-indent: 18pt\"><span style=\"color: #000000\">a smaller and flatter face<\/span><\/li>\n<li class=\"import-Normal\" style=\"background-color: transparent;text-align: left;text-indent: 18pt\"><span style=\"color: #000000\">smaller jaws and teeth<\/span><\/li>\n<li class=\"import-Normal\" style=\"background-color: transparent;text-align: left;text-indent: 18pt\"><span style=\"color: #000000\">increased reliance on culture, particularly the use of stone tools, to exploit a greater diversity of environments (adaptive zone).<\/span><\/li>\n<\/ul>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Some researchers would include larger overall body size and limb proportions (longer legs\/shorter arms) in this list. While these criteria seem relatively clear-cut, evaluating them in the fossil record has proved more difficult, particularly for the earliest members of the genus. There are several reasons for this. First, many fossil specimens dating to this time period are incomplete and poorly preserved. Second, early <em>Homo<\/em> fossils appear quite variable in brain size, facial features, and teeth and body size, and there is not yet consensus about how to best make sense of this diversity. Finally, there is growing evidence that the evolution of the genus <em>Homo<\/em> proceeded in a mosaic pattern: in other words, these characteristics did not appear all at once in a single species; rather, they were patchily distributed in different species from different regions and time periods. Consequently, different researchers have come up with conflicting classification schemes depending on which criteria they think are most important.<\/span><\/p>\n<h2 class=\"import-Normal\"><span style=\"color: #000000\">Climate Change and Human Evolution<\/span><\/h2>\n<p class=\"import-Normal\"><span style=\"color: #000000\">A key goal in the study of human origins is to learn about the environmental pressures that may have shaped human evolution. As indicated in Chapter 8, scientists use a variety of techniques to reconstruct ancient environments. These include stable isotopes, core samples from oceans and lakes, windblown dust, analysis of geological formations and volcanoes, and fossils of ancient plant and animal communities. Such studies have provided valuable information about the environmental context of early <em>Homo<\/em>.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">The early hominin species covered in Chapter 10, such as <em>Ardipithecus ramidus<\/em> and <em>Australopithecus afarensis<\/em>, evolved during the late <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1404\">Pliocene<\/a><\/strong> epoch. The Pliocene (5.3 million to 2.6 million years ago) was marked by cooler and drier conditions, with ice caps forming permanently at the poles. Still, Earth\u2019s climate during the Pliocene was considerably warmer and wetter than at present.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">The subsequent <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1549\">Pleistocene<\/a> <\/strong>epoch (2.6 million years to 11,000 years ago) ushered in major environmental change. The Pleistocene is popularly referred to as the Ice Age. Since the term \u201cIce Age\u201d tends to conjure up images of glaciers and woolly mammoths, one would naturally assume that this was a period of uniformly cold climate around the globe. But this is not actually the case. Instead, climate became much more variable, cycling abruptly between warm\/wet (interglacial) and cold\/dry (glacial) cycles. These patterns were influenced by changes in Earth\u2019s elliptical orbit around the sun. As is shown in Figure 11.2, each cycle averaged about 41,000 years during the early Pleistocene; the cycles then lengthened to about 100,000 years starting around 1.25 million years ago. Since mountain ranges, wind patterns, ocean currents, and volcanic activity can all influence climate patterns, there were wide-ranging regional and local effects.<\/span><\/p>\n<figure style=\"width: 655px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image7-3.png\" alt=\"Graph depicts five million years of climate change from sediment cores.\" width=\"655\" height=\"197\" \/><figcaption class=\"wp-caption-text\">Figure 11.2: Temperature estimates during the last five million years, extrapolated from deep-sea core data. Lower temperatures and increased temperature oscillations start at 2.6 million years ago. Glacial\/interglacial cycles during the early part of the epoch are shorter, each averaging about 41,000 years. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Five_Myr_Climate_Change.png\">Five Myr Climate Change<\/a> by<a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Dragons_flight\"> Dragons flight<\/a> (Robert A. Rohde), based on data from Lisiechi and Raymo (2005), is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\"> CC BY-SA 3.0 License.<\/a><\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Data on ancient geography and climate help us understand how our ancestors moved and migrated to different parts of the world\u2014as well as the constraints under which they operated. When periods of global cooling dominated, sea levels were lower as more water was captured as glacial ice. This exposed continental margins and opened pathways between land masses. During glacial periods, the large Indonesian islands of Sumatra, Java, and Borneo were connected to the Southeast Asian mainland, while New Guinea was part of the southern landmass of greater Australia. There was a land bridge connection between Britain and continental Europe, and an icy, treeless plain known as Beringia connected Northern Asia and Alaska. At the same time, glaciation made some northern areas inaccessible to human habitation. For example, there is evidence that hominin species were in Britain 950,000 years ago, but it does not appear that Britain was continuously occupied during this period. It is speculated that these early humans may have died out or been forced to abandon the region during glacial periods.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">In Africa, paleoclimate research has determined that grasslands (shown in Figure 11.3) expanded and shrank multiple times during this period, even as they expanded over the long term (deMenocal 2014). From studies of fossils, paleontologists have been able to reconstruct Pleistocene animal communities and to consider how they were affected by the changing climate. Among the African animal populations, the number of grazing animal species such as antelope increased. Although the African and Eurasian continents are connected by land, the Sahara desert and the mountainous topography of North Africa serve as natural barriers to crossing. But the fossil record shows that at different times animal species have moved back and forth between Africa and Eurasia. During the early Pleistocene, there is evidence of African mammal species such as baboons, hippos, antelope, and African buffalo migrating out of Africa into Eurasia during periods of aridity (Belmaker 2010).<\/span><\/p>\n<figure style=\"width: 583px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image3-2.jpg\" alt=\"Dry grassy field with a few trees and mountains in the far distance.\" width=\"583\" height=\"406\" \/><figcaption class=\"wp-caption-text\">Figure 11.3: A savanna grassland in East Africa. Habitats such as this were becoming increasingly common during the Pleistocene. Credit: <a href=\"https:\/\/www.flickr.com\/photos\/ilri\/5130992564\">Savanna grasslands of East Africa<\/a> by<a href=\"https:\/\/www.flickr.com\/photos\/ilri\/\"> International Livestock Research Institute (ILRI)\/Elsworth<\/a> is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\"> CC BY-NC-SA 2.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">This changing environment was undoubtedly challenging for our ancestors, but it offered new opportunities to make a living. It is theorized that one solution adopted by some hominins was to specialize in feeding on the new types of plants growing in this landscape. The robust australopithecines (described in Chapter 10) likely developed their large molar teeth with thick enamel in order to exploit this particular dietary niche.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Members of the genus <em>Homo <\/em>took a different route. Faced with the unstable African climate and shifting landscape, it is proposed that they evolved bigger brains that might have enabled them to rely on cultural solutions such as crafting stone tools that opened up new foraging opportunities. This strategy of behavioural flexibility might have served them well during this unpredictable time and may have led to new innovations such as increased meat-eating, cooperative hunting, and the exploitation of new environments outside Africa. <\/span><\/p>\n<h2 class=\"import-Normal\"><span style=\"color: #000000\"><em>Homo habilis<\/em>: The Earliest Members of Our Genus<\/span><\/h2>\n<p class=\"import-Normal\"><span style=\"color: #000000\"><em>Homo habilis<\/em> has traditionally been considered the earliest species placed in the genus <em>Homo<\/em>. However, as we will see, there is substantial disagreement among paleoanthropologists about the fossils classified as <em>Homo habilis<\/em>, including whether they come from a single species or multiple, or even whether they should be part of the genus <em>Homo <\/em>at all.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\"><em>Homo habilis<\/em> has a somewhat larger brain size\u2014an average of 650 cubic centimetres (cc)\u2014compared to <em>Australopithecus<\/em> with less than 500 cc. Additionally, the skull is more rounded and the face less prognathic. However, the postcranial remains show a body size and proportions similar to <em>Australopithecus<\/em>.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Known dates for fossils identified as <em>Homo habilis<\/em> range from about 2.5 million years ago to 1.7 million years ago. Recently, a partial lower jaw dated to 2.8 million years from the site of Ledi-Gararu in Ethiopia has been tentatively identified as belonging to the genus <em>Homo<\/em> (Villmoare et al. 2015). If this classification holds up, it would push the origins of our genus back even further.<\/span><\/p>\n<figure style=\"width: 554px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image16.jpg\" alt=\"Africa map with South Africa, Tanzania, Kenya, and Ethiopia shaded.\" width=\"554\" height=\"717\" \/><figcaption class=\"wp-caption-text\">Figure 11.4: Map showing major sites where <em>Homo habilis<\/em> fossils have been found. Ledi-Geraru is located in Ethiopia, Koobi Fora and Lake Turkana Basin are located in Kenya, the Olduvai Gorge is located in Tanzania, and Tuang, Malapa, Rising Star and Sterkfontein are located in South Africa. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-15\/\">Homo habilis site map (Figure 10.4)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Chelsea Barron at<a href=\"https:\/\/www.csuchico.edu\/geop\/geoplace\/index.shtml\"> GeoPlace, California State University, Chico<\/a> is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\"> CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\"><span style=\"color: #000000\">The first fossils to be named <em>Homo habilis<\/em> were discovered at the site of Olduvai Gorge in Tanzania, East Africa, by members of a team led by Louis and Mary Leakey (Figure 11.4). The Leakey family had been conducting fieldwork in the area since the 1930s and had discovered other hominin fossils at the site, such as the robust <em>Paranthropos boisei<\/em>. The key specimen, a juvenile individual, was actually found by their 20-year-old son Jonathan Leakey. Louis Leakey invited South African paleoanthropologist Philip Tobias and British anatomist John Napier to reconstruct and analyse the remains. The fossil of the juvenile shown in Figure 11.5 (now known as OH-7) consisted of a lower jaw, parts of the parietal bones of the skull, and some hand and finger bones. The fossil was dated by potassium-argon dating to about 1.75 million years. In 1964, the team published their findings in the scientific journal <em>Nature <\/em>(Leakey et al. 1964)<em>. <\/em>As described in the publication, the new fossils had smaller molar teeth that were less \u201cbulgy\u201d than australopithecine teeth. Although the primary specimen was not yet fully grown, an estimate of its anticipated adult brain size would make it somewhat larger-brained than australopithecines such as <em>Austalopithecus africanus<\/em>. The hand bones were capable of a precision grip like a human\u2019s hand. This increased the likelihood that stone tools found earlier at Olduvai Gorge were made by this group of hominins. Based on these findings, the authors inferred that it was a new species that should be classified in the genus <em>Homo<\/em>. They gave it the name <em>Homo habilis<\/em>, meaning \u201chandy\u201d or \u201cskilled.\u201d<\/span><\/p>\n<\/div>\n<figure id=\"attachment_316-3\" aria-describedby=\"caption-attachment-316-3\" style=\"width: 641px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-316\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/10.5.jpg\" alt=\"Two lateral right views of skulls and a jaw with blackened teeth.\" width=\"641\" height=\"214\" \/><figcaption id=\"caption-attachment-316-3\" class=\"wp-caption-text\">Figure 11.5a-c: Homo habilis fossil specimens. From left to right they are: a. lateral right view of OH-24 (found at Olduvai Gorge), b. lateral right view of KNM-ER-1813 (from Koobi Fora, Kenya), and c. the jaw of OH-7, which was the type specimen found in 1960 at Olduvai Gorge, Tanzania. Credit: a. <a href=\"https:\/\/efossils.org\/page\/boneviewer\/Homo%20habilis\/OH%2024\">Homo habilis: OH 24 lateral right view<\/a> by \u00a9<a href=\"https:\/\/www.efossils.org\/\">eFossils<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\">CC BY-NC-SA 2.0 License<\/a> and is <a href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\">used as outlined by eFossils<\/a>. b. <a href=\"https:\/\/www.efossils.org\/page\/boneviewer\/Homo%20habilis\/KNM-ER%201813\">Homo habilis: KNM-ER 1813 lateral right view<\/a> by \u00a9<a href=\"https:\/\/www.efossils.org\/\">eFossils<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\">CC BY-NC-SA 2.0 License<\/a> and is <a href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\">used as outlined by eFossils<\/a>. c. <a href=\"https:\/\/boneclones.com\/product\/homo-habilis-oh-7-jaw-KO-196\">Homo habilis OH 7 Jaw<\/a> by<a href=\"https:\/\/boneclones.com\/\"> \u00a9BoneClones<\/a> is used by permission and available here under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\"> CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<div class=\"__UNKNOWN__\">\n<h3 class=\"import-Normal\"><span style=\"color: #000000\"><strong>Controversies over the Classification of <\/strong><strong><em>Homo habilis<\/em><\/strong><em><br style=\"clear: both\" \/><\/em><\/span><\/h3>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Since its initial discovery, many more Homo habilis were discovered in East and South African sites during the 1970s and 1980s (Figure 11.6). As more fossils joined the ranks of <em>Homo habilis<\/em>, several trends became apparent. First, the fossils were quite variable. While some resembled the fossil specimen first published by Leakey and colleagues, others had larger cranial capacity and tooth size. A well-preserved fossil skull from East Lake Turkana labeled KNM-ER-1470 displayed a larger cranial size along with a strikingly wide face. The diversity of the <em>Homo habilis<\/em> fossils prompted some scientists to question whether they displayed too much variation to all belong to the same species. They proposed splitting the fossils into at least two groups. The first group resembling the original small-brained specimen would retain the species name <em>Homo habilis<\/em>; the second group consisting of the larger-brained fossils such as KNM-ER-1470 would be assigned the new name of <em>Homo rudolfensis <\/em>(see Figure 11.7). Researchers who favoured keeping all fossils in <em>Homo habilis<\/em> argued that sexual dimorphism, adaptation to local environments, or<strong> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1566\">developmental plasticity<\/a><\/strong> could be the cause of the differences. For example, modern human body size and body proportions are influenced by variations in climates and nutritional circumstances.<\/span><\/p>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 467.5pt;height: 367px\">\n<caption>Figure 11.6: Key Homo habilis fossil locations and the corresponding fossils and dates. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-15\/\">Homo habilis table (Figure 10.6)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Bonnie Yoshida-Levine is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\"> CC BY-NC 4.0 License<\/a>.<\/caption>\n<thead>\n<tr style=\"height: 0\">\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 60px;width: 130.2px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Location of Fossils<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 60px;width: 52.7px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Dates<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 60px;width: 320.9px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong><br \/>\nDescription <\/strong><\/span><\/p>\n<p>&nbsp;<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 61px;width: 130.2px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Ledi-Gararu, Ethiopia<\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 61px;width: 52.7px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">2.8 mya<\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 61px;width: 320.9px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Partial lower jaw with evidence of both <em>Australopithecus<\/em> and <em>Homo<\/em> traits; tentatively considered oldest Early <em>Homo<\/em> fossil evidence.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 77px;width: 130.2px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Olduvai Gorge, Tanzania<\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 77px;width: 52.7px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">1.7 mya to 1.8 mya<\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 77px;width: 320.9px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Several different specimens classified as Homo habilis, including the type specimen found by Leakey, a relatively complete foot, and a skull with a cranial capacity of about 600 cc.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 93px;width: 130.2px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Koobi Fora, Lake Turkana Basin, Kenya<\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 93px;width: 52.7px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">1.9 mya<\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 93px;width: 320.9px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Several fossils from the Lake Turkana basin show considerable size differences, leading some anthropologists to classify the larger specimen (KNM-ER-1470) as a separate species,<em> Homo rudolfensis<\/em>.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 61px;width: 130.2px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Sterkfontein and other possible South African cave sites<\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 61px;width: 52.7px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">about 1.7 mya<\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"padding: 0pt 5.4pt;border: 0.5pt solid #000000;height: 61px;width: 320.9px\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">South African caves have yielded fragmentary remains identified as <em>Homo habilis<\/em>, but secure dates and specifics about the fossils are lacking.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr style=\"height: 15px\">\n<td style=\"height: 15px;width: 132.133px\"><\/td>\n<td style=\"height: 15px;width: 54.6333px\"><\/td>\n<td style=\"height: 15px;width: 322.333px\"><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<figure style=\"width: 228px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image10-1.jpg\" alt=\"Front view of black and white skull, missing lower jawbone.\" width=\"228\" height=\"228\" \/><figcaption class=\"wp-caption-text\">Figure 11.7: Cast of the Homo habilis cranium KNM-ER-1470. This cranium has a wide, flat face, larger brain size, and larger teeth than other Homo habilis fossils, leading some scientists to give it a separate species name, Homo rudolfensis. Credit: <a href=\"https:\/\/boneclones.com\/product\/homo-rudolfensis-skull-knm-er-1470-BH-013\">Homo rudolfensis Cranium KNM-ER 1470<\/a> by<a href=\"https:\/\/boneclones.com\/\"> \u00a9BoneClones<\/a> is used by permission and available here under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\"> CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Given the incomplete and fragmentary fossil record from this time period, it is not surprising that classification has proved contentious. As a scholarly consensus has not yet emerged on the classification status of early <em>Homo<\/em>, this chapter makes use of the single (inclusive) <em>Homo habilis<\/em> species designation.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">There is also disagreement on whether <em>Homo habilis<\/em> legitimately belongs in the genus <em>Homo<\/em>. Most of the fossils first classified as <em>Homo habilis<\/em> were skulls and teeth. When arm, leg, and foot bones were later found, making it possible to estimate body size, the specimens turned out to be quite small in stature with long arms and short legs. Analysis of the relative strength of limb bones suggested that the species, though bipedal, was much more adapted to arboreal climbing than <em>Homo erectus<\/em> and <em>Homo sapiens <\/em>(Ruff 2009). This has prompted some scientists to assert that <em>Homo habilis<\/em> behaved more like an australopithecine\u2014with a shorter gait and the ability to move around in the trees (Wood and Collard 1999). They were also skeptical of the claim that the brain size of <em>Homo habilis<\/em> was much larger than that of <em>Australopithecus<\/em>. They have proposed reclassifying some or all of the <em>Homo habilis<\/em> fossils into the genus <em>Australopithecus<\/em>, or even placing them into a newly created genus (Wood 2014).<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Other scholars have interpreted the fossil evidence differently. A recent reanalysis of <em>Homo habilis\/rudolfensis<\/em> fossils concluded that they sort into the genus <em>Homo<\/em> rather than <em>Australopithecus <\/em>(see Hominin Species Summaries at chapter end). In particular, statistical analysis performed indicates that the <em>Homo habilis<\/em> fossils differ significantly in average cranial capacity from the australopithecines. They also note that some australopithecine species such as the recently discovered <em>Australopithecus sediba<\/em> have relatively long legs, so body size may not have been as significant as brain- and tooth-size differences (Anton et al. 2014).<\/span><\/p>\n<div class=\"textbox\">\n<h2 class=\"import-Normal\"><span style=\"color: #000000\">Special Topic: Kamoya Kimeu<\/span><\/h2>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Kamoya Kimeu (1938\u20132022) is arguably the most prolific fossil hunter in the history of paleoanthropology (Figure 11.8). In addition to his many decades of work as a field excavator and project supervisor in East Africa, he also trained field workers and scholars and has served as curator for prehistoric sites for the National Museum of Kenya.<\/span><\/p>\n<figure style=\"width: 228px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image4-1.jpg\" alt=\"Man smiling at camera with lake and mountain in the background.\" width=\"228\" height=\"351\" \/><figcaption class=\"wp-caption-text\">Figure 11.8: Kamoya Kimeu (1938-2022). Credit: Photograph of Kamoya Kimeu by \u00a9Dr. Mark Teaford is used by permission.<\/figcaption><\/figure>\n<p><span style=\"color: #000000\">Kamoya Kimeu was born in 1938 in rural southeastern Kenya. Despite a formal education that did not go past the sixth grade, he had an aptitude for languages and familiarity with the plants and animals in the East African bush that led him to a job in Tanzania as a field excavator for Louis and Mary Leakey in 1960. In the years that followed, Kimeu found dozens of major hominin fossils. These included a <em>Paranthropus boisei <\/em>mandible at Olduvai Gorge, <em>Homo habilis <\/em>specimen KNM-ER-1813 from the Turkana Basin (shown in Figure 11.5), and a key early modern<em> Homo sapiens<\/em> fossil from the Omo Valley, Ethiopia. Kimeu\u2019s most famous fossil discovery was the skeleton of a young <em>Homo erectus<\/em> by the Nariokotome river bed in 1984. This finding was highly significant because it was a nearly complete early hominin skeleton and provided insight into child development within this species. In recognition of his work, Kimeu was awarded the National Geographic Society La Gorce Medal by U.S. President Ronald Reagan in 1985.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Traditionally, there has been a divide between African field workers and foreign research scientists, who would typically conduct seasonal field work in Africa, then travel back to their home institutions to publish their findings. Although Kimeu received widespread acclaim for the Nariokotome discovery, as well as a personal acknowledgement in the publication of the find in the journal <em>Nature<\/em>, he was not credited as an author. More recently, Kimeu\u2019s intellectual contributions to the field of paleoanthropology have been recognized. In 2021, he received an honorary doctorate degree from Case Western Reserve University in Ohio. Kimeu\u2019s most lasting legacy may be his mentorship of countless field workers and students. Today, there are a small but growing number of Black African paleoanthropologists taking on principal roles in the science of human origins.<\/span><\/p>\n<h2 class=\"import-Normal\"><span style=\"color: #000000\"><em>Homo habilis<\/em> Culture and Lifeways<br \/>\n<\/span><\/h2>\n<h3 class=\"import-Normal\"><span style=\"color: #000000\"><strong>Early Stone Tools<\/strong><\/span><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">It is theorized that the larger brains and smaller teeth of early <em>Homo <\/em>are linked to a different adaptive strategy than that of earlier hominins: one dependent on modifying rocks to make stone tools and exploit new food sources. As discussed in Chapter 10, the 3.3-million-year-old stone tools from the Lomekwi 3 site in Kenya were made by earlier hominin species than <em>Homo<\/em>. However, stone tools become more frequent at sites dating to about 2 million years ago, the time of <em>Homo habilis <\/em>(Roche et al. 2009). This suggests that these hominins were increasingly reliant on stone tools to make a living.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Stone tools are assigned a good deal of importance in the study of human origins. Examining the form of the tools, the raw materials selected, and how they were made and used can provide insight into the thought processes of early humans and how they modified their environment in order to survive. Paleoanthropologists have traditionally classified collections of stone tools into industries, based on their form and mode of manufacture. There is not an exact correspondence between a tool industry and a hominin species; however, some general associations can be made between tool industries and particular hominins, locations, and time periods.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">The <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1394\">Oldowan<\/a><\/strong> tool industry is named after the site of Olduvai Gorge in Tanzania where the tools were first discovered. The time period of the Oldowan is generally estimated to be 2.5 mya to 1.6 mya. The tools of this industry are described as \u201cflake and chopper\u201d tools\u2014the choppers consisting of stone cobbles with a few flakes struck off them (Figure 11.9). To a casual observer, these tools might not look much different from randomly broken rocks. However, they are harder to make than their crude appearance suggests. The rock selected as the core must be struck by the rock serving as a hammerstone at just the right angle so that one or more flat flakes are removed. This requires selecting rocks that will fracture predictably instead of chunking, as well as the ability to plan ahead and envision the steps needed to create the finished product. The process leaves both the core and the flakes with sharp cutting edges that can be used for a variety of purposes.<\/span><\/p>\n<figure style=\"width: 505px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image11-1-1.png\" alt=\"Three stones with chunks missing from the tops and sides.\" width=\"505\" height=\"281\" \/><figcaption class=\"wp-caption-text\">Figure 11.9: Drawing of an Oldowan-style tool. This drawing shows a chopper; the flakes removed from the cores functioned as cutting tools. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Chopping_tool.gif\">Chopping tool<\/a> by Jos\u00e9-Manuel Benito \u00c1lvarez is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.5\/legalcode\">CC BY-SA 2.5 License<\/a>.<\/figcaption><\/figure>\n<h3 class=\"import-Normal\"><span style=\"color: #000000\"><strong>Stone Tool Use and the Diet of Early <\/strong><strong><em>Homo<\/em><\/strong><\/span><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">What were the hominins doing with the tools? One key activity seems to have been butchering animals. Studies of animal bones at the site show cut marks on bones, and leg bones are often cracked open, suggesting that they were extracting the marrow from the bone cavities. It is interesting to consider whether the hominins hunted these animals or acquired them through other means. The butchered bones come from a variety of African mammals, ranging from small antelope to animals as big as wildebeest and elephants! It is difficult to envision slow, small-bodied <em>Homo habilis<\/em> with their Oldowan tools bringing down such large animals. One possibility is that the hominins were scavenging carcasses from lions and other large cats. Paleoanthropologist Robert Blumenschine has investigated this hypothesis by observing the behaviour of present-day animal carnivores and scavengers on the African savanna. When lions abandon a kill after eating their fill, scavenging animals arrive almost immediately to pick apart the carcass. By the time slow-footed hominins arrived on the scene, the carcass would be mostly stripped of meat. However, if hominins could use stone tools to break into the leg bone cavities, they could get to the marrow, a fatty, calorie-dense source of protein (Blumenschine et al. 1987). Reconstructing activities that happened millions of years ago is obviously a difficult undertaking, and paleoanthropologists continue to debate whether scavenging or hunting was more commonly practiced during this time.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Regardless of how they were acquiring the meat, these activities suggest an important dietary shift from the way that the australopithecines were eating. The Oldowan toolmakers were exploiting a new ecological niche that provided them with more protein and calories. And it was not just limited to meat-eating\u2014stone tool use could have made available numerous other subsistence opportunities. A study of microscopic wear patterns on a sample of Oldowan tools indicates that they were used for processing plant materials such as wood, roots or tubers, and grass seeds and stems (Lemorini et al. 2014). In fact, it has been pointed out that the Oldowan toolmakers\u2019 cutting ability (whether for the purposes of consuming meat and plants or for making tools, shelters, or clothing) represents a new and unique innovation, never seen before in the natural world (Roche et al. 2009).<\/span><\/p>\n<h2 class=\"import-Normal\"><span style=\"color: #000000\"><em>Homo erectus<\/em>: Biological and Cultural Innovations<\/span><\/h2>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Two million years ago, a new hominin appeared on the scene. Known as <em>Homo erectus<\/em>, the prevailing scientific view was that this species was much more like us. These hominins were equipped with bigger brains and large bodies with limb proportions similar to our own. Perhaps most importantly, their way of life is now one that is recognizably human, with more advanced tools, hunting, use of fire, and colonizing new environments outside of Africa.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">As will be apparent below, new data suggests that the story is not quite as simple. The fossil record for <em>Homo erectus<\/em> is much more abundant than that of <em>Homo habilis<\/em>, but it is also more complex and varied\u2014both with regard to the fossils as well as the geographic context in which they are found. <\/span><\/p>\n<h3 class=\"import-Normal\"><span style=\"color: #000000\"><strong><em>Homo erectus<\/em><\/strong><strong> Anatomy<\/strong><\/span><\/h3>\n<figure style=\"width: 289px\" class=\"wp-caption alignright\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image6-2.png\" alt=\"Lateral view of skull with large brow ridges.\" width=\"289\" height=\"289\" \/><figcaption class=\"wp-caption-text\">Figure 11.10: Replica of Homo erectus from Java, Indonesia. This cranium (known as Sangiran 17) dates to approximately 1.3 million to 1 million years ago. Note the large brow ridges and the occipital torus that gives the back of the skull a squared-off appearance. Credit: <a href=\"https:\/\/www.efossils.org\/page\/boneviewer\/Homo%20erectus\/Sangiran%2017\">Homo erectus: Sangiran 17 lateral left view<\/a>\u00a0 by \u00a9<a href=\"https:\/\/www.efossils.org\/\">eFossils<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\">CC BY-NC-SA 2.0 License<\/a> and is <a href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\">used as outlined by eFossils<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Compared to <em>Homo habilis<\/em>, <em>Homo erectus<\/em> showed increased brain size, smaller teeth, and a larger body. However, it also displayed key differences from later hominin species including our own. Although the head of <em>Homo erectus<\/em> was less ape-like in appearance than the australopithecines, it did not resemble modern humans (Figure 11.10). Compared to <em>Homo habilis<\/em>, <em>Homo erectus<\/em> had a larger brain size: an average of about 900 cc compared to 650 cc to 750 cc. Instead of a rounded shape like our skulls, the <em>erectus <\/em>skull was long and low like a football, with a receding forehead, and a horizontal ridge called an <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1552\">occipital torus<\/a><\/strong> that gave the back of the skull a squared-off appearance. The cranial bones are thicker than those of modern humans, and some <em>Homo erectus<\/em> skulls have a slight thickening along the sagittal suture called a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1553\">sagittal keel<\/a><\/strong>. Large, shelf-like brow ridges hang over the eyes. The face shows less <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1554\"> prognathism<\/a><\/strong>, and the back teeth are smaller than those of <em>Homo habilis. <\/em>Instead of a pointed chin, like ours, the mandible of <em>Homo erectus<\/em> recedes back.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Apart from these features, there is significant variation among <em>Homo <\/em><em>erectus<\/em> fossils from different regions. Scientists have long noted differences between the fossils from Africa and those from Indonesia and China. For example, the Asian fossils tend to have a thicker skull and larger brow ridges than the African specimens, and the sagittal keel described above is more pronounced. <em>Homo erectus<\/em> fossils from the Republic of Georgia (described in the next section) also display distinctive characteristics. As with <em>Homo habilis<\/em>, this diversity has prompted a classification debate about whether or not <em>Homo erectus<\/em> should be split into multiple species. When African <em>Homo erectus<\/em> is characterized as a separate species, it is called <em>Homo ergaster<\/em>, while the Asian variant retains the <em>erectus <\/em>species name because it was discovered first. Here, the species name <em>Homo erectus<\/em> will be used for both variants.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\"><em>Homo erectus<\/em> was thought to have a body size and proportions more similar to modern humans. Unlike <em>Homo habilis<\/em> and the australopithecines, both of whom were small-statured with long arms and short legs, <em>Homo erectus<\/em> shows evidence of being fully committed to life on the ground. This meant long, powerfully muscled legs that enabled these hominins to cover more ground efficiently. Indeed, studies of the <em>Homo erectus<\/em> body form have linked several characteristics of the species to long-distance running in the more open savanna environment (Bramble and Lieberman 2004). Many experts think that hominins around this time had lost much of their body hair, were particularly efficient at sweating, and had darker-pigmented skin\u2014all traits that would support the active lifestyle of such a large-bodied hominin.<\/span><\/p>\n<div class=\"__UNKNOWN__\">\n<div class=\"textbox\">\n<h2 class=\"import-Normal\"><span style=\"color: #000000\">Special Topic: How We Became Hairless, Sweaty Primates<\/span><\/h2>\n<p class=\"import-Normal\"><span style=\"color: #000000\">As an anthropology instructor teaching human evolution, my students often ask me about human body hair: When did our ancestors lose it and why? It is assumed that our earliest ancestors were as hairy as modern-day apes. Yet, today, we lack thick hair on most parts of our bodies except in the armpits, pubic regions, and tops of our heads. Humans actually have about the same number of hair follicles per unit of skin as chimpanzees, but, the hairs on most of our body are so thin as to be practically invisible. When did we develop this peculiar pattern of hairlessness? Which selective pressures in our ancestral environment were responsible for this unusual characteristic?<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Many experts believe that the driving force behind our loss of body hair was the need to effectively cool ourselves. Along with the lack of hair, humans are also distinguished by being exceptionally sweaty: we sweat larger quantities and more efficiently than any other primate. Humans have a larger amount of eccrine sweat glands than other primates and these glands generate an enormous volume of watery sweat. Sweating produces liquid on the skin that cools the body off as it evaporates. It seems likely that hairlessness and sweating evolved together, as a recent DNA analysis has identified a shared genetic pathway between hair follicles and eccrine sweat gland production (Kamberov et al. 2015).<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Which particular environmental conditions led to such adaptations? In this chapter, we learned that the climate was a driving force behind many changes seen in the hominin lineage during the Pleistocene. At that time, the climate was increasingly arid and the forest canopy in parts of Africa was being replaced with a more open grassland environment, resulting in increased sun exposure for our ancestors. Compared to the earlier australopithecines, members of the genus <em>Homo<\/em> were also developing larger bodies and brains, starting to obtain meat by hunting or scavenging carcasses, and crafting sophisticated stone tools.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">According to Nina Jablonski, an expert on the evolution of human skin, the loss of body hair and increased sweating capacity are part of the package of traits characterizing the genus <em>Homo<\/em>. While larger brains and long-legged bodies made it possible for humans to cover long distances while foraging, this new body form had to cool itself effectively to handle a more active lifestyle. Preventing the brain from overheating was especially critical. The ability to keep cool may have also enabled hominins to forage during the hottest part of the day, giving them an advantage over savanna predators, like lions, that typically rest during this time (Jablonski 2010).<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">When did these changes occur? Although hair and soft tissue do not typically fossilize, several indirect methods have been used to explore this question. One method tracks a human skin colour gene. Since chimpanzees have light skin under their hair, it is probable that early hominins also had light skin colour. Apes and other mammals with thick fur coats have protection against the sun\u2019s rays. As our ancestors lost their fur, it is likely that increased melanin pigmentation was selected for as a way to shield our ancestors from harmful ultraviolet radiation. A recent genetic analysis determined that one of the genes responsible for melanin production originated about 1.2 million years ago (Rogers et al 2004).<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Another line of evidence tracks the coevolution of a rather unpleasant human companion\u2014the louse. A genetic study identified human body louse as the youngest of the three varieties of lice that infest humans, splitting off as a distinct variety around 70,000 years ago (Kittler et al. 2003). Because human body lice can only spread through clothing, this may have been about the time when humans started to regularly wear clothing. However, the split between human head and pubic lice is estimated to have occurred much earlier, about three million years ago (Bower 2003; Reed et al. 2007). When humans lost much of their body hair, lice that used to roam freely around the body were now confined to two areas: the head and pubic region. As a result of this separation, the lice population split into two distinct groups.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Other explanations have been suggested for the loss of human body hair. For example, being hairless makes it more difficult for skin parasites like lice, fleas, and ticks to live on us. Additionally, after bipedality evolved, hairless bodies would also make reproductive organs and female breasts more visible, suggesting that sexual selection may have played a role.<\/span><\/p>\n<\/div>\n<\/div>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Much of the information about the body form of <em>Homo erectus<\/em> comes from the Nariokotome fossil of the <em>Homo erectus<\/em> youth, described at the beginning of the chapter (see Figure 11.1). However, <em>Homo erectus<\/em> fossils are turning out to be more varied than previously thought. <em>Homo erectus <\/em>fossils from sites in Africa, as well as from Dmanisi, Georgia, show smaller body sizes than the Nariokotome boy. Even the Nariokotome skeleton itself has been reassessed: some now predict he would have been about 5 feet and 4 inches when fully grown rather than over 6 feet as initially hypothesized, although there is still disagreement about which measurement is more accurate. One explanation for the range of body sizes could be adaptation to a range of different local environments, just as humans today show reduced body size in poor nutritional environments (Anton and Snodgrass 2012).<\/span><\/p>\n<h3 class=\"import-Normal\"><span style=\"color: #000000\"><strong><em>Homo erectus<\/em><\/strong><strong> in Africa <\/strong><\/span><\/h3>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Although the earliest discoveries of <em>Homo erectus<\/em> fossils were from Asia, the greatest quantity and best-preserved fossils of the species come from East African sites. The earliest fossils in Africa identified as <em>Homo erectus <\/em>come from the East African site of Koobi Fora, around Lake Turkana in Kenya, and are dated to about 1.8 million years ago. Other fossil remains have been found in East African sites in Kenya, Tanzania, and Ethiopia. Other notable African <em>Homo erectus<\/em> finds are a female pelvis from the site of Gona, Ethiopia (Simpson et al. 2008), and a cranium with massive brow ridges from Olduvai Gorge known as Olduvai 9, thought to be about 1.4 million years old.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Until recently, <em>Homo erectus<\/em>\u2019 presence in southern Africa has not been well documented. However, work at the Drimolen cave site in South Africa has yielded new fossils of <em>Paranthropus robustus<\/em>, and the cranium of a 2\u20133 year old child tentatively identified as <em>Homo erectus<\/em>, dated to about 2 million years (Herries et al. 2020). If substantiated, this would be the oldest discovery to date of <em>Homo erectus<\/em> anywhere.<\/span><\/p>\n<h3 class=\"import-Normal\"><span style=\"color: #000000\"><strong>Regional Discoveries Outside Africa<\/strong><\/span><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">It is generally agreed that<em> Homo erectus<\/em> was the first hominin to migrate out of Africa and colonize Asia and later Europe (although recent discoveries in Asia may challenge this view). Key locations and discoveries of <em>Homo erectus<\/em> fossils, along with the fossils\u2019 estimated ages, are summarized in Figures 11.11 and 11.12.<\/span><\/p>\n<figure style=\"width: 594px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image17-3.jpg\" alt=\"World map with England, Spain, Georgia, Kenya, China, and Java shaded.\" width=\"594\" height=\"459\" \/><figcaption class=\"wp-caption-text\">Figure 11.11:\u00a0 Map showing the locations of Homo erectus fossils around Africa and Eurasia. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\">A full text description of this image is available<\/a>. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-15\/\">Homo erectus site map<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Chelsea Barron at<a href=\"https:\/\/www.csuchico.edu\/geop\/geoplace\/index.shtml\"> GeoPlace, California State University, Chico<\/a> is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\"> CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 467.5pt\">\n<caption>Figure 11.12: Regional comparisons of Homo erectus fossils. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-15\/\">Regional comparisons of Homo erectus fossils (Figure 10.12)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/caption>\n<thead>\n<tr style=\"height: 0\">\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Region<\/strong><\/span><\/p>\n<p>&nbsp;<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Sites<\/strong><\/span><\/p>\n<p>&nbsp;<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Dates<\/strong><\/span><\/p>\n<p>&nbsp;<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Significance of Fossils<\/strong><\/span><\/p>\n<p>&nbsp;<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">East Africa<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">East and West Lake Turkana, Kenya; Olduvai Gorge, Tanzania<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">1.8 to 1.4 mya<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Earliest evidence of <em>H. erectus<\/em>; significant variation in skull and facial features.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">South Africa<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Drimolen Cave, South Africa<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">2 mya<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Recent find of a 2\u20133 year old child would be oldest <em>H. erectus<\/em> anywhere to date.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Western<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Eurasia<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Dmanisi, Republic of Georgia<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">1.75 mya<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Smaller brains and bodies than <em>H. erectus<\/em> from other regions.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Western Europe<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Atapuerca, Spain (Sima del Elefante and Gran Dolina caves)<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">1.2 mya\u2013 400,000 ya<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Partial jaw from Atapuerca is oldest evidence of <em>H. erectus<\/em> in Western Europe.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Fossils from Gran Dolina (dated to about 800,000 years) sometimes referred to as <em>H. antecessor.<\/em><\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Indonesia<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Ngandong, Java; Sangiran, Java<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">1.6 mya<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Early dispersal of <em>H. erectus <\/em>to East Asia; Asian <em>H. erectus <\/em>features.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">China<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Zhoukoudian, China;<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Loess Plateau (Lantian)<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">780,000\u2013 400,000 ya;<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">2.1 mya<\/span><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"padding: 0pt 5.4pt 0pt 5.4pt;border: solid #000000 0.5pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Large sample of <em>H. erectus<\/em> fossils and artifacts.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Recent evidence of stone tools from Loess Plateau suggests great antiquity of <em>Homo<\/em> in East Asia.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<h4 class=\"import-Normal\"><span style=\"color: #000000\"><em>Indonesia<\/em><\/span><\/h4>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">The first discovery of<em> Homo erectus<\/em> was in the late 1800s in Java, Indonesia. A Dutch anatomist named Eugene Dubois searched for human fossils with the belief that since orangutans lived there, it might be a good place to look for remains of early humans. He discovered a portion of a skull, a femur, and other bone fragments on a riverbank. While the femur looked human, the top of the skull was smaller and thicker than that of a modern person. Dubois named the fossil <em>Pithecanthropus erectus<\/em> (\u201cupright ape-man\u201d), popularized in the media at the time as \u201cJava Man.\u201d After later discoveries of similar fossils in China and Africa, they were combined into a single species (retaining the <em>erectus<\/em> name) under the genus <em>Homo<\/em>.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Although <em>Homo erectus<\/em> has a long history in Indonesia, the region\u2019s geology has complicated the dating of fossils and sites. Fossils from the Sangiran Dome, Java, had previously been estimated to be as old as 1.8 million years, but scientists using new dating methods have arrived at a later date of about 1.3 mya (Matsu\u2019ura et al. 2020). On the recent end of the timeline, a cache of <em>H. erectus<\/em> fossils from the site of Ngandong in Java has yielded a surprisingly young date of 43,000 years, although a newer study with different dating methods concluded that they were between 117,000 to 108,000 years old (Rizal et al. 2020).<\/span><\/p>\n<h4 class=\"import-Normal\"><span style=\"color: #000000\"><em>China<\/em><\/span><\/h4>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">There is evidence of<em> Homo erectus <\/em>in China from several regions and time periods.<em> Homo erectus<\/em> fossils from northern China, collectively known as \u201cPeking Man,\u201d are some of the most famous human fossils in the world. Dated to about 400,000\u2013700,000 years ago, they were excavated from the site of Zhoukoudian, near the outskirts of Beijing. Hundreds of bones and teeth, including six nearly complete skulls, were excavated from a cave in the 1920s and 1930s. Much of the fossils\u2019 fame comes from the fact that they disappeared under mysterious circumstances. As Japan advanced into China during World War II, Chinese authorities, concerned for the security of the fossils, packed up the boxes and arranged for them to be transported to the United States. But in the chaos of the war, they vanished and were never heard about again. Fortunately, an anatomist named Frans Weidenreich had previously studied the bones and made casts and measurements of the skulls, so this valuable information was not lost. More recent excavations at Longgushan \u201cDragon Bone Cave\u201d at Zhoukoudian\u2014of tools, living sites, and food remains\u2014have revealed much about the lifestyle of <em>Homo erectus <\/em>during this time.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Despite this long history of research, China, compared to Africa, was perceived as somewhat peripheral to the study of hominin evolution. Although <em>Homo erectus<\/em> fossils have been found at several sites in China, with dates that make them comparable to those of Indonesian <em>Homo erectus<\/em>, none seemed to approximate the antiquity of African sites. The notable finds at sites like Nariokotome and Olorgesaille took centre stage during the 1970s and 1980s, as scientists focused on elucidating the species\u2019 anatomy and adaptations in its African homeland. In contrast, fewer research projects were focused on East Asian sites (Dennell and Roebroeks 2005; Qiu 2016).<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">However, isolated claims of very ancient hominin occupation kept cropping up from different locations in Asia. While some were dismissed because of problems with dating methods or stratigraphic context, the 2018 publication of the discovery of 2.1-million-year-old stone tools from China caught everyone\u2019s attention. Based on paleomagnetic techniques that date the associated soils and windblown dust, these tools indicate that hominins in Asia predated those from the Georgian site of Dmanisi by at least 300,000 years (Zhu et al. 2018). In fact, the tools are older than any <em>Homo erectus<\/em> fossils anywhere. Since no fossils were found with the tools, it isn\u2019t known which species made them, but it opens up the intriguing possibility that hominins could have migrated out of Africa earlier than <em>Homo erectus<\/em>. These new discoveries are shaking up previously held views of the East Asian human fossil record.<\/span><\/p>\n<h4 class=\"import-Normal\"><span style=\"color: #000000\"><em>Western Eurasia<\/em><\/span><\/h4>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">An extraordinary collection of fossils from the site of Dmanisi in the Republic of Georgia has revealed the presence of <em>Homo erectus<\/em> in Western Eurasia between 1.75 million and 1.86 million years ago. Dmanisi is located in the Caucasus mountains in Georgia. When archaeologists began excavating a medieval settlement near the town in the 1980s and came across the bones of extinct animals, they shifted their focus from the historic to the prehistoric era, but they probably did not anticipate going back quite so far in time. The first hominin fossils were discovered in the early 1990s, and since that time, at least five relatively well-preserved crania have been excavated.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">There are several surprising things about the Dmanisi fossils. Compared to African <em>Homo erectus,<\/em> they have smaller brains and bodies. However, despite the small brain size, they show clear signs of <em>Homo erectus<\/em> traits such as heavy brow ridges and reduced facial prognathism. Paleoanthropologists have pointed to some aspects of their anatomy (such as the shoulders) that appear rather primitive, although their body proportions seem fully committed to terrestrial bipedalism. One explanation for these differences could be that the Dmanisi hominins represent a very early form of <em>Homo erectus<\/em> that left Africa before increases in brain and body size evolved in the African population.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Second, although the fossils at this location are from the same geological context, they show a great deal of variation in brain size and in facial features. One skull (Skull 5) has a cranial capacity of only 550 cc, smaller than many <em>Homo habilis <\/em>fossils, along with larger teeth and a protruding face. Scientists disagree on what these differences mean. Some contend that the Dmanisi fossils cannot all belong to a single species because each one is so different. Others assert that the variability of the Dmanisi fossils proves that they, along with all early Homo fossils, including <em>H. habilis<\/em> and <em>H.<\/em><em>rudolfensis, <\/em>could <em>all <\/em>be grouped into <em>Homo erectus<\/em> (Lordkipanidze et al. 2013). Regardless of which point of view ends up dominating, the Dmanisi hominins are clearly central to the question of how to define the early members of the genus <em>Homo<\/em>.<\/span><\/p>\n<h4 class=\"import-Normal\"><span style=\"color: #000000\"><em>Europe<\/em><\/span><\/h4>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Until recently, there was scant evidence of any <em>Homo erectus<\/em> presence in Europe, and it was assumed that hominins did not colonize Europe until much later than East Asia or Eurasia. One explanation for this was that the harsh climate of Western Europe served as a barrier to settlement. However, recent fossil finds from Spain suggest that <em>Homo erectus<\/em> could have made it into Europe over a million years ago. In 2008 a mandible from the Atapuerca region in Spain was discovered, dating to about 1.2 million years ago. A more extensive assemblage of fossils from the site of Gran Dolina in Atapuerca have been dated to about 800,000 years ago. In England in 2013 fossilized hominin footprints of adults and children dated to 950,000 years ago were found at the site of Happisburgh, Norfolk, which would make them the oldest human footprints found outside Africa (Ashton et al. 2014).<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">At this time, researchers aren\u2019t in agreement as to whether the first Europeans belonged to <em>Homo erectus<\/em> proper or to a later descendent species. Some scientists refer to the early fossils from Spain by the species name <em>Homo antecessor<\/em>.<\/span><\/p>\n<\/div>\n<h2 class=\"__UNKNOWN__\"><span style=\"color: #000000\"><em>Homo erectus <\/em>Lifeways<\/span><\/h2>\n<div class=\"__UNKNOWN__\">\n<h3 class=\"import-Normal\"><span style=\"color: #000000\"><strong>Tool Technology: Acheulean Tool Industry<\/strong><\/span><\/h3>\n<figure style=\"width: 423px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image9-3.png\" alt=\"Front, back, side, and top views of oval-shaped stone core with chunks removed.\" width=\"423\" height=\"341\" \/><figcaption class=\"wp-caption-text\">Figure 11.13: Drawing of an Acheulean handaxe. This specimen is from Spain. When drawing a stone tool, artists typically show front and back faces, as well as top and side profiles. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Hand_axe_spanish.gif\">Hand axe spanish<\/a> by<a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Locutus_Borg\"> Jos\u00e9-Manuel Benito (user: Locutus Borg<\/a>) has been designated to the<a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/cc0\/\"> public domain (CC0)<\/a>.<\/figcaption><\/figure>\n<p>In early African sites associated with <em>Homo erectus<\/em>, stone tools such as flakes and choppers identified to the Oldowan Industry dominate. Starting at about 1.5 million years ago, some <em>Homo erectus<\/em> populations began making different forms of tools. These tools\u2014classified together as constituting the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1556\">Acheulean <\/a><\/strong> tool industry\u2014are more complex in form and more consistent in their manufacture. Unlike the Oldowan tools, which were cobbles modified by striking off a few flakes, Acheulean toolmakers carefully shaped both sides of the tool. This type of technique, known as bifacial flaking, requires more planning and skill on the part of the toolmaker; he or she would need to be aware of principles of symmetry when crafting the tool. One of the most common tool forms, the handaxe, is shown in Figure 11.13. As with the tool illustrated below, handaxes tend to be thicker at the base and then come to a rounded point at the tip. Besides handaxes, forms such as scrapers, cleavers, and flake tools are present at <em>Homo erectus<\/em> sites.<\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">One striking aspect of Acheulean tools is their uniformity. They are more standardized in form and mode of manufacture than the earlier Oldowan tools. For example, the aforementioned handaxes vary in size, but they are remarkably consistent in regard to their shape and proportions. They were also an incredibly stable tool form over time\u2014lasting well over a million years with little change.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Curiously, the Acheulean tools so prominent at African sites are mostly absent in <em>Homo erectus<\/em> sites in East Asia. Instead, Oldowan-type choppers and scrapers are found at those sites. If this technology seemed to be so important to African <em>Homo erectus<\/em>, why didn\u2019t East Asian <em>Homo erectus<\/em> also use the tools? One reason could be environmental differences between the two regions. It has been suggested that <em>Asian Homo<\/em><em>erectus<\/em> populations used perishable material such as bamboo to make tools. Another possibility is that <em>Homo erectus<\/em> (or even an earlier hominin) migrated to East Asia before the Acheulean technology developed in Africa. The recent discovery of the 2.1-million-year-old tools in China gives credence to this last explanation.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">What (if anything) do the Acheulean tools tell us about the mind of <em>Homo erectus<\/em>? Clearly, they took a fair amount of skill to manufacture. Apart from the actual shaping of the tool, other decisions made by toolmakers can reveal their use of foresight and planning. Did they just pick the most convenient rocks to make their tools, or did they search out a particular raw material that would be ideal for a particular tool? Analysis of Acheulean stone tools suggest that at some sites, the toolmakers selected their raw materials carefully\u2014traveling to particular rock outcrops to quarry stones and perhaps even removing large slabs of rock at the quarries to get at the most desirable material. Such complex activities would require advanced planning and communication with other individuals. However, other <em>Homo erectus<\/em> sites lack evidence of such selectivity; instead of traveling even a short distance for better raw material, the hominins tended to use what was available in their immediate area (Shipton et al. 2018).<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">In contrast to <em>Homo erectus<\/em> tools, the tools of early modern <em>Homo sapiens<\/em> during the Upper Paleolithic display tremendous diversity across regions and time periods. Additionally, Upper Paleolithic tools and artifacts communicate information such as status and group membership. Such innovation and social signaling seem to have been absent in <em>Homo erectus<\/em>, suggesting that they had a different relationship with their tools than did <em>Homo sapiens<\/em> (Coolidge and Wynn 2017). Some scientists assert that these contrasts in tool form and manufacture may signify key cognitive differences between the species, such as the ability to use a complex language.<\/span><\/p>\n<h3 class=\"import-Normal\"><span style=\"color: #000000\"><strong>Subsistence and Diet<\/strong><\/span><\/h3>\n<p class=\"import-Normal\"><span style=\"color: #000000\">In reconstructing the diet of <em>Homo erectus<\/em>, researchers can draw from multiple lines of evidence. These include stone tools used by <em>Homo erectus<\/em>, animal bones and occasionally plant remains from <em>Homo erectus<\/em> sites, and the bones and teeth of the fossils themselves. These data sources suggest that compared to the australopithecines, <em>Homo erectus<\/em> consumed more animal protein. Coinciding with the appearance of <em>Homo erectus<\/em> fossils in Africa are archaeological sites with much more abundant stone tools and larger concentrations of butchered animal bones.<\/span><\/p>\n<figure style=\"width: 253px\" class=\"wp-caption alignright\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image5-2.png\" alt=\"Five men excavating and note-taking at an archaeological site.\" width=\"253\" height=\"380\" \/><figcaption class=\"wp-caption-text\">Figure 11.14: Excavations at the site of Olorgesailie, Kenya. Dated from between 1.2 million years ago and 490,000 years ago, Olorgesailie has some of the most abundant and well-preserved evidence of Homo erectus activity in the world. Fossils of large mammals, such as elephants, along with thousands of Acheulean tools, have been uncovered over the decades. Credit: <a href=\"https:\/\/humanorigins.si.edu\/research\/olorgesailie-kenya\">Elephant Butchery Site Olorgesailie, Kenya<\/a> by<a href=\"https:\/\/www.si.edu\/\"> Smithsonian<\/a> [exhibit:<a href=\"https:\/\/humanorigins.si.edu\/research\"> Human Evolution Research<\/a>,<a href=\"https:\/\/humanorigins.si.edu\/research\/east-african-research-projects\"> East African Research Projects<\/a>, Olorgesailie, Kenya] is<a href=\"https:\/\/www.si.edu\/termsofuse\/\"> copyrighted and used for educational and non-commercial purposes as outlined by the Smithsonian<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">It makes sense that a larger body and brain would be correlated with a dietary shift to more calorically dense foods. This is because the brain is a very energetically greedy organ. Indeed, our own human brains require more than 20% of one\u2019s calorie total intake to maintain. When biologists consider the evolution of intelligence in any animal species, it is often framed as a cost\/benefit analysis: For large brains to evolve, there has to be a compelling benefit to having them and a way to generate enough energy to fuel them.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">One solution that would allow for an increase in human brain size would be a corresponding reduction in the size of the digestive tract (gut). According to the \u201cexpensive tissue hypothesis,\u201d initially formulated by Leslie Aiello and Peter Wheeler (1995), a smaller gut would allow for a larger brain without the need for a corresponding increase in the organism\u2019s metabolic rate. More meat in the diet could also fuel the larger brain and body size seen in the genus <em>Homo<\/em>. Some researchers also believe that body fat percentages increased in hominins (particularly females) around this time, which would have allowed them to be better buffered against environmental disruption such as food shortages (Anton and Snodgrass 2012).<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">As indicated above, evidence from archaeology and the inferences about <em>Homo erectus<\/em> body size suggest increased meat eating. How much hunting did <em>Homo erectus<\/em> engage in compared to the earlier Oldowan toolmakers? Although experts continue to debate the relative importance of hunting versus scavenging, there seems to be stronger evidence of hunting for these hominins. For example, at sites such as Olorgesailie in Kenya (Figure 11.14), there are numerous associations of Acheulean tools with butchered remains of large animals.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">However, <em>Homo erectus<\/em> certainly ate more than just meat. Studies of the tooth surfaces and microscopic wear patterns on hominin teeth indicate that these hominins ate a variety of foods, including some hard, brittle plant foods (Unger and Scott 2009). This would make sense, considering the environment was changing to be more dominated by grasslands in some areas. Roots, bulbs, and tubers (known as underground storage organs) of open savanna plants may have been a primary food source. Indeed, hunter-gatherer groups such as the Hadza of Tanzania rely heavily on such foods, especially during periods when game is scarce. In the unstable environment of the early Pleistocene, dietary versatility would be a definite advantage.<\/span><\/p>\n<h3 class=\"import-Normal\"><span style=\"color: #000000\"><strong>Tool Use, Cooking, and Fire<\/strong><\/span><\/h3>\n<p class=\"import-Normal\"><span style=\"color: #000000\">One key characteristic of the genus <em>Homo<\/em> is smaller teeth compared to <em>Australopithecus<\/em>. Why would teeth get smaller? In addition to new types of foods, changes in how food was prepared and consumed likely led to a decrease in tooth size. Think about how you would eat if you didn\u2019t have access to cutting tools. What you couldn\u2019t rip apart with your hands would have to be bitten off with your teeth\u2014actions that would require bigger, more powerful teeth and jaws. As stone tools became increasingly important, researchers propose that hominins began to cut up, tenderize, and process meat and plants, such that they did not have to use their teeth so vigorously.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Cooking food could also have contributed to the reduction in tooth and jaw size. In fact, anthropologist Richard Wrangham (2009) asserts that cooking played a crucial role in human evolution. Cooking provides a head start in the digestive process because of how heat begins to break down food before food even enters the body, and it can help the body extract more nutrients out of meat and plant foods such as starchy tubers.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Obviously cooking requires fire, and the earliest use of fire is a fascinating topic in the study of human evolution. Fire is not only produced by humans; it occurs naturally as a result of lightning strikes. Like other wild animals, early hominins must have been terrified of wildfires, but at some point in time they learned to control fire and put it to good use. Documenting the earliest evidence of fire has been a contentious issue in archaeology because of the difficulty in distinguishing between human-controlled fire and natural burning at hominin sites. Burned areas and ash deposits must have direct associations with human activity to make a case for deliberate fire use. Unfortunately, such evidence is rare at ancient hominin sites, which have been profoundly altered by humans, animals, and geological forces over millions of years. Recently, newer methods\u2014including microscopic analysis of burned rock and bone\u2014have revealed clear evidence of fire use at Koobi Fora, Kenya, dating to 1.5 million years ago (Hlubik et al. 2017).<\/span><\/p>\n<h3 class=\"import-Normal\"><span style=\"color: #000000\"><strong>Migration out of Africa<\/strong><\/span><\/h3>\n<p class=\"import-Normal\"><span style=\"color: #000000\"><em>Homo erectus<\/em> is generally thought to be the first hominin species to have left Africa. It is hypothesized that they settled in places in Eurasia, such as the Republic of Georgia, Indonesia, and northern China, where fossil evidence of <em>Homo erectus<\/em> exists. But why would this species have traveled such vast distances to these far-flung regions? To answer this question, we have to consider what we have learned about the biology, culture, and environmental circumstances of <em>Homo erectus. <\/em>It is proposed that the larger brain and body size of <em>Homo erectus<\/em> were fuelled by a diet consisting of more meat, and their longer, more powerful legs made it possible to walk and run longer distances to acquire food. It is suggested that since they were eating higher on the food chain, it was necessary for them to extend their home range to find sufficient game. Cultural developments\u2014including better stone tools and new technology such as fire\u2014 might have given them greater flexibility in adapting to different environments. Finally, the major Pleistocene climate shift discussed earlier in the chapter certainly played a role. Changes in air temperature, precipitation, access to water sources, and other habitat alteration had far-reaching effects on animal and plant communities; this included <em>Homo erectus<\/em>. If hominins were relying more on hunting, the migration patterns of their prey could have led them to traverse increasingly long distances.<\/span><\/p>\n<h3 class=\"import-Normal\"><span style=\"color: #000000\"><strong>Life History<\/strong><\/span><\/h3>\n<p class=\"import-Normal\"><span style=\"color: #000000\">The <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1558\">life history <\/a><\/strong> of a species refers to its overall pattern of growth, development, and reproduction during its lifetime, with the assumption that these characteristics have been shaped by natural selection. The field of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1559\">human behavioural ecology<\/a><\/strong>, explored in more detail in Appendix C, examines the roots of human behaviour and life history. Our species, <em>Homo sapiens<\/em>, is characterized by a unique life history pattern of slow development, an extended period of juvenile dependence, and a long lifespan. Whereas the offspring of great apes achieve self-sufficiency early, human children are dependent on their parents long after weaning. Additionally, human fathers and grandparents (particularly postmenopausal grandmothers) devote substantial time and energy to caring for their children.<\/span><\/p>\n<figure style=\"width: 310px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image15-3.png\" alt=\"One man is shooting a bow and arrow; another man is carrying a bow with a dog beside him.\" width=\"310\" height=\"465\" \/><figcaption class=\"wp-caption-text\">Figure 11.15: Hadza men practice bowing. Native to Tanzania, the Hadza have retained many traditional foraging practices. Although most do not subsist entirely upon wild foods today, their way of life may shed light on how humans lived for most of their evolutionary history. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Hadzabe1.jpg\">Hadzabe1<\/a> by<a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Idobi\"> Idobi<\/a> is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\"> CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Human behavioural ecologists who study modern hunter-gatherer societies have observed that foraging is no easy business (Figure 11.15). Members of these groups engage in complex foraging techniques that take many years to master. An extended juvenile period gives children the time to acquire these skills. It also allows time for large human brains to grow and mature. On the back end, a longer developmental period results in skilled, successful adults, capable of living a long time (Hill and Kaplan 1999). Despite the time and energy demands, females could have offspring at more closely spaced intervals if they could depend on help from fathers and grandmothers (Hawkes et al. 1998).<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">What can the study of <em>Homo erectus<\/em> reveal about its life history pattern? Well-preserved fossils such as the Nariokotome boy can provide some insights. We know that apes such as chimpanzees reach maturity more quickly than humans, and there is some evidence that the australopithecines had a growth rate more akin to that of chimpanzees. Scientists have conducted extensive studies of the Nariokotome skeleton\u2019s bones and teeth to assess growth and development. On the one hand, examination of the long bone ends (epiphyses) of the skeleton suggested that he was an early adolescent with a relatively large body mass, though growth had not yet been completed. On the other hand, study of the dentition, including measurement of microscopic layers of tooth enamel called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1573\">perikymata<\/a><\/strong>, revealed a much younger age of 8 or 9. According to Christopher Dean and Holly Smith (2009), the best explanation for this discrepancy between the dental and skeletal age is that <em>Homo erectus<\/em> had its own distinct growth pattern\u2014reaching maturity more slowly than chimpanzees but faster than <em>Homo sapiens<\/em>. This suggests that the human life history pattern of slow maturation and lengthy dependency was a more recent development. More work remains on refining this pattern for early <em>Homo<\/em>, but it is an important topic that sheds light on how and when we developed our unique life history characteristics.<\/span><\/p>\n<h2 class=\"import-Normal\"><span style=\"color: #000000\">The Big Picture of Early <em>Homo<\/em><\/span><\/h2>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">We are discovering that the evolution of the genus <em>Homo<\/em> is more complex than what was previously thought. The earlier view of a simple progression from <em>Australopithecus<\/em> to <em>Homo habilis<\/em> to <em>Homo erectus<\/em> as clearly delineated stages in human evolution just doesn\u2019t hold up anymore.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">As is apparent from the information presented here, there is tremendous variability during this time. While fossils classified as <em>Homo habilis<\/em> show many of the characteristics of the genus <em>Homo<\/em>, such as brain expansion and smaller tooth size, the small body size and long arms are more akin to australopithecines. There is also tremendous variability within the fossils assigned to <em>Homo habilis<\/em>, so there is little consensus on whether it is one or multiple species of <em>Homo<\/em>, a member of the genus <em>Australopithecus<\/em>, or even a yet-to-be-defined new genus. Similarly, there are considerable differences in skull morphology and body size and form of <em>Homo erectus<\/em>, of which some specimens show more similarity to <em>Homo habilis<\/em> than previously thought.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">What does this diversity mean for how we should view early <em>Homo<\/em>? First, there isn\u2019t an abrupt break between <em>Australopithecus<\/em> and <em>Homo habilis<\/em> or even between <em>Homo habilis<\/em> and <em>Homo erectus<\/em>. Characteristics we define as <em>Homo<\/em> don\u2019t appear as a unified package; they appear in the fossil record at different times. This is known as <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1560\">mosaic evolution<\/a><\/strong>. Indeed, fossil species such as <em>Australopithecus sediba<\/em>, as well as <em>Homo naledi<\/em> and <em>Homo floresiensis<\/em> (who will be introduced in Chapter 12), have displayed unexpected combinations of primitive and derived traits.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">We can consider several explanations for the diversity we see within early <em>Homo<\/em> from about 2.5 million to 1.5 million years ago. One possibility is the existence of multiple contemporaneous species of early <em>Homo <\/em>during this period. In light of the pattern of environmental instability discussed earlier, it shouldn\u2019t be surprising to see fossils from different parts of Africa and Eurasia display tremendous variability. Multiple hominin forms could also evolve in the same region, as they diversified in order to occupy different ecological niches. However, even the presence of multiple species of hominin does not preclude their interacting and interbreeding with one another. As you\u2019ll see in Appendix D, sequencing of ancient hominin genomes has led to deeper understanding of genetic relationships between extinct species such as the Neanderthals and Denisovans.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Diversity of brain and body sizes could also reflect developmental plasticity\u2014short-term adaptations within a lifetime (Anton et al. 2014). These have the advantage of being more flexible than genetic natural selection, which could only occur over many generations. For example, among human populations today, different body sizes are thought to be adaptations to different climate or nutritional environments. Under Pleistocene conditions of intense variability, a more flexible strategy of adaptation would be valuable.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">New discoveries are also questioning old assumptions about the behaviour of <em>Homo habilis<\/em> and <em>Homo erectus<\/em>. Just as the fossil evidence doesn\u2019t neatly separate <em>Australopithecus<\/em> and <em>Homo<\/em>, evidence of the lifeways of early <em>Homo <\/em>show similar diversity. For example, one of the traditional dividing lines between <em>Homo <\/em>and <em>Australopithecus<\/em> was thought to be stone tools: <em>Homo<\/em> made them; <em>Australopithecus <\/em>didn\u2019t. However, the recent discovery of stone tools from Kenya dating to 3.3 million years ago challenges this point of view. Similarly, the belief that <em>Homo erectus<\/em> was the first species to settle outside Africa may now come into question with the report of 2.1-million-year-old stone tools from China. If this find is supported by additional evidence, it may cause a reevaluation of <em>Homo erectus<\/em> being the first to leave Africa. Instead, there could have been multiple earlier migrations of hominins such as <em>Homo habilis<\/em> or even <em>Australopithecus <\/em>species.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">These various lines of evidence about the genus <em>Homo <\/em>point out the need for a more nuanced view of this period of human evolution. Rather than obvious demarcations between species and their corresponding behavioural advancements, it now looks like many behaviours were shared among species. Earlier hominins that we previously didn\u2019t think had the capability could have been doing things like expanding out of Africa or using stone tools. Meanwhile, some other hominins that we had considered more advanced didn\u2019t actually have the full suite of \u201chuman\u201d characteristics previously expected.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">From a student\u2019s perspective, all this complexity probably seems frustrating. It would be ideal if the human story were a straightforward, sequential narrative. Unfortunately, it seems that human evolution was not a nice, neat trajectory of increasingly humanlike traits and behaviours; rather, it is emblematic of the untidy but exciting nature of the study of human evolution.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Despite some haziness dominating the early <em>Homo<\/em> narrative, we can identify some overall trends for the million-year period associated with early <em>Homo. <\/em>These trends include brain expansion, a reduction in facial prognathism, smaller jaw and tooth size, larger body size, and evidence of full terrestrial bipedalism. These traits are associated with a key behavioural shift that emphasizes culture as a flexible strategy to adapt to unpredictable environmental circumstances. Included in this repertoire are the creation and use of stone tools to process meat obtained by scavenging and later hunting, a utilization of fire and cooking, and the roots of the human life history pattern of prolonged childhood, cooperation in child raising, and the practice of skilled foraging techniques. In fact, it\u2019s apparent that the cultural innovations are driving the biological changes, and vice versa, fueling a feedback loop that continues during the later stages of human evolution.<\/span><\/p>\n<h2>Cultural Connections and Contemporary Implications<\/h2>\n<\/div>\n<p>As we continue to uncover new archaeological evidence of our long-lost ancestry, the straightforward path we once imagined for human evolution becomes increasingly blurred, highlighting the complex and non-linear nature of evolutionary change. Even classifying species within the genus <em>Homo<\/em> can prove difficult. Characteristics such as brain size, common ancestry, and the adaptive use of the environment through tool use have become important components in determining whether a species belongs to the genus <em>Homo<\/em>, yet considerable debate remains. <em>Homo habilis<\/em>, often considered one of the earliest species of the genus <em>Homo<\/em>, continues to be debated in terms of its classification. Although evidence suggests that <em>Homo habilis<\/em> had a larger brain than <em>Australopithecus<\/em>, the discovery of additional fossils across East and South Africa has revealed considerable variation in morphological characteristics between sites. These variations have complicated our understanding of how different early hominins should be classified and their relationship to one another. What remains consistent, however, is the recurring archaeological evidence of stone tool use.<\/p>\n<p>Tool culture has been granted significant importance in the study of human evolution because it illustrates early hominins\u2019 ability to modify their environment according to their needs. Alongside developments such as bipedalism and increasing brain size, the emergence and diversification of stone tools provide important evidence of changing cognitive and behavioural capacities. Used for activities such as scavenging, hunting, and butchering, archaeological tools can reveal much about the lives of early members of the genus <em>Homo<\/em>. The Oldowan tool industry, for example, reflects a process that required selecting an appropriate stone and striking it at a particular angle to produce a desired edge. This suggests an ability not only to manipulate materials, but also to anticipate the outcome of an action and plan toward it. The Acheulean tool industry, often associated with <em>Homo erectus<\/em>, demonstrates an even greater degree of complexity. The diversification of tool forms and the development of bifacial tools suggest that tool production involved more than simply striking a stone at the correct angle, it required the maker to work toward a preconceived form or goal. These tools could be used to butcher meat, process animal hides, and perform other tasks that supported survival.<\/p>\n<p>The consistency and widespread distribution of Acheulean tools, which remained relatively stable for more than one million years, also provides important insight into the social and cultural lives of early members of the genus <em>Homo<\/em>. The similarities in tool forms across vast geographic areas suggest that knowledge of tool production was not simply rediscovered independently by individuals, but was learned and transmitted socially across generations. Producing an Acheulean tool required learning a particular technique, including how to select appropriate materials and reproduce a recognizable form. The continuation of these practices over such a long period therefore points to the existence of shared cultural knowledge and traditions. As early members of the genus <em>Homo<\/em> expanded into new environments, they may have carried not only physical tools with them, but also learned techniques, practices, and knowledge that connected them to other members of their communities. In this sense, stone tools can be understood not merely as evidence of technological or cognitive development, but as material expressions of social learning and cultural transmission. Their archaeological persistence offers a glimpse into how early hominins may have learned from one another, maintained shared practices, and passed knowledge between generations.<\/p>\n<h4>Discussion questions<\/h4>\n<ul>\n<li>What do the tools you use in your everyday life look like, and what do they reveal about your lifestyle and socio-cultural practices?<\/li>\n<li>Beyond stone tools, what other archaeological or fossil evidence could help us reconstruct the cultural practices, social relationships, and ways of life of early hominins?<\/li>\n<li>If archaeologists in the distant future studied our society through our material culture, how might they interpret our reliance on synthetic materials such as plastic and advanced technologies? What could these materials reveal about our social values, cultural practices, and relationship with our environment?<\/li>\n<\/ul>\n<div class=\"__UNKNOWN__\">\n<h2 class=\"import-Normal\"><span style=\"color: #000000\">Hominin Species Summaries<\/span><\/h2>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 344.15pt\">\n<tbody>\n<tr class=\"Table3-R\" style=\"height: 23pt\">\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Hominin<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><em>Homo habilis <\/em><\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 23pt\">\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Dates<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">2.5 million years ago to 1.7 million years ago<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 23pt\">\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Region(s)<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">East and South Africa<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 36pt\">\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Famous discoveries<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Olduvai Gorge, Tanzania; Koobi Fora, Kenya; Sterkfontein, South Africa<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 23pt\">\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Brain size<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">650 cc average (range from 510 cc to 775 cc)<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 23pt\">\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Dentition<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Smaller teeth with thinner enamel compared to <em>Australopithecus<\/em>; parabolic dental arcade shape<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 36pt\">\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Cranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Rounder cranium and less facial prognathism than <em>Australopithecus<\/em><\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 36pt\">\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Postcranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Small stature; similar body plan to <em>Australopithecus<\/em><\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 23pt\">\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Culture<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Oldowan tools<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 23pt\">\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Other<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">N\/A<\/span><\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 344.15pt\">\n<tbody>\n<tr class=\"Table4-R\" style=\"height: 23pt\">\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Hominin<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><em>Homo <\/em><em>erectus<\/em><\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 23pt\">\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Dates<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">1.8 million years ago to about 110,000 years ago<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 23pt\">\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Region(s)<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">East and South Africa; West Eurasia; China and Southeast Asia<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 36pt\">\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Famous discoveries<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Lake Turkana, Olorgesailie, Kenya; Java, Indonesia; Zhoukoudian, China; Dmanisi, Republic of Georgia<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 23pt\">\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Brain size<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Average 900 cc; range between 650 cc and 1,100 cc<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 23pt\">\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Dentition<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Smaller teeth than <em>Homo habilis<\/em><\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 36pt\">\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Cranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Long, low skull with robust features including thick cranial vault bones and large brow ridge, sagittal keel, and occipital torus<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 36pt\">\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Postcranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Larger body size compared to <em>Homo habilis<\/em>; body proportions (longer legs and shorter arms) similar to <em>Homo sapiens<\/em><\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 23pt\">\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Culture<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Acheulean tools (in Africa); evidence of increased hunting and meat-eating; use of fire; migration out of Africa<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 23pt\">\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Other<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">N\/A<\/span><\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div class=\"textbox shaded\">\n<h2 class=\"import-Normal\"><span style=\"color: #000000\">Review Questions<strong><br \/>\n<\/strong><\/span><\/h2>\n<ul>\n<li><span style=\"color: #000000\">Describe the climate during the early Pleistocene. Explain why climate is important for understanding the evolution of early <em>Homo<\/em>.<\/span><\/li>\n<li><span style=\"color: #000000\">List the key anatomical characteristics that are generally agreed to define the genus <em>Homo<\/em>.<\/span><\/li>\n<li><span style=\"color: #000000\">Why has classification of early<em> Homo <\/em>fossils proved difficult? What are some explanations for the variability seen in these fossils?<\/span><\/li>\n<li><span style=\"color: #000000\">Compare and contrast the Oldowan and Acheulean tool industries<em>.<\/em><\/span><\/li>\n<li><span style=\"color: #000000\">Name some specific behaviours associated with <em>Homo erectus<\/em> in the areas of tool use, subsistence practices, migration patterns, and other cultural innovations.<\/span><\/li>\n<\/ul>\n<\/div>\n<\/div>\n<h2 class=\"__UNKNOWN__\"><span style=\"color: #000000\">Key Terms<\/span><\/h2>\n<div class=\"__UNKNOWN__\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Acheulean<\/strong>: Tool industry characterized by teardrop-shaped stone handaxes flaked on both sides. <\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Developmental plasticity<\/strong>: The capability of an organism to modify its phenotype during development in response to environmental cues.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Human behavioural ecology<\/strong>: The study of human behaviour from an evolutionary and ecological perspective.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Life history<\/strong>: The broad pattern of a species\u2019 life cycle, including development, reproduction, and longevity.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Mosaic evolution<\/strong>: Different characteristics evolve at different rates and appear at different stages. <\/span><br style=\"clear: both\" \/><br style=\"clear: both\" \/><span style=\"color: #000000\"><strong>Occipital torus<\/strong>: A ridge on the occipital bone in the back of the skull.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Oldowan<\/strong>: Earliest stone-tool industry consisting of simple flakes and choppers.<\/span><br style=\"clear: both\" \/><span style=\"color: #000000\"><strong><br style=\"clear: both\" \/>Perikymata<\/strong>: Microscopic ridges on the surface of tooth enamel that serve as markers of tooth development.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Pleistocene<\/strong>: Geological epoch dating from 2.6 million years ago to about 11,000 years ago.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Pliocene:<\/strong> Geological epoch dating from 5.3 to 2.6 million years ago.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Prognathism<\/strong>: Condition where the lower face and jaw protrude forward from a vertical plane.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Sagittal keel<\/strong>: A thickened area along the top of the skull.<\/span><\/p>\n<\/div>\n<p><span style=\"color: #000000;font-family: Raleway, sans-serif;font-size: 1.5em\">FOR FURTHER EXPLORATION<\/span><\/p>\n<div class=\"__UNKNOWN__\">\n<p class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\">Boaz, Noel Thomas, and Russell L. Ciochon. 2004. <em>Dragon Bone Hill: An Ice-Age Saga of <\/em>Homo erectus. New York: Oxford University Press.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\"><a href=\"https:\/\/humanorigins.si.edu\/\">Human Evolution by the Smithsonian Institution<\/a>. Produced by the Smithsonian National Museum of Natural History, this website covers many aspects of human evolution including 3-D models of hominin fossils.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\">Lewin, Roger, and Robert A. Foley. 2004. <em>Principles of Human Evolution<\/em>. Oxford, UK: Blackwell Publishing.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Mutu, Kari. \u201cHonour Finds Kenya\u2019s Oldest Fossil Hunter Kamoya Kimeu.\u201d <em>The East African<\/em>, July 19, 2021.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Nordling, Linda. \u201cRaising Up African Paleoanthropologists.\u201d <em>SAPIENS, <\/em>September 28, 2021. Accessed February 24, 2023. <a class=\"rId110\" style=\"color: #000000\" href=\"https:\/\/www.sapiens.org\/biology\/african-paleoanthropologists\/\"><em>https:\/\/www.sapiens.org\/biology\/african-paleoanthropologists\/<\/em><\/a>.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Risen, Clay. \u201cKamoya Kimeu, Fossil-Hunting \u2018Legend\u2019 in East Africa Is Dead.\u201d<em> New York Times<\/em>, August 11, 2022. Accessed February 24, 2023. https:\/\/www.nytimes.com\/2022\/08\/11\/science\/kamoya-kimeu-dead.html\/.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Stoneking, Mark. 2015. \u201cOf Lice and Men: The Molecular Evolution of Human Lice.\u201d Lecture, Center for Academic Research &amp; Training in Anthropogeny, San Diego, California, October 16, 2015. Accessed February 24, 2023. <a class=\"rId111\" style=\"color: #000000\" href=\"https:\/\/carta.anthropogeny.org\/events\/unique-features-human-skin\">https:\/\/carta.anthropogeny.org\/events\/unique-features-human-skin<\/a>.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\">Tarlach, Gemma. 2015. \u201cThe First Humans to Know Winter.\u201d <em>Discover<\/em>, February 26. https:\/\/www.discovermagazine.com\/planet-earth\/the-first-humans-to-know-winter<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Ungar, Peter S. 2017. <em>Evolution's Bite: A Story of Teeth, Diet, and Human Origins<\/em>. 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Aiello. 2014. \u201cEvolution of Early <em>Homo<\/em>: An Integrated Biological Perspective.\u201d <em>Science<\/em> 345 (6192) doi: 10.1126\/science.1236828.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\">Anton, Susan C., and J. Josh Snodgrass. 2012. \u201cOrigins and Evolution of Genus <em>Homo<\/em>: New Perspectives.\u201d <em>Current Anthropology<\/em> 53 (S6): S479\u2013S496.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\">Ashton, Nick, Simon G. Lewis, Isabelle De Groote, Sarah M. 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Dordrecht: Springer Netherlands.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\">deMenocal, Peter B. 2014. \u201cClimate Shocks.\u201d <em>Scientific American<\/em> 311 (3): 48\u201353.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\">Dennell, Robin, and Wil Roebroeks. 2005. \u201cAn Asian Perspective on Early Human Dispersal from Africa.\u201d <em>Nature<\/em> 438 (7071): 1099\u20131104.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\">Hawkes, Kristen, James F. O\u2019Connell, Nicholas G. Blurton Jones, Helen Alvarez, and Eric L. Charnov. 1998. \u201cGrandmothering, Menopause, and the Evolution of Human Life\u2009Histories.\u201d <em>Proceedings of the National Academy of Sciences<\/em> 95 (3): 1336\u20131339.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\">Herries, A. I. R., J. M. Martin, A. B. Leece, J. W. Adams, G. Boschian, R. Joannes-Boyau, T. R. Edwards, et al. 2020. \"Contemporaneity of <em>Australopithecus<\/em>, <em>Paranthropus<\/em>, and early <em>Homo erectus<\/em> in South Africa.\" <em>Science<\/em> 368 (6486). https:\/\/doi.org\/10.1126\/science.aaw7293<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\">Hill, Kim, and Hillard Kaplan. 1999. \u201cLife History Traits in Humans: Theory and Empirical Studies.\u201d <em>Annual Review of Anthropology<\/em> 28: 397\u2013430.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\">Hlubik, Sarah, Francesco Berna, Craig Feibel, David Braun, and John W. K. 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Jennings, et al. 2018. \u201cAcheulean Technology and Landscape Use at Dawadmi, Central Arabia.\u201d <em>PloS one<\/em> 13 (7): e0200497\u2013e0200497.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\">Simpson, Scott W., Jay Quade, Naomi E. Levin, Robert Butler, Guillaume Dupont-Nivet, Melanie Everett, and Sileshi Semaw. 2008. \u201cA Female <em>Homo<\/em><em>erectus<\/em> Pelvis from Gona, Ethiopia.\u201d <em>Science<\/em> 322 (5904): 1089\u20131092.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\">Ungar, Peter S., and Robert S. Scott. 2009. \u201cDental Evidence for Diets of Early <em>Homo<\/em>.\u201d In <em>The First Humans: Origin and Early Evolution of the Genus Homo<\/em>, edited by Frederick E. Grine, John G. Fleagle, and Richard E. Leakey, 121\u2013134. 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New York: Basic Books.<\/span><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;margin-right: -36pt;text-indent: 0pt\"><span style=\"color: #000000\">Zhu, Zhaoyu, Robin Dennell, Weiwen Huang, Yi Wu, Shifan Qiu, Shixia Yang, and Zhiguo Rao. 2018. \u201cHominin Occupation of the Chinese Loess Plateau Since about 2.1 Million Years Ago.\u201d <em>Nature<\/em> 559: 608\u2013612.<\/span><\/p>\n<h2 class=\"import-Normal\"><span style=\"color: #000000\">Acknowledgements<br \/>\n<\/span><\/h2>\n<p class=\"import-Normal\"><span style=\"color: #000000\">The author gratefully acknowledges funding from the California Community Colleges Chancellor\u2019s Office Zero Textbook Cost Degree Grant Program\u2014Implementation Phase 2.<\/span><\/p>\n<\/div>\n<\/div>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1695_1877\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1695_1877\"><div tabindex=\"-1\"><div class=\"__UNKNOWN__\">\n<div class=\"textbox\">\n<h6>Student contributors to this chapter: Peyton Dagg, Bryana Henry, Anoriel Jacques, Saehee Yoon, and Brandon Hawke<\/h6>\n<p>Learn more about <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/about-the-authors\/\">authors and editors<\/a>,<a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/student-contributors\/\"> Hess' student contributions<\/a>, and <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/versioning-history\/\">versioning history<\/a>.<\/p>\n<div class=\"textbox textbox--learning-objectives\">\n<header class=\"textbox__header\">\n<h2 class=\"textbox__title\">Learning Objectives<\/h2>\n<\/header>\n<div class=\"textbox__content\">\n<ul>\n<li class=\"import-Normal\">Identify the main groupings of Archaic <em>Homo sapiens<\/em>, such as Neanderthals.<\/li>\n<li class=\"import-Normal\">Explain how shifting environmental conditions required flexibility of adaptations, both anatomically and behaviourally.<\/li>\n<li class=\"import-Normal\">Describe the unique anatomical and cultural characteristics of Archaic <em>Homo sapiens, <\/em>including Neanderthals, in contrast to other hominins.<\/li>\n<li class=\"import-Normal\">Articulate how Middle Pleistocene hominin fossils fit into evolutionary trends including cranial capacity (brain size) development, cultural innovations, and migration patterns.<\/li>\n<li class=\"import-Normal\">Identify the shared traits, regional variations, and local adaptations among Archaic <em>Homo sapiens.<\/em><\/li>\n<li class=\"import-Normal\">Detail the increased complexity and debates surrounding the classification of hominins in light of transitional species, species admixture, etc.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<h2 class=\"import-Normal\">Breaking the Stigma of the \"Caveman\"<\/h2>\n<p class=\"import-Normal\">What do you think of when you hear the word \u201ccaveman\u201d? Perhaps you imagine a character from a film such as <em>The Croods<\/em>, <em>Tarzan<\/em>, and <em>Encino Man<\/em> or from the cartoon <em>The Flintstones<\/em>. Maybe you picture the tennis-playing, therapy-going hairy Neanderthals from Geico Insurance commercials. Or perhaps you imagine characters from <em>The Far Side<\/em> or <em>B.C.<\/em> comics. Whichever you picture, the character in your mind is likely stooped over with a heavy brow, tangled long locks and other body hair, and clothed in animal skins, if anything. They might be holding a club with a confused look on their face, standing at the entrance to a cave or dragging an animal carcass to a fire for their next meal (see Figure 12.1). You might have even signed up to take this course because of what you knew\u2014or expected to learn\u2014about \u201ccavemen.\u201d<\/p>\n<figure style=\"width: 163px\" class=\"wp-caption alignleft\"><img src=\"https:\/\/cdn.pixabay.com\/photo\/2013\/07\/13\/12\/36\/caveman-159964_1280.png\" alt=\"Free caveman beard man vector\" width=\"163\" height=\"317\" \/><figcaption class=\"wp-caption-text\">Figure 12.1: Cartoon illustration of a prehistoric \u201ccaveman\u201d, commonly used as a visual representation of early humans in the Stone Age. Credit: <em data-start=\"261\" data-end=\"293\">Caveman, Beard, Man, Primitive<\/em> free to use under the Pixabay <a href=\"https:\/\/pixabay.com\/service\/license-summary\/\" target=\"_blank\">Content License.<\/a><\/figcaption><\/figure>\n<p class=\"import-Normal\">These images have long been the stigma and expectation about our ancestors at the transition to modern <em>Homo sapiens<\/em>. Tracing back to works as early as Carl Linnaeus, scientists once propagated and advanced this imagery, creating a clear picture in the minds of early scholars that informed the general public, even through today, that Archaic <em>Homo sapiens<\/em>, \u201ccavemen,\u201d were somehow fundamentally different and much less intelligent than we are now. Unfortunately, this view is overly simplistic, misleading, and incorrect. Understanding what Archaic <em>Homo sapiens<\/em> were actually like requires a much more complex and nuanced picture, one that comes into sharper focus as continuing research uncovers more about the lives of our not-too-distant (and not-too-different) ancestors.<\/p>\n<p class=\"import-Normal\">The first characterizations of Archaic <em>Homo sapiens<\/em> were formed from limited fossil evidence in a time when <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1582\">ethnocentric<\/a><\/strong> and species-centric perspectives (<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1583\">anthropocentrism<\/a><\/strong>) were more widely accepted and entrenched in both society and science. Today, scientists are working from a more complete fossil record from three continents (Africa, Asia, and Europe), and genetic evidence informs their analyses and conclusions. The existence of Archaic <em>Homo sapiens<\/em> marks an exciting point in our lineage\u2014a point at which many modern traits had emerged and key refinements were on the horizon. Anatomically, humans today are not that much different from Archaic <em>Homo sapiens<\/em>.<\/p>\n<h2><\/h2>\n<h2 class=\"import-Normal\">The Changing Environment<\/h2>\n<p class=\"import-Normal\">While modern climate change is of critical concern today due to its cause (human activity) and pace (unprecedentedly rapid), the existence of global climate change itself is not a recent phenomenon. The focus of this chapter, the Middle Pleistocene (roughly between 780 kya and 125 kya), is the time period in which Archaic <em>Homo sapiens <\/em>appears in the fossil record\u2014a time that witnessed some of the most drastic climatic changes in human existence. During this time period, there were 15 major and 50 minor glacial events in Europe, alone.<\/p>\n<p class=\"import-Normal\">What exactly is <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1635\">glaciation<\/a><\/strong>? When scientists talk about glacial events, they are referring to the climate being in an ice age. This means that the ocean levels were much lower than today, because much of the earth\u2019s water was tied up in large glaciers or ice sheets. Additionally, the average temperature would have been much cooler, which would have better supported an Arctic or tundra-adapted plant-and-animal ecosystem in northern latitudes. The most interesting and relevant features of Middle Pleistocene glacial events are the sheer number of them and their repeated bouts: this era alternated between glacial periods and warmer periods, known as<strong> interglacials<\/strong>. In other words, the planet wasn\u2019t in an ice age the whole time.<\/p>\n<p class=\"import-Normal\">You can see the dramatic and increasing fluctuations in temperature, recorded through <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_906\">foraminifera<\/a><\/strong>, in Figure 12.2. The distance between highs and lows demonstrates the severity of temperature shifts. Much as the Richter scale represents more intense earthquakes with more dramatic peaks, so too does this chart, which uses dramatic peaks to demonstrate intense temperature swings.<\/p>\n<figure id=\"attachment_346-3\" aria-describedby=\"caption-attachment-346-3\" style=\"width: 1753px\" class=\"wp-caption alignnone\"><img class=\"size-full wp-image-329\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/All_palaeotemps.png\" alt=\"The graph shows changes in Earth\u2019s temperature for the last 540 My.\" width=\"1753\" height=\"565\" \/><figcaption id=\"caption-attachment-346-3\" class=\"wp-caption-text\">Figure 12.2: The Geologic Timescale and corresponding temperature shifts. Wide and rapid shifts took place during the Pleistocene (the second box from the right). More dramatic fluctuations depict greater severity of temperature shift. The Eocene, Pliocene, and Holocene epochs had more stable temperatures. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:All_palaeotemps.png\" target=\"_blank\">All paleotemps<\/a> by Glen Fergus is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Glacial periods are defined by Earth\u2019s average temperature being lower. Worldwide, temperatures are reduced, with cold areas becoming even colder. Huge portions of the landscape may have become inaccessible during glacial events due to the formation of glaciers and massive ice sheets. In Europe, the Scandinavian continental glacier covered what is today Ireland, England, Sweden, Norway, Denmark, and some of continental Europe. Plant and animal communities shifted to lower latitudes along the periphery of ice sheets. Additionally, some new land was opened during glacials. Evaporation with little runoff reduced sea levels by as much as almost 150 metres, shifting coastlines outward by in some instances as much as almost 100 kilometres. Additionally, land became exposed that connected what were previously unconnected continents such as Africa into Yemen at the Gulf of Aden.<\/p>\n<p class=\"import-Normal\">Glacial periods also affected equatorial regions and other regions that are today thought of as warmer or at least more temperate parts of the globe, including Africa. While these areas were not covered with glaciers, increased global glaciation resulted in lower sea levels and expanded coastlines. Cooler temperatures were accompanied by the drying of the climate, which caused significantly reduced rainfall, increased aridity, and the expansion of deserts. It is an interesting question to consider whether the same plants and animals that lived in these regions prior to the ice ages would be able to survive and thrive in this new climate. Plant and animal communities shifted in response to the changing climate, whenever possible.<\/p>\n<h2 class=\"import-Normal\">Surviving During the Middle Pleistocene<\/h2>\n<p class=\"import-Normal\">Rather than a single selective force, the Middle Pleistocene was marked by periods of fluctuation, not just cold periods. Interglacials interrupted glaciations, reversing trends in sea level, coastline, temperature, precipitation, and aridity, as well as glacier size and location. Interglacials are marked by increased rainfall and a higher temperature, which causes built-up ice in glaciers to melt. This leads to glacial retreat, which is the shrinking of glaciers and the movement of the glaciers back toward the poles, as we\u2019ve seen in our lifetime. During interglacials, sea levels increase, flooding some previously exposed coastlines and continental connections. In addition, plant and animal communities shift accordingly, often finding more temperate climates to the north and less arid and more humid climates in the tropics (Van Andel and Tzedakis 1996).<\/p>\n<p class=\"import-Normal\">Scientists have found that the Olorgesailie region in southern Kenya was at various times in the Middle Pleistocene a deep lake, a drought-dried lakebed with an area criss-crossed by small streams, and a grassland. While various animal species would have moved in and out of the area as the climate shifted, some animal species went extinct, and new, often related, species took up residence. The trend, scientists noted, was that animals with more specialized features went extinct and animals with more generalized features, such as animals we see today, survived in this changing climatic time period. For example, a zebra with specialized teeth for eating grass was ultimately replaced by a zebra that could eat both grass and other types of vegetation. If this small, localized example shows such a dramatic change in terms of the environment and the plant and animal biocommunities, what would have been the impact on humans?<\/p>\n<p class=\"import-Normal\">There is no way humans could have escaped the effects of Middle Pleistocene climate change, no matter what region of the world they were living in. As noted earlier, and as evidenced by what was seen in the other biotic communities, humans would have faced changing food sources as previous sources of food may have gone extinct or moved to a different latitude. Depending on where they were living, fresh water may have been limited. Durial glacials, lower sea levels would have given humans more land to live on, while the interglacials would have reduced the available land through the increase in rainfall and associated sea level rise. Dry land connections between the continents would have made movement from one continent to another by foot easier at times than today, although these passageways were not consistently available through the Middle Pleistocene due to the glacial\/interglacial cycle. Finally, as evidenced by the Olorgesailie region in Kenya, during the Middle Pleistocene animal species that were overly specialized to one particular type of environment were less likely to survive when compared to their more generalized counterparts. Evidence suggests that this same pattern may have held true for Archaic <em>Homo sapiens<\/em>, in terms of their ability to survive this dramatic period of climate change.<\/p>\n<h2 class=\"import-Normal\">Defining Characteristics of Archaic <em>Homo sapiens<\/em><\/h2>\n<p class=\"import-Normal\">Archaic <em>Homo sapiens<\/em> share our species name but are distinguished by the term \u201cArchaic\u201d as a way of recognizing both the long period of time between their appearance and ours, as well as the way in which human traits have continued to evolve over time\u2014making Archaic <em>Homo sapiens <\/em>look slightly different from us today, despite being considered the same species. Living throughout Africa, and the Middle East during the Middle Pleistocene, Archaic <em>Homo sapiens <\/em>are considered, in many ways, transitional between <em>Homo <\/em><em>erectus<\/em> and modern <em>Homo sapiens <\/em>(see Figure 12.3). Archaic<em> Homo sapiens<\/em> share the defining trait of an increased brain size of at least 1,100 cc and averaging 1,200 cc, although there are significant regional and temporal (time) variations. Because of these variations, scientists disagree on whether these fossils represent a single, variable species or multiple, closely related species (sometimes called <em>Homo antecessor<\/em>,<em> Homo bodoensis, Homo heidelbergensis<\/em>,<em> Homo georgicus<\/em>,<em> Homo neanderthalensis<\/em>, and <em>Homo rhodesiensis<\/em>).<\/p>\n<p class=\"import-Normal\">An active area of scholarship in the discipline involves reconciling the diversity of species from this time period and establishing the phylogenetic relationships between them. The term \u201cArchaic <em>Homo sapiens\u201d <\/em>can mean different things to different scholars within the discipline. The intent of this chapter is to provide an understanding of the diversity of this time period and provide data used to make interpretations from among the most likely possibilities. Although we recognize that some anthropologists split many of these fossils into separate species, until the issue is resolved at the discipline level, this chapter will rely on the widely used naming conventions that refer to many fossils from this time period as Archaic <em>Homo sapiens<\/em>. We will discuss these contemporaneous fossils as a unit<em>, <\/em>with the exception of a particularly unique population living in Europe and West Asia known as the Neanderthals, which we will examine separately.<\/p>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<caption>Figure 12.3: A comparison of Homo erectus, Archaic Homo sapiens, and anatomically modern Homo sapiens. This table compares key traits of the crania and postcrania that distinguish these three hominins. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-16\/\" target=\"_blank\">Homo erectus, Archaic Homo sapiens, and anatomically modern Homo sapiens table (Figure 11.3)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Amanda Wolcott Paskey and AnnMarie Beasley Cisneros is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/caption>\n<thead>\n<tr style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Trait<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong><em>Homo <\/em><\/strong><strong><em>erectus<\/em><\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Archaic <\/strong><strong><em>Homo sapiens <\/em><\/strong><strong>(including Neaderthals)<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Anatomically Modern <\/strong><strong><em>Homo sapiens<\/em><\/strong><\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Time<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1.8 mya\u2013200,000 ya<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">600,000\u201340,000 ya<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">315,000 ya\u2013today<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Brain size<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">900 cc<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1,200 cc (1,500 cc when including Neanderthals)<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1,400 cc<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Skull Shape<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Long and low,<\/p>\n<p class=\"import-Normal\">angular<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Intermediate<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Short and high, <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1643\">globular<\/a><\/strong><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Forehead<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Absent<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Emerging<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Present<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Nasal Region<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Projecting nasal bones (bridge of the nose), no midfacial prognathism<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Wider nasal aperture and some midfacial prognathism, particularly pronounced among Neanderthals<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Narrower nasal aperture, no midfacial prognathism<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Chin<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Absent<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Absent<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Present<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Other Facial Features<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Large brow ridge and large projecting face<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Intermediate<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Small brow ridge and<strong> retracted face<\/strong><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Other Skull Features<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Nuchal torus, sagittal keel, thick cranial bone<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Projecting occipital bone, often called occipital bun in Neanderthals; intermediate thickness of cranial bone<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Small bump on rear of skull, if anything; thin cranial bone<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dentition<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Large teeth, especially front teeth<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Slightly smaller teeth; front teeth still large;<\/p>\n<p class=\"import-Normal\">retromolar gap in Neanderthals<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Smaller teeth<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Postcranial Features<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Robust bones of skeleton<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Robust bones of skeleton<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">More gracile bones of skeleton<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<p class=\"import-Normal\">When comparing <em>Homo <\/em><em>erectus<\/em>, Archaic<em> Homo sapiens, <\/em>and anatomically modern <em>Homo sapiens<\/em>, one can see that Archaic<em> Homo sapiens<\/em> are intermediate in their physical form. For some features, this follows the trends first seen in <em>Homo <\/em><em>erectus<\/em> with other features having early, less developed forms of traits seen in modern <em>Homo sapiens<\/em>. For example, Archaic <em>Homo sapiens<\/em> trended toward less angular and higher skulls than <em>Homo <\/em><em>erectus<\/em><em>. <\/em>However, the archaic skulls were not as short and globular and had less developed foreheads compared to anatomically modern <em>Homo sapiens. <\/em>Archaic <em>Homo sapiens<\/em> had smaller brow ridges and a less-projecting face than <em>Homo <\/em><em>erectus<\/em> and slightly smaller teeth, although incisors and canines were often about as large as those of <em>Homo <\/em><em>erectus<\/em>. Archaic <em>Homo sapiens <\/em>also had a wider <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1638\">nasal aperture<\/a><\/strong>, or opening for the nose, and a forward-projecting midfacial region, which is later seen more fully developed among Neanderthals and is known as <strong>midfacial prognathism<\/strong>. The occipital bone often projected and the cranial bone was of intermediate thickness, somewhat reduced from <em>Homo <\/em><em>erectus<\/em> but not nearly as thin as that of anatomically modern <em>Homo sapiens. <\/em>The postcrania remained fairly robust. Identifying a set of features that is unique to Archaic<em> Homo sapiens<\/em> is a challenging task, due to both individual and geographic variation\u2014these developments were not all present to the same degree in all individuals. Neanderthals are the exception, as they had several unique traits that made them notably different from modern <em>Homo sapiens<\/em> as well as their closely related Archaic cousins.<\/p>\n<figure style=\"width: 299px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image10-4.png\" alt=\"Archaic Homo sapiens skull cast.\" width=\"299\" height=\"299\" \/><figcaption class=\"wp-caption-text\">Figure 12.4: \u201cBroken Hill Man,\u201d found at Kabwe in Zambia, shows common traits associated with archaic Homo sapiens in Africa, including a large brain, taller cranium, and Homo erectus-like features such as massive brow ridges, a large face, and thick cranial bones. Credit: <a href=\"https:\/\/boneclones.com\/product\/homo-heidelbergensis-skull-broken-hill-1-rhodesian-man-BH-004\" target=\"_blank\">Homo heidelbergensis Cranium Broken Hill 1 (Rhodesian Man)<\/a> by <a href=\"https:\/\/boneclones.com\/\" target=\"_blank\">\u00a9BoneClones<\/a> is used by permission and available here under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">The one thing that is clear about Archaic <em>Homo sapiens<\/em> is that, despite general features, there is a lot of regional variation, which is first seen in the different <em>Homo <\/em><em>erectus<\/em> specimens across Asia and Africa. While the general features of Archaic <em>Homo sapiens<\/em>, identified earlier, are present in the fossils of this time period, there are significant regional differences. The majority of this regional variation lies in the degree to which fossils have features more closely aligned with <em>Homo <\/em><em>erectus<\/em> or with anatomically modern <em>Homo sapiens<\/em>.<\/p>\n<figure style=\"width: 244px\" class=\"wp-caption alignright\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image7-5.png\" alt=\"Side view of the Dali cranium.\" width=\"244\" height=\"213\" \/><figcaption class=\"wp-caption-text\">Figure 12.5: Dali cranium, found at Dali, China, is representative of traits seen in archaic Homo sapiens in Asia, including large and robust features with heavy brow ridges like Homo erectus and a large cranial capacity intermediate between Homo erectus and anatomically modern Homo sapiens. Credit: Dali skull original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by <a href=\"https:\/\/marynelsonstudio.com\" target=\"_blank\">Mary Nelson<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p>To illustrate this point, we will examine three exemplary specimens, one from each of the three continents on which Archaic<em> Homo sapiens <\/em>lived. First, in Africa, a specimen from Broken Hill is one of several individuals found in the Kabwe lead mine in Zambia. It had a large brain (1,300 cc) and taller cranium as well as many <em>Homo erectus-<\/em>like skull features, including massive brow ridges, a large face, and thick cranial bones (Figure 12.4). Second, one partial crania from Dali, China, is representative of Archaic<em> Homo sapiens <\/em>in Asia, with large and robust features with heavy brow ridges, akin to what is seen in <em>Homo <\/em><em>erectus<\/em>, and a large cranial capacity intermediate between <em>Homo <\/em><em>erectus<\/em> and anatomically modern <em>Homo sapiens<\/em> (Figure 12.5). Third, an almost-complete skeleton was found in northern Spain at Atapuerca. Atapuerca 5 (Figure 12.6) has thick cranial bone, an enlarged cranial capacity, intermediate cranial height, and a more rounded cranium than seen previously. Additionally, Atapuerca 5 demonstrates features that foreshadow Neanderthals, including increased midfacial prognathism. After examining some of the fossils such as those from Kabwe, Dali, and Atapuerca, the transitional nature of Archaic<em> Homo sapiens <\/em>is clear: their features place them squarely between <em>Homo <\/em><em>erectus<\/em> and modern <em>Homo sapiens<\/em>.<\/p>\n<figure style=\"width: 293px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image13-4.png\" alt=\"Archaic Homo sapiens skull cast with mandible.\" width=\"293\" height=\"293\" \/><figcaption class=\"wp-caption-text\">Figure 12.6: Atapuerca 5 archaic Homo sapiens, found in northern Spain, is representative of traits seen in archaic Homo sapiens in Europe, including a thick cranial bone, an enlarged cranial capacity, intermediate cranial height, a more rounded cranium, and increased midfacial projection. Credit: <a href=\"https:\/\/boneclones.com\/product\/homo-heidelbergensis-skull-atapuerca-5-BH-022\" target=\"_blank\">Homo heidelbergensis Skull Atapuerca 5<\/a> by <a href=\"https:\/\/boneclones.com\/\" target=\"_blank\">\u00a9BoneClones<\/a> is used by permission and available here under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Due to the transitional nature of Archaic<em> Homo sapiens<\/em>, identifying the time period with which they are associated is problematic and complex. Generally, it is agreed that Archaic<em> Homo sapiens <\/em>lived between 600,000 and 200,000 years ago, with regional variation and overlap between <em>Homo <\/em><em>erectus<\/em> on the early end of the spectrum and modern <em>Homo sapiens <\/em>and Neanderthals on the latter end. The earliest-known Archaic<em> Homo sapiens <\/em>fossils tentatively date to about 600,000 years ago in Africa, to around 300,000 years ago in Asia, and to about 350,000 years ago in Europe (and potentially as early as 600,000 years ago). Determining the end point of Archaic<em> Homo sapiens <\/em>is also problematic since it largely depends upon when the next subspecies of <em>Homo sapiens <\/em>appears and the classification of highly intermediate specimens. For example, in Africa, the end of Archaic<em> Homo sapiens <\/em>is met with the appearance of modern <em>Homo sapiens<\/em>, while in Europe it is the appearance of Neanderthals that is traditionally seen as marking the transition from other Archaic<em> Homo sapiens. <\/em><\/p>\n<p class=\"import-Normal\">It is important to remember that this time period is represented by many branching relationships and assuming an evolutionary trajectory that follows a single linear path would not be correct. Even still, Archaic<em> Homo sapiens <\/em>mark an important chapter in the human lineage, connecting more ancestral forms, such as <em>Homo <\/em><em>erectus<\/em>, to modern <em>Homo sapiens<\/em>. During this period of climatic transition and fluctuation, Archaic <em>Homo sapiens<\/em> mirror the challenges of their environments. Showing increasing regional variation due to the need for local adaptation, there is no single archetype for this group; the defining characteristic seems to be variability.<\/p>\n<h2 class=\"import-Normal\">Neanderthals<\/h2>\n<p class=\"import-Normal\">One well-known population of Archaic <em>Homo sapiens <\/em>are the Neanderthals, named after the site where they were first discovered in the Neander Valley, or \u201cthal\u201d in German, located near Dusseldorf, Germany. Popularly known as the stereotypical \u201ccavemen\u201d examined at the outset of this chapter, recent research is upending long-held beliefs about this group of Archaics. Neanderthal behaviour was increasingly complex, far beyond what was exhibited by even other Archaic <em>Homo sapiens<\/em> discussed throughout this chapter. We implore you to forget the image of the iconic caveman and have an open mind when exploring the fossil evidence of the Neanderthals.<\/p>\n<p class=\"import-Normal\">It is important to understand why Neanderthals are separated from other Archaic <em>Homo sapiens<\/em>. Unlike the rest of Archaic <em>Homo sapiens<\/em>, Neanderthals are easily defined and identified in many ways. Evidence suggests the time period when Neanderthals lived was between 150,000 and 40,000 years ago. There is a clear geographic boundary of where Neanderthals lived: western Europe, the Middle East, and western Asia. No Neanderthal fossils have ever been discovered outside of this area, including Africa. This is a bit curious, as other Archaics seem to have adapted in Africa and then migrated elsewhere, but Neanderthals\u2019 regional association makes sense in light of the environment to which they were best adapted: namely, extreme cold weather. Additionally, Neanderthals have a unique and distinct cluster of physical characteristics. While a few aspects of Neanderthals are shared among some Archaic <em>Homo sapiens<\/em>, such as the types of tools, most Neanderthal anatomical and behavioural attributes are unique to them.<\/p>\n<p class=\"import-Normal\">Neanderthals lived during some of the coldest times during the last Ice Age and at far northern latitudes. This means Neanderthals were living very close to the glacial edge, rather than in a more temperate region of the globe like some of their Archaic <em>Homo sapiens<\/em> relatives. While able to survive in arctic conditions, most Neanderthal sites dating to the glacial periods were found farther away from the severe cold, in a steppe tundra-like environment, which would have been more hospitable to Neanderthals, and their food sources, both flora and fauna (Ashton 2002; Nicholson 2017; Richter 2006). Their range likely expanded and contracted along with European glacial events, moving into the Middle East during glacial events when Europe became even cooler, and when the animals they hunted would have moved for the same reason. During interglacials, when Europe warmed a bit, Neanderthals and their prey would have been able to move back into Western Europe. Clearly, the true hallmark of Neanderthals is their adaptation to an unstable environment, shifting between warm and cold, as the climate was in constant flux throughout their existence (Adler Et al. 2003; Boettger Et al. 2009).<\/p>\n<p class=\"import-Normal\">Many of the Neanderthals\u2019 defining physical features are more extreme and robust versions of traits seen in other Archaic<em> Homo sapiens<\/em>, clustered in this single population. Brain size, namely an enlargement of the cranial capacity, is one such trait. The average Neanderthal brain size is around 1,500 cc, and the range for Neanderthal brains can extend to upwards of 1,700 cc. The majority of the increase in the brain occurs in the occipital region, or the back part of the brain, resulting in a skull that has a large cranial capacity with a distinctly long and low shape that is slightly wider than previous forms at the far back of the skull. Modern humans have a brain size comparable to that of Neanderthals; however, our brain expansion occurred in the frontal region of the brain, not the back, as in Neanderthal brains. This difference is also the main reason why Neanderthals lack the vertical forehead that modern humans possess. They simply did not need an enlarged forehead, because their brain expansion occurred in the rear of their brain. Due to cranial expansion, the back of the Neanderthal skull is less angular (as compared to <em>Homo erectus<\/em>), but not as rounded as <em>Homo sapiens<\/em>, producing an elongated shape, akin to a football.<\/p>\n<p class=\"import-Normal\">Another feature that continues the trend noted in previous hominins is the enlargement of the nasal region, or the nose. Neanderthal noses are large and have a wide nasal aperture, which is the opening for the nose. While the nose is only made up of two bones, the nasals, the true size of the nose can be determined by looking at other facial features, including the nasal aperture, and the angle of the nasal and maxillary, or facial bones. In Neanderthals, these indicate a large, forward-projecting nose that appears to be pulled forward away from the rest of the face. This feature is further emphasized by the backward-sloping nature of the cheekbones, or the zygomatic arches. The unique shape and size of the Neanderthal nose is often characterized by the term <em>midfacial prognathism<\/em>\u2014a jutting out of the middle portion of the face, or nose. This is in sharp contrast to the prognathism exhibited by other hominins, who exhibited prognathism, or the jutting out, of their jaws.<\/p>\n<p class=\"import-Normal\">The teeth of the Neanderthals follow a similar pattern seen in the Archaic <em>Homo sapiens<\/em>, which is an overall reduction in size, especially as compared to the extremely large teeth seen in the genus <em>Australopithecus<\/em>. However, while the teeth continued to reduce, the jaw size did not keep pace, leaving Neanderthals with an oversized jaw for their teeth, and a gap between their final molar and the end of their jaw. This gap is called a <strong>retromolar gap<\/strong>.<\/p>\n<p class=\"import-Normal\">The projecting occipital bone present in other Archaic<em> Homo sapiens <\/em>is also more prominent in Neanderthals, extending the trend found in Archaics. Among Neanderthals, this projection of bone is easily identified by its bun shape on the back of the skull and is known as an <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1645\">occipital bun<\/a><\/strong>. This projection appears quite similar to a dinner roll in size and shape. Its purpose, if any, remains unknown.<\/p>\n<p class=\"import-Normal\">Continuing the Archaic<em> Homo sapiens <\/em>trend, Neanderthal brow ridges are prominent but somewhat smaller in size than those of <em>Homo <\/em><em>erectus<\/em> and earlier Archaic<em> Homo sapiens. <\/em>In Neanderthals, the brow ridges are also often slightly less arched than those of other Archaic<em> Homo sapiens<\/em>.<\/p>\n<p class=\"import-Normal\">In addition to extending traits present in Archaic<em> Homo sapiens, <\/em>Neanderthals possess several distinct traits. Neanderthal <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1646\">infraorbital foramina<\/a><\/strong>, the holes in the maxillae or cheek bones through which blood vessels pass, are notably enlarged compared to other hominins. The Neanderthal postcrania are also unique in that they demonstrate increased robusticity in terms of the thickness of bones and body proportions that show a barrel-shaped chest and short, stocky limbs, as well as increased musculature. These body portions are seen across the spectrum of Neanderthals\u2014in men, women, and children.<\/p>\n<p class=\"import-Normal\">Traditionally, many of the unique traits that Neanderthals possess were seen as adaptations to the extreme cold, dry environments in which they often lived and which exerted strong selective forces. For example, Bergmann\u2019s and Allen\u2019s Rules dictate that an increased body mass and short, stocky limbs are common in animals that live in cold conditions. Neanderthals were said to have matched the predictions of Bergmann\u2019s and Allen\u2019s Rules perfectly (Churchill 2006). In addition, the Neanderthal skull also exhibits adaptations to the cold. Neanderthals\u2019 large infraorbital foramina allow for larger blood vessels, increasing the volume of blood that is found closest to the skin, which helps to keep the skin warmer. Their enlarged noses resulted in longer nasal passages and mucus membranes that warmed and moistened cold air before it reached the lungs. The Neanderthals\u2019 larger nose has long been thought to have acted as a humidifier, easing physical exertion in their climate, although research on this particular trait continues to be studied and debated (Rae Et al. 2011).<\/p>\n<p class=\"import-Normal\">New research, however, seems to suggest that these unique skeletal adaptations might not have been strict adaptations to cold weather (Evteev Et al. 2017; Pearce Et al. 2013). For example, large brow ridges might have served as a way to shade the face from the sun. The increased occipital portion of the brain, some researchers state, was to support a larger visual system present in Neanderthals. This visual system would have given them increased light sensitivity, which would have been useful in higher latitudes that had dark winters. And, while recent modeling of nostril airflow on reconstructed Neanderthal specimens supports the notion that Neanderthals had extensive mucus membranes inside their noses, the data shows that modern <em>Homo sapiens<\/em> are superior to Neanderthals in our ability to use our noses as a way to warm and cool air. However, Neanderthals were able to snort air through their noses better than we can. Why is this important? When combined with the fact that Neanderthals tended to prefer a more temperate, tundra-like environment, and that other physical traits suggest that Neanderthals had huge bodies that needed massive amounts of calories to sustain them, the picture gets clearer. Massive amounts of energy would have been required to power a Neanderthal body, and anything that might have made them more calorically efficient would have been favoured. Efficient breathing, through larger noses into large lungs, meaning deeper breaths, would have been favoured. To further save energy expenditure, body sizes might have been sacrificed as well. These same types of adaptations are similar to ones seen in children today who are born in high altitudes, not cold climates. Figure 12.7 provides a summary of these unique features of the Neanderthal.<\/p>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<caption>Figure 12.7: Neanderthal distinguishing features. This table outlines key features associated with Neanderthals. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-16\/\" target=\"_blank\">Neanderthal distinguishing features table (Figure 11.6)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Amanda Wolcott Paskey and AnnMarie Beasley Cisneros is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/caption>\n<thead>\n<tr style=\"height: 21pt\">\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\" colspan=\"2\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Distinct Neanderthal Anatomical Features<\/strong><\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Brain Size<\/strong><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1,500 cc average<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Skull Shape<\/strong><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Long and low<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Brow Ridge Size<\/strong><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Large<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Nose Size<\/strong><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Large, with midfacial prognathism<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dentition<\/strong><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Reduced, but large jaw size, creating retromolar gap<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Occipital Region<\/strong><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Enlarged occipital region, occipital bun<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Other Unique Cranial Features<\/strong><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Large infraorbital foramina<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Postcranial Features<\/strong><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Short and stocky body, increased musculature, barrel-shaped chest<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<p class=\"import-Normal\">A classic example of a Neanderthal with all of the characteristics mentioned above is the nearly complete La Ferrassie 1 Neanderthal, from France. This is a male skeleton, with a brain size of around 1640cc, an extremely large nose and infraorbital foramina, brow ridges that are marked in size, and an overall robust skeleton (Figure 12.8).<\/p>\n<p>&nbsp;<\/p>\n<figure style=\"width: 390px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image1-4.png\" alt=\"A reproduction of a complete Neanderthal skeleton.\" width=\"390\" height=\"689\" \/><figcaption class=\"wp-caption-text\">Figure 12.8: La Ferrassie 1 Neanderthal is representative of many classic Neanderthal features, including a large brain, large nose, large infraorbital foramina, large brow ridges, and robust postcrania. Credit: <a href=\"https:\/\/boneclones.com\/product\/neanderthal-skeleton-articulated-SC-019-A\" target=\"_blank\">Neanderthal Skeleton Articulated<\/a> by <a href=\"https:\/\/boneclones.com\/\" target=\"_blank\">\u00a9BoneClones<\/a> is used by permission and available here under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<h3 class=\"import-Normal\"><strong>Neanderthal Culture: Tool Making and Use<\/strong><\/h3>\n<p class=\"import-Normal\">One key Neanderthal adaptation was their cultural innovations, which are an important way that hominins adapt to their environment. As you recall, <em>Homo erectus<\/em>'s tools, Acheulean handaxes, represented an increase in complexity over Oldowan tools, allowing more efficient removal of meat and possibly calculated scavenging. In contrast, Neanderthal tools mark a significant innovation in tool-making technique and use with <strong>Mousterian tools<\/strong> (named after the Le Moustier site in southwest France). These tools were significantly smaller, thinner, and lighter than Acheulean handaxes and formed a true toolkit. The materials used for Mousterian tools were of higher quality, which allowed for both more precise toolmaking and tool reworking when the tools broke or dulled after frequent reuse. The use of higher-quality materials is also indicative of required forethought and planning to acquire them for tool manufacture. It has been suggested that the Neanderthals, unlike <em>Homo <\/em><em>erectus<\/em>, saved and reused their tools, rather than making new ones each time a tool was needed.<\/p>\n<figure style=\"width: 290px\" class=\"wp-caption alignright\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image3-4.png\" alt=\"Large flakes separated from the core.\" width=\"290\" height=\"159\" \/><figcaption class=\"wp-caption-text\">Figure 12.9: The Levallois technique is used to create Mousterian tools. The multistep process involves preparing the core in a specific way to yield flakes that can be used as tools. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Nucl%C3%A9us_Levallois_La-Parrilla.png\" target=\"_blank\">Nucl\u00e9us Levallois La-Parrilla<\/a> by Jos\u00e9-Manuel Benito \u00c1lvarez is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.5\/legalcode\" target=\"_blank\">CC BY-SA 2.5 License<\/a>..<\/figcaption><\/figure>\n<p>Mousterian tools are constructed in a very unique manner, utilizing the <strong>Levallois technique<\/strong> (Figure 12.9), named after the first finds of tools made with this technique, which were discovered in the Levallois-Perret suburb of Paris, France. The Levallois technique is a multistep process that requires preparing the core, or raw material, in a specific way that will yield flakes that are roughly uniform in dimension. The flakes are then turned into individual tools. The preparation of the core is akin to peeling a potato or carrot with a vegetable peeler\u2014when peeling vegetables, you want to remove the skin in long, regular strokes, so that you are taking off the same amount of the vegetable all the way around. In the same way, the Levallois technique requires removing all edges of the <strong>cortex<\/strong>, or outside surface of the raw material, in a circle before removing the lid. The flakes, which will eventually be turned into the individual tools, can then be removed from the core. The potential yield of tools from one core would be many, as seen in Figure 12.10, compared to all previous tool-making processes, in which one core yielded a single tool. This manufacturing process might be considered the ultimate zero-waste tool-making technique (Delpiano Et al. 2018).<\/p>\n<figure style=\"width: 589px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image19-4.png\" alt=\"Levallois core and flakes that are gray in color and various shapes and sizes.\" width=\"589\" height=\"470\" \/><figcaption class=\"wp-caption-text\">Figure 12.10: Levallois core and flakes for tool production. Using this technique, one core is used to produce many flakes, each of which can be turned into a tool. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:NHM_-_Levalloiskern.jpg\" target=\"_blank\">NHM - Levalloiskern<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Xenophon\" target=\"_blank\">Wolfgang Sauber<\/a> (user: Xenophon) is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\" target=\"_blank\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">It is suggested that Neanderthal tools were used for a variety of purposes, including cutting, butchering, woodworking or antler working, and hide working. Additionally, because the Mousterian tools were lighter than previous stone tools, Neanderthals could <strong>haft<\/strong>, or attach the tool onto a handle, as the stone would not have been too heavy (Degano Et al. 2019). Neanderthals attached small stone blades onto short wood or antler handles to make knives or other small weapons, as well as attached larger blades onto longer shafts to make spears. New research examining tar-covered stones and black lumps at several Neanderthal sites in Europe suggests that Neanderthals may have been making tar by distilling it from birch tree bark, which could have been used to glue the stone tool onto its handle. If Neanderthals were, in fact, manufacturing tar to act as glue, this would predate modern humans in Africa using tree resin or similar adhesives by nearly 100,000 years.<\/p>\n<p class=\"import-Normal\">Evidence shows that raw materials used by Neanderthals came from distances as far away as 100 km. This could indicate a variety of things regarding Neanderthal behaviour, including a limited trade network with other Neanderthal groups or simply a large area scoured by Neanderthals when collecting raw materials. While research on specific applications continues, it should be clear from this brief discussion that Neanderthal tool manufacturing was much more complex than previous tool-making efforts, requiring technical expertise, patience, and skills beyond toolmaking to carry out.<\/p>\n<h3 class=\"import-Normal\"><strong>Neanderthal Culture: Hunting and Diet<\/strong><\/h3>\n<p class=\"import-Normal\">With their more sophisticated suite of tools and robust muscular bodies, Neanderthals were better armed for hunting than previous hominins. The animal remains in Neanderthal sites show that, unlike earlier Archaic <em>Homo sapiens<\/em>, Neanderthals were very effective hunters who were able to kill their own prey, rather than relying on scavenging. Though more refined than the tools of earlier hominins, the Neanderthal spear was not the kind of weapon that would have been thrown; rather, it would have been used in a jabbing fashion (Churchill 1998; Kortlandt 2002). This may have required Neanderthals to hunt in groups rather than individually and made it necessary to approach their prey quite closely (Gaudzinski-Windheuser Et al. 2018). Remember, the animals living with Neanderthals were very large-bodied due to their adaptations to cold weather; this would have included species of deer, horses, and bovids (relatives of the cow).<\/p>\n<p class=\"import-Normal\">Isotopes from Neanderthal bones show that meat was a significant component of their diet, similar to that seen in carnivores like wolves (Bocherens Et al. 1999; Jaouen Et al. 2019; Richards Et al. 2000). In addition to large prey, their diet included ibex, seals, rabbits, and pigeons. Though red meat was a critical component of the Neanderthal diet, evidence shows that at times they also ate limpets, mussels, and pine nuts. Tartar examined from Neanderthal teeth in Iraq and Belgium reveal that they also ate plant material including wheat, barley, date palms, and tubers, first cooking them to make them palatable (Henry Et al. 2010). While Neanderthals\u2019 diet varied according to the specific environment in which they lived, meat comprised up to 80% of their diet (Wi\u1e9ein Et al. 2015).<\/p>\n<h3 class=\"import-Normal\"><strong>Neanderthal Culture: Caring for the Injured and Sick<\/strong><\/h3>\n<p class=\"import-Normal\">While the close-range style of hunting used by Neanderthals was effective, it also had some major consequences. Many Neanderthal skeletons have been found with significant injuries, which could have caused paralysis or severely limited their mobility. Many of the injuries are to the head, neck, or upper body. Thomas Berger and Erik Trinkaus (1995) conducted a statistical comparative analysis of Neanderthal injuries compared to those recorded in modern-day workers\u2019 compensation reports and found that the closest match was between Neanderthal injuries and those of rodeo workers. Rodeo professionals have a high rate of head and neck injuries that are similar to the Neanderthals\u2019 injuries. What do Neanderthals and rodeo workers have in common? They were both getting very close to large, strong animals, and at times their encounters went awry.<\/p>\n<p class=\"import-Normal\">The extensive injuries sustained by Neanderthals are evident in many fossil remains. Shanidar 1 (Figure 12.11), an adult male found at the Shanidar site in northern Iraq and dating to 45,000 ya, has a lifetime of injuries recorded in his bones (Stewart 1977). Shanidar 1 sustained\u2014and healed from\u2014an injury to the face that would have likely caused blindness. His lower right arm was missing and the right humerus shows severe atrophy, likely due to disuse. This pattern has been interpreted to indicate a substantial injury that required or otherwise resulted in amputation or wasting away of the lower arm. Additionally, Shanidar 1 suffered from bony growths in the inner ear that would have significantly impaired his hearing and severe arthritis in the feet. He also exhibited extensive anterior tooth wear, matching the pattern of wear found among modern populations who use their teeth as a tool. Rather than an anomaly, the type of injuries evident in Shanidar 1 are similar to those found in many other Neanderthal fossils, revealing injuries likely sustained from hunting large mammals as well as demonstrating a long life of physical activity.<\/p>\n<p>&nbsp;<\/p>\n<p><img class=\"aligncenter\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image11-4.png\" alt=\"Neaderthal skull.\" width=\"329\" height=\"329\" \/><\/p>\n<figure style=\"width: 330px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image5-4.png\" alt=\"Neaderthal right and left humerus. The right humerus is withered looking.\" width=\"330\" height=\"330\" \/><figcaption class=\"wp-caption-text\">Figure 12.11a-b: a. The Shanidar 1 skull shows an injury to the face that would likely have caused blindness. b. The Shanidar 1 right humerus (on the left side of the image) shows severe atrophy, likely due to disuse. Credit: a. <a href=\"https:\/\/boneclones.com\/product\/shanidar-1-skull-BH-050\" target=\"_blank\">Homo neanderthalensis Shanidar 1 Skull<\/a> by <a href=\"https:\/\/boneclones.com\/\" target=\"_blank\">\u00a9BoneClones<\/a> is used by permission and available here under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>. b. <a href=\"https:\/\/humanorigins.si.edu\/evidence\/human-fossils\/fossils\/shanidar-1\" target=\"_blank\">Shanidar 1<\/a> by Chip Clark, <a href=\"https:\/\/www.si.edu\/\" target=\"_blank\">Smithsonian Institution<\/a> [exhibit: <a href=\"https:\/\/humanorigins.si.edu\/research\" target=\"_blank\">Human Evolution <\/a>Evidence, Human Fossils, Species, Homo neanderthalensis] <a href=\"https:\/\/www.si.edu\/termsofuse\" target=\"_blank\">is used for educational and non-commercial purposes as outlined by the Smithsonian.<\/a><\/figcaption><\/figure>\n<p class=\"import-Normal\">The pattern of injuries is as significant as the fact that Shanidar 1 and other injured Neanderthals show evidence of having <em>survived<\/em> their severe injuries. One of the earliest-known Neanderthal discoveries\u2014the one on whom misinformed analysis shaped the stereotype of the species for nearly a century\u2014is the La Chapelle-aux-Saints Neanderthal (Trinkaus 1985). The La Chapelle Neanderthal had a damaged eye orbit that likely caused blindness and suffered arthritis of the spine (Dawson and Trinkaus 1997). He had also lost most of his teeth, many of which he had lived without for so long that the mandibular and maxillary bones were partially reabsorbed due to lack of use. The La Chapelle Neanderthal was also thought to be at least in his mid-forties at death, an old age for the rough life of the Late Pleistocene\u2014giving rise to his nickname, \u201cthe Old Man.\u201d To have survived so long with so many injuries that obviously precluded successful large game hunting, he must have been taken care of by others. Such caretaking behaviour is also evident in the survival of other seriously injured Neanderthals, such as Shanidar 1. Long thought to be a hallmark modern human characteristic, taking care of the injured and elderly, for example preparing or pre-chewing food for those without teeth, indicates strong social ties among Neanderthals.<\/p>\n<h3 class=\"import-Normal\"><strong>Neanderthal Culture: Ritual Life<\/strong><\/h3>\n<p class=\"import-Normal\">Such care practices may have been expressed upon death as well. Nearly complete Neanderthal skeletons are not uncommon in the fossil record, and most are well preserved within apparently deliberate burials that involve deep graves and bodies found in specific, often fetal or <strong>flexed positions<\/strong> (Harrold 1980)<strong>.<\/strong> Discoveries of pollen in a grave at the Shanidar site in the 1960s led scientists to think that perhaps Neanderthals had placed flowering plants in the grave, an indication of ritual ceremony or spirituality so common in modern humans. But more recent investigations have raised some doubt about this conclusion (Pomeroy Et al. 2020). The pollen may have been brought in by burrowing rodents. Claims of <strong>grave goods<\/strong> or other ornamentation in burials are similarly debated, although possible.<\/p>\n<p class=\"import-Normal\">Some tantalizing evidence for symbolism, and debatably, ritual, is the frequent occurrence of natural pigments, such as <strong>ochre<\/strong> (red) and manganese dioxide (black) in Neanderthal sites that could have been used for art. However, the actual uses of pigments are unclear, as there is very little evidence of art or paintings in Mousterian sites. One exception may be the recent discovery in Spain of a perforated shell that appears to be painted with an orange pigment, which may be evidence of Neanderthal art and jewelry. However, many pigments also have properties that make them good emulsifiers in adhesive (like for attaching a stone tool to a wooden handle) or useful in tanning hides. So the presence of pigment may or may not be associated with symbolic thought; however, it definitely does show a technological sophistication beyond that of earlier Archaic hominins.<\/p>\n<div class=\"textbox shaded\" style=\"background: var(--lightblue)\">\n<h2>Dig Deeper: Evidence of Endocannibalism Among the Neanderthals<\/h2>\n<p>Krapina, a Neanderthal site in Croatia, has recently sparked new archeological discourse as many investigations upon fossilized remains show evidence of post-mortem modifications and manipulations of limbs and bones through the use of tools (Rougier Et al., 2016). These findings provide compelling evidence of Neanderthals engaging in cannibalism as part of their post-mortem practices. Additionally, these uncovered remains were found to have died of natural causes as opposed to being killed, showing that even the earliest humans may have had some sort of morality or ethics surrounding the cannibalizing of their kin, meaning they were aware of death in a social context as opposed to merely a physical one.<\/p>\n<p>While the original evidence in Krapina was uncovered in 1901, Croatian geologist and paleontologist Dragutin Gorjanovi\u0107-Kramberger\u2019s discovery of fragmented and burned human bones (Ullrich, 2005) was not yet confirmed to be linked to endocannibalism until much later. Whereas the discovery of burned bones does not mean they were being prepared for consummation, due to its context among other findings, this information supports the hypothesis that early hominids conducted post-mortem rituals and practices with their dead. Building on Gorjanovi\u0107-Kramberger\u2019s research, Herbert Ullrich wrote in <em>Anthropologie<\/em> (2005) that broken bones\u2014resulting from post-mortem bodily manipulations\u2014were \u201cdefleshed in preparation for secondary burial\u201d (2005, 251) and intentionally left outside rock shelters, while selectively chosen bones were seemingly brought inside for use in mortuary practices.<\/p>\n<p>For nearly 150 years, since the first Neanderthal skeletal remains were discovered, anthropologists and researchers have continued to debate the cognitive, social, and physical abilities of this species. In 2016, Rougier and colleagues wrote in <em>Scientific Reports<\/em>, furthering the research, presenting 99 new Neanderthal remains found in Goyet, Belgium. Among these remains, similar evidence of human-induced alterations was identified, including signs of butchering, consumption, and the use of bones to modify stone tools (Rougier Et al., 2016). This discovery provides significant support for the presence of cannibalistic behaviour among Northern European Neanderthals, contributing to the growing body of evidence that Neanderthals engaged with death in ways that reflect social awareness, ritual behaviour, and complex cultural practices.<\/p>\n<p><strong>Contemporary Cases of Prion Disease Related to Endocannibalism<\/strong><\/p>\n<p>The evidence of endocannibalism does not end with early hominids; with Australian medical anthropologists recording thousands of cannibalism-related prion disease occurrences present in populations up until 2009 (Radford &amp; Scragg, 2013). Following a mysterious epidemic of a new form of spongiform encephalopathy\u2013a \u201cprogressive degenerative disease of the central nervous system\u201d (2013, p.29)\u2013anthropological research regarding the the cultural mortuary rites within the Okapa region of Papua New Guinea have linked the newfound disease \u2018Kuru\u2019 to post-mortem consumption of human remains (Radford &amp; Scragg, 2013; Collinge Et al., 2006).<\/p>\n<p>Local oral histories collected during the first investigations by these researchers in the 1950s traced the earliest cases back to the 1920s, with detailed case histories. Epidemiological data revealed a strong correlation between the spread of Kuru and participation in mortuary feasts, in which the deceased were ritually consumed as part of funerary rites (2006, p. 2070). From 1957 to 2004, over 2,700 cases were reported, with mortality peaking at over 200 deaths annually in the late 1950s (2006, p.2070); however, following the cessation of cannibalism in the easly 1960s due to governmental efforts, natural transmission of the disease has stopped, dropping the death toll dramatically, with the \u201clast three single cases reported in 2005, 2007, and 2009\u201d (Radford &amp; Scragg, p.48).<\/p>\n<\/div>\n<h3 class=\"import-Normal\"><strong>The Lasting Gift of Neanderthals: Tantalizing New Directions for Resear<\/strong><strong>ch<\/strong><\/h3>\n<p class=\"import-Normal\">Examining the more recent time period in which Neanderthals lived and the extensive excavations completed across Europe allows for a much more complete archaeological record from this time period. Additionally, the increased cultural complexity such as complex tools and ritual behaviours expressed by Neanderthals left a more detailed record than previous hominins. Intentional burials enhanced preservation of the dead and potentially associated ritual behaviours. Such evidence allows for a more complete and nuanced picture of this species.<\/p>\n<figure style=\"width: 424px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image15-5.png\" alt=\"Museum exhibition of life-sized Neanderthal figure.\" width=\"424\" height=\"469\" \/><figcaption class=\"wp-caption-text\">Figure 12.12: Artistic reconstruction of Neanderthal at The Natural History Museum in Vienna, Austria. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Homo_neanderthalensis,_The_Natural_History_Museum_Vienna,_20210730_1223_1272.jpg\" target=\"_blank\">Homo neanderthalensis, The Natural History Museum Vienna, 20210730 1223 1272<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Jakubhal\" target=\"_blank\">Jakub Ha\u0142un<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/legalcode\" target=\"_blank\">CC BY 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Additional analyses are possible on many Neanderthal finds, due to increased preservation of bone, the amount of specimens that have been uncovered, and the recency in which Neanderthals lived. We should be cautious, however, to consider the potential bias of many Neanderthal sites. Overwhelmingly, Neanderthal skeletons are found complete, with injuries or evidence of disease in caves. Does this mean all Neanderthals lived a tough, disease-wrought life? Probably not. It does, however, indicate that the sick were cared for by others, and that they lived in environments that preserved their bodies incredibly well. These additional studies include the examination of dental calculus and even DNA analysis. While limited, samples of Neanderthal DNA have been successfully extracted and analysed. Research thus far has identified specific genetic markers that show some Neanderthals were light-skinned and probably red-haired with light eyes. Genetic analyses, different from the typical hominin reconstruction done with earlier species, allow scientists to further investigate soft tissue markers of Neanderthals and other more recent hominin species. These studies offer striking conclusions regarding Neanderthal traits, their physical appearance, and their culture, as reflected in these artists\u2019 reconstructions (Figure 12.12).<\/p>\n<figure style=\"width: 258px\" class=\"wp-caption alignright\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image17-4.png\" alt=\"Photograph of Dr. Svante P\u00e4\u00e4bo in a blue suit and red tie.\" width=\"258\" height=\"368\" \/><figcaption class=\"wp-caption-text\">Figure 12.13: Nobel Prize winner (2022) and pioneer in paleogenomic research, Dr. Svante P\u00e4\u00e4bo. Credit: <a href=\"https:\/\/upload.wikimedia.org\/wikipedia\/commons\/2\/26\/Professor_Svante_Paabo_ForMemRS_%28cropped%29.jpg\" target=\"_blank\">Professor Svante Paabo ForMemRS (cropped)<\/a> by Duncan.Hull is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Dr. Svante P\u00e4\u00e4bo (Figure 12.13), of the Max Planck Institute for Evolutionary Anthropology, has been at the forefront of much of this new research, largely in the form of genomic studies (The Nobel Prize 2022). Awarded the Nobel Prize for Physiology or Medicine in 2022, P\u00e4\u00e4bo is known primarily for his work with ancient DNA. He has successfully sequenced mitochondrial DNA (mtDNA) as well as the entire Neanderthal genome from nuclear DNA. His genomic work has led to the realization that Denisovans are genetically distinct from Neanderthals, as well as the recent identification of a Neanderthal father and teenage daughter, which he discovered by looking for unique DNA markers in the fossil record. Additionally, P\u00e4\u00e4bo\u2019s genomic work has provided researchers with additional lines of evidence regarding the connections between hominin fossils (such as Neanderthals) and modern people, their time of divergence, and current genetic overlap. The work of P\u00e4\u00e4bo has even formalized a new field of study within anthropology\u2014paleogenomics. To stay up to date with Dr. Svante P\u00e4\u00e4bo\u2019s work, be sure to follow his <a href=\"https:\/\/www.eva.mpg.de\/genetics\/neandertals-and-more\/overview\/\" target=\"_blank\">lab\u2019s website<\/a>.<\/p>\n<h3 class=\"import-Normal\"><strong>Neanderthal Culture: Communicating through Speech<\/strong><\/h3>\n<p class=\"import-Normal\">To successfully live in groups and to foster cultural innovations, Neanderthals would have required at least a basic form of communication in order to function, possibly using a speech-based communication system. The challenge with this line of research is that speech, of course, is not preserved, so indirect evidence must be used to support this conclusion. It is thought that Neanderthals would have possessed some basic speech, as evidenced from a variety of sources, including throat anatomy and genetic evidence (Lieberman 1971). There is only one bone in the human body that could demonstrate if a hominin was able to speak, or produce clear vocalizations like modern humans, and that is the hyoid, a U-shaped bone that is found in the throat and is associated with the ability to precisely control the vocal cords. Very few hyoid bones have been found in the archaeological record; however, a few have been uncovered in Neanderthal burials. The shape of the Neanderthal hyoid is nearly identical to that of modern humans, pointing to the likelihood that they had the same vocal capabilities as modern humans. In addition, geneticists have uncovered a mutation present in both modern humans and Neanderthals\u2014the FOXP2 gene\u2014that is possibly linked to the ability to speak. However, other scientists argue that we cannot make sweeping conclusions that the FOXP2 gene accounts for speech due to small sample size. Finally, scientists have also pointed to the increasingly complex cultural behaviour of Neanderthals as a sign that symbolic communication, likely through speech, would have been the only way to pass down the skills needed to make, for example, a Levallois blade or to position a body for intentional burial.<\/p>\n<h3 class=\"import-Normal\"><strong>Neanderthal Intelligence<\/strong><\/h3>\n<p class=\"import-Normal\">One of the enduring questions about Neanderthals centres on their intelligence, specifically in comparison to modern humans. Brain volume indicates that Neanderthals certainly had a large brain, but it continues to be debated if Neanderthals were of equal intelligence to modern humans. Remember, creatures with larger body sizes tend to have larger brains; however, scaling of the brain is not always associated with greater intelligence (Alex 2018). Brain volume (cranial capacity), cultural complexity, tool use, and compassion toward their kind all point to an increase in intellect among Neanderthals when compared to previous hominins.<\/p>\n<p class=\"import-Normal\">Yet, new research is suggesting additional differences between Neanderthal brains and our own. For example, Euluned Pearce and colleagues (2013), from the University of Oxford, noted the frontal lobes of Neanderthals and modern humans are almost identical. However, Neanderthals had a larger visual cortex\u2014the portion of the brain involved in processing visual information. This would have left Neanderthals with less brain tissue for other functions, including those that would have aided them in dealing with large social groupings, one of the differences that has been suggested to exist between Neanderthals and modern humans. Other differences were found when geneticist John Blangero, from the Texas Biomedical Research Institute, compared data from the Neanderthal genome against data from modern study participants. Blangero and his colleagues (Blangero Et al. 2014) discovered that some Neanderthal brain components were very different, and smaller, than those in the modern sample. Differences were found in areas associated with the processing of information and controlling emotion and motivation, as well as overall brain connectivity. In short, as Blangero stated, \u201cNeanderthals were certainly cognitively adept,\u201d although their specific abilities may have differed from modern humans\u2019 in key areas (qtd. in Wong 2015). This point has been echoed in other recent genetic studies comparing Neanderthal and anatomically modern human brains (el-Showk 2019).<\/p>\n<p class=\"import-Normal\">Finally, scientists are fairly certain that Neanderthal brain development after birth was not the same as that of modern humans. After birth, anatomically modern <em>Homo sapiens <\/em>babies go through a critical period of brain expansion and cognitive development. It appears that Neanderthal babies\u2019 brains and bodies did not follow the same developmental pattern (Smith Et al. 2010; Zollikofer and Ponce de Le\u00f3n 2013). Modern humans enjoy an extended period of childhood, which allows children to engage in imaginative play and develop creativity that fosters cognitive skills. Neanderthals had a more limited childhood, with less development of the creative mind that may have affected their species\u2019 success (Nowell 2016).<\/p>\n<p class=\"import-Normal\">The exact nature of Neanderthal intelligence remains under investigation, however. Some studies disagree with the idea that Neanderthal intelligence had limitations compared to our own, noting the extensive evidence of Neanderthals having limb asymmetry. Their tools also have wear marks indicating that they were hand-dominant. This is further supported by marks on Neanderthal teeth that demonstrate hand dominance. The Neanderthal \u201cstuff-and-cut method\u201d of eating, noted by David Frayer and colleagues (Frayer Et al. 2012), would have seen Neanderthals hold a piece of meat in their teeth, while pulling it taut with one hand, and then using the other hand, their dominant one, to cut the meat off of the larger slab being held in their teeth. When looking at 17 Neanderthals and their tooth wear, only two do not show markings associated with a right-hand dominant individual eating in this manner. Further, it has been established that favouring the right hand is a key marker between modern humans and chimpanzees, and that handedness also relates to language development, in the form of bilateral brain development. That Neanderthals likely were hand-dominant suggests they had an indicator of bilateral brain development and a precondition for human speech.<\/p>\n<h2 class=\"import-Normal\">The Middle Stone Age: Neanderthal Contemporaries in Africa<\/h2>\n<p class=\"import-Normal\">While Neanderthals made their home on and adapted to the European and Asian continents, evidence of fossil humans in Africa show they were also adapting to their local environments. These populations in Africa exhibit many more similarities to modern humans than Neanderthals, as well as overall evolutionary success. While the African fossil sample size is smaller and more fragmentary than the number of Neanderthal specimens across Europe and Asia, the African sample is interesting in that it represents a longer time period and larger geographical area. This group of fossils\u2014often represented by the name \u201cMiddle Stone Age,\u201d or MSA\u2014dates to between 300,000 and 30,000 years ago across the entire continent of Africa. As with Archaic <em>Homo sapiens<\/em>, there is much variability seen in this African set of fossils. There are also a few key consistent elements: none of them exhibit Neanderthal skeletal features; instead, they demonstrate features that are increasingly consistent with anatomically modern <em>Homo sapiens<\/em>.<\/p>\n<p class=\"import-Normal\">Similarities to Neanderthals and MSA contemporaries in Africa are seen, however, in their behavioural adaptations, including stone tools and other cultural elements. The tools associated with the specimens living in Africa during this time period are, like their physical features, varied. In some parts of Africa, namely Northern Africa, stone tools from this time so closely resemble Neanderthal tools that they are classified as Mousterian. In sub-Saharan Africa, the stone tools associated with these specimens are labeled as MSA. Some scholars argue that these could also be a type of Mousterian tools, but they are still typically subdivided based on geographical location.<\/p>\n<p class=\"import-Normal\">Recall that Mousterian tools were much more advanced than their Acheulean predecessors in terms of how the stone tools were manufactured, the quality of the stones used, and the ultimate use of the tools that were made. In addition, recent evidence suggests that MSA tools may also have been heat treated\u2014to improve the quality of the stone tool produced (Stolarczyk and Schmidt 2018). Evidence for heat treating is seen not only through advanced analysis of the tool itself but also through the residue of fires from this time period. Fire residues show a shift over time from small, short fires fuelled by grasses (probably intended for cooking) to larger, more intensive fires that required the exploitation of dry wood, exactly the type of fire that would have been needed for heat treating stone tools (Esteban Et al. 2018).<\/p>\n<p class=\"import-Normal\">Other cultural elements seen with MSA specimens include the use of marine (sea-based) resources for their diet (Parkington 2003), manufacture of bone tools, use of adhesive and compound tools (e.g., hafted tools), shell bead production, engraving, use of pigments (such as ochre), and other more advanced tool-making technology (e.g., microlithics). While many of these cultural elements are also seen to a limited extent among Neanderthals, developments at MSA sites appear more complex. This MSA cultural expansion may have been a response to climate change or an increased use of language, complex communication, and\/or symbolic thought. Others have suggested that the MSA cultural expansion was due to the increase of marine resources in their diet, which included more fatty acids that may have aided their cognitive development. Still others have suggested that the increased cultural complexity was due to increased interaction among groups, which spurred competition to innovate. Recent studies suggest that perhaps the best explanation for the marked cultural complexity of MSA cultural artifacts is best explained by the simple fact that they lived in diverse habitats (Kandel Et al. 2015). This would have necessitated a unique set of cultural adaptations for each habitat type (for example, specialized marine tools would have been needed along coastal sites but not at inland locations). Simply put, the most useful adaptation of MSA was their flexibility of behaviour and adaptability to their local environment. As noted previously in this chapter, flexibility of behaviour and physical traits, rather than specialization, seems to be a feature that was favoured in hominin evolution at this time.<\/p>\n<h2 class=\"import-Normal\">Where Did They Go? The End of Neanderthals<\/h2>\n<p class=\"import-Normal\">While MSA specimens were increasingly successful and ultimately transitioned into modern <em>Homo sapiens<\/em>, Neanderthals disappeared from the fossil record by around 40,000 years ago. What happened to them? We know, based on genetics, that modern humans come largely from the modern people who occupied Africa around 300,000 to 100,000 years ago, at the same time that Neanderthals were living in northern Europe and Asia. As you will learn in Chapter 13, modern humans expanded out of Africa around 150,000 years ago, rapidly entering areas of Europe and Asia inhabited by Neanderthals and other Archaic hominins. Despite intense interest and speculation in fictional works about possible interactions between these two groups, there is very little direct evidence of either peaceful coexistence or aggressive encounters. It is clear, though, that these two closely related hominins shared Europe for thousands of years, and recent DNA evidence suggests that they occasionally interbred (Fu Et al. 2015). Geneticists have found traces of Neanderthal DNA (as much as 1% to 4%) in modern humans of European and Asian descent not present in modern humans from sub-Saharan Africa. This is indicative of limited regional interbreeding with Neanderthals.<\/p>\n<p class=\"import-Normal\">While some interbreeding likely occurred, as a whole, Neanderthals did not survive. What is the cause for their extinction? This question has fascinated many researchers and several theories have been suggested, including:<\/p>\n<ul>\n<li class=\"import-Normal\">At the time that Neanderthals were disappearing from the fossil record, the climate went through both cooling and warming periods\u2014each of which posed challenges for Neanderthal survival (Defleur and Desclaux 2019; Staubwasser Et al. 2018). It has been argued that as temperatures warmed, large-bodied animals, well adapted to cold weather, moved farther north to find colder environments or faced extinction. A shifting resource base could have been problematic for continued Neanderthal existence, especially as additional humans, in the form of modern <em>Homo sapiens<\/em>, began to appear in Europe and compete for a smaller pool of available resources.<\/li>\n<li class=\"import-Normal\">It has been suggested that the eruption of a European volcano 40,000 years ago could have put a strain on available plant resources (Golovanova Et al. 2010). The eruption would have greatly affected local microclimates, reducing the overall temperature enough to alter the growing season.<\/li>\n<li class=\"import-Normal\">Possible differences in cognitive development may have limited Neanderthals in terms of their creative problem solving. As much as they were biologically specialized for their environment, the nature of their intelligence might not have offered them the creative problem-solving skills to innovate ways to adapt their culture when faced with a changing environment (Pearce Et al. 2013).<\/li>\n<li class=\"import-Normal\">CRISPR gene-editing technology has been used in studies to evaluate potential differences between human and Neanderthal brains, based on differences in the genetic code. Potential differences include a Neanderthal propensity for mutations related to brain development that could account for more rapid brain development, maturation, synapse misfires, and less-orderly neural processes (Mora-Berm\u00fadez Et al. 2022; Trujillo Et al. 2021). Fundamental differences in brain function at the cellular level may account for the differential survival rates of Neanderthal and modern human populations.<\/li>\n<li class=\"import-Normal\">There is evidence that suggests reproduction may have posed challenges for Neanderthals. Childbirth was thought to have been at least as difficult for female Neanderthals as anatomically modern <em>Homo sapiens<\/em> (Weaver and Hublin 2009). Female Neanderthals may have become sexually mature at an older age, even older than modern humans. This delayed maturation could have kept the Neanderthal population size small. A recent study has further suggested that male Neanderthals might have had a genetic marker on the Y chromosome that could have caused incompatibility between the fetus and mother during gestation; this would have had severe consequences for birth rate and survival (Mendez Et al. 2016). Even a small but continuous decrease in fertility would have been enough to result in the extinction of Neanderthals (Degioanni Et al. 2019).<\/li>\n<li class=\"import-Normal\">As mentioned above, the end of Neanderthal existence overlaps with modern human expansion into northern Europe and Asia. There is no conclusive direct evidence to indicate that Neanderthals and modern humans lived peacefully side by side, nor that they engaged in warfare, but by studying modern societies and the tendencies of modern humans, it has been suggested that modern humans may not have warmly embraced their close but slightly odd-looking cousins when they first encountered them (Churchill Et al. 2009). Nevertheless, direct competition with modern humans for the same resources may have contributed to the Neanderthals\u2019 decline (Gilpin Et al. 2016); it may also have exposed them to new diseases, brought by modern humans (Houldcroft and Underdown 2016), which further decimated their population. Estimates of energy expenditures suggest Neanderthals had slightly higher caloric needs than modern humans (Venner 2018). When competing for similar resources, the slightly greater efficiency of modern humans might have helped them experience greater success in the face of competition\u2014at a cost to Neanderthals.<\/li>\n<\/ul>\n<p class=\"import-Normal\">It has been suggested that the Neanderthal populations were fairly small to begin with (estimated between 5,000 and 70,000 individuals; Bocquet-Appel and Degioanni 2013), one or a combination of these factors could have easily led to their demise. As more research is conducted, we will likely get a better picture of exactly what led to Neanderthal extinction.<\/p>\n<h2 class=\"import-Normal\">Denisovans<\/h2>\n<figure style=\"width: 353px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image16-4.png\" alt=\"Small fossilized finger bone sitting atop a chalk outline of hand bones.\" width=\"353\" height=\"235\" \/><figcaption class=\"wp-caption-text\">Figure 12.14: Reproduction of Denisovan finger bone. Credit: <a href=\"https:\/\/upload.wikimedia.org\/wikipedia\/commons\/6\/6f\/Denisova_Phalanx_distalis.jpg\" target=\"_blank\">Denisova Phalanx distalis<\/a> (image from Museum of Natural Sciences, Brussels, Belgium) by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Thilo_Parg\" target=\"_blank\">Thilo Parg<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">While Neanderthals represent one regionally adapted branch of the Archaic <em>Homo sapiens <\/em>family tree, recent discoveries in Siberia and the Tibetan Plateau surprised paleoanthropologists by revealing yet another population that was contemporary with Archaic <em>Homo sapiens<\/em>, Neanderthals, and modern <em>Homo sapiens<\/em>. The genetic analysis of a child\u2019s finger bone (Figure 12.14) and an adult upper third molar (Figure 12.15) from Denisova Cave in the Altai Mountains in Siberia by a team including Svante P\u00e4\u00e4bo discovered that the mitochondrial and nuclear DNA sequences reflected distinct genetic differences from all known Archaic populations. Dubbed \u201cDenisovans\u201d after the cave in which the bones were found, this population is more closely related to Neanderthals than modern humans, suggesting the two groups shared an ancestor who split from modern humans first, then the Neanderthal-Denisovan line diverged more recently (Reich Et al. 2010).<\/p>\n<figure style=\"width: 227px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image6-4-1.png\" alt=\"Molar tooth with wear, large surface area, and large roots.\" width=\"227\" height=\"341\" \/><figcaption class=\"wp-caption-text\">Figure 12.15: Reproduction of Denisovan molar. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Denisova_Molar.jpg\" target=\"_blank\">Denisova Molar<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Thilo_Parg\" target=\"_blank\">Thilo Parg<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Denisovans share up to 5% of their DNA with modern Melanesians, aboriginal Australians, and Polynesians, and 0.2% of their DNA with other modern Asian populations and Native Americans. Additional studies have suggested one (Vernot Et al. 2018) or two (Browning Et al. 2018) separate points of time when interbreeding occurred between modern humans and Denisovans.<\/p>\n<p class=\"import-Normal\">Genetic analysis reveals that Denisovans (potentially three distinct populations) had adaptations for life at high altitudes that prevented them from developing altitude sickness and hypoxia in extreme environments such as Tibet, where the average annual temperature is close to 0\u2103 and the altitude is more than a kilometre (about 4,000 feet) above sea level. Through protein analysis of a jawbone, one study (Chen Et al. 2019) has placed Denisovans in Tibet as early as 160,000 years ago. Genetic evidence of interbreeding has linked modern Tibetan populations with Denisovans 30,000 to 40,000 years ago, which implies that the unique high-altitude adaptations seen in modern Tibetans may have originated with Denisovans (Huerta-Sanchez Et al. 2014).<\/p>\n<p class=\"import-Normal\">Other research suggests tantalizing new directions regarding Denisovans. Stone tools similar to those found in Siberia have been uncovered in the Tibetan plateau suggesting a connection between the Denisovan populations in those two areas (Zhang Et al. 2018). The molar of a young girl, possibly Denisovan, has been found in Laos and shows strong similarities to specimens from China (Demeter Et al. 2022). And DNA sequencing from discoveries in the Denisova Cave have yielded a genome that has been interpreted as the first-generation offspring of a Denisovan father and Neanderthal mother (Slon Et al. 2018). While this research is not yet conclusive and is still being interpreted, exciting new possibilities are being revealed. To stay up-to-date with new discoveries, consider following organizations such as the <a href=\"https:\/\/www.facebook.com\/smithsonian.humanorigins\/\" target=\"_blank\">Smithsonian\u2019s Human Origins Program<\/a> on social media.<\/p>\n<div class=\"textbox\" style=\"background: var(--lightblue)\">\n<h2>Pleistocene Hominins in East Asia: Homo longi and Yunxian<\/h2>\n<p>New fossil discoveries, along with advanced molecular analysis, are prompting re-evaluations of the complex evolutionary dynamics of non-sapiens Homo in the middle-late Pleistocene.<\/p>\n<h3>Homo longi<\/h3>\n<p>The Harbin cranium, often referred to as Homo longi, represents one of the most remarkable Middle Pleistocene human fossils discovered in East Asia. It is currently carbon-dated at 146 ka, allowing recent scholarship to use the Harbin cranium to argue for a distinct clade of hominins that evolved independently in Eastern Asia, separate from Neanderthals and modern humans (Ni et al., 2021). This clade is argued to include Dali, Jinniushan, Hualongdong, Xiahe, and Harbin, based on phylogenetic analyses using parsimony criteria and Bayesian tip-dating, forming a third East Asian lineage and a sister group to the Homo sapiens lineage.<\/p>\n<p>The Harbin cranium exhibits a unique combination of traits, likely representing a species of Homo distinct from other Middle-to-Late Pleistocene taxa, including H. sapiens, H. Neanderthalensis, and H. Heidelbergensis\/H. Rhodesiensis. Its overall size is exceptional, setting it apart from nearly all other known fossils; however, the proportions of the cranial vault align closely with those of other large late archaic Homo species, with an estimated brain volume of approximately 1,420 mL. Despite its considerable breadth, the face is relatively low in height and exhibits a zygomaxillary shape similar to that seen in H. sapiens and H. antecessor, a feature also observed in other Middle Pleistocene Chinese fossils from Dali and Jinniushan. Additionally, the face is attached to the braincase with reduced prognathism, forming a more perpendicular angle as in modern humans, in contrast to the pronounced midfacial prognathism of Neanderthals.<\/p>\n<h3>Yunxian, China: Possible cladistic origins<\/h3>\n<p>In 2025, researchers released findings that expanded the diversity and relationships of Homo lineages in the Pleistocene, based on an analysis of fossils found in 1989\/90. Two skull fossils were found near the Hanjiang River in Hubei province, China, and were named the Yunxian 1 and Yunxian 2 crania\u2014A third cranium has recently been discovered in the same sediment layer as the two previous finds (Tu et al., 2026). The first 2 specimens were in poor condition, fragmented and distorted; however, using recently developed techniques such as high-resolution computed tomography (CT) scans, image segmentation, and digital repositioning of fragments, the researchers incorporated elements from the Yunxian 1 crania with the less damaged Yunxian 2 cranium. The Yunxian 2 cranium is a mosaic of primitive and derived traits. It retains ancient characteristics seen in earlier hominins, a thick supraorbital torus, a broad palate, a long and low vault in lateral view, and a receding frontal contour; its frontal lobe remains low and narrow, similar to H. erectus fossils. Conversely, it lacks the strongly angulated occipital bone found in H. erectus as well as the protruding occipital region or central suprainiac fossa typical of Neanderthals. The big surprise is that the zygomaxillary region is transversely flat and faces anteriorly, a feature comparable to the Hualongdong and Harbin fossils and even H. sapiens. This intermediate morphology places Yunxian 2 in a distinct position, linking archaics like H. erectus with later Asian hominins such as Harbin, Dali, and Jinniushan. Phylogenetic and morphometric analyses confirm that Yunxian 2 represents an early member of the Asian H.longi Clade. The reconstructed Yunxian 2 cranium represents a major achievement in paleoanthropology, digitally restoring a badly damaged fossil from beyond the Middle Pleistocene. In fact, recent discussion suggests an even earlier date for the Yunxian fossils at approximately 1.77 Ma (Tu et al., 2026). In their analysis, they identify the Yunxian fossils as H.erectus, and the site as Early Pleistocene. Over 500 artifacts have been recovered from the site (cores, choppers, and flakes) typical of the Early Paleolithic. Nevertheless, the mosaic morphology of the Yunxian skulls reveals characteristics within the range of both H. erectus and the Harbin skull (among others), which may position these finds as being very close to the origins and diversification of the longi clade, as well as preserving transitional features close to the sapiens clade\u00a0 (Feng et al., 2025, p.1323).<\/p>\n<p>The expanding fossil and genomic record of Archaic Homo has profoundly reshaped our understanding of Pleistocene human evolution. Discoveries, from an increasing variety of fossils found in eastern Asia, to advances in genomic research, demonstrate that multiple contemporaneous lineages once coexisted, interacted, diverged and, at times, interbred. These findings challenge earlier linear models of human ancestry and instead point to a dynamic evolutionary landscape marked by regional diversification, intermittent contact, and complex patterns of gene flow.<\/p>\n<\/div>\n<p>&nbsp;<\/p>\n<h2 class=\"import-Normal\">How Do These Fit In? <em>Homo naledi<\/em> and <em>Homo floresiensis<br \/>\n<\/em><\/h2>\n<p class=\"import-Normal\">Recently, some fossils have been unearthed that have challenged our understanding of the hominin lineage. The fossils of <em>Homo <\/em><em>naledi<\/em> and <em>Homo <\/em><em>floresiensis<\/em> are significant for several reasons but are mostly known for how they don\u2019t fit the previously held patterns of hominin evolution. While we examine information about these species, we ask you to consider the evidence presented in this chapter and others to draw your own conclusions regarding the significance and placement of these two unusual fossil species in the hominin lineage.<\/p>\n<h3 class=\"import-Normal\"><strong>Homo <\/strong><strong>naledi<\/strong><\/h3>\n<figure style=\"width: 347px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image12-5.png\" alt=\"A nearly complete skeleton surrounded by off-white bone fragments on a black table.\" width=\"347\" height=\"390\" \/><figcaption class=\"wp-caption-text\">Figure 12.16: A sample of some of the 1,550 bones found representing Homo naledi. Credit: <a href=\"https:\/\/elifesciences.org\/articles\/09560#fig1\" target=\"_blank\">Dinaledi skeletal specimens (Figure 1)<\/a> by <a href=\"https:\/\/elifesciences.org\/articles\/09560\" target=\"_blank\">Berger et al. 2015<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/legalcode\" target=\"_blank\">CC BY 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">In 2013 recreational spelunkers uncovered a collection of bones deep in a cave network in Johannesburg, South Africa. The cave system, known as Rising Star, had been well documented by other cavers; however, it appears few people had ever gone as far into the cave as these spelunkers did. Lee Berger, paleoanthropologist at University of Witwatersrand, in Johannesburg, immediately put out a call for what he termed \u201cunderground astronauts\u201d to begin recovery and excavation of the fossil materials. Unlike other excavations, Berger and most other paleoanthropologists would not be able to access the elusive site, as it was incredibly difficult to reach, and at some points there was only eight inches of space through which to navigate. The underground astronauts, all petite women anthropologists, were the only ones who were able to access this remarkable site. Armed with small excavation tools and a video camera, which streamed the footage up to the rest of the team at the surface, the team worked together and uncovered a total of 1,550 bones, representing at least 15 individuals, as seen in Figure 12.16. Later, an additional 131 bones, including an almost-complete cranium, were found in a nearby chamber of the cave, representing three more individuals (Figure 12.17). Berger called in a team of specialists to participate in what was dubbed \u201cPaleoanthropology Summer Camp.\u201d Each researcher specialized in a different portion of the hominin skeleton. With various specialists working simultaneously, more rapid analysis was possible of <em>Homo <\/em><em>naledi<\/em> than most fossil discoveries.<\/p>\n<p>&nbsp;<\/p>\n<figure style=\"width: 534px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image2-4.png\" alt=\"Photograph of four different views of the LES1 Homo naledi skull set against a black background.\" width=\"534\" height=\"599\" \/><figcaption class=\"wp-caption-text\">Figure 12.17: Several angles of the nearly complete LES1 Homo naledi skull. Credit: <a href=\"https:\/\/elifesciences.org\/articles\/24232#fig5\" target=\"_blank\">LES1 Cranium (Figure 5)<\/a> by <a href=\"https:\/\/elifesciences.org\/articles\/24232\" target=\"_blank\">Hawks et al. 2017<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/legalcode\" target=\"_blank\">CC BY 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">While access to the site, approximately 80 m from any known cave entrance or opening, was treacherous for researchers, it must have been difficult for <em>Homo <\/em><em>naledi<\/em> as well. The route included moving through a portion that is just 25 cm wide at some points, known as \u201cSuperman\u2019s Crawl.\u201d The only way to get through this section is by crawling on your stomach with one arm by your side and the other raised above your head. Past Superman\u2019s Crawl, a jagged wall known as the Dragon\u2019s Back would have been very difficult to traverse. Below that, a narrow vertical chute would have eventually led down to the area where the fossils were discovered. While geology changes over time and the cave system likely has undergone its fair share, it is not likely that these features arose after <em>Homo <\/em><em>naledi<\/em> lived (Dirks Et al. 2017). This has made scientists curious as to how the bones ended up in the bottom of the cave system in the first place. It has been suggested that <em>Homo <\/em><em>naledi<\/em> deposited the bones there, one way or another. If <em>Homo <\/em><em>naledi<\/em> did deposit the bones, either through random disposal or intentional burial, this raises questions regarding their symbolic behaviour and other cultural traits, including the use of fire, to access a very dark cave system. Another competing idea is that a few individuals may have entered the cave system to escape a predator and then got stuck. To account for the sheer number of fossils, this would have had to happen multiple times.<\/p>\n<p class=\"import-Normal\">The features of <em>Homo <\/em><em>naledi<\/em> are well-documented due to the fairly large sample, which represents individuals of all sexes and a wide range of ages. The skull shape and features are very much like other members of the genus <em>Homo<\/em>\u2014including a sagittal keel and large brow, like <em>Homo <\/em><em>erectus<\/em>, and a well-developed frontal lobe, similar to modern humans\u2014yet the brain size is significantly smaller than its counterparts, at approximately 500 cc (560 cc for males and 465 cc for females). The teeth also exhibit features of later members of the genus <em>Homo<\/em>, such as Neanderthals, including a reduction in overall tooth size. <em>Homo <\/em><em>naledi<\/em> also had unique shoulder anatomy and curved fingers, indicating similarities to tree-dwelling primates, which is very different from any other hominin yet found. Perhaps the greatest shock of all is that <em>Homo <\/em><em>naledi<\/em> has been dated to 335,000 to 236,000 years ago, placing it as a contemporary to modern <em>Homo sapiens,<\/em> despite its very primitive features. An additional specimen of a child, found in 2021, not only shares many of the unique features found in the adult specimen but will also add insight into the growth and development of individuals of this species (Brophy Et al. 2021).<\/p>\n<h3 class=\"import-Normal\"><strong>Homo <\/strong><strong>floresiensis<\/strong><\/h3>\n<p class=\"import-Normal\">In a small cave called Liang Bua, on the island of Flores, in Indonesia, a small collection of fossils were discovered beginning in 2003 (Figure 12.18). The fossil fragments represent as many as nine individuals, including a nearly complete female skeleton. The features of the skull are very similar to that of <em>Homo <\/em><em>erectus<\/em>, including the presence of a sagittal keel, an arching brow ridges and nuchal torus, and the lack of a chin (Figure 12.19). <em>Homo <\/em><em>floresiensis<\/em>, as the new species is called, had a brain size that was remarkably small at 400 cc, and recent genetic studies suggest a common ancestor with modern humans that predates <em>Homo <\/em><em>erectus<\/em>.<\/p>\n<figure style=\"width: 606px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image8-3.png\" alt=\"View from inside a large cave with people standing near a dug-out square of dirt.\" width=\"606\" height=\"403\" \/><figcaption class=\"wp-caption-text\">Figure 12.18: Liang Bua Cave on the island of Flores, in Indonesia, where a collection of Homo floresiensis specimens were discovered. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Homo_floresiensis_cave.jpg\" target=\"_blank\">Homo floresiensis cave<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/84301190@N00\" target=\"_blank\">Rosino<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\" target=\"_blank\">CC BY-SA 2.0 License<\/a>.<\/figcaption><\/figure>\n<figure style=\"width: 584px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image9-5.png\" alt=\"Photograph of a gray and off-white cast Homo floresiensis skull.\" width=\"584\" height=\"584\" \/><figcaption class=\"wp-caption-text\">Figure 12.19: Homo floresiensis had a brain that was remarkably small at 400 cc. Recent genetic studies suggest a common ancestor with modern humans that predates Homo erectus. Credit: <a href=\"https:\/\/boneclones.com\/product\/homo-floresiensis-skull-BH-033-2\" target=\"_blank\">Homo floresiensis Skull (Flores Skull LB1)<\/a> by <a href=\"https:\/\/boneclones.com\/\" target=\"_blank\">\u00a9BoneClones<\/a> is used by permission and available here under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">The complete female skeleton, who was an adult, was approximately a metre tall and would have weighed just under 30 kg, which is significantly shorter and just a few kilograms more than the average, modern, young elementary-aged child. A reconstructed comparison between an anatomically modern human and <em>Homo <\/em><em>floresiensis<\/em> can be seen in Figure 12.20. The small size of the fossil has earned the species the nickname \u201cthe Hobbit.\u201d Many questions have been asked about the stature of this species, as all of the specimens found also show evidence of diminutive stature and small brain size. Some explanations include pathology; however, this seems unlikely as all fossils found thus far demonstrate the same pattern. Another possible explanation lies in a biological phenomena seen in other animal species also found on the island, which date to a similar time period. This phenomenon, called <strong>insular dwarfing<\/strong>, is due to limited food resources on an island, which can create a selective pressure for large-bodied species to be selected for smaller size, as an island would not have been able to support their larger-bodied cousins for a long period of time. This phenomenon is the cause of other unique species known to have lived on the island at the same time, including the miniature stegodon, a dwarf elephant species.<\/p>\n<figure style=\"width: 448px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image18-4.png\" alt=\"Black-and-white drawing of a large nude woman and a much smaller man.\" width=\"448\" height=\"611\" \/><figcaption class=\"wp-caption-text\">Figure 12.20: A reconstructed comparison between an anatomically modern human and Homo floresiensis. As an adult, Homo floresiensis was approximately 1 metre tall and would have weighed under 30 kg. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-16\/\" target=\"_blank\">Anatomically modern human and Homo floresiensis (Figure 11.19)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">There is ongoing research and debate regarding <em>Homo floresiensis<\/em>\u2019 dates of existence, with some researchers concluding that they lived on Flores until perhaps as recently as 17,000 years ago, although they are more often dated to 100,000 to 60,000 years ago. Stone tools from that time period uncovered at the site are similar to other hominin stone tools found on the island of Flores. <em>Homo <\/em><em>floresiensis<\/em> would have hunted a wide range of animals, including the miniature stegodon, giant rats, and other large rodents. Other animals on the island that could have threatened them include the giant komodo dragon. An interesting note about this island chain is that ancestors of <em>Homo <\/em><em>floresiensis<\/em> would have had to traverse the open ocean in order to get there, as the nearest island is almost 10 km away, and there is little evidence to support that a land bridge connecting mainland Asia or Australia to the island would have been present. This separation from the mainland would also have limited the number of other animals, including predators and human species, that would have had access to the island. Anatomically modern <em>Homo sapiens<\/em> arrived on the island around 30,000 years ago and, if some researchers\u2019 later dates for <em>Homo <\/em><em>floresiensis<\/em> are correct, both species may have lived on Flores at the same time. The modern population living on the island of Flores today believes that their ancestors came from the Liang Bua cave; however, recent genetic studies have determined they are not related to <em>Homo <\/em><em>floresiensis<\/em> (Tucci Et al. 2018).<\/p>\n<\/div>\n<h2>Cultural Connections and Contemporary Implications<\/h2>\n<p>The Neanderthals provide an important example of how biological and cultural adaptations cannot always be understood separately. Their large brains and robust, cold-adapted bodies came with significant energetic demands, creating biological challenges that could be addressed through cultural practices. Hunting, tool use, food processing, fire, clothing, and shelter were not simply behaviours that existed alongside their biology; they allowed Neanderthals to respond to the environment and the physiological demands placed on their bodies. In this sense, culture became another means through which Neanderthals adapted to their environment.<\/p>\n<p>Their social behaviours further complicate the distinction between biological survival and cultural adaptation. Evidence of care for injured or vulnerable individuals and intentional burial suggests that their social lives extended beyond immediate individual survival. These social interactions demonstrate that adaptation was not simply a matter of being biologically suited to an environment, but also involved relationships, shared practices, and forms of social care. Although the meaning of these behaviours cannot be fully reconstructed, they challenge the simplistic image of archaic humans as primitive or solely driven by biological instincts.<\/p>\n<p>Ultimately, Neanderthals demonstrate that human adaptation is neither exclusively biological nor exclusively cultural. Their bodies were shaped by the environments in which they lived, while their cultural practices allowed them to navigate and modify those environments. Looking at Neanderthals through a biocultural perspective therefore moves us beyond the idea of the \u201ccaveman\u201d and instead recognizes them as hominins whose survival emerged through the interaction of physiology, environment, technology, and social life.<\/p>\n<h4>Discussion questions<\/h4>\n<ul>\n<li>Why might caring for the sick and injured and practicing burial rites be considered evidence of culture? What do these behaviours reveal about social life?<\/li>\n<li>Can you think of an example of the intertwining of biology and culture in humans today? What does this example reveal about the relationship between biological and cultural adaptation?<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n<div class=\"textbox\">\n<h2 class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">Hominin Species Summaries<\/span><\/h2>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<tbody>\n<tr class=\"Table3-R\" style=\"height: 0\">\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Hominin<\/strong><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Archaic <em>Homo sapiens<\/em><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 0\">\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dates<\/strong><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">600,000\u2013200,000 years ago (although some regional variation)<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 0\">\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Region(s)<\/strong><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Africa, Europe, and Asia<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 0\">\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Famous discoveries<\/strong><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Broken Hill (Zambia), Atapuerca (Spain)<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 0\">\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Brain size<\/strong><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1,200 cc average<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 0\">\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dentition<\/strong><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Slightly smaller teeth in back of mouth, larger front teeth<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 0\">\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Cranial features<\/strong><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Emerging forehead, no chin, projecting occipital region<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 0\">\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Postcranial features<\/strong><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Robust skeleton<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 0\">\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Culture<\/strong><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Varied regionally, but some continue to use Acheulean handaxe, others adopt Mousterian tool culture<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 0\">\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Other <\/strong><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Lots of regional variation in this species<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<tbody>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Species<\/strong><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><em>Homo <\/em><em>naledi<\/em><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dates<\/strong><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">335,000\u2013236,000 years ago<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Region(s)<\/strong><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">South Africa<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Famous discoveries<\/strong><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Rising Star Cave<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Brain size<\/strong><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">500 cc average<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dentition<\/strong><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Reduced tooth size<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Cranial features<\/strong><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Sagittal keel, large brow, well-developed frontal region<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Postcranial features<\/strong><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Suspensory shoulder<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Culture<\/strong><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">unknown<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Other<\/strong><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">N\/A<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<tbody>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Hominin<\/strong><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Neanderthals<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dates<\/strong><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">150,000\u201340,000 years ago<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Region(s)<\/strong><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Western Europe, Middle East, and Western Asia only<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Famous discoveries<\/strong><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Shanidar (Iraq), La Chapelle-aux-Saints (France)<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Brain size<\/strong><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1500 cc average<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dentition<\/strong><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Retromolar gap<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Cranial features<\/strong><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Large brow ridge, midfacial prognathism, large infraorbital foramina, occipital bun<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Postcranial features<\/strong><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Robust skeleton with short and stocky body, increased musculature, barrel chest<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Culture<\/strong><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Mousterian tools often constructed using the Levallois technique<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Other<\/strong><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">N\/A<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<tbody>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Species<\/strong><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><em>Homo <\/em><em>floresiensis<\/em><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dates<\/strong><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">100,000\u201360,000 years ago, perhaps as recently as 17,000 years ago<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Region(s)<\/strong><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Liang Bua, island of Flores, Indonesia<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Famous discoveries<\/strong><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">\u201cThe Hobbit\u201d<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Brain size<\/strong><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">400 cc average<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dentition<\/strong><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">unknown<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Cranial features<\/strong><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Sagittal keel, arching brow ridges, nuchal torus, no chin<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Postcranial features<\/strong><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Very short stature (approximately 3.5 ft.)<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Culture<\/strong><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Tools similar to other tools found on the island of Flores<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Other<\/strong><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">N\/A<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<tbody>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Hominin<\/strong><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Denisovans<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dates<\/strong><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">100,000\u201330,000 years ago<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Region(s)<\/strong><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Siberia<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Famous discoveries<\/strong><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Child\u2019s finger bone and adult molar<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Brain size<\/strong><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">unknown<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dentition<\/strong><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Large molars (from limited evidence)<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Cranial features<\/strong><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">unknown<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Postcranial features<\/strong><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">unknown<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Culture<\/strong><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">unknown<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Other <\/strong><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Closely related to Neanderthals (genetically)<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div class=\"textbox shaded\">\n<h2 class=\"import-Normal\">Summary<\/h2>\n<p class=\"import-Normal\">Research presented in the chapter contributes to why scientists have taken to nicknaming this time period \u201cthe muddle in the middle.\u201d We know that the Middle Pleistocene picks up from <em>Homo erectus <\/em>and ends with the appearance of anatomically modern <em>Homo sapiens<\/em>. While the start and the end are clear, it\u2019s the middle that is messy. As more research is conducted and more data is collected, rather than clarifying our understanding of the hominin lineage during this time period, it only inspires more questions, particularly about the relationships between hominins during this time period, including the oft-misunderstood Neanderthal. Research is painting a more detailed picture of Neanderthal intelligence and both biological and behavioural adaptations. At the same time, their relationship to other Middle Pleistocene hominins, including Denisovans, as well as modern humans, remains unclear.<\/p>\n<p class=\"import-Normal\"><em>Homo<\/em> <em>naledi<\/em> and <em>Homo <\/em><em>floresiensis<\/em> are clear outliers when compared to their contemporary hominin species. Each has surprised paleoanthropologists for both their archaic traits in relatively modern times and their unique combination of traits seen in archaic species and modern humans. While these finds have been exciting, they have also completely upended the assumed trajectory of the human lineage, causing scientists to re-examine assumptions about hominin evolution and what it means to be modern. Add this to the developments being made using ancient DNA, other new fossil discoveries, and other innovations in paleoanthropology, and you see that our understanding of Archaic <em>Homo sapiens<\/em> and others living during this time period is rapidly developing and changing. This is a true testament to the nature of science and the scientific method.<\/p>\n<p class=\"import-Normal\">Clearly, hominins of the Middle Pleistocene are distinct from our species today. Yet, understanding the hominins that directly preceded our species and clarifying the evolutionary relationships between us is important to better understanding our own place in nature.<\/p>\n<h2 class=\"import-Normal\">Review Questions<\/h2>\n<ul>\n<li>What physical and cultural features are unique to Archaic<em> Homo sapiens<\/em>? How are Archaic<em> Homo sapiens<\/em> different in both physical and cultural characteristics from <em>Homo <\/em><em>erectus<\/em>?<\/li>\n<li>Describe the specific changes to the brain and skull first seen in Archaic<em> Homo sapiens<\/em>. Why does the shape of the skull change so dramatically from <em>Homo <\/em><em>erectus<\/em>?<\/li>\n<li>What role did the shifting environment play in the adaptation of Archaic <em>Homo sapiens<\/em>, including Neanderthals? Discuss at least one physical feature and one cultural feature that would have assisted these groups in surviving the changing environment.<\/li>\n<li>What does the regional variation in Archaic <em>Homo sapiens<\/em> represent in terms of the broader story of our species\u2019 evolution?<\/li>\n<li>Describe the issues raised by the discoveries of <em>Homo <\/em><em>naledi<\/em> and <em>Homo <\/em><em>floresiensis<\/em> in the understanding of the story of the evolution of <em>Homo sapiens<\/em>.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<h2 class=\"__UNKNOWN__\">Key Terms<\/h2>\n<div class=\"__UNKNOWN__\">\n<p><strong>Allele<\/strong>: Each of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome.<\/p>\n<p class=\"import-Normal\"><strong>Anthropocentrism<\/strong>: A way of thinking that assumes humans are the most important species and leads to interpreting the world always through a human lens. Species-centric science and thought.<\/p>\n<p class=\"import-Normal\"><strong>Cortex<\/strong>: The outside, or rough outer covering, of a rock. Usually the cortex is removed during the process of stone tool creation.<\/p>\n<p class=\"import-Normal\"><strong>Ethnocentric<\/strong>: Applying negative judgments to other cultures based on comparison to one\u2019s own.<\/p>\n<p class=\"import-Normal\"><strong>Exogenous DNA<\/strong>: DNA that originates from sources outside of the specimen you are trying to sequence.<\/p>\n<p class=\"import-Normal\"><strong>Flexed position<\/strong>: Fetal position, in which the legs are drawn up to the middle of the body and the arms are drawn toward the body centre. Intentional burials are often found in the flexed body position.<\/p>\n<p class=\"import-Normal\"><strong>Foraminifera<\/strong>: Microscopic single-celled organisms with a shell that are common in all marine environments. The fossil record of foraminifera extends back well over 500 million years.<\/p>\n<p class=\"import-Normal\"><strong>Glaciation<\/strong>: A glacial period, or time when a large portion of the world is covered by glaciers and ice sheets.<\/p>\n<p class=\"import-Normal\"><strong>Globular<\/strong>: Round-shaped, like a globe.<\/p>\n<p class=\"import-Normal\"><strong>Grave goods<\/strong>: Items included with a body at burial. Items may signify occupation or hobbies, social status, or level of importance in the community, or they may be items believed necessary for the afterlife.<\/p>\n<p class=\"import-Normal\"><strong>Haft<\/strong>: A handle. Also used as a verb\u2014to attach a handle to an item, such as a stone tool.<\/p>\n<p class=\"import-Normal\"><strong>Infraorbital foramina<\/strong>: Small holes on the maxilla bone of the face that allows nerves and blood to reach the skin.<\/p>\n<p class=\"import-Normal\"><strong>Insular dwarfing<\/strong>: A form of dwarfism that occurs when a limited geographic region, such as an island, causes a large-bodied animal to be selected for a smaller body size.<\/p>\n<p class=\"import-Normal\"><strong>Interglacial<\/strong>: A warmer period between two glacial time periods.<\/p>\n<p class=\"import-Normal\"><strong>Levallois technique<\/strong>: A distinctive technique of stone tool manufacturing used by Archaic <em>Homo sapiens<\/em>, including Neanderthals. The technique involves the preparation of a core and striking edges off in a regular fashion around the core. Then a series of similarly sized pieces can be removed, which can then be turned into different tools.<\/p>\n<p class=\"import-Normal\"><strong>Midfacial prognathism<\/strong>: A forward projection of the nose or the middle facial region. Usually associated with Neanderthals.<\/p>\n<p class=\"import-Normal\"><strong>Mousterian tools<\/strong>: The stone tool industry of Neanderthals and their contemporaries in Africa and Western Asia. Mousterian tools are known for a diverse set of flake tools, which is different from the large bifacial tools of the Acheulean industry.<\/p>\n<p class=\"import-Normal\"><strong>Nasal aperture<\/strong>: The opening for the nose visible on a skull. Often pear- or heart-shaped.<\/p>\n<p class=\"import-Normal\"><strong>Occipital bun<\/strong>: A prominent bulge or projection on the back of the skull, specifically the occipital bone. This is a feature present only on Neanderthal skulls.<\/p>\n<p class=\"import-Normal\"><strong>Ochre<\/strong>: A natural clay pigment mixed with ferric oxide and clay and sand. Ranges in colour from brown to red to orange.<\/p>\n<p class=\"import-Normal\"><strong>Retracted face<\/strong>: A face that is flatter.<\/p>\n<p class=\"import-Normal\"><strong>Retromolar gap<\/strong>: A space behind the last molar and the end of the jaw. This is a feature present only on Neanderthals. It also occurs through cultural modification in modern humans who have had their third molars, or wisdom teeth, removed.<\/p>\n<h2 class=\"import-Normal\">For Further Exploration<\/h2>\n<p><a href=\"https:\/\/www.amnh.org\/exhibitions\/permanent-exhibitions\/anne-and-bernard-spitzer-hall-of-human-origins\">Anne and Bernard Spitzer Hall of Human Origins<\/a>\u2014American Museum of Natural History.<\/p>\n<p>\u201cDawn of Humanity,\u201d PBS documentary, 2015<\/p>\n<p><a href=\"https:\/\/www.ted.com\/talks\/svante_paeaebo_dna_clues_to_our_inner_neanderthal?language=en\" target=\"_blank\">\u201cDNA Clues to Our Inner Neanderthal,\u201d<\/a> TED Talk by Svante P\u00e4\u00e4bo, 2011.<\/p>\n<p>\u201cThe Dirt\u201d Podcast, Episode 30, <a href=\"https:\/\/thedirtpod.com\/episodes\/\/episode-30-the-human-family-tree-shrub-crabgrass-tumbleweed-part-3\" target=\"_blank\">\u201cThe Human Family Tree (Shrub? Crabgrass? Tumbleweed?), Part 3: Very Humany Indeed\u201d<\/a>.<\/p>\n<p class=\"import-Normal\"><a href=\"https:\/\/www.efossils.org\/page\/games-and-activities\" target=\"_blank\">eFossil Games and Activities<\/a><\/p>\n<p>Frank, Rebecca. 2021. \u201cThe Genus Homo.\u201d In <a href=\"https:\/\/explorations.americananthro.org\/index.php\/lab-and-activities-manual\/\" target=\"_blank\"><em>Explorations: Lab and Activity Manual, <\/em><\/a>edited by Beth Shook, Katie Nelson, Kelsie Aguilera, and Lara Braff. Arlington, VA: American Anthropological Association.<\/p>\n<p><a href=\"https:\/\/humanorigins.si.edu\/research\/asian-research-projects\/hobbits-flores-indonesia.\" target=\"_blank\">Hobbits on Flores, Indonesia<\/a> - Smithsonian Human Origins.<\/p>\n<p><a href=\"https:\/\/evolution.berkeley.edu\/evo-news\/lumping-or-splitting-in-the-fossil-record\/\" target=\"_blank\">Lumping or Splitting in the Fossil Record<\/a> - UC Berkeley Understanding Evolution.<\/p>\n<p><a href=\"https:\/\/www.eva.mpg.de\/genetics\/neandertals-and-more\/overview\/\" target=\"_blank\">Neandertals and More<\/a> - Max Planck Institute for Evolutionary Anthropology.<\/p>\n<p><a href=\"https:\/\/www.sapiens.org\/biology\/neanderthal-anatomy\/?fbclid=IwAR2Bcff1GVkTLnbCR58JAWiJzkk-Ell7zL0FUddf1HNAX6RDAZxbqh1zWoI\" target=\"_blank\">Neanderthals: Body of Evidence<\/a> - SAPIENS.<\/p>\n<p>Perash, Rose L., and Kristen A. Broehl. 2021. \u201cHominin Review: Evolutionary Trends.\u201d In <a href=\"https:\/\/explorations.americananthro.org\/index.php\/lab-and-activities-manual\/.\"><em>Explorations: Lab and Activity Manual<\/em><\/a>, edited by Beth Shook, Katie Nelson, Kelsie Aguilera, and Lara Braff. Arlington, VA: American Anthropological Association.<\/p>\n<p>Perkl, Bradley. \u201cBrain, Language, Lithics.\u201d In <a href=\"https:\/\/explorations.americananthro.org\/index.php\/lab-and-activities-manual\/.\"><em>Explorations: Lab and Activity Manual<\/em><\/a>, edited by<em>.<\/em> Beth Shook, Katie Nelson, Kelsie Aguilera, and Lara Braff. CC BY-NC. Arlington, VA: American Anthropological Association.<\/p>\n<p><a href=\"https:\/\/humanorigins.si.edu\/evidence\/human-fossils\/shanidar-3-neanderthal-skeleton\" target=\"_blank\">Shanidar 3 - Neanderthal Skeleton<\/a> - Smithsonian Human Origins.<\/p>\n<p><a href=\"https:\/\/humanorigins.si.edu\/evidence\/human-fossils\/species\" target=\"_blank\">Species<\/a> - Smithsonian Human Origins.<\/p>\n<p><a href=\"https:\/\/www.facebook.com\/smithsonian.humanorigins\/\" target=\"_blank\">Smithsonian Human Origins Program Facebook page<\/a> (@smithsonian.humanorigins).<\/p>\n<p><a href=\"https:\/\/www.smithsonianmag.com\/science-nature\/bringing-human-evolution-life-180951155\/\" target=\"_blank\">Paleoartist Brings Human Evolution to Life<\/a> - Elisabeth Dayn\u00e9s.<\/p>\n<h2 class=\"import-Normal\">References<\/h2>\n<p>Ackermann, Rebecca R., Matthew L. Arnold, et al. \u201cHybridization in Human Evolution: Insights from Other Organisms.\u201d Evolutionary Anthropology 28, no. 4 (July 2019): 189\u2013209. <a href=\"https:\/\/doi.org\/10.1002\/evan.21787\" target=\"_blank\">https:\/\/doi.org\/10.1002\/evan.21787<\/a>. <a href=\"https:\/\/pmc.ncbi.nlm.nih.gov\/articles\/PMC6980311\/\" target=\"_blank\">https:\/\/pmc.ncbi.nlm.nih.gov\/articles\/PMC6980311\/<\/a><\/p>\n<p class=\"import-Normal\">Adler, Daniel S., Timothy J. Prindiville, and Nicholas J. Conard. 2003. \u201cPatterns of Spatial Organization and Land Use During the Eemian Interglacial in the Rhineland: New Data from Wallertheim, Germany.\u201d Eurasian Prehistory 1(2): 25\u201378.<\/p>\n<p>Ahlquist, K. D., Mayra M. 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Perhaps you imagine a character from a film such as <em>The Croods<\/em>, <em>Tarzan<\/em>, and <em>Encino Man<\/em> or from the cartoon <em>The Flintstones<\/em>. Maybe you picture the tennis-playing, therapy-going hairy Neanderthals from Geico Insurance commercials. Or perhaps you imagine characters from <em>The Far Side<\/em> or <em>B.C.<\/em> comics. Whichever you picture, the character in your mind is likely stooped over with a heavy brow, tangled long locks and other body hair, and clothed in animal skins, if anything. They might be holding a club with a confused look on their face, standing at the entrance to a cave or dragging an animal carcass to a fire for their next meal (see Figure 12.1). You might have even signed up to take this course because of what you knew\u2014or expected to learn\u2014about \u201ccavemen.\u201d<\/p>\n<figure style=\"width: 163px\" class=\"wp-caption alignleft\"><img src=\"https:\/\/cdn.pixabay.com\/photo\/2013\/07\/13\/12\/36\/caveman-159964_1280.png\" alt=\"Free caveman beard man vector\" width=\"163\" height=\"317\" \/><figcaption class=\"wp-caption-text\">Figure 12.1: Cartoon illustration of a prehistoric \u201ccaveman\u201d, commonly used as a visual representation of early humans in the Stone Age. Credit: <em data-start=\"261\" data-end=\"293\">Caveman, Beard, Man, Primitive<\/em> free to use under the Pixabay <a href=\"https:\/\/pixabay.com\/service\/license-summary\/\" target=\"_blank\">Content License.<\/a><\/figcaption><\/figure>\n<p class=\"import-Normal\">These images have long been the stigma and expectation about our ancestors at the transition to modern <em>Homo sapiens<\/em>. Tracing back to works as early as Carl Linnaeus, scientists once propagated and advanced this imagery, creating a clear picture in the minds of early scholars that informed the general public, even through today, that Archaic <em>Homo sapiens<\/em>, \u201ccavemen,\u201d were somehow fundamentally different and much less intelligent than we are now. Unfortunately, this view is overly simplistic, misleading, and incorrect. Understanding what Archaic <em>Homo sapiens<\/em> were actually like requires a much more complex and nuanced picture, one that comes into sharper focus as continuing research uncovers more about the lives of our not-too-distant (and not-too-different) ancestors.<\/p>\n<p class=\"import-Normal\">The first characterizations of Archaic <em>Homo sapiens<\/em> were formed from limited fossil evidence in a time when <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1582\">ethnocentric<\/a><\/strong> and species-centric perspectives (<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1583\">anthropocentrism<\/a><\/strong>) were more widely accepted and entrenched in both society and science. Today, scientists are working from a more complete fossil record from three continents (Africa, Asia, and Europe), and genetic evidence informs their analyses and conclusions. The existence of Archaic <em>Homo sapiens<\/em> marks an exciting point in our lineage\u2014a point at which many modern traits had emerged and key refinements were on the horizon. Anatomically, humans today are not that much different from Archaic <em>Homo sapiens<\/em>.<\/p>\n<h2><\/h2>\n<h2 class=\"import-Normal\">The Changing Environment<\/h2>\n<p class=\"import-Normal\">While modern climate change is of critical concern today due to its cause (human activity) and pace (unprecedentedly rapid), the existence of global climate change itself is not a recent phenomenon. The focus of this chapter, the Middle Pleistocene (roughly between 780 kya and 125 kya), is the time period in which Archaic <em>Homo sapiens <\/em>appears in the fossil record\u2014a time that witnessed some of the most drastic climatic changes in human existence. During this time period, there were 15 major and 50 minor glacial events in Europe, alone.<\/p>\n<p class=\"import-Normal\">What exactly is <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1635\">glaciation<\/a><\/strong>? When scientists talk about glacial events, they are referring to the climate being in an ice age. This means that the ocean levels were much lower than today, because much of the earth\u2019s water was tied up in large glaciers or ice sheets. Additionally, the average temperature would have been much cooler, which would have better supported an Arctic or tundra-adapted plant-and-animal ecosystem in northern latitudes. The most interesting and relevant features of Middle Pleistocene glacial events are the sheer number of them and their repeated bouts: this era alternated between glacial periods and warmer periods, known as<strong> interglacials<\/strong>. In other words, the planet wasn\u2019t in an ice age the whole time.<\/p>\n<p class=\"import-Normal\">You can see the dramatic and increasing fluctuations in temperature, recorded through <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_906\">foraminifera<\/a><\/strong>, in Figure 12.2. The distance between highs and lows demonstrates the severity of temperature shifts. Much as the Richter scale represents more intense earthquakes with more dramatic peaks, so too does this chart, which uses dramatic peaks to demonstrate intense temperature swings.<\/p>\n<figure id=\"attachment_346-4\" aria-describedby=\"caption-attachment-346-4\" style=\"width: 1753px\" class=\"wp-caption alignnone\"><img class=\"size-full wp-image-329\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/All_palaeotemps.png\" alt=\"The graph shows changes in Earth\u2019s temperature for the last 540 My.\" width=\"1753\" height=\"565\" \/><figcaption id=\"caption-attachment-346-4\" class=\"wp-caption-text\">Figure 12.2: The Geologic Timescale and corresponding temperature shifts. Wide and rapid shifts took place during the Pleistocene (the second box from the right). More dramatic fluctuations depict greater severity of temperature shift. The Eocene, Pliocene, and Holocene epochs had more stable temperatures. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:All_palaeotemps.png\" target=\"_blank\">All paleotemps<\/a> by Glen Fergus is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Glacial periods are defined by Earth\u2019s average temperature being lower. Worldwide, temperatures are reduced, with cold areas becoming even colder. Huge portions of the landscape may have become inaccessible during glacial events due to the formation of glaciers and massive ice sheets. In Europe, the Scandinavian continental glacier covered what is today Ireland, England, Sweden, Norway, Denmark, and some of continental Europe. Plant and animal communities shifted to lower latitudes along the periphery of ice sheets. Additionally, some new land was opened during glacials. Evaporation with little runoff reduced sea levels by as much as almost 150 metres, shifting coastlines outward by in some instances as much as almost 100 kilometres. Additionally, land became exposed that connected what were previously unconnected continents such as Africa into Yemen at the Gulf of Aden.<\/p>\n<p class=\"import-Normal\">Glacial periods also affected equatorial regions and other regions that are today thought of as warmer or at least more temperate parts of the globe, including Africa. While these areas were not covered with glaciers, increased global glaciation resulted in lower sea levels and expanded coastlines. Cooler temperatures were accompanied by the drying of the climate, which caused significantly reduced rainfall, increased aridity, and the expansion of deserts. It is an interesting question to consider whether the same plants and animals that lived in these regions prior to the ice ages would be able to survive and thrive in this new climate. Plant and animal communities shifted in response to the changing climate, whenever possible.<\/p>\n<h2 class=\"import-Normal\">Surviving During the Middle Pleistocene<\/h2>\n<p class=\"import-Normal\">Rather than a single selective force, the Middle Pleistocene was marked by periods of fluctuation, not just cold periods. Interglacials interrupted glaciations, reversing trends in sea level, coastline, temperature, precipitation, and aridity, as well as glacier size and location. Interglacials are marked by increased rainfall and a higher temperature, which causes built-up ice in glaciers to melt. This leads to glacial retreat, which is the shrinking of glaciers and the movement of the glaciers back toward the poles, as we\u2019ve seen in our lifetime. During interglacials, sea levels increase, flooding some previously exposed coastlines and continental connections. In addition, plant and animal communities shift accordingly, often finding more temperate climates to the north and less arid and more humid climates in the tropics (Van Andel and Tzedakis 1996).<\/p>\n<p class=\"import-Normal\">Scientists have found that the Olorgesailie region in southern Kenya was at various times in the Middle Pleistocene a deep lake, a drought-dried lakebed with an area criss-crossed by small streams, and a grassland. While various animal species would have moved in and out of the area as the climate shifted, some animal species went extinct, and new, often related, species took up residence. The trend, scientists noted, was that animals with more specialized features went extinct and animals with more generalized features, such as animals we see today, survived in this changing climatic time period. For example, a zebra with specialized teeth for eating grass was ultimately replaced by a zebra that could eat both grass and other types of vegetation. If this small, localized example shows such a dramatic change in terms of the environment and the plant and animal biocommunities, what would have been the impact on humans?<\/p>\n<p class=\"import-Normal\">There is no way humans could have escaped the effects of Middle Pleistocene climate change, no matter what region of the world they were living in. As noted earlier, and as evidenced by what was seen in the other biotic communities, humans would have faced changing food sources as previous sources of food may have gone extinct or moved to a different latitude. Depending on where they were living, fresh water may have been limited. Durial glacials, lower sea levels would have given humans more land to live on, while the interglacials would have reduced the available land through the increase in rainfall and associated sea level rise. Dry land connections between the continents would have made movement from one continent to another by foot easier at times than today, although these passageways were not consistently available through the Middle Pleistocene due to the glacial\/interglacial cycle. Finally, as evidenced by the Olorgesailie region in Kenya, during the Middle Pleistocene animal species that were overly specialized to one particular type of environment were less likely to survive when compared to their more generalized counterparts. Evidence suggests that this same pattern may have held true for Archaic <em>Homo sapiens<\/em>, in terms of their ability to survive this dramatic period of climate change.<\/p>\n<h2 class=\"import-Normal\">Defining Characteristics of Archaic <em>Homo sapiens<\/em><\/h2>\n<p class=\"import-Normal\">Archaic <em>Homo sapiens<\/em> share our species name but are distinguished by the term \u201cArchaic\u201d as a way of recognizing both the long period of time between their appearance and ours, as well as the way in which human traits have continued to evolve over time\u2014making Archaic <em>Homo sapiens <\/em>look slightly different from us today, despite being considered the same species. Living throughout Africa, and the Middle East during the Middle Pleistocene, Archaic <em>Homo sapiens <\/em>are considered, in many ways, transitional between <em>Homo <\/em><em>erectus<\/em> and modern <em>Homo sapiens <\/em>(see Figure 12.3). Archaic<em> Homo sapiens<\/em> share the defining trait of an increased brain size of at least 1,100 cc and averaging 1,200 cc, although there are significant regional and temporal (time) variations. Because of these variations, scientists disagree on whether these fossils represent a single, variable species or multiple, closely related species (sometimes called <em>Homo antecessor<\/em>,<em> Homo bodoensis, Homo heidelbergensis<\/em>,<em> Homo georgicus<\/em>,<em> Homo neanderthalensis<\/em>, and <em>Homo rhodesiensis<\/em>).<\/p>\n<p class=\"import-Normal\">An active area of scholarship in the discipline involves reconciling the diversity of species from this time period and establishing the phylogenetic relationships between them. The term \u201cArchaic <em>Homo sapiens\u201d <\/em>can mean different things to different scholars within the discipline. The intent of this chapter is to provide an understanding of the diversity of this time period and provide data used to make interpretations from among the most likely possibilities. Although we recognize that some anthropologists split many of these fossils into separate species, until the issue is resolved at the discipline level, this chapter will rely on the widely used naming conventions that refer to many fossils from this time period as Archaic <em>Homo sapiens<\/em>. We will discuss these contemporaneous fossils as a unit<em>, <\/em>with the exception of a particularly unique population living in Europe and West Asia known as the Neanderthals, which we will examine separately.<\/p>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<caption>Figure 12.3: A comparison of Homo erectus, Archaic Homo sapiens, and anatomically modern Homo sapiens. This table compares key traits of the crania and postcrania that distinguish these three hominins. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-16\/\" target=\"_blank\">Homo erectus, Archaic Homo sapiens, and anatomically modern Homo sapiens table (Figure 11.3)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Amanda Wolcott Paskey and AnnMarie Beasley Cisneros is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/caption>\n<thead>\n<tr style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Trait<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong><em>Homo <\/em><\/strong><strong><em>erectus<\/em><\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Archaic <\/strong><strong><em>Homo sapiens <\/em><\/strong><strong>(including Neaderthals)<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Anatomically Modern <\/strong><strong><em>Homo sapiens<\/em><\/strong><\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Time<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1.8 mya\u2013200,000 ya<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">600,000\u201340,000 ya<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">315,000 ya\u2013today<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Brain size<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">900 cc<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1,200 cc (1,500 cc when including Neanderthals)<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1,400 cc<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Skull Shape<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Long and low,<\/p>\n<p class=\"import-Normal\">angular<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Intermediate<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Short and high, <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1643\">globular<\/a><\/strong><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Forehead<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Absent<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Emerging<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Present<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Nasal Region<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Projecting nasal bones (bridge of the nose), no midfacial prognathism<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Wider nasal aperture and some midfacial prognathism, particularly pronounced among Neanderthals<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Narrower nasal aperture, no midfacial prognathism<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Chin<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Absent<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Absent<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Present<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Other Facial Features<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Large brow ridge and large projecting face<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Intermediate<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Small brow ridge and<strong> retracted face<\/strong><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Other Skull Features<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Nuchal torus, sagittal keel, thick cranial bone<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Projecting occipital bone, often called occipital bun in Neanderthals; intermediate thickness of cranial bone<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Small bump on rear of skull, if anything; thin cranial bone<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dentition<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Large teeth, especially front teeth<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Slightly smaller teeth; front teeth still large;<\/p>\n<p class=\"import-Normal\">retromolar gap in Neanderthals<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Smaller teeth<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Postcranial Features<\/strong><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Robust bones of skeleton<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Robust bones of skeleton<\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">More gracile bones of skeleton<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<p class=\"import-Normal\">When comparing <em>Homo <\/em><em>erectus<\/em>, Archaic<em> Homo sapiens, <\/em>and anatomically modern <em>Homo sapiens<\/em>, one can see that Archaic<em> Homo sapiens<\/em> are intermediate in their physical form. For some features, this follows the trends first seen in <em>Homo <\/em><em>erectus<\/em> with other features having early, less developed forms of traits seen in modern <em>Homo sapiens<\/em>. For example, Archaic <em>Homo sapiens<\/em> trended toward less angular and higher skulls than <em>Homo <\/em><em>erectus<\/em><em>. <\/em>However, the archaic skulls were not as short and globular and had less developed foreheads compared to anatomically modern <em>Homo sapiens. <\/em>Archaic <em>Homo sapiens<\/em> had smaller brow ridges and a less-projecting face than <em>Homo <\/em><em>erectus<\/em> and slightly smaller teeth, although incisors and canines were often about as large as those of <em>Homo <\/em><em>erectus<\/em>. Archaic <em>Homo sapiens <\/em>also had a wider <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1638\">nasal aperture<\/a><\/strong>, or opening for the nose, and a forward-projecting midfacial region, which is later seen more fully developed among Neanderthals and is known as <strong>midfacial prognathism<\/strong>. The occipital bone often projected and the cranial bone was of intermediate thickness, somewhat reduced from <em>Homo <\/em><em>erectus<\/em> but not nearly as thin as that of anatomically modern <em>Homo sapiens. <\/em>The postcrania remained fairly robust. Identifying a set of features that is unique to Archaic<em> Homo sapiens<\/em> is a challenging task, due to both individual and geographic variation\u2014these developments were not all present to the same degree in all individuals. Neanderthals are the exception, as they had several unique traits that made them notably different from modern <em>Homo sapiens<\/em> as well as their closely related Archaic cousins.<\/p>\n<figure style=\"width: 299px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image10-4.png\" alt=\"Archaic Homo sapiens skull cast.\" width=\"299\" height=\"299\" \/><figcaption class=\"wp-caption-text\">Figure 12.4: \u201cBroken Hill Man,\u201d found at Kabwe in Zambia, shows common traits associated with archaic Homo sapiens in Africa, including a large brain, taller cranium, and Homo erectus-like features such as massive brow ridges, a large face, and thick cranial bones. Credit: <a href=\"https:\/\/boneclones.com\/product\/homo-heidelbergensis-skull-broken-hill-1-rhodesian-man-BH-004\" target=\"_blank\">Homo heidelbergensis Cranium Broken Hill 1 (Rhodesian Man)<\/a> by <a href=\"https:\/\/boneclones.com\/\" target=\"_blank\">\u00a9BoneClones<\/a> is used by permission and available here under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">The one thing that is clear about Archaic <em>Homo sapiens<\/em> is that, despite general features, there is a lot of regional variation, which is first seen in the different <em>Homo <\/em><em>erectus<\/em> specimens across Asia and Africa. While the general features of Archaic <em>Homo sapiens<\/em>, identified earlier, are present in the fossils of this time period, there are significant regional differences. The majority of this regional variation lies in the degree to which fossils have features more closely aligned with <em>Homo <\/em><em>erectus<\/em> or with anatomically modern <em>Homo sapiens<\/em>.<\/p>\n<figure style=\"width: 244px\" class=\"wp-caption alignright\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image7-5.png\" alt=\"Side view of the Dali cranium.\" width=\"244\" height=\"213\" \/><figcaption class=\"wp-caption-text\">Figure 12.5: Dali cranium, found at Dali, China, is representative of traits seen in archaic Homo sapiens in Asia, including large and robust features with heavy brow ridges like Homo erectus and a large cranial capacity intermediate between Homo erectus and anatomically modern Homo sapiens. Credit: Dali skull original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by <a href=\"https:\/\/marynelsonstudio.com\" target=\"_blank\">Mary Nelson<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p>To illustrate this point, we will examine three exemplary specimens, one from each of the three continents on which Archaic<em> Homo sapiens <\/em>lived. First, in Africa, a specimen from Broken Hill is one of several individuals found in the Kabwe lead mine in Zambia. It had a large brain (1,300 cc) and taller cranium as well as many <em>Homo erectus-<\/em>like skull features, including massive brow ridges, a large face, and thick cranial bones (Figure 12.4). Second, one partial crania from Dali, China, is representative of Archaic<em> Homo sapiens <\/em>in Asia, with large and robust features with heavy brow ridges, akin to what is seen in <em>Homo <\/em><em>erectus<\/em>, and a large cranial capacity intermediate between <em>Homo <\/em><em>erectus<\/em> and anatomically modern <em>Homo sapiens<\/em> (Figure 12.5). Third, an almost-complete skeleton was found in northern Spain at Atapuerca. Atapuerca 5 (Figure 12.6) has thick cranial bone, an enlarged cranial capacity, intermediate cranial height, and a more rounded cranium than seen previously. Additionally, Atapuerca 5 demonstrates features that foreshadow Neanderthals, including increased midfacial prognathism. After examining some of the fossils such as those from Kabwe, Dali, and Atapuerca, the transitional nature of Archaic<em> Homo sapiens <\/em>is clear: their features place them squarely between <em>Homo <\/em><em>erectus<\/em> and modern <em>Homo sapiens<\/em>.<\/p>\n<figure style=\"width: 293px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image13-4.png\" alt=\"Archaic Homo sapiens skull cast with mandible.\" width=\"293\" height=\"293\" \/><figcaption class=\"wp-caption-text\">Figure 12.6: Atapuerca 5 archaic Homo sapiens, found in northern Spain, is representative of traits seen in archaic Homo sapiens in Europe, including a thick cranial bone, an enlarged cranial capacity, intermediate cranial height, a more rounded cranium, and increased midfacial projection. Credit: <a href=\"https:\/\/boneclones.com\/product\/homo-heidelbergensis-skull-atapuerca-5-BH-022\" target=\"_blank\">Homo heidelbergensis Skull Atapuerca 5<\/a> by <a href=\"https:\/\/boneclones.com\/\" target=\"_blank\">\u00a9BoneClones<\/a> is used by permission and available here under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Due to the transitional nature of Archaic<em> Homo sapiens<\/em>, identifying the time period with which they are associated is problematic and complex. Generally, it is agreed that Archaic<em> Homo sapiens <\/em>lived between 600,000 and 200,000 years ago, with regional variation and overlap between <em>Homo <\/em><em>erectus<\/em> on the early end of the spectrum and modern <em>Homo sapiens <\/em>and Neanderthals on the latter end. The earliest-known Archaic<em> Homo sapiens <\/em>fossils tentatively date to about 600,000 years ago in Africa, to around 300,000 years ago in Asia, and to about 350,000 years ago in Europe (and potentially as early as 600,000 years ago). Determining the end point of Archaic<em> Homo sapiens <\/em>is also problematic since it largely depends upon when the next subspecies of <em>Homo sapiens <\/em>appears and the classification of highly intermediate specimens. For example, in Africa, the end of Archaic<em> Homo sapiens <\/em>is met with the appearance of modern <em>Homo sapiens<\/em>, while in Europe it is the appearance of Neanderthals that is traditionally seen as marking the transition from other Archaic<em> Homo sapiens. <\/em><\/p>\n<p class=\"import-Normal\">It is important to remember that this time period is represented by many branching relationships and assuming an evolutionary trajectory that follows a single linear path would not be correct. Even still, Archaic<em> Homo sapiens <\/em>mark an important chapter in the human lineage, connecting more ancestral forms, such as <em>Homo <\/em><em>erectus<\/em>, to modern <em>Homo sapiens<\/em>. During this period of climatic transition and fluctuation, Archaic <em>Homo sapiens<\/em> mirror the challenges of their environments. Showing increasing regional variation due to the need for local adaptation, there is no single archetype for this group; the defining characteristic seems to be variability.<\/p>\n<h2 class=\"import-Normal\">Neanderthals<\/h2>\n<p class=\"import-Normal\">One well-known population of Archaic <em>Homo sapiens <\/em>are the Neanderthals, named after the site where they were first discovered in the Neander Valley, or \u201cthal\u201d in German, located near Dusseldorf, Germany. Popularly known as the stereotypical \u201ccavemen\u201d examined at the outset of this chapter, recent research is upending long-held beliefs about this group of Archaics. Neanderthal behaviour was increasingly complex, far beyond what was exhibited by even other Archaic <em>Homo sapiens<\/em> discussed throughout this chapter. We implore you to forget the image of the iconic caveman and have an open mind when exploring the fossil evidence of the Neanderthals.<\/p>\n<p class=\"import-Normal\">It is important to understand why Neanderthals are separated from other Archaic <em>Homo sapiens<\/em>. Unlike the rest of Archaic <em>Homo sapiens<\/em>, Neanderthals are easily defined and identified in many ways. Evidence suggests the time period when Neanderthals lived was between 150,000 and 40,000 years ago. There is a clear geographic boundary of where Neanderthals lived: western Europe, the Middle East, and western Asia. No Neanderthal fossils have ever been discovered outside of this area, including Africa. This is a bit curious, as other Archaics seem to have adapted in Africa and then migrated elsewhere, but Neanderthals\u2019 regional association makes sense in light of the environment to which they were best adapted: namely, extreme cold weather. Additionally, Neanderthals have a unique and distinct cluster of physical characteristics. While a few aspects of Neanderthals are shared among some Archaic <em>Homo sapiens<\/em>, such as the types of tools, most Neanderthal anatomical and behavioural attributes are unique to them.<\/p>\n<p class=\"import-Normal\">Neanderthals lived during some of the coldest times during the last Ice Age and at far northern latitudes. This means Neanderthals were living very close to the glacial edge, rather than in a more temperate region of the globe like some of their Archaic <em>Homo sapiens<\/em> relatives. While able to survive in arctic conditions, most Neanderthal sites dating to the glacial periods were found farther away from the severe cold, in a steppe tundra-like environment, which would have been more hospitable to Neanderthals, and their food sources, both flora and fauna (Ashton 2002; Nicholson 2017; Richter 2006). Their range likely expanded and contracted along with European glacial events, moving into the Middle East during glacial events when Europe became even cooler, and when the animals they hunted would have moved for the same reason. During interglacials, when Europe warmed a bit, Neanderthals and their prey would have been able to move back into Western Europe. Clearly, the true hallmark of Neanderthals is their adaptation to an unstable environment, shifting between warm and cold, as the climate was in constant flux throughout their existence (Adler Et al. 2003; Boettger Et al. 2009).<\/p>\n<p class=\"import-Normal\">Many of the Neanderthals\u2019 defining physical features are more extreme and robust versions of traits seen in other Archaic<em> Homo sapiens<\/em>, clustered in this single population. Brain size, namely an enlargement of the cranial capacity, is one such trait. The average Neanderthal brain size is around 1,500 cc, and the range for Neanderthal brains can extend to upwards of 1,700 cc. The majority of the increase in the brain occurs in the occipital region, or the back part of the brain, resulting in a skull that has a large cranial capacity with a distinctly long and low shape that is slightly wider than previous forms at the far back of the skull. Modern humans have a brain size comparable to that of Neanderthals; however, our brain expansion occurred in the frontal region of the brain, not the back, as in Neanderthal brains. This difference is also the main reason why Neanderthals lack the vertical forehead that modern humans possess. They simply did not need an enlarged forehead, because their brain expansion occurred in the rear of their brain. Due to cranial expansion, the back of the Neanderthal skull is less angular (as compared to <em>Homo erectus<\/em>), but not as rounded as <em>Homo sapiens<\/em>, producing an elongated shape, akin to a football.<\/p>\n<p class=\"import-Normal\">Another feature that continues the trend noted in previous hominins is the enlargement of the nasal region, or the nose. Neanderthal noses are large and have a wide nasal aperture, which is the opening for the nose. While the nose is only made up of two bones, the nasals, the true size of the nose can be determined by looking at other facial features, including the nasal aperture, and the angle of the nasal and maxillary, or facial bones. In Neanderthals, these indicate a large, forward-projecting nose that appears to be pulled forward away from the rest of the face. This feature is further emphasized by the backward-sloping nature of the cheekbones, or the zygomatic arches. The unique shape and size of the Neanderthal nose is often characterized by the term <em>midfacial prognathism<\/em>\u2014a jutting out of the middle portion of the face, or nose. This is in sharp contrast to the prognathism exhibited by other hominins, who exhibited prognathism, or the jutting out, of their jaws.<\/p>\n<p class=\"import-Normal\">The teeth of the Neanderthals follow a similar pattern seen in the Archaic <em>Homo sapiens<\/em>, which is an overall reduction in size, especially as compared to the extremely large teeth seen in the genus <em>Australopithecus<\/em>. However, while the teeth continued to reduce, the jaw size did not keep pace, leaving Neanderthals with an oversized jaw for their teeth, and a gap between their final molar and the end of their jaw. This gap is called a <strong>retromolar gap<\/strong>.<\/p>\n<p class=\"import-Normal\">The projecting occipital bone present in other Archaic<em> Homo sapiens <\/em>is also more prominent in Neanderthals, extending the trend found in Archaics. Among Neanderthals, this projection of bone is easily identified by its bun shape on the back of the skull and is known as an <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1645\">occipital bun<\/a><\/strong>. This projection appears quite similar to a dinner roll in size and shape. Its purpose, if any, remains unknown.<\/p>\n<p class=\"import-Normal\">Continuing the Archaic<em> Homo sapiens <\/em>trend, Neanderthal brow ridges are prominent but somewhat smaller in size than those of <em>Homo <\/em><em>erectus<\/em> and earlier Archaic<em> Homo sapiens. <\/em>In Neanderthals, the brow ridges are also often slightly less arched than those of other Archaic<em> Homo sapiens<\/em>.<\/p>\n<p class=\"import-Normal\">In addition to extending traits present in Archaic<em> Homo sapiens, <\/em>Neanderthals possess several distinct traits. Neanderthal <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1646\">infraorbital foramina<\/a><\/strong>, the holes in the maxillae or cheek bones through which blood vessels pass, are notably enlarged compared to other hominins. The Neanderthal postcrania are also unique in that they demonstrate increased robusticity in terms of the thickness of bones and body proportions that show a barrel-shaped chest and short, stocky limbs, as well as increased musculature. These body portions are seen across the spectrum of Neanderthals\u2014in men, women, and children.<\/p>\n<p class=\"import-Normal\">Traditionally, many of the unique traits that Neanderthals possess were seen as adaptations to the extreme cold, dry environments in which they often lived and which exerted strong selective forces. For example, Bergmann\u2019s and Allen\u2019s Rules dictate that an increased body mass and short, stocky limbs are common in animals that live in cold conditions. Neanderthals were said to have matched the predictions of Bergmann\u2019s and Allen\u2019s Rules perfectly (Churchill 2006). In addition, the Neanderthal skull also exhibits adaptations to the cold. Neanderthals\u2019 large infraorbital foramina allow for larger blood vessels, increasing the volume of blood that is found closest to the skin, which helps to keep the skin warmer. Their enlarged noses resulted in longer nasal passages and mucus membranes that warmed and moistened cold air before it reached the lungs. The Neanderthals\u2019 larger nose has long been thought to have acted as a humidifier, easing physical exertion in their climate, although research on this particular trait continues to be studied and debated (Rae Et al. 2011).<\/p>\n<p class=\"import-Normal\">New research, however, seems to suggest that these unique skeletal adaptations might not have been strict adaptations to cold weather (Evteev Et al. 2017; Pearce Et al. 2013). For example, large brow ridges might have served as a way to shade the face from the sun. The increased occipital portion of the brain, some researchers state, was to support a larger visual system present in Neanderthals. This visual system would have given them increased light sensitivity, which would have been useful in higher latitudes that had dark winters. And, while recent modeling of nostril airflow on reconstructed Neanderthal specimens supports the notion that Neanderthals had extensive mucus membranes inside their noses, the data shows that modern <em>Homo sapiens<\/em> are superior to Neanderthals in our ability to use our noses as a way to warm and cool air. However, Neanderthals were able to snort air through their noses better than we can. Why is this important? When combined with the fact that Neanderthals tended to prefer a more temperate, tundra-like environment, and that other physical traits suggest that Neanderthals had huge bodies that needed massive amounts of calories to sustain them, the picture gets clearer. Massive amounts of energy would have been required to power a Neanderthal body, and anything that might have made them more calorically efficient would have been favoured. Efficient breathing, through larger noses into large lungs, meaning deeper breaths, would have been favoured. To further save energy expenditure, body sizes might have been sacrificed as well. These same types of adaptations are similar to ones seen in children today who are born in high altitudes, not cold climates. Figure 12.7 provides a summary of these unique features of the Neanderthal.<\/p>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<caption>Figure 12.7: Neanderthal distinguishing features. This table outlines key features associated with Neanderthals. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-16\/\" target=\"_blank\">Neanderthal distinguishing features table (Figure 11.6)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Amanda Wolcott Paskey and AnnMarie Beasley Cisneros is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/caption>\n<thead>\n<tr style=\"height: 21pt\">\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\" colspan=\"2\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Distinct Neanderthal Anatomical Features<\/strong><\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Brain Size<\/strong><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1,500 cc average<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Skull Shape<\/strong><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Long and low<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Brow Ridge Size<\/strong><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Large<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Nose Size<\/strong><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Large, with midfacial prognathism<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dentition<\/strong><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Reduced, but large jaw size, creating retromolar gap<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Occipital Region<\/strong><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Enlarged occipital region, occipital bun<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Other Unique Cranial Features<\/strong><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Large infraorbital foramina<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table2-R\" style=\"height: 0\">\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Postcranial Features<\/strong><\/p>\n<\/td>\n<td class=\"Table2-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Short and stocky body, increased musculature, barrel-shaped chest<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<p class=\"import-Normal\">A classic example of a Neanderthal with all of the characteristics mentioned above is the nearly complete La Ferrassie 1 Neanderthal, from France. This is a male skeleton, with a brain size of around 1640cc, an extremely large nose and infraorbital foramina, brow ridges that are marked in size, and an overall robust skeleton (Figure 12.8).<\/p>\n<p>&nbsp;<\/p>\n<figure style=\"width: 390px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image1-4.png\" alt=\"A reproduction of a complete Neanderthal skeleton.\" width=\"390\" height=\"689\" \/><figcaption class=\"wp-caption-text\">Figure 12.8: La Ferrassie 1 Neanderthal is representative of many classic Neanderthal features, including a large brain, large nose, large infraorbital foramina, large brow ridges, and robust postcrania. Credit: <a href=\"https:\/\/boneclones.com\/product\/neanderthal-skeleton-articulated-SC-019-A\" target=\"_blank\">Neanderthal Skeleton Articulated<\/a> by <a href=\"https:\/\/boneclones.com\/\" target=\"_blank\">\u00a9BoneClones<\/a> is used by permission and available here under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<h3 class=\"import-Normal\"><strong>Neanderthal Culture: Tool Making and Use<\/strong><\/h3>\n<p class=\"import-Normal\">One key Neanderthal adaptation was their cultural innovations, which are an important way that hominins adapt to their environment. As you recall, <em>Homo erectus<\/em>'s tools, Acheulean handaxes, represented an increase in complexity over Oldowan tools, allowing more efficient removal of meat and possibly calculated scavenging. In contrast, Neanderthal tools mark a significant innovation in tool-making technique and use with <strong>Mousterian tools<\/strong> (named after the Le Moustier site in southwest France). These tools were significantly smaller, thinner, and lighter than Acheulean handaxes and formed a true toolkit. The materials used for Mousterian tools were of higher quality, which allowed for both more precise toolmaking and tool reworking when the tools broke or dulled after frequent reuse. The use of higher-quality materials is also indicative of required forethought and planning to acquire them for tool manufacture. It has been suggested that the Neanderthals, unlike <em>Homo <\/em><em>erectus<\/em>, saved and reused their tools, rather than making new ones each time a tool was needed.<\/p>\n<figure style=\"width: 290px\" class=\"wp-caption alignright\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image3-4.png\" alt=\"Large flakes separated from the core.\" width=\"290\" height=\"159\" \/><figcaption class=\"wp-caption-text\">Figure 12.9: The Levallois technique is used to create Mousterian tools. The multistep process involves preparing the core in a specific way to yield flakes that can be used as tools. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Nucl%C3%A9us_Levallois_La-Parrilla.png\" target=\"_blank\">Nucl\u00e9us Levallois La-Parrilla<\/a> by Jos\u00e9-Manuel Benito \u00c1lvarez is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.5\/legalcode\" target=\"_blank\">CC BY-SA 2.5 License<\/a>..<\/figcaption><\/figure>\n<p>Mousterian tools are constructed in a very unique manner, utilizing the <strong>Levallois technique<\/strong> (Figure 12.9), named after the first finds of tools made with this technique, which were discovered in the Levallois-Perret suburb of Paris, France. The Levallois technique is a multistep process that requires preparing the core, or raw material, in a specific way that will yield flakes that are roughly uniform in dimension. The flakes are then turned into individual tools. The preparation of the core is akin to peeling a potato or carrot with a vegetable peeler\u2014when peeling vegetables, you want to remove the skin in long, regular strokes, so that you are taking off the same amount of the vegetable all the way around. In the same way, the Levallois technique requires removing all edges of the <strong>cortex<\/strong>, or outside surface of the raw material, in a circle before removing the lid. The flakes, which will eventually be turned into the individual tools, can then be removed from the core. The potential yield of tools from one core would be many, as seen in Figure 12.10, compared to all previous tool-making processes, in which one core yielded a single tool. This manufacturing process might be considered the ultimate zero-waste tool-making technique (Delpiano Et al. 2018).<\/p>\n<figure style=\"width: 589px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image19-4.png\" alt=\"Levallois core and flakes that are gray in color and various shapes and sizes.\" width=\"589\" height=\"470\" \/><figcaption class=\"wp-caption-text\">Figure 12.10: Levallois core and flakes for tool production. Using this technique, one core is used to produce many flakes, each of which can be turned into a tool. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:NHM_-_Levalloiskern.jpg\" target=\"_blank\">NHM - Levalloiskern<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Xenophon\" target=\"_blank\">Wolfgang Sauber<\/a> (user: Xenophon) is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\" target=\"_blank\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">It is suggested that Neanderthal tools were used for a variety of purposes, including cutting, butchering, woodworking or antler working, and hide working. Additionally, because the Mousterian tools were lighter than previous stone tools, Neanderthals could <strong>haft<\/strong>, or attach the tool onto a handle, as the stone would not have been too heavy (Degano Et al. 2019). Neanderthals attached small stone blades onto short wood or antler handles to make knives or other small weapons, as well as attached larger blades onto longer shafts to make spears. New research examining tar-covered stones and black lumps at several Neanderthal sites in Europe suggests that Neanderthals may have been making tar by distilling it from birch tree bark, which could have been used to glue the stone tool onto its handle. If Neanderthals were, in fact, manufacturing tar to act as glue, this would predate modern humans in Africa using tree resin or similar adhesives by nearly 100,000 years.<\/p>\n<p class=\"import-Normal\">Evidence shows that raw materials used by Neanderthals came from distances as far away as 100 km. This could indicate a variety of things regarding Neanderthal behaviour, including a limited trade network with other Neanderthal groups or simply a large area scoured by Neanderthals when collecting raw materials. While research on specific applications continues, it should be clear from this brief discussion that Neanderthal tool manufacturing was much more complex than previous tool-making efforts, requiring technical expertise, patience, and skills beyond toolmaking to carry out.<\/p>\n<h3 class=\"import-Normal\"><strong>Neanderthal Culture: Hunting and Diet<\/strong><\/h3>\n<p class=\"import-Normal\">With their more sophisticated suite of tools and robust muscular bodies, Neanderthals were better armed for hunting than previous hominins. The animal remains in Neanderthal sites show that, unlike earlier Archaic <em>Homo sapiens<\/em>, Neanderthals were very effective hunters who were able to kill their own prey, rather than relying on scavenging. Though more refined than the tools of earlier hominins, the Neanderthal spear was not the kind of weapon that would have been thrown; rather, it would have been used in a jabbing fashion (Churchill 1998; Kortlandt 2002). This may have required Neanderthals to hunt in groups rather than individually and made it necessary to approach their prey quite closely (Gaudzinski-Windheuser Et al. 2018). Remember, the animals living with Neanderthals were very large-bodied due to their adaptations to cold weather; this would have included species of deer, horses, and bovids (relatives of the cow).<\/p>\n<p class=\"import-Normal\">Isotopes from Neanderthal bones show that meat was a significant component of their diet, similar to that seen in carnivores like wolves (Bocherens Et al. 1999; Jaouen Et al. 2019; Richards Et al. 2000). In addition to large prey, their diet included ibex, seals, rabbits, and pigeons. Though red meat was a critical component of the Neanderthal diet, evidence shows that at times they also ate limpets, mussels, and pine nuts. Tartar examined from Neanderthal teeth in Iraq and Belgium reveal that they also ate plant material including wheat, barley, date palms, and tubers, first cooking them to make them palatable (Henry Et al. 2010). While Neanderthals\u2019 diet varied according to the specific environment in which they lived, meat comprised up to 80% of their diet (Wi\u1e9ein Et al. 2015).<\/p>\n<h3 class=\"import-Normal\"><strong>Neanderthal Culture: Caring for the Injured and Sick<\/strong><\/h3>\n<p class=\"import-Normal\">While the close-range style of hunting used by Neanderthals was effective, it also had some major consequences. Many Neanderthal skeletons have been found with significant injuries, which could have caused paralysis or severely limited their mobility. Many of the injuries are to the head, neck, or upper body. Thomas Berger and Erik Trinkaus (1995) conducted a statistical comparative analysis of Neanderthal injuries compared to those recorded in modern-day workers\u2019 compensation reports and found that the closest match was between Neanderthal injuries and those of rodeo workers. Rodeo professionals have a high rate of head and neck injuries that are similar to the Neanderthals\u2019 injuries. What do Neanderthals and rodeo workers have in common? They were both getting very close to large, strong animals, and at times their encounters went awry.<\/p>\n<p class=\"import-Normal\">The extensive injuries sustained by Neanderthals are evident in many fossil remains. Shanidar 1 (Figure 12.11), an adult male found at the Shanidar site in northern Iraq and dating to 45,000 ya, has a lifetime of injuries recorded in his bones (Stewart 1977). Shanidar 1 sustained\u2014and healed from\u2014an injury to the face that would have likely caused blindness. His lower right arm was missing and the right humerus shows severe atrophy, likely due to disuse. This pattern has been interpreted to indicate a substantial injury that required or otherwise resulted in amputation or wasting away of the lower arm. Additionally, Shanidar 1 suffered from bony growths in the inner ear that would have significantly impaired his hearing and severe arthritis in the feet. He also exhibited extensive anterior tooth wear, matching the pattern of wear found among modern populations who use their teeth as a tool. Rather than an anomaly, the type of injuries evident in Shanidar 1 are similar to those found in many other Neanderthal fossils, revealing injuries likely sustained from hunting large mammals as well as demonstrating a long life of physical activity.<\/p>\n<p>&nbsp;<\/p>\n<p><img class=\"aligncenter\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image11-4.png\" alt=\"Neaderthal skull.\" width=\"329\" height=\"329\" \/><\/p>\n<figure style=\"width: 330px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image5-4.png\" alt=\"Neaderthal right and left humerus. The right humerus is withered looking.\" width=\"330\" height=\"330\" \/><figcaption class=\"wp-caption-text\">Figure 12.11a-b: a. The Shanidar 1 skull shows an injury to the face that would likely have caused blindness. b. The Shanidar 1 right humerus (on the left side of the image) shows severe atrophy, likely due to disuse. Credit: a. <a href=\"https:\/\/boneclones.com\/product\/shanidar-1-skull-BH-050\" target=\"_blank\">Homo neanderthalensis Shanidar 1 Skull<\/a> by <a href=\"https:\/\/boneclones.com\/\" target=\"_blank\">\u00a9BoneClones<\/a> is used by permission and available here under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>. b. <a href=\"https:\/\/humanorigins.si.edu\/evidence\/human-fossils\/fossils\/shanidar-1\" target=\"_blank\">Shanidar 1<\/a> by Chip Clark, <a href=\"https:\/\/www.si.edu\/\" target=\"_blank\">Smithsonian Institution<\/a> [exhibit: <a href=\"https:\/\/humanorigins.si.edu\/research\" target=\"_blank\">Human Evolution <\/a>Evidence, Human Fossils, Species, Homo neanderthalensis] <a href=\"https:\/\/www.si.edu\/termsofuse\" target=\"_blank\">is used for educational and non-commercial purposes as outlined by the Smithsonian.<\/a><\/figcaption><\/figure>\n<p class=\"import-Normal\">The pattern of injuries is as significant as the fact that Shanidar 1 and other injured Neanderthals show evidence of having <em>survived<\/em> their severe injuries. One of the earliest-known Neanderthal discoveries\u2014the one on whom misinformed analysis shaped the stereotype of the species for nearly a century\u2014is the La Chapelle-aux-Saints Neanderthal (Trinkaus 1985). The La Chapelle Neanderthal had a damaged eye orbit that likely caused blindness and suffered arthritis of the spine (Dawson and Trinkaus 1997). He had also lost most of his teeth, many of which he had lived without for so long that the mandibular and maxillary bones were partially reabsorbed due to lack of use. The La Chapelle Neanderthal was also thought to be at least in his mid-forties at death, an old age for the rough life of the Late Pleistocene\u2014giving rise to his nickname, \u201cthe Old Man.\u201d To have survived so long with so many injuries that obviously precluded successful large game hunting, he must have been taken care of by others. Such caretaking behaviour is also evident in the survival of other seriously injured Neanderthals, such as Shanidar 1. Long thought to be a hallmark modern human characteristic, taking care of the injured and elderly, for example preparing or pre-chewing food for those without teeth, indicates strong social ties among Neanderthals.<\/p>\n<h3 class=\"import-Normal\"><strong>Neanderthal Culture: Ritual Life<\/strong><\/h3>\n<p class=\"import-Normal\">Such care practices may have been expressed upon death as well. Nearly complete Neanderthal skeletons are not uncommon in the fossil record, and most are well preserved within apparently deliberate burials that involve deep graves and bodies found in specific, often fetal or <strong>flexed positions<\/strong> (Harrold 1980)<strong>.<\/strong> Discoveries of pollen in a grave at the Shanidar site in the 1960s led scientists to think that perhaps Neanderthals had placed flowering plants in the grave, an indication of ritual ceremony or spirituality so common in modern humans. But more recent investigations have raised some doubt about this conclusion (Pomeroy Et al. 2020). The pollen may have been brought in by burrowing rodents. Claims of <strong>grave goods<\/strong> or other ornamentation in burials are similarly debated, although possible.<\/p>\n<p class=\"import-Normal\">Some tantalizing evidence for symbolism, and debatably, ritual, is the frequent occurrence of natural pigments, such as <strong>ochre<\/strong> (red) and manganese dioxide (black) in Neanderthal sites that could have been used for art. However, the actual uses of pigments are unclear, as there is very little evidence of art or paintings in Mousterian sites. One exception may be the recent discovery in Spain of a perforated shell that appears to be painted with an orange pigment, which may be evidence of Neanderthal art and jewelry. However, many pigments also have properties that make them good emulsifiers in adhesive (like for attaching a stone tool to a wooden handle) or useful in tanning hides. So the presence of pigment may or may not be associated with symbolic thought; however, it definitely does show a technological sophistication beyond that of earlier Archaic hominins.<\/p>\n<div class=\"textbox shaded\" style=\"background: var(--lightblue)\">\n<h2>Dig Deeper: Evidence of Endocannibalism Among the Neanderthals<\/h2>\n<p>Krapina, a Neanderthal site in Croatia, has recently sparked new archeological discourse as many investigations upon fossilized remains show evidence of post-mortem modifications and manipulations of limbs and bones through the use of tools (Rougier Et al., 2016). These findings provide compelling evidence of Neanderthals engaging in cannibalism as part of their post-mortem practices. Additionally, these uncovered remains were found to have died of natural causes as opposed to being killed, showing that even the earliest humans may have had some sort of morality or ethics surrounding the cannibalizing of their kin, meaning they were aware of death in a social context as opposed to merely a physical one.<\/p>\n<p>While the original evidence in Krapina was uncovered in 1901, Croatian geologist and paleontologist Dragutin Gorjanovi\u0107-Kramberger\u2019s discovery of fragmented and burned human bones (Ullrich, 2005) was not yet confirmed to be linked to endocannibalism until much later. Whereas the discovery of burned bones does not mean they were being prepared for consummation, due to its context among other findings, this information supports the hypothesis that early hominids conducted post-mortem rituals and practices with their dead. Building on Gorjanovi\u0107-Kramberger\u2019s research, Herbert Ullrich wrote in <em>Anthropologie<\/em> (2005) that broken bones\u2014resulting from post-mortem bodily manipulations\u2014were \u201cdefleshed in preparation for secondary burial\u201d (2005, 251) and intentionally left outside rock shelters, while selectively chosen bones were seemingly brought inside for use in mortuary practices.<\/p>\n<p>For nearly 150 years, since the first Neanderthal skeletal remains were discovered, anthropologists and researchers have continued to debate the cognitive, social, and physical abilities of this species. In 2016, Rougier and colleagues wrote in <em>Scientific Reports<\/em>, furthering the research, presenting 99 new Neanderthal remains found in Goyet, Belgium. Among these remains, similar evidence of human-induced alterations was identified, including signs of butchering, consumption, and the use of bones to modify stone tools (Rougier Et al., 2016). This discovery provides significant support for the presence of cannibalistic behaviour among Northern European Neanderthals, contributing to the growing body of evidence that Neanderthals engaged with death in ways that reflect social awareness, ritual behaviour, and complex cultural practices.<\/p>\n<p><strong>Contemporary Cases of Prion Disease Related to Endocannibalism<\/strong><\/p>\n<p>The evidence of endocannibalism does not end with early hominids; with Australian medical anthropologists recording thousands of cannibalism-related prion disease occurrences present in populations up until 2009 (Radford &amp; Scragg, 2013). Following a mysterious epidemic of a new form of spongiform encephalopathy\u2013a \u201cprogressive degenerative disease of the central nervous system\u201d (2013, p.29)\u2013anthropological research regarding the the cultural mortuary rites within the Okapa region of Papua New Guinea have linked the newfound disease \u2018Kuru\u2019 to post-mortem consumption of human remains (Radford &amp; Scragg, 2013; Collinge Et al., 2006).<\/p>\n<p>Local oral histories collected during the first investigations by these researchers in the 1950s traced the earliest cases back to the 1920s, with detailed case histories. Epidemiological data revealed a strong correlation between the spread of Kuru and participation in mortuary feasts, in which the deceased were ritually consumed as part of funerary rites (2006, p. 2070). From 1957 to 2004, over 2,700 cases were reported, with mortality peaking at over 200 deaths annually in the late 1950s (2006, p.2070); however, following the cessation of cannibalism in the easly 1960s due to governmental efforts, natural transmission of the disease has stopped, dropping the death toll dramatically, with the \u201clast three single cases reported in 2005, 2007, and 2009\u201d (Radford &amp; Scragg, p.48).<\/p>\n<\/div>\n<h3 class=\"import-Normal\"><strong>The Lasting Gift of Neanderthals: Tantalizing New Directions for Resear<\/strong><strong>ch<\/strong><\/h3>\n<p class=\"import-Normal\">Examining the more recent time period in which Neanderthals lived and the extensive excavations completed across Europe allows for a much more complete archaeological record from this time period. Additionally, the increased cultural complexity such as complex tools and ritual behaviours expressed by Neanderthals left a more detailed record than previous hominins. Intentional burials enhanced preservation of the dead and potentially associated ritual behaviours. Such evidence allows for a more complete and nuanced picture of this species.<\/p>\n<figure style=\"width: 424px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image15-5.png\" alt=\"Museum exhibition of life-sized Neanderthal figure.\" width=\"424\" height=\"469\" \/><figcaption class=\"wp-caption-text\">Figure 12.12: Artistic reconstruction of Neanderthal at The Natural History Museum in Vienna, Austria. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Homo_neanderthalensis,_The_Natural_History_Museum_Vienna,_20210730_1223_1272.jpg\" target=\"_blank\">Homo neanderthalensis, The Natural History Museum Vienna, 20210730 1223 1272<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Jakubhal\" target=\"_blank\">Jakub Ha\u0142un<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/legalcode\" target=\"_blank\">CC BY 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Additional analyses are possible on many Neanderthal finds, due to increased preservation of bone, the amount of specimens that have been uncovered, and the recency in which Neanderthals lived. We should be cautious, however, to consider the potential bias of many Neanderthal sites. Overwhelmingly, Neanderthal skeletons are found complete, with injuries or evidence of disease in caves. Does this mean all Neanderthals lived a tough, disease-wrought life? Probably not. It does, however, indicate that the sick were cared for by others, and that they lived in environments that preserved their bodies incredibly well. These additional studies include the examination of dental calculus and even DNA analysis. While limited, samples of Neanderthal DNA have been successfully extracted and analysed. Research thus far has identified specific genetic markers that show some Neanderthals were light-skinned and probably red-haired with light eyes. Genetic analyses, different from the typical hominin reconstruction done with earlier species, allow scientists to further investigate soft tissue markers of Neanderthals and other more recent hominin species. These studies offer striking conclusions regarding Neanderthal traits, their physical appearance, and their culture, as reflected in these artists\u2019 reconstructions (Figure 12.12).<\/p>\n<figure style=\"width: 258px\" class=\"wp-caption alignright\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image17-4.png\" alt=\"Photograph of Dr. Svante P\u00e4\u00e4bo in a blue suit and red tie.\" width=\"258\" height=\"368\" \/><figcaption class=\"wp-caption-text\">Figure 12.13: Nobel Prize winner (2022) and pioneer in paleogenomic research, Dr. Svante P\u00e4\u00e4bo. Credit: <a href=\"https:\/\/upload.wikimedia.org\/wikipedia\/commons\/2\/26\/Professor_Svante_Paabo_ForMemRS_%28cropped%29.jpg\" target=\"_blank\">Professor Svante Paabo ForMemRS (cropped)<\/a> by Duncan.Hull is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Dr. Svante P\u00e4\u00e4bo (Figure 12.13), of the Max Planck Institute for Evolutionary Anthropology, has been at the forefront of much of this new research, largely in the form of genomic studies (The Nobel Prize 2022). Awarded the Nobel Prize for Physiology or Medicine in 2022, P\u00e4\u00e4bo is known primarily for his work with ancient DNA. He has successfully sequenced mitochondrial DNA (mtDNA) as well as the entire Neanderthal genome from nuclear DNA. His genomic work has led to the realization that Denisovans are genetically distinct from Neanderthals, as well as the recent identification of a Neanderthal father and teenage daughter, which he discovered by looking for unique DNA markers in the fossil record. Additionally, P\u00e4\u00e4bo\u2019s genomic work has provided researchers with additional lines of evidence regarding the connections between hominin fossils (such as Neanderthals) and modern people, their time of divergence, and current genetic overlap. The work of P\u00e4\u00e4bo has even formalized a new field of study within anthropology\u2014paleogenomics. To stay up to date with Dr. Svante P\u00e4\u00e4bo\u2019s work, be sure to follow his <a href=\"https:\/\/www.eva.mpg.de\/genetics\/neandertals-and-more\/overview\/\" target=\"_blank\">lab\u2019s website<\/a>.<\/p>\n<h3 class=\"import-Normal\"><strong>Neanderthal Culture: Communicating through Speech<\/strong><\/h3>\n<p class=\"import-Normal\">To successfully live in groups and to foster cultural innovations, Neanderthals would have required at least a basic form of communication in order to function, possibly using a speech-based communication system. The challenge with this line of research is that speech, of course, is not preserved, so indirect evidence must be used to support this conclusion. It is thought that Neanderthals would have possessed some basic speech, as evidenced from a variety of sources, including throat anatomy and genetic evidence (Lieberman 1971). There is only one bone in the human body that could demonstrate if a hominin was able to speak, or produce clear vocalizations like modern humans, and that is the hyoid, a U-shaped bone that is found in the throat and is associated with the ability to precisely control the vocal cords. Very few hyoid bones have been found in the archaeological record; however, a few have been uncovered in Neanderthal burials. The shape of the Neanderthal hyoid is nearly identical to that of modern humans, pointing to the likelihood that they had the same vocal capabilities as modern humans. In addition, geneticists have uncovered a mutation present in both modern humans and Neanderthals\u2014the FOXP2 gene\u2014that is possibly linked to the ability to speak. However, other scientists argue that we cannot make sweeping conclusions that the FOXP2 gene accounts for speech due to small sample size. Finally, scientists have also pointed to the increasingly complex cultural behaviour of Neanderthals as a sign that symbolic communication, likely through speech, would have been the only way to pass down the skills needed to make, for example, a Levallois blade or to position a body for intentional burial.<\/p>\n<h3 class=\"import-Normal\"><strong>Neanderthal Intelligence<\/strong><\/h3>\n<p class=\"import-Normal\">One of the enduring questions about Neanderthals centres on their intelligence, specifically in comparison to modern humans. Brain volume indicates that Neanderthals certainly had a large brain, but it continues to be debated if Neanderthals were of equal intelligence to modern humans. Remember, creatures with larger body sizes tend to have larger brains; however, scaling of the brain is not always associated with greater intelligence (Alex 2018). Brain volume (cranial capacity), cultural complexity, tool use, and compassion toward their kind all point to an increase in intellect among Neanderthals when compared to previous hominins.<\/p>\n<p class=\"import-Normal\">Yet, new research is suggesting additional differences between Neanderthal brains and our own. For example, Euluned Pearce and colleagues (2013), from the University of Oxford, noted the frontal lobes of Neanderthals and modern humans are almost identical. However, Neanderthals had a larger visual cortex\u2014the portion of the brain involved in processing visual information. This would have left Neanderthals with less brain tissue for other functions, including those that would have aided them in dealing with large social groupings, one of the differences that has been suggested to exist between Neanderthals and modern humans. Other differences were found when geneticist John Blangero, from the Texas Biomedical Research Institute, compared data from the Neanderthal genome against data from modern study participants. Blangero and his colleagues (Blangero Et al. 2014) discovered that some Neanderthal brain components were very different, and smaller, than those in the modern sample. Differences were found in areas associated with the processing of information and controlling emotion and motivation, as well as overall brain connectivity. In short, as Blangero stated, \u201cNeanderthals were certainly cognitively adept,\u201d although their specific abilities may have differed from modern humans\u2019 in key areas (qtd. in Wong 2015). This point has been echoed in other recent genetic studies comparing Neanderthal and anatomically modern human brains (el-Showk 2019).<\/p>\n<p class=\"import-Normal\">Finally, scientists are fairly certain that Neanderthal brain development after birth was not the same as that of modern humans. After birth, anatomically modern <em>Homo sapiens <\/em>babies go through a critical period of brain expansion and cognitive development. It appears that Neanderthal babies\u2019 brains and bodies did not follow the same developmental pattern (Smith Et al. 2010; Zollikofer and Ponce de Le\u00f3n 2013). Modern humans enjoy an extended period of childhood, which allows children to engage in imaginative play and develop creativity that fosters cognitive skills. Neanderthals had a more limited childhood, with less development of the creative mind that may have affected their species\u2019 success (Nowell 2016).<\/p>\n<p class=\"import-Normal\">The exact nature of Neanderthal intelligence remains under investigation, however. Some studies disagree with the idea that Neanderthal intelligence had limitations compared to our own, noting the extensive evidence of Neanderthals having limb asymmetry. Their tools also have wear marks indicating that they were hand-dominant. This is further supported by marks on Neanderthal teeth that demonstrate hand dominance. The Neanderthal \u201cstuff-and-cut method\u201d of eating, noted by David Frayer and colleagues (Frayer Et al. 2012), would have seen Neanderthals hold a piece of meat in their teeth, while pulling it taut with one hand, and then using the other hand, their dominant one, to cut the meat off of the larger slab being held in their teeth. When looking at 17 Neanderthals and their tooth wear, only two do not show markings associated with a right-hand dominant individual eating in this manner. Further, it has been established that favouring the right hand is a key marker between modern humans and chimpanzees, and that handedness also relates to language development, in the form of bilateral brain development. That Neanderthals likely were hand-dominant suggests they had an indicator of bilateral brain development and a precondition for human speech.<\/p>\n<h2 class=\"import-Normal\">The Middle Stone Age: Neanderthal Contemporaries in Africa<\/h2>\n<p class=\"import-Normal\">While Neanderthals made their home on and adapted to the European and Asian continents, evidence of fossil humans in Africa show they were also adapting to their local environments. These populations in Africa exhibit many more similarities to modern humans than Neanderthals, as well as overall evolutionary success. While the African fossil sample size is smaller and more fragmentary than the number of Neanderthal specimens across Europe and Asia, the African sample is interesting in that it represents a longer time period and larger geographical area. This group of fossils\u2014often represented by the name \u201cMiddle Stone Age,\u201d or MSA\u2014dates to between 300,000 and 30,000 years ago across the entire continent of Africa. As with Archaic <em>Homo sapiens<\/em>, there is much variability seen in this African set of fossils. There are also a few key consistent elements: none of them exhibit Neanderthal skeletal features; instead, they demonstrate features that are increasingly consistent with anatomically modern <em>Homo sapiens<\/em>.<\/p>\n<p class=\"import-Normal\">Similarities to Neanderthals and MSA contemporaries in Africa are seen, however, in their behavioural adaptations, including stone tools and other cultural elements. The tools associated with the specimens living in Africa during this time period are, like their physical features, varied. In some parts of Africa, namely Northern Africa, stone tools from this time so closely resemble Neanderthal tools that they are classified as Mousterian. In sub-Saharan Africa, the stone tools associated with these specimens are labeled as MSA. Some scholars argue that these could also be a type of Mousterian tools, but they are still typically subdivided based on geographical location.<\/p>\n<p class=\"import-Normal\">Recall that Mousterian tools were much more advanced than their Acheulean predecessors in terms of how the stone tools were manufactured, the quality of the stones used, and the ultimate use of the tools that were made. In addition, recent evidence suggests that MSA tools may also have been heat treated\u2014to improve the quality of the stone tool produced (Stolarczyk and Schmidt 2018). Evidence for heat treating is seen not only through advanced analysis of the tool itself but also through the residue of fires from this time period. Fire residues show a shift over time from small, short fires fuelled by grasses (probably intended for cooking) to larger, more intensive fires that required the exploitation of dry wood, exactly the type of fire that would have been needed for heat treating stone tools (Esteban Et al. 2018).<\/p>\n<p class=\"import-Normal\">Other cultural elements seen with MSA specimens include the use of marine (sea-based) resources for their diet (Parkington 2003), manufacture of bone tools, use of adhesive and compound tools (e.g., hafted tools), shell bead production, engraving, use of pigments (such as ochre), and other more advanced tool-making technology (e.g., microlithics). While many of these cultural elements are also seen to a limited extent among Neanderthals, developments at MSA sites appear more complex. This MSA cultural expansion may have been a response to climate change or an increased use of language, complex communication, and\/or symbolic thought. Others have suggested that the MSA cultural expansion was due to the increase of marine resources in their diet, which included more fatty acids that may have aided their cognitive development. Still others have suggested that the increased cultural complexity was due to increased interaction among groups, which spurred competition to innovate. Recent studies suggest that perhaps the best explanation for the marked cultural complexity of MSA cultural artifacts is best explained by the simple fact that they lived in diverse habitats (Kandel Et al. 2015). This would have necessitated a unique set of cultural adaptations for each habitat type (for example, specialized marine tools would have been needed along coastal sites but not at inland locations). Simply put, the most useful adaptation of MSA was their flexibility of behaviour and adaptability to their local environment. As noted previously in this chapter, flexibility of behaviour and physical traits, rather than specialization, seems to be a feature that was favoured in hominin evolution at this time.<\/p>\n<h2 class=\"import-Normal\">Where Did They Go? The End of Neanderthals<\/h2>\n<p class=\"import-Normal\">While MSA specimens were increasingly successful and ultimately transitioned into modern <em>Homo sapiens<\/em>, Neanderthals disappeared from the fossil record by around 40,000 years ago. What happened to them? We know, based on genetics, that modern humans come largely from the modern people who occupied Africa around 300,000 to 100,000 years ago, at the same time that Neanderthals were living in northern Europe and Asia. As you will learn in Chapter 13, modern humans expanded out of Africa around 150,000 years ago, rapidly entering areas of Europe and Asia inhabited by Neanderthals and other Archaic hominins. Despite intense interest and speculation in fictional works about possible interactions between these two groups, there is very little direct evidence of either peaceful coexistence or aggressive encounters. It is clear, though, that these two closely related hominins shared Europe for thousands of years, and recent DNA evidence suggests that they occasionally interbred (Fu Et al. 2015). Geneticists have found traces of Neanderthal DNA (as much as 1% to 4%) in modern humans of European and Asian descent not present in modern humans from sub-Saharan Africa. This is indicative of limited regional interbreeding with Neanderthals.<\/p>\n<p class=\"import-Normal\">While some interbreeding likely occurred, as a whole, Neanderthals did not survive. What is the cause for their extinction? This question has fascinated many researchers and several theories have been suggested, including:<\/p>\n<ul>\n<li class=\"import-Normal\">At the time that Neanderthals were disappearing from the fossil record, the climate went through both cooling and warming periods\u2014each of which posed challenges for Neanderthal survival (Defleur and Desclaux 2019; Staubwasser Et al. 2018). It has been argued that as temperatures warmed, large-bodied animals, well adapted to cold weather, moved farther north to find colder environments or faced extinction. A shifting resource base could have been problematic for continued Neanderthal existence, especially as additional humans, in the form of modern <em>Homo sapiens<\/em>, began to appear in Europe and compete for a smaller pool of available resources.<\/li>\n<li class=\"import-Normal\">It has been suggested that the eruption of a European volcano 40,000 years ago could have put a strain on available plant resources (Golovanova Et al. 2010). The eruption would have greatly affected local microclimates, reducing the overall temperature enough to alter the growing season.<\/li>\n<li class=\"import-Normal\">Possible differences in cognitive development may have limited Neanderthals in terms of their creative problem solving. As much as they were biologically specialized for their environment, the nature of their intelligence might not have offered them the creative problem-solving skills to innovate ways to adapt their culture when faced with a changing environment (Pearce Et al. 2013).<\/li>\n<li class=\"import-Normal\">CRISPR gene-editing technology has been used in studies to evaluate potential differences between human and Neanderthal brains, based on differences in the genetic code. Potential differences include a Neanderthal propensity for mutations related to brain development that could account for more rapid brain development, maturation, synapse misfires, and less-orderly neural processes (Mora-Berm\u00fadez Et al. 2022; Trujillo Et al. 2021). Fundamental differences in brain function at the cellular level may account for the differential survival rates of Neanderthal and modern human populations.<\/li>\n<li class=\"import-Normal\">There is evidence that suggests reproduction may have posed challenges for Neanderthals. Childbirth was thought to have been at least as difficult for female Neanderthals as anatomically modern <em>Homo sapiens<\/em> (Weaver and Hublin 2009). Female Neanderthals may have become sexually mature at an older age, even older than modern humans. This delayed maturation could have kept the Neanderthal population size small. A recent study has further suggested that male Neanderthals might have had a genetic marker on the Y chromosome that could have caused incompatibility between the fetus and mother during gestation; this would have had severe consequences for birth rate and survival (Mendez Et al. 2016). Even a small but continuous decrease in fertility would have been enough to result in the extinction of Neanderthals (Degioanni Et al. 2019).<\/li>\n<li class=\"import-Normal\">As mentioned above, the end of Neanderthal existence overlaps with modern human expansion into northern Europe and Asia. There is no conclusive direct evidence to indicate that Neanderthals and modern humans lived peacefully side by side, nor that they engaged in warfare, but by studying modern societies and the tendencies of modern humans, it has been suggested that modern humans may not have warmly embraced their close but slightly odd-looking cousins when they first encountered them (Churchill Et al. 2009). Nevertheless, direct competition with modern humans for the same resources may have contributed to the Neanderthals\u2019 decline (Gilpin Et al. 2016); it may also have exposed them to new diseases, brought by modern humans (Houldcroft and Underdown 2016), which further decimated their population. Estimates of energy expenditures suggest Neanderthals had slightly higher caloric needs than modern humans (Venner 2018). When competing for similar resources, the slightly greater efficiency of modern humans might have helped them experience greater success in the face of competition\u2014at a cost to Neanderthals.<\/li>\n<\/ul>\n<p class=\"import-Normal\">It has been suggested that the Neanderthal populations were fairly small to begin with (estimated between 5,000 and 70,000 individuals; Bocquet-Appel and Degioanni 2013), one or a combination of these factors could have easily led to their demise. As more research is conducted, we will likely get a better picture of exactly what led to Neanderthal extinction.<\/p>\n<h2 class=\"import-Normal\">Denisovans<\/h2>\n<figure style=\"width: 353px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image16-4.png\" alt=\"Small fossilized finger bone sitting atop a chalk outline of hand bones.\" width=\"353\" height=\"235\" \/><figcaption class=\"wp-caption-text\">Figure 12.14: Reproduction of Denisovan finger bone. Credit: <a href=\"https:\/\/upload.wikimedia.org\/wikipedia\/commons\/6\/6f\/Denisova_Phalanx_distalis.jpg\" target=\"_blank\">Denisova Phalanx distalis<\/a> (image from Museum of Natural Sciences, Brussels, Belgium) by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Thilo_Parg\" target=\"_blank\">Thilo Parg<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">While Neanderthals represent one regionally adapted branch of the Archaic <em>Homo sapiens <\/em>family tree, recent discoveries in Siberia and the Tibetan Plateau surprised paleoanthropologists by revealing yet another population that was contemporary with Archaic <em>Homo sapiens<\/em>, Neanderthals, and modern <em>Homo sapiens<\/em>. The genetic analysis of a child\u2019s finger bone (Figure 12.14) and an adult upper third molar (Figure 12.15) from Denisova Cave in the Altai Mountains in Siberia by a team including Svante P\u00e4\u00e4bo discovered that the mitochondrial and nuclear DNA sequences reflected distinct genetic differences from all known Archaic populations. Dubbed \u201cDenisovans\u201d after the cave in which the bones were found, this population is more closely related to Neanderthals than modern humans, suggesting the two groups shared an ancestor who split from modern humans first, then the Neanderthal-Denisovan line diverged more recently (Reich Et al. 2010).<\/p>\n<figure style=\"width: 227px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image6-4-1.png\" alt=\"Molar tooth with wear, large surface area, and large roots.\" width=\"227\" height=\"341\" \/><figcaption class=\"wp-caption-text\">Figure 12.15: Reproduction of Denisovan molar. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Denisova_Molar.jpg\" target=\"_blank\">Denisova Molar<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Thilo_Parg\" target=\"_blank\">Thilo Parg<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Denisovans share up to 5% of their DNA with modern Melanesians, aboriginal Australians, and Polynesians, and 0.2% of their DNA with other modern Asian populations and Native Americans. Additional studies have suggested one (Vernot Et al. 2018) or two (Browning Et al. 2018) separate points of time when interbreeding occurred between modern humans and Denisovans.<\/p>\n<p class=\"import-Normal\">Genetic analysis reveals that Denisovans (potentially three distinct populations) had adaptations for life at high altitudes that prevented them from developing altitude sickness and hypoxia in extreme environments such as Tibet, where the average annual temperature is close to 0\u2103 and the altitude is more than a kilometre (about 4,000 feet) above sea level. Through protein analysis of a jawbone, one study (Chen Et al. 2019) has placed Denisovans in Tibet as early as 160,000 years ago. Genetic evidence of interbreeding has linked modern Tibetan populations with Denisovans 30,000 to 40,000 years ago, which implies that the unique high-altitude adaptations seen in modern Tibetans may have originated with Denisovans (Huerta-Sanchez Et al. 2014).<\/p>\n<p class=\"import-Normal\">Other research suggests tantalizing new directions regarding Denisovans. Stone tools similar to those found in Siberia have been uncovered in the Tibetan plateau suggesting a connection between the Denisovan populations in those two areas (Zhang Et al. 2018). The molar of a young girl, possibly Denisovan, has been found in Laos and shows strong similarities to specimens from China (Demeter Et al. 2022). And DNA sequencing from discoveries in the Denisova Cave have yielded a genome that has been interpreted as the first-generation offspring of a Denisovan father and Neanderthal mother (Slon Et al. 2018). While this research is not yet conclusive and is still being interpreted, exciting new possibilities are being revealed. To stay up-to-date with new discoveries, consider following organizations such as the <a href=\"https:\/\/www.facebook.com\/smithsonian.humanorigins\/\" target=\"_blank\">Smithsonian\u2019s Human Origins Program<\/a> on social media.<\/p>\n<div class=\"textbox\" style=\"background: var(--lightblue)\">\n<h2>Pleistocene Hominins in East Asia: Homo longi and Yunxian<\/h2>\n<p>New fossil discoveries, along with advanced molecular analysis, are prompting re-evaluations of the complex evolutionary dynamics of non-sapiens Homo in the middle-late Pleistocene.<\/p>\n<h3>Homo longi<\/h3>\n<p>The Harbin cranium, often referred to as Homo longi, represents one of the most remarkable Middle Pleistocene human fossils discovered in East Asia. It is currently carbon-dated at 146 ka, allowing recent scholarship to use the Harbin cranium to argue for a distinct clade of hominins that evolved independently in Eastern Asia, separate from Neanderthals and modern humans (Ni et al., 2021). This clade is argued to include Dali, Jinniushan, Hualongdong, Xiahe, and Harbin, based on phylogenetic analyses using parsimony criteria and Bayesian tip-dating, forming a third East Asian lineage and a sister group to the Homo sapiens lineage.<\/p>\n<p>The Harbin cranium exhibits a unique combination of traits, likely representing a species of Homo distinct from other Middle-to-Late Pleistocene taxa, including H. sapiens, H. Neanderthalensis, and H. Heidelbergensis\/H. Rhodesiensis. Its overall size is exceptional, setting it apart from nearly all other known fossils; however, the proportions of the cranial vault align closely with those of other large late archaic Homo species, with an estimated brain volume of approximately 1,420 mL. Despite its considerable breadth, the face is relatively low in height and exhibits a zygomaxillary shape similar to that seen in H. sapiens and H. antecessor, a feature also observed in other Middle Pleistocene Chinese fossils from Dali and Jinniushan. Additionally, the face is attached to the braincase with reduced prognathism, forming a more perpendicular angle as in modern humans, in contrast to the pronounced midfacial prognathism of Neanderthals.<\/p>\n<h3>Yunxian, China: Possible cladistic origins<\/h3>\n<p>In 2025, researchers released findings that expanded the diversity and relationships of Homo lineages in the Pleistocene, based on an analysis of fossils found in 1989\/90. Two skull fossils were found near the Hanjiang River in Hubei province, China, and were named the Yunxian 1 and Yunxian 2 crania\u2014A third cranium has recently been discovered in the same sediment layer as the two previous finds (Tu et al., 2026). The first 2 specimens were in poor condition, fragmented and distorted; however, using recently developed techniques such as high-resolution computed tomography (CT) scans, image segmentation, and digital repositioning of fragments, the researchers incorporated elements from the Yunxian 1 crania with the less damaged Yunxian 2 cranium. The Yunxian 2 cranium is a mosaic of primitive and derived traits. It retains ancient characteristics seen in earlier hominins, a thick supraorbital torus, a broad palate, a long and low vault in lateral view, and a receding frontal contour; its frontal lobe remains low and narrow, similar to H. erectus fossils. Conversely, it lacks the strongly angulated occipital bone found in H. erectus as well as the protruding occipital region or central suprainiac fossa typical of Neanderthals. The big surprise is that the zygomaxillary region is transversely flat and faces anteriorly, a feature comparable to the Hualongdong and Harbin fossils and even H. sapiens. This intermediate morphology places Yunxian 2 in a distinct position, linking archaics like H. erectus with later Asian hominins such as Harbin, Dali, and Jinniushan. Phylogenetic and morphometric analyses confirm that Yunxian 2 represents an early member of the Asian H.longi Clade. The reconstructed Yunxian 2 cranium represents a major achievement in paleoanthropology, digitally restoring a badly damaged fossil from beyond the Middle Pleistocene. In fact, recent discussion suggests an even earlier date for the Yunxian fossils at approximately 1.77 Ma (Tu et al., 2026). In their analysis, they identify the Yunxian fossils as H.erectus, and the site as Early Pleistocene. Over 500 artifacts have been recovered from the site (cores, choppers, and flakes) typical of the Early Paleolithic. Nevertheless, the mosaic morphology of the Yunxian skulls reveals characteristics within the range of both H. erectus and the Harbin skull (among others), which may position these finds as being very close to the origins and diversification of the longi clade, as well as preserving transitional features close to the sapiens clade\u00a0 (Feng et al., 2025, p.1323).<\/p>\n<p>The expanding fossil and genomic record of Archaic Homo has profoundly reshaped our understanding of Pleistocene human evolution. Discoveries, from an increasing variety of fossils found in eastern Asia, to advances in genomic research, demonstrate that multiple contemporaneous lineages once coexisted, interacted, diverged and, at times, interbred. These findings challenge earlier linear models of human ancestry and instead point to a dynamic evolutionary landscape marked by regional diversification, intermittent contact, and complex patterns of gene flow.<\/p>\n<\/div>\n<p>&nbsp;<\/p>\n<h2 class=\"import-Normal\">How Do These Fit In? <em>Homo naledi<\/em> and <em>Homo floresiensis<br \/>\n<\/em><\/h2>\n<p class=\"import-Normal\">Recently, some fossils have been unearthed that have challenged our understanding of the hominin lineage. The fossils of <em>Homo <\/em><em>naledi<\/em> and <em>Homo <\/em><em>floresiensis<\/em> are significant for several reasons but are mostly known for how they don\u2019t fit the previously held patterns of hominin evolution. While we examine information about these species, we ask you to consider the evidence presented in this chapter and others to draw your own conclusions regarding the significance and placement of these two unusual fossil species in the hominin lineage.<\/p>\n<h3 class=\"import-Normal\"><strong>Homo <\/strong><strong>naledi<\/strong><\/h3>\n<figure style=\"width: 347px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image12-5.png\" alt=\"A nearly complete skeleton surrounded by off-white bone fragments on a black table.\" width=\"347\" height=\"390\" \/><figcaption class=\"wp-caption-text\">Figure 12.16: A sample of some of the 1,550 bones found representing Homo naledi. Credit: <a href=\"https:\/\/elifesciences.org\/articles\/09560#fig1\" target=\"_blank\">Dinaledi skeletal specimens (Figure 1)<\/a> by <a href=\"https:\/\/elifesciences.org\/articles\/09560\" target=\"_blank\">Berger et al. 2015<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/legalcode\" target=\"_blank\">CC BY 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">In 2013 recreational spelunkers uncovered a collection of bones deep in a cave network in Johannesburg, South Africa. The cave system, known as Rising Star, had been well documented by other cavers; however, it appears few people had ever gone as far into the cave as these spelunkers did. Lee Berger, paleoanthropologist at University of Witwatersrand, in Johannesburg, immediately put out a call for what he termed \u201cunderground astronauts\u201d to begin recovery and excavation of the fossil materials. Unlike other excavations, Berger and most other paleoanthropologists would not be able to access the elusive site, as it was incredibly difficult to reach, and at some points there was only eight inches of space through which to navigate. The underground astronauts, all petite women anthropologists, were the only ones who were able to access this remarkable site. Armed with small excavation tools and a video camera, which streamed the footage up to the rest of the team at the surface, the team worked together and uncovered a total of 1,550 bones, representing at least 15 individuals, as seen in Figure 12.16. Later, an additional 131 bones, including an almost-complete cranium, were found in a nearby chamber of the cave, representing three more individuals (Figure 12.17). Berger called in a team of specialists to participate in what was dubbed \u201cPaleoanthropology Summer Camp.\u201d Each researcher specialized in a different portion of the hominin skeleton. With various specialists working simultaneously, more rapid analysis was possible of <em>Homo <\/em><em>naledi<\/em> than most fossil discoveries.<\/p>\n<p>&nbsp;<\/p>\n<figure style=\"width: 534px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image2-4.png\" alt=\"Photograph of four different views of the LES1 Homo naledi skull set against a black background.\" width=\"534\" height=\"599\" \/><figcaption class=\"wp-caption-text\">Figure 12.17: Several angles of the nearly complete LES1 Homo naledi skull. Credit: <a href=\"https:\/\/elifesciences.org\/articles\/24232#fig5\" target=\"_blank\">LES1 Cranium (Figure 5)<\/a> by <a href=\"https:\/\/elifesciences.org\/articles\/24232\" target=\"_blank\">Hawks et al. 2017<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/legalcode\" target=\"_blank\">CC BY 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">While access to the site, approximately 80 m from any known cave entrance or opening, was treacherous for researchers, it must have been difficult for <em>Homo <\/em><em>naledi<\/em> as well. The route included moving through a portion that is just 25 cm wide at some points, known as \u201cSuperman\u2019s Crawl.\u201d The only way to get through this section is by crawling on your stomach with one arm by your side and the other raised above your head. Past Superman\u2019s Crawl, a jagged wall known as the Dragon\u2019s Back would have been very difficult to traverse. Below that, a narrow vertical chute would have eventually led down to the area where the fossils were discovered. While geology changes over time and the cave system likely has undergone its fair share, it is not likely that these features arose after <em>Homo <\/em><em>naledi<\/em> lived (Dirks Et al. 2017). This has made scientists curious as to how the bones ended up in the bottom of the cave system in the first place. It has been suggested that <em>Homo <\/em><em>naledi<\/em> deposited the bones there, one way or another. If <em>Homo <\/em><em>naledi<\/em> did deposit the bones, either through random disposal or intentional burial, this raises questions regarding their symbolic behaviour and other cultural traits, including the use of fire, to access a very dark cave system. Another competing idea is that a few individuals may have entered the cave system to escape a predator and then got stuck. To account for the sheer number of fossils, this would have had to happen multiple times.<\/p>\n<p class=\"import-Normal\">The features of <em>Homo <\/em><em>naledi<\/em> are well-documented due to the fairly large sample, which represents individuals of all sexes and a wide range of ages. The skull shape and features are very much like other members of the genus <em>Homo<\/em>\u2014including a sagittal keel and large brow, like <em>Homo <\/em><em>erectus<\/em>, and a well-developed frontal lobe, similar to modern humans\u2014yet the brain size is significantly smaller than its counterparts, at approximately 500 cc (560 cc for males and 465 cc for females). The teeth also exhibit features of later members of the genus <em>Homo<\/em>, such as Neanderthals, including a reduction in overall tooth size. <em>Homo <\/em><em>naledi<\/em> also had unique shoulder anatomy and curved fingers, indicating similarities to tree-dwelling primates, which is very different from any other hominin yet found. Perhaps the greatest shock of all is that <em>Homo <\/em><em>naledi<\/em> has been dated to 335,000 to 236,000 years ago, placing it as a contemporary to modern <em>Homo sapiens,<\/em> despite its very primitive features. An additional specimen of a child, found in 2021, not only shares many of the unique features found in the adult specimen but will also add insight into the growth and development of individuals of this species (Brophy Et al. 2021).<\/p>\n<h3 class=\"import-Normal\"><strong>Homo <\/strong><strong>floresiensis<\/strong><\/h3>\n<p class=\"import-Normal\">In a small cave called Liang Bua, on the island of Flores, in Indonesia, a small collection of fossils were discovered beginning in 2003 (Figure 12.18). The fossil fragments represent as many as nine individuals, including a nearly complete female skeleton. The features of the skull are very similar to that of <em>Homo <\/em><em>erectus<\/em>, including the presence of a sagittal keel, an arching brow ridges and nuchal torus, and the lack of a chin (Figure 12.19). <em>Homo <\/em><em>floresiensis<\/em>, as the new species is called, had a brain size that was remarkably small at 400 cc, and recent genetic studies suggest a common ancestor with modern humans that predates <em>Homo <\/em><em>erectus<\/em>.<\/p>\n<figure style=\"width: 606px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image8-3.png\" alt=\"View from inside a large cave with people standing near a dug-out square of dirt.\" width=\"606\" height=\"403\" \/><figcaption class=\"wp-caption-text\">Figure 12.18: Liang Bua Cave on the island of Flores, in Indonesia, where a collection of Homo floresiensis specimens were discovered. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Homo_floresiensis_cave.jpg\" target=\"_blank\">Homo floresiensis cave<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/84301190@N00\" target=\"_blank\">Rosino<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\" target=\"_blank\">CC BY-SA 2.0 License<\/a>.<\/figcaption><\/figure>\n<figure style=\"width: 584px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image9-5.png\" alt=\"Photograph of a gray and off-white cast Homo floresiensis skull.\" width=\"584\" height=\"584\" \/><figcaption class=\"wp-caption-text\">Figure 12.19: Homo floresiensis had a brain that was remarkably small at 400 cc. Recent genetic studies suggest a common ancestor with modern humans that predates Homo erectus. Credit: <a href=\"https:\/\/boneclones.com\/product\/homo-floresiensis-skull-BH-033-2\" target=\"_blank\">Homo floresiensis Skull (Flores Skull LB1)<\/a> by <a href=\"https:\/\/boneclones.com\/\" target=\"_blank\">\u00a9BoneClones<\/a> is used by permission and available here under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">The complete female skeleton, who was an adult, was approximately a metre tall and would have weighed just under 30 kg, which is significantly shorter and just a few kilograms more than the average, modern, young elementary-aged child. A reconstructed comparison between an anatomically modern human and <em>Homo <\/em><em>floresiensis<\/em> can be seen in Figure 12.20. The small size of the fossil has earned the species the nickname \u201cthe Hobbit.\u201d Many questions have been asked about the stature of this species, as all of the specimens found also show evidence of diminutive stature and small brain size. Some explanations include pathology; however, this seems unlikely as all fossils found thus far demonstrate the same pattern. Another possible explanation lies in a biological phenomena seen in other animal species also found on the island, which date to a similar time period. This phenomenon, called <strong>insular dwarfing<\/strong>, is due to limited food resources on an island, which can create a selective pressure for large-bodied species to be selected for smaller size, as an island would not have been able to support their larger-bodied cousins for a long period of time. This phenomenon is the cause of other unique species known to have lived on the island at the same time, including the miniature stegodon, a dwarf elephant species.<\/p>\n<figure style=\"width: 448px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image18-4.png\" alt=\"Black-and-white drawing of a large nude woman and a much smaller man.\" width=\"448\" height=\"611\" \/><figcaption class=\"wp-caption-text\">Figure 12.20: A reconstructed comparison between an anatomically modern human and Homo floresiensis. As an adult, Homo floresiensis was approximately 1 metre tall and would have weighed under 30 kg. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-16\/\" target=\"_blank\">Anatomically modern human and Homo floresiensis (Figure 11.19)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">There is ongoing research and debate regarding <em>Homo floresiensis<\/em>\u2019 dates of existence, with some researchers concluding that they lived on Flores until perhaps as recently as 17,000 years ago, although they are more often dated to 100,000 to 60,000 years ago. Stone tools from that time period uncovered at the site are similar to other hominin stone tools found on the island of Flores. <em>Homo <\/em><em>floresiensis<\/em> would have hunted a wide range of animals, including the miniature stegodon, giant rats, and other large rodents. Other animals on the island that could have threatened them include the giant komodo dragon. An interesting note about this island chain is that ancestors of <em>Homo <\/em><em>floresiensis<\/em> would have had to traverse the open ocean in order to get there, as the nearest island is almost 10 km away, and there is little evidence to support that a land bridge connecting mainland Asia or Australia to the island would have been present. This separation from the mainland would also have limited the number of other animals, including predators and human species, that would have had access to the island. Anatomically modern <em>Homo sapiens<\/em> arrived on the island around 30,000 years ago and, if some researchers\u2019 later dates for <em>Homo <\/em><em>floresiensis<\/em> are correct, both species may have lived on Flores at the same time. The modern population living on the island of Flores today believes that their ancestors came from the Liang Bua cave; however, recent genetic studies have determined they are not related to <em>Homo <\/em><em>floresiensis<\/em> (Tucci Et al. 2018).<\/p>\n<h2>Cultural Connections and Contemporary Implications<\/h2>\n<p>The Neanderthals provide an important example of how biological and cultural adaptations cannot always be understood separately. Their large brains and robust, cold-adapted bodies came with significant energetic demands, creating biological challenges that could be addressed through cultural practices. Hunting, tool use, food processing, fire, clothing, and shelter were not simply behaviours that existed alongside their biology; they allowed Neanderthals to respond to the environment and the physiological demands placed on their bodies. In this sense, culture became another means through which Neanderthals adapted to their environment.<\/p>\n<p>Their social behaviours further complicate the distinction between biological survival and cultural adaptation. Evidence of care for injured or vulnerable individuals and intentional burial suggests that their social lives extended beyond immediate individual survival. These social interactions demonstrate that adaptation was not simply a matter of being biologically suited to an environment, but also involved relationships, shared practices, and forms of social care. Although the meaning of these behaviours cannot be fully reconstructed, they challenge the simplistic image of archaic humans as primitive or solely driven by biological instincts.<\/p>\n<p>Ultimately, Neanderthals demonstrate that human adaptation is neither exclusively biological nor exclusively cultural. Their bodies were shaped by the environments in which they lived, while their cultural practices allowed them to navigate and modify those environments. Looking at Neanderthals through a biocultural perspective therefore moves us beyond the idea of the \u201ccaveman\u201d and instead recognizes them as hominins whose survival emerged through the interaction of physiology, environment, technology, and social life.<\/p>\n<h4>Discussion questions<\/h4>\n<ul>\n<li>Why might caring for the sick and injured and practicing burial rites be considered evidence of culture? What do these behaviours reveal about social life?<\/li>\n<li>Can you think of an example of the intertwining of biology and culture in humans today? What does this example reveal about the relationship between biological and cultural adaptation?<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n<div class=\"textbox\">\n<h2 class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">Hominin Species Summaries<\/span><\/h2>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<tbody>\n<tr class=\"Table3-R\" style=\"height: 0\">\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Hominin<\/strong><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Archaic <em>Homo sapiens<\/em><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 0\">\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dates<\/strong><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">600,000\u2013200,000 years ago (although some regional variation)<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 0\">\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Region(s)<\/strong><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Africa, Europe, and Asia<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 0\">\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Famous discoveries<\/strong><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Broken Hill (Zambia), Atapuerca (Spain)<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 0\">\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Brain size<\/strong><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1,200 cc average<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 0\">\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dentition<\/strong><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Slightly smaller teeth in back of mouth, larger front teeth<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 0\">\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Cranial features<\/strong><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Emerging forehead, no chin, projecting occipital region<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 0\">\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Postcranial features<\/strong><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Robust skeleton<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 0\">\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Culture<\/strong><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Varied regionally, but some continue to use Acheulean handaxe, others adopt Mousterian tool culture<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table3-R\" style=\"height: 0\">\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Other <\/strong><\/p>\n<\/td>\n<td class=\"Table3-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Lots of regional variation in this species<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<tbody>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Species<\/strong><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><em>Homo <\/em><em>naledi<\/em><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dates<\/strong><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">335,000\u2013236,000 years ago<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Region(s)<\/strong><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">South Africa<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Famous discoveries<\/strong><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Rising Star Cave<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Brain size<\/strong><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">500 cc average<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dentition<\/strong><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Reduced tooth size<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Cranial features<\/strong><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Sagittal keel, large brow, well-developed frontal region<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Postcranial features<\/strong><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Suspensory shoulder<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Culture<\/strong><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">unknown<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table4-R\" style=\"height: 0\">\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Other<\/strong><\/p>\n<\/td>\n<td class=\"Table4-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">N\/A<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<tbody>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Hominin<\/strong><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Neanderthals<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dates<\/strong><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">150,000\u201340,000 years ago<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Region(s)<\/strong><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Western Europe, Middle East, and Western Asia only<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Famous discoveries<\/strong><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Shanidar (Iraq), La Chapelle-aux-Saints (France)<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Brain size<\/strong><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">1500 cc average<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dentition<\/strong><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Retromolar gap<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Cranial features<\/strong><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Large brow ridge, midfacial prognathism, large infraorbital foramina, occipital bun<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Postcranial features<\/strong><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Robust skeleton with short and stocky body, increased musculature, barrel chest<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Culture<\/strong><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Mousterian tools often constructed using the Levallois technique<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table5-R\" style=\"height: 0\">\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Other<\/strong><\/p>\n<\/td>\n<td class=\"Table5-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">N\/A<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<tbody>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Species<\/strong><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><em>Homo <\/em><em>floresiensis<\/em><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dates<\/strong><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">100,000\u201360,000 years ago, perhaps as recently as 17,000 years ago<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Region(s)<\/strong><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Liang Bua, island of Flores, Indonesia<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Famous discoveries<\/strong><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">\u201cThe Hobbit\u201d<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Brain size<\/strong><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">400 cc average<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dentition<\/strong><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">unknown<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Cranial features<\/strong><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Sagittal keel, arching brow ridges, nuchal torus, no chin<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Postcranial features<\/strong><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Very short stature (approximately 3.5 ft.)<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Culture<\/strong><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Tools similar to other tools found on the island of Flores<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table6-R\" style=\"height: 0\">\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Other<\/strong><\/p>\n<\/td>\n<td class=\"Table6-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">N\/A<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 468pt\">\n<tbody>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Hominin<\/strong><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Denisovans<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dates<\/strong><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">100,000\u201330,000 years ago<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Region(s)<\/strong><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Siberia<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Famous discoveries<\/strong><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Child\u2019s finger bone and adult molar<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Brain size<\/strong><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">unknown<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Dentition<\/strong><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Large molars (from limited evidence)<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Cranial features<\/strong><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">unknown<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Postcranial features<\/strong><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">unknown<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Culture<\/strong><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">unknown<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table7-R\" style=\"height: 0\">\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><strong>Other <\/strong><\/p>\n<\/td>\n<td class=\"Table7-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\">Closely related to Neanderthals (genetically)<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div class=\"textbox shaded\">\n<h2 class=\"import-Normal\">Summary<\/h2>\n<p class=\"import-Normal\">Research presented in the chapter contributes to why scientists have taken to nicknaming this time period \u201cthe muddle in the middle.\u201d We know that the Middle Pleistocene picks up from <em>Homo erectus <\/em>and ends with the appearance of anatomically modern <em>Homo sapiens<\/em>. While the start and the end are clear, it\u2019s the middle that is messy. As more research is conducted and more data is collected, rather than clarifying our understanding of the hominin lineage during this time period, it only inspires more questions, particularly about the relationships between hominins during this time period, including the oft-misunderstood Neanderthal. Research is painting a more detailed picture of Neanderthal intelligence and both biological and behavioural adaptations. At the same time, their relationship to other Middle Pleistocene hominins, including Denisovans, as well as modern humans, remains unclear.<\/p>\n<p class=\"import-Normal\"><em>Homo<\/em> <em>naledi<\/em> and <em>Homo <\/em><em>floresiensis<\/em> are clear outliers when compared to their contemporary hominin species. Each has surprised paleoanthropologists for both their archaic traits in relatively modern times and their unique combination of traits seen in archaic species and modern humans. While these finds have been exciting, they have also completely upended the assumed trajectory of the human lineage, causing scientists to re-examine assumptions about hominin evolution and what it means to be modern. Add this to the developments being made using ancient DNA, other new fossil discoveries, and other innovations in paleoanthropology, and you see that our understanding of Archaic <em>Homo sapiens<\/em> and others living during this time period is rapidly developing and changing. This is a true testament to the nature of science and the scientific method.<\/p>\n<p class=\"import-Normal\">Clearly, hominins of the Middle Pleistocene are distinct from our species today. Yet, understanding the hominins that directly preceded our species and clarifying the evolutionary relationships between us is important to better understanding our own place in nature.<\/p>\n<h2 class=\"import-Normal\">Review Questions<\/h2>\n<ul>\n<li>What physical and cultural features are unique to Archaic<em> Homo sapiens<\/em>? How are Archaic<em> Homo sapiens<\/em> different in both physical and cultural characteristics from <em>Homo <\/em><em>erectus<\/em>?<\/li>\n<li>Describe the specific changes to the brain and skull first seen in Archaic<em> Homo sapiens<\/em>. Why does the shape of the skull change so dramatically from <em>Homo <\/em><em>erectus<\/em>?<\/li>\n<li>What role did the shifting environment play in the adaptation of Archaic <em>Homo sapiens<\/em>, including Neanderthals? Discuss at least one physical feature and one cultural feature that would have assisted these groups in surviving the changing environment.<\/li>\n<li>What does the regional variation in Archaic <em>Homo sapiens<\/em> represent in terms of the broader story of our species\u2019 evolution?<\/li>\n<li>Describe the issues raised by the discoveries of <em>Homo <\/em><em>naledi<\/em> and <em>Homo <\/em><em>floresiensis<\/em> in the understanding of the story of the evolution of <em>Homo sapiens<\/em>.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<h2 class=\"__UNKNOWN__\">Key Terms<\/h2>\n<div class=\"__UNKNOWN__\">\n<p><strong>Allele<\/strong>: Each of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome.<\/p>\n<p class=\"import-Normal\"><strong>Anthropocentrism<\/strong>: A way of thinking that assumes humans are the most important species and leads to interpreting the world always through a human lens. Species-centric science and thought.<\/p>\n<p class=\"import-Normal\"><strong>Cortex<\/strong>: The outside, or rough outer covering, of a rock. Usually the cortex is removed during the process of stone tool creation.<\/p>\n<p class=\"import-Normal\"><strong>Ethnocentric<\/strong>: Applying negative judgments to other cultures based on comparison to one\u2019s own.<\/p>\n<p class=\"import-Normal\"><strong>Exogenous DNA<\/strong>: DNA that originates from sources outside of the specimen you are trying to sequence.<\/p>\n<p class=\"import-Normal\"><strong>Flexed position<\/strong>: Fetal position, in which the legs are drawn up to the middle of the body and the arms are drawn toward the body centre. Intentional burials are often found in the flexed body position.<\/p>\n<p class=\"import-Normal\"><strong>Foraminifera<\/strong>: Microscopic single-celled organisms with a shell that are common in all marine environments. The fossil record of foraminifera extends back well over 500 million years.<\/p>\n<p class=\"import-Normal\"><strong>Glaciation<\/strong>: A glacial period, or time when a large portion of the world is covered by glaciers and ice sheets.<\/p>\n<p class=\"import-Normal\"><strong>Globular<\/strong>: Round-shaped, like a globe.<\/p>\n<p class=\"import-Normal\"><strong>Grave goods<\/strong>: Items included with a body at burial. Items may signify occupation or hobbies, social status, or level of importance in the community, or they may be items believed necessary for the afterlife.<\/p>\n<p class=\"import-Normal\"><strong>Haft<\/strong>: A handle. Also used as a verb\u2014to attach a handle to an item, such as a stone tool.<\/p>\n<p class=\"import-Normal\"><strong>Infraorbital foramina<\/strong>: Small holes on the maxilla bone of the face that allows nerves and blood to reach the skin.<\/p>\n<p class=\"import-Normal\"><strong>Insular dwarfing<\/strong>: A form of dwarfism that occurs when a limited geographic region, such as an island, causes a large-bodied animal to be selected for a smaller body size.<\/p>\n<p class=\"import-Normal\"><strong>Interglacial<\/strong>: A warmer period between two glacial time periods.<\/p>\n<p class=\"import-Normal\"><strong>Levallois technique<\/strong>: A distinctive technique of stone tool manufacturing used by Archaic <em>Homo sapiens<\/em>, including Neanderthals. The technique involves the preparation of a core and striking edges off in a regular fashion around the core. Then a series of similarly sized pieces can be removed, which can then be turned into different tools.<\/p>\n<p class=\"import-Normal\"><strong>Midfacial prognathism<\/strong>: A forward projection of the nose or the middle facial region. Usually associated with Neanderthals.<\/p>\n<p class=\"import-Normal\"><strong>Mousterian tools<\/strong>: The stone tool industry of Neanderthals and their contemporaries in Africa and Western Asia. Mousterian tools are known for a diverse set of flake tools, which is different from the large bifacial tools of the Acheulean industry.<\/p>\n<p class=\"import-Normal\"><strong>Nasal aperture<\/strong>: The opening for the nose visible on a skull. Often pear- or heart-shaped.<\/p>\n<p class=\"import-Normal\"><strong>Occipital bun<\/strong>: A prominent bulge or projection on the back of the skull, specifically the occipital bone. This is a feature present only on Neanderthal skulls.<\/p>\n<p class=\"import-Normal\"><strong>Ochre<\/strong>: A natural clay pigment mixed with ferric oxide and clay and sand. Ranges in colour from brown to red to orange.<\/p>\n<p class=\"import-Normal\"><strong>Retracted face<\/strong>: A face that is flatter.<\/p>\n<p class=\"import-Normal\"><strong>Retromolar gap<\/strong>: A space behind the last molar and the end of the jaw. This is a feature present only on Neanderthals. It also occurs through cultural modification in modern humans who have had their third molars, or wisdom teeth, removed.<\/p>\n<h2 class=\"import-Normal\">For Further Exploration<\/h2>\n<p><a href=\"https:\/\/www.amnh.org\/exhibitions\/permanent-exhibitions\/anne-and-bernard-spitzer-hall-of-human-origins\">Anne and Bernard Spitzer Hall of Human Origins<\/a>\u2014American Museum of Natural History.<\/p>\n<p>\u201cDawn of Humanity,\u201d PBS documentary, 2015<\/p>\n<p><a href=\"https:\/\/www.ted.com\/talks\/svante_paeaebo_dna_clues_to_our_inner_neanderthal?language=en\" target=\"_blank\">\u201cDNA Clues to Our Inner Neanderthal,\u201d<\/a> TED Talk by Svante P\u00e4\u00e4bo, 2011.<\/p>\n<p>\u201cThe Dirt\u201d Podcast, Episode 30, <a href=\"https:\/\/thedirtpod.com\/episodes\/\/episode-30-the-human-family-tree-shrub-crabgrass-tumbleweed-part-3\" target=\"_blank\">\u201cThe Human Family Tree (Shrub? Crabgrass? Tumbleweed?), Part 3: Very Humany Indeed\u201d<\/a>.<\/p>\n<p class=\"import-Normal\"><a href=\"https:\/\/www.efossils.org\/page\/games-and-activities\" target=\"_blank\">eFossil Games and Activities<\/a><\/p>\n<p>Frank, Rebecca. 2021. \u201cThe Genus Homo.\u201d In <a href=\"https:\/\/explorations.americananthro.org\/index.php\/lab-and-activities-manual\/\" target=\"_blank\"><em>Explorations: Lab and Activity Manual, <\/em><\/a>edited by Beth Shook, Katie Nelson, Kelsie Aguilera, and Lara Braff. Arlington, VA: American Anthropological Association.<\/p>\n<p><a href=\"https:\/\/humanorigins.si.edu\/research\/asian-research-projects\/hobbits-flores-indonesia.\" target=\"_blank\">Hobbits on Flores, Indonesia<\/a> - Smithsonian Human Origins.<\/p>\n<p><a href=\"https:\/\/evolution.berkeley.edu\/evo-news\/lumping-or-splitting-in-the-fossil-record\/\" target=\"_blank\">Lumping or Splitting in the Fossil Record<\/a> - UC Berkeley Understanding Evolution.<\/p>\n<p><a href=\"https:\/\/www.eva.mpg.de\/genetics\/neandertals-and-more\/overview\/\" target=\"_blank\">Neandertals and More<\/a> - Max Planck Institute for Evolutionary Anthropology.<\/p>\n<p><a href=\"https:\/\/www.sapiens.org\/biology\/neanderthal-anatomy\/?fbclid=IwAR2Bcff1GVkTLnbCR58JAWiJzkk-Ell7zL0FUddf1HNAX6RDAZxbqh1zWoI\" target=\"_blank\">Neanderthals: Body of Evidence<\/a> - SAPIENS.<\/p>\n<p>Perash, Rose L., and Kristen A. Broehl. 2021. \u201cHominin Review: Evolutionary Trends.\u201d In <a href=\"https:\/\/explorations.americananthro.org\/index.php\/lab-and-activities-manual\/.\" target=\"_blank\"><em>Explorations: Lab and Activity Manual<\/em><\/a>, edited by Beth Shook, Katie Nelson, Kelsie Aguilera, and Lara Braff. Arlington, VA: American Anthropological Association.<\/p>\n<p>Perkl, Bradley. \u201cBrain, Language, Lithics.\u201d In <a href=\"https:\/\/explorations.americananthro.org\/index.php\/lab-and-activities-manual\/.\" target=\"_blank\"><em>Explorations: Lab and Activity Manual<\/em><\/a>, edited by<em>.<\/em> Beth Shook, Katie Nelson, Kelsie Aguilera, and Lara Braff. CC BY-NC. Arlington, VA: American Anthropological Association.<\/p>\n<p><a href=\"https:\/\/humanorigins.si.edu\/evidence\/human-fossils\/shanidar-3-neanderthal-skeleton\" target=\"_blank\">Shanidar 3 - Neanderthal Skeleton<\/a> - Smithsonian Human Origins.<\/p>\n<p><a href=\"https:\/\/humanorigins.si.edu\/evidence\/human-fossils\/species\" target=\"_blank\">Species<\/a> - Smithsonian Human Origins.<\/p>\n<p><a href=\"https:\/\/www.facebook.com\/smithsonian.humanorigins\/\" target=\"_blank\">Smithsonian Human Origins Program Facebook page<\/a> (@smithsonian.humanorigins).<\/p>\n<p><a href=\"https:\/\/www.smithsonianmag.com\/science-nature\/bringing-human-evolution-life-180951155\/\" target=\"_blank\">Paleoartist Brings Human Evolution to Life<\/a> - Elisabeth Dayn\u00e9s.<\/p>\n<h2 class=\"import-Normal\">References<\/h2>\n<p>Ackermann, Rebecca R., Matthew L. 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Living on the Edge: Was Demographic Weakness the Cause of Neanderthal Demise? <em>PLoS ONE<\/em> 14 (5): e0216742.<br style=\"clear: both\" \/><a class=\"rId130\" href=\"https:\/\/doi.org\/10.1371\/journal.pone.0216742.\" target=\"_blank\">https:\/\/doi.org\/<\/a><a class=\"rId131\" href=\"https:\/\/doi.org\/10.1371\/journal.pone.0216742.\" target=\"_blank\">10.1371\/journal.pone.0216742.<\/a><\/p>\n<p class=\"import-Normal\">Delpiano, Davide, Kristin Heasley, and Marci Peresani. 2018. \u201cAssessing Neanderthal Land Use and Lithic Raw Material Management in Discoid Technology.\u201d <em>Journal of Anthropological Sciences<\/em> 96: 89\u2013110. <a class=\"rId132\" href=\"https:\/\/doi.org\/10.4436\/jass.96006.\">https:\/\/doi.org\/<\/a><a class=\"rId133\" href=\"https:\/\/doi.org\/10.4436\/jass.96006.\" target=\"_blank\">10.4436\/jass.96006.<\/a><\/p>\n<p class=\"import-Normal\">Demeter, Fabrice, Cl\u00e9ment Zanolli, Kira E. Westaway, Renaud Joannes-Boyau, Phillippe Duringer, Mike W. Morley, Frido Welker, et al. 2022. \u201cA Middle Pleistocene Denisovan Molar from the Annamite Chain of Northern Laos.\u201d <em>Nature Communications<\/em> 13 (1): 2557. <a class=\"rId134\" href=\"https:\/\/doi.org\/10.7554\/eLife.24231.\" target=\"_blank\">https:\/\/doi.org\/10.7554\/eLife.24231.<\/a><\/p>\n<p class=\"import-Normal\">Dirks, Paul H. G. M., Eric M. Roberts, Hannah Hilbert-Wolf, Jan D. 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L., B. B. Ha, S. J. Wang, Z. J. Chen, J. Y. Ge, H. Long, W. He, et al. 2018. \u201cThe Earliest Human Occupation of the High-Altitude Tibetan Plateau 40 Thousand to 30 Thousand Years Ago.\u201d <em>Science<\/em> 362 (6418): 1049\u20131051. <a class=\"rId177\" href=\"https:\/\/doi.org\/10.1126\/sciadv.add5582.\" target=\"_blank\">https:\/\/doi.org\/10.1126\/sciadv.add5582.<\/a><\/p>\n<p>Zeberg, Hugo, Mattias Jakobsson, &amp; Svante P\u00e4\u00e4bo. (2024). \u201cThe Genetic Changes That Shaped Neandertals, Denisovans, and Modern Humans.\u201d Cell 187, no. 5:1047\u20131058. <a href=\"https:\/\/doi.org\/10.1016\/j.cell.2023.12.029\" target=\"_blank\">https:\/\/doi.org\/10.1016\/j.cell.2023.12.029<\/a>.<\/p>\n<p class=\"import-Normal\">Zilh\u00e3o Jo\u00e3o, Diego E. Angelucci, Ernestina Badal-Garc\u00eda, Francesco d'Errico, Flor\u00e9al Daniel, Laure Dayet, Katerina Douka, et al. 2010. \u201cSymbolic Use of Marine Shells and Mineral Pigments by Iberian Neandertals.\u201d <em>Proceedings of the National Academy of Sciences<\/em> 107 (3): 1023\u20131028. <a class=\"rId178\" href=\"https:\/\/doi.org\/10.1073\/pnas.0914088107.\">https:\/\/doi.org\/<\/a><a class=\"rId179\" href=\"https:\/\/doi.org\/10.1073\/pnas.0914088107.\" target=\"_blank\">10.1073\/pnas.0914088107.<\/a><\/p>\n<p class=\"import-Normal\">Zollikofer, Christopher Peter Edwards, and Marcia Silvia Ponce de Le\u00f3n. 2013. \u201cPandora\u2019s Growing Box: Inferring the Evolution and Development of Hominin Brains from Endocasts.\u201d Evolutionary Anthropology 22 (1): 20\u201333. <a class=\"rId180\" href=\"https:\/\/doi.org\/10.1002\/evan.21333.\" target=\"_blank\">https:\/\/doi.org\/10.1002\/evan.21333.<\/a><\/p>\n<h2>Acknowledgements<\/h2>\n<p class=\"import-Normal\">The authors would like to extend their thanks to Cassandra Gilmore and Anna Goldfield for thoughtful and insightful suggestions on the first edition of this chapter.<\/p>\n<\/div>\n<\/div>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1695_1880\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1695_1880\"><div tabindex=\"-1\"><div class=\"__UNKNOWN__\">\n<div class=\"textbox\">\n<h6>Student contributors to this chapter: Lily Berruyer, Lyn Loytchenko, and Sarah Cupidio<\/h6>\n<p>Learn more about <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/about-the-authors\/\">authors and editors<\/a>,<a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/student-contributors\/\"> Hess' student contributions<\/a>, and <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/versioning-history\/\">versioning history<\/a>.<\/p>\n<\/div>\n<div class=\"textbox textbox--learning-objectives\">\n<header class=\"textbox__header\">\n<h2 class=\"textbox__title\">Learning Objectives<\/h2>\n<\/header>\n<div class=\"textbox__content\">\n<ul>\n<li>Identify the skeletal and behavioural traits that represent modern <em>Homo sapiens.<\/em><\/li>\n<li>Critically evaluate different types of evidence for the origin of our species in Africa and our expansion around the world.<\/li>\n<li>Understand how the human lifestyle changed when people transitioned from foraging to agriculture.<\/li>\n<li>Hypothesize how human evolutionary trends may continue into the future.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<p class=\"import-Normal\">The walls of a pink limestone cave in the hillside of Jebel Irhoud jutted out of the otherwise barren landscape of the Moroccan desert (Figure 13.1). Miners had excavated the cave in the 1960s, revealing some fossils. In 2007, a re-excavation of the site became a momentous occasion for science. A fossil cranium unearthed by a team of researchers was barely visible to the untrained eye. Just the fossil\u2019s robust brows were peering out of the rock. This research team from the Max Planck Institute for Evolutionary Anthropology was the latest to explore the ancient human presence in this part of North Africa after a find by miners in 1960. Excavating near the first discovery, the researchers wanted to learn more about how <em>Homo sapiens<\/em> lived far from East Africa, where we thought our species originated.<\/p>\n<figure style=\"width: 2500px\" class=\"wp-caption alignnone\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2023\/06\/image10-1.jpg\" alt=\"Rocky hillside with exposed layers. People are visible at the base.\" width=\"2500\" height=\"987\" \/><figcaption class=\"wp-caption-text\">Figure 13.1: The excavation of an exposed cave at Jebel Irhoud, Morocco, where hominin fossils were found in the 1960s and in 2007. Dating showed that they could represent the earliest-known modern Homo sapiens. Credit: <a href=\"https:\/\/www.eva.mpg.de\/homo-sapiens\/presskit.html\">View looking south of the Jebel Irhoud (Morocco) site<\/a> by Shannon McPherron, <a href=\"https:\/\/www.eva.mpg.de\/index.html\">MPI EVA Leipzig<\/a>, is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/\">CC BY-SA 2.0 License<\/a>.<\/figcaption><\/figure>\n<p>The scientists were surprised when they analysed the cranium, named Irhoud 10, and other fossils. Statistical comparisons with other human crania concluded that the Irhoud face shapes were typical of recent modern humans while the braincases matched ancient modern humans. Based on the findings of other scientists, the team expected these modern <em>Homo sapiens<\/em> fossils to be around 200,000 years old. Instead, dating revealed that the cranium had been buried for around 315,000 years.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Together, the modern-looking facial dimensions and the older date reshaped the interpretation of our species: modern <em>Homo sapiens<\/em>. Some key evolutionary changes from the archaic <em>Homo sapiens<\/em> (described in Chapter 12) to our species today happened 100,000 years earlier than we had thought and across the vast African continent rather than concentrated in its eastern region.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">This revelation in the study of modern <em>Homo sapiens<\/em> is just one of the latest in this continually advancing area of biological anthropology. Researchers today are still discovering amazing fossils and ingenious ways to collect data and test hypotheses about our past. Through the collective work of many scientists, we are building an overall theory of modern human origins.<\/p>\n<h2 class=\"import-Normal\">Defining Modernity<\/h2>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">What defines modern <em>Homo sapiens<\/em> when compared to archaic <em>Homo sapiens<\/em>? Modern humans, like you and me, have a set of derived traits that are not seen in archaic humans or any other hominin. As with other transitions in hominin evolution, such as increasing brain size and bipedal ability, modern traits do not appear fully formed or all at once. In other words, the first modern <em>Homo sapiens<\/em> was not just born one day from archaic parents. The traits common to modern <em>Homo sapiens<\/em> appeared in a <strong>mosaic<\/strong> manner: gradually and out of sync with one another. There are two areas to consider when tracking the complex evolution of modern human traits. One is the physical change in the skeleton. The other is behaviour inferred from the size and shape of the cranium and material culture evidence.<\/p>\n<h3 class=\"import-Normal\"><strong>Skeletal Traits<\/strong><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The skeleton of modern <em>Homo sapiens<\/em> is less robust than that of archaic <em>Homo sapiens<\/em>. In other words, the modern skeleton is <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1406\">gracile<\/a><\/strong>, meaning that the structures are thinner and smoother. Differences related to gracility in the cranium are seen in the braincase, the face, and the mandible. There are also broad differences in the rest of the skeleton.<\/p>\n<h4 class=\"import-Normal\"><em>Cranial Traits<\/em><\/h4>\n<figure style=\"width: 445px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image29-2.png\" alt=\"A rounded skull facing a robust skull with sloping forehead.\" width=\"445\" height=\"221\" \/><figcaption class=\"wp-caption-text\">Figure 13.2: Comparison between modern (left) and archaic (right) Homo sapiens skulls. Note the overall gracility of the modern skull, as well as the globular braincase. Credit: <a class=\"rId15\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-14\/\">Modern human and Neanderthal<\/a> original to <a class=\"rId16\" href=\"https:\/\/explorations.americananthro.org\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a class=\"rId17\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Several elements of the braincase differ between modern and archaic <em>Homo sapiens<\/em>. Overall, the shape is much rounder, or more <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1758\"><strong>globular<\/strong>,<\/a> on a modern skull (Lieberman, McBratney, and Krovitz 2002; Neubauer, Hublin, and Gunz 2018; Pearson 2008; Figure 13.2). You can feel the globularity of your own modern human skull. Feel the height of your forehead with the palm of your hand. Viewed from the side, the tall vertical forehead of a modern <em>Homo sapiens<\/em> stands out when compared to the sloping archaic version. This is because the frontal lobe of the modern human brain is larger than the one in archaic humans, and the skull has to accommodate the expansion. The vertical forehead reduces a trait that is common to all other hominins: the brow ridge or <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1759\">supraorbital torus<\/a><\/strong>. The parietal lobes of the brain and the matching parietal bones on either side of the skull both bulge outward more in modern humans. At the back of the skull, the archaic occipital bun is no longer present. Instead, the occipital region of the modern human cranium has a derived tall and smooth curve, again reflecting the globular brain inside.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The trend of shrinking face size across hominins reaches its extreme with our species as well. The facial bones of a modern <em>Homo sapiens<\/em> are extremely gracile compared to all other hominins (Lieberman, McBratney, and Krovitz 2002). Continuing a trend in hominin evolution, technological innovations kept reducing the importance of teeth in reproductive success (Lucas 2007). As natural selection favoured smaller and smaller teeth, the surrounding bone holding these teeth also shrank.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Related to smaller teeth, the mandible is also gracile in modern humans when compared to archaic humans and other hominins. Interestingly, our mandibles have pulled back so far from the prognathism of earlier hominins that we gained an extra structure at the most anterior point, called the <strong>mental eminence<\/strong>. You know this structure as the chin. At the skeletal level, it resembles an upside-down \u201cT\u201d at the centreline of the mandible (Pearson 2008). Looking back at archaic humans, you will see that they all lack a chin. Instead, their mandibles curve straight back without a forward point. What is the chin for and how did it develop? Flora Gr\u00f6ning and colleagues (2011) found evidence of the chin\u2019s importance by simulating physical forces on computer models of different mandible shapes. Their results showed that the chin acts as structural support to withstand strain on the otherwise gracile mandible.<\/p>\n<h4 class=\"import-Normal\"><em>Postcranial Gracility<\/em><\/h4>\n<figure style=\"width: 368px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image16-5.png\" alt=\"Two complete skeletons. The left is taller with a thinner frame.\" width=\"368\" height=\"575\" \/><figcaption class=\"wp-caption-text\">Figure 13.3: Anterior views of modern (left) and archaic (right) Homo sapiens skeletons. The modern human has an overall gracile appearance at this scale as well. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-14\/\">Modern and archaic Homo sapiens skeletons (Figure 12.3)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p>The rest of the modern human skeleton is also more gracile than its archaic counterpart. The differences are clear when comparing a modern <em>Homo sapiens<\/em> with a cold-adapted Neanderthal (Sawyer and Maley 2005), but the trends are still present when comparing modern and archaic humans within Africa (Pearson 2000). Overall, a modern <em>Homo sapiens<\/em> postcranial skeleton has thinner cortical bone, smoother features, and more slender shapes when compared to archaic <em>Homo sapiens<\/em> (Figure 13.3). Comparing whole skeletons, modern humans have longer limb proportions relative to the length and width of the torso, giving us lankier outlines.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Why is our skeleton so gracile compared to those of other hominins? Natural selection can drive the gracilization of skeletons in several ways (Lieberman 2015). A slender frame is believed to be adapted for the efficient long-distance running ability that started with <em>Homo erectus<\/em>. Furthermore, it is argued that slenderness is a genetic adaptation for cooling an active body in hotter climates, which aligns with the ample evidence that Africa was the home continent of our species.<\/p>\n<h3 class=\"import-Normal\"><strong>Behavioural Modernity<\/strong><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Aside from physical differences in the skeleton, researchers have also uncovered evidence of behavioural changes associated with increased cultural complexity from archaic to modern humans. How did cultural complexity develop? Two investigations into this question are archaeology and the analysis of reconstructed brains.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Archaeology tells us much about the behavioural complexity of past humans by interpreting the significance of material culture. In terms of advanced culture, items created with an artistic flair, or as decoration, speak of abstract thought processes (Figure 13.4). The demonstration of difficult artistic techniques and technological complexity hints at social learning and cooperation as well. According to paleoanthropologist John Shea (2011), one way to track the complexity of past behaviour through artifacts is by measuring the variety of tools found together. The more types of tools constructed with different techniques and for different purposes, the more modern the behaviour. Researchers are still working on an archaeological way to measure cultural complexity that is useful across time and place.<\/p>\n<figure style=\"width: 221px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image15-1-1.jpg\" alt=\"A brown standing statue of a human figure with cat\u2019s head.\" width=\"221\" height=\"392\" \/><figcaption class=\"wp-caption-text\">Figure 13.4: Carved ivory figure called \u201cthe Lion-Man of the Hohlenstein-Stadel.\u201d It dates to the Aurignacian culture, between 35 and 40 kya. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Loewenmensch1.jpg\">Loewenmensch1<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Dagmar_Hollmann\">Dagmar Hollmann<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The interpretation of brain anatomy is another promising approach to studying the evolution of human behaviour. When looking at investigations on this topic in modern <em>Homo sapiens<\/em> brains, researchers found a weak association between brain size and test-measured intelligence (Pietschnig Et al. 2015). Additionally, they found no association between intelligence and biological sex. These findings mean that there are more significant factors that affect tested intelligence than just brain size. Since the sheer size of the brain is not useful for weighing intelligence within a species, paleoanthropologists are instead investigating the differences in certain brain structures. The differences in organization between modern <em>Homo sapiens<\/em> brains and archaic <em>Homo sapiens<\/em> brains may reflect different cognitive priorities that account for modern human culture. As with the archaeological approach, new discoveries will refine what we know about the human brain and apply that knowledge to studying the distant past.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Taken together, the cognitive abilities in modern humans may have translated into an adept use of tools to enhance survival. Researchers Patrick Roberts and Brian A. Stewart (2018) call this concept the <strong>generalist-specialist niche<\/strong>: our species is an expert at living in a wide array of environments, with populations culturally specializing in their own particular surroundings. The next section tracks how far around the world these skeletal and behavioural traits have taken us.<\/p>\n<h2 class=\"import-Normal\">First Africa, Then the World<\/h2>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">What enabled modern <em>Homo sapiens<\/em> to expand its range further in 300,000 years than <em>Homo erectus<\/em> did in 1.5 million years? The key is the set of derived biological traits from the last section. It is theorized that the gracile frame and neurological anatomy allowed modern humans to survive and even flourish in the vastly different environments they encountered. Based on multiple types of evidence, the source of all of these modern humans was Africa. Instead of originating from just one location, evidence shows that modern Homo sapiens evolution occurred in a complex gene flow network across Africa, a concept called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1760\">African multiregionalism<\/a><\/strong> (Scerri Et al. 2018).<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">This section traces the origin of modern <em>Homo sapiens<\/em> and the massive expansion of our species across all of the continents (except Antarctica) by 12,000 years ago. While modern <em>Homo sapiens<\/em> first shared geography with archaic humans, modern humans eventually spread into lands where no human had gone before. Figure 13.5 shows the broad routes that our species took expanding around the world. I encourage you to make your own timeline with the dates in this part to see the overall trends.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><img class=\"aligncenter\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image13-6.png\" alt=\"315 to 195 KYA. Northern to eastern coasts of Africa are shaded.\" width=\"554\" height=\"428\" \/><\/p>\n<p class=\"import-Normal\"><img class=\"aligncenter\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image17-5.png\" alt=\"195-100 KYA. Africa, southern Europe and Asia are shaded\" width=\"554\" height=\"428\" \/><\/p>\n<p class=\"import-Normal\"><img class=\"aligncenter\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image27-3.png\" alt=\"99 to 30 KYA. Africa, Indonesia, Australia, and southern portions of Europe and Asia are shaded.\" width=\"554\" height=\"428\" \/><\/p>\n<figure style=\"width: 554px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image30-2.png\" alt=\"29 to 9 KYA. Shading covers most land except Antarctica, Greenland, and some islands.\" width=\"554\" height=\"428\" \/><figcaption class=\"wp-caption-text\">Figure 13.5a-d: Four maps depicting the estimated range of modern Homo sapiens through time. The shaded area is based on geographical connections across known sites. Note the growth in the area starting in Africa and the oftentimes-coastal routes that populations followed. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-14\/\">Four maps depicting the estimated range of modern Homo sapiens through time<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Elyssa Ebding at <a href=\"https:\/\/www.csuchico.edu\/geop\/geoplace\/index.shtml\">GeoPlace, California State University, Chico<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<h3 class=\"import-Normal\"><strong>Modern <\/strong><strong><em>Homo sapiens<\/em><\/strong><strong> Biology and Culture in Africa<\/strong><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">We start with the ample fossil evidence supporting the theory that modern humans originated in Africa during the Middle Pleistocene, having evolved from African archaic <em>Homo sapiens<\/em>. The earliest dated fossils considered to be modern actually have a mosaic of archaic and modern traits, showing the complex changes from one type to the other. Experts have various names for these transitional fossils, such as <strong><strong>Early Modern <\/strong><strong><em>Homo sapiens\u00a0 <\/em><\/strong> or Early Anatomically Modern Humans<\/strong>. However they are labeled, the presence of some modern traits means that they illustrate the origin of the modern type. Three particularly informative sites with fossils of the earliest modern <em>Homo sapiens<\/em> are Jebel Irhoud, Omo, and Herto.<\/p>\n<figure style=\"width: 281px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image9-1-1.jpg\" alt=\"3D image of a human cranium with pronounced brow ridges.\" width=\"281\" height=\"282\" \/><figcaption class=\"wp-caption-text\">Figure 13.6: Composite rendering of the Jebel Irhoud hominin based on micro-CT scans of multiple fossils from the site. The facial structure is within the modern human range, while the braincase is between the archaic and modern shapes. Credit: <a href=\"https:\/\/www.eva.mpg.de\/homo-sapiens\/presskit.html\">A composite reconstruction of the earliest known Homo sapiens fossils from Jebel Irhoud (Morocco) based on micro computed tomographic scans<\/a> by Philipp Gunz, <a href=\"https:\/\/www.eva.mpg.de\/index.html\">MPI EVA Leipzig<\/a>, is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/\">CC BY-SA 2.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Recall from the start of the chapter that the most recent finds at Jebel Irhoud are now the oldest dated fossils that exhibit some facial traits of modern <em>Homo sapiens<\/em>. Besides Irhoud 10, the cranium that was dated to 315,000 years ago (Hublin Et al. 2017; Richter Et al. 2017), there were other fossils found in the same deposit that we now know are from the same time period. In total there are at least five individuals, representing life stages from childhood to adulthood. These fossils form an image of high variation in skeletal traits. For example, the skull named Irhoud 1 has a primitive brow ridge, while Irhoud 2 and Irhoud 10 do not (Figure 13.6). The braincases are lower than what is seen in the modern humans of today but higher than in archaic <em>Homo sapiens<\/em>. The teeth also have a mix of archaic and modern traits that defy clear categorization into either group.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Research separated by nearly four decades uncovered fossils and artifacts from the Kibish Formation in the Lower Omo Valley in Ethiopia. These Omo Kibish hominins were represented by braincases and fragmented postcranial bones of three individuals found kilometres apart, dating back to around 233,000 years ago (Day 1969; McDougall, Brown, and Fleagle 2005; Vidal Et al. 2022). One interesting finding was the variation in braincase size between the two more-complete specimens: while the individual named Omo I had a more globular dome, Omo II had an archaic-style long and low cranium.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Also in Ethiopia, a team led by Tim White (2003) excavated numerous fossils at Herto. There were fossilized crania of two adults and a child, along with fragments of more individuals. The dates ranged between 160,000 and 154,000 years ago. The skeletal traits and stone-tool assemblage were both intermediate between the archaic and modern types. Features reminiscent of modern humans included a tall braincase and thinner zygomatic (cheek) bones than those of archaic humans (Figure 13.7). Still, some archaic traits persisted in the Herto fossils, such as the supraorbital tori. Statistical analysis by other research teams concluded that at least some cranial measurements fit just within the modern human range (McCarthy and Lucas 2014), favouring categorization with our own species.<\/p>\n<figure style=\"width: 373px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image4-3.jpg\" alt=\"Replica cranium showing wide brow ridges and gracile face.\" width=\"373\" height=\"373\" \/><figcaption class=\"wp-caption-text\">Figure 13.7: This model of the Herto cranium showing its mosaic of archaic and modern traits. Credit: <a href=\"https:\/\/boneclones.com\/product\/homo-sapiens-idaltu-bou-vp-16-1-herto-skull-BH-045\/category\/all-fossil-hominids\/fossil-hominids\">Homo sapiens idaltu BOU-VP-16\/1 Herto Cranium<\/a> by <a href=\"https:\/\/boneclones.com\/\">\u00a9BoneClones<\/a> is used by permission and available here under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">The timeline of material culture suggests a long period of relying on similar tools before a noticeable diversification of artifacts types. Researchers label the time of stable technology shared with archaic types the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1766\"><strong>Middle Stone Age<\/strong><\/a>, while the subsequent time of diversification in material culture is called the<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1767\"> <strong>Later Stone Age<\/strong><\/a>.<\/p>\n<p class=\"import-Normal\">In the Middle Stone Age, the sites of Jebel Irhoud, Omo, and Herto all bore tools of the same flaked style as archaic assemblages, even though they were separated by almost 150,000 years. The consistency in technology may be evidence that behavioural modernity was not so developed. No clear signs of art dating back this far have been found either. Other hypotheses not related to behavioural modernity could explain these observations. The tool set may have been suitable for thriving in Africa without further innovation. Maybe works of art from that time were made with media that deteriorated or perhaps such art was removed by later humans.<\/p>\n<p class=\"import-Normal\">Evidence of what <em>Homo sapiens<\/em> did in Africa from the end of the Middle Stone Age to the Later Stone Age is concentrated in South African cave sites that reveal the complexity of human behaviour at the time. For example, Blombos Cave, located along the present shore of the Cape of Africa facing the Indian Ocean, is notable for having a wide variety of artifacts. The material culture shows that toolmaking and artistry were more complex than previously thought for the Middle Stone Age. In a layer dated to 100,000 years ago, researchers found two intact ochre-processing kits made of abalone shells and grinding stones (Henshilwood Et al. 2011). Marine snail shell beads from 75,000 years ago were also excavated (Figure 13.8; d\u2019Errico Et al. 2005). Together, the evidence shows that the Middle Stone Age occupation at Blombos Cave incorporated resources from a variety of local environments into their culture, from caves (ochre), open land (animal bones and fat), and the sea (abalone and snail shells). This complexity shows a deep knowledge of the region\u2019s resources and their use\u2014not just for survival but also for symbolic purposes.<\/p>\n<figure style=\"width: 563px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image5-2-1.jpg\" alt=\"Multiple views of shells with holes bored through them.\" width=\"563\" height=\"482\" \/><figcaption class=\"wp-caption-text\">Figure 13.8: Examples of the perforated shell beads found in Blombos Cave, South Africa: (a) view of carved hole seen from the inside; (b) arrows indicate worn surfaces due to repetitive contact with other objects, such as with other beads or a connecting string; (c) traces of ochre; and (d) four shell beads showing a consistent pattern of perforation. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:BBC-shell-beads.jpg\">BBC-shell-beads<\/a> by Chenshilwood (Chris Henshilbood and Francesco d\u2019Errico) at <a href=\"https:\/\/en.wikipedia.org\/wiki\/\">English Wikipedia<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">On the eastern coast of South Africa, Border Cave shows new African cultural developments at the start of the Later Stone Age. Paola Villa and colleagues (2012) identified several changes in technology around 43,000 years ago. Stone-tool production transitioned from a slower process to one that was faster and made many <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1777\">microliths<\/a><\/strong>, small and precise stone tools. Changes in decorations were also found across the Later Stone Age transition. Beads were made from a new resource: fragments of ostrich eggs shaped into circular forms resembling present-day breakfast cereal O\u2019s (d\u2019Errico Et al. 2012). These beads show a higher level of altering one\u2019s own surroundings and a move from the natural to the abstract in terms of design.<\/p>\n<h3 class=\"import-Normal\"><strong>Expansion into the Middle East and Asia<\/strong><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">While modern <em>Homo sapiens<\/em> lived across Africa, some members eventually left the continent. These pioneers could have used two connections to the Middle East or West Asia. From North Africa, they could have crossed the Sinai Peninsula and moved north to the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1769\"><strong>Levant<\/strong><\/a>, or eastern Mediterranean. Finds in that region show an early modern human presence. Other finds support the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1770\">Southern Dispersal model<\/a><\/strong>, with a crossing from East Africa to the southern Arabian Peninsula through the Straits of Bab-el-Mandeb. It is tempting to think of one momentous event in which people stepped off Africa and into the Middle East, never to look back. In reality, there were likely multiple waves of movement producing gene flow back and forth across these regions as the overall range pushed east. The expanding modern human population could have thrived by using resources along the southern coast of the Arabian Peninsula to South Asia, with side routes moving north along rivers. The maximum range of the species then grew across Asia.<\/p>\n<h4 class=\"import-Normal\"><em>Modern <\/em>Homo sapiens<em> in the Middle East<\/em><\/h4>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Geographically, the Middle East is the ideal place for the African modern <em>Homo sapiens<\/em> population to inhabit upon expanding out of their home continent. In the Eastern Mediterranean coast of the Levant, there is a wealth of skeletal and material culture linked to modern <em>Homo sapiens<\/em>. Recent discoveries from Saudi Arabia further add to our view of human life just beyond Africa.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The Caves of Mount Carmel in present-day Israel have preserved skeletal remains and artifacts of modern <em>Homo sapiens<\/em>, the first-known group living outside Africa. The skeletal presence at Misliya Cave is represented by just part of the left upper jaw of one individual, but it is notable for being dated to a very early time, between 194,000 and 177,000 years ago (Hershkovitz Et al. 2018). Later, from 120,000 to 90,000 years ago, fossils of multiple individuals across life stages were found in the caves of Es-Skhul and Qafzeh (Shea and Bar-Yosef 2005). The skeletons had many modern <em>Homo sapiens<\/em> traits, such as globular crania and more gracile postcranial bones when compared to Neanderthals. Still, there were some archaic traits. For example, the adult male Skhul V also possessed what researchers Daniel Lieberman, Osbjorn Pearson, and Kenneth Mowbray (2000) called marked or clear occipital bunning. Also, compared to later modern humans, the Mount Carmel people were more robust. Skhul V had a particularly impressive brow ridge that was short in height but sharply jutted forward above the eyes (Figure 13.9). The high level of preservation is due to the intentional burial of some of these people. Besides skeletal material, there are signs of artistic or symbolic behaviour. For example, the adult male Skhul V had a boar\u2019s jaw on his chest. Similarly, Qafzeh 11, a juvenile with healed cranial trauma, had an impressive deer antler rack placed over his torso (Figure 13.10; Coqueugniot Et al. 2014). Perforated seashells coloured with <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1806\"><strong>ochre<\/strong><\/a>, mineral-based pigment, were also found in Qafzeh (Bar-Yosef Mayer, Vandermeersch, and Bar-Yosef 2009).<\/p>\n<p>&nbsp;<\/p>\n<figure style=\"width: 484px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image6-2-1.jpg\" alt=\"Side view of a skull replica with a globular braincase.\" width=\"484\" height=\"484\" \/><figcaption class=\"wp-caption-text\">Figure 13.9: This Skhul V cranium model shows the sharp browridges. The contour of a marked occipital bun is barely visible from this angle. Credit: <a href=\"https:\/\/boneclones.com\/product\/homo-sapiens-skull-skhul-5-BH-032\">Homo sapiens Skull Skhul 5<\/a> by <a href=\"https:\/\/boneclones.com\/\">\u00a9BoneClones<\/a> is used by permission and available here under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<figure style=\"width: 484px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image26-1-1.jpg\" alt=\"Human skeleton in a stony matrix. Ribs are visible below the antlers.\" width=\"484\" height=\"312\" \/><figcaption class=\"wp-caption-text\">Figure 13.10 This cast of the Qafzeh 11 burial shows the antler\u2019s placement over the upper torso. The forearm bones appear to overlap the antler. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Moulage_de_la_s%C3%A9pulture_de_l&apos;individu_%22Qafzeh_11%22_(avec_ramure_de_cervid%C3%A9),_homme_de_N%C3%A9andertal.jpg\">Moulage de la s\u00e9pulture de l'individu \"Qafzeh 11\" (avec ramure de cervid\u00e9), homme de N\u00e9andertal<\/a> (Collections du Mus\u00e9um national d'histoire naturelle de Paris, France) by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Eunostos\">Eunostos<\/a> has been modified (cropped and colour modified) and is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">One remaining question is, what happened to the modern humans of the Levant after 90,000 years ago? Another site attributed to our species did not appear in the region until 47,000 years ago. Competition with Neanderthals may have accounted for the disappearance of modern human occupation since the Neanderthal presence in the Levant lasted longer than the dates of the early modern <em>Homo sapiens<\/em>. John Shea and Ofer Bar-Yosef (2005) hypothesized that the Mount Carmel modern humans were an initial expansion from Africa that failed. Perhaps they could not succeed due to competition with the Neanderthals who had been there longer and had both cultural and biological adaptations to that environment.<\/p>\n<h4 class=\"import-Normal\"><em>Modern <\/em>Homo sapiens<em> of China<\/em><\/h4>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">A long history of paleoanthropology in China has found ample evidence of modern human presence. Four notable sites are the caves at Fuyan, Liujiang, Tianyuan, and Zhoukoudian. In the distant past, these caves would have been at least seasonal shelters that unintentionally preserved evidence of human presence for modern researchers to discover.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">At Fuyan Cave in Southern China, paleoanthropologists found 47 adult teeth associated with cave formations dated to between 120,000 and 80,000 years ago (Liu Et al. 2015). It is currently the oldest-known modern human site in China, though other researchers question the validity of the date range (Michel Et al. 2016). The teeth have the small size and gracile features of modern <em>Homo sapiens<\/em> dentition.<\/p>\n<p class=\"import-Normal\">The fossil Liujiang (or Liukiang) hominin (67,000 years ago) has derived traits that classified it as a modern <em>Homo sapiens<\/em>, though primitive archaic traits were also present. In the skull, which was found nearly complete, the Liujiang hominin had a taller forehead than archaic <em>Homo sapiens<\/em> but also had an enlarged occipital region (Figure 13.11; Brown 1999; Wu Et al. 2008). Other parts of the skeleton also had a mix of modern and archaic traits: for example, the femur fragments suggested a slender length but with thick bone walls (Woo 1959).<\/p>\n<p>&nbsp;<\/p>\n<figure style=\"width: 486px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image19-1-2.jpg\" alt=\"A human skull with very slight brow ridges and an extremely globular braincase.\" width=\"486\" height=\"323\" \/><figcaption class=\"wp-caption-text\">Figure 13.11: The Liujiang cranium shows the tall forehead and overall gracile appearance typical of modern Homo sapiens. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Liujiang_cave_skull-a._Homo_Sapiens_68,000_Years_Old.jpg\">Liujiang cave skull-a. Homo Sapiens 68,000 Years Old<\/a> (Taken at the David H. Koch Hall of Human Origins, <a href=\"https:\/\/naturalhistory.si.edu\/visit\">Smithsonian Natural History Museum<\/a>) by <a href=\"https:\/\/www.flickr.com\/people\/14405058@N08\">Ryan Somma<\/a> has been modified (colour modified) and is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\">CC BY-SA 2.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Another Chinese site to describe here is the one that has been studied the longest. In the Zhoukoudian Cave system (Figure 13.12), where <em>Homo erectus<\/em> and archaic <em>Homo sapiens<\/em> have also been found, there were three crania of modern <em>Homo sapiens<\/em>. These crania, which date to between 34,000 and 10,000 years ago, were all more globular than those of archaic humans but still lower and longer than those of later modern humans (Brown 1999; Harvati 2009). When compared to one another, the crania showed significant differences from one another. Comparison of cranial measurements to other populations past and present found no connection with modern East Asians, again showing that human variation was very different from what we see today.<\/p>\n<p>&nbsp;<\/p>\n<figure style=\"width: 610px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image12-1.jpg\" alt=\"A cave opening amongst a dry wooded region.\" width=\"610\" height=\"458\" \/><figcaption class=\"wp-caption-text\">Figure 13.12: The entrance to the Upper Cave of the Zhoukoudian complex, where crania of three ancient modern humans were found. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Zhoukoudian_Upper_Cave.jpg\">Zhoukoudian Upper Cave<\/a> by Mutt is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<h3 class=\"import-Normal\"><strong>Crossing to Australia<\/strong><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Expansion of the first modern human Asians, still following the coast, eventually entered an area that researchers call <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1772\">Sunda<\/a><\/strong> before continuing on to modern Australia. Sunda was a landmass made up of the modern-day Malay Peninsula, Sumatra, Java, and Borneo. Lowered sea levels connected these places with land bridges, making them easier to traverse. Proceeding past Sunda meant navigating <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1773\">Wallacea<\/a><\/strong>, the archipelago that includes the Indonesian islands east of Borneo. In the distant past, there were many <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_864\">megafauna<\/a><\/strong>, large animals that migrating humans would have used for food and materials (such as utilizing animals\u2019 hides and bones). Further southeast was another landmass called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1774\">Sahul<\/a><\/strong>, which included New Guinea and Australia as one contiguous continent. Based on fossil evidence, this land had never seen hominins or any other primates before modern <em>Homo sapiens<\/em> arrived. Sites along this path offer clues about how our species handled the new environment to live successfully as foragers.<\/p>\n<figure style=\"width: 380px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image18-1-1.jpg\" alt=\"A cranium showing a diagonal sloping forehead.\" width=\"380\" height=\"252\" \/><figcaption class=\"wp-caption-text\">Figure 13.13: Replica of the Kow Swamp 1 cranium. The shape of the braincase could be due to artificial cranial modification. A competing hypothesis is that it reflects the primitive shape of Homo erectus. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Kow_Swamp1-Homo_sapiens.jpg\">Kow Swamp1-Homo sapiens<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/14405058@N08\">Ryan Somma<\/a> from Occoquan, USA, under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\">CC BY-SA 2.0 License<\/a> has been modified (background cleaned and colour modified) and is available here under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The skeletal remains at Lake Mungo, land traditionally owned by Mutthi Mutthi, Ngiampaa, and Paakantji peoples, are the oldest known in the continent. The now-dry lake was one of a series located along the southern coast of Australia in New South Wales, far from where the first people entered from the north (Barbetti and Allen 1972; Bowler Et al. 1970). Two individuals dating to around 40,000 years ago show signs of artistic and symbolic behaviour, including intentional burial. The bones of Lake Mungo 1 (LM1), an adult female, were crushed repeatedly, coloured with red ochre, and cremated (Bowler Et al. 1970). Lake Mungo 3 (LM3), a tall, older male with a gracile cranium but robust postcranial bones, had his fingers interlocked over his pelvic region (Brown 2000).<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Kow Swamp, within traditional Yorta Yorta land also in southern Australia, contained human crania that looked distinctly different from the ones at Lake Mungo (Durband 2014; Thorne and Macumber 1972). The crania, dated between 9,000 and 20,000 years ago, had extremely robust brow ridges and thick bone walls, but these were paired with globular features on the braincase (Figure 13.13).<\/p>\n<p class=\"import-Normal\">While no fossil humans have been found at the Madjedbebe rock shelter in the North Territory of Australia, more than 10,000 artifacts found there show both behavioural modernity and variability (Clarkson Et al. 2017). They include a diverse array of stone tools and different shades of ochre for rock art, including mica-based reflective pigment (similar to glitter). These impressive artifacts are as far back as 56,000 years old, providing the date for the earliest-known presence of humans in Australia.<\/p>\n<h3 class=\"import-Normal\"><strong>From the Levant to Europe<\/strong><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The first modern human expansion into Europe occurred after other members of our species settled in East Asia and Australia. As the evidence from the Levant suggests, modern human movement to Europe may have been hampered by the presence of Neanderthals. <span style=\"margin: 0px;padding: 0px\">It is suggested that another obstacle was the colder climate, which was incompatible with the biology of modern <em>Homo sapiens<\/em> from Africa, as they were adapted to high temperatures and ultraviolet radiation.<\/span> Still, by 40,000 years ago, modern <em>Homo sapiens<\/em> had a detectable presence. This time was also the start of the Later Stone Age or <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1775\">Upper Paleolithic<\/a><\/strong>, when there was an expansion in cultural complexity. There is a wealth of evidence from this region due to a Western bias in research, the proximity of these findings to Western scientific institutions, and the desire of Western scientists to explore their own past.<\/p>\n<figure style=\"width: 323px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image11-3.jpg\" alt=\"Robust cranium with a gradually sloping forehead.\" width=\"323\" height=\"323\" \/><figcaption class=\"wp-caption-text\">Figure 13.14: This side view of the Oase 2 cranium shows the reduced brow ridges but also occipital bunning that is a sign that modern Homo sapiens interbred with Neanderthals. Credit: <a href=\"https:\/\/humanorigins.si.edu\/evidence\/human-fossils\/fossils\/oase-2\">Oase 2<\/a> by James Di Loreto &amp; Donald H. Hurlbert, <a href=\"https:\/\/www.si.edu\/\">Smithsonian<\/a> [exhibit: Human Evolution Evidence, Human Fossils] has been modified (sharpened) and <a href=\"https:\/\/www.si.edu\/termsofuse\">is used for educational and non-commercial purposes as outlined by the Smithsonian.<\/a><\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">In Romania, the site of Pe\u0219tera cu Oase (Cave of Bones) had the oldest-known remains of modern <em>Homo sapiens<\/em> in Europe, dated to around 40,000 years ago (Trinkaus Et al. 2003a). Among the bones and teeth of many animals were the fragmented cranium of one person and the mandible of another (the two bones did not fit each other). Both bones have modern human traits similar to the fossils from the Middle East, but they also had Neanderthal traits. Oase 1, the mandible, had a mental eminence but also extremely large molars (Trinkaus Et al. 2003b). This mandible has yielded DNA that surprisingly is equally similar to DNA from present-day Europeans and Asians (Fu Et al. 2015). This means that Oase 1 was not the direct ancestor of modern Europeans. The Oase 2 cranium has the derived traits of reduced brow ridges along with archaic wide zygomatic cheekbones and an occipital bun (Figure 13.14; Rougier Et al. 2007).<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Dating to around 26,000 years ago, P\u0159edmost\u00ed near P\u0159erov in the Czech Republic was a site where people buried over 30 individuals along with many artifacts. Eighteen individuals were found in one mass burial area, a few covered by the scapulae of woolly mammoths (Germonpr\u00e9, L\u00e1zni\u010dkov\u00e1-Galetov\u00e1, and Sablin 2012). The P\u0159edmost\u00ed crania were more globular than those of archaic humans but tended to be longer and lower than in later modern humans (Figure 13.15; Velem\u00ednsk\u00e1 Et al. 2008). The height of the face was in line with modern residents of Central Europe. There was also skeletal evidence of dog domestication, such as the presence of dog skulls with shorter snouts than in wild wolves (Germonpr\u00e9, L\u00e1zni\u010dkov\u00e1-Galetov\u00e1, and Sablin Et al. 2012). In total, P\u0159edmost\u00ed could have been a settlement dependent on mammoths for subsistence and the artificial selection of early domesticated dogs.<\/p>\n<figure style=\"width: 423px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image25-3.png\" alt=\"Black-and-white photograph of a human skull with labeled cranial landmarks.\" width=\"423\" height=\"389\" \/><figcaption class=\"wp-caption-text\">Figure 13.15: This illustration is based upon one of the surviving photographic negatives since the original fossil was lost in World War II. The modern human chin is prominent, as is an archaic occipital bun. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:P%C5%99edmost%C3%AD_9.png\">P\u0159edmost\u00ed 9<\/a> by J. Matiegka (1862\u20131941) has been modified (sharpened) and is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\">public domain<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The sequence of modern <em>Homo sapiens<\/em> technological change in the Later Stone Age has been thoroughly dated and labeled by researchers working in Europe. Among them, the Gravettian tradition of 33,000 years to 21,000 years ago is associated with most of the known curvy female figurines, often assumed to be \u201cVenus\u201d figures. Hunting technology also advanced in this time with the first known boomerang, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1792\"><strong>atlatl<\/strong><\/a> (spear thrower), and archery. The Magdalenian tradition spread from 17,000 to 12,000 years ago. This culture further expanded on fine bone tool work, including barbed spearheads and fishhooks (Figure 13.16).<\/p>\n<figure style=\"width: 511px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image2-1-1.jpg\" alt=\"Long, thin spear tips. Many have barbs, others are smooth.\" width=\"511\" height=\"494\" \/><figcaption class=\"wp-caption-text\">Figure 13.16: This drawing from 1891 shows an array of Magdalenian-style barbed points found in the burial of a reindeer hunter. They were carved from antler. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:La_station_quaternaire_de_Raymonden_(...)Hardy_Michel_bpt6k5567846s_(2).jpg\">La station quaternaire de Raymonden (...)Hardy Michel bpt6k5567846s (2)<\/a> by M. F\u00e9auxis, original by Michel Hardy (1891), is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\">public domain<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Among the many European sites dating to the Later Stone Age, the famous cave art sites deserve mention. Chauvet-Pont-d'Arc Cave in southern France dates to separate Aurignacian occupations 31,000 years ago and 26,000 years ago. Over a hundred art pieces representing 13 animal species are preserved, from commonly depicted deer and horses to rarer rhinos and owls. Another French cave with art is Lascaux, which is several thousand years younger at 17,000 years ago in the Magdalenian period. At this site, there are over 6,000 painted figures on the walls and ceiling (Figure 13.17). Scaffolding and lighting must have been used to make the paintings on the walls and ceiling deep in the cave. Overall, visiting Lascaux as a contemporary must have been an awesome experience: trekking deeper in the cave lit only by torches giving glimpses of animals all around as mysterious sounds echoed through the galleries.<\/p>\n<p>&nbsp;<\/p>\n<figure style=\"width: 605px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image24-2-1.jpg\" alt=\"Charcoal painting of a bull seen from the side.\" width=\"605\" height=\"454\" \/><figcaption class=\"wp-caption-text\">Figure 13.17: Photograph of just one surface with cave art at Lascaux Cave. The most prominent piece here is the Second Bull, found in a chamber called the Hall of Bulls. Smaller cattle and horses are also visible. Credit: <a href=\"https:\/\/whc.unesco.org\/en\/documents\/108435\">Lascaux cave (document 108435) Prehitoric Sites and Decorated Caves of the V\u00e9z\u00e8re Valley (France)<\/a> by Francesco Bandarin, <a href=\"https:\/\/whc.unesco.org\/\">\u00a9 UNESCO<\/a>, has been modified (colour modified) and is under a <a href=\"https:\/\/whc.unesco.org\/en\/licenses\/6\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<div class=\"textbox shaded\" style=\"background: var(--lightblue)\">\n<h2>Special Topic: Cannibalism and Culture - Mortuary Practices in Modern Homo sapiens<\/h2>\n<p>Within a 2017 publication in the <em>Journal of Archaeological Method and Theory<\/em>, Saladi\u00e9 and Rodr\u00edguez-Hidalgo bring light to traces of early cannibalism in western Eurasia, arguing that context-specific cannibalistic practices were present throughout the Pleistocene and increased notably from the end of the Upper Palaeolithic and onward (Saladi\u00e9 &amp; Rodriguez-Hidalgo, 2017). While early hominins and Neandertals are recognized in this research, the authors highlight the presence of these mortuary practices in a cluster of <em>Homo sapiens<\/em> sites. More recent research uncovers similar findings that back these claims as well, where human bones in Herto Ethiopia, Maszycka Cave Poland, and Gough\u2019s Cave in the United Kingdom show anthropogenic defleshing and other modifications which have been interpreted as cannibalism (Pobiner, Et al. 2023). These findings suggest that cannibalistic behaviours formed a recurring aspect of modern human behaviour in certain ecological and cultural contexts.<\/p>\n<figure id=\"attachment_817\" aria-describedby=\"caption-attachment-817\" style=\"width: 378px\" class=\"wp-caption alignleft\"><img class=\" wp-image-817\" src=\"http:\/\/opentextbooks.concordia.ca\/explorationsversiontwo\/wp-content\/uploads\/sites\/71\/2023\/06\/d_-_briana_pobiner_-_figure_6.jpg\" alt=\"\" width=\"378\" height=\"369\" \/><figcaption id=\"caption-attachment-817\" class=\"wp-caption-text\">Figure 13.18: Close-up photos of three fossil animal specimens from the same area and time horizon as the fossil hominin tibia studied by the research team. These fossils show similar cut marks to those found on the hominin tibia studied. The photos show (a) an antelope mandible, (b) an antelope radius (lower front leg bone) and (c) a large mammal scapula (shoulder blade). Credit: <em data-start=\"617\" data-end=\"635\">23-199D Figure 6<\/em> by Smithsonian\u2019s National Museum of Natural History, from \"<a href=\"https:\/\/www.si.edu\/newsdesk\/releases\/humans-evolutionary-relatives-butchered-one-another-145-million-years-ago\">Humans\u2019 Evolutionary Relatives Butchered One Another 1.45 Million Years Ago<\/a>,\" \u00a9 Smithsonian Institution, used with permission.<\/figcaption><\/figure>\n<p>A significant example comes from the Neolithic levels of Fontbr\u00e9gua Cave in southeastern France, where Paola Villa and colleagues compared clusters of human bones with the remains of wild and domestic animals from the same sediments. The study found that human bodies were butchered, processed, and most likely eaten in a way that parallels animal carcass treatment, including the placement and timing of cut marks, dismemberment sequences, and perimortem fractures to open marrow cavities (Villa, Et al. 1986). As the assemblage comes from a primary depositional context with pristine preservation and careful excavation, the authors suggest that cannibalism is the only satisfactory explanation for the pattern of cut marks and breakage seen on the human bones.<\/p>\n<p>More recent work has furthered this hypothesis for Late Upper Palaeolithic <em>Homo sapiens<\/em>, especially in Magdalenian contexts. In a 2023 study, researchers combined archeological and genetic evidence from fifty-nine Magdalenian sites, concluding that this specific culture shows an unusually high frequency of cannibalistic cases compared to earlier and later hominin groups; so much so that they identify \u201cprimary burial and cannibalism\u201d as the two main mortuary expressions (Marsh &amp; Bello, 2023). Additionally, new analyses from Maszycka Cave in Poland have described cut and broken human bones in patterns consistent with human consumption, reinforcing this cannibalism hypothesis (Marginedas &amp; Saladi\u00e9, 2025). Together, these studies suggest that for some Magdalenian groups, mortuary cannibalism was a habitual way of disposing of the dead, not just a one-off crisis response. At the same time, researchers emphasize that not every modified skeleton indicates blatant consumption of the dead and that ritual or symbolic perspectives must also be considered. Previously noted in chapter 12, Ullrich\u2019s survey of European mortuary practices presents frequent manipulations of corpses from the Palaeolithic through the Hallstatt period. Said manipulations include cut marks, dismemberment, skull fracturing, and marrow extraction (Ullrich, 2005, p. 258), which Ullrich interprets as cannibalistic rites embedded in cult ceremonies rather than everyday subsistence. In the author\u2019s view, some Palaeolithic groups may have believed that consuming members of their community allowed them to take on the strengths,<\/p>\n<figure id=\"attachment_819\" aria-describedby=\"caption-attachment-819\" style=\"width: 265px\" class=\"wp-caption alignright\"><img class=\"wp-image-819\" src=\"http:\/\/opentextbooks.concordia.ca\/explorationsversiontwo\/wp-content\/uploads\/sites\/71\/2023\/06\/a_-_briana_pobiner_-_figure_1.jpg\" alt=\"\" width=\"265\" height=\"379\" \/><figcaption id=\"caption-attachment-819\" class=\"wp-caption-text\">Figure 13.19: View of the hominin tibia and magnified area that shows cut marks. Scale = 4 cm. Credit: 23-199A Figure 1 by Jennifer Clark, Smithsonian Institution, from \"<a href=\"https:\/\/www.si.edu\/newsdesk\/releases\/humans-evolutionary-relatives-butchered-one-another-145-million-years-ago\">Humans\u2019 Evolutionary Relatives Butchered One Another 1.45 Million Years Ago<\/a>,\" \u00a9Smithsonian Institution, used with permission.<\/figcaption><\/figure>\n<p>abilities, or even mental aspects of their dead member; the act of cannibalism may have functioned as a form of appropriating physical and mental powers rather than simply obtaining calories. With that, Neolithic assemblages show how careful taphonomic work can distinguish cuts linked to interpersonal violence from those associated with systemic butchery (Marginedas &amp; Saladi\u00e9, 2025). The findings seek to highlight that some <em>Homo sapiens<\/em> populations combined ritual, mortuary, and nutritional motives when processing human remains.<\/p>\n<p>These past and contemporary findings are significant for future anthropology students as they shed light on biological anthropology methodology and interpretation. Archaeologists are able to distinguish between occasions when humans were handled like any other carcass and times when they were handled in more symbolic ways thanks to factors like cut mark orientation, the timing of bone breakage, and direct comparison with animal remains. Readers interested in exploring this topic further should investigate the context-specific motivations for cannibalism, like nutritional stress, warfare, funerary sites, or ritual power appropriation.<\/p>\n<p>Similar archeological techniques have been used to explore behaviours of cannibalism among Indigenous Huron-Wendat populations in 1651 Canada, where human bones exhibit cutmarks, perimortem fractures, and thermal modifications (Spence &amp; Jackson, 2014). These shared taphonomic signatures across continents reveal recurring practices under ecological stress, bridging prehistoric Europe to North American contexts. Engaging with such analytical techniques opens up new ways that archeologists and anthropologists can investigate the variability in human behaviour, from nutritional crises to mortuary rituals.<\/p>\n<\/div>\n<h3 class=\"import-Normal\"><strong>Peopling of the Americas<\/strong><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">By 25,000 years ago, our species was the only member of <em>Homo<\/em> left on Earth. Gone were the Neanderthals, Denisovans, <em>Homo naledi,<\/em> and <em>Homo floresiensis<\/em>. The range of modern <em>Homo sapiens<\/em> kept expanding eastward into\u2014using the name given to this area by Europeans much later\u2014the Western Hemisphere. This section will address what we know about the peopling of the Americas, from the first entry to these continents to the rapid spread of Indigenous Americans across its varied environments.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">While evidence points to an ancient land bridge called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1778\"><strong>Beringia<\/strong><\/a> that allowed people to cross from what is now northeastern Siberia into modern-day Alaska, what people did to cross this land bridge is still being investigated. For most of the 20th century, the accepted theory was the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1779\"><strong>Ice-Free Corridor model<\/strong><\/a>. It stated that northeast Asians (East Asians and Siberians) first expanded across Beringia inland through a passage between glaciers that opened into the western Great Plains of the United States, just east of the Rocky Mountains, around 13,000 years ago (Swisher Et al. 2013). While life up north in the cold environment would have been harsh, migrating birds and an emerging forest might have provided sustenance as generations expanded through this land (Potter Et al. 2018).<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">However, in recent decades, researchers have accumulated evidence against the Ice-Free Corridor model. Archaeologist K. R. Fladmark (1979) brought the alternate <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1780\"><strong>Coastal Route model<\/strong><\/a> into the archaeological spotlight; researcher Jon M. Erlandson has been at the forefront of compiling support for this theory (Erlandson Et al. 2015). The new focus is the southern edge of the land bridge instead of its centre: About 16,000 years ago, members of our species expanded along the coastline from northeast Asia, east through Beringia, and south down the Pacific Coast of North America while the inland was still sealed off by ice. The coast would have been free of ice at least part of the year, and many resources would have been found there, such as fish (e.g., salmon), mammals (e.g., whales, seals, and otters), and plants (e.g., seaweed).<\/p>\n<h4 class=\"import-Normal\"><em>South through the Americas<\/em><\/h4>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">When the first modern <em>Homo sapiens<\/em> reached the Western Hemisphere, the spread through the Americas was rapid. Multiple migration waves crossed from North to South America (Posth Et al. 2018). Our species took advantage of the lack of hominin competition and the bountiful resources both along the coasts and inland. The Americas had their own wide array of megafauna, which included woolly mammoths (Figure 13.20), mastodons, camels, horses, ground sloths, giant tortoises, and\u2014a favourite of researchers\u2014a two-metre-tall beaver. The reason we cannot see these amazing animals today may be that resources gained from these fauna were crucial to the survival for people over 12,000 years ago (Araujo Et al. 2017). Several sites are notable for what they add to our understanding of the distant past in the Americas, including interactions with megafauna and other elements of the environment.<\/p>\n<figure style=\"width: 242px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image3-2-1.jpg\" alt=\"A mammoth model with long curving tusks.\" width=\"242\" height=\"323\" \/><figcaption class=\"wp-caption-text\">Figure 13.20: Life-size reconstruction of a woolly mammoth at the Page Museum, part of the La Brea Tar Pits complex in Los Angeles, California. Outside of Africa, megafauna such as this went extinct around the time that humans entered their range. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-14\/\">Woolly Mammoth<\/a> (at <a href=\"https:\/\/tarpits.org\/\">La Brea Tar Pits &amp; Museum<\/a>) by Keith Chan is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">A 2019 discovery may allow researchers to improve theories about the peopling of the Americas. In White Sands National Park, New Mexico, 60 human footprints have been astonishingly dated to around 22,000 years ago (Bennett Et al. 2021). This date and location do not match either the Ice-Free Corridor or Coastal Route models. Researchers are now working to verify the find and adjust previous models to account for the new evidence. This groundbreaking find is sparking new theories; it is another example of the fast pace of research performed on our past.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Monte Verde is a landmark site that shows that the human population had expanded down the whole vertical stretch of the Americas to Chile by 14,600 years ago. The site has been excavated by archaeologist Tom D. Dillehay and his team (2015). The remains of nine distinct edible species of seaweed at the site shows familiarity with coastal resources and relates to the Coastal Route model by showing a connection between the inland people and the sea.<\/p>\n<figure style=\"width: 254px\" class=\"wp-caption alignright\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image21-4.png\" alt=\"A long stone point with small chips around the edge.\" width=\"254\" height=\"362\" \/><figcaption class=\"wp-caption-text\">Figure 13.21: The Clovis point has a distinctive structure. It has a wide tip, and its base has two small projections. This example was carved from chert and found in north-central Ohio, dated to around 11,000 years ago. Credit: <a href=\"https:\/\/www.si.edu\/object\/chndm_15.2012.25\">Clovis Point<\/a> (15.2012.25) by <a href=\"https:\/\/www.si.edu\/\">the Smithsonian<\/a> [Department of Anthropology; Cooper Hewitt, Smithsonian Design Museum] <a href=\"https:\/\/www.si.edu\/termsofuse\">is used for educational and non-commercial purposes as outlined by the Smithsonian.<\/a><\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Named after the town in New Mexico, the Clovis stone-tool style is the first example of a widespread culture across much of North America, between 13,400 and 12,700 years ago (Miller, Holliday, and Bright 2013). Clovis points were fluted with two small projections, one on each end of the base, facing away from the head (Figure 13.21). The stone points found at this site match those found as far as the Canadian border and northern Mexico, and from the west coast to the east coast of the United States. Fourteen Clovis sites also contained the remains of mammoths or mastodons, suggesting that hunting megafauna with these points was an important part of life for the Clovis people. After the spread of the Clovis style, it diversified into several regional styles, keeping some of the Clovis form but also developing their own unique touches.<\/p>\n<h3 class=\"import-Normal\"><strong>The Big Picture: The Assimilation Hypothesis<\/strong><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">How do researchers make sense of all of these modern <em>Homo sapiens<\/em> discoveries that cover over 300,000 years of time and stretch across every continent except Antarctica? How was modern <em>Homo sapiens<\/em> related to archaic <em>Homo sapiens<\/em>?<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1782\">Assimilation hypothesis<\/a><\/strong> proposes that modern <em>Homo sapiens<\/em> evolved in Africa first and expanded out but also interbred with the archaic <em>Homo sapiens<\/em> they encountered outside Africa (Figure 13.22). This hypothesis is powerful since it explains why Africa has the oldest modern human fossils, why early modern humans found in Europe and Asia bear a resemblance to the regional archaics, and why traces of archaic DNA can be found in our genomes today (Dannemann and Racimo 2018; Reich Et al. 2010; Reich Et al. 2011; Slatkin and Racimo 2016; Smith Et al. 2017; Wall and Yoshihara Caldeira Brandt 2016).<\/p>\n<figure style=\"width: 443px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image28-2.png\" alt=\"African Homo erectus expands and gives rise to archaics and modern Homo sapiens groups.\" width=\"443\" height=\"471\" \/><figcaption class=\"wp-caption-text\">Figure 13.22: This diagram shows archaic humans, having evolved from Homo erectus, expanded from Africa and established the Neanderthal and Denisovan groups. In Africa, archaic humans evolved modern traits and expanded from the continent as well, interbreeding with two archaic groups across Europe and Asia. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-14\/\">Assimilation Model (Figure 12.23)l<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Keith Chan and Katie Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">While researchers have produced a model that satisfies the data, there are still a lot of questions for paleoanthropologists to answer regarding our origins. What were the patterns of migration in each part of the world? Why did the archaic humans go extinct? In what ways did archaic and modern humans interact? The definitive explanation of how our species started and what our ancestors did is still out there to be found. You are now in a great place to welcome the next discovery about our distant past\u2014maybe you\u2019ll even contribute to our understanding as well.<\/p>\n<h2 class=\"import-Normal\">The Chain Reaction of Agriculture<\/h2>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">While it may be hard to imagine today, for most of our species\u2019 existence we were nomadic: moving through the landscape without a singular home. Instead of a refrigerator or pantry stocked with food, we procured nutrition and other resources as needed based on what was available in the environment. This section gives an overview of how the foraging lifestyle enabled the expansion of our species and how the invention of a new way of life caused a chain reaction of cultural change.<\/p>\n<h3 class=\"import-Normal\"><strong>The Foraging Tradition<\/strong><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">There are a variety of possible <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1783\">subsistence strategies<\/a><\/strong>, or methods of finding sustenance and resources. To understand our species is to understand the subsistence strategy of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1114\">foraging<\/a><\/strong>, or the search for resources in the environment. While most (but not all) humans today live in cultures that practice <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1784\">agriculture<\/a> <\/strong>(whereby we greatly shape the environment to mass produce what we need), we have spent far more time as nomadic foragers than as settled agriculturalists. As such, it has been suggested that our traits have evolved to be primarily geared toward foraging. For instance, our efficient bipedalism allows persistence-hunting across long distances as well as movement from resource to resource.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">How does human foraging, also known as hunting and gathering, work? Anthropologists have used all four fields to answer this question (see Ember n.d.). Typically, people formed <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1785\"><strong>bands<\/strong><\/a>, or kin-based groups of around 50 people or less (rarely over 100). A band\u2019s organization would be <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1786\"><strong>e<\/strong><strong>galitarian<\/strong><\/a>, with a flexible hierarchy based on an individual\u2019s age, level of experience, and relationship with others. Everyone would have a general knowledge of the skills assigned to their gender roles, rather than specializing in different occupations. A band would be able to move from place to place in the environment, using knowledge of the area to forage (Figure 13.23). In varied environments\u2014from savannas to tropical forests, deserts, coasts, and the Arctic circle\u2014people found sustenance needed for survival.<\/p>\n<p>&nbsp;<\/p>\n<figure style=\"width: 565px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image22.jpg\" alt=\"A hunter holding a bow is crouched among dry grass.\" width=\"565\" height=\"377\" \/><figcaption class=\"wp-caption-text\">Figure 13.23: A present-day San man in Namibia demonstrates hunting using archery. Anthropologists study the San today to learn about the persistence of foraging as a viable lifestyle, while noting how these cultures have changed over time and how they interact with other groups. Credit: <a href=\"https:\/\/www.flickr.com\/photos\/charlesfred\/2129551464\">San hunter w\u0131th bow and arrow<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/charlesfred\/\">CharlesFred<\/a> has been modified (colour modified) and is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\">CC BY-NC-SA 2.0 License.<\/a><\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Humans made extensive use of the foraging subsistence strategy, but this lifestyle did have limitations. The ease of foraging depended on the richness of the environment. Due to the lack of storage, resources had to be dependably found when needed. While a bountiful environment would require just a few hours of foraging a day and could lead to a focus on one location, the level and duration of labour increased greatly in poor or unreliable environments. Labour was also needed to process the acquired resources, which contributed to the foragers\u2019 daily schedule (Crittenden and Schnorr 2017).<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The adaptations to foraging found in modern <em>Homo sapiens<\/em> may explain why our species became so successful both within Africa and in the rapid expansion around the world. Overcoming the limitations, each generation at the edge of our species\u2019s range would have found it beneficial to expand a little further, keeping contact with other bands but moving into unexplored territory where resources were more plentiful. The cumulative effect would have been the spread of modern <em>Homo sapiens<\/em> across continents and hemispheres.<\/p>\n<h2 class=\"import-Normal\"><strong>Why Agriculture?<\/strong><\/h2>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">After hundreds of thousands of years of foraging, some groups of people around 12,000 years ago started to practice agriculture. This transition, called the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1787\"><strong>Neolithic Revolution<\/strong>,<\/a> occurred at the start of the <strong>Holocene<\/strong> epoch. While the reasons for this global change are still being investigated, two likely co-occurring causes are a growing human population and natural global climate change.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Overcrowding could have affected the success of foraging in the environment, leading to the development of a more productive subsistence strategy (Cohen 1977). Foraging works best with low population densities since each band needs a lot of space to support itself. If too many people occupy the same environment, they deplete the area faster. The high population could exceed the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1788\">carrying capacity<\/a><\/strong>, or number of people a location can reliably support. Reaching carrying capacity on a global level due to growing population and limited areas of expansion would have been an increasingly pressing issue after the expansion through the major continents by 14,600 years ago.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">A changing global climate immediately preceded the transition to agriculture, so researchers have also explored a connection between the two events. Since the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1789\">Last Glacial Maximum<\/a><\/strong> of 23,000 years ago, the Earth slowly warmed. Then, from 13,000 to 11,700 years ago, the temperature in most of the Northern Hemisphere dropped suddenly in a phenomenon called the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1790\"><strong>Younger Dryas<\/strong>.<\/a> Glaciers returned in Europe, Asia, and North America. In Mesopotamia, which includes the Levant, the climate changed from warm and humid to cool and dry. The change would have occurred over decades, disrupting the usual nomadic patterns and subsistence of foragers around the world. The disruption to foragers due to the temperature shift could have been a factor in spurring a transition to agriculture. Researchers Gregory K. Dow and colleagues (2009) believe that foraging bands would have clustered in the new resource-rich places where people started to direct their labour to farming the limited area. After the Younger Dryas ended, people expanded out of the clusters with their agricultural knowledge (Figure 13.24).<\/p>\n<figure style=\"width: 570px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image7-6.png\" alt=\"Map shows that agriculture was invented in at least six parts of the world.\" width=\"570\" height=\"267\" \/><figcaption class=\"wp-caption-text\">Figure 13.24: The map shows the areas where agriculture was independently invented around the world and where they spread. Blue arrows show the spread of agriculture from these zones to other regions. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\">A full text description of this image is available<\/a>. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Centres_of_origin_and_spread_of_agriculture.svg\">Centres of origin and spread of agriculture<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Joe_Roe\">Joe Roe<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The double threat of the limitation of human continental expansion and the sudden global climate change may have placed bands in peril as more populations outpaced their environment\u2019s carrying capacity. Not only had a growing population may have led to increased competition with other bands, but environments worldwide had shifted to create more uncertainty. As such, it has been proposed that as people in different areas around the world faced this unpredictable situation, they became the independent inventors of agriculture.<\/p>\n<h2 class=\"import-Normal\"><strong>Agriculture around the World<\/strong><\/h2>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Due to global changes to the human experience starting from 12,000 years ago, it has been suggested that cultures with no knowledge of each other turned toward intensely farming their local resources (see Figure 13.24).\u00a0 It is proposed that the first farmers engaged in artificial selection of their domesticates to enhance useful traits over generations. The switch to agriculture took time and effort with no guarantee of success and constant challenges (e.g. fires, droughts, diseases, and pests). The regions with the most widespread impact in the face of these obstacles became the primary centres of agriculture (Figure 13.25; Fuller 2010):<\/p>\n<ul>\n<li class=\"import-Normal\" style=\"text-indent: 0pt\">Mesopotamia: The Fertile Crescent from the Tigris and Euphrates rivers through the Levant was where bands started to domesticate plants and animals around 12,000 years ago. The connection between the development of agriculture and the Younger Dryas was especially strong here. Farmed crops included wheat, barley, peas, and lentils. This was also where cattle, pigs, sheep, and goats were domesticated.<\/li>\n<li class=\"import-Normal\" style=\"text-indent: 0pt\">South and East Asia: Multiple regions across this land had varieties of rice, millet, and soybeans by 10,000 years ago. Pigs were farmed with no connection to Mesopotamia. Chickens were also originally from this region, bred for fighting first and food second.<\/li>\n<li class=\"import-Normal\" style=\"text-indent: 0pt\">New Guinea: Agriculture started here 10,000 years ago. Bananas, sugarcane, and taro were native to this island. Sweet potatoes were brought back from voyages to South America around the year C.E. 1000. No known animal farming occurred here.<\/li>\n<li class=\"import-Normal\" style=\"text-indent: 0pt\">Mesoamerica: Agriculture from Central Mexico to northern South America also occurred from 10,000 years ago; it was also only plant based. Maize was a crop bred from teosinte grass, which has become one of the global staples. Beans, squash, and avocados were also grown in this region.<\/li>\n<li class=\"import-Normal\" style=\"text-indent: 0pt\">The Andes: Starting around 8,000 years ago, local domesticated plants started with squash but later included potatoes, tomatoes, beans, and quinoa. Maize was brought down from Mesoamerica. The main farm animals were llamas, alpacas, and guinea pigs.<\/li>\n<li class=\"import-Normal\" style=\"text-indent: 0pt\">Sub-Saharan Africa: This region went through a change 5,000 years ago called the Bantu expansion. The Bantu agriculturalists were established in West Central Africa and then expanded south and east. Native varieties of rice, yams, millet, and sorghum were grown across this area. Cattle were also domesticated here.<\/li>\n<li class=\"import-Normal\" style=\"text-indent: 0pt\">Eastern North America: This region was the last major independent agriculture centre, from 4,000 years ago. Squash and sunflower are the produce from this region that are most known today, though sumpweed and pitseed goosefoot were also farmed. Hunting was still the main source of animal products.<\/li>\n<\/ul>\n<figure style=\"width: 482px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image23-1-1.jpg\" alt=\"Farmers plow a flooded field. Each plow is pulled by two oxen. \" width=\"482\" height=\"320\" \/><figcaption class=\"wp-caption-text\">Figure 13.25: Rice farmers in the present day using draft cattle to prepare their field. Credit: <a href=\"https:\/\/www.flickr.com\/photos\/ricephotos\/7554483250\">Plowing muddy field using cattle<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/ricephotos\/\">IRRI Photos<\/a> (International Rice Research Institute) has been modified (colour modified) and is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\">CC BY-NC-SA 2.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">By 5,000 years ago, our species was well within the Neolithic Revolution. Agriculturalists spread to neighbouring parts of the world with their domesticates, further expanding the use of this subsistence strategy. From this point, the human species changed from being primarily foragers to primarily agriculturalists with skilled control of their environments. The planet changed from mostly unaffected by human presence to being greatly transformed by humans. The revolution took millennia, but it was a true revolution as our species\u2019 lifestyle was dramatically reshaped.<\/p>\n<h3 class=\"import-Normal\"><strong>Cultural Effects of Agriculture<\/strong><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The worldwide adoption of agriculture altered the course of human culture and history forever. The core change in human culture due to agriculture is the move toward not moving: rather than live a nomadic lifestyle, farmers had to remain in one area to tend to their crops and livestock. The term for living bound to a certain location is <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1793\">sedentarism<\/a><\/strong>. This led to new aspects of life that were uncommon among foragers: the construction of permanent shelters and agricultural infrastructure, such as fields and irrigation, plus the development of storage technology, such as pottery, to preserve extra resources in case of future instability.<\/p>\n<figure style=\"width: 359px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image20-1-1.jpg\" alt=\"Multistory buildings surrounding a greek-style plaza.\" width=\"359\" height=\"270\" \/><figcaption class=\"wp-caption-text\">Figure 13.26: View of downtown San Diego taken by the author at a shopping complex during a break from jury duty. Here, people live amongst structures that facilitate commerce, government, tourism, and art. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-14\/\">Downtown San Diego (October 13, 2016; Figure 12.28)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Keith Chan is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\"> CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The high productivity of successful agriculture sparked further changes (Smith 2009). It is argued that since successful agriculture produced a much greater amount of food and other resources per unit of land compared to foraging, the population growth rate skyrocketed. The surplus of a bountiful harvest also provided insurance for harder times, reducing the risk of famine and bringing change to society as well. With a few farming households producing enough food to feed many others, people could start specializing in roles such as craftspeople, traders, religious figures, and artists, spurring innovation in these areas as people could now devote time and effort toward specific skills. These interdependent people would settle an area together for convenience, and over time, the growth of these settlements led to <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1794\">urbanization<\/a><\/strong>, the founding of cities that became the foci of human interaction (Figure 13.26).<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The formation of cities led to new issues that sparked the growth of further specializations, called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1795\">institutions<\/a><\/strong>. These are cultural constructs that exist beyond the individual and have wide control over a population. Leadership of these cities became hierarchical with different levels of rank and control. The stratification of society increased social inequality between those with more or less power over others. Under leadership, people built impressive <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1796\">monumental architecture<\/a><\/strong>, such as pyramids and palaces, that embodied the wealth and power of these early cities. Alliances could unite cities, forming the earliest states. In several regions of the world, state organization expanded into empires, wide-ranging political entities that covered a variety of cultures.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Urbanization brought new challenges as well. The concentration of sedentary peoples was ideal for infectious diseases to thrive since they could jump from person to person and even from livestock to person (Armelagos, Brown, and Turner 2005). While successful agriculture provided a large surplus of food to thwart famine, the food produced offered less diverse food sources than foragers\u2019 diets (Cohen and Armelagos 1984; Cohen and Crane-Kramer 2007). This shift in nutrition caused other diseases to flourish among those who adopted farming, such as dental cavities and malocclusion (the misalignment of teeth caused by soft, agricultural diets). The need to extract \u201cwisdom teeth\u201d or third molars seen in agricultural cultures today stems from this misalignment between the environment our ancestors adapted to and our lifestyles today.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">As the new disease trends show, the adoption of agriculture and the ensuing cultural changes were not entirely positive. It is also important to note that this is not an absolutely linear progression of human culture from simple to complex. In many cases, empires have collapsed and, in some cases, cities dispersed to low-density bands that rejected institutions. However, a global trend has emerged since the adoption of agriculture, wherein population and social inequality have increased, leading to the massive and influential nation-states of today.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The rise of states in Europe has a direct impact on many of this book\u2019s topics. Science started as a European cultural practice by the upper class that became a standardized way to study the world. Education became an institution to provide a standardized path toward producing and gaining knowledge. The scientific study of human diversity, embroiled in the race concept that still haunts us today, was connected to the European slave trade and colonialism.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Also starting in Europe, the Industrial Revolution of the 19th century turned cities into centres of mass manufacturing and spurred the rapid development of inventions (Figure 13.27). In the technologically interconnected world of today, human society has reached a new level of complexity with <strong>globalization<\/strong>. In this system, goods are mass-produced and consumed in different parts of the world, weakening the reliance on local farms and factories. The imbalanced relationship between consumers and producers of goods further increases economic inequality.<\/p>\n<p>&nbsp;<\/p>\n<figure style=\"width: 465px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image1-3.jpg\" alt=\"A yellow farm vehicle driving into crops in a field.\" width=\"465\" height=\"310\" \/><figcaption class=\"wp-caption-text\">Figure 13.27: This combine harvester can collect and process grain at a massive scale. Our food now commonly comes from enormous farms located around the world. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Combine_CR9060.jpeg\">Combine CR9060<\/a> by Hertzsprung is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">As states based on agriculture and industry keep exerting influence on humanity today, there are people, like the Hadzabe of Tanzania, who continue to live a lifestyle centred on foraging. Due to the overwhelming force that agricultural societies exert, foragers today have been marginalized to live in the least habitable parts of the world\u2014the areas that are not conducive to farming, such as tropical rainforests, deserts, and the Arctic (Headland Et al. 1989). Foragers can no longer live in the abundant environments that humans would have enjoyed before the Neolithic Revolution. Interactions with agriculturalists are typically imbalanced, with trade and other exchanges heavily favouring the larger group. One of anthropology\u2019s important roles today is to intelligently and humanely manage equitable interactions between people of different backgrounds and levels of influence.<\/p>\n<div class=\"textbox\">\n<h2 class=\"import-Normal\">Special Topic: Indigenous Land Management<\/h2>\n<p class=\"import-Normal\">Insight into the lives of past modern humans has evolved as researchers revise previous theories and establish new connections with Indigenous knowledge holders.<\/p>\n<p class=\"import-Normal\">The outdated view of foraging held that people lived off of the land without leaving an impact on the environment. Accompanying this idea was anthropologist Marshall Sahlins\u2019s (1968) proposal that foragers were the \u201coriginal affluent society\u201d since they were meeting basic needs and achieving satisfaction with less work hours than agriculturalists and city-dwellers. This view countered an earlier idea that foragers were always on the brink of starvation. Sahlins\u2019s theory took hold in the public eye as an attractive counterpoint to our busy contemporary lives in which we strive to meet our endless wants.<\/p>\n<p class=\"import-Normal\">A fruitful type of study involving researchers collaborating with Indigenous experts has found that foragers did not just live off the land with minimal effort nor were they barely surviving in unchanging environments. Instead, they shaped the landscape to their needs using labour and strategies that were more subtle than what European colonizers and subsequent researchers were used to seeing. Research from two regions shows the latest developments in understanding Indigenous land management.<\/p>\n<p class=\"import-Normal\">In British Columbia, Canada, the bridging of scientific and Indigenous perspectives has shown that the forests of the region are not untouched wilderness but, rather, have been crafted by Indigenous peoples thousands of years ago. Forest gardens adjacent to archaeological sites show higher plant diversity than unmanaged places even after 150 years (Armstrong Et al. 2021). On the coast, 3,500-year-old archaeological sites are evidence of constructed clam gardens, according to Indigenous experts (Lepofsky Et al. 2015). Another project, in consultation with Elders of the T\u2019exelc (William Lakes First Nation) in British Columbia, introduced researchers to explanations of how forests were managed before the practice was disrupted by European colonialism (Copes-Gerbitz Et al. 2021). Careful management of controlled fires reduced the density of the forest to favour plants such as raspberries and allow easier movement through the landscape.<\/p>\n<p class=\"import-Normal\">Similarly, the study of landscapes in Australia, in consultation with Aboriginal Australians today, shows that areas previously considered wilderness by scientists were actually the result of controlling fauna and fires. The presence of grasslands with adjacent forests were purposely constructed to attract kangaroos for hunting (Gammage 2008). People also managed other animal and insect life, from emus to caterpillars. In Tasmania, a shift from productive grassland to wildfire-prone rainforest occurred after Aboriginal Australian land management was replaced by British colonial rule (Fletcher, Hall, and Alexander 2021). The site of Budj Bim of the Gunditjmara people has archaeological features of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1798\">aquaculture<\/a><\/strong>, or the farming of fish, that date back 6,600 years (McNiven Et al. 2012; McNiven Et al. 2015). These examples show that Indigenous knowledge of how to manipulate the environment may be invaluable at the state level, such as by creating an Aboriginal ranger program to guide modern land management.<\/p>\n<\/div>\n<h2 class=\"import-Normal\">The Future of Humanity<\/h2>\n<p class=\"import-Normal\">A common question stemming from understanding human evolution is: What will the genetic and biological traits of our species be hundreds of thousands of years in the future? When faced with this question, people tend to think of directional selection. Maybe our braincases will be even larger, resembling the large-headed and small-bodied aliens of science fiction (Figure 13.28). Or, our hands could be specialized for interacting with our touch-based technology with less risk of repetitive injury. These ideas do not stand up to scrutiny. Since natural selection is based on adaptations that increase reproductive success, any directional change must be due to a higher rate of producing successful offspring compared to other alleles. Larger brains and more agile fingers would be convenient to possess, but they do not translate into an increase in the underlying allele frequencies.<\/p>\n<figure style=\"width: 571px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image8-4.png\" alt=\"One human has typical features; the other has a tall braincase.\" width=\"571\" height=\"279\" \/><figcaption class=\"wp-caption-text\">Figure 13.28: Will we evolve toward even more globular brains? Actually, this trend is not likely to continue for our species. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-14\/\">Hypothetical image of future human evolution (Figure 12.30)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Scientists are hesitant to professionally speculate on the unknowable, and we will never know what is in store for our species one thousand or one million years from now, but there are two trends in human evolution that may carry on into the future: increased genetic variation and a reduction in regional differences.<\/p>\n<p class=\"import-Normal\">Rather than a directional change, genetic variation in our species could expand. Our technology can protect us from extreme environments and pathogens, even if our biological traits are not tuned to handle these stressors. The rapid pace of technological advancement means that biological adaptations will become less and less relevant to reproductive success, so nonbeneficial genetic traits will be more likely to remain in the gene pool. Biological anthropologist Jay T. Stock (2008) views environmental stress as needing to defeat two layers of protection before affecting our genetics. The first layer is our cultural adaptations. Our technology and knowledge can reduce pressure on one\u2019s genotype to be \u201cjust right\u201d to pass to the next generation. The second defence is our flexible physiology, such as our acclimatory responses. Only stressors not handled by these powerful responses would then cause natural selection on our alleles. These shields are already substantial, and cultural adaptations will only keep increasing in strength.<\/p>\n<p class=\"import-Normal\">The increasing ability to travel far from one\u2019s home region means that there will be a mixing of genetic variation on a global level in the future of our species. In recent centuries, gene flow of people around the world has increased, creating admixture in populations that had been separated for tens of thousands of years. For skin colour, this means that populations all around the world could exhibit the whole range of skin colours, rather than the current pattern of decreasing melanin pigment farther from the equator. The same trend of intermixing would apply to all other traits, such as blood types. While our genetics will become more varied, the variation will be more intermixed instead of regionally isolated.<\/p>\n<p class=\"import-Normal\">Our distant descendants will not likely be dextrous ultraintellectuals; more likely, they will be a highly variable and mobile species supported by novel cultural adaptations that make up for any inherited biological limitations. Technology may even enable the editing of DNA directly, changing these trends. With the uncertainty of our future, these are just the best-educated guesses for now. Our future is open and will be shaped little by little by the environment, our actions, and the actions of our descendants.<\/p>\n<h2>Cultural Connections and Contemporary Implications<\/h2>\n<p>The expansion of <em>Homo sapiens<\/em> across the globe and the subsequent and increasingly complex societies they developed have fundamentally altered the relationship between humans and the natural world. Throughout this chapter, we have seen how cultural innovations\u2014agriculture, urbanization, and technological development\u2014enabled humans to modify the environment in ways that no previous hominin could. At this point, the cumulative changes by <em>Homo sapiens<\/em> have irreversibly changed the planet, and some anthropologists and Earth scientists argue that we have entered a new stage of Earth\u2019s history known as the <em>Anthropocene<\/em> (notably the Nobel Laureate Paul J. Crutzen, known as one of the forces in popularizing the term and his part in the <em>Montreal Protocol; <\/em>cf<em>. <\/em>United Nations, 1987; Steffen, 2021<\/p>\n<p>The Anthropocene (or <em>Human Epoch<\/em>) describes a period in which natural processes and human activities have become inseparable, such that the future of Earth's ecosystems and humanity are increasingly dependent on one another (Steffen, 2021). This proposed epoch emphasizes humans\u2019 role as a planetary force capable of reshaping Earth on multiple levels; landscapes are transformed by mining, dam construction, urban expansion, and resource extraction. With this, we are witnessing increasing extinction, the introduction of invasive species, and genetic modification of organisms and unlike earlier periods of human evolution, these changes are occurring simultaneously across the entire planet, affecting ecological systems on a global scale. Although the Anthropocene has been proposed as a new geological epoch beginning in the mid-twentieth century, it has been refused formal adoption within the Geological Time Scale It is generally considered as a part of the Holocene, where agriculture and pastoralism significantly changed the earth despite an argument from a working group in the IPCC (Waters, C 2016).<\/p>\n<p>Nevertheless, the concept of the Anthropocene places modern human societies in positions of unprecedented responsibility. Climate change is not experienced equally, with poverty and social inequality increasing the vulnerability to these challenges, framing the Anthropocene as an environmental concept and a biocultural one as well. Just as agriculture transformed human societies, the choices made by modern populations regarding energy use, technology, and resource management will shape the environments inhabited by future generations and the continued evolution of our species. The Anthropocene therefore reminds us that anthropology and other disciplines aide us in understanding the evolutionary past they are also essential for understanding humanity's role in shaping the future.<\/p>\n<h4>Discussion questions<\/h4>\n<ul>\n<li>How do you see humans shaping the Earth today? Which of these changes do you consider permanent, temporary, harmful, or beneficial?<\/li>\n<li>How might the Anthropocene affect humans as a species? Like other species affected by environmental change, do you think humans could face extinction, or will our ability to modify our environment allow us to adapt?<\/li>\n<li>If humans eventually become a multiplanetary species, would the Anthropocene simply continue beyond Earth? What might this mean for our relationship with the environments we inhabit?<\/li>\n<\/ul>\n<div class=\"textbox\">\n<h2 class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">Hominin Species Summary<\/span><\/h2>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 450pt\">\n<tbody>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Hominin<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">Modern<em> Homo sapiens<\/em><\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Dates<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">315,000 years ago to present<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Region(s)<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Starting in Africa, then expanding around the world<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Famous discoveries<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 1.5pt;text-indent: 0pt\"><span style=\"color: #000000\">Cro-Magnon individuals, discovered 1868 in Dordogne, France. Otzi the Ice Man, discovered 1991 in the Alps between Austria and Italy. Kennewick man, discovered 1996 in Washington state.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Brain size<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">1400 cc average<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Dentition<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">Extremely small with short cusps.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Cranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">An extremely globular brain case and gracile features throughout the cranium. The mandibular symphysis forms a chin at the anterior-most point.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Postcranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Gracile skeleton adapted for efficient bipedal locomotion at the expense of the muscular strength of most other large primates.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Culture<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Extremely extensive and varied culture with many spoken and written languages. Art is ubiquitous. Technology is broad in complexity and impact on the environment.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Other<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">The only living hominin. Chimpanzees and bonobos are the closest living relatives.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div class=\"textbox shaded\">\n<h2 class=\"import-Normal\">Summary<\/h2>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Modern <em>Homo sapiens<\/em> is the species that took the hominin lifestyle the furthest to become the only living member of that lineage. The largest factor that allowed us to persist while other hominins went extinct was likely our advanced ability to culturally adapt to a wide variety of environments. Our species, with its skeletal and behavioural traits, was well-suited to be generalist-specialists who successfully foraged across most of the world\u2019s environments. The biological basis of this adaptation was our reorganized brain that facilitated innovation in cultural adaptations and intelligence for leveraging our social ties and finding ways to acquire resources from the environment. As the brain\u2019s ability increased, it shaped the skull by reducing the evolutionary pressure to have large teeth and robust cranial bones to produce the modern <em>Homo sapiens<\/em> face.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Our ability to be generalist-specialists is seen in the geographical range that modern <em>Homo sapiens<\/em> covered in 300,000 years. In Africa, our species formed from multiregional gene flow that loosely connected archaic humans across the continent. People then expanded out to the rest of the continental Eurasia and even further to the Americas.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">For most of our species\u2019s existence, foraging was the general subsistence strategy within which people specialized to culturally adapt to their local environment. With omnivorousness and mobility, people found ways to extract and process resources, shaping the environment in return. When resource uncertainty hit the species, people around the world focused on agriculture to have a firmer control of sustenance. The new strategy shifted human history toward exponential growth and innovation, leading to our high dependence on cultural adaptations today.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">While a cohesive image of our species has formed in recent years, there is still much to learn about our past. The work of many driven researchers shows that there are amazing new discoveries made all the time that refine our knowledge of human evolution. Technological innovations such as DNA analysis enable scientists to approach lingering questions from new angles. The answers we get allow us to ask even more insightful questions that will lead us to the next revelation. Like the pink limestone strata at Jebel Irhoud, previous effort has taken us so far and you are now ready to see what the next layer of discovery holds.<\/p>\n<h2 class=\"import-Normal\">Review Questions<strong><br \/>\n<\/strong><\/h2>\n<ul>\n<li>What are the skeletal and behavioural traits that define modern <em>Homo sapiens<\/em>? What are the evolutionary explanations for its presence?<\/li>\n<li>What are some creative ways that researchers have learned about the past by studying fossils and artifacts?<\/li>\n<li>How do the discoveries mentioned in \u201cFirst Africa, Then the World\u201d fit the Assimilation model?<\/li>\n<li>What is foraging? What adaptations do we have for this subsistence strategy? Could you train to be a skilled forager?<\/li>\n<li>What are aspects of your life that come from dependence on agriculture and its cultural effects? Where did the ingredients of your favourite foods originate from?<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<h2 class=\"__UNKNOWN__\">Key Terms<\/h2>\n<div class=\"__UNKNOWN__\">\n<p class=\"import-Normal\"><strong>African multiregionalism<\/strong>: The idea that modern <em>Homo sapiens<\/em> evolved as a complex web of small regional populations with sporadic gene flow among them.<\/p>\n<p class=\"import-Normal\"><strong>Agriculture<\/strong>: The mass production of resources through farming and domestication.<\/p>\n<p class=\"import-Normal\"><strong>Aquaculture<\/strong>: The farming of fish using techniques such as trapping, channels, and artificial ponds.<\/p>\n<p class=\"import-Normal\"><strong>Assimilation <\/strong><strong>hypothesis<\/strong>: Current theory of modern human origins stating that the species evolved first in Africa and interbred with archaic humans of Europe and Asia.<\/p>\n<p class=\"import-Normal\"><strong>Atlatl<\/strong>: A handheld spear thrower that increased the force of thrown projectiles.<\/p>\n<p class=\"import-Normal\"><strong>Band<\/strong>: A small group of people living together as foragers.<\/p>\n<p class=\"import-Normal\"><strong>Beringia<\/strong>: Ancient landmass that connected Siberia and Alaska. The ancestors of Indigenous Americans would have crossed this area to reach the Americas.<\/p>\n<p class=\"import-Normal\"><strong>Carrying capacity<\/strong>: The amount of organisms that an environment can reliably support.<\/p>\n<p class=\"import-Normal\"><strong>Coastal Route model<\/strong>: Theory that the first Paleoindians crossed to the Americas by following the southern coast of Beringia.<\/p>\n<p class=\"import-Normal\"><strong>Early Modern <\/strong><strong><em>Homo sapiens<\/em><\/strong><strong>, Early Anatomically Modern Human<\/strong>: Terms used to refer to transitional fossils between archaic and modern <em>Homo sapiens<\/em> that have a mosaic of traits. Humans like ourselves, who mostly lack archaic traits, are referred to as Late Modern <em>Homo sapiens<\/em> and simply Anatomically Modern Humans.<\/p>\n<p class=\"import-Normal\"><strong>Egalitarian<\/strong>: Human organization without strict ranks. Foraging societies tend to be more egalitarian than those based on other subsistence strategies.<\/p>\n<p class=\"import-Normal\"><strong>Foraging<\/strong>: Lifestyle consisting of frequent movement through the landscape and acquiring resources with minimal storage capacity.<\/p>\n<p class=\"import-Normal\"><strong>Generalist-specialist niche<\/strong>: The ability to survive in a variety of environments by developing local expertise. Evolution toward this niche may have been what allowed modern <em>Homo sapiens<\/em> to expand past the geographical range of other human species.<\/p>\n<p class=\"import-Normal\"><strong>Globalization<\/strong>: A recent increase in the interconnectedness and interdependence of people that is facilitated with long-distance networks.<\/p>\n<p class=\"import-Normal\"><strong>Globular<\/strong>: Having a rounded appearance. Increased globularity of the braincase is a trait of modern <em>Homo sapiens<\/em>.<\/p>\n<p class=\"import-Normal\"><strong>Gracile<\/strong>: Having a smooth and slender quality; the opposite of robust.<\/p>\n<p class=\"import-Normal\"><strong>Holocene<\/strong>: The epoch of the Cenozoic Era starting around 12,000 years ago and lasting arguably through the present.<\/p>\n<p class=\"import-Normal\"><strong>Ice-Free Corridor model<\/strong>: Theory that the first Native Americans crossed to the Americas through a passage between glaciers.<\/p>\n<p class=\"import-Normal\"><strong>Institutions<\/strong>: Long-lasting and influential cultural constructs. Examples include government, organized religion, academia, and the economy.<\/p>\n<p class=\"import-Normal\"><strong>Last Glacial Maximum<\/strong>: The time 23,000 years ago when the most recent ice age was the most intense.<\/p>\n<p class=\"import-Normal\"><strong>Later Stone Age<\/strong>: Time period following the Middle Stone Age with a diversification in tool types, starting around 50,000 years ago.<\/p>\n<p class=\"import-Normal\"><strong>Levant<\/strong>: The eastern coast of the Mediterranean. The site of early modern human expansion from Africa and later one of the centres of agriculture.<\/p>\n<p class=\"import-Normal\"><strong>Megafauna<\/strong>: Large ancient animals that may have been hunted to extinction by people around the world.<\/p>\n<p class=\"import-Normal\"><strong>Mental eminence<\/strong>: The chin on the mandible of modern <em>H. sapiens<\/em>. One of the defining traits of our species.<\/p>\n<p class=\"import-Normal\"><strong>Microlith<\/strong>: Small stone tool found in the Later Stone Age; also called a bladelet.<\/p>\n<p class=\"import-Normal\"><strong>Middle Stone Age<\/strong>: Time period known for Mousterian lithics that connects African archaic to modern <em>Homo sapiens<\/em>.<\/p>\n<p class=\"import-Normal\"><strong>Monumental architecture<\/strong>: Large and labour-intensive constructions that signify the power of the elite in a sedentary society. A common type is the pyramid, a raised crafted structure topped with a point or platform.<\/p>\n<p class=\"import-Normal\"><strong>Mosaic<\/strong>: Composed from a mix or composite of traits.<\/p>\n<p class=\"import-Normal\"><strong>Neolithic Revolution<\/strong>: Time of rapid change to human cultures due to the invention of agriculture, starting around 12,000 years ago.<\/p>\n<p class=\"import-Normal\"><strong>Ochre<\/strong>: Iron-based mineral pigment that can be a variety of yellows, reds, and browns. Used by modern human cultures worldwide since at least 80,000 years ago.<\/p>\n<p class=\"import-Normal\"><strong>Sahul<\/strong>: Ancient landmass connecting New Guinea and Australia.<\/p>\n<p class=\"import-Normal\"><strong>Sedentarism<\/strong>: Lifestyle based on having a stable home area; the opposite of nomadism.<\/p>\n<p class=\"import-Normal\"><strong>Southern Dispersal model<\/strong>: Theory that modern <em>H. sapiens<\/em> expanded from East Africa by crossing the Red Sea and following the coast east across Asia.<\/p>\n<p class=\"import-Normal\"><strong>Subsistence strategy<\/strong>: The method an organism uses to find nourishment and other resources.<\/p>\n<p class=\"import-Normal\"><strong>Sunda<\/strong>: Ancient Asian landmass that incorporated modern Southeast Asia.<\/p>\n<p class=\"import-Normal\"><strong>Supraorbital torus<\/strong>: The bony brow ridge across the top of the eye orbits on many hominin crania.<\/p>\n<p class=\"import-Normal\"><strong>Upper Paleolithic<\/strong>: Time period considered synonymous with the Later Stone Age.<\/p>\n<p class=\"import-Normal\"><strong>Urbanization<\/strong>: The increase of population density as people settled together in cities.<\/p>\n<p class=\"import-Normal\"><strong>Wallacea<\/strong>: Archipelago southeast of Sunda with different biodiversity than Asia.<\/p>\n<p class=\"import-Normal\"><strong>Younger Dryas<\/strong>: The rapid change in global climate\u2014notably a cooling of the Northern Hemisphere\u201413,000 years ago.<\/p>\n<h2 class=\"import-Normal\">For Further Exploration<\/h2>\n<h3 class=\"import-Normal\" style=\"text-indent: 0pt\"><strong>Websites<\/strong><\/h3>\n<p>First-person virtual tour of Lascaux cave with annotated cave art: Minist\u00e8re de la Culture and Mus\u00e9e d\u2019Arch\u00e9ologie Nationale. \u201c<a href=\"https:\/\/archeologie.culture.fr\/lascaux\/en\/visit-cave\" target=\"_blank\" rel=\"noopener\">Visit the cave<\/a>\u201d Lascaux website.<\/p>\n<p>Online anthropology magazine articles related to paleoanthropology and human evolution: SAPIENS. \u201c<a href=\"https:\/\/www.sapies.org\/category\/evolution\/\" target=\"_blank\" rel=\"noopener\">Evolution<\/a>.\u201d <em>SAPIENS<\/em> website.<\/p>\n<p>Various presentations of information about hominin evolution: Smithsonian Institution. \u201c<a href=\"https:\/\/humanorigins.si.edu\" target=\"_blank\" rel=\"noopener\">What does it mean to be human?<\/a>\u201d <em>Smithsonian National Museum of Natural History<\/em> website.<\/p>\n<p>Magazine-style articles on archaeology and paleoanthropology: ThoughtCo. \u201c<a href=\"https:\/\/www.thoughtco.com\/archaeology-4133504\" target=\"_blank\" rel=\"noopener\">Archaeology<\/a>.\u201d ThoughtCo. Website.<\/p>\n<p>Database of comparisons across hominins and primates: University of California, San Diego. \u201c<a href=\"https:\/\/carta.anthropogeny.org\/moca\/domains\" target=\"_blank\" rel=\"noopener\">MOCA Domains<\/a>.\u201d <em>Center for Academic Research &amp; Training in Anthropogeny<\/em> website.<\/p>\n<h3><strong>Books<\/strong><\/h3>\n<p>Engaging book that covers human-made changes to the environment with industrialization and globalization: Kolbert, Elizabeth. 2014. <em>The Sixth Extinction: An Unnatural History<\/em>. New York: Bloomsbury.<\/p>\n<p>Overview of what human life was like among the environmental shifts of the Ice Age: Woodward, Jamie. 2014. <em>The Ice Age: A Very Short Introduction<\/em>. Oxford: OUP Press.<\/p>\n<h3><strong>Articles<\/strong><\/h3>\n<p>Recent review paper about the current state of paleoanthropology research: Stringer, C. 2016. \u201c<a href=\"https:\/\/doi.org\/10.1098\/rstb.2015.0237\" target=\"_blank\" rel=\"noopener\">The Origin and Evolution of <em>Homo sapiens<\/em><\/a>.\u201d <em>Philosophical Transactions of the Royal Society B<\/em> 371 (1698).<\/p>\n<p>Overview of the history of American paleoanthropology and the many debates that have occurred over the years: Trinkaus, E. 2018. \u201cOne Hundred Years of Paleoanthropology: An American Perspective.\u201d <em>American Journal of Physical Anthropology<\/em> 165 (4): 638\u2013651.<\/p>\n<p>Amazing magazine article that synthesizes hominin evolution and why it is important to study this subject: Wheelwright, Jeff. 2015. \u201c<a href=\"https:\/\/discovermagazine.com\/2015\/may\/16-days-of-dysevolution\" target=\"_blank\" rel=\"noopener\">Days of Dysevolution<\/a>.\u201d <em>Discover<\/em> 36 (4): 33\u201339.<\/p>\n<p>Fascinating research on \u00d6tzi, a mummy from 5,000 years ago: Wierer, Ursula, Simona Arrighi, Stefano Bertola, G\u00fcnther Kaufmann, Benno Baumgarten, Annaluisa Pedrotti, Patrizia Pernter, and Jacques Pelegrin. 2018. \u201cThe Iceman\u2019s Lithic Toolkit: Raw Material, Technology, Typology and Use.\u201d <em>PLOS One<\/em> 13 (6): e0198292. https:\/\/doi.org\/10.1371\/journal.pone.0198292.<\/p>\n<h3><strong>Documentaries<\/strong><\/h3>\n<p>PBS NOVA series covering the expansion of modern <em>Homo sapiens<\/em> and interbreeding with archaic humans: Brown, Nicholas, dir. 2015. <em>First Peoples<\/em>. Edmonton: Wall to Wall Television. Amazon Prime Video.<\/p>\n<p>PBS NOVA special featuring the footprints found in White Sands National Park: Falk, Bella, dir. 2016. <em>Ice Age Footprints<\/em>. Boston: Windfall Films. https:\/\/www.pbs.org\/wgbh\/nova\/video\/ice-age-footprints\/.<\/p>\n<p>PBS NOVA special about how modern humans evolved adaptations to different environments. Shows how present-day people live around the world: Thompson, Niobe, dir. 2016. <em>Great Human Odyssey<\/em>. Edmonton: Clearwater Documentary. <a class=\"rId132\" href=\"https:\/\/www.pbs.org\/wgbh\/nova\/evolution\/great-human-odyssey.html\">https:\/\/www.pbs.org\/wgbh\/nova\/evolution\/great-human-odyssey.html<\/a>.<\/p>\n<\/div>\n<h2 class=\"__UNKNOWN__\">References<\/h2>\n<div class=\"__UNKNOWN__\">\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Araujo, Bernardo B. A., Luiz Gustavo R. Oliveira-Santos, Matheus S. Lima-Ribeiro, Jos\u00e9 Alexandre F. Diniz-Filho, and Fernando A. S. 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Beaumont. 2012. \u201cEarly Evidence of San Material Culture Represented by Organic Artifacts from Border Cave, South Africa.\u201d <em>Proceedings of the National Academy of Sciences<\/em> 109 (33): 13214\u201313219.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">d\u2019Errico, Francesco, Christopher Henshilwood, Marian Vanhaeren, and Karen Van Niekerk. 2005. \u201cNassarius Kraussianus Shell Beads from Blombos Cave: Evidence for Symbolic Behaviour in the Middle Stone Age.\u201d <em>Journal of Human Evolution<\/em> 48 (1): 3\u201324.<\/p>\n<p class=\"import-Normal\">Dannemann, Michael, and Fernando Racimo. 2018. \u201cSomething Old, Something Borrowed: Admixture and Adaptation in Human Evolution.\u201d <em>Current Opinion in Genetics &amp; Development<\/em> 53: 1\u20138.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Day, M. 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Clark Howell. 2003. \u201cPleistocene <em>Homo sapiens<\/em> from Middle Awash, Ethiopia.\u201d <em>Nature<\/em> 423 (6941): 742\u2013747.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Woo, Ju-Kang. 1959. \u201cHuman Fossils Found in Liukiang, Kwangsi, China.\u201d <em>Vertebrata PalAsiatica<\/em> 3 (3): 109\u2013118.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Wu, XiuJie, Wu Liu, Wei Dong, JieMin Que, and YanFang Wang. 2008. \u201cThe Brain Morphology of Homo Liujiang Cranium Fossil by Three-Dimensional Computed Tomography.\u201d <em>Chinese Science Bulletin<\/em> 53 (16): 2513\u20132519.<\/p>\n<h2 class=\"import-Normal\">Acknowledgements<\/h2>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">I could not have undertaken this project without the help of many who got me to where I am today. I extend sincere thank yous to the many colleagues and former students who have inspired me to keep learning and talking about anthropology. Thank you also to all who are involved in this textbook project. The anonymous reviewers truly sparked improvements to the chapter. Lastly, the staff of Starbucks #5772 also contributed immensely to this text.<\/p>\n<\/div>\n<\/div>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1695_1881\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1695_1881\"><div tabindex=\"-1\"><div class=\"__UNKNOWN__\">\n<div class=\"textbox\">\n<h6>Student contributors to this chapter: Lily Berruyer, Lyn Loytchenko, and Sarah Cupidio<\/h6>\n<p>Learn more about <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/about-the-authors\/\">authors and editors<\/a>,<a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/student-contributors\/\"> Hess' student contributions<\/a>, and <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/versioning-history\/\">versioning history<\/a>.<\/p>\n<\/div>\n<div class=\"textbox textbox--learning-objectives\">\n<header class=\"textbox__header\">\n<h2 class=\"textbox__title\">Learning Objectives<\/h2>\n<\/header>\n<div class=\"textbox__content\">\n<ul>\n<li>Identify the skeletal and behavioural traits that represent modern <em>Homo sapiens.<\/em><\/li>\n<li>Critically evaluate different types of evidence for the origin of our species in Africa and our expansion around the world.<\/li>\n<li>Understand how the human lifestyle changed when people transitioned from foraging to agriculture.<\/li>\n<li>Hypothesize how human evolutionary trends may continue into the future.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<p class=\"import-Normal\">The walls of a pink limestone cave in the hillside of Jebel Irhoud jutted out of the otherwise barren landscape of the Moroccan desert (Figure 13.1). Miners had excavated the cave in the 1960s, revealing some fossils. In 2007, a re-excavation of the site became a momentous occasion for science. A fossil cranium unearthed by a team of researchers was barely visible to the untrained eye. Just the fossil\u2019s robust brows were peering out of the rock. This research team from the Max Planck Institute for Evolutionary Anthropology was the latest to explore the ancient human presence in this part of North Africa after a find by miners in 1960. Excavating near the first discovery, the researchers wanted to learn more about how <em>Homo sapiens<\/em> lived far from East Africa, where we thought our species originated.<\/p>\n<figure style=\"width: 2500px\" class=\"wp-caption alignnone\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2023\/06\/image10-1.jpg\" alt=\"Rocky hillside with exposed layers. People are visible at the base.\" width=\"2500\" height=\"987\" \/><figcaption class=\"wp-caption-text\">Figure 13.1: The excavation of an exposed cave at Jebel Irhoud, Morocco, where hominin fossils were found in the 1960s and in 2007. Dating showed that they could represent the earliest-known modern Homo sapiens. Credit: <a href=\"https:\/\/www.eva.mpg.de\/homo-sapiens\/presskit.html\" target=\"_blank\">View looking south of the Jebel Irhoud (Morocco) site<\/a> by Shannon McPherron, <a href=\"https:\/\/www.eva.mpg.de\/index.html\" target=\"_blank\">MPI EVA Leipzig<\/a>, is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/\" target=\"_blank\">CC BY-SA 2.0 License<\/a>.<\/figcaption><\/figure>\n<p>The scientists were surprised when they analysed the cranium, named Irhoud 10, and other fossils. Statistical comparisons with other human crania concluded that the Irhoud face shapes were typical of recent modern humans while the braincases matched ancient modern humans. Based on the findings of other scientists, the team expected these modern <em>Homo sapiens<\/em> fossils to be around 200,000 years old. Instead, dating revealed that the cranium had been buried for around 315,000 years.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Together, the modern-looking facial dimensions and the older date reshaped the interpretation of our species: modern <em>Homo sapiens<\/em>. Some key evolutionary changes from the archaic <em>Homo sapiens<\/em> (described in Chapter 12) to our species today happened 100,000 years earlier than we had thought and across the vast African continent rather than concentrated in its eastern region.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">This revelation in the study of modern <em>Homo sapiens<\/em> is just one of the latest in this continually advancing area of biological anthropology. Researchers today are still discovering amazing fossils and ingenious ways to collect data and test hypotheses about our past. Through the collective work of many scientists, we are building an overall theory of modern human origins.<\/p>\n<h2 class=\"import-Normal\">Defining Modernity<\/h2>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">What defines modern <em>Homo sapiens<\/em> when compared to archaic <em>Homo sapiens<\/em>? Modern humans, like you and me, have a set of derived traits that are not seen in archaic humans or any other hominin. As with other transitions in hominin evolution, such as increasing brain size and bipedal ability, modern traits do not appear fully formed or all at once. In other words, the first modern <em>Homo sapiens<\/em> was not just born one day from archaic parents. The traits common to modern <em>Homo sapiens<\/em> appeared in a <strong>mosaic<\/strong> manner: gradually and out of sync with one another. There are two areas to consider when tracking the complex evolution of modern human traits. One is the physical change in the skeleton. The other is behaviour inferred from the size and shape of the cranium and material culture evidence.<\/p>\n<h3 class=\"import-Normal\"><strong>Skeletal Traits<\/strong><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The skeleton of modern <em>Homo sapiens<\/em> is less robust than that of archaic <em>Homo sapiens<\/em>. In other words, the modern skeleton is <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1406\">gracile<\/a><\/strong>, meaning that the structures are thinner and smoother. Differences related to gracility in the cranium are seen in the braincase, the face, and the mandible. There are also broad differences in the rest of the skeleton.<\/p>\n<h4 class=\"import-Normal\"><em>Cranial Traits<\/em><\/h4>\n<figure style=\"width: 445px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image29-2.png\" alt=\"A rounded skull facing a robust skull with sloping forehead.\" width=\"445\" height=\"221\" \/><figcaption class=\"wp-caption-text\">Figure 13.2: Comparison between modern (left) and archaic (right) Homo sapiens skulls. Note the overall gracility of the modern skull, as well as the globular braincase. Credit: <a class=\"rId15\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-14\/\" target=\"_blank\">Modern human and Neanderthal<\/a> original to <a class=\"rId16\" href=\"https:\/\/explorations.americananthro.org\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a class=\"rId17\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Several elements of the braincase differ between modern and archaic <em>Homo sapiens<\/em>. Overall, the shape is much rounder, or more <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1758\"><strong>globular<\/strong>,<\/a> on a modern skull (Lieberman, McBratney, and Krovitz 2002; Neubauer, Hublin, and Gunz 2018; Pearson 2008; Figure 13.2). You can feel the globularity of your own modern human skull. Feel the height of your forehead with the palm of your hand. Viewed from the side, the tall vertical forehead of a modern <em>Homo sapiens<\/em> stands out when compared to the sloping archaic version. This is because the frontal lobe of the modern human brain is larger than the one in archaic humans, and the skull has to accommodate the expansion. The vertical forehead reduces a trait that is common to all other hominins: the brow ridge or <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1759\">supraorbital torus<\/a><\/strong>. The parietal lobes of the brain and the matching parietal bones on either side of the skull both bulge outward more in modern humans. At the back of the skull, the archaic occipital bun is no longer present. Instead, the occipital region of the modern human cranium has a derived tall and smooth curve, again reflecting the globular brain inside.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The trend of shrinking face size across hominins reaches its extreme with our species as well. The facial bones of a modern <em>Homo sapiens<\/em> are extremely gracile compared to all other hominins (Lieberman, McBratney, and Krovitz 2002). Continuing a trend in hominin evolution, technological innovations kept reducing the importance of teeth in reproductive success (Lucas 2007). As natural selection favoured smaller and smaller teeth, the surrounding bone holding these teeth also shrank.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Related to smaller teeth, the mandible is also gracile in modern humans when compared to archaic humans and other hominins. Interestingly, our mandibles have pulled back so far from the prognathism of earlier hominins that we gained an extra structure at the most anterior point, called the <strong>mental eminence<\/strong>. You know this structure as the chin. At the skeletal level, it resembles an upside-down \u201cT\u201d at the centreline of the mandible (Pearson 2008). Looking back at archaic humans, you will see that they all lack a chin. Instead, their mandibles curve straight back without a forward point. What is the chin for and how did it develop? Flora Gr\u00f6ning and colleagues (2011) found evidence of the chin\u2019s importance by simulating physical forces on computer models of different mandible shapes. Their results showed that the chin acts as structural support to withstand strain on the otherwise gracile mandible.<\/p>\n<h4 class=\"import-Normal\"><em>Postcranial Gracility<\/em><\/h4>\n<figure style=\"width: 368px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image16-5.png\" alt=\"Two complete skeletons. The left is taller with a thinner frame.\" width=\"368\" height=\"575\" \/><figcaption class=\"wp-caption-text\">Figure 13.3: Anterior views of modern (left) and archaic (right) Homo sapiens skeletons. The modern human has an overall gracile appearance at this scale as well. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-14\/\" target=\"_blank\">Modern and archaic Homo sapiens skeletons (Figure 12.3)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p>The rest of the modern human skeleton is also more gracile than its archaic counterpart. The differences are clear when comparing a modern <em>Homo sapiens<\/em> with a cold-adapted Neanderthal (Sawyer and Maley 2005), but the trends are still present when comparing modern and archaic humans within Africa (Pearson 2000). Overall, a modern <em>Homo sapiens<\/em> postcranial skeleton has thinner cortical bone, smoother features, and more slender shapes when compared to archaic <em>Homo sapiens<\/em> (Figure 13.3). Comparing whole skeletons, modern humans have longer limb proportions relative to the length and width of the torso, giving us lankier outlines.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Why is our skeleton so gracile compared to those of other hominins? Natural selection can drive the gracilization of skeletons in several ways (Lieberman 2015). A slender frame is believed to be adapted for the efficient long-distance running ability that started with <em>Homo erectus<\/em>. Furthermore, it is argued that slenderness is a genetic adaptation for cooling an active body in hotter climates, which aligns with the ample evidence that Africa was the home continent of our species.<\/p>\n<h3 class=\"import-Normal\"><strong>Behavioural Modernity<\/strong><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Aside from physical differences in the skeleton, researchers have also uncovered evidence of behavioural changes associated with increased cultural complexity from archaic to modern humans. How did cultural complexity develop? Two investigations into this question are archaeology and the analysis of reconstructed brains.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Archaeology tells us much about the behavioural complexity of past humans by interpreting the significance of material culture. In terms of advanced culture, items created with an artistic flair, or as decoration, speak of abstract thought processes (Figure 13.4). The demonstration of difficult artistic techniques and technological complexity hints at social learning and cooperation as well. According to paleoanthropologist John Shea (2011), one way to track the complexity of past behaviour through artifacts is by measuring the variety of tools found together. The more types of tools constructed with different techniques and for different purposes, the more modern the behaviour. Researchers are still working on an archaeological way to measure cultural complexity that is useful across time and place.<\/p>\n<figure style=\"width: 221px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image15-1-1.jpg\" alt=\"A brown standing statue of a human figure with cat\u2019s head.\" width=\"221\" height=\"392\" \/><figcaption class=\"wp-caption-text\">Figure 13.4: Carved ivory figure called \u201cthe Lion-Man of the Hohlenstein-Stadel.\u201d It dates to the Aurignacian culture, between 35 and 40 kya. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Loewenmensch1.jpg\" target=\"_blank\">Loewenmensch1<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Dagmar_Hollmann\" target=\"_blank\">Dagmar Hollmann<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The interpretation of brain anatomy is another promising approach to studying the evolution of human behaviour. When looking at investigations on this topic in modern <em>Homo sapiens<\/em> brains, researchers found a weak association between brain size and test-measured intelligence (Pietschnig Et al. 2015). Additionally, they found no association between intelligence and biological sex. These findings mean that there are more significant factors that affect tested intelligence than just brain size. Since the sheer size of the brain is not useful for weighing intelligence within a species, paleoanthropologists are instead investigating the differences in certain brain structures. The differences in organization between modern <em>Homo sapiens<\/em> brains and archaic <em>Homo sapiens<\/em> brains may reflect different cognitive priorities that account for modern human culture. As with the archaeological approach, new discoveries will refine what we know about the human brain and apply that knowledge to studying the distant past.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Taken together, the cognitive abilities in modern humans may have translated into an adept use of tools to enhance survival. Researchers Patrick Roberts and Brian A. Stewart (2018) call this concept the <strong>generalist-specialist niche<\/strong>: our species is an expert at living in a wide array of environments, with populations culturally specializing in their own particular surroundings. The next section tracks how far around the world these skeletal and behavioural traits have taken us.<\/p>\n<h2 class=\"import-Normal\">First Africa, Then the World<\/h2>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">What enabled modern <em>Homo sapiens<\/em> to expand its range further in 300,000 years than <em>Homo erectus<\/em> did in 1.5 million years? The key is the set of derived biological traits from the last section. It is theorized that the gracile frame and neurological anatomy allowed modern humans to survive and even flourish in the vastly different environments they encountered. Based on multiple types of evidence, the source of all of these modern humans was Africa. Instead of originating from just one location, evidence shows that modern Homo sapiens evolution occurred in a complex gene flow network across Africa, a concept called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1760\">African multiregionalism<\/a><\/strong> (Scerri Et al. 2018).<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">This section traces the origin of modern <em>Homo sapiens<\/em> and the massive expansion of our species across all of the continents (except Antarctica) by 12,000 years ago. While modern <em>Homo sapiens<\/em> first shared geography with archaic humans, modern humans eventually spread into lands where no human had gone before. Figure 13.5 shows the broad routes that our species took expanding around the world. I encourage you to make your own timeline with the dates in this part to see the overall trends.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><img class=\"aligncenter\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image13-6.png\" alt=\"315 to 195 KYA. Northern to eastern coasts of Africa are shaded.\" width=\"554\" height=\"428\" \/><\/p>\n<p class=\"import-Normal\"><img class=\"aligncenter\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image17-5.png\" alt=\"195-100 KYA. Africa, southern Europe and Asia are shaded\" width=\"554\" height=\"428\" \/><\/p>\n<p class=\"import-Normal\"><img class=\"aligncenter\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image27-3.png\" alt=\"99 to 30 KYA. Africa, Indonesia, Australia, and southern portions of Europe and Asia are shaded.\" width=\"554\" height=\"428\" \/><\/p>\n<figure style=\"width: 554px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image30-2.png\" alt=\"29 to 9 KYA. Shading covers most land except Antarctica, Greenland, and some islands.\" width=\"554\" height=\"428\" \/><figcaption class=\"wp-caption-text\">Figure 13.5a-d: Four maps depicting the estimated range of modern Homo sapiens through time. The shaded area is based on geographical connections across known sites. Note the growth in the area starting in Africa and the oftentimes-coastal routes that populations followed. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-14\/\" target=\"_blank\">Four maps depicting the estimated range of modern Homo sapiens through time<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Elyssa Ebding at <a href=\"https:\/\/www.csuchico.edu\/geop\/geoplace\/index.shtml\" target=\"_blank\">GeoPlace, California State University, Chico<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<h3 class=\"import-Normal\"><strong>Modern <\/strong><strong><em>Homo sapiens<\/em><\/strong><strong> Biology and Culture in Africa<\/strong><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">We start with the ample fossil evidence supporting the theory that modern humans originated in Africa during the Middle Pleistocene, having evolved from African archaic <em>Homo sapiens<\/em>. The earliest dated fossils considered to be modern actually have a mosaic of archaic and modern traits, showing the complex changes from one type to the other. Experts have various names for these transitional fossils, such as <strong><strong>Early Modern <\/strong><strong><em>Homo sapiens\u00a0 <\/em><\/strong> or Early Anatomically Modern Humans<\/strong>. However they are labeled, the presence of some modern traits means that they illustrate the origin of the modern type. Three particularly informative sites with fossils of the earliest modern <em>Homo sapiens<\/em> are Jebel Irhoud, Omo, and Herto.<\/p>\n<figure style=\"width: 281px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image9-1-1.jpg\" alt=\"3D image of a human cranium with pronounced brow ridges.\" width=\"281\" height=\"282\" \/><figcaption class=\"wp-caption-text\">Figure 13.6: Composite rendering of the Jebel Irhoud hominin based on micro-CT scans of multiple fossils from the site. The facial structure is within the modern human range, while the braincase is between the archaic and modern shapes. Credit: <a href=\"https:\/\/www.eva.mpg.de\/homo-sapiens\/presskit.html\" target=\"_blank\">A composite reconstruction of the earliest known Homo sapiens fossils from Jebel Irhoud (Morocco) based on micro computed tomographic scans<\/a> by Philipp Gunz, <a href=\"https:\/\/www.eva.mpg.de\/index.html\" target=\"_blank\">MPI EVA Leipzig<\/a>, is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/\" target=\"_blank\">CC BY-SA 2.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Recall from the start of the chapter that the most recent finds at Jebel Irhoud are now the oldest dated fossils that exhibit some facial traits of modern <em>Homo sapiens<\/em>. Besides Irhoud 10, the cranium that was dated to 315,000 years ago (Hublin Et al. 2017; Richter Et al. 2017), there were other fossils found in the same deposit that we now know are from the same time period. In total there are at least five individuals, representing life stages from childhood to adulthood. These fossils form an image of high variation in skeletal traits. For example, the skull named Irhoud 1 has a primitive brow ridge, while Irhoud 2 and Irhoud 10 do not (Figure 13.6). The braincases are lower than what is seen in the modern humans of today but higher than in archaic <em>Homo sapiens<\/em>. The teeth also have a mix of archaic and modern traits that defy clear categorization into either group.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Research separated by nearly four decades uncovered fossils and artifacts from the Kibish Formation in the Lower Omo Valley in Ethiopia. These Omo Kibish hominins were represented by braincases and fragmented postcranial bones of three individuals found kilometres apart, dating back to around 233,000 years ago (Day 1969; McDougall, Brown, and Fleagle 2005; Vidal Et al. 2022). One interesting finding was the variation in braincase size between the two more-complete specimens: while the individual named Omo I had a more globular dome, Omo II had an archaic-style long and low cranium.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Also in Ethiopia, a team led by Tim White (2003) excavated numerous fossils at Herto. There were fossilized crania of two adults and a child, along with fragments of more individuals. The dates ranged between 160,000 and 154,000 years ago. The skeletal traits and stone-tool assemblage were both intermediate between the archaic and modern types. Features reminiscent of modern humans included a tall braincase and thinner zygomatic (cheek) bones than those of archaic humans (Figure 13.7). Still, some archaic traits persisted in the Herto fossils, such as the supraorbital tori. Statistical analysis by other research teams concluded that at least some cranial measurements fit just within the modern human range (McCarthy and Lucas 2014), favouring categorization with our own species.<\/p>\n<figure style=\"width: 373px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image4-3.jpg\" alt=\"Replica cranium showing wide brow ridges and gracile face.\" width=\"373\" height=\"373\" \/><figcaption class=\"wp-caption-text\">Figure 13.7: This model of the Herto cranium showing its mosaic of archaic and modern traits. Credit: <a href=\"https:\/\/boneclones.com\/product\/homo-sapiens-idaltu-bou-vp-16-1-herto-skull-BH-045\/category\/all-fossil-hominids\/fossil-hominids\" target=\"_blank\">Homo sapiens idaltu BOU-VP-16\/1 Herto Cranium<\/a> by <a href=\"https:\/\/boneclones.com\/\" target=\"_blank\">\u00a9BoneClones<\/a> is used by permission and available here under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">The timeline of material culture suggests a long period of relying on similar tools before a noticeable diversification of artifacts types. Researchers label the time of stable technology shared with archaic types the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1766\"><strong>Middle Stone Age<\/strong><\/a>, while the subsequent time of diversification in material culture is called the<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1767\"> <strong>Later Stone Age<\/strong><\/a>.<\/p>\n<p class=\"import-Normal\">In the Middle Stone Age, the sites of Jebel Irhoud, Omo, and Herto all bore tools of the same flaked style as archaic assemblages, even though they were separated by almost 150,000 years. The consistency in technology may be evidence that behavioural modernity was not so developed. No clear signs of art dating back this far have been found either. Other hypotheses not related to behavioural modernity could explain these observations. The tool set may have been suitable for thriving in Africa without further innovation. Maybe works of art from that time were made with media that deteriorated or perhaps such art was removed by later humans.<\/p>\n<p class=\"import-Normal\">Evidence of what <em>Homo sapiens<\/em> did in Africa from the end of the Middle Stone Age to the Later Stone Age is concentrated in South African cave sites that reveal the complexity of human behaviour at the time. For example, Blombos Cave, located along the present shore of the Cape of Africa facing the Indian Ocean, is notable for having a wide variety of artifacts. The material culture shows that toolmaking and artistry were more complex than previously thought for the Middle Stone Age. In a layer dated to 100,000 years ago, researchers found two intact ochre-processing kits made of abalone shells and grinding stones (Henshilwood Et al. 2011). Marine snail shell beads from 75,000 years ago were also excavated (Figure 13.8; d\u2019Errico Et al. 2005). Together, the evidence shows that the Middle Stone Age occupation at Blombos Cave incorporated resources from a variety of local environments into their culture, from caves (ochre), open land (animal bones and fat), and the sea (abalone and snail shells). This complexity shows a deep knowledge of the region\u2019s resources and their use\u2014not just for survival but also for symbolic purposes.<\/p>\n<figure style=\"width: 563px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image5-2-1.jpg\" alt=\"Multiple views of shells with holes bored through them.\" width=\"563\" height=\"482\" \/><figcaption class=\"wp-caption-text\">Figure 13.8: Examples of the perforated shell beads found in Blombos Cave, South Africa: (a) view of carved hole seen from the inside; (b) arrows indicate worn surfaces due to repetitive contact with other objects, such as with other beads or a connecting string; (c) traces of ochre; and (d) four shell beads showing a consistent pattern of perforation. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:BBC-shell-beads.jpg\" target=\"_blank\">BBC-shell-beads<\/a> by Chenshilwood (Chris Henshilbood and Francesco d\u2019Errico) at <a href=\"https:\/\/en.wikipedia.org\/wiki\/\" target=\"_blank\">English Wikipedia<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">On the eastern coast of South Africa, Border Cave shows new African cultural developments at the start of the Later Stone Age. Paola Villa and colleagues (2012) identified several changes in technology around 43,000 years ago. Stone-tool production transitioned from a slower process to one that was faster and made many <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1777\">microliths<\/a><\/strong>, small and precise stone tools. Changes in decorations were also found across the Later Stone Age transition. Beads were made from a new resource: fragments of ostrich eggs shaped into circular forms resembling present-day breakfast cereal O\u2019s (d\u2019Errico Et al. 2012). These beads show a higher level of altering one\u2019s own surroundings and a move from the natural to the abstract in terms of design.<\/p>\n<h3 class=\"import-Normal\"><strong>Expansion into the Middle East and Asia<\/strong><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">While modern <em>Homo sapiens<\/em> lived across Africa, some members eventually left the continent. These pioneers could have used two connections to the Middle East or West Asia. From North Africa, they could have crossed the Sinai Peninsula and moved north to the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1769\"><strong>Levant<\/strong><\/a>, or eastern Mediterranean. Finds in that region show an early modern human presence. Other finds support the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1770\">Southern Dispersal model<\/a><\/strong>, with a crossing from East Africa to the southern Arabian Peninsula through the Straits of Bab-el-Mandeb. It is tempting to think of one momentous event in which people stepped off Africa and into the Middle East, never to look back. In reality, there were likely multiple waves of movement producing gene flow back and forth across these regions as the overall range pushed east. The expanding modern human population could have thrived by using resources along the southern coast of the Arabian Peninsula to South Asia, with side routes moving north along rivers. The maximum range of the species then grew across Asia.<\/p>\n<h4 class=\"import-Normal\"><em>Modern <\/em>Homo sapiens<em> in the Middle East<\/em><\/h4>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Geographically, the Middle East is the ideal place for the African modern <em>Homo sapiens<\/em> population to inhabit upon expanding out of their home continent. In the Eastern Mediterranean coast of the Levant, there is a wealth of skeletal and material culture linked to modern <em>Homo sapiens<\/em>. Recent discoveries from Saudi Arabia further add to our view of human life just beyond Africa.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The Caves of Mount Carmel in present-day Israel have preserved skeletal remains and artifacts of modern <em>Homo sapiens<\/em>, the first-known group living outside Africa. The skeletal presence at Misliya Cave is represented by just part of the left upper jaw of one individual, but it is notable for being dated to a very early time, between 194,000 and 177,000 years ago (Hershkovitz Et al. 2018). Later, from 120,000 to 90,000 years ago, fossils of multiple individuals across life stages were found in the caves of Es-Skhul and Qafzeh (Shea and Bar-Yosef 2005). The skeletons had many modern <em>Homo sapiens<\/em> traits, such as globular crania and more gracile postcranial bones when compared to Neanderthals. Still, there were some archaic traits. For example, the adult male Skhul V also possessed what researchers Daniel Lieberman, Osbjorn Pearson, and Kenneth Mowbray (2000) called marked or clear occipital bunning. Also, compared to later modern humans, the Mount Carmel people were more robust. Skhul V had a particularly impressive brow ridge that was short in height but sharply jutted forward above the eyes (Figure 13.9). The high level of preservation is due to the intentional burial of some of these people. Besides skeletal material, there are signs of artistic or symbolic behaviour. For example, the adult male Skhul V had a boar\u2019s jaw on his chest. Similarly, Qafzeh 11, a juvenile with healed cranial trauma, had an impressive deer antler rack placed over his torso (Figure 13.10; Coqueugniot Et al. 2014). Perforated seashells coloured with <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1806\"><strong>ochre<\/strong><\/a>, mineral-based pigment, were also found in Qafzeh (Bar-Yosef Mayer, Vandermeersch, and Bar-Yosef 2009).<\/p>\n<p>&nbsp;<\/p>\n<figure style=\"width: 484px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image6-2-1.jpg\" alt=\"Side view of a skull replica with a globular braincase.\" width=\"484\" height=\"484\" \/><figcaption class=\"wp-caption-text\">Figure 13.9: This Skhul V cranium model shows the sharp browridges. The contour of a marked occipital bun is barely visible from this angle. Credit: <a href=\"https:\/\/boneclones.com\/product\/homo-sapiens-skull-skhul-5-BH-032\" target=\"_blank\">Homo sapiens Skull Skhul 5<\/a> by <a href=\"https:\/\/boneclones.com\/\" target=\"_blank\">\u00a9BoneClones<\/a> is used by permission and available here under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<figure style=\"width: 484px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image26-1-1.jpg\" alt=\"Human skeleton in a stony matrix. Ribs are visible below the antlers.\" width=\"484\" height=\"312\" \/><figcaption class=\"wp-caption-text\">Figure 13.10 This cast of the Qafzeh 11 burial shows the antler\u2019s placement over the upper torso. The forearm bones appear to overlap the antler. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Moulage_de_la_s%C3%A9pulture_de_l&apos;individu_%22Qafzeh_11%22_(avec_ramure_de_cervid%C3%A9),_homme_de_N%C3%A9andertal.jpg\" target=\"_blank\">Moulage de la s\u00e9pulture de l'individu \"Qafzeh 11\" (avec ramure de cervid\u00e9), homme de N\u00e9andertal<\/a> (Collections du Mus\u00e9um national d'histoire naturelle de Paris, France) by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Eunostos\" target=\"_blank\">Eunostos<\/a> has been modified (cropped and colour modified) and is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\" target=\"_blank\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">One remaining question is, what happened to the modern humans of the Levant after 90,000 years ago? Another site attributed to our species did not appear in the region until 47,000 years ago. Competition with Neanderthals may have accounted for the disappearance of modern human occupation since the Neanderthal presence in the Levant lasted longer than the dates of the early modern <em>Homo sapiens<\/em>. John Shea and Ofer Bar-Yosef (2005) hypothesized that the Mount Carmel modern humans were an initial expansion from Africa that failed. Perhaps they could not succeed due to competition with the Neanderthals who had been there longer and had both cultural and biological adaptations to that environment.<\/p>\n<h4 class=\"import-Normal\"><em>Modern <\/em>Homo sapiens<em> of China<\/em><\/h4>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">A long history of paleoanthropology in China has found ample evidence of modern human presence. Four notable sites are the caves at Fuyan, Liujiang, Tianyuan, and Zhoukoudian. In the distant past, these caves would have been at least seasonal shelters that unintentionally preserved evidence of human presence for modern researchers to discover.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">At Fuyan Cave in Southern China, paleoanthropologists found 47 adult teeth associated with cave formations dated to between 120,000 and 80,000 years ago (Liu Et al. 2015). It is currently the oldest-known modern human site in China, though other researchers question the validity of the date range (Michel Et al. 2016). The teeth have the small size and gracile features of modern <em>Homo sapiens<\/em> dentition.<\/p>\n<p class=\"import-Normal\">The fossil Liujiang (or Liukiang) hominin (67,000 years ago) has derived traits that classified it as a modern <em>Homo sapiens<\/em>, though primitive archaic traits were also present. In the skull, which was found nearly complete, the Liujiang hominin had a taller forehead than archaic <em>Homo sapiens<\/em> but also had an enlarged occipital region (Figure 13.11; Brown 1999; Wu Et al. 2008). Other parts of the skeleton also had a mix of modern and archaic traits: for example, the femur fragments suggested a slender length but with thick bone walls (Woo 1959).<\/p>\n<p>&nbsp;<\/p>\n<figure style=\"width: 486px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image19-1-2.jpg\" alt=\"A human skull with very slight brow ridges and an extremely globular braincase.\" width=\"486\" height=\"323\" \/><figcaption class=\"wp-caption-text\">Figure 13.11: The Liujiang cranium shows the tall forehead and overall gracile appearance typical of modern Homo sapiens. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Liujiang_cave_skull-a._Homo_Sapiens_68,000_Years_Old.jpg\" target=\"_blank\">Liujiang cave skull-a. Homo Sapiens 68,000 Years Old<\/a> (Taken at the David H. Koch Hall of Human Origins, <a href=\"https:\/\/naturalhistory.si.edu\/visit\" target=\"_blank\">Smithsonian Natural History Museum<\/a>) by <a href=\"https:\/\/www.flickr.com\/people\/14405058@N08\" target=\"_blank\">Ryan Somma<\/a> has been modified (colour modified) and is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\" target=\"_blank\">CC BY-SA 2.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Another Chinese site to describe here is the one that has been studied the longest. In the Zhoukoudian Cave system (Figure 13.12), where <em>Homo erectus<\/em> and archaic <em>Homo sapiens<\/em> have also been found, there were three crania of modern <em>Homo sapiens<\/em>. These crania, which date to between 34,000 and 10,000 years ago, were all more globular than those of archaic humans but still lower and longer than those of later modern humans (Brown 1999; Harvati 2009). When compared to one another, the crania showed significant differences from one another. Comparison of cranial measurements to other populations past and present found no connection with modern East Asians, again showing that human variation was very different from what we see today.<\/p>\n<p>&nbsp;<\/p>\n<figure style=\"width: 610px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image12-1.jpg\" alt=\"A cave opening amongst a dry wooded region.\" width=\"610\" height=\"458\" \/><figcaption class=\"wp-caption-text\">Figure 13.12: The entrance to the Upper Cave of the Zhoukoudian complex, where crania of three ancient modern humans were found. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Zhoukoudian_Upper_Cave.jpg\" target=\"_blank\">Zhoukoudian Upper Cave<\/a> by Mutt is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\" target=\"_blank\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<h3 class=\"import-Normal\"><strong>Crossing to Australia<\/strong><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Expansion of the first modern human Asians, still following the coast, eventually entered an area that researchers call <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1772\">Sunda<\/a><\/strong> before continuing on to modern Australia. Sunda was a landmass made up of the modern-day Malay Peninsula, Sumatra, Java, and Borneo. Lowered sea levels connected these places with land bridges, making them easier to traverse. Proceeding past Sunda meant navigating <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1773\">Wallacea<\/a><\/strong>, the archipelago that includes the Indonesian islands east of Borneo. In the distant past, there were many <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_864\">megafauna<\/a><\/strong>, large animals that migrating humans would have used for food and materials (such as utilizing animals\u2019 hides and bones). Further southeast was another landmass called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1774\">Sahul<\/a><\/strong>, which included New Guinea and Australia as one contiguous continent. Based on fossil evidence, this land had never seen hominins or any other primates before modern <em>Homo sapiens<\/em> arrived. Sites along this path offer clues about how our species handled the new environment to live successfully as foragers.<\/p>\n<figure style=\"width: 380px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image18-1-1.jpg\" alt=\"A cranium showing a diagonal sloping forehead.\" width=\"380\" height=\"252\" \/><figcaption class=\"wp-caption-text\">Figure 13.13: Replica of the Kow Swamp 1 cranium. The shape of the braincase could be due to artificial cranial modification. A competing hypothesis is that it reflects the primitive shape of Homo erectus. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Kow_Swamp1-Homo_sapiens.jpg\" target=\"_blank\">Kow Swamp1-Homo sapiens<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/14405058@N08\" target=\"_blank\">Ryan Somma<\/a> from Occoquan, USA, under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\" target=\"_blank\">CC BY-SA 2.0 License<\/a> has been modified (background cleaned and colour modified) and is available here under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The skeletal remains at Lake Mungo, land traditionally owned by Mutthi Mutthi, Ngiampaa, and Paakantji peoples, are the oldest known in the continent. The now-dry lake was one of a series located along the southern coast of Australia in New South Wales, far from where the first people entered from the north (Barbetti and Allen 1972; Bowler Et al. 1970). Two individuals dating to around 40,000 years ago show signs of artistic and symbolic behaviour, including intentional burial. The bones of Lake Mungo 1 (LM1), an adult female, were crushed repeatedly, coloured with red ochre, and cremated (Bowler Et al. 1970). Lake Mungo 3 (LM3), a tall, older male with a gracile cranium but robust postcranial bones, had his fingers interlocked over his pelvic region (Brown 2000).<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Kow Swamp, within traditional Yorta Yorta land also in southern Australia, contained human crania that looked distinctly different from the ones at Lake Mungo (Durband 2014; Thorne and Macumber 1972). The crania, dated between 9,000 and 20,000 years ago, had extremely robust brow ridges and thick bone walls, but these were paired with globular features on the braincase (Figure 13.13).<\/p>\n<p class=\"import-Normal\">While no fossil humans have been found at the Madjedbebe rock shelter in the North Territory of Australia, more than 10,000 artifacts found there show both behavioural modernity and variability (Clarkson Et al. 2017). They include a diverse array of stone tools and different shades of ochre for rock art, including mica-based reflective pigment (similar to glitter). These impressive artifacts are as far back as 56,000 years old, providing the date for the earliest-known presence of humans in Australia.<\/p>\n<h3 class=\"import-Normal\"><strong>From the Levant to Europe<\/strong><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The first modern human expansion into Europe occurred after other members of our species settled in East Asia and Australia. As the evidence from the Levant suggests, modern human movement to Europe may have been hampered by the presence of Neanderthals. <span style=\"margin: 0px;padding: 0px\">It is suggested that another obstacle was the colder climate, which was incompatible with the biology of modern <em>Homo sapiens<\/em> from Africa, as they were adapted to high temperatures and ultraviolet radiation.<\/span> Still, by 40,000 years ago, modern <em>Homo sapiens<\/em> had a detectable presence. This time was also the start of the Later Stone Age or <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1775\">Upper Paleolithic<\/a><\/strong>, when there was an expansion in cultural complexity. There is a wealth of evidence from this region due to a Western bias in research, the proximity of these findings to Western scientific institutions, and the desire of Western scientists to explore their own past.<\/p>\n<figure style=\"width: 323px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image11-3.jpg\" alt=\"Robust cranium with a gradually sloping forehead.\" width=\"323\" height=\"323\" \/><figcaption class=\"wp-caption-text\">Figure 13.14: This side view of the Oase 2 cranium shows the reduced brow ridges but also occipital bunning that is a sign that modern Homo sapiens interbred with Neanderthals. Credit: <a href=\"https:\/\/humanorigins.si.edu\/evidence\/human-fossils\/fossils\/oase-2\" target=\"_blank\">Oase 2<\/a> by James Di Loreto &amp; Donald H. Hurlbert, <a href=\"https:\/\/www.si.edu\/\" target=\"_blank\">Smithsonian<\/a> [exhibit: Human Evolution Evidence, Human Fossils] has been modified (sharpened) and <a href=\"https:\/\/www.si.edu\/termsofuse\" target=\"_blank\">is used for educational and non-commercial purposes as outlined by the Smithsonian.<\/a><\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">In Romania, the site of Pe\u0219tera cu Oase (Cave of Bones) had the oldest-known remains of modern <em>Homo sapiens<\/em> in Europe, dated to around 40,000 years ago (Trinkaus Et al. 2003a). Among the bones and teeth of many animals were the fragmented cranium of one person and the mandible of another (the two bones did not fit each other). Both bones have modern human traits similar to the fossils from the Middle East, but they also had Neanderthal traits. Oase 1, the mandible, had a mental eminence but also extremely large molars (Trinkaus Et al. 2003b). This mandible has yielded DNA that surprisingly is equally similar to DNA from present-day Europeans and Asians (Fu Et al. 2015). This means that Oase 1 was not the direct ancestor of modern Europeans. The Oase 2 cranium has the derived traits of reduced brow ridges along with archaic wide zygomatic cheekbones and an occipital bun (Figure 13.14; Rougier Et al. 2007).<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Dating to around 26,000 years ago, P\u0159edmost\u00ed near P\u0159erov in the Czech Republic was a site where people buried over 30 individuals along with many artifacts. Eighteen individuals were found in one mass burial area, a few covered by the scapulae of woolly mammoths (Germonpr\u00e9, L\u00e1zni\u010dkov\u00e1-Galetov\u00e1, and Sablin 2012). The P\u0159edmost\u00ed crania were more globular than those of archaic humans but tended to be longer and lower than in later modern humans (Figure 13.15; Velem\u00ednsk\u00e1 Et al. 2008). The height of the face was in line with modern residents of Central Europe. There was also skeletal evidence of dog domestication, such as the presence of dog skulls with shorter snouts than in wild wolves (Germonpr\u00e9, L\u00e1zni\u010dkov\u00e1-Galetov\u00e1, and Sablin Et al. 2012). In total, P\u0159edmost\u00ed could have been a settlement dependent on mammoths for subsistence and the artificial selection of early domesticated dogs.<\/p>\n<figure style=\"width: 423px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image25-3.png\" alt=\"Black-and-white photograph of a human skull with labeled cranial landmarks.\" width=\"423\" height=\"389\" \/><figcaption class=\"wp-caption-text\">Figure 13.15: This illustration is based upon one of the surviving photographic negatives since the original fossil was lost in World War II. The modern human chin is prominent, as is an archaic occipital bun. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:P%C5%99edmost%C3%AD_9.png\" target=\"_blank\">P\u0159edmost\u00ed 9<\/a> by J. Matiegka (1862\u20131941) has been modified (sharpened) and is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\" target=\"_blank\">public domain<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The sequence of modern <em>Homo sapiens<\/em> technological change in the Later Stone Age has been thoroughly dated and labeled by researchers working in Europe. Among them, the Gravettian tradition of 33,000 years to 21,000 years ago is associated with most of the known curvy female figurines, often assumed to be \u201cVenus\u201d figures. Hunting technology also advanced in this time with the first known boomerang, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1792\"><strong>atlatl<\/strong><\/a> (spear thrower), and archery. The Magdalenian tradition spread from 17,000 to 12,000 years ago. This culture further expanded on fine bone tool work, including barbed spearheads and fishhooks (Figure 13.16).<\/p>\n<figure style=\"width: 511px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image2-1-1.jpg\" alt=\"Long, thin spear tips. Many have barbs, others are smooth.\" width=\"511\" height=\"494\" \/><figcaption class=\"wp-caption-text\">Figure 13.16: This drawing from 1891 shows an array of Magdalenian-style barbed points found in the burial of a reindeer hunter. They were carved from antler. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:La_station_quaternaire_de_Raymonden_(...)Hardy_Michel_bpt6k5567846s_(2).jpg\" target=\"_blank\">La station quaternaire de Raymonden (...)Hardy Michel bpt6k5567846s (2)<\/a> by M. F\u00e9auxis, original by Michel Hardy (1891), is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\" target=\"_blank\">public domain<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Among the many European sites dating to the Later Stone Age, the famous cave art sites deserve mention. Chauvet-Pont-d'Arc Cave in southern France dates to separate Aurignacian occupations 31,000 years ago and 26,000 years ago. Over a hundred art pieces representing 13 animal species are preserved, from commonly depicted deer and horses to rarer rhinos and owls. Another French cave with art is Lascaux, which is several thousand years younger at 17,000 years ago in the Magdalenian period. At this site, there are over 6,000 painted figures on the walls and ceiling (Figure 13.17). Scaffolding and lighting must have been used to make the paintings on the walls and ceiling deep in the cave. Overall, visiting Lascaux as a contemporary must have been an awesome experience: trekking deeper in the cave lit only by torches giving glimpses of animals all around as mysterious sounds echoed through the galleries.<\/p>\n<p>&nbsp;<\/p>\n<figure style=\"width: 605px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image24-2-1.jpg\" alt=\"Charcoal painting of a bull seen from the side.\" width=\"605\" height=\"454\" \/><figcaption class=\"wp-caption-text\">Figure 13.17: Photograph of just one surface with cave art at Lascaux Cave. The most prominent piece here is the Second Bull, found in a chamber called the Hall of Bulls. Smaller cattle and horses are also visible. Credit: <a href=\"https:\/\/whc.unesco.org\/en\/documents\/108435\" target=\"_blank\">Lascaux cave (document 108435) Prehitoric Sites and Decorated Caves of the V\u00e9z\u00e8re Valley (France)<\/a> by Francesco Bandarin, <a href=\"https:\/\/whc.unesco.org\/\" target=\"_blank\">\u00a9 UNESCO<\/a>, has been modified (colour modified) and is under a <a href=\"https:\/\/whc.unesco.org\/en\/licenses\/6\" target=\"_blank\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<div class=\"textbox shaded\" style=\"background: var(--lightblue)\">\n<h2>Special Topic: Cannibalism and Culture - Mortuary Practices in Modern Homo sapiens<\/h2>\n<p>Within a 2017 publication in the <em>Journal of Archaeological Method and Theory<\/em>, Saladi\u00e9 and Rodr\u00edguez-Hidalgo bring light to traces of early cannibalism in western Eurasia, arguing that context-specific cannibalistic practices were present throughout the Pleistocene and increased notably from the end of the Upper Palaeolithic and onward (Saladi\u00e9 &amp; Rodriguez-Hidalgo, 2017). While early hominins and Neandertals are recognized in this research, the authors highlight the presence of these mortuary practices in a cluster of <em>Homo sapiens<\/em> sites. More recent research uncovers similar findings that back these claims as well, where human bones in Herto Ethiopia, Maszycka Cave Poland, and Gough\u2019s Cave in the United Kingdom show anthropogenic defleshing and other modifications which have been interpreted as cannibalism (Pobiner, Et al. 2023). These findings suggest that cannibalistic behaviours formed a recurring aspect of modern human behaviour in certain ecological and cultural contexts.<\/p>\n<figure id=\"attachment_817-2\" aria-describedby=\"caption-attachment-817-2\" style=\"width: 378px\" class=\"wp-caption alignleft\"><img class=\" wp-image-817\" src=\"http:\/\/opentextbooks.concordia.ca\/explorationsversiontwo\/wp-content\/uploads\/sites\/71\/2023\/06\/d_-_briana_pobiner_-_figure_6.jpg\" alt=\"\" width=\"378\" height=\"369\" \/><figcaption id=\"caption-attachment-817-2\" class=\"wp-caption-text\">Figure 13.18: Close-up photos of three fossil animal specimens from the same area and time horizon as the fossil hominin tibia studied by the research team. These fossils show similar cut marks to those found on the hominin tibia studied. The photos show (a) an antelope mandible, (b) an antelope radius (lower front leg bone) and (c) a large mammal scapula (shoulder blade). Credit: <em data-start=\"617\" data-end=\"635\">23-199D Figure 6<\/em> by Smithsonian\u2019s National Museum of Natural History, from \"<a href=\"https:\/\/www.si.edu\/newsdesk\/releases\/humans-evolutionary-relatives-butchered-one-another-145-million-years-ago\" target=\"_blank\">Humans\u2019 Evolutionary Relatives Butchered One Another 1.45 Million Years Ago<\/a>,\" \u00a9 Smithsonian Institution, used with permission.<\/figcaption><\/figure>\n<p>A significant example comes from the Neolithic levels of Fontbr\u00e9gua Cave in southeastern France, where Paola Villa and colleagues compared clusters of human bones with the remains of wild and domestic animals from the same sediments. The study found that human bodies were butchered, processed, and most likely eaten in a way that parallels animal carcass treatment, including the placement and timing of cut marks, dismemberment sequences, and perimortem fractures to open marrow cavities (Villa, Et al. 1986). As the assemblage comes from a primary depositional context with pristine preservation and careful excavation, the authors suggest that cannibalism is the only satisfactory explanation for the pattern of cut marks and breakage seen on the human bones.<\/p>\n<p>More recent work has furthered this hypothesis for Late Upper Palaeolithic <em>Homo sapiens<\/em>, especially in Magdalenian contexts. In a 2023 study, researchers combined archeological and genetic evidence from fifty-nine Magdalenian sites, concluding that this specific culture shows an unusually high frequency of cannibalistic cases compared to earlier and later hominin groups; so much so that they identify \u201cprimary burial and cannibalism\u201d as the two main mortuary expressions (Marsh &amp; Bello, 2023). Additionally, new analyses from Maszycka Cave in Poland have described cut and broken human bones in patterns consistent with human consumption, reinforcing this cannibalism hypothesis (Marginedas &amp; Saladi\u00e9, 2025). Together, these studies suggest that for some Magdalenian groups, mortuary cannibalism was a habitual way of disposing of the dead, not just a one-off crisis response. At the same time, researchers emphasize that not every modified skeleton indicates blatant consumption of the dead and that ritual or symbolic perspectives must also be considered. Previously noted in chapter 12, Ullrich\u2019s survey of European mortuary practices presents frequent manipulations of corpses from the Palaeolithic through the Hallstatt period. Said manipulations include cut marks, dismemberment, skull fracturing, and marrow extraction (Ullrich, 2005, p. 258), which Ullrich interprets as cannibalistic rites embedded in cult ceremonies rather than everyday subsistence. In the author\u2019s view, some Palaeolithic groups may have believed that consuming members of their community allowed them to take on the strengths,<\/p>\n<figure id=\"attachment_819-2\" aria-describedby=\"caption-attachment-819-2\" style=\"width: 265px\" class=\"wp-caption alignright\"><img class=\"wp-image-819\" src=\"http:\/\/opentextbooks.concordia.ca\/explorationsversiontwo\/wp-content\/uploads\/sites\/71\/2023\/06\/a_-_briana_pobiner_-_figure_1.jpg\" alt=\"\" width=\"265\" height=\"379\" \/><figcaption id=\"caption-attachment-819-2\" class=\"wp-caption-text\">Figure 13.19: View of the hominin tibia and magnified area that shows cut marks. Scale = 4 cm. Credit: 23-199A Figure 1 by Jennifer Clark, Smithsonian Institution, from \"<a href=\"https:\/\/www.si.edu\/newsdesk\/releases\/humans-evolutionary-relatives-butchered-one-another-145-million-years-ago\" target=\"_blank\">Humans\u2019 Evolutionary Relatives Butchered One Another 1.45 Million Years Ago<\/a>,\" \u00a9Smithsonian Institution, used with permission.<\/figcaption><\/figure>\n<p>abilities, or even mental aspects of their dead member; the act of cannibalism may have functioned as a form of appropriating physical and mental powers rather than simply obtaining calories. With that, Neolithic assemblages show how careful taphonomic work can distinguish cuts linked to interpersonal violence from those associated with systemic butchery (Marginedas &amp; Saladi\u00e9, 2025). The findings seek to highlight that some <em>Homo sapiens<\/em> populations combined ritual, mortuary, and nutritional motives when processing human remains.<\/p>\n<p>These past and contemporary findings are significant for future anthropology students as they shed light on biological anthropology methodology and interpretation. Archaeologists are able to distinguish between occasions when humans were handled like any other carcass and times when they were handled in more symbolic ways thanks to factors like cut mark orientation, the timing of bone breakage, and direct comparison with animal remains. Readers interested in exploring this topic further should investigate the context-specific motivations for cannibalism, like nutritional stress, warfare, funerary sites, or ritual power appropriation.<\/p>\n<p>Similar archeological techniques have been used to explore behaviours of cannibalism among Indigenous Huron-Wendat populations in 1651 Canada, where human bones exhibit cutmarks, perimortem fractures, and thermal modifications (Spence &amp; Jackson, 2014). These shared taphonomic signatures across continents reveal recurring practices under ecological stress, bridging prehistoric Europe to North American contexts. Engaging with such analytical techniques opens up new ways that archeologists and anthropologists can investigate the variability in human behaviour, from nutritional crises to mortuary rituals.<\/p>\n<\/div>\n<h3 class=\"import-Normal\"><strong>Peopling of the Americas<\/strong><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">By 25,000 years ago, our species was the only member of <em>Homo<\/em> left on Earth. Gone were the Neanderthals, Denisovans, <em>Homo naledi,<\/em> and <em>Homo floresiensis<\/em>. The range of modern <em>Homo sapiens<\/em> kept expanding eastward into\u2014using the name given to this area by Europeans much later\u2014the Western Hemisphere. This section will address what we know about the peopling of the Americas, from the first entry to these continents to the rapid spread of Indigenous Americans across its varied environments.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">While evidence points to an ancient land bridge called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1778\"><strong>Beringia<\/strong><\/a> that allowed people to cross from what is now northeastern Siberia into modern-day Alaska, what people did to cross this land bridge is still being investigated. For most of the 20th century, the accepted theory was the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1779\"><strong>Ice-Free Corridor model<\/strong><\/a>. It stated that northeast Asians (East Asians and Siberians) first expanded across Beringia inland through a passage between glaciers that opened into the western Great Plains of the United States, just east of the Rocky Mountains, around 13,000 years ago (Swisher Et al. 2013). While life up north in the cold environment would have been harsh, migrating birds and an emerging forest might have provided sustenance as generations expanded through this land (Potter Et al. 2018).<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">However, in recent decades, researchers have accumulated evidence against the Ice-Free Corridor model. Archaeologist K. R. Fladmark (1979) brought the alternate <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1780\"><strong>Coastal Route model<\/strong><\/a> into the archaeological spotlight; researcher Jon M. Erlandson has been at the forefront of compiling support for this theory (Erlandson Et al. 2015). The new focus is the southern edge of the land bridge instead of its centre: About 16,000 years ago, members of our species expanded along the coastline from northeast Asia, east through Beringia, and south down the Pacific Coast of North America while the inland was still sealed off by ice. The coast would have been free of ice at least part of the year, and many resources would have been found there, such as fish (e.g., salmon), mammals (e.g., whales, seals, and otters), and plants (e.g., seaweed).<\/p>\n<h4 class=\"import-Normal\"><em>South through the Americas<\/em><\/h4>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">When the first modern <em>Homo sapiens<\/em> reached the Western Hemisphere, the spread through the Americas was rapid. Multiple migration waves crossed from North to South America (Posth Et al. 2018). Our species took advantage of the lack of hominin competition and the bountiful resources both along the coasts and inland. The Americas had their own wide array of megafauna, which included woolly mammoths (Figure 13.20), mastodons, camels, horses, ground sloths, giant tortoises, and\u2014a favourite of researchers\u2014a two-metre-tall beaver. The reason we cannot see these amazing animals today may be that resources gained from these fauna were crucial to the survival for people over 12,000 years ago (Araujo Et al. 2017). Several sites are notable for what they add to our understanding of the distant past in the Americas, including interactions with megafauna and other elements of the environment.<\/p>\n<figure style=\"width: 242px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image3-2-1.jpg\" alt=\"A mammoth model with long curving tusks.\" width=\"242\" height=\"323\" \/><figcaption class=\"wp-caption-text\">Figure 13.20: Life-size reconstruction of a woolly mammoth at the Page Museum, part of the La Brea Tar Pits complex in Los Angeles, California. Outside of Africa, megafauna such as this went extinct around the time that humans entered their range. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-14\/\" target=\"_blank\">Woolly Mammoth<\/a> (at <a href=\"https:\/\/tarpits.org\/\" target=\"_blank\">La Brea Tar Pits &amp; Museum<\/a>) by Keith Chan is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">A 2019 discovery may allow researchers to improve theories about the peopling of the Americas. In White Sands National Park, New Mexico, 60 human footprints have been astonishingly dated to around 22,000 years ago (Bennett Et al. 2021). This date and location do not match either the Ice-Free Corridor or Coastal Route models. Researchers are now working to verify the find and adjust previous models to account for the new evidence. This groundbreaking find is sparking new theories; it is another example of the fast pace of research performed on our past.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Monte Verde is a landmark site that shows that the human population had expanded down the whole vertical stretch of the Americas to Chile by 14,600 years ago. The site has been excavated by archaeologist Tom D. Dillehay and his team (2015). The remains of nine distinct edible species of seaweed at the site shows familiarity with coastal resources and relates to the Coastal Route model by showing a connection between the inland people and the sea.<\/p>\n<figure style=\"width: 254px\" class=\"wp-caption alignright\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image21-4.png\" alt=\"A long stone point with small chips around the edge.\" width=\"254\" height=\"362\" \/><figcaption class=\"wp-caption-text\">Figure 13.21: The Clovis point has a distinctive structure. It has a wide tip, and its base has two small projections. This example was carved from chert and found in north-central Ohio, dated to around 11,000 years ago. Credit: <a href=\"https:\/\/www.si.edu\/object\/chndm_15.2012.25\" target=\"_blank\">Clovis Point<\/a> (15.2012.25) by <a href=\"https:\/\/www.si.edu\/\" target=\"_blank\">the Smithsonian<\/a> [Department of Anthropology; Cooper Hewitt, Smithsonian Design Museum] <a href=\"https:\/\/www.si.edu\/termsofuse\" target=\"_blank\">is used for educational and non-commercial purposes as outlined by the Smithsonian.<\/a><\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Named after the town in New Mexico, the Clovis stone-tool style is the first example of a widespread culture across much of North America, between 13,400 and 12,700 years ago (Miller, Holliday, and Bright 2013). Clovis points were fluted with two small projections, one on each end of the base, facing away from the head (Figure 13.21). The stone points found at this site match those found as far as the Canadian border and northern Mexico, and from the west coast to the east coast of the United States. Fourteen Clovis sites also contained the remains of mammoths or mastodons, suggesting that hunting megafauna with these points was an important part of life for the Clovis people. After the spread of the Clovis style, it diversified into several regional styles, keeping some of the Clovis form but also developing their own unique touches.<\/p>\n<h3 class=\"import-Normal\"><strong>The Big Picture: The Assimilation Hypothesis<\/strong><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">How do researchers make sense of all of these modern <em>Homo sapiens<\/em> discoveries that cover over 300,000 years of time and stretch across every continent except Antarctica? How was modern <em>Homo sapiens<\/em> related to archaic <em>Homo sapiens<\/em>?<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1782\">Assimilation hypothesis<\/a><\/strong> proposes that modern <em>Homo sapiens<\/em> evolved in Africa first and expanded out but also interbred with the archaic <em>Homo sapiens<\/em> they encountered outside Africa (Figure 13.22). This hypothesis is powerful since it explains why Africa has the oldest modern human fossils, why early modern humans found in Europe and Asia bear a resemblance to the regional archaics, and why traces of archaic DNA can be found in our genomes today (Dannemann and Racimo 2018; Reich Et al. 2010; Reich Et al. 2011; Slatkin and Racimo 2016; Smith Et al. 2017; Wall and Yoshihara Caldeira Brandt 2016).<\/p>\n<figure style=\"width: 443px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image28-2.png\" alt=\"African Homo erectus expands and gives rise to archaics and modern Homo sapiens groups.\" width=\"443\" height=\"471\" \/><figcaption class=\"wp-caption-text\">Figure 13.22: This diagram shows archaic humans, having evolved from Homo erectus, expanded from Africa and established the Neanderthal and Denisovan groups. In Africa, archaic humans evolved modern traits and expanded from the continent as well, interbreeding with two archaic groups across Europe and Asia. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-14\/\" target=\"_blank\">Assimilation Model (Figure 12.23)l<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Keith Chan and Katie Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">While researchers have produced a model that satisfies the data, there are still a lot of questions for paleoanthropologists to answer regarding our origins. What were the patterns of migration in each part of the world? Why did the archaic humans go extinct? In what ways did archaic and modern humans interact? The definitive explanation of how our species started and what our ancestors did is still out there to be found. You are now in a great place to welcome the next discovery about our distant past\u2014maybe you\u2019ll even contribute to our understanding as well.<\/p>\n<h2 class=\"import-Normal\">The Chain Reaction of Agriculture<\/h2>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">While it may be hard to imagine today, for most of our species\u2019 existence we were nomadic: moving through the landscape without a singular home. Instead of a refrigerator or pantry stocked with food, we procured nutrition and other resources as needed based on what was available in the environment. This section gives an overview of how the foraging lifestyle enabled the expansion of our species and how the invention of a new way of life caused a chain reaction of cultural change.<\/p>\n<h3 class=\"import-Normal\"><strong>The Foraging Tradition<\/strong><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">There are a variety of possible <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1783\">subsistence strategies<\/a><\/strong>, or methods of finding sustenance and resources. To understand our species is to understand the subsistence strategy of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1114\">foraging<\/a><\/strong>, or the search for resources in the environment. While most (but not all) humans today live in cultures that practice <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1784\">agriculture<\/a> <\/strong>(whereby we greatly shape the environment to mass produce what we need), we have spent far more time as nomadic foragers than as settled agriculturalists. As such, it has been suggested that our traits have evolved to be primarily geared toward foraging. For instance, our efficient bipedalism allows persistence-hunting across long distances as well as movement from resource to resource.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">How does human foraging, also known as hunting and gathering, work? Anthropologists have used all four fields to answer this question (see Ember n.d.). Typically, people formed <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1785\"><strong>bands<\/strong><\/a>, or kin-based groups of around 50 people or less (rarely over 100). A band\u2019s organization would be <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1786\"><strong>e<\/strong><strong>galitarian<\/strong><\/a>, with a flexible hierarchy based on an individual\u2019s age, level of experience, and relationship with others. Everyone would have a general knowledge of the skills assigned to their gender roles, rather than specializing in different occupations. A band would be able to move from place to place in the environment, using knowledge of the area to forage (Figure 13.23). In varied environments\u2014from savannas to tropical forests, deserts, coasts, and the Arctic circle\u2014people found sustenance needed for survival.<\/p>\n<p>&nbsp;<\/p>\n<figure style=\"width: 565px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image22.jpg\" alt=\"A hunter holding a bow is crouched among dry grass.\" width=\"565\" height=\"377\" \/><figcaption class=\"wp-caption-text\">Figure 13.23: A present-day San man in Namibia demonstrates hunting using archery. Anthropologists study the San today to learn about the persistence of foraging as a viable lifestyle, while noting how these cultures have changed over time and how they interact with other groups. Credit: <a href=\"https:\/\/www.flickr.com\/photos\/charlesfred\/2129551464\" target=\"_blank\">San hunter w\u0131th bow and arrow<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/charlesfred\/\" target=\"_blank\">CharlesFred<\/a> has been modified (colour modified) and is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\" target=\"_blank\">CC BY-NC-SA 2.0 License.<\/a><\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Humans made extensive use of the foraging subsistence strategy, but this lifestyle did have limitations. The ease of foraging depended on the richness of the environment. Due to the lack of storage, resources had to be dependably found when needed. While a bountiful environment would require just a few hours of foraging a day and could lead to a focus on one location, the level and duration of labour increased greatly in poor or unreliable environments. Labour was also needed to process the acquired resources, which contributed to the foragers\u2019 daily schedule (Crittenden and Schnorr 2017).<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The adaptations to foraging found in modern <em>Homo sapiens<\/em> may explain why our species became so successful both within Africa and in the rapid expansion around the world. Overcoming the limitations, each generation at the edge of our species\u2019s range would have found it beneficial to expand a little further, keeping contact with other bands but moving into unexplored territory where resources were more plentiful. The cumulative effect would have been the spread of modern <em>Homo sapiens<\/em> across continents and hemispheres.<\/p>\n<h2 class=\"import-Normal\"><strong>Why Agriculture?<\/strong><\/h2>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">After hundreds of thousands of years of foraging, some groups of people around 12,000 years ago started to practice agriculture. This transition, called the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1787\"><strong>Neolithic Revolution<\/strong>,<\/a> occurred at the start of the <strong>Holocene<\/strong> epoch. While the reasons for this global change are still being investigated, two likely co-occurring causes are a growing human population and natural global climate change.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Overcrowding could have affected the success of foraging in the environment, leading to the development of a more productive subsistence strategy (Cohen 1977). Foraging works best with low population densities since each band needs a lot of space to support itself. If too many people occupy the same environment, they deplete the area faster. The high population could exceed the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1788\">carrying capacity<\/a><\/strong>, or number of people a location can reliably support. Reaching carrying capacity on a global level due to growing population and limited areas of expansion would have been an increasingly pressing issue after the expansion through the major continents by 14,600 years ago.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">A changing global climate immediately preceded the transition to agriculture, so researchers have also explored a connection between the two events. Since the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1789\">Last Glacial Maximum<\/a><\/strong> of 23,000 years ago, the Earth slowly warmed. Then, from 13,000 to 11,700 years ago, the temperature in most of the Northern Hemisphere dropped suddenly in a phenomenon called the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1790\"><strong>Younger Dryas<\/strong>.<\/a> Glaciers returned in Europe, Asia, and North America. In Mesopotamia, which includes the Levant, the climate changed from warm and humid to cool and dry. The change would have occurred over decades, disrupting the usual nomadic patterns and subsistence of foragers around the world. The disruption to foragers due to the temperature shift could have been a factor in spurring a transition to agriculture. Researchers Gregory K. Dow and colleagues (2009) believe that foraging bands would have clustered in the new resource-rich places where people started to direct their labour to farming the limited area. After the Younger Dryas ended, people expanded out of the clusters with their agricultural knowledge (Figure 13.24).<\/p>\n<figure style=\"width: 570px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image7-6.png\" alt=\"Map shows that agriculture was invented in at least six parts of the world.\" width=\"570\" height=\"267\" \/><figcaption class=\"wp-caption-text\">Figure 13.24: The map shows the areas where agriculture was independently invented around the world and where they spread. Blue arrows show the spread of agriculture from these zones to other regions. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\">A full text description of this image is available<\/a>. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Centres_of_origin_and_spread_of_agriculture.svg\" target=\"_blank\">Centres of origin and spread of agriculture<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Joe_Roe\" target=\"_blank\">Joe Roe<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The double threat of the limitation of human continental expansion and the sudden global climate change may have placed bands in peril as more populations outpaced their environment\u2019s carrying capacity. Not only had a growing population may have led to increased competition with other bands, but environments worldwide had shifted to create more uncertainty. As such, it has been proposed that as people in different areas around the world faced this unpredictable situation, they became the independent inventors of agriculture.<\/p>\n<h2 class=\"import-Normal\"><strong>Agriculture around the World<\/strong><\/h2>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Due to global changes to the human experience starting from 12,000 years ago, it has been suggested that cultures with no knowledge of each other turned toward intensely farming their local resources (see Figure 13.24).\u00a0 It is proposed that the first farmers engaged in artificial selection of their domesticates to enhance useful traits over generations. The switch to agriculture took time and effort with no guarantee of success and constant challenges (e.g. fires, droughts, diseases, and pests). The regions with the most widespread impact in the face of these obstacles became the primary centres of agriculture (Figure 13.25; Fuller 2010):<\/p>\n<ul>\n<li class=\"import-Normal\" style=\"text-indent: 0pt\">Mesopotamia: The Fertile Crescent from the Tigris and Euphrates rivers through the Levant was where bands started to domesticate plants and animals around 12,000 years ago. The connection between the development of agriculture and the Younger Dryas was especially strong here. Farmed crops included wheat, barley, peas, and lentils. This was also where cattle, pigs, sheep, and goats were domesticated.<\/li>\n<li class=\"import-Normal\" style=\"text-indent: 0pt\">South and East Asia: Multiple regions across this land had varieties of rice, millet, and soybeans by 10,000 years ago. Pigs were farmed with no connection to Mesopotamia. Chickens were also originally from this region, bred for fighting first and food second.<\/li>\n<li class=\"import-Normal\" style=\"text-indent: 0pt\">New Guinea: Agriculture started here 10,000 years ago. Bananas, sugarcane, and taro were native to this island. Sweet potatoes were brought back from voyages to South America around the year C.E. 1000. No known animal farming occurred here.<\/li>\n<li class=\"import-Normal\" style=\"text-indent: 0pt\">Mesoamerica: Agriculture from Central Mexico to northern South America also occurred from 10,000 years ago; it was also only plant based. Maize was a crop bred from teosinte grass, which has become one of the global staples. Beans, squash, and avocados were also grown in this region.<\/li>\n<li class=\"import-Normal\" style=\"text-indent: 0pt\">The Andes: Starting around 8,000 years ago, local domesticated plants started with squash but later included potatoes, tomatoes, beans, and quinoa. Maize was brought down from Mesoamerica. The main farm animals were llamas, alpacas, and guinea pigs.<\/li>\n<li class=\"import-Normal\" style=\"text-indent: 0pt\">Sub-Saharan Africa: This region went through a change 5,000 years ago called the Bantu expansion. The Bantu agriculturalists were established in West Central Africa and then expanded south and east. Native varieties of rice, yams, millet, and sorghum were grown across this area. Cattle were also domesticated here.<\/li>\n<li class=\"import-Normal\" style=\"text-indent: 0pt\">Eastern North America: This region was the last major independent agriculture centre, from 4,000 years ago. Squash and sunflower are the produce from this region that are most known today, though sumpweed and pitseed goosefoot were also farmed. Hunting was still the main source of animal products.<\/li>\n<\/ul>\n<figure style=\"width: 482px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image23-1-1.jpg\" alt=\"Farmers plow a flooded field. Each plow is pulled by two oxen. \" width=\"482\" height=\"320\" \/><figcaption class=\"wp-caption-text\">Figure 13.25: Rice farmers in the present day using draft cattle to prepare their field. Credit: <a href=\"https:\/\/www.flickr.com\/photos\/ricephotos\/7554483250\" target=\"_blank\">Plowing muddy field using cattle<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/ricephotos\/\" target=\"_blank\">IRRI Photos<\/a> (International Rice Research Institute) has been modified (colour modified) and is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\" target=\"_blank\">CC BY-NC-SA 2.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">By 5,000 years ago, our species was well within the Neolithic Revolution. Agriculturalists spread to neighbouring parts of the world with their domesticates, further expanding the use of this subsistence strategy. From this point, the human species changed from being primarily foragers to primarily agriculturalists with skilled control of their environments. The planet changed from mostly unaffected by human presence to being greatly transformed by humans. The revolution took millennia, but it was a true revolution as our species\u2019 lifestyle was dramatically reshaped.<\/p>\n<h3 class=\"import-Normal\"><strong>Cultural Effects of Agriculture<\/strong><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The worldwide adoption of agriculture altered the course of human culture and history forever. The core change in human culture due to agriculture is the move toward not moving: rather than live a nomadic lifestyle, farmers had to remain in one area to tend to their crops and livestock. The term for living bound to a certain location is <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1793\">sedentarism<\/a><\/strong>. This led to new aspects of life that were uncommon among foragers: the construction of permanent shelters and agricultural infrastructure, such as fields and irrigation, plus the development of storage technology, such as pottery, to preserve extra resources in case of future instability.<\/p>\n<figure style=\"width: 359px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image20-1-1.jpg\" alt=\"Multistory buildings surrounding a greek-style plaza.\" width=\"359\" height=\"270\" \/><figcaption class=\"wp-caption-text\">Figure 13.26: View of downtown San Diego taken by the author at a shopping complex during a break from jury duty. Here, people live amongst structures that facilitate commerce, government, tourism, and art. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-14\/\" target=\"_blank\">Downtown San Diego (October 13, 2016; Figure 12.28)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Keith Chan is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\"> CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The high productivity of successful agriculture sparked further changes (Smith 2009). It is argued that since successful agriculture produced a much greater amount of food and other resources per unit of land compared to foraging, the population growth rate skyrocketed. The surplus of a bountiful harvest also provided insurance for harder times, reducing the risk of famine and bringing change to society as well. With a few farming households producing enough food to feed many others, people could start specializing in roles such as craftspeople, traders, religious figures, and artists, spurring innovation in these areas as people could now devote time and effort toward specific skills. These interdependent people would settle an area together for convenience, and over time, the growth of these settlements led to <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1794\">urbanization<\/a><\/strong>, the founding of cities that became the foci of human interaction (Figure 13.26).<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The formation of cities led to new issues that sparked the growth of further specializations, called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1795\">institutions<\/a><\/strong>. These are cultural constructs that exist beyond the individual and have wide control over a population. Leadership of these cities became hierarchical with different levels of rank and control. The stratification of society increased social inequality between those with more or less power over others. Under leadership, people built impressive <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1796\">monumental architecture<\/a><\/strong>, such as pyramids and palaces, that embodied the wealth and power of these early cities. Alliances could unite cities, forming the earliest states. In several regions of the world, state organization expanded into empires, wide-ranging political entities that covered a variety of cultures.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Urbanization brought new challenges as well. The concentration of sedentary peoples was ideal for infectious diseases to thrive since they could jump from person to person and even from livestock to person (Armelagos, Brown, and Turner 2005). While successful agriculture provided a large surplus of food to thwart famine, the food produced offered less diverse food sources than foragers\u2019 diets (Cohen and Armelagos 1984; Cohen and Crane-Kramer 2007). This shift in nutrition caused other diseases to flourish among those who adopted farming, such as dental cavities and malocclusion (the misalignment of teeth caused by soft, agricultural diets). The need to extract \u201cwisdom teeth\u201d or third molars seen in agricultural cultures today stems from this misalignment between the environment our ancestors adapted to and our lifestyles today.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">As the new disease trends show, the adoption of agriculture and the ensuing cultural changes were not entirely positive. It is also important to note that this is not an absolutely linear progression of human culture from simple to complex. In many cases, empires have collapsed and, in some cases, cities dispersed to low-density bands that rejected institutions. However, a global trend has emerged since the adoption of agriculture, wherein population and social inequality have increased, leading to the massive and influential nation-states of today.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The rise of states in Europe has a direct impact on many of this book\u2019s topics. Science started as a European cultural practice by the upper class that became a standardized way to study the world. Education became an institution to provide a standardized path toward producing and gaining knowledge. The scientific study of human diversity, embroiled in the race concept that still haunts us today, was connected to the European slave trade and colonialism.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Also starting in Europe, the Industrial Revolution of the 19th century turned cities into centres of mass manufacturing and spurred the rapid development of inventions (Figure 13.27). In the technologically interconnected world of today, human society has reached a new level of complexity with <strong>globalization<\/strong>. In this system, goods are mass-produced and consumed in different parts of the world, weakening the reliance on local farms and factories. The imbalanced relationship between consumers and producers of goods further increases economic inequality.<\/p>\n<p>&nbsp;<\/p>\n<figure style=\"width: 465px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image1-3.jpg\" alt=\"A yellow farm vehicle driving into crops in a field.\" width=\"465\" height=\"310\" \/><figcaption class=\"wp-caption-text\">Figure 13.27: This combine harvester can collect and process grain at a massive scale. Our food now commonly comes from enormous farms located around the world. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Combine_CR9060.jpeg\" target=\"_blank\">Combine CR9060<\/a> by Hertzsprung is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">As states based on agriculture and industry keep exerting influence on humanity today, there are people, like the Hadzabe of Tanzania, who continue to live a lifestyle centred on foraging. Due to the overwhelming force that agricultural societies exert, foragers today have been marginalized to live in the least habitable parts of the world\u2014the areas that are not conducive to farming, such as tropical rainforests, deserts, and the Arctic (Headland Et al. 1989). Foragers can no longer live in the abundant environments that humans would have enjoyed before the Neolithic Revolution. Interactions with agriculturalists are typically imbalanced, with trade and other exchanges heavily favouring the larger group. One of anthropology\u2019s important roles today is to intelligently and humanely manage equitable interactions between people of different backgrounds and levels of influence.<\/p>\n<div class=\"textbox\">\n<h2 class=\"import-Normal\">Special Topic: Indigenous Land Management<\/h2>\n<p class=\"import-Normal\">Insight into the lives of past modern humans has evolved as researchers revise previous theories and establish new connections with Indigenous knowledge holders.<\/p>\n<p class=\"import-Normal\">The outdated view of foraging held that people lived off of the land without leaving an impact on the environment. Accompanying this idea was anthropologist Marshall Sahlins\u2019s (1968) proposal that foragers were the \u201coriginal affluent society\u201d since they were meeting basic needs and achieving satisfaction with less work hours than agriculturalists and city-dwellers. This view countered an earlier idea that foragers were always on the brink of starvation. Sahlins\u2019s theory took hold in the public eye as an attractive counterpoint to our busy contemporary lives in which we strive to meet our endless wants.<\/p>\n<p class=\"import-Normal\">A fruitful type of study involving researchers collaborating with Indigenous experts has found that foragers did not just live off the land with minimal effort nor were they barely surviving in unchanging environments. Instead, they shaped the landscape to their needs using labour and strategies that were more subtle than what European colonizers and subsequent researchers were used to seeing. Research from two regions shows the latest developments in understanding Indigenous land management.<\/p>\n<p class=\"import-Normal\">In British Columbia, Canada, the bridging of scientific and Indigenous perspectives has shown that the forests of the region are not untouched wilderness but, rather, have been crafted by Indigenous peoples thousands of years ago. Forest gardens adjacent to archaeological sites show higher plant diversity than unmanaged places even after 150 years (Armstrong Et al. 2021). On the coast, 3,500-year-old archaeological sites are evidence of constructed clam gardens, according to Indigenous experts (Lepofsky Et al. 2015). Another project, in consultation with Elders of the T\u2019exelc (William Lakes First Nation) in British Columbia, introduced researchers to explanations of how forests were managed before the practice was disrupted by European colonialism (Copes-Gerbitz Et al. 2021). Careful management of controlled fires reduced the density of the forest to favour plants such as raspberries and allow easier movement through the landscape.<\/p>\n<p class=\"import-Normal\">Similarly, the study of landscapes in Australia, in consultation with Aboriginal Australians today, shows that areas previously considered wilderness by scientists were actually the result of controlling fauna and fires. The presence of grasslands with adjacent forests were purposely constructed to attract kangaroos for hunting (Gammage 2008). People also managed other animal and insect life, from emus to caterpillars. In Tasmania, a shift from productive grassland to wildfire-prone rainforest occurred after Aboriginal Australian land management was replaced by British colonial rule (Fletcher, Hall, and Alexander 2021). The site of Budj Bim of the Gunditjmara people has archaeological features of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1798\">aquaculture<\/a><\/strong>, or the farming of fish, that date back 6,600 years (McNiven Et al. 2012; McNiven Et al. 2015). These examples show that Indigenous knowledge of how to manipulate the environment may be invaluable at the state level, such as by creating an Aboriginal ranger program to guide modern land management.<\/p>\n<\/div>\n<h2 class=\"import-Normal\">The Future of Humanity<\/h2>\n<p class=\"import-Normal\">A common question stemming from understanding human evolution is: What will the genetic and biological traits of our species be hundreds of thousands of years in the future? When faced with this question, people tend to think of directional selection. Maybe our braincases will be even larger, resembling the large-headed and small-bodied aliens of science fiction (Figure 13.28). Or, our hands could be specialized for interacting with our touch-based technology with less risk of repetitive injury. These ideas do not stand up to scrutiny. Since natural selection is based on adaptations that increase reproductive success, any directional change must be due to a higher rate of producing successful offspring compared to other alleles. Larger brains and more agile fingers would be convenient to possess, but they do not translate into an increase in the underlying allele frequencies.<\/p>\n<figure style=\"width: 571px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image8-4.png\" alt=\"One human has typical features; the other has a tall braincase.\" width=\"571\" height=\"279\" \/><figcaption class=\"wp-caption-text\">Figure 13.28: Will we evolve toward even more globular brains? Actually, this trend is not likely to continue for our species. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-14\/\" target=\"_blank\">Hypothetical image of future human evolution (Figure 12.30)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Scientists are hesitant to professionally speculate on the unknowable, and we will never know what is in store for our species one thousand or one million years from now, but there are two trends in human evolution that may carry on into the future: increased genetic variation and a reduction in regional differences.<\/p>\n<p class=\"import-Normal\">Rather than a directional change, genetic variation in our species could expand. Our technology can protect us from extreme environments and pathogens, even if our biological traits are not tuned to handle these stressors. The rapid pace of technological advancement means that biological adaptations will become less and less relevant to reproductive success, so nonbeneficial genetic traits will be more likely to remain in the gene pool. Biological anthropologist Jay T. Stock (2008) views environmental stress as needing to defeat two layers of protection before affecting our genetics. The first layer is our cultural adaptations. Our technology and knowledge can reduce pressure on one\u2019s genotype to be \u201cjust right\u201d to pass to the next generation. The second defence is our flexible physiology, such as our acclimatory responses. Only stressors not handled by these powerful responses would then cause natural selection on our alleles. These shields are already substantial, and cultural adaptations will only keep increasing in strength.<\/p>\n<p class=\"import-Normal\">The increasing ability to travel far from one\u2019s home region means that there will be a mixing of genetic variation on a global level in the future of our species. In recent centuries, gene flow of people around the world has increased, creating admixture in populations that had been separated for tens of thousands of years. For skin colour, this means that populations all around the world could exhibit the whole range of skin colours, rather than the current pattern of decreasing melanin pigment farther from the equator. The same trend of intermixing would apply to all other traits, such as blood types. While our genetics will become more varied, the variation will be more intermixed instead of regionally isolated.<\/p>\n<p class=\"import-Normal\">Our distant descendants will not likely be dextrous ultraintellectuals; more likely, they will be a highly variable and mobile species supported by novel cultural adaptations that make up for any inherited biological limitations. Technology may even enable the editing of DNA directly, changing these trends. With the uncertainty of our future, these are just the best-educated guesses for now. Our future is open and will be shaped little by little by the environment, our actions, and the actions of our descendants.<\/p>\n<h2>Cultural Connections and Contemporary Implications<\/h2>\n<p>The expansion of <em>Homo sapiens<\/em> across the globe and the subsequent and increasingly complex societies they developed have fundamentally altered the relationship between humans and the natural world. Throughout this chapter, we have seen how cultural innovations\u2014agriculture, urbanization, and technological development\u2014enabled humans to modify the environment in ways that no previous hominin could. At this point, the cumulative changes by <em>Homo sapiens<\/em> have irreversibly changed the planet, and some anthropologists and Earth scientists argue that we have entered a new stage of Earth\u2019s history known as the <em>Anthropocene<\/em> (notably the Nobel Laureate Paul J. Crutzen, known as one of the forces in popularizing the term and his part in the <em>Montreal Protocol; <\/em>cf<em>. <\/em>United Nations, 1987; Steffen, 2021<\/p>\n<p>The Anthropocene (or <em>Human Epoch<\/em>) describes a period in which natural processes and human activities have become inseparable, such that the future of Earth's ecosystems and humanity are increasingly dependent on one another (Steffen, 2021). This proposed epoch emphasizes humans\u2019 role as a planetary force capable of reshaping Earth on multiple levels; landscapes are transformed by mining, dam construction, urban expansion, and resource extraction. With this, we are witnessing increasing extinction, the introduction of invasive species, and genetic modification of organisms and unlike earlier periods of human evolution, these changes are occurring simultaneously across the entire planet, affecting ecological systems on a global scale. Although the Anthropocene has been proposed as a new geological epoch beginning in the mid-twentieth century, it has been refused formal adoption within the Geological Time Scale It is generally considered as a part of the Holocene, where agriculture and pastoralism significantly changed the earth despite an argument from a working group in the IPCC (Waters, C 2016).<\/p>\n<p>Nevertheless, the concept of the Anthropocene places modern human societies in positions of unprecedented responsibility. Climate change is not experienced equally, with poverty and social inequality increasing the vulnerability to these challenges, framing the Anthropocene as an environmental concept and a biocultural one as well. Just as agriculture transformed human societies, the choices made by modern populations regarding energy use, technology, and resource management will shape the environments inhabited by future generations and the continued evolution of our species. The Anthropocene therefore reminds us that anthropology and other disciplines aide us in understanding the evolutionary past they are also essential for understanding humanity's role in shaping the future.<\/p>\n<h4>Discussion questions<\/h4>\n<ul>\n<li>How do you see humans shaping the Earth today? Which of these changes do you consider permanent, temporary, harmful, or beneficial?<\/li>\n<li>How might the Anthropocene affect humans as a species? Like other species affected by environmental change, do you think humans could face extinction, or will our ability to modify our environment allow us to adapt?<\/li>\n<li>If humans eventually become a multiplanetary species, would the Anthropocene simply continue beyond Earth? What might this mean for our relationship with the environments we inhabit?<\/li>\n<\/ul>\n<div class=\"textbox\">\n<h2 class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">Hominin Species Summary<\/span><\/h2>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 450pt\">\n<tbody>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Hominin<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">Modern<em> Homo sapiens<\/em><\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Dates<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">315,000 years ago to present<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Region(s)<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Starting in Africa, then expanding around the world<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Famous discoveries<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 1.5pt;text-indent: 0pt\"><span style=\"color: #000000\">Cro-Magnon individuals, discovered 1868 in Dordogne, France. Otzi the Ice Man, discovered 1991 in the Alps between Austria and Italy. Kennewick man, discovered 1996 in Washington state.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Brain size<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">1400 cc average<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Dentition<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">Extremely small with short cusps.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Cranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">An extremely globular brain case and gracile features throughout the cranium. The mandibular symphysis forms a chin at the anterior-most point.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Postcranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Gracile skeleton adapted for efficient bipedal locomotion at the expense of the muscular strength of most other large primates.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Culture<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Extremely extensive and varied culture with many spoken and written languages. Art is ubiquitous. Technology is broad in complexity and impact on the environment.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Other<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">The only living hominin. Chimpanzees and bonobos are the closest living relatives.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div class=\"textbox shaded\">\n<h2 class=\"import-Normal\">Summary<\/h2>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Modern <em>Homo sapiens<\/em> is the species that took the hominin lifestyle the furthest to become the only living member of that lineage. The largest factor that allowed us to persist while other hominins went extinct was likely our advanced ability to culturally adapt to a wide variety of environments. Our species, with its skeletal and behavioural traits, was well-suited to be generalist-specialists who successfully foraged across most of the world\u2019s environments. The biological basis of this adaptation was our reorganized brain that facilitated innovation in cultural adaptations and intelligence for leveraging our social ties and finding ways to acquire resources from the environment. As the brain\u2019s ability increased, it shaped the skull by reducing the evolutionary pressure to have large teeth and robust cranial bones to produce the modern <em>Homo sapiens<\/em> face.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Our ability to be generalist-specialists is seen in the geographical range that modern <em>Homo sapiens<\/em> covered in 300,000 years. In Africa, our species formed from multiregional gene flow that loosely connected archaic humans across the continent. People then expanded out to the rest of the continental Eurasia and even further to the Americas.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">For most of our species\u2019s existence, foraging was the general subsistence strategy within which people specialized to culturally adapt to their local environment. With omnivorousness and mobility, people found ways to extract and process resources, shaping the environment in return. When resource uncertainty hit the species, people around the world focused on agriculture to have a firmer control of sustenance. The new strategy shifted human history toward exponential growth and innovation, leading to our high dependence on cultural adaptations today.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">While a cohesive image of our species has formed in recent years, there is still much to learn about our past. The work of many driven researchers shows that there are amazing new discoveries made all the time that refine our knowledge of human evolution. Technological innovations such as DNA analysis enable scientists to approach lingering questions from new angles. The answers we get allow us to ask even more insightful questions that will lead us to the next revelation. Like the pink limestone strata at Jebel Irhoud, previous effort has taken us so far and you are now ready to see what the next layer of discovery holds.<\/p>\n<h2 class=\"import-Normal\">Review Questions<strong><br \/>\n<\/strong><\/h2>\n<ul>\n<li>What are the skeletal and behavioural traits that define modern <em>Homo sapiens<\/em>? What are the evolutionary explanations for its presence?<\/li>\n<li>What are some creative ways that researchers have learned about the past by studying fossils and artifacts?<\/li>\n<li>How do the discoveries mentioned in \u201cFirst Africa, Then the World\u201d fit the Assimilation model?<\/li>\n<li>What is foraging? What adaptations do we have for this subsistence strategy? Could you train to be a skilled forager?<\/li>\n<li>What are aspects of your life that come from dependence on agriculture and its cultural effects? Where did the ingredients of your favourite foods originate from?<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<h2 class=\"__UNKNOWN__\">Key Terms<\/h2>\n<div class=\"__UNKNOWN__\">\n<p class=\"import-Normal\"><strong>African multiregionalism<\/strong>: The idea that modern <em>Homo sapiens<\/em> evolved as a complex web of small regional populations with sporadic gene flow among them.<\/p>\n<p class=\"import-Normal\"><strong>Agriculture<\/strong>: The mass production of resources through farming and domestication.<\/p>\n<p class=\"import-Normal\"><strong>Aquaculture<\/strong>: The farming of fish using techniques such as trapping, channels, and artificial ponds.<\/p>\n<p class=\"import-Normal\"><strong>Assimilation <\/strong><strong>hypothesis<\/strong>: Current theory of modern human origins stating that the species evolved first in Africa and interbred with archaic humans of Europe and Asia.<\/p>\n<p class=\"import-Normal\"><strong>Atlatl<\/strong>: A handheld spear thrower that increased the force of thrown projectiles.<\/p>\n<p class=\"import-Normal\"><strong>Band<\/strong>: A small group of people living together as foragers.<\/p>\n<p class=\"import-Normal\"><strong>Beringia<\/strong>: Ancient landmass that connected Siberia and Alaska. The ancestors of Indigenous Americans would have crossed this area to reach the Americas.<\/p>\n<p class=\"import-Normal\"><strong>Carrying capacity<\/strong>: The amount of organisms that an environment can reliably support.<\/p>\n<p class=\"import-Normal\"><strong>Coastal Route model<\/strong>: Theory that the first Paleoindians crossed to the Americas by following the southern coast of Beringia.<\/p>\n<p class=\"import-Normal\"><strong>Early Modern <\/strong><strong><em>Homo sapiens<\/em><\/strong><strong>, Early Anatomically Modern Human<\/strong>: Terms used to refer to transitional fossils between archaic and modern <em>Homo sapiens<\/em> that have a mosaic of traits. Humans like ourselves, who mostly lack archaic traits, are referred to as Late Modern <em>Homo sapiens<\/em> and simply Anatomically Modern Humans.<\/p>\n<p class=\"import-Normal\"><strong>Egalitarian<\/strong>: Human organization without strict ranks. Foraging societies tend to be more egalitarian than those based on other subsistence strategies.<\/p>\n<p class=\"import-Normal\"><strong>Foraging<\/strong>: Lifestyle consisting of frequent movement through the landscape and acquiring resources with minimal storage capacity.<\/p>\n<p class=\"import-Normal\"><strong>Generalist-specialist niche<\/strong>: The ability to survive in a variety of environments by developing local expertise. Evolution toward this niche may have been what allowed modern <em>Homo sapiens<\/em> to expand past the geographical range of other human species.<\/p>\n<p class=\"import-Normal\"><strong>Globalization<\/strong>: A recent increase in the interconnectedness and interdependence of people that is facilitated with long-distance networks.<\/p>\n<p class=\"import-Normal\"><strong>Globular<\/strong>: Having a rounded appearance. Increased globularity of the braincase is a trait of modern <em>Homo sapiens<\/em>.<\/p>\n<p class=\"import-Normal\"><strong>Gracile<\/strong>: Having a smooth and slender quality; the opposite of robust.<\/p>\n<p class=\"import-Normal\"><strong>Holocene<\/strong>: The epoch of the Cenozoic Era starting around 12,000 years ago and lasting arguably through the present.<\/p>\n<p class=\"import-Normal\"><strong>Ice-Free Corridor model<\/strong>: Theory that the first Native Americans crossed to the Americas through a passage between glaciers.<\/p>\n<p class=\"import-Normal\"><strong>Institutions<\/strong>: Long-lasting and influential cultural constructs. Examples include government, organized religion, academia, and the economy.<\/p>\n<p class=\"import-Normal\"><strong>Last Glacial Maximum<\/strong>: The time 23,000 years ago when the most recent ice age was the most intense.<\/p>\n<p class=\"import-Normal\"><strong>Later Stone Age<\/strong>: Time period following the Middle Stone Age with a diversification in tool types, starting around 50,000 years ago.<\/p>\n<p class=\"import-Normal\"><strong>Levant<\/strong>: The eastern coast of the Mediterranean. The site of early modern human expansion from Africa and later one of the centres of agriculture.<\/p>\n<p class=\"import-Normal\"><strong>Megafauna<\/strong>: Large ancient animals that may have been hunted to extinction by people around the world.<\/p>\n<p class=\"import-Normal\"><strong>Mental eminence<\/strong>: The chin on the mandible of modern <em>H. sapiens<\/em>. One of the defining traits of our species.<\/p>\n<p class=\"import-Normal\"><strong>Microlith<\/strong>: Small stone tool found in the Later Stone Age; also called a bladelet.<\/p>\n<p class=\"import-Normal\"><strong>Middle Stone Age<\/strong>: Time period known for Mousterian lithics that connects African archaic to modern <em>Homo sapiens<\/em>.<\/p>\n<p class=\"import-Normal\"><strong>Monumental architecture<\/strong>: Large and labour-intensive constructions that signify the power of the elite in a sedentary society. A common type is the pyramid, a raised crafted structure topped with a point or platform.<\/p>\n<p class=\"import-Normal\"><strong>Mosaic<\/strong>: Composed from a mix or composite of traits.<\/p>\n<p class=\"import-Normal\"><strong>Neolithic Revolution<\/strong>: Time of rapid change to human cultures due to the invention of agriculture, starting around 12,000 years ago.<\/p>\n<p class=\"import-Normal\"><strong>Ochre<\/strong>: Iron-based mineral pigment that can be a variety of yellows, reds, and browns. Used by modern human cultures worldwide since at least 80,000 years ago.<\/p>\n<p class=\"import-Normal\"><strong>Sahul<\/strong>: Ancient landmass connecting New Guinea and Australia.<\/p>\n<p class=\"import-Normal\"><strong>Sedentarism<\/strong>: Lifestyle based on having a stable home area; the opposite of nomadism.<\/p>\n<p class=\"import-Normal\"><strong>Southern Dispersal model<\/strong>: Theory that modern <em>H. sapiens<\/em> expanded from East Africa by crossing the Red Sea and following the coast east across Asia.<\/p>\n<p class=\"import-Normal\"><strong>Subsistence strategy<\/strong>: The method an organism uses to find nourishment and other resources.<\/p>\n<p class=\"import-Normal\"><strong>Sunda<\/strong>: Ancient Asian landmass that incorporated modern Southeast Asia.<\/p>\n<p class=\"import-Normal\"><strong>Supraorbital torus<\/strong>: The bony brow ridge across the top of the eye orbits on many hominin crania.<\/p>\n<p class=\"import-Normal\"><strong>Upper Paleolithic<\/strong>: Time period considered synonymous with the Later Stone Age.<\/p>\n<p class=\"import-Normal\"><strong>Urbanization<\/strong>: The increase of population density as people settled together in cities.<\/p>\n<p class=\"import-Normal\"><strong>Wallacea<\/strong>: Archipelago southeast of Sunda with different biodiversity than Asia.<\/p>\n<p class=\"import-Normal\"><strong>Younger Dryas<\/strong>: The rapid change in global climate\u2014notably a cooling of the Northern Hemisphere\u201413,000 years ago.<\/p>\n<h2 class=\"import-Normal\">For Further Exploration<\/h2>\n<h3 class=\"import-Normal\" style=\"text-indent: 0pt\"><strong>Websites<\/strong><\/h3>\n<p>First-person virtual tour of Lascaux cave with annotated cave art: Minist\u00e8re de la Culture and Mus\u00e9e d\u2019Arch\u00e9ologie Nationale. \u201c<a href=\"https:\/\/archeologie.culture.fr\/lascaux\/en\/visit-cave\" target=\"_blank\" rel=\"noopener\">Visit the cave<\/a>\u201d Lascaux website.<\/p>\n<p>Online anthropology magazine articles related to paleoanthropology and human evolution: SAPIENS. \u201c<a href=\"https:\/\/www.sapies.org\/category\/evolution\/\" target=\"_blank\" rel=\"noopener\">Evolution<\/a>.\u201d <em>SAPIENS<\/em> website.<\/p>\n<p>Various presentations of information about hominin evolution: Smithsonian Institution. \u201c<a href=\"https:\/\/humanorigins.si.edu\" target=\"_blank\" rel=\"noopener\">What does it mean to be human?<\/a>\u201d <em>Smithsonian National Museum of Natural History<\/em> website.<\/p>\n<p>Magazine-style articles on archaeology and paleoanthropology: ThoughtCo. \u201c<a href=\"https:\/\/www.thoughtco.com\/archaeology-4133504\" target=\"_blank\" rel=\"noopener\">Archaeology<\/a>.\u201d ThoughtCo. Website.<\/p>\n<p>Database of comparisons across hominins and primates: University of California, San Diego. \u201c<a href=\"https:\/\/carta.anthropogeny.org\/moca\/domains\" target=\"_blank\" rel=\"noopener\">MOCA Domains<\/a>.\u201d <em>Center for Academic Research &amp; Training in Anthropogeny<\/em> website.<\/p>\n<h3><strong>Books<\/strong><\/h3>\n<p>Engaging book that covers human-made changes to the environment with industrialization and globalization: Kolbert, Elizabeth. 2014. <em>The Sixth Extinction: An Unnatural History<\/em>. New York: Bloomsbury.<\/p>\n<p>Overview of what human life was like among the environmental shifts of the Ice Age: Woodward, Jamie. 2014. <em>The Ice Age: A Very Short Introduction<\/em>. Oxford: OUP Press.<\/p>\n<h3><strong>Articles<\/strong><\/h3>\n<p>Recent review paper about the current state of paleoanthropology research: Stringer, C. 2016. \u201c<a href=\"https:\/\/doi.org\/10.1098\/rstb.2015.0237\" target=\"_blank\" rel=\"noopener\">The Origin and Evolution of <em>Homo sapiens<\/em><\/a>.\u201d <em>Philosophical Transactions of the Royal Society B<\/em> 371 (1698).<\/p>\n<p>Overview of the history of American paleoanthropology and the many debates that have occurred over the years: Trinkaus, E. 2018. \u201cOne Hundred Years of Paleoanthropology: An American Perspective.\u201d <em>American Journal of Physical Anthropology<\/em> 165 (4): 638\u2013651.<\/p>\n<p>Amazing magazine article that synthesizes hominin evolution and why it is important to study this subject: Wheelwright, Jeff. 2015. \u201c<a href=\"https:\/\/discovermagazine.com\/2015\/may\/16-days-of-dysevolution\" target=\"_blank\" rel=\"noopener\">Days of Dysevolution<\/a>.\u201d <em>Discover<\/em> 36 (4): 33\u201339.<\/p>\n<p>Fascinating research on \u00d6tzi, a mummy from 5,000 years ago: Wierer, Ursula, Simona Arrighi, Stefano Bertola, G\u00fcnther Kaufmann, Benno Baumgarten, Annaluisa Pedrotti, Patrizia Pernter, and Jacques Pelegrin. 2018. \u201cThe Iceman\u2019s Lithic Toolkit: Raw Material, Technology, Typology and Use.\u201d <em>PLOS One<\/em> 13 (6): e0198292. https:\/\/doi.org\/10.1371\/journal.pone.0198292.<\/p>\n<h3><strong>Documentaries<\/strong><\/h3>\n<p>PBS NOVA series covering the expansion of modern <em>Homo sapiens<\/em> and interbreeding with archaic humans: Brown, Nicholas, dir. 2015. <em>First Peoples<\/em>. Edmonton: Wall to Wall Television. Amazon Prime Video.<\/p>\n<p>PBS NOVA special featuring the footprints found in White Sands National Park: Falk, Bella, dir. 2016. <em>Ice Age Footprints<\/em>. Boston: Windfall Films. https:\/\/www.pbs.org\/wgbh\/nova\/video\/ice-age-footprints\/.<\/p>\n<p>PBS NOVA special about how modern humans evolved adaptations to different environments. Shows how present-day people live around the world: Thompson, Niobe, dir. 2016. <em>Great Human Odyssey<\/em>. Edmonton: Clearwater Documentary. <a class=\"rId132\" href=\"https:\/\/www.pbs.org\/wgbh\/nova\/evolution\/great-human-odyssey.html\" target=\"_blank\">https:\/\/www.pbs.org\/wgbh\/nova\/evolution\/great-human-odyssey.html<\/a>.<\/p>\n<\/div>\n<h2 class=\"__UNKNOWN__\">References<\/h2>\n<div class=\"__UNKNOWN__\">\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Araujo, Bernardo B. A., Luiz Gustavo R. Oliveira-Santos, Matheus S. Lima-Ribeiro, Jos\u00e9 Alexandre F. 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Beaumont. 2012. \u201cEarly Evidence of San Material Culture Represented by Organic Artifacts from Border Cave, South Africa.\u201d <em>Proceedings of the National Academy of Sciences<\/em> 109 (33): 13214\u201313219.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">d\u2019Errico, Francesco, Christopher Henshilwood, Marian Vanhaeren, and Karen Van Niekerk. 2005. \u201cNassarius Kraussianus Shell Beads from Blombos Cave: Evidence for Symbolic Behaviour in the Middle Stone Age.\u201d <em>Journal of Human Evolution<\/em> 48 (1): 3\u201324.<\/p>\n<p class=\"import-Normal\">Dannemann, Michael, and Fernando Racimo. 2018. \u201cSomething Old, Something Borrowed: Admixture and Adaptation in Human Evolution.\u201d <em>Current Opinion in Genetics &amp; Development<\/em> 53: 1\u20138.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Day, M. 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Clark Howell. 2003. \u201cPleistocene <em>Homo sapiens<\/em> from Middle Awash, Ethiopia.\u201d <em>Nature<\/em> 423 (6941): 742\u2013747.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Woo, Ju-Kang. 1959. \u201cHuman Fossils Found in Liukiang, Kwangsi, China.\u201d <em>Vertebrata PalAsiatica<\/em> 3 (3): 109\u2013118.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Wu, XiuJie, Wu Liu, Wei Dong, JieMin Que, and YanFang Wang. 2008. \u201cThe Brain Morphology of Homo Liujiang Cranium Fossil by Three-Dimensional Computed Tomography.\u201d <em>Chinese Science Bulletin<\/em> 53 (16): 2513\u20132519.<\/p>\n<h2 class=\"import-Normal\">Acknowledgements<\/h2>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">I could not have undertaken this project without the help of many who got me to where I am today. I extend sincere thank yous to the many colleagues and former students who have inspired me to keep learning and talking about anthropology. Thank you also to all who are involved in this textbook project. The anonymous reviewers truly sparked improvements to the chapter. Lastly, the staff of Starbucks #5772 also contributed immensely to this text.<\/p>\n<\/div>\n<\/div>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1695_1882\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1695_1882\"><div tabindex=\"-1\"><div class=\"__UNKNOWN__\">\n<div class=\"textbox\">\n<h6>Student contributors to this chapter: Lily Berruyer, Lyn Loytchenko, and Sarah Cupidio<\/h6>\n<p>Learn more about <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/about-the-authors\/\">authors and editors<\/a>,<a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/student-contributors\/\"> Hess' student contributions<\/a>, and <a href=\"https:\/\/opentextbooks.concordia.ca\/explorations3\/back-matter\/versioning-history\/\">versioning history<\/a>.<\/p>\n<\/div>\n<div class=\"textbox textbox--learning-objectives\">\n<header class=\"textbox__header\">\n<h2 class=\"textbox__title\">Learning Objectives<\/h2>\n<\/header>\n<div class=\"textbox__content\">\n<ul>\n<li>Identify the skeletal and behavioural traits that represent modern <em>Homo sapiens.<\/em><\/li>\n<li>Critically evaluate different types of evidence for the origin of our species in Africa and our expansion around the world.<\/li>\n<li>Understand how the human lifestyle changed when people transitioned from foraging to agriculture.<\/li>\n<li>Hypothesize how human evolutionary trends may continue into the future.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<p class=\"import-Normal\">The walls of a pink limestone cave in the hillside of Jebel Irhoud jutted out of the otherwise barren landscape of the Moroccan desert (Figure 13.1). Miners had excavated the cave in the 1960s, revealing some fossils. In 2007, a re-excavation of the site became a momentous occasion for science. A fossil cranium unearthed by a team of researchers was barely visible to the untrained eye. Just the fossil\u2019s robust brows were peering out of the rock. This research team from the Max Planck Institute for Evolutionary Anthropology was the latest to explore the ancient human presence in this part of North Africa after a find by miners in 1960. Excavating near the first discovery, the researchers wanted to learn more about how <em>Homo sapiens<\/em> lived far from East Africa, where we thought our species originated.<\/p>\n<figure style=\"width: 2500px\" class=\"wp-caption alignnone\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2023\/06\/image10-1.jpg\" alt=\"Rocky hillside with exposed layers. People are visible at the base.\" width=\"2500\" height=\"987\" \/><figcaption class=\"wp-caption-text\">Figure 13.1: The excavation of an exposed cave at Jebel Irhoud, Morocco, where hominin fossils were found in the 1960s and in 2007. Dating showed that they could represent the earliest-known modern Homo sapiens. Credit: <a href=\"https:\/\/www.eva.mpg.de\/homo-sapiens\/presskit.html\" target=\"_blank\">View looking south of the Jebel Irhoud (Morocco) site<\/a> by Shannon McPherron, <a href=\"https:\/\/www.eva.mpg.de\/index.html\" target=\"_blank\">MPI EVA Leipzig<\/a>, is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/\" target=\"_blank\">CC BY-SA 2.0 License<\/a>.<\/figcaption><\/figure>\n<p>The scientists were surprised when they analysed the cranium, named Irhoud 10, and other fossils. Statistical comparisons with other human crania concluded that the Irhoud face shapes were typical of recent modern humans while the braincases matched ancient modern humans. Based on the findings of other scientists, the team expected these modern <em>Homo sapiens<\/em> fossils to be around 200,000 years old. Instead, dating revealed that the cranium had been buried for around 315,000 years.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Together, the modern-looking facial dimensions and the older date reshaped the interpretation of our species: modern <em>Homo sapiens<\/em>. Some key evolutionary changes from the archaic <em>Homo sapiens<\/em> (described in Chapter 12) to our species today happened 100,000 years earlier than we had thought and across the vast African continent rather than concentrated in its eastern region.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">This revelation in the study of modern <em>Homo sapiens<\/em> is just one of the latest in this continually advancing area of biological anthropology. Researchers today are still discovering amazing fossils and ingenious ways to collect data and test hypotheses about our past. Through the collective work of many scientists, we are building an overall theory of modern human origins.<\/p>\n<h2 class=\"import-Normal\">Defining Modernity<\/h2>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">What defines modern <em>Homo sapiens<\/em> when compared to archaic <em>Homo sapiens<\/em>? Modern humans, like you and me, have a set of derived traits that are not seen in archaic humans or any other hominin. As with other transitions in hominin evolution, such as increasing brain size and bipedal ability, modern traits do not appear fully formed or all at once. In other words, the first modern <em>Homo sapiens<\/em> was not just born one day from archaic parents. The traits common to modern <em>Homo sapiens<\/em> appeared in a <strong>mosaic<\/strong> manner: gradually and out of sync with one another. There are two areas to consider when tracking the complex evolution of modern human traits. One is the physical change in the skeleton. The other is behaviour inferred from the size and shape of the cranium and material culture evidence.<\/p>\n<h3 class=\"import-Normal\"><strong>Skeletal Traits<\/strong><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The skeleton of modern <em>Homo sapiens<\/em> is less robust than that of archaic <em>Homo sapiens<\/em>. In other words, the modern skeleton is <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1406\">gracile<\/a><\/strong>, meaning that the structures are thinner and smoother. Differences related to gracility in the cranium are seen in the braincase, the face, and the mandible. There are also broad differences in the rest of the skeleton.<\/p>\n<h4 class=\"import-Normal\"><em>Cranial Traits<\/em><\/h4>\n<figure style=\"width: 445px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image29-2.png\" alt=\"A rounded skull facing a robust skull with sloping forehead.\" width=\"445\" height=\"221\" \/><figcaption class=\"wp-caption-text\">Figure 13.2: Comparison between modern (left) and archaic (right) Homo sapiens skulls. Note the overall gracility of the modern skull, as well as the globular braincase. Credit: <a class=\"rId15\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-14\/\" target=\"_blank\">Modern human and Neanderthal<\/a> original to <a class=\"rId16\" href=\"https:\/\/explorations.americananthro.org\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a class=\"rId17\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Several elements of the braincase differ between modern and archaic <em>Homo sapiens<\/em>. Overall, the shape is much rounder, or more <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1758\"><strong>globular<\/strong>,<\/a> on a modern skull (Lieberman, McBratney, and Krovitz 2002; Neubauer, Hublin, and Gunz 2018; Pearson 2008; Figure 13.2). You can feel the globularity of your own modern human skull. Feel the height of your forehead with the palm of your hand. Viewed from the side, the tall vertical forehead of a modern <em>Homo sapiens<\/em> stands out when compared to the sloping archaic version. This is because the frontal lobe of the modern human brain is larger than the one in archaic humans, and the skull has to accommodate the expansion. The vertical forehead reduces a trait that is common to all other hominins: the brow ridge or <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1759\">supraorbital torus<\/a><\/strong>. The parietal lobes of the brain and the matching parietal bones on either side of the skull both bulge outward more in modern humans. At the back of the skull, the archaic occipital bun is no longer present. Instead, the occipital region of the modern human cranium has a derived tall and smooth curve, again reflecting the globular brain inside.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The trend of shrinking face size across hominins reaches its extreme with our species as well. The facial bones of a modern <em>Homo sapiens<\/em> are extremely gracile compared to all other hominins (Lieberman, McBratney, and Krovitz 2002). Continuing a trend in hominin evolution, technological innovations kept reducing the importance of teeth in reproductive success (Lucas 2007). As natural selection favoured smaller and smaller teeth, the surrounding bone holding these teeth also shrank.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Related to smaller teeth, the mandible is also gracile in modern humans when compared to archaic humans and other hominins. Interestingly, our mandibles have pulled back so far from the prognathism of earlier hominins that we gained an extra structure at the most anterior point, called the <strong>mental eminence<\/strong>. You know this structure as the chin. At the skeletal level, it resembles an upside-down \u201cT\u201d at the centreline of the mandible (Pearson 2008). Looking back at archaic humans, you will see that they all lack a chin. Instead, their mandibles curve straight back without a forward point. What is the chin for and how did it develop? Flora Gr\u00f6ning and colleagues (2011) found evidence of the chin\u2019s importance by simulating physical forces on computer models of different mandible shapes. Their results showed that the chin acts as structural support to withstand strain on the otherwise gracile mandible.<\/p>\n<h4 class=\"import-Normal\"><em>Postcranial Gracility<\/em><\/h4>\n<figure style=\"width: 368px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image16-5.png\" alt=\"Two complete skeletons. The left is taller with a thinner frame.\" width=\"368\" height=\"575\" \/><figcaption class=\"wp-caption-text\">Figure 13.3: Anterior views of modern (left) and archaic (right) Homo sapiens skeletons. The modern human has an overall gracile appearance at this scale as well. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-14\/\" target=\"_blank\">Modern and archaic Homo sapiens skeletons (Figure 12.3)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p>The rest of the modern human skeleton is also more gracile than its archaic counterpart. The differences are clear when comparing a modern <em>Homo sapiens<\/em> with a cold-adapted Neanderthal (Sawyer and Maley 2005), but the trends are still present when comparing modern and archaic humans within Africa (Pearson 2000). Overall, a modern <em>Homo sapiens<\/em> postcranial skeleton has thinner cortical bone, smoother features, and more slender shapes when compared to archaic <em>Homo sapiens<\/em> (Figure 13.3). Comparing whole skeletons, modern humans have longer limb proportions relative to the length and width of the torso, giving us lankier outlines.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Why is our skeleton so gracile compared to those of other hominins? Natural selection can drive the gracilization of skeletons in several ways (Lieberman 2015). A slender frame is believed to be adapted for the efficient long-distance running ability that started with <em>Homo erectus<\/em>. Furthermore, it is argued that slenderness is a genetic adaptation for cooling an active body in hotter climates, which aligns with the ample evidence that Africa was the home continent of our species.<\/p>\n<h3 class=\"import-Normal\"><strong>Behavioural Modernity<\/strong><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Aside from physical differences in the skeleton, researchers have also uncovered evidence of behavioural changes associated with increased cultural complexity from archaic to modern humans. How did cultural complexity develop? Two investigations into this question are archaeology and the analysis of reconstructed brains.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Archaeology tells us much about the behavioural complexity of past humans by interpreting the significance of material culture. In terms of advanced culture, items created with an artistic flair, or as decoration, speak of abstract thought processes (Figure 13.4). The demonstration of difficult artistic techniques and technological complexity hints at social learning and cooperation as well. According to paleoanthropologist John Shea (2011), one way to track the complexity of past behaviour through artifacts is by measuring the variety of tools found together. The more types of tools constructed with different techniques and for different purposes, the more modern the behaviour. Researchers are still working on an archaeological way to measure cultural complexity that is useful across time and place.<\/p>\n<figure style=\"width: 221px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image15-1-1.jpg\" alt=\"A brown standing statue of a human figure with cat\u2019s head.\" width=\"221\" height=\"392\" \/><figcaption class=\"wp-caption-text\">Figure 13.4: Carved ivory figure called \u201cthe Lion-Man of the Hohlenstein-Stadel.\u201d It dates to the Aurignacian culture, between 35 and 40 kya. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Loewenmensch1.jpg\" target=\"_blank\">Loewenmensch1<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Dagmar_Hollmann\" target=\"_blank\">Dagmar Hollmann<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The interpretation of brain anatomy is another promising approach to studying the evolution of human behaviour. When looking at investigations on this topic in modern <em>Homo sapiens<\/em> brains, researchers found a weak association between brain size and test-measured intelligence (Pietschnig Et al. 2015). Additionally, they found no association between intelligence and biological sex. These findings mean that there are more significant factors that affect tested intelligence than just brain size. Since the sheer size of the brain is not useful for weighing intelligence within a species, paleoanthropologists are instead investigating the differences in certain brain structures. The differences in organization between modern <em>Homo sapiens<\/em> brains and archaic <em>Homo sapiens<\/em> brains may reflect different cognitive priorities that account for modern human culture. As with the archaeological approach, new discoveries will refine what we know about the human brain and apply that knowledge to studying the distant past.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Taken together, the cognitive abilities in modern humans may have translated into an adept use of tools to enhance survival. Researchers Patrick Roberts and Brian A. Stewart (2018) call this concept the <strong>generalist-specialist niche<\/strong>: our species is an expert at living in a wide array of environments, with populations culturally specializing in their own particular surroundings. The next section tracks how far around the world these skeletal and behavioural traits have taken us.<\/p>\n<h2 class=\"import-Normal\">First Africa, Then the World<\/h2>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">What enabled modern <em>Homo sapiens<\/em> to expand its range further in 300,000 years than <em>Homo erectus<\/em> did in 1.5 million years? The key is the set of derived biological traits from the last section. It is theorized that the gracile frame and neurological anatomy allowed modern humans to survive and even flourish in the vastly different environments they encountered. Based on multiple types of evidence, the source of all of these modern humans was Africa. Instead of originating from just one location, evidence shows that modern Homo sapiens evolution occurred in a complex gene flow network across Africa, a concept called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1760\">African multiregionalism<\/a><\/strong> (Scerri Et al. 2018).<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">This section traces the origin of modern <em>Homo sapiens<\/em> and the massive expansion of our species across all of the continents (except Antarctica) by 12,000 years ago. While modern <em>Homo sapiens<\/em> first shared geography with archaic humans, modern humans eventually spread into lands where no human had gone before. Figure 13.5 shows the broad routes that our species took expanding around the world. I encourage you to make your own timeline with the dates in this part to see the overall trends.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\"><img class=\"aligncenter\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image13-6.png\" alt=\"315 to 195 KYA. Northern to eastern coasts of Africa are shaded.\" width=\"554\" height=\"428\" \/><\/p>\n<p class=\"import-Normal\"><img class=\"aligncenter\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image17-5.png\" alt=\"195-100 KYA. Africa, southern Europe and Asia are shaded\" width=\"554\" height=\"428\" \/><\/p>\n<p class=\"import-Normal\"><img class=\"aligncenter\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image27-3.png\" alt=\"99 to 30 KYA. Africa, Indonesia, Australia, and southern portions of Europe and Asia are shaded.\" width=\"554\" height=\"428\" \/><\/p>\n<figure style=\"width: 554px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image30-2.png\" alt=\"29 to 9 KYA. Shading covers most land except Antarctica, Greenland, and some islands.\" width=\"554\" height=\"428\" \/><figcaption class=\"wp-caption-text\">Figure 13.5a-d: Four maps depicting the estimated range of modern Homo sapiens through time. The shaded area is based on geographical connections across known sites. Note the growth in the area starting in Africa and the oftentimes-coastal routes that populations followed. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-14\/\" target=\"_blank\">Four maps depicting the estimated range of modern Homo sapiens through time<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Elyssa Ebding at <a href=\"https:\/\/www.csuchico.edu\/geop\/geoplace\/index.shtml\" target=\"_blank\">GeoPlace, California State University, Chico<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<h3 class=\"import-Normal\"><strong>Modern <\/strong><strong><em>Homo sapiens<\/em><\/strong><strong> Biology and Culture in Africa<\/strong><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">We start with the ample fossil evidence supporting the theory that modern humans originated in Africa during the Middle Pleistocene, having evolved from African archaic <em>Homo sapiens<\/em>. The earliest dated fossils considered to be modern actually have a mosaic of archaic and modern traits, showing the complex changes from one type to the other. Experts have various names for these transitional fossils, such as <strong><strong>Early Modern <\/strong><strong><em>Homo sapiens\u00a0 <\/em><\/strong> or Early Anatomically Modern Humans<\/strong>. However they are labeled, the presence of some modern traits means that they illustrate the origin of the modern type. Three particularly informative sites with fossils of the earliest modern <em>Homo sapiens<\/em> are Jebel Irhoud, Omo, and Herto.<\/p>\n<figure style=\"width: 281px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image9-1-1.jpg\" alt=\"3D image of a human cranium with pronounced brow ridges.\" width=\"281\" height=\"282\" \/><figcaption class=\"wp-caption-text\">Figure 13.6: Composite rendering of the Jebel Irhoud hominin based on micro-CT scans of multiple fossils from the site. The facial structure is within the modern human range, while the braincase is between the archaic and modern shapes. Credit: <a href=\"https:\/\/www.eva.mpg.de\/homo-sapiens\/presskit.html\" target=\"_blank\">A composite reconstruction of the earliest known Homo sapiens fossils from Jebel Irhoud (Morocco) based on micro computed tomographic scans<\/a> by Philipp Gunz, <a href=\"https:\/\/www.eva.mpg.de\/index.html\" target=\"_blank\">MPI EVA Leipzig<\/a>, is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/\" target=\"_blank\">CC BY-SA 2.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Recall from the start of the chapter that the most recent finds at Jebel Irhoud are now the oldest dated fossils that exhibit some facial traits of modern <em>Homo sapiens<\/em>. Besides Irhoud 10, the cranium that was dated to 315,000 years ago (Hublin Et al. 2017; Richter Et al. 2017), there were other fossils found in the same deposit that we now know are from the same time period. In total there are at least five individuals, representing life stages from childhood to adulthood. These fossils form an image of high variation in skeletal traits. For example, the skull named Irhoud 1 has a primitive brow ridge, while Irhoud 2 and Irhoud 10 do not (Figure 13.6). The braincases are lower than what is seen in the modern humans of today but higher than in archaic <em>Homo sapiens<\/em>. The teeth also have a mix of archaic and modern traits that defy clear categorization into either group.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Research separated by nearly four decades uncovered fossils and artifacts from the Kibish Formation in the Lower Omo Valley in Ethiopia. These Omo Kibish hominins were represented by braincases and fragmented postcranial bones of three individuals found kilometres apart, dating back to around 233,000 years ago (Day 1969; McDougall, Brown, and Fleagle 2005; Vidal Et al. 2022). One interesting finding was the variation in braincase size between the two more-complete specimens: while the individual named Omo I had a more globular dome, Omo II had an archaic-style long and low cranium.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Also in Ethiopia, a team led by Tim White (2003) excavated numerous fossils at Herto. There were fossilized crania of two adults and a child, along with fragments of more individuals. The dates ranged between 160,000 and 154,000 years ago. The skeletal traits and stone-tool assemblage were both intermediate between the archaic and modern types. Features reminiscent of modern humans included a tall braincase and thinner zygomatic (cheek) bones than those of archaic humans (Figure 13.7). Still, some archaic traits persisted in the Herto fossils, such as the supraorbital tori. Statistical analysis by other research teams concluded that at least some cranial measurements fit just within the modern human range (McCarthy and Lucas 2014), favouring categorization with our own species.<\/p>\n<figure style=\"width: 373px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image4-3.jpg\" alt=\"Replica cranium showing wide brow ridges and gracile face.\" width=\"373\" height=\"373\" \/><figcaption class=\"wp-caption-text\">Figure 13.7: This model of the Herto cranium showing its mosaic of archaic and modern traits. Credit: <a href=\"https:\/\/boneclones.com\/product\/homo-sapiens-idaltu-bou-vp-16-1-herto-skull-BH-045\/category\/all-fossil-hominids\/fossil-hominids\" target=\"_blank\">Homo sapiens idaltu BOU-VP-16\/1 Herto Cranium<\/a> by <a href=\"https:\/\/boneclones.com\/\" target=\"_blank\">\u00a9BoneClones<\/a> is used by permission and available here under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">The timeline of material culture suggests a long period of relying on similar tools before a noticeable diversification of artifacts types. Researchers label the time of stable technology shared with archaic types the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1766\"><strong>Middle Stone Age<\/strong><\/a>, while the subsequent time of diversification in material culture is called the<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1767\"> <strong>Later Stone Age<\/strong><\/a>.<\/p>\n<p class=\"import-Normal\">In the Middle Stone Age, the sites of Jebel Irhoud, Omo, and Herto all bore tools of the same flaked style as archaic assemblages, even though they were separated by almost 150,000 years. The consistency in technology may be evidence that behavioural modernity was not so developed. No clear signs of art dating back this far have been found either. Other hypotheses not related to behavioural modernity could explain these observations. The tool set may have been suitable for thriving in Africa without further innovation. Maybe works of art from that time were made with media that deteriorated or perhaps such art was removed by later humans.<\/p>\n<p class=\"import-Normal\">Evidence of what <em>Homo sapiens<\/em> did in Africa from the end of the Middle Stone Age to the Later Stone Age is concentrated in South African cave sites that reveal the complexity of human behaviour at the time. For example, Blombos Cave, located along the present shore of the Cape of Africa facing the Indian Ocean, is notable for having a wide variety of artifacts. The material culture shows that toolmaking and artistry were more complex than previously thought for the Middle Stone Age. In a layer dated to 100,000 years ago, researchers found two intact ochre-processing kits made of abalone shells and grinding stones (Henshilwood Et al. 2011). Marine snail shell beads from 75,000 years ago were also excavated (Figure 13.8; d\u2019Errico Et al. 2005). Together, the evidence shows that the Middle Stone Age occupation at Blombos Cave incorporated resources from a variety of local environments into their culture, from caves (ochre), open land (animal bones and fat), and the sea (abalone and snail shells). This complexity shows a deep knowledge of the region\u2019s resources and their use\u2014not just for survival but also for symbolic purposes.<\/p>\n<figure style=\"width: 563px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image5-2-1.jpg\" alt=\"Multiple views of shells with holes bored through them.\" width=\"563\" height=\"482\" \/><figcaption class=\"wp-caption-text\">Figure 13.8: Examples of the perforated shell beads found in Blombos Cave, South Africa: (a) view of carved hole seen from the inside; (b) arrows indicate worn surfaces due to repetitive contact with other objects, such as with other beads or a connecting string; (c) traces of ochre; and (d) four shell beads showing a consistent pattern of perforation. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:BBC-shell-beads.jpg\" target=\"_blank\">BBC-shell-beads<\/a> by Chenshilwood (Chris Henshilbood and Francesco d\u2019Errico) at <a href=\"https:\/\/en.wikipedia.org\/wiki\/\" target=\"_blank\">English Wikipedia<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">On the eastern coast of South Africa, Border Cave shows new African cultural developments at the start of the Later Stone Age. Paola Villa and colleagues (2012) identified several changes in technology around 43,000 years ago. Stone-tool production transitioned from a slower process to one that was faster and made many <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1777\">microliths<\/a><\/strong>, small and precise stone tools. Changes in decorations were also found across the Later Stone Age transition. Beads were made from a new resource: fragments of ostrich eggs shaped into circular forms resembling present-day breakfast cereal O\u2019s (d\u2019Errico Et al. 2012). These beads show a higher level of altering one\u2019s own surroundings and a move from the natural to the abstract in terms of design.<\/p>\n<h3 class=\"import-Normal\"><strong>Expansion into the Middle East and Asia<\/strong><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">While modern <em>Homo sapiens<\/em> lived across Africa, some members eventually left the continent. These pioneers could have used two connections to the Middle East or West Asia. From North Africa, they could have crossed the Sinai Peninsula and moved north to the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1769\"><strong>Levant<\/strong><\/a>, or eastern Mediterranean. Finds in that region show an early modern human presence. Other finds support the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1770\">Southern Dispersal model<\/a><\/strong>, with a crossing from East Africa to the southern Arabian Peninsula through the Straits of Bab-el-Mandeb. It is tempting to think of one momentous event in which people stepped off Africa and into the Middle East, never to look back. In reality, there were likely multiple waves of movement producing gene flow back and forth across these regions as the overall range pushed east. The expanding modern human population could have thrived by using resources along the southern coast of the Arabian Peninsula to South Asia, with side routes moving north along rivers. The maximum range of the species then grew across Asia.<\/p>\n<h4 class=\"import-Normal\"><em>Modern <\/em>Homo sapiens<em> in the Middle East<\/em><\/h4>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Geographically, the Middle East is the ideal place for the African modern <em>Homo sapiens<\/em> population to inhabit upon expanding out of their home continent. In the Eastern Mediterranean coast of the Levant, there is a wealth of skeletal and material culture linked to modern <em>Homo sapiens<\/em>. Recent discoveries from Saudi Arabia further add to our view of human life just beyond Africa.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The Caves of Mount Carmel in present-day Israel have preserved skeletal remains and artifacts of modern <em>Homo sapiens<\/em>, the first-known group living outside Africa. The skeletal presence at Misliya Cave is represented by just part of the left upper jaw of one individual, but it is notable for being dated to a very early time, between 194,000 and 177,000 years ago (Hershkovitz Et al. 2018). Later, from 120,000 to 90,000 years ago, fossils of multiple individuals across life stages were found in the caves of Es-Skhul and Qafzeh (Shea and Bar-Yosef 2005). The skeletons had many modern <em>Homo sapiens<\/em> traits, such as globular crania and more gracile postcranial bones when compared to Neanderthals. Still, there were some archaic traits. For example, the adult male Skhul V also possessed what researchers Daniel Lieberman, Osbjorn Pearson, and Kenneth Mowbray (2000) called marked or clear occipital bunning. Also, compared to later modern humans, the Mount Carmel people were more robust. Skhul V had a particularly impressive brow ridge that was short in height but sharply jutted forward above the eyes (Figure 13.9). The high level of preservation is due to the intentional burial of some of these people. Besides skeletal material, there are signs of artistic or symbolic behaviour. For example, the adult male Skhul V had a boar\u2019s jaw on his chest. Similarly, Qafzeh 11, a juvenile with healed cranial trauma, had an impressive deer antler rack placed over his torso (Figure 13.10; Coqueugniot Et al. 2014). Perforated seashells coloured with <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1806\"><strong>ochre<\/strong><\/a>, mineral-based pigment, were also found in Qafzeh (Bar-Yosef Mayer, Vandermeersch, and Bar-Yosef 2009).<\/p>\n<p>&nbsp;<\/p>\n<figure style=\"width: 484px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image6-2-1.jpg\" alt=\"Side view of a skull replica with a globular braincase.\" width=\"484\" height=\"484\" \/><figcaption class=\"wp-caption-text\">Figure 13.9: This Skhul V cranium model shows the sharp browridges. The contour of a marked occipital bun is barely visible from this angle. Credit: <a href=\"https:\/\/boneclones.com\/product\/homo-sapiens-skull-skhul-5-BH-032\" target=\"_blank\">Homo sapiens Skull Skhul 5<\/a> by <a href=\"https:\/\/boneclones.com\/\" target=\"_blank\">\u00a9BoneClones<\/a> is used by permission and available here under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<figure style=\"width: 484px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image26-1-1.jpg\" alt=\"Human skeleton in a stony matrix. Ribs are visible below the antlers.\" width=\"484\" height=\"312\" \/><figcaption class=\"wp-caption-text\">Figure 13.10 This cast of the Qafzeh 11 burial shows the antler\u2019s placement over the upper torso. The forearm bones appear to overlap the antler. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Moulage_de_la_s%C3%A9pulture_de_l&apos;individu_%22Qafzeh_11%22_(avec_ramure_de_cervid%C3%A9),_homme_de_N%C3%A9andertal.jpg\" target=\"_blank\">Moulage de la s\u00e9pulture de l'individu \"Qafzeh 11\" (avec ramure de cervid\u00e9), homme de N\u00e9andertal<\/a> (Collections du Mus\u00e9um national d'histoire naturelle de Paris, France) by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Eunostos\" target=\"_blank\">Eunostos<\/a> has been modified (cropped and colour modified) and is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\" target=\"_blank\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">One remaining question is, what happened to the modern humans of the Levant after 90,000 years ago? Another site attributed to our species did not appear in the region until 47,000 years ago. Competition with Neanderthals may have accounted for the disappearance of modern human occupation since the Neanderthal presence in the Levant lasted longer than the dates of the early modern <em>Homo sapiens<\/em>. John Shea and Ofer Bar-Yosef (2005) hypothesized that the Mount Carmel modern humans were an initial expansion from Africa that failed. Perhaps they could not succeed due to competition with the Neanderthals who had been there longer and had both cultural and biological adaptations to that environment.<\/p>\n<h4 class=\"import-Normal\"><em>Modern <\/em>Homo sapiens<em> of China<\/em><\/h4>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">A long history of paleoanthropology in China has found ample evidence of modern human presence. Four notable sites are the caves at Fuyan, Liujiang, Tianyuan, and Zhoukoudian. In the distant past, these caves would have been at least seasonal shelters that unintentionally preserved evidence of human presence for modern researchers to discover.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">At Fuyan Cave in Southern China, paleoanthropologists found 47 adult teeth associated with cave formations dated to between 120,000 and 80,000 years ago (Liu Et al. 2015). It is currently the oldest-known modern human site in China, though other researchers question the validity of the date range (Michel Et al. 2016). The teeth have the small size and gracile features of modern <em>Homo sapiens<\/em> dentition.<\/p>\n<p class=\"import-Normal\">The fossil Liujiang (or Liukiang) hominin (67,000 years ago) has derived traits that classified it as a modern <em>Homo sapiens<\/em>, though primitive archaic traits were also present. In the skull, which was found nearly complete, the Liujiang hominin had a taller forehead than archaic <em>Homo sapiens<\/em> but also had an enlarged occipital region (Figure 13.11; Brown 1999; Wu Et al. 2008). Other parts of the skeleton also had a mix of modern and archaic traits: for example, the femur fragments suggested a slender length but with thick bone walls (Woo 1959).<\/p>\n<p>&nbsp;<\/p>\n<figure style=\"width: 486px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image19-1-2.jpg\" alt=\"A human skull with very slight brow ridges and an extremely globular braincase.\" width=\"486\" height=\"323\" \/><figcaption class=\"wp-caption-text\">Figure 13.11: The Liujiang cranium shows the tall forehead and overall gracile appearance typical of modern Homo sapiens. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Liujiang_cave_skull-a._Homo_Sapiens_68,000_Years_Old.jpg\" target=\"_blank\">Liujiang cave skull-a. Homo Sapiens 68,000 Years Old<\/a> (Taken at the David H. Koch Hall of Human Origins, <a href=\"https:\/\/naturalhistory.si.edu\/visit\" target=\"_blank\">Smithsonian Natural History Museum<\/a>) by <a href=\"https:\/\/www.flickr.com\/people\/14405058@N08\" target=\"_blank\">Ryan Somma<\/a> has been modified (colour modified) and is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\" target=\"_blank\">CC BY-SA 2.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Another Chinese site to describe here is the one that has been studied the longest. In the Zhoukoudian Cave system (Figure 13.12), where <em>Homo erectus<\/em> and archaic <em>Homo sapiens<\/em> have also been found, there were three crania of modern <em>Homo sapiens<\/em>. These crania, which date to between 34,000 and 10,000 years ago, were all more globular than those of archaic humans but still lower and longer than those of later modern humans (Brown 1999; Harvati 2009). When compared to one another, the crania showed significant differences from one another. Comparison of cranial measurements to other populations past and present found no connection with modern East Asians, again showing that human variation was very different from what we see today.<\/p>\n<p>&nbsp;<\/p>\n<figure style=\"width: 610px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image12-1.jpg\" alt=\"A cave opening amongst a dry wooded region.\" width=\"610\" height=\"458\" \/><figcaption class=\"wp-caption-text\">Figure 13.12: The entrance to the Upper Cave of the Zhoukoudian complex, where crania of three ancient modern humans were found. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Zhoukoudian_Upper_Cave.jpg\" target=\"_blank\">Zhoukoudian Upper Cave<\/a> by Mutt is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\" target=\"_blank\">CC BY-SA 4.0 License<\/a>.<\/figcaption><\/figure>\n<h3 class=\"import-Normal\"><strong>Crossing to Australia<\/strong><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Expansion of the first modern human Asians, still following the coast, eventually entered an area that researchers call <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1772\">Sunda<\/a><\/strong> before continuing on to modern Australia. Sunda was a landmass made up of the modern-day Malay Peninsula, Sumatra, Java, and Borneo. Lowered sea levels connected these places with land bridges, making them easier to traverse. Proceeding past Sunda meant navigating <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1773\">Wallacea<\/a><\/strong>, the archipelago that includes the Indonesian islands east of Borneo. In the distant past, there were many <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_864\">megafauna<\/a><\/strong>, large animals that migrating humans would have used for food and materials (such as utilizing animals\u2019 hides and bones). Further southeast was another landmass called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1774\">Sahul<\/a><\/strong>, which included New Guinea and Australia as one contiguous continent. Based on fossil evidence, this land had never seen hominins or any other primates before modern <em>Homo sapiens<\/em> arrived. Sites along this path offer clues about how our species handled the new environment to live successfully as foragers.<\/p>\n<figure style=\"width: 380px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image18-1-1.jpg\" alt=\"A cranium showing a diagonal sloping forehead.\" width=\"380\" height=\"252\" \/><figcaption class=\"wp-caption-text\">Figure 13.13: Replica of the Kow Swamp 1 cranium. The shape of the braincase could be due to artificial cranial modification. A competing hypothesis is that it reflects the primitive shape of Homo erectus. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Kow_Swamp1-Homo_sapiens.jpg\" target=\"_blank\">Kow Swamp1-Homo sapiens<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/14405058@N08\" target=\"_blank\">Ryan Somma<\/a> from Occoquan, USA, under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\" target=\"_blank\">CC BY-SA 2.0 License<\/a> has been modified (background cleaned and colour modified) and is available here under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The skeletal remains at Lake Mungo, land traditionally owned by Mutthi Mutthi, Ngiampaa, and Paakantji peoples, are the oldest known in the continent. The now-dry lake was one of a series located along the southern coast of Australia in New South Wales, far from where the first people entered from the north (Barbetti and Allen 1972; Bowler Et al. 1970). Two individuals dating to around 40,000 years ago show signs of artistic and symbolic behaviour, including intentional burial. The bones of Lake Mungo 1 (LM1), an adult female, were crushed repeatedly, coloured with red ochre, and cremated (Bowler Et al. 1970). Lake Mungo 3 (LM3), a tall, older male with a gracile cranium but robust postcranial bones, had his fingers interlocked over his pelvic region (Brown 2000).<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Kow Swamp, within traditional Yorta Yorta land also in southern Australia, contained human crania that looked distinctly different from the ones at Lake Mungo (Durband 2014; Thorne and Macumber 1972). The crania, dated between 9,000 and 20,000 years ago, had extremely robust brow ridges and thick bone walls, but these were paired with globular features on the braincase (Figure 13.13).<\/p>\n<p class=\"import-Normal\">While no fossil humans have been found at the Madjedbebe rock shelter in the North Territory of Australia, more than 10,000 artifacts found there show both behavioural modernity and variability (Clarkson Et al. 2017). They include a diverse array of stone tools and different shades of ochre for rock art, including mica-based reflective pigment (similar to glitter). These impressive artifacts are as far back as 56,000 years old, providing the date for the earliest-known presence of humans in Australia.<\/p>\n<h3 class=\"import-Normal\"><strong>From the Levant to Europe<\/strong><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The first modern human expansion into Europe occurred after other members of our species settled in East Asia and Australia. As the evidence from the Levant suggests, modern human movement to Europe may have been hampered by the presence of Neanderthals. <span style=\"margin: 0px;padding: 0px\">It is suggested that another obstacle was the colder climate, which was incompatible with the biology of modern <em>Homo sapiens<\/em> from Africa, as they were adapted to high temperatures and ultraviolet radiation.<\/span> Still, by 40,000 years ago, modern <em>Homo sapiens<\/em> had a detectable presence. This time was also the start of the Later Stone Age or <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1775\">Upper Paleolithic<\/a><\/strong>, when there was an expansion in cultural complexity. There is a wealth of evidence from this region due to a Western bias in research, the proximity of these findings to Western scientific institutions, and the desire of Western scientists to explore their own past.<\/p>\n<figure style=\"width: 323px\" class=\"wp-caption alignleft\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image11-3.jpg\" alt=\"Robust cranium with a gradually sloping forehead.\" width=\"323\" height=\"323\" \/><figcaption class=\"wp-caption-text\">Figure 13.14: This side view of the Oase 2 cranium shows the reduced brow ridges but also occipital bunning that is a sign that modern Homo sapiens interbred with Neanderthals. Credit: <a href=\"https:\/\/humanorigins.si.edu\/evidence\/human-fossils\/fossils\/oase-2\" target=\"_blank\">Oase 2<\/a> by James Di Loreto &amp; Donald H. Hurlbert, <a href=\"https:\/\/www.si.edu\/\" target=\"_blank\">Smithsonian<\/a> [exhibit: Human Evolution Evidence, Human Fossils] has been modified (sharpened) and <a href=\"https:\/\/www.si.edu\/termsofuse\" target=\"_blank\">is used for educational and non-commercial purposes as outlined by the Smithsonian.<\/a><\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">In Romania, the site of Pe\u0219tera cu Oase (Cave of Bones) had the oldest-known remains of modern <em>Homo sapiens<\/em> in Europe, dated to around 40,000 years ago (Trinkaus Et al. 2003a). Among the bones and teeth of many animals were the fragmented cranium of one person and the mandible of another (the two bones did not fit each other). Both bones have modern human traits similar to the fossils from the Middle East, but they also had Neanderthal traits. Oase 1, the mandible, had a mental eminence but also extremely large molars (Trinkaus Et al. 2003b). This mandible has yielded DNA that surprisingly is equally similar to DNA from present-day Europeans and Asians (Fu Et al. 2015). This means that Oase 1 was not the direct ancestor of modern Europeans. The Oase 2 cranium has the derived traits of reduced brow ridges along with archaic wide zygomatic cheekbones and an occipital bun (Figure 13.14; Rougier Et al. 2007).<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Dating to around 26,000 years ago, P\u0159edmost\u00ed near P\u0159erov in the Czech Republic was a site where people buried over 30 individuals along with many artifacts. Eighteen individuals were found in one mass burial area, a few covered by the scapulae of woolly mammoths (Germonpr\u00e9, L\u00e1zni\u010dkov\u00e1-Galetov\u00e1, and Sablin 2012). The P\u0159edmost\u00ed crania were more globular than those of archaic humans but tended to be longer and lower than in later modern humans (Figure 13.15; Velem\u00ednsk\u00e1 Et al. 2008). The height of the face was in line with modern residents of Central Europe. There was also skeletal evidence of dog domestication, such as the presence of dog skulls with shorter snouts than in wild wolves (Germonpr\u00e9, L\u00e1zni\u010dkov\u00e1-Galetov\u00e1, and Sablin Et al. 2012). In total, P\u0159edmost\u00ed could have been a settlement dependent on mammoths for subsistence and the artificial selection of early domesticated dogs.<\/p>\n<figure style=\"width: 423px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image25-3.png\" alt=\"Black-and-white photograph of a human skull with labeled cranial landmarks.\" width=\"423\" height=\"389\" \/><figcaption class=\"wp-caption-text\">Figure 13.15: This illustration is based upon one of the surviving photographic negatives since the original fossil was lost in World War II. The modern human chin is prominent, as is an archaic occipital bun. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:P%C5%99edmost%C3%AD_9.png\" target=\"_blank\">P\u0159edmost\u00ed 9<\/a> by J. Matiegka (1862\u20131941) has been modified (sharpened) and is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\" target=\"_blank\">public domain<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The sequence of modern <em>Homo sapiens<\/em> technological change in the Later Stone Age has been thoroughly dated and labeled by researchers working in Europe. Among them, the Gravettian tradition of 33,000 years to 21,000 years ago is associated with most of the known curvy female figurines, often assumed to be \u201cVenus\u201d figures. Hunting technology also advanced in this time with the first known boomerang, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1792\"><strong>atlatl<\/strong><\/a> (spear thrower), and archery. The Magdalenian tradition spread from 17,000 to 12,000 years ago. This culture further expanded on fine bone tool work, including barbed spearheads and fishhooks (Figure 13.16).<\/p>\n<figure style=\"width: 511px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image2-1-1.jpg\" alt=\"Long, thin spear tips. Many have barbs, others are smooth.\" width=\"511\" height=\"494\" \/><figcaption class=\"wp-caption-text\">Figure 13.16: This drawing from 1891 shows an array of Magdalenian-style barbed points found in the burial of a reindeer hunter. They were carved from antler. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:La_station_quaternaire_de_Raymonden_(...)Hardy_Michel_bpt6k5567846s_(2).jpg\" target=\"_blank\">La station quaternaire de Raymonden (...)Hardy Michel bpt6k5567846s (2)<\/a> by M. F\u00e9auxis, original by Michel Hardy (1891), is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\" target=\"_blank\">public domain<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Among the many European sites dating to the Later Stone Age, the famous cave art sites deserve mention. Chauvet-Pont-d'Arc Cave in southern France dates to separate Aurignacian occupations 31,000 years ago and 26,000 years ago. Over a hundred art pieces representing 13 animal species are preserved, from commonly depicted deer and horses to rarer rhinos and owls. Another French cave with art is Lascaux, which is several thousand years younger at 17,000 years ago in the Magdalenian period. At this site, there are over 6,000 painted figures on the walls and ceiling (Figure 13.17). Scaffolding and lighting must have been used to make the paintings on the walls and ceiling deep in the cave. Overall, visiting Lascaux as a contemporary must have been an awesome experience: trekking deeper in the cave lit only by torches giving glimpses of animals all around as mysterious sounds echoed through the galleries.<\/p>\n<p>&nbsp;<\/p>\n<figure style=\"width: 605px\" class=\"wp-caption aligncenter\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image24-2-1.jpg\" alt=\"Charcoal painting of a bull seen from the side.\" width=\"605\" height=\"454\" \/><figcaption class=\"wp-caption-text\">Figure 13.17: Photograph of just one surface with cave art at Lascaux Cave. The most prominent piece here is the Second Bull, found in a chamber called the Hall of Bulls. Smaller cattle and horses are also visible. Credit: <a href=\"https:\/\/whc.unesco.org\/en\/documents\/108435\" target=\"_blank\">Lascaux cave (document 108435) Prehitoric Sites and Decorated Caves of the V\u00e9z\u00e8re Valley (France)<\/a> by Francesco Bandarin, <a href=\"https:\/\/whc.unesco.org\/\" target=\"_blank\">\u00a9 UNESCO<\/a>, has been modified (colour modified) and is under a <a href=\"https:\/\/whc.unesco.org\/en\/licenses\/6\" target=\"_blank\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<div class=\"textbox shaded\" style=\"background: var(--lightblue)\">\n<h2>Special Topic: Cannibalism and Culture - Mortuary Practices in Modern Homo sapiens<\/h2>\n<p>Within a 2017 publication in the <em>Journal of Archaeological Method and Theory<\/em>, Saladi\u00e9 and Rodr\u00edguez-Hidalgo bring light to traces of early cannibalism in western Eurasia, arguing that context-specific cannibalistic practices were present throughout the Pleistocene and increased notably from the end of the Upper Palaeolithic and onward (Saladi\u00e9 &amp; Rodriguez-Hidalgo, 2017). While early hominins and Neandertals are recognized in this research, the authors highlight the presence of these mortuary practices in a cluster of <em>Homo sapiens<\/em> sites. More recent research uncovers similar findings that back these claims as well, where human bones in Herto Ethiopia, Maszycka Cave Poland, and Gough\u2019s Cave in the United Kingdom show anthropogenic defleshing and other modifications which have been interpreted as cannibalism (Pobiner, Et al. 2023). These findings suggest that cannibalistic behaviours formed a recurring aspect of modern human behaviour in certain ecological and cultural contexts.<\/p>\n<figure id=\"attachment_817-3\" aria-describedby=\"caption-attachment-817-3\" style=\"width: 378px\" class=\"wp-caption alignleft\"><img class=\" wp-image-817\" src=\"http:\/\/opentextbooks.concordia.ca\/explorationsversiontwo\/wp-content\/uploads\/sites\/71\/2023\/06\/d_-_briana_pobiner_-_figure_6.jpg\" alt=\"\" width=\"378\" height=\"369\" \/><figcaption id=\"caption-attachment-817-3\" class=\"wp-caption-text\">Figure 13.18: Close-up photos of three fossil animal specimens from the same area and time horizon as the fossil hominin tibia studied by the research team. These fossils show similar cut marks to those found on the hominin tibia studied. The photos show (a) an antelope mandible, (b) an antelope radius (lower front leg bone) and (c) a large mammal scapula (shoulder blade). Credit: <em data-start=\"617\" data-end=\"635\">23-199D Figure 6<\/em> by Smithsonian\u2019s National Museum of Natural History, from \"<a href=\"https:\/\/www.si.edu\/newsdesk\/releases\/humans-evolutionary-relatives-butchered-one-another-145-million-years-ago\" target=\"_blank\">Humans\u2019 Evolutionary Relatives Butchered One Another 1.45 Million Years Ago<\/a>,\" \u00a9 Smithsonian Institution, used with permission.<\/figcaption><\/figure>\n<p>A significant example comes from the Neolithic levels of Fontbr\u00e9gua Cave in southeastern France, where Paola Villa and colleagues compared clusters of human bones with the remains of wild and domestic animals from the same sediments. The study found that human bodies were butchered, processed, and most likely eaten in a way that parallels animal carcass treatment, including the placement and timing of cut marks, dismemberment sequences, and perimortem fractures to open marrow cavities (Villa, Et al. 1986). As the assemblage comes from a primary depositional context with pristine preservation and careful excavation, the authors suggest that cannibalism is the only satisfactory explanation for the pattern of cut marks and breakage seen on the human bones.<\/p>\n<p>More recent work has furthered this hypothesis for Late Upper Palaeolithic <em>Homo sapiens<\/em>, especially in Magdalenian contexts. In a 2023 study, researchers combined archeological and genetic evidence from fifty-nine Magdalenian sites, concluding that this specific culture shows an unusually high frequency of cannibalistic cases compared to earlier and later hominin groups; so much so that they identify \u201cprimary burial and cannibalism\u201d as the two main mortuary expressions (Marsh &amp; Bello, 2023). Additionally, new analyses from Maszycka Cave in Poland have described cut and broken human bones in patterns consistent with human consumption, reinforcing this cannibalism hypothesis (Marginedas &amp; Saladi\u00e9, 2025). Together, these studies suggest that for some Magdalenian groups, mortuary cannibalism was a habitual way of disposing of the dead, not just a one-off crisis response. At the same time, researchers emphasize that not every modified skeleton indicates blatant consumption of the dead and that ritual or symbolic perspectives must also be considered. Previously noted in chapter 12, Ullrich\u2019s survey of European mortuary practices presents frequent manipulations of corpses from the Palaeolithic through the Hallstatt period. Said manipulations include cut marks, dismemberment, skull fracturing, and marrow extraction (Ullrich, 2005, p. 258), which Ullrich interprets as cannibalistic rites embedded in cult ceremonies rather than everyday subsistence. In the author\u2019s view, some Palaeolithic groups may have believed that consuming members of their community allowed them to take on the strengths,<\/p>\n<figure id=\"attachment_819-3\" aria-describedby=\"caption-attachment-819-3\" style=\"width: 265px\" class=\"wp-caption alignright\"><img class=\"wp-image-819\" src=\"http:\/\/opentextbooks.concordia.ca\/explorationsversiontwo\/wp-content\/uploads\/sites\/71\/2023\/06\/a_-_briana_pobiner_-_figure_1.jpg\" alt=\"\" width=\"265\" height=\"379\" \/><figcaption id=\"caption-attachment-819-3\" class=\"wp-caption-text\">Figure 13.19: View of the hominin tibia and magnified area that shows cut marks. Scale = 4 cm. Credit: 23-199A Figure 1 by Jennifer Clark, Smithsonian Institution, from \"<a href=\"https:\/\/www.si.edu\/newsdesk\/releases\/humans-evolutionary-relatives-butchered-one-another-145-million-years-ago\" target=\"_blank\">Humans\u2019 Evolutionary Relatives Butchered One Another 1.45 Million Years Ago<\/a>,\" \u00a9Smithsonian Institution, used with permission.<\/figcaption><\/figure>\n<p>abilities, or even mental aspects of their dead member; the act of cannibalism may have functioned as a form of appropriating physical and mental powers rather than simply obtaining calories. With that, Neolithic assemblages show how careful taphonomic work can distinguish cuts linked to interpersonal violence from those associated with systemic butchery (Marginedas &amp; Saladi\u00e9, 2025). The findings seek to highlight that some <em>Homo sapiens<\/em> populations combined ritual, mortuary, and nutritional motives when processing human remains.<\/p>\n<p>These past and contemporary findings are significant for future anthropology students as they shed light on biological anthropology methodology and interpretation. Archaeologists are able to distinguish between occasions when humans were handled like any other carcass and times when they were handled in more symbolic ways thanks to factors like cut mark orientation, the timing of bone breakage, and direct comparison with animal remains. Readers interested in exploring this topic further should investigate the context-specific motivations for cannibalism, like nutritional stress, warfare, funerary sites, or ritual power appropriation.<\/p>\n<p>Similar archeological techniques have been used to explore behaviours of cannibalism among Indigenous Huron-Wendat populations in 1651 Canada, where human bones exhibit cutmarks, perimortem fractures, and thermal modifications (Spence &amp; Jackson, 2014). These shared taphonomic signatures across continents reveal recurring practices under ecological stress, bridging prehistoric Europe to North American contexts. Engaging with such analytical techniques opens up new ways that archeologists and anthropologists can investigate the variability in human behaviour, from nutritional crises to mortuary rituals.<\/p>\n<\/div>\n<h3 class=\"import-Normal\"><strong>Peopling of the Americas<\/strong><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">By 25,000 years ago, our species was the only member of <em>Homo<\/em> left on Earth. Gone were the Neanderthals, Denisovans, <em>Homo naledi,<\/em> and <em>Homo floresiensis<\/em>. The range of modern <em>Homo sapiens<\/em> kept expanding eastward into\u2014using the name given to this area by Europeans much later\u2014the Western Hemisphere. This section will address what we know about the peopling of the Americas, from the first entry to these continents to the rapid spread of Indigenous Americans across its varied environments.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">While evidence points to an ancient land bridge called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1778\"><strong>Beringia<\/strong><\/a> that allowed people to cross from what is now northeastern Siberia into modern-day Alaska, what people did to cross this land bridge is still being investigated. For most of the 20th century, the accepted theory was the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1779\"><strong>Ice-Free Corridor model<\/strong><\/a>. It stated that northeast Asians (East Asians and Siberians) first expanded across Beringia inland through a passage between glaciers that opened into the western Great Plains of the United States, just east of the Rocky Mountains, around 13,000 years ago (Swisher Et al. 2013). While life up north in the cold environment would have been harsh, migrating birds and an emerging forest might have provided sustenance as generations expanded through this land (Potter Et al. 2018).<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">However, in recent decades, researchers have accumulated evidence against the Ice-Free Corridor model. Archaeologist K. R. Fladmark (1979) brought the alternate <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1780\"><strong>Coastal Route model<\/strong><\/a> into the archaeological spotlight; researcher Jon M. Erlandson has been at the forefront of compiling support for this theory (Erlandson Et al. 2015). The new focus is the southern edge of the land bridge instead of its centre: About 16,000 years ago, members of our species expanded along the coastline from northeast Asia, east through Beringia, and south down the Pacific Coast of North America while the inland was still sealed off by ice. The coast would have been free of ice at least part of the year, and many resources would have been found there, such as fish (e.g., salmon), mammals (e.g., whales, seals, and otters), and plants (e.g., seaweed).<\/p>\n<h4 class=\"import-Normal\"><em>South through the Americas<\/em><\/h4>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">When the first modern <em>Homo sapiens<\/em> reached the Western Hemisphere, the spread through the Americas was rapid. Multiple migration waves crossed from North to South America (Posth Et al. 2018). Our species took advantage of the lack of hominin competition and the bountiful resources both along the coasts and inland. The Americas had their own wide array of megafauna, which included woolly mammoths (Figure 13.20), mastodons, camels, horses, ground sloths, giant tortoises, and\u2014a favourite of researchers\u2014a two-metre-tall beaver. The reason we cannot see these amazing animals today may be that resources gained from these fauna were crucial to the survival for people over 12,000 years ago (Araujo Et al. 2017). Several sites are notable for what they add to our understanding of the distant past in the Americas, including interactions with megafauna and other elements of the environment.<\/p>\n<figure style=\"width: 242px\" class=\"wp-caption alignleft\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image3-2-1.jpg\" alt=\"A mammoth model with long curving tusks.\" width=\"242\" height=\"323\" \/><figcaption class=\"wp-caption-text\">Figure 13.20: Life-size reconstruction of a woolly mammoth at the Page Museum, part of the La Brea Tar Pits complex in Los Angeles, California. Outside of Africa, megafauna such as this went extinct around the time that humans entered their range. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-14\/\" target=\"_blank\">Woolly Mammoth<\/a> (at <a href=\"https:\/\/tarpits.org\/\" target=\"_blank\">La Brea Tar Pits &amp; Museum<\/a>) by Keith Chan is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">A 2019 discovery may allow researchers to improve theories about the peopling of the Americas. In White Sands National Park, New Mexico, 60 human footprints have been astonishingly dated to around 22,000 years ago (Bennett Et al. 2021). This date and location do not match either the Ice-Free Corridor or Coastal Route models. Researchers are now working to verify the find and adjust previous models to account for the new evidence. This groundbreaking find is sparking new theories; it is another example of the fast pace of research performed on our past.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Monte Verde is a landmark site that shows that the human population had expanded down the whole vertical stretch of the Americas to Chile by 14,600 years ago. The site has been excavated by archaeologist Tom D. Dillehay and his team (2015). The remains of nine distinct edible species of seaweed at the site shows familiarity with coastal resources and relates to the Coastal Route model by showing a connection between the inland people and the sea.<\/p>\n<figure style=\"width: 254px\" class=\"wp-caption alignright\"><img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image21-4.png\" alt=\"A long stone point with small chips around the edge.\" width=\"254\" height=\"362\" \/><figcaption class=\"wp-caption-text\">Figure 13.21: The Clovis point has a distinctive structure. It has a wide tip, and its base has two small projections. This example was carved from chert and found in north-central Ohio, dated to around 11,000 years ago. Credit: <a href=\"https:\/\/www.si.edu\/object\/chndm_15.2012.25\" target=\"_blank\">Clovis Point<\/a> (15.2012.25) by <a href=\"https:\/\/www.si.edu\/\" target=\"_blank\">the Smithsonian<\/a> [Department of Anthropology; Cooper Hewitt, Smithsonian Design Museum] <a href=\"https:\/\/www.si.edu\/termsofuse\" target=\"_blank\">is used for educational and non-commercial purposes as outlined by the Smithsonian.<\/a><\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Named after the town in New Mexico, the Clovis stone-tool style is the first example of a widespread culture across much of North America, between 13,400 and 12,700 years ago (Miller, Holliday, and Bright 2013). Clovis points were fluted with two small projections, one on each end of the base, facing away from the head (Figure 13.21). The stone points found at this site match those found as far as the Canadian border and northern Mexico, and from the west coast to the east coast of the United States. Fourteen Clovis sites also contained the remains of mammoths or mastodons, suggesting that hunting megafauna with these points was an important part of life for the Clovis people. After the spread of the Clovis style, it diversified into several regional styles, keeping some of the Clovis form but also developing their own unique touches.<\/p>\n<h3 class=\"import-Normal\"><strong>The Big Picture: The Assimilation Hypothesis<\/strong><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">How do researchers make sense of all of these modern <em>Homo sapiens<\/em> discoveries that cover over 300,000 years of time and stretch across every continent except Antarctica? How was modern <em>Homo sapiens<\/em> related to archaic <em>Homo sapiens<\/em>?<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1782\">Assimilation hypothesis<\/a><\/strong> proposes that modern <em>Homo sapiens<\/em> evolved in Africa first and expanded out but also interbred with the archaic <em>Homo sapiens<\/em> they encountered outside Africa (Figure 13.22). This hypothesis is powerful since it explains why Africa has the oldest modern human fossils, why early modern humans found in Europe and Asia bear a resemblance to the regional archaics, and why traces of archaic DNA can be found in our genomes today (Dannemann and Racimo 2018; Reich Et al. 2010; Reich Et al. 2011; Slatkin and Racimo 2016; Smith Et al. 2017; Wall and Yoshihara Caldeira Brandt 2016).<\/p>\n<figure style=\"width: 443px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image28-2.png\" alt=\"African Homo erectus expands and gives rise to archaics and modern Homo sapiens groups.\" width=\"443\" height=\"471\" \/><figcaption class=\"wp-caption-text\">Figure 13.22: This diagram shows archaic humans, having evolved from Homo erectus, expanded from Africa and established the Neanderthal and Denisovan groups. In Africa, archaic humans evolved modern traits and expanded from the continent as well, interbreeding with two archaic groups across Europe and Asia. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-14\/\" target=\"_blank\">Assimilation Model (Figure 12.23)l<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Keith Chan and Katie Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">While researchers have produced a model that satisfies the data, there are still a lot of questions for paleoanthropologists to answer regarding our origins. What were the patterns of migration in each part of the world? Why did the archaic humans go extinct? In what ways did archaic and modern humans interact? The definitive explanation of how our species started and what our ancestors did is still out there to be found. You are now in a great place to welcome the next discovery about our distant past\u2014maybe you\u2019ll even contribute to our understanding as well.<\/p>\n<h2 class=\"import-Normal\">The Chain Reaction of Agriculture<\/h2>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">While it may be hard to imagine today, for most of our species\u2019 existence we were nomadic: moving through the landscape without a singular home. Instead of a refrigerator or pantry stocked with food, we procured nutrition and other resources as needed based on what was available in the environment. This section gives an overview of how the foraging lifestyle enabled the expansion of our species and how the invention of a new way of life caused a chain reaction of cultural change.<\/p>\n<h3 class=\"import-Normal\"><strong>The Foraging Tradition<\/strong><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">There are a variety of possible <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1783\">subsistence strategies<\/a><\/strong>, or methods of finding sustenance and resources. To understand our species is to understand the subsistence strategy of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1114\">foraging<\/a><\/strong>, or the search for resources in the environment. While most (but not all) humans today live in cultures that practice <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1784\">agriculture<\/a> <\/strong>(whereby we greatly shape the environment to mass produce what we need), we have spent far more time as nomadic foragers than as settled agriculturalists. As such, it has been suggested that our traits have evolved to be primarily geared toward foraging. For instance, our efficient bipedalism allows persistence-hunting across long distances as well as movement from resource to resource.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">How does human foraging, also known as hunting and gathering, work? Anthropologists have used all four fields to answer this question (see Ember n.d.). Typically, people formed <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1785\"><strong>bands<\/strong><\/a>, or kin-based groups of around 50 people or less (rarely over 100). A band\u2019s organization would be <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1786\"><strong>e<\/strong><strong>galitarian<\/strong><\/a>, with a flexible hierarchy based on an individual\u2019s age, level of experience, and relationship with others. Everyone would have a general knowledge of the skills assigned to their gender roles, rather than specializing in different occupations. A band would be able to move from place to place in the environment, using knowledge of the area to forage (Figure 13.23). In varied environments\u2014from savannas to tropical forests, deserts, coasts, and the Arctic circle\u2014people found sustenance needed for survival.<\/p>\n<p>&nbsp;<\/p>\n<figure style=\"width: 565px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image22.jpg\" alt=\"A hunter holding a bow is crouched among dry grass.\" width=\"565\" height=\"377\" \/><figcaption class=\"wp-caption-text\">Figure 13.23: A present-day San man in Namibia demonstrates hunting using archery. Anthropologists study the San today to learn about the persistence of foraging as a viable lifestyle, while noting how these cultures have changed over time and how they interact with other groups. Credit: <a href=\"https:\/\/www.flickr.com\/photos\/charlesfred\/2129551464\" target=\"_blank\">San hunter w\u0131th bow and arrow<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/charlesfred\/\" target=\"_blank\">CharlesFred<\/a> has been modified (colour modified) and is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\" target=\"_blank\">CC BY-NC-SA 2.0 License.<\/a><\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Humans made extensive use of the foraging subsistence strategy, but this lifestyle did have limitations. The ease of foraging depended on the richness of the environment. Due to the lack of storage, resources had to be dependably found when needed. While a bountiful environment would require just a few hours of foraging a day and could lead to a focus on one location, the level and duration of labour increased greatly in poor or unreliable environments. Labour was also needed to process the acquired resources, which contributed to the foragers\u2019 daily schedule (Crittenden and Schnorr 2017).<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The adaptations to foraging found in modern <em>Homo sapiens<\/em> may explain why our species became so successful both within Africa and in the rapid expansion around the world. Overcoming the limitations, each generation at the edge of our species\u2019s range would have found it beneficial to expand a little further, keeping contact with other bands but moving into unexplored territory where resources were more plentiful. The cumulative effect would have been the spread of modern <em>Homo sapiens<\/em> across continents and hemispheres.<\/p>\n<h2 class=\"import-Normal\"><strong>Why Agriculture?<\/strong><\/h2>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">After hundreds of thousands of years of foraging, some groups of people around 12,000 years ago started to practice agriculture. This transition, called the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1787\"><strong>Neolithic Revolution<\/strong>,<\/a> occurred at the start of the <strong>Holocene<\/strong> epoch. While the reasons for this global change are still being investigated, two likely co-occurring causes are a growing human population and natural global climate change.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Overcrowding could have affected the success of foraging in the environment, leading to the development of a more productive subsistence strategy (Cohen 1977). Foraging works best with low population densities since each band needs a lot of space to support itself. If too many people occupy the same environment, they deplete the area faster. The high population could exceed the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1788\">carrying capacity<\/a><\/strong>, or number of people a location can reliably support. Reaching carrying capacity on a global level due to growing population and limited areas of expansion would have been an increasingly pressing issue after the expansion through the major continents by 14,600 years ago.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">A changing global climate immediately preceded the transition to agriculture, so researchers have also explored a connection between the two events. Since the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1789\">Last Glacial Maximum<\/a><\/strong> of 23,000 years ago, the Earth slowly warmed. Then, from 13,000 to 11,700 years ago, the temperature in most of the Northern Hemisphere dropped suddenly in a phenomenon called the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1790\"><strong>Younger Dryas<\/strong>.<\/a> Glaciers returned in Europe, Asia, and North America. In Mesopotamia, which includes the Levant, the climate changed from warm and humid to cool and dry. The change would have occurred over decades, disrupting the usual nomadic patterns and subsistence of foragers around the world. The disruption to foragers due to the temperature shift could have been a factor in spurring a transition to agriculture. Researchers Gregory K. Dow and colleagues (2009) believe that foraging bands would have clustered in the new resource-rich places where people started to direct their labour to farming the limited area. After the Younger Dryas ended, people expanded out of the clusters with their agricultural knowledge (Figure 13.24).<\/p>\n<figure style=\"width: 570px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image7-6.png\" alt=\"Map shows that agriculture was invented in at least six parts of the world.\" width=\"570\" height=\"267\" \/><figcaption class=\"wp-caption-text\">Figure 13.24: The map shows the areas where agriculture was independently invented around the world and where they spread. Blue arrows show the spread of agriculture from these zones to other regions. <a href=\"https:\/\/docs.google.com\/document\/d\/1VUDKMBJYS_jNONjLxT04jQN0_z9Ua50BRN6auGSHUuU\/edit\" target=\"_blank\">A full text description of this image is available<\/a>. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Centres_of_origin_and_spread_of_agriculture.svg\" target=\"_blank\">Centres of origin and spread of agriculture<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Joe_Roe\" target=\"_blank\">Joe Roe<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The double threat of the limitation of human continental expansion and the sudden global climate change may have placed bands in peril as more populations outpaced their environment\u2019s carrying capacity. Not only had a growing population may have led to increased competition with other bands, but environments worldwide had shifted to create more uncertainty. As such, it has been proposed that as people in different areas around the world faced this unpredictable situation, they became the independent inventors of agriculture.<\/p>\n<h2 class=\"import-Normal\"><strong>Agriculture around the World<\/strong><\/h2>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Due to global changes to the human experience starting from 12,000 years ago, it has been suggested that cultures with no knowledge of each other turned toward intensely farming their local resources (see Figure 13.24).\u00a0 It is proposed that the first farmers engaged in artificial selection of their domesticates to enhance useful traits over generations. The switch to agriculture took time and effort with no guarantee of success and constant challenges (e.g. fires, droughts, diseases, and pests). The regions with the most widespread impact in the face of these obstacles became the primary centres of agriculture (Figure 13.25; Fuller 2010):<\/p>\n<ul>\n<li class=\"import-Normal\" style=\"text-indent: 0pt\">Mesopotamia: The Fertile Crescent from the Tigris and Euphrates rivers through the Levant was where bands started to domesticate plants and animals around 12,000 years ago. The connection between the development of agriculture and the Younger Dryas was especially strong here. Farmed crops included wheat, barley, peas, and lentils. This was also where cattle, pigs, sheep, and goats were domesticated.<\/li>\n<li class=\"import-Normal\" style=\"text-indent: 0pt\">South and East Asia: Multiple regions across this land had varieties of rice, millet, and soybeans by 10,000 years ago. Pigs were farmed with no connection to Mesopotamia. Chickens were also originally from this region, bred for fighting first and food second.<\/li>\n<li class=\"import-Normal\" style=\"text-indent: 0pt\">New Guinea: Agriculture started here 10,000 years ago. Bananas, sugarcane, and taro were native to this island. Sweet potatoes were brought back from voyages to South America around the year C.E. 1000. No known animal farming occurred here.<\/li>\n<li class=\"import-Normal\" style=\"text-indent: 0pt\">Mesoamerica: Agriculture from Central Mexico to northern South America also occurred from 10,000 years ago; it was also only plant based. Maize was a crop bred from teosinte grass, which has become one of the global staples. Beans, squash, and avocados were also grown in this region.<\/li>\n<li class=\"import-Normal\" style=\"text-indent: 0pt\">The Andes: Starting around 8,000 years ago, local domesticated plants started with squash but later included potatoes, tomatoes, beans, and quinoa. Maize was brought down from Mesoamerica. The main farm animals were llamas, alpacas, and guinea pigs.<\/li>\n<li class=\"import-Normal\" style=\"text-indent: 0pt\">Sub-Saharan Africa: This region went through a change 5,000 years ago called the Bantu expansion. The Bantu agriculturalists were established in West Central Africa and then expanded south and east. Native varieties of rice, yams, millet, and sorghum were grown across this area. Cattle were also domesticated here.<\/li>\n<li class=\"import-Normal\" style=\"text-indent: 0pt\">Eastern North America: This region was the last major independent agriculture centre, from 4,000 years ago. Squash and sunflower are the produce from this region that are most known today, though sumpweed and pitseed goosefoot were also farmed. Hunting was still the main source of animal products.<\/li>\n<\/ul>\n<figure style=\"width: 482px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image23-1-1.jpg\" alt=\"Farmers plow a flooded field. Each plow is pulled by two oxen. \" width=\"482\" height=\"320\" \/><figcaption class=\"wp-caption-text\">Figure 13.25: Rice farmers in the present day using draft cattle to prepare their field. Credit: <a href=\"https:\/\/www.flickr.com\/photos\/ricephotos\/7554483250\" target=\"_blank\">Plowing muddy field using cattle<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/ricephotos\/\" target=\"_blank\">IRRI Photos<\/a> (International Rice Research Institute) has been modified (colour modified) and is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\" target=\"_blank\">CC BY-NC-SA 2.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">By 5,000 years ago, our species was well within the Neolithic Revolution. Agriculturalists spread to neighbouring parts of the world with their domesticates, further expanding the use of this subsistence strategy. From this point, the human species changed from being primarily foragers to primarily agriculturalists with skilled control of their environments. The planet changed from mostly unaffected by human presence to being greatly transformed by humans. The revolution took millennia, but it was a true revolution as our species\u2019 lifestyle was dramatically reshaped.<\/p>\n<h3 class=\"import-Normal\"><strong>Cultural Effects of Agriculture<\/strong><\/h3>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The worldwide adoption of agriculture altered the course of human culture and history forever. The core change in human culture due to agriculture is the move toward not moving: rather than live a nomadic lifestyle, farmers had to remain in one area to tend to their crops and livestock. The term for living bound to a certain location is <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1793\">sedentarism<\/a><\/strong>. This led to new aspects of life that were uncommon among foragers: the construction of permanent shelters and agricultural infrastructure, such as fields and irrigation, plus the development of storage technology, such as pottery, to preserve extra resources in case of future instability.<\/p>\n<figure style=\"width: 359px\" class=\"wp-caption alignright\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image20-1-1.jpg\" alt=\"Multistory buildings surrounding a greek-style plaza.\" width=\"359\" height=\"270\" \/><figcaption class=\"wp-caption-text\">Figure 13.26: View of downtown San Diego taken by the author at a shopping complex during a break from jury duty. Here, people live amongst structures that facilitate commerce, government, tourism, and art. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-14\/\" target=\"_blank\">Downtown San Diego (October 13, 2016; Figure 12.28)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Keith Chan is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\"> CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The high productivity of successful agriculture sparked further changes (Smith 2009). It is argued that since successful agriculture produced a much greater amount of food and other resources per unit of land compared to foraging, the population growth rate skyrocketed. The surplus of a bountiful harvest also provided insurance for harder times, reducing the risk of famine and bringing change to society as well. With a few farming households producing enough food to feed many others, people could start specializing in roles such as craftspeople, traders, religious figures, and artists, spurring innovation in these areas as people could now devote time and effort toward specific skills. These interdependent people would settle an area together for convenience, and over time, the growth of these settlements led to <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1794\">urbanization<\/a><\/strong>, the founding of cities that became the foci of human interaction (Figure 13.26).<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The formation of cities led to new issues that sparked the growth of further specializations, called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1795\">institutions<\/a><\/strong>. These are cultural constructs that exist beyond the individual and have wide control over a population. Leadership of these cities became hierarchical with different levels of rank and control. The stratification of society increased social inequality between those with more or less power over others. Under leadership, people built impressive <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1796\">monumental architecture<\/a><\/strong>, such as pyramids and palaces, that embodied the wealth and power of these early cities. Alliances could unite cities, forming the earliest states. In several regions of the world, state organization expanded into empires, wide-ranging political entities that covered a variety of cultures.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Urbanization brought new challenges as well. The concentration of sedentary peoples was ideal for infectious diseases to thrive since they could jump from person to person and even from livestock to person (Armelagos, Brown, and Turner 2005). While successful agriculture provided a large surplus of food to thwart famine, the food produced offered less diverse food sources than foragers\u2019 diets (Cohen and Armelagos 1984; Cohen and Crane-Kramer 2007). This shift in nutrition caused other diseases to flourish among those who adopted farming, such as dental cavities and malocclusion (the misalignment of teeth caused by soft, agricultural diets). The need to extract \u201cwisdom teeth\u201d or third molars seen in agricultural cultures today stems from this misalignment between the environment our ancestors adapted to and our lifestyles today.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">As the new disease trends show, the adoption of agriculture and the ensuing cultural changes were not entirely positive. It is also important to note that this is not an absolutely linear progression of human culture from simple to complex. In many cases, empires have collapsed and, in some cases, cities dispersed to low-density bands that rejected institutions. However, a global trend has emerged since the adoption of agriculture, wherein population and social inequality have increased, leading to the massive and influential nation-states of today.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">The rise of states in Europe has a direct impact on many of this book\u2019s topics. Science started as a European cultural practice by the upper class that became a standardized way to study the world. Education became an institution to provide a standardized path toward producing and gaining knowledge. The scientific study of human diversity, embroiled in the race concept that still haunts us today, was connected to the European slave trade and colonialism.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Also starting in Europe, the Industrial Revolution of the 19th century turned cities into centres of mass manufacturing and spurred the rapid development of inventions (Figure 13.27). In the technologically interconnected world of today, human society has reached a new level of complexity with <strong>globalization<\/strong>. In this system, goods are mass-produced and consumed in different parts of the world, weakening the reliance on local farms and factories. The imbalanced relationship between consumers and producers of goods further increases economic inequality.<\/p>\n<p>&nbsp;<\/p>\n<figure style=\"width: 465px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image1-3.jpg\" alt=\"A yellow farm vehicle driving into crops in a field.\" width=\"465\" height=\"310\" \/><figcaption class=\"wp-caption-text\">Figure 13.27: This combine harvester can collect and process grain at a massive scale. Our food now commonly comes from enormous farms located around the world. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Combine_CR9060.jpeg\" target=\"_blank\">Combine CR9060<\/a> by Hertzsprung is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\" target=\"_blank\">CC BY-SA 3.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">As states based on agriculture and industry keep exerting influence on humanity today, there are people, like the Hadzabe of Tanzania, who continue to live a lifestyle centred on foraging. Due to the overwhelming force that agricultural societies exert, foragers today have been marginalized to live in the least habitable parts of the world\u2014the areas that are not conducive to farming, such as tropical rainforests, deserts, and the Arctic (Headland Et al. 1989). Foragers can no longer live in the abundant environments that humans would have enjoyed before the Neolithic Revolution. Interactions with agriculturalists are typically imbalanced, with trade and other exchanges heavily favouring the larger group. One of anthropology\u2019s important roles today is to intelligently and humanely manage equitable interactions between people of different backgrounds and levels of influence.<\/p>\n<div class=\"textbox\">\n<h2 class=\"import-Normal\">Special Topic: Indigenous Land Management<\/h2>\n<p class=\"import-Normal\">Insight into the lives of past modern humans has evolved as researchers revise previous theories and establish new connections with Indigenous knowledge holders.<\/p>\n<p class=\"import-Normal\">The outdated view of foraging held that people lived off of the land without leaving an impact on the environment. Accompanying this idea was anthropologist Marshall Sahlins\u2019s (1968) proposal that foragers were the \u201coriginal affluent society\u201d since they were meeting basic needs and achieving satisfaction with less work hours than agriculturalists and city-dwellers. This view countered an earlier idea that foragers were always on the brink of starvation. Sahlins\u2019s theory took hold in the public eye as an attractive counterpoint to our busy contemporary lives in which we strive to meet our endless wants.<\/p>\n<p class=\"import-Normal\">A fruitful type of study involving researchers collaborating with Indigenous experts has found that foragers did not just live off the land with minimal effort nor were they barely surviving in unchanging environments. Instead, they shaped the landscape to their needs using labour and strategies that were more subtle than what European colonizers and subsequent researchers were used to seeing. Research from two regions shows the latest developments in understanding Indigenous land management.<\/p>\n<p class=\"import-Normal\">In British Columbia, Canada, the bridging of scientific and Indigenous perspectives has shown that the forests of the region are not untouched wilderness but, rather, have been crafted by Indigenous peoples thousands of years ago. Forest gardens adjacent to archaeological sites show higher plant diversity than unmanaged places even after 150 years (Armstrong Et al. 2021). On the coast, 3,500-year-old archaeological sites are evidence of constructed clam gardens, according to Indigenous experts (Lepofsky Et al. 2015). Another project, in consultation with Elders of the T\u2019exelc (William Lakes First Nation) in British Columbia, introduced researchers to explanations of how forests were managed before the practice was disrupted by European colonialism (Copes-Gerbitz Et al. 2021). Careful management of controlled fires reduced the density of the forest to favour plants such as raspberries and allow easier movement through the landscape.<\/p>\n<p class=\"import-Normal\">Similarly, the study of landscapes in Australia, in consultation with Aboriginal Australians today, shows that areas previously considered wilderness by scientists were actually the result of controlling fauna and fires. The presence of grasslands with adjacent forests were purposely constructed to attract kangaroos for hunting (Gammage 2008). People also managed other animal and insect life, from emus to caterpillars. In Tasmania, a shift from productive grassland to wildfire-prone rainforest occurred after Aboriginal Australian land management was replaced by British colonial rule (Fletcher, Hall, and Alexander 2021). The site of Budj Bim of the Gunditjmara people has archaeological features of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1695_1798\">aquaculture<\/a><\/strong>, or the farming of fish, that date back 6,600 years (McNiven Et al. 2012; McNiven Et al. 2015). These examples show that Indigenous knowledge of how to manipulate the environment may be invaluable at the state level, such as by creating an Aboriginal ranger program to guide modern land management.<\/p>\n<\/div>\n<h2 class=\"import-Normal\">The Future of Humanity<\/h2>\n<p class=\"import-Normal\">A common question stemming from understanding human evolution is: What will the genetic and biological traits of our species be hundreds of thousands of years in the future? When faced with this question, people tend to think of directional selection. Maybe our braincases will be even larger, resembling the large-headed and small-bodied aliens of science fiction (Figure 13.28). Or, our hands could be specialized for interacting with our touch-based technology with less risk of repetitive injury. These ideas do not stand up to scrutiny. Since natural selection is based on adaptations that increase reproductive success, any directional change must be due to a higher rate of producing successful offspring compared to other alleles. Larger brains and more agile fingers would be convenient to possess, but they do not translate into an increase in the underlying allele frequencies.<\/p>\n<figure style=\"width: 571px\" class=\"wp-caption aligncenter\"><img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image8-4.png\" alt=\"One human has typical features; the other has a tall braincase.\" width=\"571\" height=\"279\" \/><figcaption class=\"wp-caption-text\">Figure 13.28: Will we evolve toward even more globular brains? Actually, this trend is not likely to continue for our species. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-14\/\" target=\"_blank\">Hypothetical image of future human evolution (Figure 12.30)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\" target=\"_blank\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Mary Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\" target=\"_blank\">CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Scientists are hesitant to professionally speculate on the unknowable, and we will never know what is in store for our species one thousand or one million years from now, but there are two trends in human evolution that may carry on into the future: increased genetic variation and a reduction in regional differences.<\/p>\n<p class=\"import-Normal\">Rather than a directional change, genetic variation in our species could expand. Our technology can protect us from extreme environments and pathogens, even if our biological traits are not tuned to handle these stressors. The rapid pace of technological advancement means that biological adaptations will become less and less relevant to reproductive success, so nonbeneficial genetic traits will be more likely to remain in the gene pool. Biological anthropologist Jay T. Stock (2008) views environmental stress as needing to defeat two layers of protection before affecting our genetics. The first layer is our cultural adaptations. Our technology and knowledge can reduce pressure on one\u2019s genotype to be \u201cjust right\u201d to pass to the next generation. The second defence is our flexible physiology, such as our acclimatory responses. Only stressors not handled by these powerful responses would then cause natural selection on our alleles. These shields are already substantial, and cultural adaptations will only keep increasing in strength.<\/p>\n<p class=\"import-Normal\">The increasing ability to travel far from one\u2019s home region means that there will be a mixing of genetic variation on a global level in the future of our species. In recent centuries, gene flow of people around the world has increased, creating admixture in populations that had been separated for tens of thousands of years. For skin colour, this means that populations all around the world could exhibit the whole range of skin colours, rather than the current pattern of decreasing melanin pigment farther from the equator. The same trend of intermixing would apply to all other traits, such as blood types. While our genetics will become more varied, the variation will be more intermixed instead of regionally isolated.<\/p>\n<p class=\"import-Normal\">Our distant descendants will not likely be dextrous ultraintellectuals; more likely, they will be a highly variable and mobile species supported by novel cultural adaptations that make up for any inherited biological limitations. Technology may even enable the editing of DNA directly, changing these trends. With the uncertainty of our future, these are just the best-educated guesses for now. Our future is open and will be shaped little by little by the environment, our actions, and the actions of our descendants.<\/p>\n<h2>Cultural Connections and Contemporary Implications<\/h2>\n<p>The expansion of <em>Homo sapiens<\/em> across the globe and the subsequent and increasingly complex societies they developed have fundamentally altered the relationship between humans and the natural world. Throughout this chapter, we have seen how cultural innovations\u2014agriculture, urbanization, and technological development\u2014enabled humans to modify the environment in ways that no previous hominin could. At this point, the cumulative changes by <em>Homo sapiens<\/em> have irreversibly changed the planet, and some anthropologists and Earth scientists argue that we have entered a new stage of Earth\u2019s history known as the <em>Anthropocene<\/em> (notably the Nobel Laureate Paul J. Crutzen, known as one of the forces in popularizing the term and his part in the <em>Montreal Protocol; <\/em>cf<em>. <\/em>United Nations, 1987; Steffen, 2021<\/p>\n<p>The Anthropocene (or <em>Human Epoch<\/em>) describes a period in which natural processes and human activities have become inseparable, such that the future of Earth's ecosystems and humanity are increasingly dependent on one another (Steffen, 2021). This proposed epoch emphasizes humans\u2019 role as a planetary force capable of reshaping Earth on multiple levels; landscapes are transformed by mining, dam construction, urban expansion, and resource extraction. With this, we are witnessing increasing extinction, the introduction of invasive species, and genetic modification of organisms and unlike earlier periods of human evolution, these changes are occurring simultaneously across the entire planet, affecting ecological systems on a global scale. Although the Anthropocene has been proposed as a new geological epoch beginning in the mid-twentieth century, it has been refused formal adoption within the Geological Time Scale It is generally considered as a part of the Holocene, where agriculture and pastoralism significantly changed the earth despite an argument from a working group in the IPCC (Waters, C 2016).<\/p>\n<p>Nevertheless, the concept of the Anthropocene places modern human societies in positions of unprecedented responsibility. Climate change is not experienced equally, with poverty and social inequality increasing the vulnerability to these challenges, framing the Anthropocene as an environmental concept and a biocultural one as well. Just as agriculture transformed human societies, the choices made by modern populations regarding energy use, technology, and resource management will shape the environments inhabited by future generations and the continued evolution of our species. The Anthropocene therefore reminds us that anthropology and other disciplines aide us in understanding the evolutionary past they are also essential for understanding humanity's role in shaping the future.<\/p>\n<h4>Discussion questions<\/h4>\n<ul>\n<li>How do you see humans shaping the Earth today? Which of these changes do you consider permanent, temporary, harmful, or beneficial?<\/li>\n<li>How might the Anthropocene affect humans as a species? Like other species affected by environmental change, do you think humans could face extinction, or will our ability to modify our environment allow us to adapt?<\/li>\n<li>If humans eventually become a multiplanetary species, would the Anthropocene simply continue beyond Earth? What might this mean for our relationship with the environments we inhabit?<\/li>\n<\/ul>\n<div class=\"textbox\">\n<h2 class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">Hominin Species Summary<\/span><\/h2>\n<div style=\"text-align: left\">\n<table class=\"aligncenter\" style=\"width: 450pt\">\n<tbody>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Hominin<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">Modern<em> Homo sapiens<\/em><\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Dates<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">315,000 years ago to present<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Region(s)<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Starting in Africa, then expanding around the world<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Famous discoveries<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff;margin-left: 1.5pt;text-indent: 0pt\"><span style=\"color: #000000\">Cro-Magnon individuals, discovered 1868 in Dordogne, France. Otzi the Ice Man, discovered 1991 in the Alps between Austria and Italy. Kennewick man, discovered 1996 in Washington state.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Brain size<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">1400 cc average<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Dentition<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">Extremely small with short cusps.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Cranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">An extremely globular brain case and gracile features throughout the cranium. The mandibular symphysis forms a chin at the anterior-most point.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Postcranial features<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Gracile skeleton adapted for efficient bipedal locomotion at the expense of the muscular strength of most other large primates.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Culture<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">Extremely extensive and varied culture with many spoken and written languages. Art is ubiquitous. Technology is broad in complexity and impact on the environment.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Table1-R\" style=\"height: 0\">\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\"><strong>Other<\/strong><\/span><\/p>\n<\/td>\n<td class=\"Table1-C\" style=\"background-color: transparent;padding: 5pt 5pt 5pt 5pt;border: solid #000000 1pt\">\n<p class=\"import-Normal\"><span style=\"color: #000000\">The only living hominin. Chimpanzees and bonobos are the closest living relatives.<\/span><\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div class=\"textbox shaded\">\n<h2 class=\"import-Normal\">Summary<\/h2>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Modern <em>Homo sapiens<\/em> is the species that took the hominin lifestyle the furthest to become the only living member of that lineage. The largest factor that allowed us to persist while other hominins went extinct was likely our advanced ability to culturally adapt to a wide variety of environments. Our species, with its skeletal and behavioural traits, was well-suited to be generalist-specialists who successfully foraged across most of the world\u2019s environments. The biological basis of this adaptation was our reorganized brain that facilitated innovation in cultural adaptations and intelligence for leveraging our social ties and finding ways to acquire resources from the environment. As the brain\u2019s ability increased, it shaped the skull by reducing the evolutionary pressure to have large teeth and robust cranial bones to produce the modern <em>Homo sapiens<\/em> face.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Our ability to be generalist-specialists is seen in the geographical range that modern <em>Homo sapiens<\/em> covered in 300,000 years. In Africa, our species formed from multiregional gene flow that loosely connected archaic humans across the continent. People then expanded out to the rest of the continental Eurasia and even further to the Americas.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">For most of our species\u2019s existence, foraging was the general subsistence strategy within which people specialized to culturally adapt to their local environment. With omnivorousness and mobility, people found ways to extract and process resources, shaping the environment in return. When resource uncertainty hit the species, people around the world focused on agriculture to have a firmer control of sustenance. The new strategy shifted human history toward exponential growth and innovation, leading to our high dependence on cultural adaptations today.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">While a cohesive image of our species has formed in recent years, there is still much to learn about our past. The work of many driven researchers shows that there are amazing new discoveries made all the time that refine our knowledge of human evolution. Technological innovations such as DNA analysis enable scientists to approach lingering questions from new angles. The answers we get allow us to ask even more insightful questions that will lead us to the next revelation. Like the pink limestone strata at Jebel Irhoud, previous effort has taken us so far and you are now ready to see what the next layer of discovery holds.<\/p>\n<h2 class=\"import-Normal\">Review Questions<strong><br \/>\n<\/strong><\/h2>\n<ul>\n<li>What are the skeletal and behavioural traits that define modern <em>Homo sapiens<\/em>? What are the evolutionary explanations for its presence?<\/li>\n<li>What are some creative ways that researchers have learned about the past by studying fossils and artifacts?<\/li>\n<li>How do the discoveries mentioned in \u201cFirst Africa, Then the World\u201d fit the Assimilation model?<\/li>\n<li>What is foraging? What adaptations do we have for this subsistence strategy? Could you train to be a skilled forager?<\/li>\n<li>What are aspects of your life that come from dependence on agriculture and its cultural effects? Where did the ingredients of your favourite foods originate from?<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<h2 class=\"__UNKNOWN__\">Key Terms<\/h2>\n<div class=\"__UNKNOWN__\">\n<p class=\"import-Normal\"><strong>African multiregionalism<\/strong>: The idea that modern <em>Homo sapiens<\/em> evolved as a complex web of small regional populations with sporadic gene flow among them.<\/p>\n<p class=\"import-Normal\"><strong>Agriculture<\/strong>: The mass production of resources through farming and domestication.<\/p>\n<p class=\"import-Normal\"><strong>Aquaculture<\/strong>: The farming of fish using techniques such as trapping, channels, and artificial ponds.<\/p>\n<p class=\"import-Normal\"><strong>Assimilation <\/strong><strong>hypothesis<\/strong>: Current theory of modern human origins stating that the species evolved first in Africa and interbred with archaic humans of Europe and Asia.<\/p>\n<p class=\"import-Normal\"><strong>Atlatl<\/strong>: A handheld spear thrower that increased the force of thrown projectiles.<\/p>\n<p class=\"import-Normal\"><strong>Band<\/strong>: A small group of people living together as foragers.<\/p>\n<p class=\"import-Normal\"><strong>Beringia<\/strong>: Ancient landmass that connected Siberia and Alaska. The ancestors of Indigenous Americans would have crossed this area to reach the Americas.<\/p>\n<p class=\"import-Normal\"><strong>Carrying capacity<\/strong>: The amount of organisms that an environment can reliably support.<\/p>\n<p class=\"import-Normal\"><strong>Coastal Route model<\/strong>: Theory that the first Paleoindians crossed to the Americas by following the southern coast of Beringia.<\/p>\n<p class=\"import-Normal\"><strong>Early Modern <\/strong><strong><em>Homo sapiens<\/em><\/strong><strong>, Early Anatomically Modern Human<\/strong>: Terms used to refer to transitional fossils between archaic and modern <em>Homo sapiens<\/em> that have a mosaic of traits. Humans like ourselves, who mostly lack archaic traits, are referred to as Late Modern <em>Homo sapiens<\/em> and simply Anatomically Modern Humans.<\/p>\n<p class=\"import-Normal\"><strong>Egalitarian<\/strong>: Human organization without strict ranks. Foraging societies tend to be more egalitarian than those based on other subsistence strategies.<\/p>\n<p class=\"import-Normal\"><strong>Foraging<\/strong>: Lifestyle consisting of frequent movement through the landscape and acquiring resources with minimal storage capacity.<\/p>\n<p class=\"import-Normal\"><strong>Generalist-specialist niche<\/strong>: The ability to survive in a variety of environments by developing local expertise. Evolution toward this niche may have been what allowed modern <em>Homo sapiens<\/em> to expand past the geographical range of other human species.<\/p>\n<p class=\"import-Normal\"><strong>Globalization<\/strong>: A recent increase in the interconnectedness and interdependence of people that is facilitated with long-distance networks.<\/p>\n<p class=\"import-Normal\"><strong>Globular<\/strong>: Having a rounded appearance. Increased globularity of the braincase is a trait of modern <em>Homo sapiens<\/em>.<\/p>\n<p class=\"import-Normal\"><strong>Gracile<\/strong>: Having a smooth and slender quality; the opposite of robust.<\/p>\n<p class=\"import-Normal\"><strong>Holocene<\/strong>: The epoch of the Cenozoic Era starting around 12,000 years ago and lasting arguably through the present.<\/p>\n<p class=\"import-Normal\"><strong>Ice-Free Corridor model<\/strong>: Theory that the first Native Americans crossed to the Americas through a passage between glaciers.<\/p>\n<p class=\"import-Normal\"><strong>Institutions<\/strong>: Long-lasting and influential cultural constructs. Examples include government, organized religion, academia, and the economy.<\/p>\n<p class=\"import-Normal\"><strong>Last Glacial Maximum<\/strong>: The time 23,000 years ago when the most recent ice age was the most intense.<\/p>\n<p class=\"import-Normal\"><strong>Later Stone Age<\/strong>: Time period following the Middle Stone Age with a diversification in tool types, starting around 50,000 years ago.<\/p>\n<p class=\"import-Normal\"><strong>Levant<\/strong>: The eastern coast of the Mediterranean. The site of early modern human expansion from Africa and later one of the centres of agriculture.<\/p>\n<p class=\"import-Normal\"><strong>Megafauna<\/strong>: Large ancient animals that may have been hunted to extinction by people around the world.<\/p>\n<p class=\"import-Normal\"><strong>Mental eminence<\/strong>: The chin on the mandible of modern <em>H. sapiens<\/em>. One of the defining traits of our species.<\/p>\n<p class=\"import-Normal\"><strong>Microlith<\/strong>: Small stone tool found in the Later Stone Age; also called a bladelet.<\/p>\n<p class=\"import-Normal\"><strong>Middle Stone Age<\/strong>: Time period known for Mousterian lithics that connects African archaic to modern <em>Homo sapiens<\/em>.<\/p>\n<p class=\"import-Normal\"><strong>Monumental architecture<\/strong>: Large and labour-intensive constructions that signify the power of the elite in a sedentary society. A common type is the pyramid, a raised crafted structure topped with a point or platform.<\/p>\n<p class=\"import-Normal\"><strong>Mosaic<\/strong>: Composed from a mix or composite of traits.<\/p>\n<p class=\"import-Normal\"><strong>Neolithic Revolution<\/strong>: Time of rapid change to human cultures due to the invention of agriculture, starting around 12,000 years ago.<\/p>\n<p class=\"import-Normal\"><strong>Ochre<\/strong>: Iron-based mineral pigment that can be a variety of yellows, reds, and browns. Used by modern human cultures worldwide since at least 80,000 years ago.<\/p>\n<p class=\"import-Normal\"><strong>Sahul<\/strong>: Ancient landmass connecting New Guinea and Australia.<\/p>\n<p class=\"import-Normal\"><strong>Sedentarism<\/strong>: Lifestyle based on having a stable home area; the opposite of nomadism.<\/p>\n<p class=\"import-Normal\"><strong>Southern Dispersal model<\/strong>: Theory that modern <em>H. sapiens<\/em> expanded from East Africa by crossing the Red Sea and following the coast east across Asia.<\/p>\n<p class=\"import-Normal\"><strong>Subsistence strategy<\/strong>: The method an organism uses to find nourishment and other resources.<\/p>\n<p class=\"import-Normal\"><strong>Sunda<\/strong>: Ancient Asian landmass that incorporated modern Southeast Asia.<\/p>\n<p class=\"import-Normal\"><strong>Supraorbital torus<\/strong>: The bony brow ridge across the top of the eye orbits on many hominin crania.<\/p>\n<p class=\"import-Normal\"><strong>Upper Paleolithic<\/strong>: Time period considered synonymous with the Later Stone Age.<\/p>\n<p class=\"import-Normal\"><strong>Urbanization<\/strong>: The increase of population density as people settled together in cities.<\/p>\n<p class=\"import-Normal\"><strong>Wallacea<\/strong>: Archipelago southeast of Sunda with different biodiversity than Asia.<\/p>\n<p class=\"import-Normal\"><strong>Younger Dryas<\/strong>: The rapid change in global climate\u2014notably a cooling of the Northern Hemisphere\u201413,000 years ago.<\/p>\n<h2 class=\"import-Normal\">For Further Exploration<\/h2>\n<h3 class=\"import-Normal\" style=\"text-indent: 0pt\"><strong>Websites<\/strong><\/h3>\n<p>First-person virtual tour of Lascaux cave with annotated cave art: Minist\u00e8re de la Culture and Mus\u00e9e d\u2019Arch\u00e9ologie Nationale. \u201c<a href=\"https:\/\/archeologie.culture.fr\/lascaux\/en\/visit-cave\" target=\"_blank\" rel=\"noopener\">Visit the cave<\/a>\u201d Lascaux website.<\/p>\n<p>Online anthropology magazine articles related to paleoanthropology and human evolution: SAPIENS. \u201c<a href=\"https:\/\/www.sapies.org\/category\/evolution\/\" target=\"_blank\" rel=\"noopener\">Evolution<\/a>.\u201d <em>SAPIENS<\/em> website.<\/p>\n<p>Various presentations of information about hominin evolution: Smithsonian Institution. \u201c<a href=\"https:\/\/humanorigins.si.edu\" target=\"_blank\" rel=\"noopener\">What does it mean to be human?<\/a>\u201d <em>Smithsonian National Museum of Natural History<\/em> website.<\/p>\n<p>Magazine-style articles on archaeology and paleoanthropology: ThoughtCo. \u201c<a href=\"https:\/\/www.thoughtco.com\/archaeology-4133504\" target=\"_blank\" rel=\"noopener\">Archaeology<\/a>.\u201d ThoughtCo. Website.<\/p>\n<p>Database of comparisons across hominins and primates: University of California, San Diego. \u201c<a href=\"https:\/\/carta.anthropogeny.org\/moca\/domains\" target=\"_blank\" rel=\"noopener\">MOCA Domains<\/a>.\u201d <em>Center for Academic Research &amp; Training in Anthropogeny<\/em> website.<\/p>\n<h3><strong>Books<\/strong><\/h3>\n<p>Engaging book that covers human-made changes to the environment with industrialization and globalization: Kolbert, Elizabeth. 2014. <em>The Sixth Extinction: An Unnatural History<\/em>. New York: Bloomsbury.<\/p>\n<p>Overview of what human life was like among the environmental shifts of the Ice Age: Woodward, Jamie. 2014. <em>The Ice Age: A Very Short Introduction<\/em>. Oxford: OUP Press.<\/p>\n<h3><strong>Articles<\/strong><\/h3>\n<p>Recent review paper about the current state of paleoanthropology research: Stringer, C. 2016. \u201c<a href=\"https:\/\/doi.org\/10.1098\/rstb.2015.0237\" target=\"_blank\" rel=\"noopener\">The Origin and Evolution of <em>Homo sapiens<\/em><\/a>.\u201d <em>Philosophical Transactions of the Royal Society B<\/em> 371 (1698).<\/p>\n<p>Overview of the history of American paleoanthropology and the many debates that have occurred over the years: Trinkaus, E. 2018. \u201cOne Hundred Years of Paleoanthropology: An American Perspective.\u201d <em>American Journal of Physical Anthropology<\/em> 165 (4): 638\u2013651.<\/p>\n<p>Amazing magazine article that synthesizes hominin evolution and why it is important to study this subject: Wheelwright, Jeff. 2015. \u201c<a href=\"https:\/\/discovermagazine.com\/2015\/may\/16-days-of-dysevolution\" target=\"_blank\" rel=\"noopener\">Days of Dysevolution<\/a>.\u201d <em>Discover<\/em> 36 (4): 33\u201339.<\/p>\n<p>Fascinating research on \u00d6tzi, a mummy from 5,000 years ago: Wierer, Ursula, Simona Arrighi, Stefano Bertola, G\u00fcnther Kaufmann, Benno Baumgarten, Annaluisa Pedrotti, Patrizia Pernter, and Jacques Pelegrin. 2018. \u201cThe Iceman\u2019s Lithic Toolkit: Raw Material, Technology, Typology and Use.\u201d <em>PLOS One<\/em> 13 (6): e0198292. https:\/\/doi.org\/10.1371\/journal.pone.0198292.<\/p>\n<h3><strong>Documentaries<\/strong><\/h3>\n<p>PBS NOVA series covering the expansion of modern <em>Homo sapiens<\/em> and interbreeding with archaic humans: Brown, Nicholas, dir. 2015. <em>First Peoples<\/em>. Edmonton: Wall to Wall Television. Amazon Prime Video.<\/p>\n<p>PBS NOVA special featuring the footprints found in White Sands National Park: Falk, Bella, dir. 2016. <em>Ice Age Footprints<\/em>. Boston: Windfall Films. https:\/\/www.pbs.org\/wgbh\/nova\/video\/ice-age-footprints\/.<\/p>\n<p>PBS NOVA special about how modern humans evolved adaptations to different environments. Shows how present-day people live around the world: Thompson, Niobe, dir. 2016. <em>Great Human Odyssey<\/em>. Edmonton: Clearwater Documentary. <a class=\"rId132\" href=\"https:\/\/www.pbs.org\/wgbh\/nova\/evolution\/great-human-odyssey.html\" target=\"_blank\">https:\/\/www.pbs.org\/wgbh\/nova\/evolution\/great-human-odyssey.html<\/a>.<\/p>\n<\/div>\n<h2 class=\"__UNKNOWN__\">References<\/h2>\n<div class=\"__UNKNOWN__\">\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Araujo, Bernardo B. A., Luiz Gustavo R. Oliveira-Santos, Matheus S. Lima-Ribeiro, Jos\u00e9 Alexandre F. 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Beaumont. 2012. \u201cEarly Evidence of San Material Culture Represented by Organic Artifacts from Border Cave, South Africa.\u201d <em>Proceedings of the National Academy of Sciences<\/em> 109 (33): 13214\u201313219.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">d\u2019Errico, Francesco, Christopher Henshilwood, Marian Vanhaeren, and Karen Van Niekerk. 2005. \u201cNassarius Kraussianus Shell Beads from Blombos Cave: Evidence for Symbolic Behaviour in the Middle Stone Age.\u201d <em>Journal of Human Evolution<\/em> 48 (1): 3\u201324.<\/p>\n<p class=\"import-Normal\">Dannemann, Michael, and Fernando Racimo. 2018. \u201cSomething Old, Something Borrowed: Admixture and Adaptation in Human Evolution.\u201d <em>Current Opinion in Genetics &amp; Development<\/em> 53: 1\u20138.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Day, M. 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Clark Howell. 2003. \u201cPleistocene <em>Homo sapiens<\/em> from Middle Awash, Ethiopia.\u201d <em>Nature<\/em> 423 (6941): 742\u2013747.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Woo, Ju-Kang. 1959. \u201cHuman Fossils Found in Liukiang, Kwangsi, China.\u201d <em>Vertebrata PalAsiatica<\/em> 3 (3): 109\u2013118.<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">Wu, XiuJie, Wu Liu, Wei Dong, JieMin Que, and YanFang Wang. 2008. \u201cThe Brain Morphology of Homo Liujiang Cranium Fossil by Three-Dimensional Computed Tomography.\u201d <em>Chinese Science Bulletin<\/em> 53 (16): 2513\u20132519.<\/p>\n<h2 class=\"import-Normal\">Acknowledgements<\/h2>\n<p class=\"import-Normal\" style=\"margin-left: 0pt;text-indent: 0pt\">I could not have undertaken this project without the help of many who got me to where I am today. I extend sincere thank yous to the many colleagues and former students who have inspired me to keep learning and talking about anthropology. Thank you also to all who are involved in this textbook project. The anonymous reviewers truly sparked improvements to the chapter. Lastly, the staff of Starbucks #5772 also contributed immensely to this text.<\/p>\n<\/div>\n<\/div>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><\/div>","protected":false},"author":96,"menu_order":30,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":["leslie-e-fitzpatrick"],"pb_section_license":""},"chapter-type":[],"contributor":[104],"license":[],"class_list":["post-1695","chapter","type-chapter","status-publish","hentry","contributor-leslie-e-fitzpatrick"],"part":20,"_links":{"self":[{"href":"https:\/\/opentextbooks.concordia.ca\/explorations3\/wp-json\/pressbooks\/v2\/chapters\/1695","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/opentextbooks.concordia.ca\/explorations3\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/opentextbooks.concordia.ca\/explorations3\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/opentextbooks.concordia.ca\/explorations3\/wp-json\/wp\/v2\/users\/96"}],"version-history":[{"count":6,"href":"https:\/\/opentextbooks.concordia.ca\/explorations3\/wp-json\/pressbooks\/v2\/chapters\/1695\/revisions"}],"predecessor-version":[{"id":1886,"href":"https:\/\/opentextbooks.concordia.ca\/explorations3\/wp-json\/pressbooks\/v2\/chapters\/1695\/revisions\/1886"}],"part":[{"href":"https:\/\/opentextbooks.concordia.ca\/explorations3\/wp-json\/pressbooks\/v2\/parts\/20"}],"metadata":[{"href":"https:\/\/opentextbooks.concordia.ca\/explorations3\/wp-json\/pressbooks\/v2\/chapters\/1695\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/opentextbooks.concordia.ca\/explorations3\/wp-json\/wp\/v2\/media?parent=1695"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/opentextbooks.concordia.ca\/explorations3\/wp-json\/pressbooks\/v2\/chapter-type?post=1695"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/opentextbooks.concordia.ca\/explorations3\/wp-json\/wp\/v2\/contributor?post=1695"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/opentextbooks.concordia.ca\/explorations3\/wp-json\/wp\/v2\/license?post=1695"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}