{"id":219,"date":"2023-05-24T21:41:50","date_gmt":"2023-05-25T01:41:50","guid":{"rendered":"https:\/\/opentextbooks.concordia.ca\/explorationsclone\/chapter\/6\/"},"modified":"2026-01-30T17:15:57","modified_gmt":"2026-01-30T22:15:57","slug":"6","status":"publish","type":"chapter","link":"https:\/\/opentextbooks.concordia.ca\/explorationsversiontwo\/chapter\/6\/","title":{"raw":"Primate Ecology and Behavior","rendered":"Primate Ecology and Behavior"},"content":{"raw":"<div class=\"__UNKNOWN__\">\r\n<p class=\"import-Normal\">Karin Enstam Jaffe, Ph.D., Sonoma State University<\/p>\r\n<p class=\"import-Normal\"><em>This chapter is a revision from <\/em><em>\"<\/em><a class=\"rId6\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-6\/\"><em>Chapter 6: Primate Ecology and Behavior<\/em><\/a><em>\u201d by Karin Enstam Jaffe. In <\/em><a class=\"rId7\" 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=\"rId8\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\"><em>CC BY-NC 4.0<\/em><\/a><em>. <\/em><\/p>\r\n\r\n<div class=\"textbox textbox--learning-objectives\"><header class=\"textbox__header\">\r\n<h2 class=\"textbox__title\"><span style=\"color: #000000\">Learning Objectives<\/span><\/h2>\r\n<\/header>\r\n<div class=\"textbox__content\">\r\n<ul>\r\n \t<li class=\"import-Normal\">Describe the variables that affect primate diets.<\/li>\r\n \t<li class=\"import-Normal\">Explain how primates interact with other organisms in their environment.<\/li>\r\n \t<li class=\"import-Normal\">Discuss why primates live in groups, types of primate groups, and components of their social systems.<\/li>\r\n \t<li class=\"import-Normal\">Describe the reproductive strategies of males and females.<\/li>\r\n \t<li class=\"import-Normal\">Explain the ways in which primates communicate.<\/li>\r\n \t<li class=\"import-Normal\">Discuss the evidence for primate cultural traditions.<\/li>\r\n<\/ul>\r\n<\/div>\r\n<\/div>\r\n<p class=\"import-Normal\">Nonhuman primates (hereafter, \u201cprimates\u201d) are a fascinating group of animals, whose similarity to humans can be striking. Because of this similarity, studying primates helps anthropologists to gain insight into how our human ancestors may have behaved. It also allows us to better understand our own behavior through <strong>[pb_glossary id=\"928\"]comparison[\/pb_glossary]<\/strong> (examining similarities and differences) with other primates as well as by comparing different species of primates to one another. In this way, studying primates helps anthropologists comprehend humanity from a biological perspective, which contributes to anthropology\u2019s commitment to <strong>[pb_glossary id=\"930\"]holism,[\/pb_glossary]<\/strong> the idea that the parts of a system interconnect and interact to make up the whole.<\/p>\r\n\r\n\r\n[caption id=\"\" align=\"alignleft\" width=\"242\"]<img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2023\/05\/image3.png\" alt=\"A person using binoculars to look at monkeys.\" width=\"242\" height=\"354\" \/> Figure 7.1: The author observing patas monkeys from a distance in Laikipia, Kenya. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-6\/\">Karin Enstam Jaffe observing patas monkeys in Laikipia, Kenya (Figure 6.5)<\/a> by Rebecca Chancellor is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\"> CC BY-NC 4.0 License<\/a>.[\/caption]\r\n\r\n<strong>[pb_glossary id=\"932\"]Ethology[\/pb_glossary] <\/strong>is the study of animal behavior, while <strong>[pb_glossary id=\"934\"]primatology [\/pb_glossary]<\/strong>is the study of primate behavior. People who study primates are called <strong>[pb_glossary id=\"936\"]primatologists[\/pb_glossary]<\/strong>. Research on primates can be conducted in the field (i.e., on wild primates) or in captivity (i.e., zoos) and may or may not involve experiments, such as playing recorded alarm calls to see how individuals react. Unlike some other Science, Technology, Engineering, and Math (STEM) fields, primatology has a long history of research conducted by women (see \u201cSpecial Topic: Women in Primatology\u201d). Primatologists come from many different disciplines, have diverse backgrounds, and study primates for different reasons. Biologists study primates as examples of evolutionary theories like natural selection, and to understand behaviors as <strong>[pb_glossary id=\"938\"]adaptations[\/pb_glossary]<\/strong>, or traits with a function that increases <strong>[pb_glossary id=\"940\"]fitness[\/pb_glossary]<\/strong>, i.e. an individual\u2019s survival and\/or reproduction. Primate intelligence is of interest to psychologists who want to learn more about deception or cooperation and to linguists interested in the principles of communication and language. Ecologists consider how primates interact with the habitats they occupy, and conservationists examine how primates are affected by deforestation, poaching, or illegal animal trade (see Appendix B: Primate Conservation for more information on these topics). Biological anthropologists, like myself (Figure 7.1), who study primates are interested in learning about their social complexity, and ecological and behavioral variation, to better understand the biological basis of human behavior. And, similar to biologists, we also explore how primate behavior is adaptive and contributes to individual fitness. Like other sciences, primatology is only as strong as its researchers, methods, and theories, and the field has benefitted recently from efforts to increase diversity and reckon with its colonialist past, as discussed below in \u201cSpecial Topic: Women in Primatology.\u201d\r\n<p class=\"import-Normal\">Humans share many traits in common with primates. As you learned in Chapter 5, some of these traits are similar due to <strong>[pb_glossary id=\"944\"]homology[\/pb_glossary]<\/strong>, traits both species inherited from a common primate ancestor. For example, like most other primates, humans are social animals who live in groups. Group living did not evolve independently in humans and other primates. Rather, group living is a trait that evolved in a primate ancestor, and because it benefited survival, it was retained in the species\u2019 <strong>[pb_glossary id=\"946\"]descendants[\/pb_glossary]<\/strong> (or the species that come after the ancestor species). In contrast, humans and other primates can have similar traits that evolved independently, which is called <strong>[pb_glossary id=\"948\"]analogy[\/pb_glossary]<\/strong>. For example, both humans and Japanese macaques (<em>Macaca fuscata<\/em>) use natural hot springs (Figures 7.2a-b). Research on these monkeys indicates that sitting in hot springs reduces stress and helps keep them warm, much as it does for humans (Takeshita et al. 2018). But this behavior is not the result of humans and Japanese macaques having a shared ancestor who used hot springs. Rather, the behavior arose independently in two species that both occupy northerly environments and adapted to cold climates using a similar behavior. Studying the homologous traits we share with other primates, like living in groups, helps us develop hypotheses about human behaviors as adaptations, which in turn helps us develop models for the behavior of our human ancestors. Studying analogous traits, like hot springs use, allows us to better understand the effects of ecological variables on morphology and behavior of both primates and humans, living and extinct.<\/p>\r\n\r\n\r\n[caption id=\"attachment_191\" align=\"aligncenter\" width=\"2161\"]<img class=\"wp-image-189 size-full\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/6.2.jpg\" alt=\"Left, a man in a hot spring. Right, monkeys in a hot spring.\" width=\"2161\" height=\"803\" \/> Figure 7.2a-b: Both humans (left) and Japanese macaques (right) use natural hot springs to reduce stress and relax. This similar trait arose independently in the two species, making it a good example of analogy. Credit: a. <a href=\"https:\/\/pixabay.com\/photos\/hot-spring-landscape-man-mountain-1846721\/\">Hot Spring Landscape<\/a> by <a href=\"https:\/\/pixabay.com\/users\/pexels-2286921\/?utm_source=link-attribution&amp;utm_medium=referral&amp;utm_campaign=image&amp;utm_content=1846721\">Pexels<\/a> has been modified (cropped) and has been designated to the <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/cc0\/\">public domain (CC0)<\/a> under a <a href=\"https:\/\/pixabay.com\/service\/terms\/#license\">Pixabay License<\/a>. b. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Jigokudani_hotspring_in_Nagano_Japan_001.jpg\">Jigokudani hotspring in Nagano Japan 001<\/a> by Yosemite is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/deed.en\"> CC BY-SA 3.0 License<\/a>.[\/caption]\r\n\r\n<div class=\"textbox\">\r\n<h2 class=\"import-Normal\">Special Topic: Women in Primatology<\/h2>\r\n<p class=\"import-Normal\">While many STEM fields have traditionally been, and continue to be, dominated by men, primatology has a long history of significant research conducted by women. This is due, in part, to the fact that three of the most well-known primatologists are women. In the early 1960s, British paleoanthropologist Louis Leakey (discussed in Chapters 9 and 10) was looking for students to study the great apes in hopes of shedding light on the behaviors of our early ancestors. He chose Jane Goodall (Figure 7.3a) to study chimpanzees (<em>Pan troglodytes<\/em>), Birute Galdikas (Figure 7.3b) to study Bornean orangutans (<em>Pongo pygmaeus<\/em>), and Dian Fossey (Figure 7.3c) to study mountain gorillas (<em>Gorilla<\/em><em> beringei beringei<\/em>). The work of these three women, sometimes referred to as Leakey\u2019s \u201cTrimates,\u201d has transformed our understanding of ape (and primate) behavior.<\/p>\r\n\r\n\r\n[caption id=\"attachment_190\" align=\"aligncenter\" width=\"626\"]<img class=\"wp-image-190\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/6.3-1.jpg\" alt=\"Jane Goodall, Birute Galdikas, and Dian Fossey.\" width=\"626\" height=\"209\" \/> Figure 7.3a-c: Louis Leakey\u2019s \u201cTrimates\u201d (left to right): a. Jane Goodall\u2019s research on the Gombe chimpanzees spans over half a century; b. Birute Galdikas\u2019s research and rescue work on behalf of orangutans spans 40 years; c. Dian Fossey studied mountain gorillas in Rwanda for almost 20 years, until her murder in 1985. Credit: a. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Jane_Goodall_HK.jpg\">Jane Goodall HK<\/a> by Jeekc has been modified (cropped) and is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\"> CC BY-SA 3.0 License<\/a>. b. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Dr_Birute_Galdikas.jpg\">Dr Birute Galdikas<\/a> by<a href=\"https:\/\/www.flickr.com\/photos\/sfupamr\/\"> Simon Fraser University - University Communications<\/a> has been modified (cropped) and is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/legalcode\"> CC BY 2.0 License<\/a>. c. <a href=\"https:\/\/www.flickr.com\/photos\/mary-lynn\/2925879356\">US-223658 Dian Fossey<\/a> by<a href=\"https:\/\/www.flickr.com\/photos\/mary-lynn\/2925879356\/\"> Mary-Lynn<\/a> has been modified (cropped) and is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/\"> CC BY 2.0 License<\/a>.[\/caption]\r\n<p class=\"import-Normal\">Arriving at the Gombe Stream Reserve in Tanzania in 1960, Jane Goodall was one of the first scientists to conduct a long-term study of wild nonhuman primates. Before then, most studies lasted less than a year and were often zoo-based. By 1961, she had made two astounding observations that forced us to reconsider what differentiates humans from the rest of the primate order. She observed chimpanzees eating a colobus monkey, the first reported evidence of meat eating in our closest relatives (she later observed them hunting and sharing meat). And she discovered that chimpanzees make and use tools by stripping leaves off twigs to \u201cfish\u201d for termites. Her work, spanning several decades, has produced long-term data on chimpanzee mating strategies, mother-infant bonds, and aggression. In the mid-1980s, Goodall transitioned from field researcher to conservationist and activist, advocating for the humane use of nonhuman animals (Stanford 2017).<\/p>\r\n<p class=\"import-Normal\">Birute Galdikas began her study of orangutans in Kalimantan, Borneo, in 1971. Hers was the first long-term study conducted on the Bornean orangutan. Galdikas and her colleagues have collected over 150,000 hours of observational data, focusing on the life histories of individual orangutans. While conducting behavioral research, Galdikas discovered that the pet trade and habitat loss were adversely affecting the orangutan population. Eventually, Galdikas\u2019s conservation efforts began to extend beyond advocacy and into rehabilitation and forest preservation (Bell 2017). If you would like to learn more about primate conservation efforts, please see Appendix B: Primate Conservation.<\/p>\r\n<p class=\"import-Normal\">In 1967, Dian Fossey began her long-term study of mountain gorillas and founded the Karisoke Research Center in Rwanda. Her and her colleagues\u2019 research, over several decades, revealed much about gorilla social behavior, ecology, and life history. Her efforts also led to the development of mountain gorilla conservation programs. However, she was a controversial figure, as discussed below. Fossey was murdered in December 1985; the case remains unsolved (Stewart 2017).<\/p>\r\n\r\n<h3 class=\"import-Normal\"><strong>Decolonizing Primatology<\/strong><\/h3>\r\n<p class=\"import-Normal\">Recently, the movement to <strong>[pb_glossary id=\"942\"]decolonize[\/pb_glossary]<\/strong> primatology, by understanding and highlighting the theories and research of non-Western individuals and perspectives, has gathered steam. This movement draws attention to the maltreatment of local people by Western primatologists. For example, Michelle Rodrigues (2019) argues that it's time we stop focusing on the scientific and conservation contributions of Dian Fossey and acknowledge that her \"active conservation\" techniques included kidnapping and torturing local Rwandans who were known as, or suspected to be, gorilla poachers. Rodrigues (2019) argues:<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 36pt;text-indent: 0pt\">The image of Fossey, a white American woman, whipping and torturing black African poachers is evocative of the behavior of white slaveholders in the American South. It is appalling enough to think of that behavior occurring in the 1850s; there is no way we can explain Fossey\u2019s behavior in the 1970s as the product of \u201ca different time.\u201d Yet, almost three decades later, the romantic notion of a noble martyr who died for her devotion to gorillas prevails, and these terrifying actions are often described as simply unorthodox methods. Perhaps these truths are softened due to fears that the reality of this legacy would harm gorilla conservation efforts. But memorializing her as a martyr and patron saint of gorilla conservation demands that we forget the cruel acts she advocated for and performed.<\/p>\r\n<p class=\"import-Normal\">Further, Louis Leakey\u2019s installment of Goodall, Galdikas, and Fossey to study chimpanzees, orangutans, and mountain gorillas, respectively, is itself viewed as recapitulating the colonial legacy in Africa and Asia. Given that Leakey was the offspring of British missionaries, Rodrigues (2019) argues, it is no accident that he was willing to mentor British and American women, while overlooking women from Africa and Asia as potential researchers. This leads us to another level of the decolonizing movement, which aims to highlight the research of non-Western primatologists, particularly those living in what primatologists refer to as \u201chabitat countries\u201d that are home to living primates. As you will see in this chapter, scientists from diverse backgrounds are active contributors to exciting research on primates around the world.<\/p>\r\n\r\n<\/div>\r\n<h2 class=\"import-Normal\">Ecology<\/h2>\r\n<p class=\"import-Normal\">The more than 600 species and subspecies of living primates are highly diverse in their dietary preferences and the habitats they occupy. In this section we\u2019ll briefly discuss aspects of <strong>[pb_glossary id=\"950\"]ecology[\/pb_glossary]<\/strong>, or the relationship between organisms and their physical surroundings, that impact a primate\u2019s life, the foods they eat, and the other species with whom they interact.<\/p>\r\n\r\n<h3 class=\"import-Normal\"><strong>Primate Diets<\/strong><\/h3>\r\n<p class=\"import-Normal\">Diet may be the most important variable influencing variation in primate morphology, behavior, and ecology. Most primates are <strong>[pb_glossary id=\"952\"]omnivores[\/pb_glossary]<\/strong> who ingest a variety of foods in order to obtain appropriate levels of protein, carbohydrates, fats, and fluids, but one type of food often makes up the majority of each species\u2019 diet. You learned about the dental and digestive adaptations of <strong>[pb_glossary id=\"954\"]frugivores[\/pb_glossary]<\/strong> (who feed primarily on fruit), <strong>[pb_glossary id=\"956\"]folivores[\/pb_glossary]<\/strong> (whose diet consists mostly of leaves), and <strong>[pb_glossary id=\"958\"]insectivores[\/pb_glossary] <\/strong>(who eat mainly insects) in Chapter 5, so we will not discuss them again here.<\/p>\r\n\r\n<h4 class=\"import-Normal\"><em>Body Size and Diet<\/em><\/h4>\r\n[caption id=\"attachment_191\" align=\"alignright\" width=\"559\"]<img class=\"wp-image-191\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/6.4-1.jpg\" alt=\"A tarsier eats a grasshopper. A gorilla eats leaves.\" width=\"559\" height=\"237\" \/> Figure 7.4a-b: Primates eat different types of food. Small primates, like the spectral tarsier (left), eat mostly insects while large primates, like the mountain gorilla (right), eat mostly leaves. Credit: a. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Spectral_Tarsier_Tarsius_tarsier_(7911549768).jpg\">Spectral Tarsier Tarsius tarsier (7911549768)<\/a> by<a href=\"https:\/\/www.flickr.com\/people\/65695019@N07\"> Bernard DUPONT<\/a> has been modified (cropped) and is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\"> CC BY-SA 2.0 License<\/a>. b. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Mountain_gorilla_(Gorilla_beringei_beringei)_eating.jpg\">Mountain gorilla (Gorilla beringei beringei) eating<\/a> by<a href=\"https:\/\/www.sharpphotography.co.uk\/\"> Charles J Sharp<\/a> (creator QS:P170,Q54800218) has been modified (cropped) and is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\"> CC BY-SA 4.0 License<\/a>.[\/caption]\r\n\r\nInsects are a high-quality food, full of easily digestible protein and high in calories that meet most of a primate\u2019s dietary needs. Although all primates will eat insects if they come upon them, those species that rely most heavily on insects tend to be the smallest. Why? Because larger primates simply cannot capture and consume enough insects every day to survive. Because of their small size (less than 150 g), spectral tarsiers (<em>Tarsius spectrum<\/em>) have a fast <strong>[pb_glossary id=\"960\"]metabolism[\/pb_glossary]<\/strong>, which means they turn food to energy quickly, but they do not need to consume large amounts of food each day. It does not matter to a spectral tarsier that a grasshopper only weighs 300 mg, because the tarsier (<em>Tarsius<\/em>) itself is so small that one grasshopper is a good-size meal (Figure 7.4a). That same grasshopper is not even a snack for an adult male mountain gorilla (<em>Gorilla beringei beringei<\/em>), who may weigh up to 200 kg. Fortunately for gorillas (<em>Gorilla)<\/em>, their large body size means they have a slow metabolism, converting food into energy much more slowly, so they can eat lower quality food that takes longer to digest, provided there is a lot of it. For gorillas, leaves, which are hard to digest but plentiful, fit the bill (Figure 7.4b). Most medium-sized primates are highly frugivorous, and supplement their fruit based diet in ways that correspond with their size: Smaller frugivores tend to supplement with insects, while larger frugivores tend to supplement with leaves.\r\n\r\n<\/div>\r\n<div class=\"__UNKNOWN__\">\r\n<h4 class=\"import-Normal\"><em>Food Abundance and Distribution<\/em><\/h4>\r\n<p class=\"import-Normal\">Nutrients are not the only dietary considerations primates must make. They must also ensure that they consume more calories than they use. The abundance and distribution of food affect energy expenditure and calorie intake because they determine how far animals must travel in search of food and how much they must compete to obtain it. <strong>[pb_glossary id=\"962\"]Abundance[\/pb_glossary] <\/strong>refers to how much food is available in a given area while <strong>[pb_glossary id=\"964\"]distribution[\/pb_glossary]<\/strong> refers to how food is spread out. In terms of abundance, food is either plentiful or scarce (Figure 7.5a\u2013b). Food is distributed in one of three ways: uniformly (Figure 7.6a), in clumps (Figure 7.6b), or randomly (Figure 7.6c). In general, higher-quality foods, like fruit and insects, are less abundant and have patchier distributions than lower-quality foods, like leaves. Primates who eat fruit or insects usually have to travel farther to find food and burn more calories in the process. Abundance and distribution of food is another reason why larger primates tend to rely more heavily on leaves than either fruit or insects.<\/p>\r\n\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"619\"]<img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image2-2.png\" alt=\"Two squares with different amounts of dots. \" width=\"619\" height=\"286\" \/> Figure 7.5a-b: Two types of food abundance. Food is plentiful when there is a lot of it in a given area (left). Food is scarce when there is not very much of it in a given area (right). Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-6\/\">Food abundance and food scarcity (Figure 6.7)<\/a> by Karin Enstam Jaffe 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]\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"690\"]<img style=\"font-size: 1em\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image4-2.png\" alt=\"Three squares with dots in different formations. \" width=\"690\" height=\"214\" \/> Figure 7.6a-c: Three types of food distribution. a. Food has a uniform distribution when it is spread out evenly in the environment. b. Food has a clumped distribution when it is found in patches. c. Food is randomly distributed when it has neither uniform nor clumped distribution. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-6\/\">Food distribution patterns (Figure 6.8)<\/a> by Karin Enstam Jaffe 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]\r\n<h3 class=\"import-Normal\"><strong>Community Ecology<\/strong><\/h3>\r\n<p class=\"import-Normal\">Primates are members of broader ecological communities composed of other species, including other primates, predators, parasites, and even humans. <strong>[pb_glossary id=\"966\"]Community ecology[\/pb_glossary]<\/strong> deals with the relationships and interactions between different organisms that occupy the same habitat. Interactions with <strong>[pb_glossary id=\"968\"]conspecifics[\/pb_glossary] <\/strong>(members of the same species) and <strong>[pb_glossary id=\"970\"]heterospecifics[\/pb_glossary]<\/strong> (members of different species) are critical aspects of ecological communities. Some habitats support highly diverse <strong>[pb_glossary id=\"972\"]primate communities[\/pb_glossary]<\/strong> consisting of 10 or more primate species. How can so many primate species occupy the same area and avoid competition? In most cases, the primate species that live together occupy different <strong>[pb_glossary id=\"974\"]niches[\/pb_glossary]<\/strong>, which means they do not meet their needs for food and shelter in the exact same way. Two species can avoid competition by eating different kinds of food, living at different levels of a forest, or even searching for food at different times of day. Because tropical rainforests, like Manu National Park in Peru, are highly variable, with many habitats and many sources of food and shelter, there are many different niches for multiple species to exploit, and large primate communities can result (Figure 7.7).<\/p>\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"710\"]<img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image5-1-1.png\" alt=\"Eight primate species.\" width=\"710\" height=\"550\" \/> Figure 7.7: Eight of the 14 primate species in Manu National Park, Peru. Top row, left to right: Goeldi\u2019s marmoset (Callimico goeldi), Rio Tapaj\u00f3s saki (Pithecia irrorata), tufted capuchin (Sapajus apella); middle row, left to right: emperor tamarin (Saguinus imperator), black-headed night monkey (Aotus nigriceps), Bolivian red howler (Alouatta sara); bottom row, left to right: black-capped squirrel monkey (Saimiri boliviensis), Peruvian spider monkey (Ateles chamek). Credit: Primate species in Manu National Park original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Karin Jaffe 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:\/\/www.flickr.com\/photos\/31223088@N08\/5582747190\/\">Tamarin Baby\/Goeldi\u2019s Monkey<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/31223088@N08\/\">stefan_fotos<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/\">CC BY 2.0 License<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Pithecia_irrorata_-Brazil-8b.jpg\">Pithecia irrorata -Brazil-8b<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/9092428@N04\">Ana_Cotta<\/a>, modified (cropped), <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/deed.en\">CC BY 2.0 License<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Tufted_capuchin_on_a_branch_in_Singapore.jpg\">Tufted Capuchin on a Branch in Singapor<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Basile_Morin\">Basile_Morin<\/a>, modified (cropped), <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/deed.en\">CC BY-SA 4.0 License<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Tamarin_portrait.JPG\">Tamarin Portrait<\/a> by <a href=\"https:\/\/sites.google.com\/site\/thebrockeninglory\/?pli=1\">Brocken Inaglory<\/a>, modified (cropped), <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/deed.en\">CC BY-SA 3.0 License<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Aotus_nigriceps_1.jpg\">Aotus nigriceps 1<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/dusantos_bh\/\">DuSantos<\/a>, modified (cropped), <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/deed.en\">CC BY 2.0 License<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Alouatta_sara_%28Bolivian_red_howler%29.jpg\">Aloutta sara (Bolivian Red Howler)<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/nacho_dayz\/\">Raul Ignacio<\/a>, modified (cropped), <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/\">CC BY-SA 2.0 License<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Black-capped_squirrel_monkey_%28Chalalan%29.jpg\">Black-Capped Squirrel Monkey (Chalalan)<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Rodrigo_Mariaca\">Rodrigo Mariaca<\/a>, modified (cropped), <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/deed.en\">CC BY-SA 4.0 License<\/a>; <a href=\"https:\/\/www.flickr.com\/photos\/eye1\/3185562151\/\">Maquisapa (Spider Monkey)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/eye1\/\">Ivan Mlinaric<\/a>, modified (cropped), <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/\">CC BY 2.0 License<\/a>].[\/caption]\r\n<h4 class=\"import-Normal\"><em>Competitive Interactions<\/em><\/h4>\r\n<p class=\"import-Normal\">Although species living in the same location often occupy different niches to avoid competition, when a resource that is important for survival or reproduction is scarce, individuals will compete to obtain that resource. This is a central tenet of Charles Darwin\u2019s theory of evolution by natural selection (see Chapter 2). Competition between primates takes two forms: Individuals engage in <strong>[pb_glossary id=\"976\"]direct competition[\/pb_glossary]<\/strong>, which involves physical interaction between individuals (such as fighting), over resources that are large and worth defending (fruit is a good example of a food resource over which primates will fight). Individuals engage in <strong>[pb_glossary id=\"978\"]indirect competition[\/pb_glossary]<\/strong>, in which there is no physical interaction between individuals, when a resource is small. Primates often engage in indirect competition for insects, like grasshoppers, that are eaten quickly, often before another individual arrives on the scene. Primates may engage in direct and\/or indirect competition with members of their own group, with members of other groups of conspecifics, or with heterospecifics.<\/p>\r\n\r\n<h4 class=\"import-Normal\"><em>Predator-Prey Interactions<\/em><\/h4>\r\n<p class=\"import-Normal\">The plants and animals that primates eat are an important part of their ecological community. In addition to insects, many primates incorporate some <strong>[pb_glossary id=\"980\"]vertebrate[\/pb_glossary]<\/strong> (animals with an internal spinal column or backbone) prey into their diet. Often, predation by primates is opportunistic, occurring because the prey happens to be in the right place at the right time. I\u2019ve observed vervets (<em>Chlorocebus pygerythrus<\/em>) opportunistically killing lizards by smashing them against a rock or tree trunk and eating them. More rarely, hunting is deliberate and cooperative. In some chimpanzee (<em>Pan troglodytes<\/em>) populations, hunts involve multiple individuals, each of whom plays a specific role and is rewarded afterward with a share of the prey that has been captured (Samuni et al. 2018).<\/p>\r\n<p class=\"import-Normal\">All primates are susceptible to predation by mammalian <strong>[pb_glossary id=\"982\"]carnivores[\/pb_glossary] <\/strong>(animals whose diet consists primarily of animal tissue (e.g., Figure 7.8a), reptiles (e.g., Figure 7.8b), or birds of prey (e.g., Figure 7.8c). Although the specific predators found in an ecological community differ based on geography, smaller primates always fall prey to a wider range of predators. Because predators are diverse in their hunting tactics, primates have evolved a wide range of tactics to avoid or escape them. We will discuss some of these behavioral adaptations later in this chapter in the section titled \u201cWhy Do Primates Live in Groups?.\u201d<\/p>\r\n&nbsp;\r\n\r\n<\/div>\r\n\r\n[caption id=\"attachment_210\" align=\"aligncenter\" width=\"765\"]<img class=\"wp-image-195\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/6.8-scaled-1.jpg\" alt=\"A leopard, python, and harpy eagle.\" width=\"765\" height=\"229\" \/> Figure 7.8a-c: Examples of primate predators: the Indian leopard (Panthera fusca) is an example of a mammalian carnivore (top left), the South African python (Python natalensis) is an example of a reptilian predator (bottom left), and the harpy eagle (Harpia harpyja) of Central and South America is an example of a bird of prey (right). Credit: a. <a href=\"https:\/\/www.flickr.com\/photos\/srikaanth-sekar\/9814267145\/\">Leopard<\/a> by<a href=\"https:\/\/www.flickr.com\/people\/srikaanth-sekar\/\"> Srikaanth Sekar<\/a> has been modified (cropped) and is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/\"> CC BY-SA 2.0 License<\/a>. b. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Python_natalensis_G._J._Alexander.JPG\">Python natalensis G. J. Alexander<\/a> by Graham J. Alexander, University of the Witwatersrand, USGS, is in the<a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\"> public domain<\/a>. c. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Harpy_Eagle_clutching_captured_bird_-_Itirapina_Reserve.jpg\">Harpy Eagle clutching captured bird - Itirapina Reserve<\/a> by Jonathan Wilkins has been modified (cropped) and is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/deed.en\">CC BY-SA 3.0 License<\/a>.[\/caption]\r\n\r\n<div class=\"__UNKNOWN__\">\r\n<h4 class=\"import-Normal\"><em>Mutualistic Interactions<\/em><\/h4>\r\n<p class=\"import-Normal\">So far, we've discussed competitive and predator-prey interactions in primate communities. But there are some interactions (between different primate species and between primates and other species) that are <strong>[pb_glossary id=\"984\"]mutualistic[\/pb_glossary]<\/strong>, which is when organisms of different species work together, each benefiting from the interaction or relationship. One example is <strong>[pb_glossary id=\"986\"]seed dispersal[\/pb_glossary]<\/strong>, which is the process by which seeds move away from the plant that produced them in preparation for germination and becoming a new plant. When seeds are dispersed by animals, like primates, it is an example of mutualism. The primate eats the fruit of a plant, which provides nutrients for its body, and in the process ingests the plant\u2019s seeds. Later, it deposits the seeds at another location as a pile of fertilizer.<\/p>\r\n<p class=\"import-Normal\">Another example of mutualism is <strong>[pb_glossary id=\"988\"]polyspecific associations[\/pb_glossary]<\/strong>, which are associations between two or more different species that are maintained by behavioral changes by at least one of the species. While some associations are short in duration, others are semi-permanent. The mutualistic benefits of polyspecific associations include one species gaining access to food that would otherwise have been inaccessible or being alerted to the presence of predators that they would not have not have known were present otherwise. In some cases, individuals seem to recognize and seek out specific members of another species. Twenty years of observations on chimpanzees and Western lowland gorillas (<em>Gorilla gorilla gorilla<\/em>) in the Republic of Congo has revealed social ties (some might call them friendships) between individual chimpanzees and gorillas that last for years and occur in a variety of social contexts, including play (Sanz et al. 2022).<\/p>\r\n\r\n<h4 class=\"import-Normal\"><em>Parasite-Host Interactions<\/em><\/h4>\r\n<p class=\"import-Normal\">Primates are hosts for a variety of <strong>[pb_glossary id=\"990\"]parasites[\/pb_glossary]<\/strong>, which are organisms that live in or on another organism (the host). Parasites come in many forms and pose varying levels of danger to the host. Blood parasites cause diseases like yellow fever and malaria. Skin parasites include fleas and ticks, which feed on the host\u2019s blood, and botflies, which lay eggs in the host\u2019s flesh. Bot fly larvae feed on the host\u2019s flesh as they develop and eventually (if not removed) break through the skin at maturity. Gut parasites, like tapeworms, get into the intestines and feed off of the food that is being digested by the host. Because most primates live in groups (see the \u201cPrimate Societies\u201d section of this chapter), the tendency for <strong>[pb_glossary id=\"992\"]social transmission[\/pb_glossary]<\/strong> of parasites, or the transfer of parasites from one individual to another, is high. Primates have evolved mechanisms to avoid parasite infection, including switching sleeping and feeding sites so as to avoid parasites. Mandrills (<em>Mandrillus sphinx<\/em>) have been shown to avoid grooming infected conspecifics as well as to avoid their feces, which smell different than the feces of individuals who are not infected with parasites (Poirotte et al. 2017). Other primates, including chimpanzees, appear to self-medicate when infected with parasites by ingesting plants that have antiparasitic properties (Krief et al. 2005).<\/p>\r\n\r\n<h4 class=\"import-Normal\"><em>Human-Primate Interactions<\/em><\/h4>\r\n<p class=\"import-Normal\">Humans are part of many primate communities and our relationship with our closest relatives is often complicated. In some areas, humans hunt primates for their meat or as trophies, or so they can sell the infants as pets. As the human population increases in size, our demand for natural resources, like wood to build houses or land on which to grow food, also increases, often at the expense of pristine primate (and other animal) habitat. As their natural habitat shrinks, primates search for food in areas occupied by humans and may be shot as crop-raiding pests. While deforestation, hunting, and the pet trade are examples of ways in which humans negatively affect the lives of primates, some human-primate interactions are beneficial. In some parts of the world primates are central to <strong>[pb_glossary id=\"994\"]ecotourism[\/pb_glossary]<\/strong>, which focuses on nature-based attractions to educate tourists and uses economically and ecologically sustainable practices. Perhaps one of the greatest success stories of ecotourism involves the mountain gorillas of Rwanda (see Figure 7.4b). After internal conflict plagued Rwanda during the 1990s, the Virunga Mountains area developed gorilla-based tourism to aid in socioeconomic development and to bring stability to the region. This process not only helped to increase mountain gorilla populations but was also able to generate enough income to cover the operation costs of three national parks and provide income and other benefits to people living in the area (Maekawa et al. 2013). You can learn more about human-primate interactions in Appendix B: Primate Conservation.<\/p>\r\n\r\n<h2 class=\"import-Normal\">Primate Societies<\/h2>\r\n<p class=\"import-Normal\">Unlike many other animals, primates are highly social and many live in stable groups consisting of adult males and females, even outside the<strong> [pb_glossary id=\"996\"]breeding season[\/pb_glossary]<\/strong>, when females are <strong>[pb_glossary id=\"998\"]receptive[\/pb_glossary]<\/strong> and available for mating because they are not pregnant or nursing. Indeed, <strong>[pb_glossary id=\"1000\"]sociality[\/pb_glossary]<\/strong>, or the tendency to form social groups, is a key behavioral adaptation of the order primates (see Chapter 5). This has led primatologists to ask two questions: \u201cWhy do primates live in groups?\u201d and \u201cWhat types of groups do primates live in?\u201d<\/p>\r\n\r\n<h3 class=\"import-Normal\"><strong>Why Do Primates Live in Groups?<\/strong><\/h3>\r\n<p class=\"import-Normal\">Primates live in groups when the benefits of doing so exceed the costs. Although there are many potential benefits to group living, enhanced feeding competition and predator avoidance are important benefits for many group living primates. When primates feed on high-quality, scarce food (like fruit), larger groups are more successful in competition with other groups. For example, in a long-term study of vervets in Kenya\u2019s Amboseli National Park, larger vervet groups had larger and better <strong>[pb_glossary id=\"1002\"]home ranges[\/pb_glossary]<\/strong>, which is the area in which a group regularly moves around as it performs its daily activities, including searching for food and water. Females in larger groups had higher average infant and female survival rates than the smallest group. Because pregnancy and nursing are energetically expensive for females, female <strong>[pb_glossary id=\"1004\"]reproductive success[\/pb_glossary]<\/strong>, or genetic contribution to future generations (measured by the number of offspring produced), is limited by access to food. Although living in a group means females compete with members of their own group for food, the benefits of being a member of a larger vervet group outweigh the costs (Cheney and Seyfarth 1987).<\/p>\r\n<p class=\"import-Normal\">However, because they contain more individuals, larger groups are more likely to attract the attention of predators compared to smaller groups. This is one of the reasons that primates who rely on <strong>[pb_glossary id=\"1006\"]crypsis[\/pb_glossary]<\/strong>, or the ability to avoid detection by others, including predators, are often <strong>[pb_glossary id=\"1008\"]solitary[\/pb_glossary] <\/strong>(the term used to describe individuals who do not live together with other members of their species) and <strong>[pb_glossary id=\"1010\"]nocturnal[\/pb_glossary]<\/strong>, or active at night. If an animal is already hard to see because it is active at night, then moving quietly in small groups is a good strategy to avoid detection by predators. The slow loris (<em>Nycticebus coucang<\/em>) of Southeast Asia is a good example of this strategy (Figure 7.9a). Nocturnal and solitary, the slow loris moves slowly and quietly as its primary strategy to avoid detection (Wiens and Zitzmann 2003). In contrast, primates who live in large groups and are <strong>[pb_glossary id=\"1012\"]diurnal[\/pb_glossary]<\/strong>, or active during the day (like gelada baboons [<em>Theropithecus gelada<\/em>]; Figure 7.9b) cannot avoid detection by predators. Instead, group-living primates rely on behaviors that alert others to the presence of danger and\/or deter predators, including shared <strong>[pb_glossary id=\"1014\"]vigilance[\/pb_glossary]<\/strong> (watchful behavior to detect potential danger), <strong>[pb_glossary id=\"1016\"]mobbing[\/pb_glossary]<\/strong> (the act of cooperatively attacking or harassing a predator), and <strong>[pb_glossary id=\"1018\"]alarm calling[\/pb_glossary]<\/strong> (vocalizations emitted by social animals in response to danger). We will discuss alarm calls in the Communication section.<\/p>\r\n\r\n\r\n[caption id=\"attachment_196\" align=\"aligncenter\" width=\"761\"]<img class=\"wp-image-196\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/6.9.jpg\" alt=\"A slow loris. A group of gelada baboons.\" width=\"761\" height=\"269\" \/> Figure 7.9a-b: Some primates, like the slow loris (left), are solitary and spend most of their time alone. However, most primates, like the gelada baboon (right), live in groups of varying sizes. Credit: a. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Slow_Loris.jpg\">Slow Loris<\/a> by Jmiksanek is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\"> CC BY-SA 3.0 License<\/a>. b. <a href=\"https:\/\/www.flickr.com\/photos\/39997856@N03\/7588490544\">Field of baboons<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/39997856@N03\/\">mariusz kluzniak<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-nd\/2.0\/\">CC BY-NC-ND 2.0 License<\/a>.[\/caption]\r\n<h3 class=\"import-Normal\"><strong>What Types of Groups Do Primates Live In? <\/strong><\/h3>\r\n<p class=\"import-Normal\">Primates vary with regard to the types of groups in which they live. A <strong>[pb_glossary id=\"1020\"]social system[\/pb_glossary] <\/strong>describes a set of social interactions and behaviors that is typical for a species. The components that make up a species\u2019 social system include:<\/p>\r\n\r\n<ul>\r\n \t<li class=\"import-Normal\">Group size, which refers to the number of individuals that typically live together. Primate group size can be highly variable, ranging from one or a few individuals, to a few dozen, upward to several hundred individuals.<\/li>\r\n \t<li class=\"import-Normal\">Group composition describes group membership in terms of age class (e.g., adult, juvenile, infant) and sex. In some primates, groups consist of a mother and her dependent offspring while in others, one adult male lives long-term with one adult female and their dependent offspring. In other species, one or more adult males live with multiple females and their offspring.<\/li>\r\n \t<li class=\"import-Normal\">A species\u2019 <strong style=\"text-align: initial;text-indent: 18pt;font-size: 1em\">[pb_glossary id=\"1022\"]mating system[\/pb_glossary]<\/strong><span style=\"text-align: initial;text-indent: 18pt;font-size: 1em\"> refers to which male(s) and female(s) mate. The terms that describe a mating system (e.g., <\/span><strong style=\"text-align: initial;text-indent: 18pt;font-size: 1em\">[pb_glossary id=\"1024\"]polygyny[\/pb_glossary]<\/strong><span style=\"text-align: initial;text-indent: 18pt;font-size: 1em\">, in which one male mates with multiple females) are sometimes used to describe a primate species\u2019 social system, but a mating system is one component of the species\u2019 social system. For example, two species might both have polygynous mating systems, but in one species, the group is composed of one male and multiple females, while members of the other species live as solitary individuals.<\/span><\/li>\r\n \t<li class=\"import-Normal\"><strong style=\"text-align: initial;text-indent: 18pt;font-size: 1em\">[pb_glossary id=\"1026\"]Ranging behavior[\/pb_glossary] <\/strong><span style=\"text-align: initial;text-indent: 18pt;font-size: 1em\">refers to the way in which animals move about their environment. Most primate species have a home range, where they perform their daily activities. Some primates defend a <\/span><strong style=\"text-align: initial;text-indent: 18pt;font-size: 1em\">[pb_glossary id=\"1028\"]territory[\/pb_glossary]<\/strong><span style=\"text-align: initial;text-indent: 18pt;font-size: 1em\"> which is the part of the home range that the group actively guards in an attempt to keep out conspecifics.<\/span><\/li>\r\n \t<li class=\"import-Normal\"><strong style=\"text-align: initial;text-indent: 18pt;font-size: 1em\">[pb_glossary id=\"1030\"]Dispersal[\/pb_glossary] <\/strong><span style=\"text-align: initial;text-indent: 18pt;font-size: 1em\">patterns describe which sex moves to a new group to reproduce. In most primate species, males disperse because the benefits of dispersal, including increased access to mates and reduced competition from other males, outweigh the costs of migrating into a new group, which often comes with aggression from current group members. For many female primates, the opposite is true: females usually benefit from remaining <\/span><strong style=\"text-align: initial;text-indent: 18pt;font-size: 1em\">[pb_glossary id=\"1032\"]philopatric[\/pb_glossary]<\/strong><span style=\"text-align: initial;text-indent: 18pt;font-size: 1em\">, or in the group of their birth. This allows them to maintain strong alliances with female relatives, which helps them compete successfully against other groups for food. In solitary species, offspring of both sexes leave their mother\u2019s home range and become solitary. If this did not happen, the species would not be solitary. Even though both sexes disperse in solitary species, males usually disperse farther than females.<\/span><\/li>\r\n \t<li class=\"import-Normal\">Social interactions describe the ways in which individuals interact with members of their own and other groups of conspecifics. <strong style=\"text-align: initial;text-indent: 18pt;font-size: 1em\">[pb_glossary id=\"1034\"]Affiliative[\/pb_glossary] <\/strong><span style=\"text-align: initial;text-indent: 18pt;font-size: 1em\">(i.e., friendly or nonaggressive) behaviors include <\/span><strong style=\"text-align: initial;text-indent: 18pt;font-size: 1em\">[pb_glossary id=\"1036\"]grooming[\/pb_glossary]<\/strong><span style=\"text-align: initial;text-indent: 18pt;font-size: 1em\"> (picking through the fur of another individual), playing, or <\/span><strong style=\"text-align: initial;text-indent: 18pt;font-size: 1em\">[pb_glossary id=\"1038\"]coalitions[\/pb_glossary] <\/strong><span style=\"text-align: initial;text-indent: 18pt;font-size: 1em\">(temporary alliances between individuals). <\/span><strong style=\"text-align: initial;text-indent: 18pt;font-size: 1em\">[pb_glossary id=\"1040\"]Agonistic[\/pb_glossary]<\/strong><span style=\"text-align: initial;text-indent: 18pt;font-size: 1em\"> (i.e., aggressive) behaviors include fighting over food or fighting over access to mates. In groups that contain multiple adult individuals of the same sex, it is common to have a <\/span><strong style=\"text-align: initial;text-indent: 18pt;font-size: 1em\">[pb_glossary id=\"1042\"]dominance hierarchy[\/pb_glossary]<\/strong><span style=\"text-align: initial;text-indent: 18pt;font-size: 1em\">, or a group of individuals that can be ranked according to their relative amount of power over others in the hierarchy. Initially, dominance hierarchies are established through the outcome of conflicts. Individuals who lose conflicts with others are <\/span><strong style=\"text-align: initial;text-indent: 18pt;font-size: 1em\">[pb_glossary id=\"1044\"]subordinate[\/pb_glossary]<\/strong><span style=\"text-align: initial;text-indent: 18pt;font-size: 1em\"> (or low rank) to those who win them. Those who win conflicts are <\/span><strong style=\"text-align: initial;text-indent: 18pt;font-size: 1em\">[pb_glossary id=\"744\"]dominant[\/pb_glossary] <\/strong><span style=\"text-align: initial;text-indent: 18pt;font-size: 1em\">(or high rank). Dominant individuals gain access to resources, like food or mates, before subordinates. Once a hierarchy is established, agonism decreases because everyone \u201cknows their place.\u201d<\/span><\/li>\r\n<\/ul>\r\n<p class=\"import-Normal\">The main types of primate social systems are as follows: solitary; single-male, single-female; single-male, multi-female; multi-male, multi-female; fission-fusion; and multi-male, single-female. These types are discussed below.<\/p>\r\n\r\n<h4 class=\"import-Normal\"><em>Solitary<\/em><\/h4>\r\n<p class=\"import-Normal\">Recall that the term <em>solitary<\/em> is used to describe species in which individuals do not live or travel together with other members of the same species, except for mothers and unweaned offspring. Males typically occupy a large home range or territory that overlaps the home ranges of multiple females, with whom they mate (Figure 7.10a). Because one male mates with multiple females, the mating system of solitary primates is polygyny. Social interactions between adults are limited but because some males do not get to mate, competition between males is intense. When males compete physically, they benefit from large body size and weaponry. The result is<strong> [pb_glossary id=\"1046\"]sexual dimorphism[\/pb_glossary]<\/strong>, when males and females look different from one another. Both males and females disperse, although males move farther from their mother than females. The nocturnal West African potto (<em>Perodicticus <\/em><em>potto<\/em>; Figure 7.10b) is solitary. Bornean orangutans, which are diurnal, are also solitary.<\/p>\r\n\r\n<\/div>\r\n&nbsp;\r\n\r\n[caption id=\"attachment_210\" align=\"aligncenter\" width=\"620\"]<img class=\"wp-image-197\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/6.10-01-1.jpg\" alt=\"Grouping pattern description is available in caption. A potto in a tree at night also shown.\" width=\"620\" height=\"272\" \/> Figure 7.10a-b: Illustration of a solitary species\u2019 grouping pattern is shown on the left. Key: square = adult male; dot = adult female; open circle represents the outline of the male\u2019s home range; open oval represents individual female home ranges. The West African potto is a solitary primate (right). <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. Polygyny in a Solitary Social System original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Karin Enstam Jaffe is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\"> CC BY-NC 4.0 License<\/a>. b. <a href=\"https:\/\/www.flickr.com\/photos\/nikborrow\/31307385633\">West African Potto Perodicticus potto Kakum National Park, Ghana<\/a> by<a href=\"https:\/\/www.flickr.com\/people\/nikborrow\/\"> Nik Barrow<\/a> has been modified (cropped) and is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/2.0\/\"> CC BY-NC 2.0 License<\/a>.[\/caption]\r\n\r\n<div class=\"__UNKNOWN__\">\r\n<h4 class=\"import-Normal\"><em>Single-Male, Single-Female<\/em><\/h4>\r\n<p class=\"import-Normal\">Primate species in which an adult male and adult female live together with their dependent offspring have a <strong>[pb_glossary id=\"1048\"]single-male, single-female[\/pb_glossary]<\/strong> social system, sometimes referred to as a \u201cfamily,\u201d with group sizes between two and five individuals. The adult male and adult female engage in behaviors that strengthen their social relationship, or <strong>[pb_glossary id=\"1050\"]pair bond[\/pb_glossary]<\/strong>, including mutual grooming and resting together. The pair defend a territory (Figure 7.11a) and keep same-sex individuals away from their mate. The adult male and adult female mate with each other, so the mating system is <strong>[pb_glossary id=\"1052\"]monogamy[\/pb_glossary]<\/strong>, although mating outside the pair bond may occur. Species with monogamous mating systems are usually <strong>[pb_glossary id=\"1054\"]sexually monomorphic[\/pb_glossary]<\/strong> (males and females look similar) because competition for mates is relaxed since most males are able to obtain a mate. Males are usually confident that they are the father of their mate\u2019s infant, so they help with offspring care by carrying the infant when it is not nursing. Once offspring are sexually mature, both males and females disperse. As with solitary species, males disperse farther from their parents than females. Bolivian Gray titi monkeys (<em>Plecturocebus donacophilus<\/em>) are an example of a species that has a single-male, single-female social system. One of their signature behaviors is tail twining, when two individuals sit with their tails wrapped around each other (Figure 7.11b). This behavior reinforces the social bond among family members and is especially common between the adult male and female. Gibbons (<em>Hylobates<\/em>) and owl monkeys (<em>Aotus<\/em>) also live in single-male, single-female groups.<\/p>\r\n\r\n\r\n[caption id=\"attachment_198\" align=\"aligncenter\" width=\"608\"]<img class=\"wp-image-198\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/6.11-01.jpg\" alt=\"Left: Circle contains one dot (female) and one square (male). Right: Two titi monkeys.\" width=\"608\" height=\"357\" \/> Figure 7.11a-b: Illustration of a single-male, single-female grouping pattern is shown on the left. Key: square = adult male; dot = adult female; open circle represents the outline of the group\u2019s territory, which the bonded pair defend against conspecifics. The titi monkey (right) is an example of a primate species with a single-male, single-female social system. Credit: a. Single-Male, Single-Female Social System original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Karin Enstam Jaffe is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\"> CC BY-NC 4.0 License<\/a>. b. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Callicebus-brunneus-London-Zoo.jpg\">Two Red Titi Monkeys (Callicebus cupreus) sitting together with their tails intertwined at the London Zoo<\/a> by<a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Stevenj\"> Steven G. Johnson<\/a> has been modified (cropped) and is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/deed.en\"> CC BY-SA 3.0 License<\/a>.[\/caption]\r\n\r\n<\/div>\r\n<div class=\"__UNKNOWN__\">\r\n<h4 class=\"import-Normal\"><em>Single-Male, Multi-Female<\/em><\/h4>\r\n<p class=\"import-Normal\"><strong>[pb_glossary id=\"1056\"]Single-male, multi-female[\/pb_glossary]<\/strong> groups consist of one adult male living with multiple adult females and their dependent offspring (Figure 7.12a ) . These groups can range from as few as five or ten individuals to as many as 50. Female social relationships are governed by the female dominance hierarchy. Females are usually philopatric and males disperse. Males who are unable to join a group of females may join a bachelor group with other males. Because a single male mates with multiple females, the mating system is polygyny. Species that form single-male, multi-female groups may or may not defend a territory, but the <strong>[pb_glossary id=\"1058\"]resident male[\/pb_glossary]<\/strong>, who lives with a group of females, is aggressive toward other males, who may try to take over the group and become the new resident male. Competition between males to be the resident male of a group is intense, and these species usually display sexual dimorphism, with males being larger than females and possessing large canines. Hanuman langurs (<em>Semnopithecus entellus<\/em>) of India form single-male, multi-female groups (Figure 7.12b). When a new male takes over a group of females and ousts the former resident male, he may commit <strong>[pb_glossary id=\"1060\"]infanticide[\/pb_glossary], <\/strong>or kill the unweaned infants. This is especially likely if the new resident male has not yet mated with any of the females and thus cannot be the infants\u2019 father. This causes the females, who were nursing, to become sexually receptive sooner, increasing the new resident male\u2019s chances of producing offspring (Sharma, Ram, and \u200b\u200bRaipurohit 2010). Gorillas, patas monkeys, and golden snub-nosed monkeys (<em>Rhinopithecus roxellana<\/em>) also live in single-male, multi-female groups.<\/p>\r\n&nbsp;\r\n\r\n<\/div>\r\n\r\n[caption id=\"attachment_210\" align=\"aligncenter\" width=\"749\"]<img class=\"wp-image-199\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/6.12.jpg\" alt=\"Left: Circle contains nine dots and one square; outside are three squares. Right: Adult langur and infant.\" width=\"749\" height=\"295\" \/> Figure 7.12a-b: An illustration of the one-male, multi-female grouping pattern is shown on the left. Key: square = adult male; dot = adult female; open circle represents the outline of the group\u2019s home range (or territory). The Hanuman langur (right) is an example of a species with a one-male, multi-female social system. Credit: a. Single-Male, Multi-Female Social System original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Karin Enstam Jaffe is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\"> CC BY-NC 4.0 License<\/a>. b. <a href=\"https:\/\/www.pexels.com\/photo\/close-up-photo-of-two-gray-langurs-8642891\/\">Close-up of Two Grey Langurs<\/a> by<a href=\"https:\/\/www.pexels.com\/@amitrai10\/\"> Amit Rai<\/a> has been modified (cropped) and is<a href=\"https:\/\/www.pexels.com\/license\/\"> free to use via Pexels<\/a>.[\/caption]\r\n\r\n<div class=\"__UNKNOWN__\">\r\n<h4 class=\"import-Normal\"><em>Multi-Male, Multi-Female<\/em><\/h4>\r\n<p class=\"import-Normal\"><strong>[pb_glossary id=\"1062\"]Multi-male, multi-female[\/pb_glossary]<\/strong> groups consist of multiple adult males living with multiple adult females and their dependent offspring. Although there is more than one adult male, there are more adult females than adult males in the group (Figure 7.13a). Multi-male, multi-female groups can range in size from about ten to as many as 500 individuals. They occupy a home range but may or may not defend a territory. In groups that contain multiple males and multiple females, it is not possible for one male to monopolize all the matings, so the mating system is <strong>[pb_glossary id=\"1064\"]polygamy[\/pb_glossary]<\/strong>, in which multiple males mate with multiple females. However, this does not mean that all males have an equal opportunity to mate with all females. In multi-male, multi-female groups, both males and females form a dominance hierarchy. The male dominance hierarchy determines their access to females for mating in much the same way that a female dominance hierarchy determines a female\u2019s access to food. Because their place in the hierarchy can affect their reproductive success, males compete with each other, but because it is rare for males to be excluded from mating altogether, the level of competition and degree of sexual dimorphism are less extreme than what we see in polygynous species. Usually, females are philopatric and males disperse. Vervet monkeys (Figure 7.13b), ring-tailed lemurs (<em>Lemur catta<\/em>), white-faced capuchins (<em>Cebus capucinus<\/em>), and black-capped squirrel monkeys (<em>Saimiri boliviensis<\/em>) live in multi-male, multi-female groups.<\/p>\r\n\r\n<\/div>\r\n&nbsp;\r\n\r\n[caption id=\"attachment_210\" align=\"aligncenter\" width=\"585\"]<img class=\"wp-image-200\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/6.13.jpg\" alt=\"Circle contains twelve dots and three squares. Right: Two vervet monkeys.\" width=\"585\" height=\"267\" \/> Figure 7.13a-b: An illustration of the multi-male, multi-female grouping pattern is shown on the left. Key: square = adult male; dot = adult female; open circle represents the outline of the group\u2019s home range (or territory). Vervet monkeys (right) are an example of a species that lives in multi-male, multi-female groups. Credit: a. Multi-Male, Multi-Female Social System original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Karin Enstam Jaffe is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\"> CC BY-NC 4.0 License<\/a>. b. <a href=\"https:\/\/www.flickr.com\/photos\/berniedup\/6011902081\/\">Vervet Monkeys (Chlorocebus pygerythrus)<\/a> by<a href=\"https:\/\/www.flickr.com\/people\/65695019@N07\"> Bernard DUPONT<\/a> has been modified (cropped) and is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/deed.en\"> CC BY-SA 2.0 License<\/a>.[\/caption]\r\n\r\n<div class=\"__UNKNOWN__\">\r\n<h4 class=\"import-Normal\"><em>Fission-Fusion<\/em><\/h4>\r\n<p class=\"import-Normal\"><strong>[pb_glossary id=\"1066\"]Fission-fusion[\/pb_glossary]<\/strong> is a fluid social system in which the size and composition of the social group changes, with groups splitting (fission) or merging (fusion) depending on food availability (Pinacho-Guendulain and Ramos-Fern\u00e1ndez 2017). When key resources are scarce, individuals spread out (fission) and move and feed individually or in small subgroups (Figure 7.14a). When key food resources are plentiful, individuals come together (fusion) and individuals travel and feed as a more cohesive group (Figure 7.14a). Fission-fusion social structure is believed to reduce feeding competition when resources are scarce. Because group composition changes over time, species with fission-fusion social systems are referred to as a community. Communities consist of multiple adult males, multiple adult females, and offspring, and group size varies but typically ranges from ten to a few dozen individuals. Females typically disperse and males are philopatric. Thus, community males are related and display unusual forms of cooperation. The mating system associated with fission-fusion is polygamy. Because males are not excluded from mating, competition for mates is relaxed and sexual dimorphism is moderate (males are slightly larger than females). Geoffroy\u2019s spider monkeys (<em>Ateles geoffroyi<\/em>) (Figure 7.14b) and chimpanzees both have fission-fusion social system.<\/p>\r\n\r\n<\/div>\r\n\r\n[caption id=\"attachment_210\" align=\"aligncenter\" width=\"720\"]<img class=\"wp-image-201\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/6.14.jpg\" alt=\"Diagrams show fission and fusion. Three spider monkeys.\" width=\"720\" height=\"289\" \/> Figure 7.14a-b: An illustration of the fission-fusion grouping pattern appears on the left. The left illustration represents fission, when females travel and feed independently in individual home ranges within the community boundary. The right illustration represents fusion, when community members form a cohesive group. <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>. Key: square = adult male; dot = adult female; open circle represents the outline of the community boundary. Open ovals represent individual female home ranges when the group fissions. Credits: a. Fission-Fusion Social System original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Karin Enstam Jaffe is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\"> CC BY-NC 4.0 License<\/a>. b. <a href=\"https:\/\/www.flickr.com\/photos\/berniedup\/49562895393\">Geoffry\u2019s Spider Monkeys (Ateles geoffroyi)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/65695019@N07\">Bernard DUPONT<\/a> has been modified (cropped) and is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/deed.en\"> CC BY-SA 2.0 License<\/a>.[\/caption]\r\n\r\n<div class=\"__UNKNOWN__\">\r\n<h4 class=\"import-Normal\"><em>Multi-Male, Single-Female<\/em><\/h4>\r\n<p class=\"import-Normal\">In <strong>[pb_glossary id=\"1068\"]multi-male, single-female[\/pb_glossary] <\/strong>groups, two or more males live with one breeding female, her dependent offspring, and non-breeding females (Figure 7.15a). This type of social system is found in the <strong>[pb_glossary id=\"1070\"]callitrichids[\/pb_glossary]<\/strong>, the primate family that includes marmosets (<em>Callithrix<\/em>; Figure 7.15b) and tamarins (<em>Saguinus<\/em>) of Central and South America. Their groups rarely exceed 15 individuals, and each group actively defends their territory from conspecifics. Although more than one adult female may live in the group, the mating system is <strong>[pb_glossary id=\"1072\"]polyandry[\/pb_glossary]<\/strong> because there is only one breeding female who mates with all of the adult males. This is achieved through <strong>[pb_glossary id=\"1074\"]reproductive suppression[\/pb_glossary]<\/strong>, which involves the breeding female preventing other females from reproducing through physiological and\/or behavioral means (Digby, Ferrari, and Salzman 2011). This limits the opportunities for other females in the group to become pregnant. Instead, these females, and the males in the group, help raise the breeding female\u2019s offspring. This is referred to as <strong>[pb_glossary id=\"1076\"]cooperative breeding[\/pb_glossary]<\/strong> and usually takes the form of carrying infants, grooming them, and protecting them from danger (de Oliveira Terceiro and Burkart 2019). Because reproductive opportunities for female tamarins and marmosets are limited, they are very competitive, and females are slightly larger than males, which helps them compete for the breeding spot in a group.<\/p>\r\n&nbsp;\r\n\r\n<\/div>\r\n\r\n[caption id=\"attachment_210\" align=\"aligncenter\" width=\"578\"]<img class=\"wp-image-202\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/6.15.jpg\" alt=\"Circle contains two squares, two unmarked dots, and a B dot. Right: Marmosets with twins.\" width=\"578\" height=\"269\" \/> Figure 7.15a-b: An illustration of multi-male, single-female grouping pattern appears on the left. Key: square = adult male; B dot = breeding female; unmarked dot = non-breeding female; open circle represents the outline of the group\u2019s territory, which is defended against conspecifics. The common marmoset (Callithrix jacchus) is an example of a primate species that has this type of social system (right). Credit: a. Multi-Male, Single-Female Social System original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Karin Enstam Jaffe is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\"> CC BY-NC 4.0 License<\/a>. b. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Family_of_Common_Marmoset_-_REGUA_-_Brazil_MG_9480_(12930855765).jpg\">Family of Common Marmoset - REGUA - Brazil MG 9480 (12930855765)<\/a> by<a href=\"https:\/\/www.flickr.com\/people\/30818542@N04\"> Francesco Veronesi<\/a> has been modified (cropped) and is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\"> CC BY-SA 2.0 License<\/a>.[\/caption]\r\n\r\n<div class=\"__UNKNOWN__\">\r\n<h2 class=\"import-Normal\">Reproductive Strategies<\/h2>\r\n<p class=\"import-Normal\">Reproductive strategies have evolved to maximize individual reproductive success. These strategies can be divided into those that deal with offspring production and care (parental investment) and those that maximize mating success (sexual selection). Because the reproductive physiology of male and female primates differs, males and females differ with regard to parental investment and sexual selection strategies. Female strategies focus on obtaining the food necessary to sustain a pregnancy and choosing the best male(s) to father offspring. Male strategies focus on gaining access to receptive females.<\/p>\r\n\r\n<h3 class=\"import-Normal\"><strong>Parental Investment<\/strong><\/h3>\r\n[caption id=\"\" align=\"alignright\" width=\"362\"]<img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image9.jpg\" alt=\"Monkey holds baby.\" width=\"362\" height=\"241\" \/> Figure 7.16: A female Japanese macaque nursing her infant. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Snow_monkey_baby_milk_time.jpg\">Snow monkey baby milk time<\/a> by Daisuke Tashiro is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\"> CC BY-SA 2.0 License<\/a>.[\/caption]\r\n\r\nBiologically speaking, <strong>[pb_glossary id=\"1078\"]parental investment[\/pb_glossary]<\/strong> is any time or energy a parent devotes to the current offspring that enhances its survival (and eventual reproductive success) at the expense of the parent\u2019s ability to invest in the next offspring (Trivers 1972). Female primates invest more heavily in offspring than males. Even before conception, females produce energy-containing eggs, and they will be responsible for sustaining a fertilized egg until it implants in the uterus. After that, they invest in pregnancy and lactation (Figure 7.16). Because all of this investment requires a lot of energy, female primates can only produce one offspring (or litter) at a time. A species\u2019 <strong>[pb_glossary id=\"1080\"]interbirth interval[\/pb_glossary]<\/strong>, or the typical length of time between one birth and the next, is determined by the length of time necessary to maximize each offspring\u2019s survival without jeopardizing the female\u2019s ability to produce the greatest number of offspring possible. If a female invests too little (i.e., weans an offspring too early), she may give birth to many offspring, but very few (if any) of them will survive. If she invests too much (i.e., nurses an offspring even after it could be weaned), she ensures the survival of that individual offspring but will not be able to produce very many during her lifetime. To maximize her reproductive success, a female must invest <em>just<\/em> long enough to ensure the greatest number of offspring survive to reproduce. We often think of maternal care as an <strong>[pb_glossary id=\"1082\"]innate[\/pb_glossary]<\/strong> (or natural), instinctive behavior. Yet this is not the case. The \u201cSpecial Topic: Is Maternal Behavior Innate?\u201d dispels the myth that maternal behavior is solely instinctual and explains how female primates learn to be good mothers.\r\n<h3 class=\"import-Normal\"><strong>Sexual Selection<\/strong><\/h3>\r\n<p class=\"import-Normal\"><strong>[pb_glossary id=\"1084\"]Sexual selection[\/pb_glossary]<\/strong>, or selection for traits that maximize mating success, comes in two forms. <strong>[pb_glossary id=\"1086\"]Intrasexual selection[\/pb_glossary]<\/strong> is selection for traits that enhance the ability of members of one sex to compete amongst themselves (\u201c<em>intra<\/em>sexual\u201d = within one sex). <strong>[pb_glossary id=\"1088\"]Intersexual selection[\/pb_glossary]<\/strong> is selection for traits that enhance the ability of one sex to attract the other (\u201c<em>inter<\/em>sexual\u201d = between the sexes).<\/p>\r\n<p class=\"import-Normal\">Intrasexual selection most often operates on males. In the wild, adult females are either pregnant or lactating for most of their adult lives. So, in a given population, there are usually more males available and willing to mate than there are females. The result? Females are a scarce resource over which males compete. Intrasexual selection favors traits that help a male win fights with other males. In primates, these traits include large body size (Figure 7.17a) and large canines (Figure 7.17b). Because females don\u2019t possess these same traits, males and females of some species look different; that is, they are sexually dimorphic (Figure 7.17a).<\/p>\r\n&nbsp;\r\n\r\n[caption id=\"attachment_207\" align=\"aligncenter\" width=\"691\"]<img class=\"wp-image-204\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/6.17.jpg\" alt=\"Male baboon with two females. Adult male baboon.\" width=\"691\" height=\"293\" \/> Figure 7.17a-b: a. Hamadryas baboons (Papio hamadryas) are sexually dimorphic. The male (left) is much bigger than the female (center) and also has different colored fur. b. Adult males, like this gelada baboon, also have larger canines than females. Credit: a. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Dierenpark_Emmen_baboon_(2679944324).jpg\">Dierenpark Emmen baboon (2679944324)<\/a> by<a href=\"https:\/\/www.flickr.com\/people\/80538772@N00\"> robin bos<\/a> has been modified (cropped) and is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/legalcode\"> CC BY 2.0 License.<\/a> b. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Olive_Baboon_Papio_anubis_in_Tanzania_3066_Nevit.jpg\">Olive Baboon Papio anubis, Picture Taken in Tanzania<\/a> by Nevit Dilmen has been modified (cropped) and is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/deed.en\">CC BY-SA 3.0 License<\/a>.[\/caption]\r\n<p class=\"import-Normal\">Intersexual selection also tends to operate on males, selecting traits that make a male more attractive to females. Females, in turn, choose among potential fathers. Because female primates invest more in offspring production and care than males (see the \u201cParental Investment\u201d section, above), it is more costly for them if the offspring dies before maturity or reaches maturity but does not reproduce. Thus, it benefits a female primate to be choosy and try to pick the healthiest male as a mate. Males must display traits that tell a female why she should choose <em>him<\/em>, and not another male, as her mate.<\/p>\r\n<p class=\"import-Normal\">What traits are female primates looking for? In humans, women may look for a mate who can provide important resources, such as food, paternal care, or protection. This is rare in other primates, though, since most females do not need males to provide resources. More commonly, female primates obtain genetic benefits for their offspring from choosing one male over another. Often the specific criteria by which females select mates is unknown. However, if a female chooses a healthy (as indicated by traits like a plush coat, bright coloration, or large body size) or older male, she may obtain genes for her offspring that code for health or long life. If a male\u2019s rank is determined by competitive ability that has a genetic component, females who choose males who win fights may acquire these genes (and qualities) for their offspring. Females in some species appear to prefer new immigrants, sometimes even \u201csneaking\u201d copulations with males who are not established members of their groups. Such a preference may provide their offspring with novel genes and increase genetic variation (for more about the importance of genetic variation, see Chapter 4). Female choice is often more subtle than male-male competition, so it can be more difficult to study. However, as more research is conducted, we continue to improve our understanding of the ways that female primates exert their choice.<\/p>\r\n\r\n<div class=\"textbox\">\r\n<h2 class=\"import-Normal\">Special Topic: Is Maternal Behavior Innate?<\/h2>\r\nZoos almost always have nurseries where infants are cared for by zookeepers if their mothers will not care for them (Figure 7.18). These exhibits are among the most popular because the babies are so cute and so much fun to watch. And the caretaking positions in zoo nurseries are often among the most coveted by zoo personnel for the same reasons. But if maternal behavior is instinctive, why do zoo nurseries even exist? The answer is that in many species, including primates, maternal behavior is not purely instinctual; it is dependent on <strong>[pb_glossary id=\"1090\"]social learning[\/pb_glossary]<\/strong> (behavior learned by observing and imitating others), as well.\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"433\"]<img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image13-1.png\" alt=\"Newborn orangutan feeding from a bottle.\" width=\"433\" height=\"336\" \/> Figure 7.18: Newborn orangutan at Audubon Zoo being bottle-fed. Credit: <a href=\"https:\/\/newsroom.audubonnatureinstitute.org\/critically-endangered-orangutan-gives-birth-at-audubon-zoo\/\">Newborn orangutan born at Audubon Zoo being bottle fed<\/a> (2022) by<a href=\"https:\/\/audubonnatureinstitute.org\/\"> Audubon Nature Institute<\/a> is used by permission.[\/caption]\r\n\r\nCaptive female primates, including gorillas and chimpanzees, who have not had the opportunity to observe their mother or other females care for infants do not know how to care for their own offspring. Although it is preferred that the primate mother care for her own infant, there are cases when she will not and humans must step in to ensure the offspring survives. When hand-rearing by humans is necessary, the infant is returned to the group as soon as possible in the hopes that it will learn species-typical behavior from its mother and other conspecifics. Observations such as these indicate that maternal behavior is learned, not innate, and that maternal care is critically important to the social and psychological development of young primates.\r\n\r\n<\/div>\r\n<h2 class=\"import-Normal\">Communication<\/h2>\r\n<p class=\"import-Normal\">In its most basic form, communication occurs when one individual (the sender) emits a signal that conveys information, which is detected by another individual (the receiver). We have discussed several aspects of primate sociality in this chapter, all of which require the communication of information between individuals. But exactly <em>how<\/em> does a female chimpanzee communicate her sexual availability? <em>How<\/em> does a vervet monkey communicate the approach of a leopard or that a python is nearby? <em>How<\/em> do solitary, nocturnal primates, like the slow loris, communicate information about themselves to conspecifics? Primate communication comes in four forms: vocal, visual, olfactory, and tactile. Species vary in their reliance on each.<\/p>\r\n\r\n<h3 class=\"import-Normal\"><strong>Vocal Communication<\/strong><\/h3>\r\n<p class=\"import-Normal\">Primates use sound to communicate danger or threats, to claim and maintain a territory, or make contact with other group members. Alarm calls are given in response to predators. In some cases, alarm calls are used to alert members of the group to the presence of a predator so they can take evasive action. In other cases, they are directed at the predator itself, signaling that it has been detected. You can learn more about alarm calls as forms of vocal communication in the highlight box in this chapter entitled \u201cDig Deeper: Alarm Calls: Signals to Friends or Foes?.\u201d<\/p>\r\n<p class=\"import-Normal\">Loud calls are designed to travel great distances and are used in territorial defense by many primate species including indris (<em>Indri indri<\/em>), orangutans, gibbons, and howler monkeys (<em>Alouatta<\/em>). In dense forest, where visual communication can be difficult, loud calls can be useful in signaling to conspecifics that a group or individual occupies a specific area. Howler monkeys are named for their loud calls, or \u201croars,\u201d which can be heard one kilometer or more away (Sch\u00f6n Ybarra 1986). Howler monkey roars may act to maintain distance between neighboring groups or keep extragroup males from entering the home range (Sch\u00f6n Ybarra 1986).<\/p>\r\n<p class=\"import-Normal\">Other vocalizations are intended to communicate with individuals in one\u2019s own group. These include vocalizations given as part of threat displays or dominance interactions, as well as contact calls that provide information about one\u2019s location to other group members. Chacma baboons (<em>Papio ursinus<\/em>) have a rich repertoire of vocalizations for communicating with other group members (Fischer et al. 2008). Adult males give specific vocalizations during threat displays and physical confrontations. Subordinates \u201cscreech\u201d when retreating from a dominant individual, signaling submission. Since baboons rely on membership in their group for finding food and detecting predators, a baboon separated from his group will vocalize in an attempt to regain contact. Young baboons emit their own contact calls when separated from their mothers.<\/p>\r\n\r\n<h3 class=\"import-Normal\"><strong>Visual Communication<\/strong><\/h3>\r\n[caption id=\"attachment_207\" align=\"alignleft\" width=\"493\"]<img class=\"wp-image-206\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/6.19.jpg\" alt=\"Female baboon with sexual swelling.\u00a0Male and female baboon.\" width=\"493\" height=\"209\" \/> Figure 7.19a-b: Two female hamadryas baboons. The female on the left has a sexual swelling while the female on the right (in foreground, with infant clinging to her belly) does not. An adult male is behind her. Credit: a. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Sexual_swelling_in_female_Hamadryas_baboon.jpg\">Sexual swelling in female Hamadryas baboon<\/a> by<a href=\"https:\/\/www.flickr.com\/photos\/mamoritai\/\"> Mamoritai<\/a> has been modified (cropped) and is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\"> CC BY-SA 2.0 License<\/a>. b. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Hamadryas_baboon_at_Giza_Zoo_by_Hatem_Moushir_36.JPG\">Hamadryas baboon at Giza Zoo by Hatem Moushir 36<\/a> by<a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Hatem_Moushir\"> Hatem Moushir<\/a> has been modified (cropped) and is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\"> CC BY-SA 3.0 License<\/a>.[\/caption]\r\n\r\n<strong>[pb_glossary id=\"1092\"]Visual communication[\/pb_glossary]<\/strong>, which involves signals that can be seen, is an important component of nonhuman primate behavior, alone or in combination with other forms of communication. <strong>[pb_glossary id=\"1094\"]Piloerection[\/pb_glossary]<\/strong>, or raising one\u2019s hair or fur, is used in aggressive interactions to make an individual appear larger than it actually is. Female macaques (<em>Macaca<\/em>), baboons (<em>Papio<\/em>), and chimpanzees, signal sexual receptivity through changes in the size, shape, and, often, color of their hindquarters, called a <strong>[pb_glossary id=\"1096\"]sexual swelling[\/pb_glossary]<\/strong> (Figure 7.19a). The sexual swelling reaches its maximum size at ovulation. When females are not receptive, either because they are pregnant or are nursing, they do not display a sexual swelling (Figure 7.19b). Thus, the presence or absence of a sexual swelling signals a female\u2019s reproductive state.\r\n\r\nMonkeys and apes use diverse facial expressions in visual communication. Showing your teeth in a \u201csmile\u201d sends a signal of friendship in humans. Displaying teeth in this way is a sign of anxiety or fear in primates. That male mandrill you see \u201cyawning\u201d at your local zoo is actually displaying his teeth to signal tension or to threaten a rival (Figure 7.20a). In addition to showing their canines, male gelada baboons use \u201clip flips,\u201d in which the gums and teeth are exposed by flipping the upper lip up over the nostrils (Figure 7.20b), and \u201craised eyelids,\u201d in which the pale eyelids are exposed by pulling the scalp back as threatening gestures (Aich, Moos-Heilen, and Zimmerman 1990). Submissive males respond by fleeing or presenting their hindquarters.\r\n\r\n[caption id=\"attachment_207\" align=\"aligncenter\" width=\"597\"]<img class=\"wp-image-207\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/6.20-1.jpg\" alt=\"Adult male mandrill and adult male hamadryas baboon yawning.\" width=\"597\" height=\"310\" \/> Figure 7.20a-b: Males use visual displays to communicate with other males. The male mandrill (left) is yawning to display his canines, and the male gelada baboon (right) enhances the yawn by flipping his upper lip back and raising his eyelids. Credit: a. <a href=\"https:\/\/pxhere.com\/en\/photo\/559944\">Mandrill<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/mathiasappel\/with\/24639723420\/\">Mathias Appel<\/a> has been modified (cropped) and designated to the <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/cc0\/\">public domain (CC0)<\/a>. b.<a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:BabouinGeladaAuReveil.JPG\"> BabouinGeladaAuReveil<\/a> by<a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:BluesyPete\"> BluesyPete<\/a> has been modified (cropped) and is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\"> CC BY-SA 3.0 License<\/a>.[\/caption]\r\n\r\n<\/div>\r\n<div class=\"__UNKNOWN__\">\r\n\r\n[caption id=\"attachment_209\" align=\"alignleft\" width=\"414\"]<img class=\"wp-image-208\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/6.22.jpg\" alt=\"A bald uakari. A spider monkey.\" width=\"414\" height=\"154\" \/> Figure 7.22a-b: Many monkey species have colorful faces, including the bald uakari (Cacajao calvus; left) and the white-bellied spider monkey (Ateles belzebuth) (right). Credit: a. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Uakari.jpg\">Uakari<\/a> by Coada dragos has been modified (cropped) and is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\"> CC BY-SA 4.0 License<\/a>. 6.22b <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Ateles_belzebuth_(White-bellied_spider_monkey)_2.jpg\">Ateles belzebuth (White-bellied spider monkey) 2<\/a> by<a href=\"https:\/\/www.flickr.com\/photos\/ewas-world\/\"> Ewa<\/a> (username: Ewcek65) has been modified (cropped) and is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/legalcode\"> CC BY 2.0 License<\/a>.[\/caption]\r\n\r\n[caption id=\"\" align=\"alignright\" width=\"163\"]<img class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image4-3.png\" alt=\"A male mandrill\u2019s face.\" width=\"163\" height=\"246\" \/> Figure 7.21: The colorful face of the male mandrill provides information about health and fitness to other mandrills.Credit: <a href=\"https:\/\/www.flickr.com\/photos\/mathiasappel\/24842082402\/\">Mandrill<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/mathiasappel\/with\/24639723420\/\">Mathias Appel<\/a> has been modified (cropped) and designated to the <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/cc0\/\">public domain (CC0)<\/a>.[\/caption]\r\n\r\nPrimates also communicate through color. In female and male mandrills, facial coloration provides information about an individual\u2019s health, competitive ability, and reproductive state to conspecifics (Figure 7.21; Setchell et al. 2008; Setchell, Wickings, and Knapp 2006). Variation in facial coloration among monkeys of Central and South America ranges from very simple (Figure 7.22a) to complex (Figure 7.22b). Species living with larger numbers of other primate species have evolved more complex facial coloration patterns, suggesting that this trait evolved as a form of <strong>[pb_glossary id=\"1098\"]species recognition[\/pb_glossary]<\/strong>, or the ability to differentiate conspecifics from members of other species (Santana, Lynch Alfaro, and Alfaro 2012).\r\n<h3 class=\"import-Normal\"><strong>Olfactory Communication<\/strong><\/h3>\r\n<p class=\"import-Normal\">All primates use scent to communicate. Females secrete chemicals from their <strong>[pb_glossary id=\"1100\"]anogenital[\/pb_glossary] <\/strong>region (the area of the anus and genitals) that provide males with information about their reproductive state. In some species, like macaques and chimpanzees, this olfactory signal is enhanced by a sexual swelling, as discussed above. <strong>[pb_glossary id=\"1102\"]Olfactory communication[\/pb_glossary]<\/strong>, or communicating through scent, is particularly important for monkeys of Central and South America, lemurs, and lorises. Male and female common squirrel monkeys (<em>Saimiri sciureus<\/em>) (Figure 7.23a) engage in \u201curine washing,\u201d in which an individual urinates on its hands and feet and then uses them to spread urine all over its body. Urine washing may be used to mark trails for others to follow, to control body temperature, as part of dominance displays, or to communicate reproductive state (Boinski 1992). During aggressive interactions with other males, male ring-tailed lemurs rub their tails with scent from glands on their wrists and chests. They use their \u201cperfumed\u201d tails in aggressive interactions with other males, who may respond by waiving their own scented tail, with physical aggression, or by fleeing (Jolly 1966). Males also waive their tails, saturated in scent, to attract females (Shirasu et al. 2020). Males use scent glands in their wrists to mark territorial boundaries (Figure 7.23b; Mertl-Millhollen 1988).<\/p>\r\n\r\n<\/div>\r\n&nbsp;\r\n\r\n[caption id=\"attachment_210\" align=\"aligncenter\" width=\"641\"]<img class=\"wp-image-210\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/6.23.jpg\" alt=\"A squirrel monkey. A ring-tailed lemur.\" width=\"641\" height=\"332\" \/> Figure 7.23a-b: Some primates, like the common squirrel monkey (left) and the ring-tailed lemur (right), communicate using scent. Credit: a. <a href=\"https:\/\/www.flickr.com\/photos\/rubund\/6337874822\/\">Saimiri sciureus<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/rubund\/\">Ruben Undheim<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/\">CC BY-SA 2.0 License<\/a>. b. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Lemur_catta_004.jpg\">Lemur catta 004<\/a> by <a href=\"https:\/\/en.wikipedia.org\/wiki\/User:Maky\">Maky<\/a> has been modified (cropped) and is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/deed.en\">CC BY-SA 3.0 License<\/a>.[\/caption]\r\n\r\n<div class=\"__UNKNOWN__\">\r\n<h3 class=\"import-Normal\"><strong>Tactile Communication<\/strong><\/h3>\r\n<p class=\"import-Normal\"><strong>[pb_glossary id=\"1104\"]Tactile communication[\/pb_glossary]<\/strong>, or communicating through touch, is very important in all primate species. Physical contact is used to comfort and reassure, is part of courtship and mating, and is used to establish dominance and alliances. Grooming is an important and clearly enjoyable form of tactile communication for all primates (Figure 7.24). Not only does grooming serve to clean the skin and fur, removing parasites and debris, but it is an important affiliative behavior that helps reinforce social bonds, repair relationships, and cement alliances.<\/p>\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"674\"]<img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image1-8.png\" alt=\"Four primate species grooming.\" width=\"674\" height=\"478\" \/> Figure 7.24: Examples of grooming in Japanese macaques (upper left), tufted capuchins (Sapajus apella) (upper right), gelada baboons (lower left), and black-and-white ruffed lemurs (Varecia variegata; lower right). Credit: Examples of grooming original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Karin Jaffe 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:Yakushima_macaques_grooming_each_other.jpg\">Yakushima macaques grooming each other<\/a> by<a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Grendelkhan\"> Grendelkhan<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\">CC BY-SA 4.0 License<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Tufted_capuchin_monkeys_grooming_session_III.jpg\">Tufted capuchin monkeys grooming session III<\/a> by Adrian Soldati, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\">CC BY-SA 4.0 License<\/a>;<a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Baboons_Wunania_012018.jpg\"> Baboons Wunania 012018<\/a> by Kim Toogood, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\">CC BY-SA 4.0 License<\/a>;<a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Black-and-white_ruffed_lemur_03.jpg\"> Black-and-white ruffed lemur 03<\/a> by Mattis2412, <a href=\"https:\/\/creativecommons.org\/publicdomain\/zero\/1.0\/deed.en\">public domain (CC0 1.0)<\/a>].[\/caption]\r\n<div class=\"textbox shaded\">\r\n<h2 class=\"import-Normal\">Dig Deeper: Alarm Calls: Signals to Friends or Foes?<\/h2>\r\n<p class=\"import-Normal\">Alarm calls are common among group-living primates. They often serve to notify conspecifics of potential danger, as is the case with vervet monkeys. Research has shown that: (1) vervets classify predators based on hunting style; (2) alarm calls convey information to other vervets about that hunting style; and (3) other vervets respond in ways appropriate for evading that type of predator (Seyfarth, Cheney, and Marler 1980a). When a vervet gives a \u201cleopard\u201d alarm call (directed at mammalian carnivores like leopards, Figure 7.25a), monkeys on the ground climb the nearest tree, while monkeys already in trees stay there or climb higher. Since most mammalian carnivores hunt on the ground, getting into, and staying in, a tree is the best option for escape. When the \u201csnake\u201d alarm call is given, vervets stand on their hind legs and look down at the ground (Figure 7.25b). Since snakes are not pursuit predators, locating them quickly so as to avoid them is the best strategy. Lastly, when an \u201ceagle\u201d alarm call is given, vervets look up or run into bushes, both of which are useful responses for avoiding hawks and eagles, which attack from above (Figure 7.25c). Vervets clearly understand the meaning of each type of alarm call, as they respond appropriately even when they do not see the actual predator (Seyfarth, Cheney, and Marler 1980b). Such <strong>[pb_glossary id=\"1106\"]semantic communication[\/pb_glossary]<\/strong>, which involves the systematic use of signals to refer to objects in the environment, was once believed to be unique to humans. It may be a precursor to the symbolic capacities of human language.<\/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\/image5-1.jpg\" alt=\"Primate in a tree views a leopard.\" width=\"482\" height=\"344\" \/> Figure 7.25a[\/caption]\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"484\"]<img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image2-2.jpg\" alt=\"Primate views snake on the ground.\" width=\"484\" height=\"338\" \/> Figure 7.25b[\/caption]\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"481\"]<img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image4-2.jpg\" alt=\"Primate on the ground sees bird.\" width=\"481\" height=\"517\" \/> Figure 7.25c\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 Figure 7.25a-c: Vervet monkeys respond in different ways to alarm calls for each of their three main predators (leopards, snakes, and eagles) which are appropriate to predator hunting strategies. Credit: Vervet Monkey Alarm Calls by Mary Nelson, original to Explorations: An Open Invitation to Biological Anthropology, 2nd edition, is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.[\/caption]\r\n<p class=\"import-Normal\">Research on other African monkeys indicates that some species use alarm calls to signal to the predator that it has been detected. Diana monkeys (<em>Cercopithecus diana<\/em>) give alarm calls to leopards (<em>Panthera pardus<\/em>) but not chimpanzees (Zuberb\u00fchler, No\u00eb, and Seyfarth 1997). Because leopards are stealth predators, they rely on the element of surprise to sneak up on their prey (Figure 7.26a). Alarm calling at leopards appears to tell the leopard that it has been seen and therefore its chance of success will be low. Research shows leopards are more likely to stop hunting after an alarm call has been emitted. Unlike leopards, chimpanzees are pursuit predators and may even use alarm calls to locate potential prey (Figure 7.26b). With such a predator, prey are better off remaining as silent as possible so as not to alert the predator to their location (Zuberb\u00fchler et al. 1999).<\/p>\r\n\r\n\r\n[caption id=\"attachment_215\" align=\"alignnone\" width=\"1907\"]<img class=\"wp-image-215 size-full\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/6.26.jpg\" alt=\"Leopard crouches in grass. Chimpanzee looks up. \" width=\"1907\" height=\"589\" \/> Figure 7.26a-b: Because leopards (left) and chimpanzees (right) hunt differently, Diana monkeys react differently to them. Credit: a. <a href=\"https:\/\/www.flickr.com\/photos\/thimindu\/5842997328\">Crouching Leopard<\/a> by<a href=\"https:\/\/www.flickr.com\/photos\/thimindu\/\"> Thimindu Goonatillake<\/a> is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/\"> CC BY-SA 2.0 License<\/a>. b. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Chimpanzee_in_the_wild.jpg\">Chimpanzee in the wild<\/a> by D.G. Kulakov is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/deed.en\"> CC BY-SA 4.0 License<\/a>.[\/caption]\r\n<p class=\"import-Normal\"><\/p>\r\n\r\n<\/div>\r\n<h2 class=\"import-Normal\"><span style=\"text-align: initial;font-size: 1em\">The Question of Culture<\/span><\/h2>\r\n<p class=\"import-Normal\">It may be surprising in a chapter on nonhuman primates to see a discussion of culture. After all, culture is considered by many, including cultural anthropologists, to be a distinguishing characteristic of humans. Indeed, some anthropologists question claims of culture in primates and other animals. Definitions of animal culture focus on specific behaviors that are unique to one population. Anthropological definitions of human culture emphasize shared ideology (e.g., values, morals, beliefs) and symbols, not just behavior. Using this definition, some cultural anthropologists view primates as lacking culture because of the absence of symbolic life (e.g., religion). However, the longer we study primate groups and populations, the more insight we gain into primate behavioral variation. If we define <strong>[pb_glossary id=\"1108\"]culture[\/pb_glossary]<\/strong> as the transmission of behavior from one generation to the next through social learning, then we must view at least some of the behavioral variation we see in primates as forms of <strong>[pb_glossary id=\"1110\"]cultural tradition[\/pb_glossary]<\/strong>, or a distinctive pattern of behavior shared by multiple individuals in a social group that persists over time (Whiten 2001).<\/p>\r\n\r\n<h3 class=\"import-Normal\"><strong>Chimpanzee Culture<\/strong><\/h3>\r\n<p class=\"import-Normal\">Due to both their high level of intelligence and the large number of long-term studies on several different populations, chimpanzees provide the best example of cultural tradition in primates. Chimpanzees express cultural variation in multiple behavioral patterns, ranging from population-specific prey preferences and hunting strategies to tool-use techniques and social behaviors. For example, in Tanzania, chimpanzees fish for termites by stripping twigs and then poking the twigs into termite mounds. The termites react to the \u201cinvasion\u201d by attacking the twig. The chimpanzee pulls the twig out, termites attached, and eats them. In Gambia, they use modified twigs to extract honey from holes in trees. In Fongoli, S\u00e9n\u00e9gal, chimpanzees use sticks as \u201cspears\u201d that they stab into tree cavities to hunt for galagos (Figure 7.27). Multiple chimpanzee populations use a \u201chammer and anvil\u201d to crack open nuts, but the specific techniques differ. Because the cultural traditions are so diverse and unique, if a researcher can observe enough of a chimpanzee\u2019s behavior, it is possible to assign that individual to a specific community, much in the same way a human being can be associated with a specific culture based on his or her behavior (Whiten 2011).<\/p>\r\n\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"800\"]<img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image3-4.jpg\" alt=\"Chimpanzees hunting galagos by poking them with a stick. \" width=\"800\" height=\"453\" \/> Figure 7.27a-d: Tool-assisted hunting by a chimpanzee at Fongoli, S\u00e9n\u00e9gal. An adult male chimpanzee uses a tree branch with a modified end to (a\u2013c) stab into a cavity within a hollow tree branch that houses a galago. He ultimately captures the galago as (d) his adolescent brother looks on. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Pan_troglodytes,_tool_use_in_Senegal.jpg\">Pan troglodytes, tool use in Senegal<\/a> by<a href=\"https:\/\/royalsocietypublishing.org\/content\/2\/4\/140507\"> J. D. Pruetz, P. Bertolani, K. Boyer Ontl, S. Lindshield, M. Shelley, and E. G. Wessling<\/a> is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/legalcode\"> CC BY 4.0 License<\/a>.[\/caption]\r\n<p class=\"import-Normal\">How do chimpanzee cultures develop, and how does cultural transmission occur? Although we do not know for sure how chimpanzee cultural traditions develop initially, it is possible that different groups invent, either accidentally or deliberately, certain behaviors that other individuals copy. <strong>[pb_glossary id=\"1112\"]Immigration[\/pb_glossary]<\/strong>, or movement of an individual into a new group or community, is an important avenue of cultural transmission in chimpanzees, much as it is between human cultures. Immigrants (typically females) may bring cultural traditions to their new community, which residents observe and learn. Conversely, immigrants may observe and learn a cultural tradition practiced in their new community (Whiten 2011).<\/p>\r\n\r\n<h3 class=\"import-Normal\"><strong>Cultural Transmission in Macaques<\/strong><\/h3>\r\n<p class=\"import-Normal\">Two monkey species are well-known for behavioral variation that has been called \u201cpre-cultural\u201d by some primatologists: Japanese macaques and tufted capuchins (<em>Sapajus apella<\/em>). The transmission of unique <strong>[pb_glossary id=\"1114\"]foraging[\/pb_glossary]<\/strong> (the act of searching for food) behaviors through the members of a provisioned group of Japanese macaques on Koshima Island is well known (Matsuzawa 2015). In an effort to keep the monkeys nearby, researchers provided them with piles of sweet potatoes. A juvenile female named Imo spontaneously washed a muddy sweet potato in a stream. This new food-processing technique first spread among other juveniles and then gradually to older individuals. Within 30 years, it had spread across generations, and 46 of 57 monkeys in the group engaged in the behavior. Another example comes from a group living far to the north, in Shiga-Heights, Nagano Prefecture. Researchers used apples to entice Japanese macaques to the area. Within a few years, monkeys visited the area regularly and were observed playing with the water in the hot springs. Soon, they climbed into the hot springs and learned to immerse themselves to keep warm and reduce stress when not foraging (Figure 7.28; Matsuzawa 2018; Takeshita et al. 2018; recall also our discussion of hot spring use as an example of analogous traits at the beginning of this chapter). These examples share several characteristics with human culture, including invention or modification of behavior, transmission of behavior between individuals, and the persistence of the behavior across generations (McGrew 1998).<\/p>\r\n\r\n\r\n[caption id=\"\" align=\"alignleft\" width=\"477\"]<img src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image6-4.png\" alt=\"Two monkeys in a hot spring.\" width=\"477\" height=\"292\" \/> Figure 7.28: Hot spring use by Japanese macaques is a culturally transmitted behavior. Credit: <a href=\"https:\/\/www.flickr.com\/photos\/peterthoeny\/32160301021\">Oooh, This Feels Sooo Good!<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/peterthoeny\/\">Peter Theony - Quality HD Photography<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\">CC BY-NC-SA 2.0 License<\/a>.[\/caption]\r\n<h2 class=\"import-Normal\">Summary<\/h2>\r\n<p class=\"import-Normal\">Primates are socially complex, extremely intelligent, and highly adaptable. In this chapter we discussed aspects of primate ecology, including how body size and characteristics of food affect what primates eat and how primates interact with other species in their environment. We examined why primates live in groups, the types of groups in which they are found, and the reproductive strategies used by males and females to maximize reproductive success. Like other aspects of their behavior, primate communication is varied and complex, and we discussed how primates communicate using vocal, visual, olfactory, and tactile signals. Finally, we explored the question of culture among nonhuman primates and learned that some species have cultural traditions, distinctive patterns of behavior shared by multiple individuals in a social group that persist over time. Humans and other primates are similar in many ways. Learning about principles of primate ecology and behavior can help us better understand our own behavior and the behaviors of our extinct relatives.<\/p>\r\n\r\n<div class=\"textbox shaded\">\r\n<h2 class=\"import-Normal\">Review Questions<\/h2>\r\n<ul>\r\n \t<li class=\"import-Normal\">If anthropology is the study of humans, why do some anthropologists study primates?<\/li>\r\n \t<li class=\"import-Normal\">How does a primate\u2019s ecology affect their diet and interactions with other organisms?<\/li>\r\n \t<li class=\"import-Normal\">Why do primates live in groups and in what types of groups do they live?<\/li>\r\n \t<li class=\"import-Normal\">What is parental investment and sexual selection?<\/li>\r\n \t<li class=\"import-Normal\">What are some examples of primate communication?<\/li>\r\n \t<li class=\"import-Normal\">What is the evidence for cultural traditions in primates and how do primatologists think cultural transmission occurs in primates?<\/li>\r\n<\/ul>\r\n<\/div>\r\n<h2 class=\"import-Normal\">Key Terms<\/h2>\r\n<p class=\"import-Normal\"><strong>Abundance<\/strong>: How much food is available in a given area.<\/p>\r\n<p class=\"import-Normal\"><strong>Adaptation<\/strong>: A trait with a function.<\/p>\r\n<p class=\"import-Normal\"><strong>Affiliative<\/strong>: Nonaggressive social interactions and associations between individuals.<\/p>\r\n<p class=\"import-Normal\"><strong>Agonistic<\/strong>: Conflict; aggressive interactions between individuals.<\/p>\r\n<p class=\"import-Normal\"><strong>Alarm calling<\/strong>: Vocalizations emitted by social animals in response to danger.<\/p>\r\n<p class=\"import-Normal\"><strong>Analogy<\/strong>: A similar trait found in different species that arose independently.<\/p>\r\n<p class=\"import-Normal\"><strong>Anogenital<\/strong>: Relating to the anus and genitals.<\/p>\r\n<p class=\"import-Normal\"><strong>Breeding season<\/strong>: The time of year when females are receptive to mating.<\/p>\r\n<p class=\"import-Normal\"><strong>Callitrichids<\/strong>: The primate family that includes marmosets and tamarins.<\/p>\r\n<p class=\"import-Normal\"><strong>Carnivores<\/strong>: Organisms whose diet consists primarily of animal tissue.<\/p>\r\n<p class=\"import-Normal\"><strong>Coalition<\/strong>: A temporary alliance between individuals.<\/p>\r\n<p class=\"import-Normal\"><strong>Community ecology<\/strong>: The branch of ecology that deals with the relationships and interactions between different organisms that occupy the same habitat.<\/p>\r\n<p class=\"import-Normal\"><strong>Comparison<\/strong>: An examination of the similarities and differences between two things, such as two primate species.<\/p>\r\n<p class=\"import-Normal\"><strong>Conspecifics<\/strong>: Members of the same species.<\/p>\r\n<p class=\"import-Normal\"><strong>Cooperative breeding<\/strong>: When individuals other than the mother and father help raise the offspring.<\/p>\r\n<p class=\"import-Normal\"><strong>Crypsis<\/strong>: The ability to avoid detection by other organisms, such as predators.<\/p>\r\n<p class=\"import-Normal\"><strong>Cultural tradition<\/strong>: A distinctive pattern of behavior shared by multiple individuals in a social group, which persists over time and is acquired through social learning.<\/p>\r\n<p class=\"import-Normal\"><strong>Culture<\/strong>: The transmission of behavior from one generation to the next through observation and imitation.<\/p>\r\n<p class=\"import-Normal\"><strong>Decolonize<\/strong>: Understanding and highlighting the theory and research of non-Western individuals and perspectives.<\/p>\r\n<p class=\"import-Normal\"><strong>Descendant<\/strong>: A species that comes after the ancestor species.<\/p>\r\n<p class=\"import-Normal\"><strong>Direct competition:<\/strong> Competition that involves physical interaction between individuals, such as fighting.<\/p>\r\n<p class=\"import-Normal\"><strong>Dispersal<\/strong>: To leave one\u2019s group or area. This may or may not involve joining another group.<\/p>\r\n<p class=\"import-Normal\"><strong>Distribution<\/strong>: How food is spread out.<\/p>\r\n<p class=\"import-Normal\"><strong>Diurnal<\/strong>: Active during the day.<\/p>\r\n<p class=\"import-Normal\"><strong>Dominance hierarchy<\/strong>: The ranked organization of individuals established by the outcome of aggressive-submissive interactions.<\/p>\r\n<p class=\"import-Normal\"><strong>Dominant<\/strong>: Being of high rank.<\/p>\r\n<p class=\"import-Normal\"><strong>Ecology<\/strong>: The relationship between organisms and their physical surroundings.<\/p>\r\n<p class=\"import-Normal\"><strong>Ecotourism<\/strong>: A form of tourism that focuses on nature-based attractions to provide learning opportunities and that uses economically and ecologically sustainable practices.<\/p>\r\n<p class=\"import-Normal\"><strong>Ethology<\/strong>: The study of animal behavior.<\/p>\r\n<p class=\"import-Normal\"><strong>Fission-fusion<\/strong>: Societies in which group composition is flexible, such as chimpanzee and spider monkey societies. Individuals may break up into smaller feeding groups (fission) and combine into larger groups (fusion).<\/p>\r\n<p class=\"import-Normal\"><strong>Fitness<\/strong>: An individual\u2019s ability to survive and reproduce relative to other members of the same species.<\/p>\r\n<p class=\"import-Normal\"><strong>Folivores<\/strong>: Organisms whose diet consists primarily of leaves.<\/p>\r\n<p class=\"import-Normal\"><strong>Foraging<\/strong>: The act of searching for food.<\/p>\r\n<p class=\"import-Normal\"><strong>Frugivores<\/strong>: Organisms whose diet consists primarily of fruit.<\/p>\r\n<p class=\"import-Normal\"><strong>Grooming<\/strong>: Picking through the fur of another individual for cleaning or bonding purposes.<\/p>\r\n<p class=\"import-Normal\"><strong>Heterospecifics<\/strong>: Members of different species.<\/p>\r\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>\r\n<p class=\"import-Normal\"><strong>Home range<\/strong>: The area that a group or individual uses over a given period of time (often over a year).<\/p>\r\n<p class=\"import-Normal\"><strong>Homology<\/strong>: A similar trait found in different species because it was inherited from a common ancestor.<\/p>\r\n<p class=\"import-Normal\"><strong>Immigration<\/strong>: Movement of an individual into a new group or community.<\/p>\r\n<p class=\"import-Normal\"><strong>Indirect competition<\/strong>: Competition that does not involve physical interaction between individuals, such as eating food before another individual arrives at the food site.<\/p>\r\n<p class=\"import-Normal\"><strong>Infanticide<\/strong>: The killing of infants of one\u2019s own species.<\/p>\r\n<p class=\"import-Normal\"><strong>Innate<\/strong>: Natural; as in behavior that comes naturally.<\/p>\r\n<p class=\"import-Normal\"><strong>Insectivores<\/strong>: Organisms whose diets consist primarily of insects.<\/p>\r\n<p class=\"import-Normal\"><strong>Interbirth interval<\/strong>: The typical length of time between one birth and the next for a species.<\/p>\r\n<p class=\"import-Normal\"><strong>Intersexual selection<\/strong>: The selection for traits that enhance the ability of the members of one sex to attract the attention of the other.<\/p>\r\n<p class=\"import-Normal\"><strong>Intrasexual selection<\/strong>: Selection for traits that enhance the ability of members of one sex to compete amongst themselves.<\/p>\r\n<p class=\"import-Normal\"><strong>Mating system<\/strong>: A way of describing which male(s) and female(s) mate.<\/p>\r\n<p class=\"import-Normal\"><strong>Metabolism<\/strong>: The chemical changes that take place in an organism that turn nutrients into energy.<\/p>\r\n<p class=\"import-Normal\"><strong>Mobbing<\/strong>: Cooperatively attacking or harassing a predator.<\/p>\r\n<p class=\"import-Normal\"><strong>Monogamy<\/strong>: A mating system in which one male mates with one female.<\/p>\r\n<p class=\"import-Normal\"><strong>Multi-male, multi-female<\/strong>: A group that consists of multiple adult males, multiple adult females, and their dependent offspring.<\/p>\r\n<p class=\"import-Normal\"><strong>Multi-male, single-female<\/strong>: A group that consists of two or more adult males, one breeding female, their dependent offspring, and non-breeding females.<\/p>\r\n<p class=\"import-Normal\"><strong>Mutualistic\/mutualism<\/strong>: When different species work together, with each benefiting from the interaction.<\/p>\r\n<p class=\"import-Normal\"><strong>Niche<\/strong>: The role of a species in its environment; how it meets its needs for food, shelter, etc.<\/p>\r\n<p class=\"import-Normal\"><strong>Nocturnal<\/strong>: Active at night.<\/p>\r\n<p class=\"import-Normal\"><strong>Olfactory communication<\/strong>: Conveying information through scent.<\/p>\r\n<p class=\"import-Normal\"><strong>Omnivores<\/strong>: Organisms whose diet consists of plant and animal matter.<\/p>\r\n<p class=\"import-Normal\"><strong>Pair bond<\/strong>: A strong, long-term relationship between two individuals.<\/p>\r\n<p class=\"import-Normal\"><strong>Parasite<\/strong>: An organism that lives in or on another organism.<\/p>\r\n<p class=\"import-Normal\"><strong>Parental investment<\/strong>: Any time or energy a parent devotes to the current offspring that enhances its survival (and eventual reproductive success) at the expense of the parent\u2019s ability to invest in the next offspring.<\/p>\r\n<p class=\"import-Normal\"><strong>Philopatric<\/strong>: Remaining in the group of one\u2019s birth.<\/p>\r\n<p class=\"import-Normal\"><strong>Piloerection<\/strong>: Raising one\u2019s hair or fur in an effort to look bigger.<\/p>\r\n<p class=\"import-Normal\"><strong>Polyandry<\/strong>: A mating system in which multiple males mate with a single breeding female.<\/p>\r\n<p class=\"import-Normal\"><strong>Polygamy<\/strong>: A mating system in which multiple males mate with multiple females.<\/p>\r\n<p class=\"import-Normal\"><strong>Polygyny<\/strong>: A mating system in which one male mates with multiple females.<\/p>\r\n<p class=\"import-Normal\"><strong>Polyspecific association<\/strong>: An association between two or more different species that involves behavioral changes in at least one of them to maintain the association.<\/p>\r\n<p class=\"import-Normal\"><strong>Primate community<\/strong>: All primate species that occur in an area.<\/p>\r\n<p class=\"import-Normal\"><strong>Primatologist<\/strong>: A scientist who studies primate behavior and\/or ecology.<\/p>\r\n<p class=\"import-Normal\"><strong>Primatology<\/strong>: The scientific field that studies primate behavior and\/or ecology.<\/p>\r\n<p class=\"import-Normal\"><strong>Ranging behavior<\/strong>: Refers to the way in which animals move about their environment.<\/p>\r\n<p class=\"import-Normal\"><strong>Receptive<\/strong>: A term used to describe females who are ready for sexual reproduction (i.e., not pregnant or nursing).<\/p>\r\n<p class=\"import-Normal\"><strong>Reproductive success<\/strong>: An individual\u2019s genetic contribution to future generations, often measured through the number of offspring produced.<\/p>\r\n<p class=\"import-Normal\"><strong>Reproductive suppression<\/strong>: The prevention or inhibition of reproduction of healthy adults.<\/p>\r\n<p class=\"import-Normal\"><strong>Resident male<\/strong>: Term that describes the male who lives with a group of females.<\/p>\r\n<p class=\"import-Normal\"><strong>Seed dispersal<\/strong>: The process by which seeds move away from the plant that produced them in preparation for germination and becoming a new plant.<\/p>\r\n<p class=\"import-Normal\"><strong>Semantic communication<\/strong>: The systematic use of signals to refer to objects in the environment.<\/p>\r\n<p class=\"import-Normal\"><strong>Sexual dimorphism<\/strong>: When males and females of a species have different morphological traits.<\/p>\r\n<p class=\"import-Normal\"><strong>Sexual selection<\/strong>: The selection for traits that increase mating success. This occurs via intersexual selection and intrasexual selection.<\/p>\r\n<p class=\"import-Normal\"><strong>Sexual swelling<\/strong>: Area of the hindquarters that change in size, shape, and often color over the course of a female\u2019s reproductive cycle, reaching maximum size at ovulation. Occurs in many primate species that live in Africa and Asia.<\/p>\r\n<p class=\"import-Normal\"><strong>Sexually monomorphic<\/strong>: When males and females of a species have similar morphological traits.<\/p>\r\n<p class=\"import-Normal\"><strong>Single-male, multi-female<\/strong>: A group that consists of one adult male, multiple adult female, and their dependent offspring.<\/p>\r\n<p class=\"import-Normal\"><strong>Single-male, single-female<\/strong>: A group that consists of one adult male, one adult female, and their dependent offspring.<\/p>\r\n<p class=\"import-Normal\"><strong>Social learning<\/strong>: The idea that new behaviors can be acquired by observing and imitating others.<\/p>\r\n<p class=\"import-Normal\"><strong>Social system<\/strong>: A way of describing the typical number of males and females of all age classes that live together.<\/p>\r\n<p class=\"import-Normal\"><strong>Social transmission<\/strong>: Transfer of something from one individual to another; this can include parasites, information, or cultural traditions.<\/p>\r\n<p class=\"import-Normal\"><strong>Sociality<\/strong>: The tendency to form social groups.<\/p>\r\n<p class=\"import-Normal\"><strong>Solitary<\/strong>: Living alone.<\/p>\r\n<p class=\"import-Normal\"><strong>Species recognition<\/strong>: The ability to differentiate conspecifics from members of other species.<\/p>\r\n<p class=\"import-Normal\"><strong>Subordinate<\/strong>: Being of low rank.<\/p>\r\n<p class=\"import-Normal\"><strong>Tactile communication<\/strong>: Conveying information through touch.<\/p>\r\n<p class=\"import-Normal\"><strong>Territory:<\/strong> A home range whose boundary is defended from intrusion by conspecifics.<\/p>\r\n<p class=\"import-Normal\"><strong>Vertebrates<\/strong>: The group of animals characterized by an internal spinal column or backbone. This includes fish, amphibians, reptiles, birds, and mammals.<\/p>\r\n<p class=\"import-Normal\"><strong>Vigilance<\/strong>: Watchful behavior used to detect potential danger, usually in the form of predators or potential competitors.<\/p>\r\n<p class=\"import-Normal\"><strong>Visual communication<\/strong>: Conveying information through signals that can be seen.<\/p>\r\n<p class=\"import-Normal\"><strong>Vocal communication<\/strong>: Conveying information through signals that can be heard.<\/p>\r\n\r\n<h2 class=\"import-Normal\">For Further Exploration<\/h2>\r\n<p class=\"import-Normal\">Goodall, Jane. 1971. <em>In the Shadow of Man<\/em>. Boston: Houghton Mifflin.<\/p>\r\n<p class=\"import-Normal\">Rowe, Noel, and Marc Myers, eds. 2016. <em>All the World\u2019s Primates. <\/em>Charleston, RI: Pogonias Press.<\/p>\r\n<p class=\"import-Normal\">Strier, Karen B. 2017. <em>Primate Behavioral Ecology.<\/em> 5th ed. New York: Routledge.<\/p>\r\n<p class=\"import-Normal\"><a href=\"https:\/\/pin.primate.wisc.edu\/\">Primate Info Net<\/a>\u00a0is an information service of the National Primate Research Center at the University of Wisconsin, Madison. It includes Primate Factsheets, primate news and publications, a list of primate-related jobs, and an international directory of primatology, among other information.<\/p>\r\n<p class=\"import-Normal\"><a href=\"https:\/\/www.primate-sg.org\/\">Primate Specialist Group<\/a>\u00a0is a collection of scientists and conservationists who work in dozens of African, Asian, and Latin American nations to promote research on primate conservation.<\/p>\r\n<p class=\"import-Normal\">Short videos of some primate behaviors discussed in this chapter:<\/p>\r\n\r\n<ul>\r\n \t<li class=\"import-Normal\">Watch vervet monkeys respond to different types of predators: BBC One. n.d. \u201cVervet Monkey\u2019s Escape Plans - Talk to the Animals: Episode 2 Preview.\u201d Accessed December 16, 2022. <a class=\"rId10\" href=\"https:\/\/www.youtube.com\/watch?v=q8ZG8Dpc8mM\">https:\/\/www.youtube.com\/watch?v=q8ZG8Dpc8mM. <\/a><\/li>\r\n \t<li class=\"import-Normal\">Watch male gelada baboons use the lip flip in competition with other males: Smithsonian Channel, June 9, 2017. \u201cWhy These Vegetarian Monkeys Have Sharp Predator Teeth.\u201d Accessed July 25, 2019. <a class=\"rId11\" href=\"https:\/\/www.youtube.com\/watch?time_continue=145&amp;v=aC6iYj_EBjY\">https:\/\/www.youtube.com\/watch?time_continue=145&amp;v=aC6iYj_EBjY<\/a>.<\/li>\r\n \t<li class=\"import-Normal\">Watch (and listen to!) howler monkeys \u201croar\u201d: Science News. N.d. \u201cHear a Male Howler Monkey Roar.\u201d Accessed November 21, 2022. <a class=\"rId12\" href=\"https:\/\/www.youtube.com\/watch?v=PYar0dkZ6v8\">https:\/\/www.youtube.com\/watch?v=PYar0dkZ6v8<\/a>.<\/li>\r\n \t<li class=\"import-Normal\">Watch Japanese macaques using natural hot springs: National Geographic. N.d. \u201cMeditative Snow Monkeys Hang Out in Hot Springs.\u201d Accessed July 25, 2019. <a class=\"rId13\" href=\"https:\/\/www.youtube.com\/watch?v=Aat9O85ynsI\">https:\/\/www.youtube.com\/watch?v=Aat9O85ynsI<\/a>.<\/li>\r\n \t<li class=\"import-Normal\">Watch chimpanzees make and use tools: National Geographic. n.d. \u201cChimps and Tools.\u201d Accessed July 25, 2019. <a class=\"rId14\" href=\"https:\/\/www.youtube.com\/watch?v=o2TBicMRLtA\">https:\/\/www.youtube.com\/watch?v=o2TBicMRLtA<\/a>.<\/li>\r\n<\/ul>\r\n<h2 class=\"import-Normal\">References<\/h2>\r\n<p class=\"import-Normal\">Aich, H., R. Moos-Heilen, and E. Zimmermann. 1990. \u201cVocalizations of Adult Gelada Baboons (<em>Theropithecus gelada<\/em>): Acoustic Structure and Behavioural Context.\u201d <em>Folia Primatologica<\/em> 55 (3\u20134): 109\u2013132.<\/p>\r\n<p class=\"import-Normal\">Bell, Sarah A. 2017. \u201cGaldikas, Birute.\u201d In <em>The International Encyclopedia of Primatology, Volume A\u2013G<\/em>, edited by Agust\u00edn Fuentes, 445\u2013446. Malden, MA: John Wiley &amp; Sons.<\/p>\r\n<p class=\"import-Normal\">Boinski, S. 1992. \u201cOlfactory Communication among Costa Rican Squirrel Monkeys: A Field Study.\u201d <em>Folia Primatologica<\/em> 59 (3): 127\u2013136.<\/p>\r\n<p class=\"import-Normal\">Cheney, D. L., and R. M. Seyfarth. 1987. \u201cThe Influence of Intergroup Competition on the Survival and Reproduction of Female Vervet Monkeys.\u201d <em>Behavioral Ecology and Sociobiology<\/em> 21 (6): 375\u2013386.<\/p>\r\n<p class=\"import-Normal\">de Oliveira Terceiro, Francisco Edvaldo, and Judith M. Burkart. 2019. \u201cCooperative Breeding.\u201d In <em>Encyclopedia of Animal Cognition and Behavior<\/em>, edited by Jennifer Vonk and Todd Shackelford, 1\u20136. Edinburg, Scotland: Springer Cham.<\/p>\r\n<p class=\"import-Normal\">Digby, Leslie J., Stephen F. Ferrari, and Wendy Saltzman. 2011. \u201cCallitrichines: The Role of Competition in Cooperatively Breeding Species.\u201d In <em>Primates in Perspective<\/em>, edited by Christina J. Campbell, August\u00cdn Fuentes, Katherine C. MacKinnon, Simon K. Bearder, and Rebecca M. Stumpf, 91\u201310. 2nd edition. New York: Oxford University Press.<\/p>\r\n<p class=\"import-Normal\">Fischer, Julia, Kurt Hammerschmidt, Dorothy L. Cheney, and Robert M. Seyfarth. 2008. \u201cAcoustic Features of Female Chacma Baboon Barks.\u201d <em>Ethology<\/em> 107 (1): 33\u201354.<\/p>\r\n<p class=\"import-Normal\">Jolly, Alison. 1966. <em>Lemur Behavior: A Madagascar Field Study<\/em>. Chicago: University of Chicago Press.<\/p>\r\n<p class=\"import-Normal\">Krief, Sabrina, Claude Marcel Hladik, and Claudie Haxaire. 2005. \u201cEthnomedicinal and Bioactive Properties of Plants Ingested by Wild Chimpanzees in Uganda.\u201d <em>Journal of Ethnopharmacology<\/em> 110 (1\u20133): 1\u201315.<\/p>\r\n<p class=\"import-Normal\">Maekawa, Mkio, Annette Lanjouw, Eug\u00e8ne Rutagarama, and Doublas Sharp. 2013. \u201cMountain Gorilla Tourism Generating Wealth and Peace in Post-Conflict Rwanda.\u201d <em>Natural Resources Forum<\/em> 37 (2): 127\u2013137.<\/p>\r\n<p class=\"import-Normal\">Matsuzawa, Tetsuro. 2015. \u201cSweet-Potato Washing Revisited: 50th Anniversary of the <em>Primates<\/em> Article.\u201d <em>Primates<\/em> 56: 285\u2013287.<\/p>\r\n<p class=\"import-Normal\">Matsuzawa, Tetsuro. 2018. \u201cHot-Spring Bathing of Wild Monkeys in Shiga-Heights: Origin and Propagation of a Cultural Behavior.\u201d <em>Primates<\/em> 59: 209\u2013213.<\/p>\r\n<p class=\"import-Normal\">McGrew, W. C. 1998. \u201cCulture in Nonhuman Primates?\u201d <em>Annual Review of Anthropology<\/em> 27: 301\u2013328.<\/p>\r\n<p class=\"import-Normal\">Mertl-Millhollen, Anne S. 1988. \u201cOlfactory Demarcation of Territorial but Not Home Range Boundaries by <em>Lemur catta<\/em>.\u201d <em>Folia Primatologica<\/em> 50 (3\u20134): 175\u2013187.<\/p>\r\n<p class=\"import-Normal\">Pinacho-Guendulain, B., and G. Ramos-Fern\u00e1ndez. 2017. \u201cInfluence of Fruit Availability on the Fission-Fusion Dynamics of Spider Monkeys (<em>Ateles geoffroyi<\/em>).\u201d <em>International Journal of Primatology<\/em> 38: 466\u2013484.<\/p>\r\n<p class=\"import-Normal\">Poirotte, Cl\u00e9mence, Fran\u00e7ois Massol, Ana\u00efs Herbert, Eric Willaume, Pacelle M. Bomo, Peter M. Kappeler, and Marie J. E. Charpentier. 2017. \u201cMandrills Use Olfaction to Socially Avoid Parasitized Conspicifics.\u201d <em>Science Advances<\/em> 3 (4): e160172.<\/p>\r\n<p class=\"import-Normal\">Rodrigues, Michelle. 2019. \u201cIt\u2019s Time to Stop Lionizing Dian Fossey as a Conservation Hero.\u201d <em>Lady Science<\/em> website, September 20. Accessed December 14, 2022. <a class=\"rId15\" href=\"https:\/\/www.ladyscience.com\/ideas\/time-to-stop-lionizing-dian-fossey-conservation\">https:\/\/www.ladyscience.com\/ideas\/time-to-stop-lionizing-dian-fossey-conservation<\/a>.<\/p>\r\n<p class=\"import-Normal\">Samuni, Liran, Anna Preis, Tobias Deschner, Catherine Crockford, and Roman M. Wittig. 2018. \u201cReward of Labor Coordination and Hunting Success in Wild Chimpanzees.\u201d <em>Communications Biology<\/em> 1: 138.<\/p>\r\n<p class=\"import-Normal\">Santana, Sharlene E., Jessica Lynch Alfaro, and Michael E. Alfaro. 2012. \u201cAdaptive Evolution of Facial Colour Patterns in Neotropical Primates.\u201d <em>Proceedings of the Royal Society B: Biological Sciences<\/em> 279 (1736): 2204\u20132211.<\/p>\r\n<p class=\"import-Normal\">Sanz, Crickette M., David Strait, Crepin Eyana Ayina, Jean Marie Massamba, Thierry Fabrice Ebombi, Severin Ndassoba Kialiema, Delon Ngoteni, et al. 2022. \u201cInterspecific Interactions Between Sympatric Apes.\u201d i<em>Science<\/em> 25 (10): 105059.<\/p>\r\n<p class=\"import-Normal\">Sch\u00f6n Ybarra, M. A. 1986. \u201cLoud Calls of Adult Male Red Howling Monkeys (<em>Alouatta seniculus<\/em>).\u201d <em>Folia Primatologica<\/em> 47 (4): 204\u2013216.<\/p>\r\n<p class=\"import-Normal\">Setchell, Joanna M., Tessa Smith, E. Jean Wickings, and Leslie A. Knapp. 2008. \u201cSocial Correlates of Testosterone and Ornamentation in Male Mandrills.\u201d <em>Hormones and Behavior<\/em> 54 (3): 365\u2013372.<\/p>\r\n<p class=\"import-Normal\">Setchell, Joanna M., E. Jean Wickings, and Leslie A. Knapp. 2006. \u201cSignal Content of Red Facial Coloration in Female Mandrills (<em>Mandrillus sphinx<\/em>).\u201d <em>Proceedings of the Royal Society B: Biological Sciences<\/em><a class=\"rId16\" href=\"https:\/\/paperpile.com\/b\/Gb7Zko\/Lxpl\"> 273 (1599): 2395\u20132400.<\/a><\/p>\r\n<p class=\"import-Normal\">Seyfarth, R. M., D. L. Cheney, and P. Marler. 1980a. \u201cMonkey Responses to Three Different Alarm Calls: Evidence of Predator Classification and Semantic Communication.\u201d <em>Science<\/em> 210 (4471): 801\u2013803.<\/p>\r\n<p class=\"import-Normal\">Seyfarth, Robert M., Dorothy L. Cheney, and Peter Marler. 1980b. \u201cVervet Monkey Alarm Calls: Semantic Communication in a Free-Ranging Primate.\u201d <em>Animal Behaviour<\/em> 28 (4): 1070\u20131094.<\/p>\r\n<p class=\"import-Normal\">Sharma, Goutam, Chan Ram, and Lal Singh Rajpurohit. 2010. \u201cA Case Study of Infantcide After Resident Male Replacement in <em>Semnopithecus entellus<\/em> around Jodhpur (India).\u201d <em>Proceeding of the Zoological Society<\/em> 63 (2): 93\u201398.<\/p>\r\n<p class=\"import-Normal\">Shirasu, Mika, Satomi Ito, Akihiro Itoigawa, Takashi Hayakawa, Kodzue Kinoshita, Isao Munechika, Hiroo Imai, and Kazushige Touhara. 2020. \u201cKey Male Glandular Odorants Attracting Female Ring-Tailed Lemurs.\u201d <em>Current Biology<\/em> 30 (11): 2131\u20132138.<\/p>\r\n<p class=\"import-Normal\">Stanford, Craig B. 2017. \u201cGoodall, Jane.\u201d In <em>The International Encyclopedia of Primatology, Volume A\u2013G<\/em>, edited by Agust\u00edn Fuentes, 471\u2013472. Malden, MA: John Wiley &amp; Sons.<\/p>\r\n<p class=\"import-Normal\">Stewart, Kelly. 2017. \u201cFossey, Dian.\u201d In <em>The International Encyclopedia of Primatology, Volume A\u2013G<\/em>, edited by Agust\u00edn Fuentes, 432\u2013433. Malden, MA: John Wiley &amp; Sons.<\/p>\r\n<p class=\"import-Normal\">Takeshita, Rafaela S.C., Fred B. Bercovitch, Kodzue Kinoshita, and Michael A. Huffman. 2018. \u201cBeneficial Effect of Hot Spring Bathing on Stress Levels in Japanese Macaques.\u201d <em>Primates<\/em> 59 (3): 215\u2013225.<\/p>\r\n<p class=\"import-Normal\">Trivers, Robert L. 1972. \u201cParental Investment and Sexual Selection.\u201d In <em>Sexual Selection and the Descent of Man, 1871\u20131971<\/em>, edited by Bernard Campbell, 136\u2013179. Chicago: Aldine.<\/p>\r\n<p class=\"import-Normal\">Whiten, Andrew. 2011. \u201cThe Scope of Culture in Chimpanzees, Humans and Ancestral Apes.\u201d <em>Philosophical Transactions of the Royal Society of London B: Biological Sciences<\/em> 366 (1567): 997\u20131007.<\/p>\r\n<p class=\"import-Normal\">Wiens, Frank, and Annette Zitzmann. 2003. \u201cSocial Structure of the Solitary Slow Loris <em>Nycticebus coucang<\/em> (Lorisidae).\u201d <em>Journal of Zoology<\/em> 261 (1): 35\u201346.<\/p>\r\n<p class=\"import-Normal\">Zuberb\u00fchler, Klaus, David Jenny, and Redouan Bshary. 1999. \u201cThe Predator Deterrence Function of Primate Alarm Calls.\u201d <em>Ethology<\/em> 105 (6): 477\u2013490.<\/p>\r\n<p class=\"import-Normal\">Zuberb\u00fchler, Klaus, Ronald No\u00eb, and Robert M. Seyfarth. 1997. \u201cDiana Monkey Long-Distance Calls: Messages for Conspecifics and Predators.\u201d <em>Animal Behaviour<\/em> 53 (3): 589\u2013604.<\/p>\r\n\r\n<h2 class=\"import-Normal\">Acknowledgments<\/h2>\r\n<p class=\"import-Normal\">The author is grateful to the editors for the opportunity to contribute to this open-source textbook. She thanks Dr. Stephanie Etting for her encouragement and support during the revision of this chapter. Her suggestions, along with comments made by two anonymous reviewers on an earlier draft of this chapter, improved the final version considerably. Finally, she thanks all the primatologists who came before her, especially her advisor, Lynne A. Isbell, for their tireless efforts to understand the behavior and ecology of the living primates. Without their work, this chapter would not have been possible.<\/p>\r\n\r\n<\/div>","rendered":"<div class=\"__UNKNOWN__\">\n<p class=\"import-Normal\">Karin Enstam Jaffe, Ph.D., Sonoma State University<\/p>\n<p class=\"import-Normal\"><em>This chapter is a revision from <\/em><em>&#8220;<\/em><a class=\"rId6\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-6\/\"><em>Chapter 6: Primate Ecology and Behavior<\/em><\/a><em>\u201d by Karin Enstam Jaffe. In <\/em><a class=\"rId7\" 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=\"rId8\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\"><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\"><span style=\"color: #000000\">Learning Objectives<\/span><\/h2>\n<\/header>\n<div class=\"textbox__content\">\n<ul>\n<li class=\"import-Normal\">Describe the variables that affect primate diets.<\/li>\n<li class=\"import-Normal\">Explain how primates interact with other organisms in their environment.<\/li>\n<li class=\"import-Normal\">Discuss why primates live in groups, types of primate groups, and components of their social systems.<\/li>\n<li class=\"import-Normal\">Describe the reproductive strategies of males and females.<\/li>\n<li class=\"import-Normal\">Explain the ways in which primates communicate.<\/li>\n<li class=\"import-Normal\">Discuss the evidence for primate cultural traditions.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<p class=\"import-Normal\">Nonhuman primates (hereafter, \u201cprimates\u201d) are a fascinating group of animals, whose similarity to humans can be striking. Because of this similarity, studying primates helps anthropologists to gain insight into how our human ancestors may have behaved. It also allows us to better understand our own behavior through <strong>comparison<\/strong> (examining similarities and differences) with other primates as well as by comparing different species of primates to one another. In this way, studying primates helps anthropologists comprehend humanity from a biological perspective, which contributes to anthropology\u2019s commitment to <strong>holism,<\/strong> the idea that the parts of a system interconnect and interact to make up the whole.<\/p>\n<figure style=\"width: 242px\" class=\"wp-caption alignleft\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2023\/05\/image3.png\" alt=\"A person using binoculars to look at monkeys.\" width=\"242\" height=\"354\" \/><figcaption class=\"wp-caption-text\">Figure 7.1: The author observing patas monkeys from a distance in Laikipia, Kenya. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-6\/\">Karin Enstam Jaffe observing patas monkeys in Laikipia, Kenya (Figure 6.5)<\/a> by Rebecca Chancellor is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\"> CC BY-NC 4.0 License<\/a>.<\/figcaption><\/figure>\n<p><strong>Ethology <\/strong>is the study of animal behavior, while <strong>primatology <\/strong>is the study of primate behavior. People who study primates are called <strong>primatologists<\/strong>. Research on primates can be conducted in the field (i.e., on wild primates) or in captivity (i.e., zoos) and may or may not involve experiments, such as playing recorded alarm calls to see how individuals react. Unlike some other Science, Technology, Engineering, and Math (STEM) fields, primatology has a long history of research conducted by women (see \u201cSpecial Topic: Women in Primatology\u201d). Primatologists come from many different disciplines, have diverse backgrounds, and study primates for different reasons. Biologists study primates as examples of evolutionary theories like natural selection, and to understand behaviors as <strong>adaptations<\/strong>, or traits with a function that increases <strong>fitness<\/strong>, i.e. an individual\u2019s survival and\/or reproduction. Primate intelligence is of interest to psychologists who want to learn more about deception or cooperation and to linguists interested in the principles of communication and language. Ecologists consider how primates interact with the habitats they occupy, and conservationists examine how primates are affected by deforestation, poaching, or illegal animal trade (see Appendix B: Primate Conservation for more information on these topics). Biological anthropologists, like myself (Figure 7.1), who study primates are interested in learning about their social complexity, and ecological and behavioral variation, to better understand the biological basis of human behavior. And, similar to biologists, we also explore how primate behavior is adaptive and contributes to individual fitness. Like other sciences, primatology is only as strong as its researchers, methods, and theories, and the field has benefitted recently from efforts to increase diversity and reckon with its colonialist past, as discussed below in \u201cSpecial Topic: Women in Primatology.\u201d<\/p>\n<p class=\"import-Normal\">Humans share many traits in common with primates. As you learned in Chapter 5, some of these traits are similar due to <strong>homology<\/strong>, traits both species inherited from a common primate ancestor. For example, like most other primates, humans are social animals who live in groups. Group living did not evolve independently in humans and other primates. Rather, group living is a trait that evolved in a primate ancestor, and because it benefited survival, it was retained in the species\u2019 <strong>descendants<\/strong> (or the species that come after the ancestor species). In contrast, humans and other primates can have similar traits that evolved independently, which is called <strong>analogy<\/strong>. For example, both humans and Japanese macaques (<em>Macaca fuscata<\/em>) use natural hot springs (Figures 7.2a-b). Research on these monkeys indicates that sitting in hot springs reduces stress and helps keep them warm, much as it does for humans (Takeshita et al. 2018). But this behavior is not the result of humans and Japanese macaques having a shared ancestor who used hot springs. Rather, the behavior arose independently in two species that both occupy northerly environments and adapted to cold climates using a similar behavior. Studying the homologous traits we share with other primates, like living in groups, helps us develop hypotheses about human behaviors as adaptations, which in turn helps us develop models for the behavior of our human ancestors. Studying analogous traits, like hot springs use, allows us to better understand the effects of ecological variables on morphology and behavior of both primates and humans, living and extinct.<\/p>\n<figure id=\"attachment_191\" aria-describedby=\"caption-attachment-191\" style=\"width: 2161px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-189 size-full\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/6.2.jpg\" alt=\"Left, a man in a hot spring. Right, monkeys in a hot spring.\" width=\"2161\" height=\"803\" \/><figcaption id=\"caption-attachment-191\" class=\"wp-caption-text\">Figure 7.2a-b: Both humans (left) and Japanese macaques (right) use natural hot springs to reduce stress and relax. This similar trait arose independently in the two species, making it a good example of analogy. Credit: a. <a href=\"https:\/\/pixabay.com\/photos\/hot-spring-landscape-man-mountain-1846721\/\">Hot Spring Landscape<\/a> by <a href=\"https:\/\/pixabay.com\/users\/pexels-2286921\/?utm_source=link-attribution&amp;utm_medium=referral&amp;utm_campaign=image&amp;utm_content=1846721\">Pexels<\/a> has been modified (cropped) and has been designated to the <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/cc0\/\">public domain (CC0)<\/a> under a <a href=\"https:\/\/pixabay.com\/service\/terms\/#license\">Pixabay License<\/a>. b. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Jigokudani_hotspring_in_Nagano_Japan_001.jpg\">Jigokudani hotspring in Nagano Japan 001<\/a> by Yosemite 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<div class=\"textbox\">\n<h2 class=\"import-Normal\">Special Topic: Women in Primatology<\/h2>\n<p class=\"import-Normal\">While many STEM fields have traditionally been, and continue to be, dominated by men, primatology has a long history of significant research conducted by women. This is due, in part, to the fact that three of the most well-known primatologists are women. In the early 1960s, British paleoanthropologist Louis Leakey (discussed in Chapters 9 and 10) was looking for students to study the great apes in hopes of shedding light on the behaviors of our early ancestors. He chose Jane Goodall (Figure 7.3a) to study chimpanzees (<em>Pan troglodytes<\/em>), Birute Galdikas (Figure 7.3b) to study Bornean orangutans (<em>Pongo pygmaeus<\/em>), and Dian Fossey (Figure 7.3c) to study mountain gorillas (<em>Gorilla<\/em><em> beringei beringei<\/em>). The work of these three women, sometimes referred to as Leakey\u2019s \u201cTrimates,\u201d has transformed our understanding of ape (and primate) behavior.<\/p>\n<figure id=\"attachment_190\" aria-describedby=\"caption-attachment-190\" style=\"width: 626px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-190\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/6.3-1.jpg\" alt=\"Jane Goodall, Birute Galdikas, and Dian Fossey.\" width=\"626\" height=\"209\" \/><figcaption id=\"caption-attachment-190\" class=\"wp-caption-text\">Figure 7.3a-c: Louis Leakey\u2019s \u201cTrimates\u201d (left to right): a. Jane Goodall\u2019s research on the Gombe chimpanzees spans over half a century; b. Birute Galdikas\u2019s research and rescue work on behalf of orangutans spans 40 years; c. Dian Fossey studied mountain gorillas in Rwanda for almost 20 years, until her murder in 1985. Credit: a. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Jane_Goodall_HK.jpg\">Jane Goodall HK<\/a> by Jeekc has been modified (cropped) and is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\"> CC BY-SA 3.0 License<\/a>. b. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Dr_Birute_Galdikas.jpg\">Dr Birute Galdikas<\/a> by<a href=\"https:\/\/www.flickr.com\/photos\/sfupamr\/\"> Simon Fraser University &#8211; University Communications<\/a> has been modified (cropped) and is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/legalcode\"> CC BY 2.0 License<\/a>. c. <a href=\"https:\/\/www.flickr.com\/photos\/mary-lynn\/2925879356\">US-223658 Dian Fossey<\/a> by<a href=\"https:\/\/www.flickr.com\/photos\/mary-lynn\/2925879356\/\"> Mary-Lynn<\/a> has been modified (cropped) and is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/\"> CC BY 2.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">Arriving at the Gombe Stream Reserve in Tanzania in 1960, Jane Goodall was one of the first scientists to conduct a long-term study of wild nonhuman primates. Before then, most studies lasted less than a year and were often zoo-based. By 1961, she had made two astounding observations that forced us to reconsider what differentiates humans from the rest of the primate order. She observed chimpanzees eating a colobus monkey, the first reported evidence of meat eating in our closest relatives (she later observed them hunting and sharing meat). And she discovered that chimpanzees make and use tools by stripping leaves off twigs to \u201cfish\u201d for termites. Her work, spanning several decades, has produced long-term data on chimpanzee mating strategies, mother-infant bonds, and aggression. In the mid-1980s, Goodall transitioned from field researcher to conservationist and activist, advocating for the humane use of nonhuman animals (Stanford 2017).<\/p>\n<p class=\"import-Normal\">Birute Galdikas began her study of orangutans in Kalimantan, Borneo, in 1971. Hers was the first long-term study conducted on the Bornean orangutan. Galdikas and her colleagues have collected over 150,000 hours of observational data, focusing on the life histories of individual orangutans. While conducting behavioral research, Galdikas discovered that the pet trade and habitat loss were adversely affecting the orangutan population. Eventually, Galdikas\u2019s conservation efforts began to extend beyond advocacy and into rehabilitation and forest preservation (Bell 2017). If you would like to learn more about primate conservation efforts, please see Appendix B: Primate Conservation.<\/p>\n<p class=\"import-Normal\">In 1967, Dian Fossey began her long-term study of mountain gorillas and founded the Karisoke Research Center in Rwanda. Her and her colleagues\u2019 research, over several decades, revealed much about gorilla social behavior, ecology, and life history. Her efforts also led to the development of mountain gorilla conservation programs. However, she was a controversial figure, as discussed below. Fossey was murdered in December 1985; the case remains unsolved (Stewart 2017).<\/p>\n<h3 class=\"import-Normal\"><strong>Decolonizing Primatology<\/strong><\/h3>\n<p class=\"import-Normal\">Recently, the movement to <strong>decolonize<\/strong> primatology, by understanding and highlighting the theories and research of non-Western individuals and perspectives, has gathered steam. This movement draws attention to the maltreatment of local people by Western primatologists. For example, Michelle Rodrigues (2019) argues that it&#8217;s time we stop focusing on the scientific and conservation contributions of Dian Fossey and acknowledge that her &#8220;active conservation&#8221; techniques included kidnapping and torturing local Rwandans who were known as, or suspected to be, gorilla poachers. Rodrigues (2019) argues:<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 36pt;text-indent: 0pt\">The image of Fossey, a white American woman, whipping and torturing black African poachers is evocative of the behavior of white slaveholders in the American South. It is appalling enough to think of that behavior occurring in the 1850s; there is no way we can explain Fossey\u2019s behavior in the 1970s as the product of \u201ca different time.\u201d Yet, almost three decades later, the romantic notion of a noble martyr who died for her devotion to gorillas prevails, and these terrifying actions are often described as simply unorthodox methods. Perhaps these truths are softened due to fears that the reality of this legacy would harm gorilla conservation efforts. But memorializing her as a martyr and patron saint of gorilla conservation demands that we forget the cruel acts she advocated for and performed.<\/p>\n<p class=\"import-Normal\">Further, Louis Leakey\u2019s installment of Goodall, Galdikas, and Fossey to study chimpanzees, orangutans, and mountain gorillas, respectively, is itself viewed as recapitulating the colonial legacy in Africa and Asia. Given that Leakey was the offspring of British missionaries, Rodrigues (2019) argues, it is no accident that he was willing to mentor British and American women, while overlooking women from Africa and Asia as potential researchers. This leads us to another level of the decolonizing movement, which aims to highlight the research of non-Western primatologists, particularly those living in what primatologists refer to as \u201chabitat countries\u201d that are home to living primates. As you will see in this chapter, scientists from diverse backgrounds are active contributors to exciting research on primates around the world.<\/p>\n<\/div>\n<h2 class=\"import-Normal\">Ecology<\/h2>\n<p class=\"import-Normal\">The more than 600 species and subspecies of living primates are highly diverse in their dietary preferences and the habitats they occupy. In this section we\u2019ll briefly discuss aspects of <strong>ecology<\/strong>, or the relationship between organisms and their physical surroundings, that impact a primate\u2019s life, the foods they eat, and the other species with whom they interact.<\/p>\n<h3 class=\"import-Normal\"><strong>Primate Diets<\/strong><\/h3>\n<p class=\"import-Normal\">Diet may be the most important variable influencing variation in primate morphology, behavior, and ecology. Most primates are <strong>omnivores<\/strong> who ingest a variety of foods in order to obtain appropriate levels of protein, carbohydrates, fats, and fluids, but one type of food often makes up the majority of each species\u2019 diet. You learned about the dental and digestive adaptations of <strong>frugivores<\/strong> (who feed primarily on fruit), <strong>folivores<\/strong> (whose diet consists mostly of leaves), and <strong>insectivores <\/strong>(who eat mainly insects) in Chapter 5, so we will not discuss them again here.<\/p>\n<h4 class=\"import-Normal\"><em>Body Size and Diet<\/em><\/h4>\n<figure id=\"attachment_191\" aria-describedby=\"caption-attachment-191\" style=\"width: 559px\" class=\"wp-caption alignright\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-191\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/6.4-1.jpg\" alt=\"A tarsier eats a grasshopper. A gorilla eats leaves.\" width=\"559\" height=\"237\" \/><figcaption id=\"caption-attachment-191\" class=\"wp-caption-text\">Figure 7.4a-b: Primates eat different types of food. Small primates, like the spectral tarsier (left), eat mostly insects while large primates, like the mountain gorilla (right), eat mostly leaves. Credit: a. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Spectral_Tarsier_Tarsius_tarsier_(7911549768).jpg\">Spectral Tarsier Tarsius tarsier (7911549768)<\/a> by<a href=\"https:\/\/www.flickr.com\/people\/65695019@N07\"> Bernard DUPONT<\/a> has been modified (cropped) and is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\"> CC BY-SA 2.0 License<\/a>. b. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Mountain_gorilla_(Gorilla_beringei_beringei)_eating.jpg\">Mountain gorilla (Gorilla beringei beringei) eating<\/a> by<a href=\"https:\/\/www.sharpphotography.co.uk\/\"> Charles J Sharp<\/a> (creator QS:P170,Q54800218) has been modified (cropped) 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>Insects are a high-quality food, full of easily digestible protein and high in calories that meet most of a primate\u2019s dietary needs. Although all primates will eat insects if they come upon them, those species that rely most heavily on insects tend to be the smallest. Why? Because larger primates simply cannot capture and consume enough insects every day to survive. Because of their small size (less than 150 g), spectral tarsiers (<em>Tarsius spectrum<\/em>) have a fast <strong>metabolism<\/strong>, which means they turn food to energy quickly, but they do not need to consume large amounts of food each day. It does not matter to a spectral tarsier that a grasshopper only weighs 300 mg, because the tarsier (<em>Tarsius<\/em>) itself is so small that one grasshopper is a good-size meal (Figure 7.4a). That same grasshopper is not even a snack for an adult male mountain gorilla (<em>Gorilla beringei beringei<\/em>), who may weigh up to 200 kg. Fortunately for gorillas (<em>Gorilla)<\/em>, their large body size means they have a slow metabolism, converting food into energy much more slowly, so they can eat lower quality food that takes longer to digest, provided there is a lot of it. For gorillas, leaves, which are hard to digest but plentiful, fit the bill (Figure 7.4b). Most medium-sized primates are highly frugivorous, and supplement their fruit based diet in ways that correspond with their size: Smaller frugivores tend to supplement with insects, while larger frugivores tend to supplement with leaves.<\/p>\n<\/div>\n<div class=\"__UNKNOWN__\">\n<h4 class=\"import-Normal\"><em>Food Abundance and Distribution<\/em><\/h4>\n<p class=\"import-Normal\">Nutrients are not the only dietary considerations primates must make. They must also ensure that they consume more calories than they use. The abundance and distribution of food affect energy expenditure and calorie intake because they determine how far animals must travel in search of food and how much they must compete to obtain it. <strong>Abundance <\/strong>refers to how much food is available in a given area while <strong>distribution<\/strong> refers to how food is spread out. In terms of abundance, food is either plentiful or scarce (Figure 7.5a\u2013b). Food is distributed in one of three ways: uniformly (Figure 7.6a), in clumps (Figure 7.6b), or randomly (Figure 7.6c). In general, higher-quality foods, like fruit and insects, are less abundant and have patchier distributions than lower-quality foods, like leaves. Primates who eat fruit or insects usually have to travel farther to find food and burn more calories in the process. Abundance and distribution of food is another reason why larger primates tend to rely more heavily on leaves than either fruit or insects.<\/p>\n<figure style=\"width: 619px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image2-2.png\" alt=\"Two squares with different amounts of dots.\" width=\"619\" height=\"286\" \/><figcaption class=\"wp-caption-text\">Figure 7.5a-b: Two types of food abundance. Food is plentiful when there is a lot of it in a given area (left). Food is scarce when there is not very much of it in a given area (right). Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-6\/\">Food abundance and food scarcity (Figure 6.7)<\/a> by Karin Enstam Jaffe 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>.<\/figcaption><\/figure>\n<figure style=\"width: 690px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" style=\"font-size: 1em\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image4-2.png\" alt=\"Three squares with dots in different formations.\" width=\"690\" height=\"214\" \/><figcaption class=\"wp-caption-text\">Figure 7.6a-c: Three types of food distribution. a. Food has a uniform distribution when it is spread out evenly in the environment. b. Food has a clumped distribution when it is found in patches. c. Food is randomly distributed when it has neither uniform nor clumped distribution. Credit: <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/__unknown__-6\/\">Food distribution patterns (Figure 6.8)<\/a> by Karin Enstam Jaffe 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>.<\/figcaption><\/figure>\n<h3 class=\"import-Normal\"><strong>Community Ecology<\/strong><\/h3>\n<p class=\"import-Normal\">Primates are members of broader ecological communities composed of other species, including other primates, predators, parasites, and even humans. <strong>Community ecology<\/strong> deals with the relationships and interactions between different organisms that occupy the same habitat. Interactions with <strong>conspecifics <\/strong>(members of the same species) and <strong>heterospecifics<\/strong> (members of different species) are critical aspects of ecological communities. Some habitats support highly diverse <strong>primate communities<\/strong> consisting of 10 or more primate species. How can so many primate species occupy the same area and avoid competition? In most cases, the primate species that live together occupy different <strong>niches<\/strong>, which means they do not meet their needs for food and shelter in the exact same way. Two species can avoid competition by eating different kinds of food, living at different levels of a forest, or even searching for food at different times of day. Because tropical rainforests, like Manu National Park in Peru, are highly variable, with many habitats and many sources of food and shelter, there are many different niches for multiple species to exploit, and large primate communities can result (Figure 7.7).<\/p>\n<figure style=\"width: 710px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image5-1-1.png\" alt=\"Eight primate species.\" width=\"710\" height=\"550\" \/><figcaption class=\"wp-caption-text\">Figure 7.7: Eight of the 14 primate species in Manu National Park, Peru. Top row, left to right: Goeldi\u2019s marmoset (Callimico goeldi), Rio Tapaj\u00f3s saki (Pithecia irrorata), tufted capuchin (Sapajus apella); middle row, left to right: emperor tamarin (Saguinus imperator), black-headed night monkey (Aotus nigriceps), Bolivian red howler (Alouatta sara); bottom row, left to right: black-capped squirrel monkey (Saimiri boliviensis), Peruvian spider monkey (Ateles chamek). Credit: Primate species in Manu National Park original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Karin Jaffe 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:\/\/www.flickr.com\/photos\/31223088@N08\/5582747190\/\">Tamarin Baby\/Goeldi\u2019s Monkey<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/31223088@N08\/\">stefan_fotos<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/\">CC BY 2.0 License<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Pithecia_irrorata_-Brazil-8b.jpg\">Pithecia irrorata -Brazil-8b<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/9092428@N04\">Ana_Cotta<\/a>, modified (cropped), <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/deed.en\">CC BY 2.0 License<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Tufted_capuchin_on_a_branch_in_Singapore.jpg\">Tufted Capuchin on a Branch in Singapor<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Basile_Morin\">Basile_Morin<\/a>, modified (cropped), <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/deed.en\">CC BY-SA 4.0 License<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Tamarin_portrait.JPG\">Tamarin Portrait<\/a> by <a href=\"https:\/\/sites.google.com\/site\/thebrockeninglory\/?pli=1\">Brocken Inaglory<\/a>, modified (cropped), <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/deed.en\">CC BY-SA 3.0 License<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Aotus_nigriceps_1.jpg\">Aotus nigriceps 1<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/dusantos_bh\/\">DuSantos<\/a>, modified (cropped), <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/deed.en\">CC BY 2.0 License<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Alouatta_sara_%28Bolivian_red_howler%29.jpg\">Aloutta sara (Bolivian Red Howler)<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/nacho_dayz\/\">Raul Ignacio<\/a>, modified (cropped), <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/\">CC BY-SA 2.0 License<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Black-capped_squirrel_monkey_%28Chalalan%29.jpg\">Black-Capped Squirrel Monkey (Chalalan)<\/a> by <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Rodrigo_Mariaca\">Rodrigo Mariaca<\/a>, modified (cropped), <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/deed.en\">CC BY-SA 4.0 License<\/a>; <a href=\"https:\/\/www.flickr.com\/photos\/eye1\/3185562151\/\">Maquisapa (Spider Monkey)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/eye1\/\">Ivan Mlinaric<\/a>, modified (cropped), <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/\">CC BY 2.0 License<\/a>].<\/figcaption><\/figure>\n<h4 class=\"import-Normal\"><em>Competitive Interactions<\/em><\/h4>\n<p class=\"import-Normal\">Although species living in the same location often occupy different niches to avoid competition, when a resource that is important for survival or reproduction is scarce, individuals will compete to obtain that resource. This is a central tenet of Charles Darwin\u2019s theory of evolution by natural selection (see Chapter 2). Competition between primates takes two forms: Individuals engage in <strong>direct competition<\/strong>, which involves physical interaction between individuals (such as fighting), over resources that are large and worth defending (fruit is a good example of a food resource over which primates will fight). Individuals engage in <strong>indirect competition<\/strong>, in which there is no physical interaction between individuals, when a resource is small. Primates often engage in indirect competition for insects, like grasshoppers, that are eaten quickly, often before another individual arrives on the scene. Primates may engage in direct and\/or indirect competition with members of their own group, with members of other groups of conspecifics, or with heterospecifics.<\/p>\n<h4 class=\"import-Normal\"><em>Predator-Prey Interactions<\/em><\/h4>\n<p class=\"import-Normal\">The plants and animals that primates eat are an important part of their ecological community. In addition to insects, many primates incorporate some <strong>vertebrate<\/strong> (animals with an internal spinal column or backbone) prey into their diet. Often, predation by primates is opportunistic, occurring because the prey happens to be in the right place at the right time. I\u2019ve observed vervets (<em>Chlorocebus pygerythrus<\/em>) opportunistically killing lizards by smashing them against a rock or tree trunk and eating them. More rarely, hunting is deliberate and cooperative. In some chimpanzee (<em>Pan troglodytes<\/em>) populations, hunts involve multiple individuals, each of whom plays a specific role and is rewarded afterward with a share of the prey that has been captured (Samuni et al. 2018).<\/p>\n<p class=\"import-Normal\">All primates are susceptible to predation by mammalian <strong>carnivores <\/strong>(animals whose diet consists primarily of animal tissue (e.g., Figure 7.8a), reptiles (e.g., Figure 7.8b), or birds of prey (e.g., Figure 7.8c). Although the specific predators found in an ecological community differ based on geography, smaller primates always fall prey to a wider range of predators. Because predators are diverse in their hunting tactics, primates have evolved a wide range of tactics to avoid or escape them. We will discuss some of these behavioral adaptations later in this chapter in the section titled \u201cWhy Do Primates Live in Groups?.\u201d<\/p>\n<p>&nbsp;<\/p>\n<\/div>\n<figure id=\"attachment_210\" aria-describedby=\"caption-attachment-210\" style=\"width: 765px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-195\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/6.8-scaled-1.jpg\" alt=\"A leopard, python, and harpy eagle.\" width=\"765\" height=\"229\" \/><figcaption id=\"caption-attachment-210\" class=\"wp-caption-text\">Figure 7.8a-c: Examples of primate predators: the Indian leopard (Panthera fusca) is an example of a mammalian carnivore (top left), the South African python (Python natalensis) is an example of a reptilian predator (bottom left), and the harpy eagle (Harpia harpyja) of Central and South America is an example of a bird of prey (right). Credit: a. <a href=\"https:\/\/www.flickr.com\/photos\/srikaanth-sekar\/9814267145\/\">Leopard<\/a> by<a href=\"https:\/\/www.flickr.com\/people\/srikaanth-sekar\/\"> Srikaanth Sekar<\/a> has been modified (cropped) and is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/\"> CC BY-SA 2.0 License<\/a>. b. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Python_natalensis_G._J._Alexander.JPG\">Python natalensis G. J. Alexander<\/a> by Graham J. Alexander, University of the Witwatersrand, USGS, is in the<a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\"> public domain<\/a>. c. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Harpy_Eagle_clutching_captured_bird_-_Itirapina_Reserve.jpg\">Harpy Eagle clutching captured bird &#8211; Itirapina Reserve<\/a> by Jonathan Wilkins has been modified (cropped) and 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<div class=\"__UNKNOWN__\">\n<h4 class=\"import-Normal\"><em>Mutualistic Interactions<\/em><\/h4>\n<p class=\"import-Normal\">So far, we&#8217;ve discussed competitive and predator-prey interactions in primate communities. But there are some interactions (between different primate species and between primates and other species) that are <strong>mutualistic<\/strong>, which is when organisms of different species work together, each benefiting from the interaction or relationship. One example is <strong>seed dispersal<\/strong>, which is the process by which seeds move away from the plant that produced them in preparation for germination and becoming a new plant. When seeds are dispersed by animals, like primates, it is an example of mutualism. The primate eats the fruit of a plant, which provides nutrients for its body, and in the process ingests the plant\u2019s seeds. Later, it deposits the seeds at another location as a pile of fertilizer.<\/p>\n<p class=\"import-Normal\">Another example of mutualism is <strong>polyspecific associations<\/strong>, which are associations between two or more different species that are maintained by behavioral changes by at least one of the species. While some associations are short in duration, others are semi-permanent. The mutualistic benefits of polyspecific associations include one species gaining access to food that would otherwise have been inaccessible or being alerted to the presence of predators that they would not have not have known were present otherwise. In some cases, individuals seem to recognize and seek out specific members of another species. Twenty years of observations on chimpanzees and Western lowland gorillas (<em>Gorilla gorilla gorilla<\/em>) in the Republic of Congo has revealed social ties (some might call them friendships) between individual chimpanzees and gorillas that last for years and occur in a variety of social contexts, including play (Sanz et al. 2022).<\/p>\n<h4 class=\"import-Normal\"><em>Parasite-Host Interactions<\/em><\/h4>\n<p class=\"import-Normal\">Primates are hosts for a variety of <strong>parasites<\/strong>, which are organisms that live in or on another organism (the host). Parasites come in many forms and pose varying levels of danger to the host. Blood parasites cause diseases like yellow fever and malaria. Skin parasites include fleas and ticks, which feed on the host\u2019s blood, and botflies, which lay eggs in the host\u2019s flesh. Bot fly larvae feed on the host\u2019s flesh as they develop and eventually (if not removed) break through the skin at maturity. Gut parasites, like tapeworms, get into the intestines and feed off of the food that is being digested by the host. Because most primates live in groups (see the \u201cPrimate Societies\u201d section of this chapter), the tendency for <strong>social transmission<\/strong> of parasites, or the transfer of parasites from one individual to another, is high. Primates have evolved mechanisms to avoid parasite infection, including switching sleeping and feeding sites so as to avoid parasites. Mandrills (<em>Mandrillus sphinx<\/em>) have been shown to avoid grooming infected conspecifics as well as to avoid their feces, which smell different than the feces of individuals who are not infected with parasites (Poirotte et al. 2017). Other primates, including chimpanzees, appear to self-medicate when infected with parasites by ingesting plants that have antiparasitic properties (Krief et al. 2005).<\/p>\n<h4 class=\"import-Normal\"><em>Human-Primate Interactions<\/em><\/h4>\n<p class=\"import-Normal\">Humans are part of many primate communities and our relationship with our closest relatives is often complicated. In some areas, humans hunt primates for their meat or as trophies, or so they can sell the infants as pets. As the human population increases in size, our demand for natural resources, like wood to build houses or land on which to grow food, also increases, often at the expense of pristine primate (and other animal) habitat. As their natural habitat shrinks, primates search for food in areas occupied by humans and may be shot as crop-raiding pests. While deforestation, hunting, and the pet trade are examples of ways in which humans negatively affect the lives of primates, some human-primate interactions are beneficial. In some parts of the world primates are central to <strong>ecotourism<\/strong>, which focuses on nature-based attractions to educate tourists and uses economically and ecologically sustainable practices. Perhaps one of the greatest success stories of ecotourism involves the mountain gorillas of Rwanda (see Figure 7.4b). After internal conflict plagued Rwanda during the 1990s, the Virunga Mountains area developed gorilla-based tourism to aid in socioeconomic development and to bring stability to the region. This process not only helped to increase mountain gorilla populations but was also able to generate enough income to cover the operation costs of three national parks and provide income and other benefits to people living in the area (Maekawa et al. 2013). You can learn more about human-primate interactions in Appendix B: Primate Conservation.<\/p>\n<h2 class=\"import-Normal\">Primate Societies<\/h2>\n<p class=\"import-Normal\">Unlike many other animals, primates are highly social and many live in stable groups consisting of adult males and females, even outside the<strong> breeding season<\/strong>, when females are <strong>receptive<\/strong> and available for mating because they are not pregnant or nursing. Indeed, <strong>sociality<\/strong>, or the tendency to form social groups, is a key behavioral adaptation of the order primates (see Chapter 5). This has led primatologists to ask two questions: \u201cWhy do primates live in groups?\u201d and \u201cWhat types of groups do primates live in?\u201d<\/p>\n<h3 class=\"import-Normal\"><strong>Why Do Primates Live in Groups?<\/strong><\/h3>\n<p class=\"import-Normal\">Primates live in groups when the benefits of doing so exceed the costs. Although there are many potential benefits to group living, enhanced feeding competition and predator avoidance are important benefits for many group living primates. When primates feed on high-quality, scarce food (like fruit), larger groups are more successful in competition with other groups. For example, in a long-term study of vervets in Kenya\u2019s Amboseli National Park, larger vervet groups had larger and better <strong>home ranges<\/strong>, which is the area in which a group regularly moves around as it performs its daily activities, including searching for food and water. Females in larger groups had higher average infant and female survival rates than the smallest group. Because pregnancy and nursing are energetically expensive for females, female <strong>reproductive success<\/strong>, or genetic contribution to future generations (measured by the number of offspring produced), is limited by access to food. Although living in a group means females compete with members of their own group for food, the benefits of being a member of a larger vervet group outweigh the costs (Cheney and Seyfarth 1987).<\/p>\n<p class=\"import-Normal\">However, because they contain more individuals, larger groups are more likely to attract the attention of predators compared to smaller groups. This is one of the reasons that primates who rely on <strong>crypsis<\/strong>, or the ability to avoid detection by others, including predators, are often <strong>solitary <\/strong>(the term used to describe individuals who do not live together with other members of their species) and <strong>nocturnal<\/strong>, or active at night. If an animal is already hard to see because it is active at night, then moving quietly in small groups is a good strategy to avoid detection by predators. The slow loris (<em>Nycticebus coucang<\/em>) of Southeast Asia is a good example of this strategy (Figure 7.9a). Nocturnal and solitary, the slow loris moves slowly and quietly as its primary strategy to avoid detection (Wiens and Zitzmann 2003). In contrast, primates who live in large groups and are <strong>diurnal<\/strong>, or active during the day (like gelada baboons [<em>Theropithecus gelada<\/em>]; Figure 7.9b) cannot avoid detection by predators. Instead, group-living primates rely on behaviors that alert others to the presence of danger and\/or deter predators, including shared <strong>vigilance<\/strong> (watchful behavior to detect potential danger), <strong>mobbing<\/strong> (the act of cooperatively attacking or harassing a predator), and <strong>alarm calling<\/strong> (vocalizations emitted by social animals in response to danger). We will discuss alarm calls in the Communication section.<\/p>\n<figure id=\"attachment_196\" aria-describedby=\"caption-attachment-196\" style=\"width: 761px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-196\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/6.9.jpg\" alt=\"A slow loris. A group of gelada baboons.\" width=\"761\" height=\"269\" \/><figcaption id=\"caption-attachment-196\" class=\"wp-caption-text\">Figure 7.9a-b: Some primates, like the slow loris (left), are solitary and spend most of their time alone. However, most primates, like the gelada baboon (right), live in groups of varying sizes. Credit: a. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Slow_Loris.jpg\">Slow Loris<\/a> by Jmiksanek is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/legalcode\"> CC BY-SA 3.0 License<\/a>. b. <a href=\"https:\/\/www.flickr.com\/photos\/39997856@N03\/7588490544\">Field of baboons<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/39997856@N03\/\">mariusz kluzniak<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-nd\/2.0\/\">CC BY-NC-ND 2.0 License<\/a>.<\/figcaption><\/figure>\n<h3 class=\"import-Normal\"><strong>What Types of Groups Do Primates Live In? <\/strong><\/h3>\n<p class=\"import-Normal\">Primates vary with regard to the types of groups in which they live. A <strong>social system <\/strong>describes a set of social interactions and behaviors that is typical for a species. The components that make up a species\u2019 social system include:<\/p>\n<ul>\n<li class=\"import-Normal\">Group size, which refers to the number of individuals that typically live together. Primate group size can be highly variable, ranging from one or a few individuals, to a few dozen, upward to several hundred individuals.<\/li>\n<li class=\"import-Normal\">Group composition describes group membership in terms of age class (e.g., adult, juvenile, infant) and sex. In some primates, groups consist of a mother and her dependent offspring while in others, one adult male lives long-term with one adult female and their dependent offspring. In other species, one or more adult males live with multiple females and their offspring.<\/li>\n<li class=\"import-Normal\">A species\u2019 <strong style=\"text-align: initial;text-indent: 18pt;font-size: 1em\">mating system<\/strong><span style=\"text-align: initial;text-indent: 18pt;font-size: 1em\"> refers to which male(s) and female(s) mate. The terms that describe a mating system (e.g., <\/span><strong style=\"text-align: initial;text-indent: 18pt;font-size: 1em\">polygyny<\/strong><span style=\"text-align: initial;text-indent: 18pt;font-size: 1em\">, in which one male mates with multiple females) are sometimes used to describe a primate species\u2019 social system, but a mating system is one component of the species\u2019 social system. For example, two species might both have polygynous mating systems, but in one species, the group is composed of one male and multiple females, while members of the other species live as solitary individuals.<\/span><\/li>\n<li class=\"import-Normal\"><strong style=\"text-align: initial;text-indent: 18pt;font-size: 1em\">Ranging behavior <\/strong><span style=\"text-align: initial;text-indent: 18pt;font-size: 1em\">refers to the way in which animals move about their environment. Most primate species have a home range, where they perform their daily activities. Some primates defend a <\/span><strong style=\"text-align: initial;text-indent: 18pt;font-size: 1em\">territory<\/strong><span style=\"text-align: initial;text-indent: 18pt;font-size: 1em\"> which is the part of the home range that the group actively guards in an attempt to keep out conspecifics.<\/span><\/li>\n<li class=\"import-Normal\"><strong style=\"text-align: initial;text-indent: 18pt;font-size: 1em\">Dispersal <\/strong><span style=\"text-align: initial;text-indent: 18pt;font-size: 1em\">patterns describe which sex moves to a new group to reproduce. In most primate species, males disperse because the benefits of dispersal, including increased access to mates and reduced competition from other males, outweigh the costs of migrating into a new group, which often comes with aggression from current group members. For many female primates, the opposite is true: females usually benefit from remaining <\/span><strong style=\"text-align: initial;text-indent: 18pt;font-size: 1em\">philopatric<\/strong><span style=\"text-align: initial;text-indent: 18pt;font-size: 1em\">, or in the group of their birth. This allows them to maintain strong alliances with female relatives, which helps them compete successfully against other groups for food. In solitary species, offspring of both sexes leave their mother\u2019s home range and become solitary. If this did not happen, the species would not be solitary. Even though both sexes disperse in solitary species, males usually disperse farther than females.<\/span><\/li>\n<li class=\"import-Normal\">Social interactions describe the ways in which individuals interact with members of their own and other groups of conspecifics. <strong style=\"text-align: initial;text-indent: 18pt;font-size: 1em\">Affiliative <\/strong><span style=\"text-align: initial;text-indent: 18pt;font-size: 1em\">(i.e., friendly or nonaggressive) behaviors include <\/span><strong style=\"text-align: initial;text-indent: 18pt;font-size: 1em\">grooming<\/strong><span style=\"text-align: initial;text-indent: 18pt;font-size: 1em\"> (picking through the fur of another individual), playing, or <\/span><strong style=\"text-align: initial;text-indent: 18pt;font-size: 1em\">coalitions <\/strong><span style=\"text-align: initial;text-indent: 18pt;font-size: 1em\">(temporary alliances between individuals). <\/span><strong style=\"text-align: initial;text-indent: 18pt;font-size: 1em\">Agonistic<\/strong><span style=\"text-align: initial;text-indent: 18pt;font-size: 1em\"> (i.e., aggressive) behaviors include fighting over food or fighting over access to mates. In groups that contain multiple adult individuals of the same sex, it is common to have a <\/span><strong style=\"text-align: initial;text-indent: 18pt;font-size: 1em\">dominance hierarchy<\/strong><span style=\"text-align: initial;text-indent: 18pt;font-size: 1em\">, or a group of individuals that can be ranked according to their relative amount of power over others in the hierarchy. Initially, dominance hierarchies are established through the outcome of conflicts. Individuals who lose conflicts with others are <\/span><strong style=\"text-align: initial;text-indent: 18pt;font-size: 1em\">subordinate<\/strong><span style=\"text-align: initial;text-indent: 18pt;font-size: 1em\"> (or low rank) to those who win them. Those who win conflicts are <\/span><strong style=\"text-align: initial;text-indent: 18pt;font-size: 1em\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_219_744\">dominant<\/a> <\/strong><span style=\"text-align: initial;text-indent: 18pt;font-size: 1em\">(or high rank). Dominant individuals gain access to resources, like food or mates, before subordinates. Once a hierarchy is established, agonism decreases because everyone \u201cknows their place.\u201d<\/span><\/li>\n<\/ul>\n<p class=\"import-Normal\">The main types of primate social systems are as follows: solitary; single-male, single-female; single-male, multi-female; multi-male, multi-female; fission-fusion; and multi-male, single-female. These types are discussed below.<\/p>\n<h4 class=\"import-Normal\"><em>Solitary<\/em><\/h4>\n<p class=\"import-Normal\">Recall that the term <em>solitary<\/em> is used to describe species in which individuals do not live or travel together with other members of the same species, except for mothers and unweaned offspring. Males typically occupy a large home range or territory that overlaps the home ranges of multiple females, with whom they mate (Figure 7.10a). Because one male mates with multiple females, the mating system of solitary primates is polygyny. Social interactions between adults are limited but because some males do not get to mate, competition between males is intense. When males compete physically, they benefit from large body size and weaponry. The result is<strong> sexual dimorphism<\/strong>, when males and females look different from one another. Both males and females disperse, although males move farther from their mother than females. The nocturnal West African potto (<em>Perodicticus <\/em><em>potto<\/em>; Figure 7.10b) is solitary. Bornean orangutans, which are diurnal, are also solitary.<\/p>\n<\/div>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_210\" aria-describedby=\"caption-attachment-210\" style=\"width: 620px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-197\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/6.10-01-1.jpg\" alt=\"Grouping pattern description is available in caption. A potto in a tree at night also shown.\" width=\"620\" height=\"272\" \/><figcaption id=\"caption-attachment-210\" class=\"wp-caption-text\">Figure 7.10a-b: Illustration of a solitary species\u2019 grouping pattern is shown on the left. Key: square = adult male; dot = adult female; open circle represents the outline of the male\u2019s home range; open oval represents individual female home ranges. The West African potto is a solitary primate (right). <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. Polygyny in a Solitary Social System original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Karin Enstam Jaffe is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\"> CC BY-NC 4.0 License<\/a>. b. <a href=\"https:\/\/www.flickr.com\/photos\/nikborrow\/31307385633\">West African Potto Perodicticus potto Kakum National Park, Ghana<\/a> by<a href=\"https:\/\/www.flickr.com\/people\/nikborrow\/\"> Nik Barrow<\/a> has been modified (cropped) and is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/2.0\/\"> CC BY-NC 2.0 License<\/a>.<\/figcaption><\/figure>\n<div class=\"__UNKNOWN__\">\n<h4 class=\"import-Normal\"><em>Single-Male, Single-Female<\/em><\/h4>\n<p class=\"import-Normal\">Primate species in which an adult male and adult female live together with their dependent offspring have a <strong>single-male, single-female<\/strong> social system, sometimes referred to as a \u201cfamily,\u201d with group sizes between two and five individuals. The adult male and adult female engage in behaviors that strengthen their social relationship, or <strong>pair bond<\/strong>, including mutual grooming and resting together. The pair defend a territory (Figure 7.11a) and keep same-sex individuals away from their mate. The adult male and adult female mate with each other, so the mating system is <strong>monogamy<\/strong>, although mating outside the pair bond may occur. Species with monogamous mating systems are usually <strong>sexually monomorphic<\/strong> (males and females look similar) because competition for mates is relaxed since most males are able to obtain a mate. Males are usually confident that they are the father of their mate\u2019s infant, so they help with offspring care by carrying the infant when it is not nursing. Once offspring are sexually mature, both males and females disperse. As with solitary species, males disperse farther from their parents than females. Bolivian Gray titi monkeys (<em>Plecturocebus donacophilus<\/em>) are an example of a species that has a single-male, single-female social system. One of their signature behaviors is tail twining, when two individuals sit with their tails wrapped around each other (Figure 7.11b). This behavior reinforces the social bond among family members and is especially common between the adult male and female. Gibbons (<em>Hylobates<\/em>) and owl monkeys (<em>Aotus<\/em>) also live in single-male, single-female groups.<\/p>\n<figure id=\"attachment_198\" aria-describedby=\"caption-attachment-198\" style=\"width: 608px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-198\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/6.11-01.jpg\" alt=\"Left: Circle contains one dot (female) and one square (male). Right: Two titi monkeys.\" width=\"608\" height=\"357\" \/><figcaption id=\"caption-attachment-198\" class=\"wp-caption-text\">Figure 7.11a-b: Illustration of a single-male, single-female grouping pattern is shown on the left. Key: square = adult male; dot = adult female; open circle represents the outline of the group\u2019s territory, which the bonded pair defend against conspecifics. The titi monkey (right) is an example of a primate species with a single-male, single-female social system. Credit: a. Single-Male, Single-Female Social System original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Karin Enstam Jaffe is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\"> CC BY-NC 4.0 License<\/a>. b. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Callicebus-brunneus-London-Zoo.jpg\">Two Red Titi Monkeys (Callicebus cupreus) sitting together with their tails intertwined at the London Zoo<\/a> by<a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Stevenj\"> Steven G. Johnson<\/a> has been modified (cropped) and 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<\/div>\n<div class=\"__UNKNOWN__\">\n<h4 class=\"import-Normal\"><em>Single-Male, Multi-Female<\/em><\/h4>\n<p class=\"import-Normal\"><strong>Single-male, multi-female<\/strong> groups consist of one adult male living with multiple adult females and their dependent offspring (Figure 7.12a ) . These groups can range from as few as five or ten individuals to as many as 50. Female social relationships are governed by the female dominance hierarchy. Females are usually philopatric and males disperse. Males who are unable to join a group of females may join a bachelor group with other males. Because a single male mates with multiple females, the mating system is polygyny. Species that form single-male, multi-female groups may or may not defend a territory, but the <strong>resident male<\/strong>, who lives with a group of females, is aggressive toward other males, who may try to take over the group and become the new resident male. Competition between males to be the resident male of a group is intense, and these species usually display sexual dimorphism, with males being larger than females and possessing large canines. Hanuman langurs (<em>Semnopithecus entellus<\/em>) of India form single-male, multi-female groups (Figure 7.12b). When a new male takes over a group of females and ousts the former resident male, he may commit <strong>infanticide, <\/strong>or kill the unweaned infants. This is especially likely if the new resident male has not yet mated with any of the females and thus cannot be the infants\u2019 father. This causes the females, who were nursing, to become sexually receptive sooner, increasing the new resident male\u2019s chances of producing offspring (Sharma, Ram, and \u200b\u200bRaipurohit 2010). Gorillas, patas monkeys, and golden snub-nosed monkeys (<em>Rhinopithecus roxellana<\/em>) also live in single-male, multi-female groups.<\/p>\n<p>&nbsp;<\/p>\n<\/div>\n<figure id=\"attachment_210\" aria-describedby=\"caption-attachment-210\" style=\"width: 749px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-199\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/6.12.jpg\" alt=\"Left: Circle contains nine dots and one square; outside are three squares. Right: Adult langur and infant.\" width=\"749\" height=\"295\" \/><figcaption id=\"caption-attachment-210\" class=\"wp-caption-text\">Figure 7.12a-b: An illustration of the one-male, multi-female grouping pattern is shown on the left. Key: square = adult male; dot = adult female; open circle represents the outline of the group\u2019s home range (or territory). The Hanuman langur (right) is an example of a species with a one-male, multi-female social system. Credit: a. Single-Male, Multi-Female Social System original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Karin Enstam Jaffe is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\"> CC BY-NC 4.0 License<\/a>. b. <a href=\"https:\/\/www.pexels.com\/photo\/close-up-photo-of-two-gray-langurs-8642891\/\">Close-up of Two Grey Langurs<\/a> by<a href=\"https:\/\/www.pexels.com\/@amitrai10\/\"> Amit Rai<\/a> has been modified (cropped) and is<a href=\"https:\/\/www.pexels.com\/license\/\"> free to use via Pexels<\/a>.<\/figcaption><\/figure>\n<div class=\"__UNKNOWN__\">\n<h4 class=\"import-Normal\"><em>Multi-Male, Multi-Female<\/em><\/h4>\n<p class=\"import-Normal\"><strong>Multi-male, multi-female<\/strong> groups consist of multiple adult males living with multiple adult females and their dependent offspring. Although there is more than one adult male, there are more adult females than adult males in the group (Figure 7.13a). Multi-male, multi-female groups can range in size from about ten to as many as 500 individuals. They occupy a home range but may or may not defend a territory. In groups that contain multiple males and multiple females, it is not possible for one male to monopolize all the matings, so the mating system is <strong>polygamy<\/strong>, in which multiple males mate with multiple females. However, this does not mean that all males have an equal opportunity to mate with all females. In multi-male, multi-female groups, both males and females form a dominance hierarchy. The male dominance hierarchy determines their access to females for mating in much the same way that a female dominance hierarchy determines a female\u2019s access to food. Because their place in the hierarchy can affect their reproductive success, males compete with each other, but because it is rare for males to be excluded from mating altogether, the level of competition and degree of sexual dimorphism are less extreme than what we see in polygynous species. Usually, females are philopatric and males disperse. Vervet monkeys (Figure 7.13b), ring-tailed lemurs (<em>Lemur catta<\/em>), white-faced capuchins (<em>Cebus capucinus<\/em>), and black-capped squirrel monkeys (<em>Saimiri boliviensis<\/em>) live in multi-male, multi-female groups.<\/p>\n<\/div>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_210\" aria-describedby=\"caption-attachment-210\" style=\"width: 585px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-200\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/6.13.jpg\" alt=\"Circle contains twelve dots and three squares. Right: Two vervet monkeys.\" width=\"585\" height=\"267\" \/><figcaption id=\"caption-attachment-210\" class=\"wp-caption-text\">Figure 7.13a-b: An illustration of the multi-male, multi-female grouping pattern is shown on the left. Key: square = adult male; dot = adult female; open circle represents the outline of the group\u2019s home range (or territory). Vervet monkeys (right) are an example of a species that lives in multi-male, multi-female groups. Credit: a. Multi-Male, Multi-Female Social System original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Karin Enstam Jaffe is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\"> CC BY-NC 4.0 License<\/a>. b. <a href=\"https:\/\/www.flickr.com\/photos\/berniedup\/6011902081\/\">Vervet Monkeys (Chlorocebus pygerythrus)<\/a> by<a href=\"https:\/\/www.flickr.com\/people\/65695019@N07\"> Bernard DUPONT<\/a> has been modified (cropped) and is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/deed.en\"> CC BY-SA 2.0 License<\/a>.<\/figcaption><\/figure>\n<div class=\"__UNKNOWN__\">\n<h4 class=\"import-Normal\"><em>Fission-Fusion<\/em><\/h4>\n<p class=\"import-Normal\"><strong>Fission-fusion<\/strong> is a fluid social system in which the size and composition of the social group changes, with groups splitting (fission) or merging (fusion) depending on food availability (Pinacho-Guendulain and Ramos-Fern\u00e1ndez 2017). When key resources are scarce, individuals spread out (fission) and move and feed individually or in small subgroups (Figure 7.14a). When key food resources are plentiful, individuals come together (fusion) and individuals travel and feed as a more cohesive group (Figure 7.14a). Fission-fusion social structure is believed to reduce feeding competition when resources are scarce. Because group composition changes over time, species with fission-fusion social systems are referred to as a community. Communities consist of multiple adult males, multiple adult females, and offspring, and group size varies but typically ranges from ten to a few dozen individuals. Females typically disperse and males are philopatric. Thus, community males are related and display unusual forms of cooperation. The mating system associated with fission-fusion is polygamy. Because males are not excluded from mating, competition for mates is relaxed and sexual dimorphism is moderate (males are slightly larger than females). Geoffroy\u2019s spider monkeys (<em>Ateles geoffroyi<\/em>) (Figure 7.14b) and chimpanzees both have fission-fusion social system.<\/p>\n<\/div>\n<figure id=\"attachment_210\" aria-describedby=\"caption-attachment-210\" style=\"width: 720px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-201\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/6.14.jpg\" alt=\"Diagrams show fission and fusion. Three spider monkeys.\" width=\"720\" height=\"289\" \/><figcaption id=\"caption-attachment-210\" class=\"wp-caption-text\">Figure 7.14a-b: An illustration of the fission-fusion grouping pattern appears on the left. The left illustration represents fission, when females travel and feed independently in individual home ranges within the community boundary. The right illustration represents fusion, when community members form a cohesive group. <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>. Key: square = adult male; dot = adult female; open circle represents the outline of the community boundary. Open ovals represent individual female home ranges when the group fissions. Credits: a. Fission-Fusion Social System original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Karin Enstam Jaffe is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\"> CC BY-NC 4.0 License<\/a>. b. <a href=\"https:\/\/www.flickr.com\/photos\/berniedup\/49562895393\">Geoffry\u2019s Spider Monkeys (Ateles geoffroyi)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/65695019@N07\">Bernard DUPONT<\/a> has been modified (cropped) and is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/deed.en\"> CC BY-SA 2.0 License<\/a>.<\/figcaption><\/figure>\n<div class=\"__UNKNOWN__\">\n<h4 class=\"import-Normal\"><em>Multi-Male, Single-Female<\/em><\/h4>\n<p class=\"import-Normal\">In <strong>multi-male, single-female <\/strong>groups, two or more males live with one breeding female, her dependent offspring, and non-breeding females (Figure 7.15a). This type of social system is found in the <strong>callitrichids<\/strong>, the primate family that includes marmosets (<em>Callithrix<\/em>; Figure 7.15b) and tamarins (<em>Saguinus<\/em>) of Central and South America. Their groups rarely exceed 15 individuals, and each group actively defends their territory from conspecifics. Although more than one adult female may live in the group, the mating system is <strong>polyandry<\/strong> because there is only one breeding female who mates with all of the adult males. This is achieved through <strong>reproductive suppression<\/strong>, which involves the breeding female preventing other females from reproducing through physiological and\/or behavioral means (Digby, Ferrari, and Salzman 2011). This limits the opportunities for other females in the group to become pregnant. Instead, these females, and the males in the group, help raise the breeding female\u2019s offspring. This is referred to as <strong>cooperative breeding<\/strong> and usually takes the form of carrying infants, grooming them, and protecting them from danger (de Oliveira Terceiro and Burkart 2019). Because reproductive opportunities for female tamarins and marmosets are limited, they are very competitive, and females are slightly larger than males, which helps them compete for the breeding spot in a group.<\/p>\n<p>&nbsp;<\/p>\n<\/div>\n<figure id=\"attachment_210\" aria-describedby=\"caption-attachment-210\" style=\"width: 578px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-202\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/6.15.jpg\" alt=\"Circle contains two squares, two unmarked dots, and a B dot. Right: Marmosets with twins.\" width=\"578\" height=\"269\" \/><figcaption id=\"caption-attachment-210\" class=\"wp-caption-text\">Figure 7.15a-b: An illustration of multi-male, single-female grouping pattern appears on the left. Key: square = adult male; B dot = breeding female; unmarked dot = non-breeding female; open circle represents the outline of the group\u2019s territory, which is defended against conspecifics. The common marmoset (Callithrix jacchus) is an example of a primate species that has this type of social system (right). Credit: a. Multi-Male, Single-Female Social System original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Karin Enstam Jaffe is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\"> CC BY-NC 4.0 License<\/a>. b. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Family_of_Common_Marmoset_-_REGUA_-_Brazil_MG_9480_(12930855765).jpg\">Family of Common Marmoset &#8211; REGUA &#8211; Brazil MG 9480 (12930855765)<\/a> by<a href=\"https:\/\/www.flickr.com\/people\/30818542@N04\"> Francesco Veronesi<\/a> has been modified (cropped) 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<div class=\"__UNKNOWN__\">\n<h2 class=\"import-Normal\">Reproductive Strategies<\/h2>\n<p class=\"import-Normal\">Reproductive strategies have evolved to maximize individual reproductive success. These strategies can be divided into those that deal with offspring production and care (parental investment) and those that maximize mating success (sexual selection). Because the reproductive physiology of male and female primates differs, males and females differ with regard to parental investment and sexual selection strategies. Female strategies focus on obtaining the food necessary to sustain a pregnancy and choosing the best male(s) to father offspring. Male strategies focus on gaining access to receptive females.<\/p>\n<h3 class=\"import-Normal\"><strong>Parental Investment<\/strong><\/h3>\n<figure style=\"width: 362px\" class=\"wp-caption alignright\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image9.jpg\" alt=\"Monkey holds baby.\" width=\"362\" height=\"241\" \/><figcaption class=\"wp-caption-text\">Figure 7.16: A female Japanese macaque nursing her infant. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Snow_monkey_baby_milk_time.jpg\">Snow monkey baby milk time<\/a> by Daisuke Tashiro 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>Biologically speaking, <strong>parental investment<\/strong> is any time or energy a parent devotes to the current offspring that enhances its survival (and eventual reproductive success) at the expense of the parent\u2019s ability to invest in the next offspring (Trivers 1972). Female primates invest more heavily in offspring than males. Even before conception, females produce energy-containing eggs, and they will be responsible for sustaining a fertilized egg until it implants in the uterus. After that, they invest in pregnancy and lactation (Figure 7.16). Because all of this investment requires a lot of energy, female primates can only produce one offspring (or litter) at a time. A species\u2019 <strong>interbirth interval<\/strong>, or the typical length of time between one birth and the next, is determined by the length of time necessary to maximize each offspring\u2019s survival without jeopardizing the female\u2019s ability to produce the greatest number of offspring possible. If a female invests too little (i.e., weans an offspring too early), she may give birth to many offspring, but very few (if any) of them will survive. If she invests too much (i.e., nurses an offspring even after it could be weaned), she ensures the survival of that individual offspring but will not be able to produce very many during her lifetime. To maximize her reproductive success, a female must invest <em>just<\/em> long enough to ensure the greatest number of offspring survive to reproduce. We often think of maternal care as an <strong>innate<\/strong> (or natural), instinctive behavior. Yet this is not the case. The \u201cSpecial Topic: Is Maternal Behavior Innate?\u201d dispels the myth that maternal behavior is solely instinctual and explains how female primates learn to be good mothers.<\/p>\n<h3 class=\"import-Normal\"><strong>Sexual Selection<\/strong><\/h3>\n<p class=\"import-Normal\"><strong>Sexual selection<\/strong>, or selection for traits that maximize mating success, comes in two forms. <strong>Intrasexual selection<\/strong> is selection for traits that enhance the ability of members of one sex to compete amongst themselves (\u201c<em>intra<\/em>sexual\u201d = within one sex). <strong>Intersexual selection<\/strong> is selection for traits that enhance the ability of one sex to attract the other (\u201c<em>inter<\/em>sexual\u201d = between the sexes).<\/p>\n<p class=\"import-Normal\">Intrasexual selection most often operates on males. In the wild, adult females are either pregnant or lactating for most of their adult lives. So, in a given population, there are usually more males available and willing to mate than there are females. The result? Females are a scarce resource over which males compete. Intrasexual selection favors traits that help a male win fights with other males. In primates, these traits include large body size (Figure 7.17a) and large canines (Figure 7.17b). Because females don\u2019t possess these same traits, males and females of some species look different; that is, they are sexually dimorphic (Figure 7.17a).<\/p>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_207\" aria-describedby=\"caption-attachment-207\" style=\"width: 691px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-204\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/6.17.jpg\" alt=\"Male baboon with two females. Adult male baboon.\" width=\"691\" height=\"293\" \/><figcaption id=\"caption-attachment-207\" class=\"wp-caption-text\">Figure 7.17a-b: a. Hamadryas baboons (Papio hamadryas) are sexually dimorphic. The male (left) is much bigger than the female (center) and also has different colored fur. b. Adult males, like this gelada baboon, also have larger canines than females. Credit: a. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Dierenpark_Emmen_baboon_(2679944324).jpg\">Dierenpark Emmen baboon (2679944324)<\/a> by<a href=\"https:\/\/www.flickr.com\/people\/80538772@N00\"> robin bos<\/a> has been modified (cropped) and is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/legalcode\"> CC BY 2.0 License.<\/a> b. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Olive_Baboon_Papio_anubis_in_Tanzania_3066_Nevit.jpg\">Olive Baboon Papio anubis, Picture Taken in Tanzania<\/a> by Nevit Dilmen has been modified (cropped) and 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 class=\"import-Normal\">Intersexual selection also tends to operate on males, selecting traits that make a male more attractive to females. Females, in turn, choose among potential fathers. Because female primates invest more in offspring production and care than males (see the \u201cParental Investment\u201d section, above), it is more costly for them if the offspring dies before maturity or reaches maturity but does not reproduce. Thus, it benefits a female primate to be choosy and try to pick the healthiest male as a mate. Males must display traits that tell a female why she should choose <em>him<\/em>, and not another male, as her mate.<\/p>\n<p class=\"import-Normal\">What traits are female primates looking for? In humans, women may look for a mate who can provide important resources, such as food, paternal care, or protection. This is rare in other primates, though, since most females do not need males to provide resources. More commonly, female primates obtain genetic benefits for their offspring from choosing one male over another. Often the specific criteria by which females select mates is unknown. However, if a female chooses a healthy (as indicated by traits like a plush coat, bright coloration, or large body size) or older male, she may obtain genes for her offspring that code for health or long life. If a male\u2019s rank is determined by competitive ability that has a genetic component, females who choose males who win fights may acquire these genes (and qualities) for their offspring. Females in some species appear to prefer new immigrants, sometimes even \u201csneaking\u201d copulations with males who are not established members of their groups. Such a preference may provide their offspring with novel genes and increase genetic variation (for more about the importance of genetic variation, see Chapter 4). Female choice is often more subtle than male-male competition, so it can be more difficult to study. However, as more research is conducted, we continue to improve our understanding of the ways that female primates exert their choice.<\/p>\n<div class=\"textbox\">\n<h2 class=\"import-Normal\">Special Topic: Is Maternal Behavior Innate?<\/h2>\n<p>Zoos almost always have nurseries where infants are cared for by zookeepers if their mothers will not care for them (Figure 7.18). These exhibits are among the most popular because the babies are so cute and so much fun to watch. And the caretaking positions in zoo nurseries are often among the most coveted by zoo personnel for the same reasons. But if maternal behavior is instinctive, why do zoo nurseries even exist? The answer is that in many species, including primates, maternal behavior is not purely instinctual; it is dependent on <strong>social learning<\/strong> (behavior learned by observing and imitating others), as well.<\/p>\n<figure style=\"width: 433px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image13-1.png\" alt=\"Newborn orangutan feeding from a bottle.\" width=\"433\" height=\"336\" \/><figcaption class=\"wp-caption-text\">Figure 7.18: Newborn orangutan at Audubon Zoo being bottle-fed. Credit: <a href=\"https:\/\/newsroom.audubonnatureinstitute.org\/critically-endangered-orangutan-gives-birth-at-audubon-zoo\/\">Newborn orangutan born at Audubon Zoo being bottle fed<\/a> (2022) by<a href=\"https:\/\/audubonnatureinstitute.org\/\"> Audubon Nature Institute<\/a> is used by permission.<\/figcaption><\/figure>\n<p>Captive female primates, including gorillas and chimpanzees, who have not had the opportunity to observe their mother or other females care for infants do not know how to care for their own offspring. Although it is preferred that the primate mother care for her own infant, there are cases when she will not and humans must step in to ensure the offspring survives. When hand-rearing by humans is necessary, the infant is returned to the group as soon as possible in the hopes that it will learn species-typical behavior from its mother and other conspecifics. Observations such as these indicate that maternal behavior is learned, not innate, and that maternal care is critically important to the social and psychological development of young primates.<\/p>\n<\/div>\n<h2 class=\"import-Normal\">Communication<\/h2>\n<p class=\"import-Normal\">In its most basic form, communication occurs when one individual (the sender) emits a signal that conveys information, which is detected by another individual (the receiver). We have discussed several aspects of primate sociality in this chapter, all of which require the communication of information between individuals. But exactly <em>how<\/em> does a female chimpanzee communicate her sexual availability? <em>How<\/em> does a vervet monkey communicate the approach of a leopard or that a python is nearby? <em>How<\/em> do solitary, nocturnal primates, like the slow loris, communicate information about themselves to conspecifics? Primate communication comes in four forms: vocal, visual, olfactory, and tactile. Species vary in their reliance on each.<\/p>\n<h3 class=\"import-Normal\"><strong>Vocal Communication<\/strong><\/h3>\n<p class=\"import-Normal\">Primates use sound to communicate danger or threats, to claim and maintain a territory, or make contact with other group members. Alarm calls are given in response to predators. In some cases, alarm calls are used to alert members of the group to the presence of a predator so they can take evasive action. In other cases, they are directed at the predator itself, signaling that it has been detected. You can learn more about alarm calls as forms of vocal communication in the highlight box in this chapter entitled \u201cDig Deeper: Alarm Calls: Signals to Friends or Foes?.\u201d<\/p>\n<p class=\"import-Normal\">Loud calls are designed to travel great distances and are used in territorial defense by many primate species including indris (<em>Indri indri<\/em>), orangutans, gibbons, and howler monkeys (<em>Alouatta<\/em>). In dense forest, where visual communication can be difficult, loud calls can be useful in signaling to conspecifics that a group or individual occupies a specific area. Howler monkeys are named for their loud calls, or \u201croars,\u201d which can be heard one kilometer or more away (Sch\u00f6n Ybarra 1986). Howler monkey roars may act to maintain distance between neighboring groups or keep extragroup males from entering the home range (Sch\u00f6n Ybarra 1986).<\/p>\n<p class=\"import-Normal\">Other vocalizations are intended to communicate with individuals in one\u2019s own group. These include vocalizations given as part of threat displays or dominance interactions, as well as contact calls that provide information about one\u2019s location to other group members. Chacma baboons (<em>Papio ursinus<\/em>) have a rich repertoire of vocalizations for communicating with other group members (Fischer et al. 2008). Adult males give specific vocalizations during threat displays and physical confrontations. Subordinates \u201cscreech\u201d when retreating from a dominant individual, signaling submission. Since baboons rely on membership in their group for finding food and detecting predators, a baboon separated from his group will vocalize in an attempt to regain contact. Young baboons emit their own contact calls when separated from their mothers.<\/p>\n<h3 class=\"import-Normal\"><strong>Visual Communication<\/strong><\/h3>\n<figure id=\"attachment_207\" aria-describedby=\"caption-attachment-207\" style=\"width: 493px\" class=\"wp-caption alignleft\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-206\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/6.19.jpg\" alt=\"Female baboon with sexual swelling.\u00a0Male and female baboon.\" width=\"493\" height=\"209\" \/><figcaption id=\"caption-attachment-207\" class=\"wp-caption-text\">Figure 7.19a-b: Two female hamadryas baboons. The female on the left has a sexual swelling while the female on the right (in foreground, with infant clinging to her belly) does not. An adult male is behind her. Credit: a. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Sexual_swelling_in_female_Hamadryas_baboon.jpg\">Sexual swelling in female Hamadryas baboon<\/a> by<a href=\"https:\/\/www.flickr.com\/photos\/mamoritai\/\"> Mamoritai<\/a> has been modified (cropped) and is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/legalcode\"> CC BY-SA 2.0 License<\/a>. b. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Hamadryas_baboon_at_Giza_Zoo_by_Hatem_Moushir_36.JPG\">Hamadryas baboon at Giza Zoo by Hatem Moushir 36<\/a> by<a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Hatem_Moushir\"> Hatem Moushir<\/a> has been modified (cropped) and 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><strong>Visual communication<\/strong>, which involves signals that can be seen, is an important component of nonhuman primate behavior, alone or in combination with other forms of communication. <strong>Piloerection<\/strong>, or raising one\u2019s hair or fur, is used in aggressive interactions to make an individual appear larger than it actually is. Female macaques (<em>Macaca<\/em>), baboons (<em>Papio<\/em>), and chimpanzees, signal sexual receptivity through changes in the size, shape, and, often, color of their hindquarters, called a <strong>sexual swelling<\/strong> (Figure 7.19a). The sexual swelling reaches its maximum size at ovulation. When females are not receptive, either because they are pregnant or are nursing, they do not display a sexual swelling (Figure 7.19b). Thus, the presence or absence of a sexual swelling signals a female\u2019s reproductive state.<\/p>\n<p>Monkeys and apes use diverse facial expressions in visual communication. Showing your teeth in a \u201csmile\u201d sends a signal of friendship in humans. Displaying teeth in this way is a sign of anxiety or fear in primates. That male mandrill you see \u201cyawning\u201d at your local zoo is actually displaying his teeth to signal tension or to threaten a rival (Figure 7.20a). In addition to showing their canines, male gelada baboons use \u201clip flips,\u201d in which the gums and teeth are exposed by flipping the upper lip up over the nostrils (Figure 7.20b), and \u201craised eyelids,\u201d in which the pale eyelids are exposed by pulling the scalp back as threatening gestures (Aich, Moos-Heilen, and Zimmerman 1990). Submissive males respond by fleeing or presenting their hindquarters.<\/p>\n<figure id=\"attachment_207\" aria-describedby=\"caption-attachment-207\" style=\"width: 597px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-207\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/6.20-1.jpg\" alt=\"Adult male mandrill and adult male hamadryas baboon yawning.\" width=\"597\" height=\"310\" \/><figcaption id=\"caption-attachment-207\" class=\"wp-caption-text\">Figure 7.20a-b: Males use visual displays to communicate with other males. The male mandrill (left) is yawning to display his canines, and the male gelada baboon (right) enhances the yawn by flipping his upper lip back and raising his eyelids. Credit: a. <a href=\"https:\/\/pxhere.com\/en\/photo\/559944\">Mandrill<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/mathiasappel\/with\/24639723420\/\">Mathias Appel<\/a> has been modified (cropped) and designated to the <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/cc0\/\">public domain (CC0)<\/a>. b.<a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:BabouinGeladaAuReveil.JPG\"> BabouinGeladaAuReveil<\/a> by<a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:BluesyPete\"> BluesyPete<\/a> has been modified (cropped) and 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>\n<div class=\"__UNKNOWN__\">\n<figure id=\"attachment_209\" aria-describedby=\"caption-attachment-209\" style=\"width: 414px\" class=\"wp-caption alignleft\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-208\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/6.22.jpg\" alt=\"A bald uakari. A spider monkey.\" width=\"414\" height=\"154\" \/><figcaption id=\"caption-attachment-209\" class=\"wp-caption-text\">Figure 7.22a-b: Many monkey species have colorful faces, including the bald uakari (Cacajao calvus; left) and the white-bellied spider monkey (Ateles belzebuth) (right). Credit: a. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Uakari.jpg\">Uakari<\/a> by Coada dragos has been modified (cropped) and is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\"> CC BY-SA 4.0 License<\/a>. 6.22b <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Ateles_belzebuth_(White-bellied_spider_monkey)_2.jpg\">Ateles belzebuth (White-bellied spider monkey) 2<\/a> by<a href=\"https:\/\/www.flickr.com\/photos\/ewas-world\/\"> Ewa<\/a> (username: Ewcek65) has been modified (cropped) and 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: 163px\" class=\"wp-caption alignright\"><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image4-3.png\" alt=\"A male mandrill\u2019s face.\" width=\"163\" height=\"246\" \/><figcaption class=\"wp-caption-text\">Figure 7.21: The colorful face of the male mandrill provides information about health and fitness to other mandrills.Credit: <a href=\"https:\/\/www.flickr.com\/photos\/mathiasappel\/24842082402\/\">Mandrill<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/mathiasappel\/with\/24639723420\/\">Mathias Appel<\/a> has been modified (cropped) and designated to the <a href=\"https:\/\/creativecommons.org\/share-your-work\/public-domain\/cc0\/\">public domain (CC0)<\/a>.<\/figcaption><\/figure>\n<p>Primates also communicate through color. In female and male mandrills, facial coloration provides information about an individual\u2019s health, competitive ability, and reproductive state to conspecifics (Figure 7.21; Setchell et al. 2008; Setchell, Wickings, and Knapp 2006). Variation in facial coloration among monkeys of Central and South America ranges from very simple (Figure 7.22a) to complex (Figure 7.22b). Species living with larger numbers of other primate species have evolved more complex facial coloration patterns, suggesting that this trait evolved as a form of <strong>species recognition<\/strong>, or the ability to differentiate conspecifics from members of other species (Santana, Lynch Alfaro, and Alfaro 2012).<\/p>\n<h3 class=\"import-Normal\"><strong>Olfactory Communication<\/strong><\/h3>\n<p class=\"import-Normal\">All primates use scent to communicate. Females secrete chemicals from their <strong>anogenital <\/strong>region (the area of the anus and genitals) that provide males with information about their reproductive state. In some species, like macaques and chimpanzees, this olfactory signal is enhanced by a sexual swelling, as discussed above. <strong>Olfactory communication<\/strong>, or communicating through scent, is particularly important for monkeys of Central and South America, lemurs, and lorises. Male and female common squirrel monkeys (<em>Saimiri sciureus<\/em>) (Figure 7.23a) engage in \u201curine washing,\u201d in which an individual urinates on its hands and feet and then uses them to spread urine all over its body. Urine washing may be used to mark trails for others to follow, to control body temperature, as part of dominance displays, or to communicate reproductive state (Boinski 1992). During aggressive interactions with other males, male ring-tailed lemurs rub their tails with scent from glands on their wrists and chests. They use their \u201cperfumed\u201d tails in aggressive interactions with other males, who may respond by waiving their own scented tail, with physical aggression, or by fleeing (Jolly 1966). Males also waive their tails, saturated in scent, to attract females (Shirasu et al. 2020). Males use scent glands in their wrists to mark territorial boundaries (Figure 7.23b; Mertl-Millhollen 1988).<\/p>\n<\/div>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_210\" aria-describedby=\"caption-attachment-210\" style=\"width: 641px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-210\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/6.23.jpg\" alt=\"A squirrel monkey. A ring-tailed lemur.\" width=\"641\" height=\"332\" \/><figcaption id=\"caption-attachment-210\" class=\"wp-caption-text\">Figure 7.23a-b: Some primates, like the common squirrel monkey (left) and the ring-tailed lemur (right), communicate using scent. Credit: a. <a href=\"https:\/\/www.flickr.com\/photos\/rubund\/6337874822\/\">Saimiri sciureus<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/rubund\/\">Ruben Undheim<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/\">CC BY-SA 2.0 License<\/a>. b. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Lemur_catta_004.jpg\">Lemur catta 004<\/a> by <a href=\"https:\/\/en.wikipedia.org\/wiki\/User:Maky\">Maky<\/a> has been modified (cropped) and 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<div class=\"__UNKNOWN__\">\n<h3 class=\"import-Normal\"><strong>Tactile Communication<\/strong><\/h3>\n<p class=\"import-Normal\"><strong>Tactile communication<\/strong>, or communicating through touch, is very important in all primate species. Physical contact is used to comfort and reassure, is part of courtship and mating, and is used to establish dominance and alliances. Grooming is an important and clearly enjoyable form of tactile communication for all primates (Figure 7.24). Not only does grooming serve to clean the skin and fur, removing parasites and debris, but it is an important affiliative behavior that helps reinforce social bonds, repair relationships, and cement alliances.<\/p>\n<figure style=\"width: 674px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image1-8.png\" alt=\"Four primate species grooming.\" width=\"674\" height=\"478\" \/><figcaption class=\"wp-caption-text\">Figure 7.24: Examples of grooming in Japanese macaques (upper left), tufted capuchins (Sapajus apella) (upper right), gelada baboons (lower left), and black-and-white ruffed lemurs (Varecia variegata; lower right). Credit: Examples of grooming original to Explorations: An Open Invitation to Biological Anthropology (2nd ed.) by Karin Jaffe 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:Yakushima_macaques_grooming_each_other.jpg\">Yakushima macaques grooming each other<\/a> by<a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Grendelkhan\"> Grendelkhan<\/a>, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\">CC BY-SA 4.0 License<\/a>; <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Tufted_capuchin_monkeys_grooming_session_III.jpg\">Tufted capuchin monkeys grooming session III<\/a> by Adrian Soldati, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\">CC BY-SA 4.0 License<\/a>;<a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Baboons_Wunania_012018.jpg\"> Baboons Wunania 012018<\/a> by Kim Toogood, <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/legalcode\">CC BY-SA 4.0 License<\/a>;<a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Black-and-white_ruffed_lemur_03.jpg\"> Black-and-white ruffed lemur 03<\/a> by Mattis2412, <a href=\"https:\/\/creativecommons.org\/publicdomain\/zero\/1.0\/deed.en\">public domain (CC0 1.0)<\/a>].<\/figcaption><\/figure>\n<div class=\"textbox shaded\">\n<h2 class=\"import-Normal\">Dig Deeper: Alarm Calls: Signals to Friends or Foes?<\/h2>\n<p class=\"import-Normal\">Alarm calls are common among group-living primates. They often serve to notify conspecifics of potential danger, as is the case with vervet monkeys. Research has shown that: (1) vervets classify predators based on hunting style; (2) alarm calls convey information to other vervets about that hunting style; and (3) other vervets respond in ways appropriate for evading that type of predator (Seyfarth, Cheney, and Marler 1980a). When a vervet gives a \u201cleopard\u201d alarm call (directed at mammalian carnivores like leopards, Figure 7.25a), monkeys on the ground climb the nearest tree, while monkeys already in trees stay there or climb higher. Since most mammalian carnivores hunt on the ground, getting into, and staying in, a tree is the best option for escape. When the \u201csnake\u201d alarm call is given, vervets stand on their hind legs and look down at the ground (Figure 7.25b). Since snakes are not pursuit predators, locating them quickly so as to avoid them is the best strategy. Lastly, when an \u201ceagle\u201d alarm call is given, vervets look up or run into bushes, both of which are useful responses for avoiding hawks and eagles, which attack from above (Figure 7.25c). Vervets clearly understand the meaning of each type of alarm call, as they respond appropriately even when they do not see the actual predator (Seyfarth, Cheney, and Marler 1980b). Such <strong>semantic communication<\/strong>, which involves the systematic use of signals to refer to objects in the environment, was once believed to be unique to humans. It may be a precursor to the symbolic capacities of human language.<\/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\/image5-1.jpg\" alt=\"Primate in a tree views a leopard.\" width=\"482\" height=\"344\" \/><figcaption class=\"wp-caption-text\">Figure 7.25a<\/figcaption><\/figure>\n<figure style=\"width: 484px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image2-2.jpg\" alt=\"Primate views snake on the ground.\" width=\"484\" height=\"338\" \/><figcaption class=\"wp-caption-text\">Figure 7.25b<\/figcaption><\/figure>\n<figure style=\"width: 481px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image4-2.jpg\" alt=\"Primate on the ground sees bird.\" width=\"481\" height=\"517\" \/><figcaption class=\"wp-caption-text\">Figure 7.25c\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 Figure 7.25a-c: Vervet monkeys respond in different ways to alarm calls for each of their three main predators (leopards, snakes, and eagles) which are appropriate to predator hunting strategies. Credit: Vervet Monkey Alarm Calls by Mary Nelson, original to Explorations: An Open Invitation to Biological Anthropology, 2nd edition, 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\">Research on other African monkeys indicates that some species use alarm calls to signal to the predator that it has been detected. Diana monkeys (<em>Cercopithecus diana<\/em>) give alarm calls to leopards (<em>Panthera pardus<\/em>) but not chimpanzees (Zuberb\u00fchler, No\u00eb, and Seyfarth 1997). Because leopards are stealth predators, they rely on the element of surprise to sneak up on their prey (Figure 7.26a). Alarm calling at leopards appears to tell the leopard that it has been seen and therefore its chance of success will be low. Research shows leopards are more likely to stop hunting after an alarm call has been emitted. Unlike leopards, chimpanzees are pursuit predators and may even use alarm calls to locate potential prey (Figure 7.26b). With such a predator, prey are better off remaining as silent as possible so as not to alert the predator to their location (Zuberb\u00fchler et al. 1999).<\/p>\n<figure id=\"attachment_215\" aria-describedby=\"caption-attachment-215\" style=\"width: 1907px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-215 size-full\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/6.26.jpg\" alt=\"Leopard crouches in grass. Chimpanzee looks up.\" width=\"1907\" height=\"589\" \/><figcaption id=\"caption-attachment-215\" class=\"wp-caption-text\">Figure 7.26a-b: Because leopards (left) and chimpanzees (right) hunt differently, Diana monkeys react differently to them. Credit: a. <a href=\"https:\/\/www.flickr.com\/photos\/thimindu\/5842997328\">Crouching Leopard<\/a> by<a href=\"https:\/\/www.flickr.com\/photos\/thimindu\/\"> Thimindu Goonatillake<\/a> is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/\"> CC BY-SA 2.0 License<\/a>. b. <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Chimpanzee_in_the_wild.jpg\">Chimpanzee in the wild<\/a> by D.G. Kulakov 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\">\n<\/div>\n<h2 class=\"import-Normal\"><span style=\"text-align: initial;font-size: 1em\">The Question of Culture<\/span><\/h2>\n<p class=\"import-Normal\">It may be surprising in a chapter on nonhuman primates to see a discussion of culture. After all, culture is considered by many, including cultural anthropologists, to be a distinguishing characteristic of humans. Indeed, some anthropologists question claims of culture in primates and other animals. Definitions of animal culture focus on specific behaviors that are unique to one population. Anthropological definitions of human culture emphasize shared ideology (e.g., values, morals, beliefs) and symbols, not just behavior. Using this definition, some cultural anthropologists view primates as lacking culture because of the absence of symbolic life (e.g., religion). However, the longer we study primate groups and populations, the more insight we gain into primate behavioral variation. If we define <strong>culture<\/strong> as the transmission of behavior from one generation to the next through social learning, then we must view at least some of the behavioral variation we see in primates as forms of <strong>cultural tradition<\/strong>, or a distinctive pattern of behavior shared by multiple individuals in a social group that persists over time (Whiten 2001).<\/p>\n<h3 class=\"import-Normal\"><strong>Chimpanzee Culture<\/strong><\/h3>\n<p class=\"import-Normal\">Due to both their high level of intelligence and the large number of long-term studies on several different populations, chimpanzees provide the best example of cultural tradition in primates. Chimpanzees express cultural variation in multiple behavioral patterns, ranging from population-specific prey preferences and hunting strategies to tool-use techniques and social behaviors. For example, in Tanzania, chimpanzees fish for termites by stripping twigs and then poking the twigs into termite mounds. The termites react to the \u201cinvasion\u201d by attacking the twig. The chimpanzee pulls the twig out, termites attached, and eats them. In Gambia, they use modified twigs to extract honey from holes in trees. In Fongoli, S\u00e9n\u00e9gal, chimpanzees use sticks as \u201cspears\u201d that they stab into tree cavities to hunt for galagos (Figure 7.27). Multiple chimpanzee populations use a \u201chammer and anvil\u201d to crack open nuts, but the specific techniques differ. Because the cultural traditions are so diverse and unique, if a researcher can observe enough of a chimpanzee\u2019s behavior, it is possible to assign that individual to a specific community, much in the same way a human being can be associated with a specific culture based on his or her behavior (Whiten 2011).<\/p>\n<figure style=\"width: 800px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image3-4.jpg\" alt=\"Chimpanzees hunting galagos by poking them with a stick.\" width=\"800\" height=\"453\" \/><figcaption class=\"wp-caption-text\">Figure 7.27a-d: Tool-assisted hunting by a chimpanzee at Fongoli, S\u00e9n\u00e9gal. An adult male chimpanzee uses a tree branch with a modified end to (a\u2013c) stab into a cavity within a hollow tree branch that houses a galago. He ultimately captures the galago as (d) his adolescent brother looks on. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Pan_troglodytes,_tool_use_in_Senegal.jpg\">Pan troglodytes, tool use in Senegal<\/a> by<a href=\"https:\/\/royalsocietypublishing.org\/content\/2\/4\/140507\"> J. D. Pruetz, P. Bertolani, K. Boyer Ontl, S. Lindshield, M. Shelley, and E. G. Wessling<\/a> is under a<a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/legalcode\"> CC BY 4.0 License<\/a>.<\/figcaption><\/figure>\n<p class=\"import-Normal\">How do chimpanzee cultures develop, and how does cultural transmission occur? Although we do not know for sure how chimpanzee cultural traditions develop initially, it is possible that different groups invent, either accidentally or deliberately, certain behaviors that other individuals copy. <strong>Immigration<\/strong>, or movement of an individual into a new group or community, is an important avenue of cultural transmission in chimpanzees, much as it is between human cultures. Immigrants (typically females) may bring cultural traditions to their new community, which residents observe and learn. Conversely, immigrants may observe and learn a cultural tradition practiced in their new community (Whiten 2011).<\/p>\n<h3 class=\"import-Normal\"><strong>Cultural Transmission in Macaques<\/strong><\/h3>\n<p class=\"import-Normal\">Two monkey species are well-known for behavioral variation that has been called \u201cpre-cultural\u201d by some primatologists: Japanese macaques and tufted capuchins (<em>Sapajus apella<\/em>). The transmission of unique <strong>foraging<\/strong> (the act of searching for food) behaviors through the members of a provisioned group of Japanese macaques on Koshima Island is well known (Matsuzawa 2015). In an effort to keep the monkeys nearby, researchers provided them with piles of sweet potatoes. A juvenile female named Imo spontaneously washed a muddy sweet potato in a stream. This new food-processing technique first spread among other juveniles and then gradually to older individuals. Within 30 years, it had spread across generations, and 46 of 57 monkeys in the group engaged in the behavior. Another example comes from a group living far to the north, in Shiga-Heights, Nagano Prefecture. Researchers used apples to entice Japanese macaques to the area. Within a few years, monkeys visited the area regularly and were observed playing with the water in the hot springs. Soon, they climbed into the hot springs and learned to immerse themselves to keep warm and reduce stress when not foraging (Figure 7.28; Matsuzawa 2018; Takeshita et al. 2018; recall also our discussion of hot spring use as an example of analogous traits at the beginning of this chapter). These examples share several characteristics with human culture, including invention or modification of behavior, transmission of behavior between individuals, and the persistence of the behavior across generations (McGrew 1998).<\/p>\n<figure style=\"width: 477px\" class=\"wp-caption alignleft\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/opentextbooks.concordia.ca\/wp-content\/uploads\/sites\/71\/2025\/07\/image6-4.png\" alt=\"Two monkeys in a hot spring.\" width=\"477\" height=\"292\" \/><figcaption class=\"wp-caption-text\">Figure 7.28: Hot spring use by Japanese macaques is a culturally transmitted behavior. Credit: <a href=\"https:\/\/www.flickr.com\/photos\/peterthoeny\/32160301021\">Oooh, This Feels Sooo Good!<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/peterthoeny\/\">Peter Theony &#8211; Quality HD Photography<\/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<h2 class=\"import-Normal\">Summary<\/h2>\n<p class=\"import-Normal\">Primates are socially complex, extremely intelligent, and highly adaptable. In this chapter we discussed aspects of primate ecology, including how body size and characteristics of food affect what primates eat and how primates interact with other species in their environment. We examined why primates live in groups, the types of groups in which they are found, and the reproductive strategies used by males and females to maximize reproductive success. Like other aspects of their behavior, primate communication is varied and complex, and we discussed how primates communicate using vocal, visual, olfactory, and tactile signals. Finally, we explored the question of culture among nonhuman primates and learned that some species have cultural traditions, distinctive patterns of behavior shared by multiple individuals in a social group that persist over time. Humans and other primates are similar in many ways. Learning about principles of primate ecology and behavior can help us better understand our own behavior and the behaviors of our extinct relatives.<\/p>\n<div class=\"textbox shaded\">\n<h2 class=\"import-Normal\">Review Questions<\/h2>\n<ul>\n<li class=\"import-Normal\">If anthropology is the study of humans, why do some anthropologists study primates?<\/li>\n<li class=\"import-Normal\">How does a primate\u2019s ecology affect their diet and interactions with other organisms?<\/li>\n<li class=\"import-Normal\">Why do primates live in groups and in what types of groups do they live?<\/li>\n<li class=\"import-Normal\">What is parental investment and sexual selection?<\/li>\n<li class=\"import-Normal\">What are some examples of primate communication?<\/li>\n<li class=\"import-Normal\">What is the evidence for cultural traditions in primates and how do primatologists think cultural transmission occurs in primates?<\/li>\n<\/ul>\n<\/div>\n<h2 class=\"import-Normal\">Key Terms<\/h2>\n<p class=\"import-Normal\"><strong>Abundance<\/strong>: How much food is available in a given area.<\/p>\n<p class=\"import-Normal\"><strong>Adaptation<\/strong>: A trait with a function.<\/p>\n<p class=\"import-Normal\"><strong>Affiliative<\/strong>: Nonaggressive social interactions and associations between individuals.<\/p>\n<p class=\"import-Normal\"><strong>Agonistic<\/strong>: Conflict; aggressive interactions between individuals.<\/p>\n<p class=\"import-Normal\"><strong>Alarm calling<\/strong>: Vocalizations emitted by social animals in response to danger.<\/p>\n<p class=\"import-Normal\"><strong>Analogy<\/strong>: A similar trait found in different species that arose independently.<\/p>\n<p class=\"import-Normal\"><strong>Anogenital<\/strong>: Relating to the anus and genitals.<\/p>\n<p class=\"import-Normal\"><strong>Breeding season<\/strong>: The time of year when females are receptive to mating.<\/p>\n<p class=\"import-Normal\"><strong>Callitrichids<\/strong>: The primate family that includes marmosets and tamarins.<\/p>\n<p class=\"import-Normal\"><strong>Carnivores<\/strong>: Organisms whose diet consists primarily of animal tissue.<\/p>\n<p class=\"import-Normal\"><strong>Coalition<\/strong>: A temporary alliance between individuals.<\/p>\n<p class=\"import-Normal\"><strong>Community ecology<\/strong>: The branch of ecology that deals with the relationships and interactions between different organisms that occupy the same habitat.<\/p>\n<p class=\"import-Normal\"><strong>Comparison<\/strong>: An examination of the similarities and differences between two things, such as two primate species.<\/p>\n<p class=\"import-Normal\"><strong>Conspecifics<\/strong>: Members of the same species.<\/p>\n<p class=\"import-Normal\"><strong>Cooperative breeding<\/strong>: When individuals other than the mother and father help raise the offspring.<\/p>\n<p class=\"import-Normal\"><strong>Crypsis<\/strong>: The ability to avoid detection by other organisms, such as predators.<\/p>\n<p class=\"import-Normal\"><strong>Cultural tradition<\/strong>: A distinctive pattern of behavior shared by multiple individuals in a social group, which persists over time and is acquired through social learning.<\/p>\n<p class=\"import-Normal\"><strong>Culture<\/strong>: The transmission of behavior from one generation to the next through observation and imitation.<\/p>\n<p class=\"import-Normal\"><strong>Decolonize<\/strong>: Understanding and highlighting the theory and research of non-Western individuals and perspectives.<\/p>\n<p class=\"import-Normal\"><strong>Descendant<\/strong>: A species that comes after the ancestor species.<\/p>\n<p class=\"import-Normal\"><strong>Direct competition:<\/strong> Competition that involves physical interaction between individuals, such as fighting.<\/p>\n<p class=\"import-Normal\"><strong>Dispersal<\/strong>: To leave one\u2019s group or area. This may or may not involve joining another group.<\/p>\n<p class=\"import-Normal\"><strong>Distribution<\/strong>: How food is spread out.<\/p>\n<p class=\"import-Normal\"><strong>Diurnal<\/strong>: Active during the day.<\/p>\n<p class=\"import-Normal\"><strong>Dominance hierarchy<\/strong>: The ranked organization of individuals established by the outcome of aggressive-submissive interactions.<\/p>\n<p class=\"import-Normal\"><strong>Dominant<\/strong>: Being of high rank.<\/p>\n<p class=\"import-Normal\"><strong>Ecology<\/strong>: The relationship between organisms and their physical surroundings.<\/p>\n<p class=\"import-Normal\"><strong>Ecotourism<\/strong>: A form of tourism that focuses on nature-based attractions to provide learning opportunities and that uses economically and ecologically sustainable practices.<\/p>\n<p class=\"import-Normal\"><strong>Ethology<\/strong>: The study of animal behavior.<\/p>\n<p class=\"import-Normal\"><strong>Fission-fusion<\/strong>: Societies in which group composition is flexible, such as chimpanzee and spider monkey societies. Individuals may break up into smaller feeding groups (fission) and combine into larger groups (fusion).<\/p>\n<p class=\"import-Normal\"><strong>Fitness<\/strong>: An individual\u2019s ability to survive and reproduce relative to other members of the same species.<\/p>\n<p class=\"import-Normal\"><strong>Folivores<\/strong>: Organisms whose diet consists primarily of leaves.<\/p>\n<p class=\"import-Normal\"><strong>Foraging<\/strong>: The act of searching for food.<\/p>\n<p class=\"import-Normal\"><strong>Frugivores<\/strong>: Organisms whose diet consists primarily of fruit.<\/p>\n<p class=\"import-Normal\"><strong>Grooming<\/strong>: Picking through the fur of another individual for cleaning or bonding purposes.<\/p>\n<p class=\"import-Normal\"><strong>Heterospecifics<\/strong>: Members of different species.<\/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>Home range<\/strong>: The area that a group or individual uses over a given period of time (often over a year).<\/p>\n<p class=\"import-Normal\"><strong>Homology<\/strong>: A similar trait found in different species because it was inherited from a common ancestor.<\/p>\n<p class=\"import-Normal\"><strong>Immigration<\/strong>: Movement of an individual into a new group or community.<\/p>\n<p class=\"import-Normal\"><strong>Indirect competition<\/strong>: Competition that does not involve physical interaction between individuals, such as eating food before another individual arrives at the food site.<\/p>\n<p class=\"import-Normal\"><strong>Infanticide<\/strong>: The killing of infants of one\u2019s own species.<\/p>\n<p class=\"import-Normal\"><strong>Innate<\/strong>: Natural; as in behavior that comes naturally.<\/p>\n<p class=\"import-Normal\"><strong>Insectivores<\/strong>: Organisms whose diets consist primarily of insects.<\/p>\n<p class=\"import-Normal\"><strong>Interbirth interval<\/strong>: The typical length of time between one birth and the next for a species.<\/p>\n<p class=\"import-Normal\"><strong>Intersexual selection<\/strong>: The selection for traits that enhance the ability of the members of one sex to attract the attention of the other.<\/p>\n<p class=\"import-Normal\"><strong>Intrasexual selection<\/strong>: Selection for traits that enhance the ability of members of one sex to compete amongst themselves.<\/p>\n<p class=\"import-Normal\"><strong>Mating system<\/strong>: A way of describing which male(s) and female(s) mate.<\/p>\n<p class=\"import-Normal\"><strong>Metabolism<\/strong>: The chemical changes that take place in an organism that turn nutrients into energy.<\/p>\n<p class=\"import-Normal\"><strong>Mobbing<\/strong>: Cooperatively attacking or harassing a predator.<\/p>\n<p class=\"import-Normal\"><strong>Monogamy<\/strong>: A mating system in which one male mates with one female.<\/p>\n<p class=\"import-Normal\"><strong>Multi-male, multi-female<\/strong>: A group that consists of multiple adult males, multiple adult females, and their dependent offspring.<\/p>\n<p class=\"import-Normal\"><strong>Multi-male, single-female<\/strong>: A group that consists of two or more adult males, one breeding female, their dependent offspring, and non-breeding females.<\/p>\n<p class=\"import-Normal\"><strong>Mutualistic\/mutualism<\/strong>: When different species work together, with each benefiting from the interaction.<\/p>\n<p class=\"import-Normal\"><strong>Niche<\/strong>: The role of a species in its environment; how it meets its needs for food, shelter, etc.<\/p>\n<p class=\"import-Normal\"><strong>Nocturnal<\/strong>: Active at night.<\/p>\n<p class=\"import-Normal\"><strong>Olfactory communication<\/strong>: Conveying information through scent.<\/p>\n<p class=\"import-Normal\"><strong>Omnivores<\/strong>: Organisms whose diet consists of plant and animal matter.<\/p>\n<p class=\"import-Normal\"><strong>Pair bond<\/strong>: A strong, long-term relationship between two individuals.<\/p>\n<p class=\"import-Normal\"><strong>Parasite<\/strong>: An organism that lives in or on another organism.<\/p>\n<p class=\"import-Normal\"><strong>Parental investment<\/strong>: Any time or energy a parent devotes to the current offspring that enhances its survival (and eventual reproductive success) at the expense of the parent\u2019s ability to invest in the next offspring.<\/p>\n<p class=\"import-Normal\"><strong>Philopatric<\/strong>: Remaining in the group of one\u2019s birth.<\/p>\n<p class=\"import-Normal\"><strong>Piloerection<\/strong>: Raising one\u2019s hair or fur in an effort to look bigger.<\/p>\n<p class=\"import-Normal\"><strong>Polyandry<\/strong>: A mating system in which multiple males mate with a single breeding female.<\/p>\n<p class=\"import-Normal\"><strong>Polygamy<\/strong>: A mating system in which multiple males mate with multiple females.<\/p>\n<p class=\"import-Normal\"><strong>Polygyny<\/strong>: A mating system in which one male mates with multiple females.<\/p>\n<p class=\"import-Normal\"><strong>Polyspecific association<\/strong>: An association between two or more different species that involves behavioral changes in at least one of them to maintain the association.<\/p>\n<p class=\"import-Normal\"><strong>Primate community<\/strong>: All primate species that occur in an area.<\/p>\n<p class=\"import-Normal\"><strong>Primatologist<\/strong>: A scientist who studies primate behavior and\/or ecology.<\/p>\n<p class=\"import-Normal\"><strong>Primatology<\/strong>: The scientific field that studies primate behavior and\/or ecology.<\/p>\n<p class=\"import-Normal\"><strong>Ranging behavior<\/strong>: Refers to the way in which animals move about their environment.<\/p>\n<p class=\"import-Normal\"><strong>Receptive<\/strong>: A term used to describe females who are ready for sexual reproduction (i.e., not pregnant or nursing).<\/p>\n<p class=\"import-Normal\"><strong>Reproductive success<\/strong>: An individual\u2019s genetic contribution to future generations, often measured through the number of offspring produced.<\/p>\n<p class=\"import-Normal\"><strong>Reproductive suppression<\/strong>: The prevention or inhibition of reproduction of healthy adults.<\/p>\n<p class=\"import-Normal\"><strong>Resident male<\/strong>: Term that describes the male who lives with a group of females.<\/p>\n<p class=\"import-Normal\"><strong>Seed dispersal<\/strong>: The process by which seeds move away from the plant that produced them in preparation for germination and becoming a new plant.<\/p>\n<p class=\"import-Normal\"><strong>Semantic communication<\/strong>: The systematic use of signals to refer to objects in the environment.<\/p>\n<p class=\"import-Normal\"><strong>Sexual dimorphism<\/strong>: When males and females of a species have different morphological traits.<\/p>\n<p class=\"import-Normal\"><strong>Sexual selection<\/strong>: The selection for traits that increase mating success. This occurs via intersexual selection and intrasexual selection.<\/p>\n<p class=\"import-Normal\"><strong>Sexual swelling<\/strong>: Area of the hindquarters that change in size, shape, and often color over the course of a female\u2019s reproductive cycle, reaching maximum size at ovulation. Occurs in many primate species that live in Africa and Asia.<\/p>\n<p class=\"import-Normal\"><strong>Sexually monomorphic<\/strong>: When males and females of a species have similar morphological traits.<\/p>\n<p class=\"import-Normal\"><strong>Single-male, multi-female<\/strong>: A group that consists of one adult male, multiple adult female, and their dependent offspring.<\/p>\n<p class=\"import-Normal\"><strong>Single-male, single-female<\/strong>: A group that consists of one adult male, one adult female, and their dependent offspring.<\/p>\n<p class=\"import-Normal\"><strong>Social learning<\/strong>: The idea that new behaviors can be acquired by observing and imitating others.<\/p>\n<p class=\"import-Normal\"><strong>Social system<\/strong>: A way of describing the typical number of males and females of all age classes that live together.<\/p>\n<p class=\"import-Normal\"><strong>Social transmission<\/strong>: Transfer of something from one individual to another; this can include parasites, information, or cultural traditions.<\/p>\n<p class=\"import-Normal\"><strong>Sociality<\/strong>: The tendency to form social groups.<\/p>\n<p class=\"import-Normal\"><strong>Solitary<\/strong>: Living alone.<\/p>\n<p class=\"import-Normal\"><strong>Species recognition<\/strong>: The ability to differentiate conspecifics from members of other species.<\/p>\n<p class=\"import-Normal\"><strong>Subordinate<\/strong>: Being of low rank.<\/p>\n<p class=\"import-Normal\"><strong>Tactile communication<\/strong>: Conveying information through touch.<\/p>\n<p class=\"import-Normal\"><strong>Territory:<\/strong> A home range whose boundary is defended from intrusion by conspecifics.<\/p>\n<p class=\"import-Normal\"><strong>Vertebrates<\/strong>: The group of animals characterized by an internal spinal column or backbone. This includes fish, amphibians, reptiles, birds, and mammals.<\/p>\n<p class=\"import-Normal\"><strong>Vigilance<\/strong>: Watchful behavior used to detect potential danger, usually in the form of predators or potential competitors.<\/p>\n<p class=\"import-Normal\"><strong>Visual communication<\/strong>: Conveying information through signals that can be seen.<\/p>\n<p class=\"import-Normal\"><strong>Vocal communication<\/strong>: Conveying information through signals that can be heard.<\/p>\n<h2 class=\"import-Normal\">For Further Exploration<\/h2>\n<p class=\"import-Normal\">Goodall, Jane. 1971. <em>In the Shadow of Man<\/em>. Boston: Houghton Mifflin.<\/p>\n<p class=\"import-Normal\">Rowe, Noel, and Marc Myers, eds. 2016. <em>All the World\u2019s Primates. <\/em>Charleston, RI: Pogonias Press.<\/p>\n<p class=\"import-Normal\">Strier, Karen B. 2017. <em>Primate Behavioral Ecology.<\/em> 5th ed. New York: Routledge.<\/p>\n<p class=\"import-Normal\"><a href=\"https:\/\/pin.primate.wisc.edu\/\">Primate Info Net<\/a>\u00a0is an information service of the National Primate Research Center at the University of Wisconsin, Madison. It includes Primate Factsheets, primate news and publications, a list of primate-related jobs, and an international directory of primatology, among other information.<\/p>\n<p class=\"import-Normal\"><a href=\"https:\/\/www.primate-sg.org\/\">Primate Specialist Group<\/a>\u00a0is a collection of scientists and conservationists who work in dozens of African, Asian, and Latin American nations to promote research on primate conservation.<\/p>\n<p class=\"import-Normal\">Short videos of some primate behaviors discussed in this chapter:<\/p>\n<ul>\n<li class=\"import-Normal\">Watch vervet monkeys respond to different types of predators: BBC One. n.d. \u201cVervet Monkey\u2019s Escape Plans &#8211; Talk to the Animals: Episode 2 Preview.\u201d Accessed December 16, 2022. <a class=\"rId10\" href=\"https:\/\/www.youtube.com\/watch?v=q8ZG8Dpc8mM\">https:\/\/www.youtube.com\/watch?v=q8ZG8Dpc8mM. <\/a><\/li>\n<li class=\"import-Normal\">Watch male gelada baboons use the lip flip in competition with other males: Smithsonian Channel, June 9, 2017. \u201cWhy These Vegetarian Monkeys Have Sharp Predator Teeth.\u201d Accessed July 25, 2019. <a class=\"rId11\" href=\"https:\/\/www.youtube.com\/watch?time_continue=145&amp;v=aC6iYj_EBjY\">https:\/\/www.youtube.com\/watch?time_continue=145&amp;v=aC6iYj_EBjY<\/a>.<\/li>\n<li class=\"import-Normal\">Watch (and listen to!) howler monkeys \u201croar\u201d: Science News. N.d. \u201cHear a Male Howler Monkey Roar.\u201d Accessed November 21, 2022. <a class=\"rId12\" href=\"https:\/\/www.youtube.com\/watch?v=PYar0dkZ6v8\">https:\/\/www.youtube.com\/watch?v=PYar0dkZ6v8<\/a>.<\/li>\n<li class=\"import-Normal\">Watch Japanese macaques using natural hot springs: National Geographic. N.d. \u201cMeditative Snow Monkeys Hang Out in Hot Springs.\u201d Accessed July 25, 2019. <a class=\"rId13\" href=\"https:\/\/www.youtube.com\/watch?v=Aat9O85ynsI\">https:\/\/www.youtube.com\/watch?v=Aat9O85ynsI<\/a>.<\/li>\n<li class=\"import-Normal\">Watch chimpanzees make and use tools: National Geographic. n.d. \u201cChimps and Tools.\u201d Accessed July 25, 2019. <a class=\"rId14\" href=\"https:\/\/www.youtube.com\/watch?v=o2TBicMRLtA\">https:\/\/www.youtube.com\/watch?v=o2TBicMRLtA<\/a>.<\/li>\n<\/ul>\n<h2 class=\"import-Normal\">References<\/h2>\n<p class=\"import-Normal\">Aich, H., R. Moos-Heilen, and E. Zimmermann. 1990. \u201cVocalizations of Adult Gelada Baboons (<em>Theropithecus gelada<\/em>): Acoustic Structure and Behavioural Context.\u201d <em>Folia Primatologica<\/em> 55 (3\u20134): 109\u2013132.<\/p>\n<p class=\"import-Normal\">Bell, Sarah A. 2017. \u201cGaldikas, Birute.\u201d In <em>The International Encyclopedia of Primatology, Volume A\u2013G<\/em>, edited by Agust\u00edn Fuentes, 445\u2013446. Malden, MA: John Wiley &amp; Sons.<\/p>\n<p class=\"import-Normal\">Boinski, S. 1992. \u201cOlfactory Communication among Costa Rican Squirrel Monkeys: A Field Study.\u201d <em>Folia Primatologica<\/em> 59 (3): 127\u2013136.<\/p>\n<p class=\"import-Normal\">Cheney, D. L., and R. M. Seyfarth. 1987. \u201cThe Influence of Intergroup Competition on the Survival and Reproduction of Female Vervet Monkeys.\u201d <em>Behavioral Ecology and Sociobiology<\/em> 21 (6): 375\u2013386.<\/p>\n<p class=\"import-Normal\">de Oliveira Terceiro, Francisco Edvaldo, and Judith M. Burkart. 2019. \u201cCooperative Breeding.\u201d In <em>Encyclopedia of Animal Cognition and Behavior<\/em>, edited by Jennifer Vonk and Todd Shackelford, 1\u20136. Edinburg, Scotland: Springer Cham.<\/p>\n<p class=\"import-Normal\">Digby, Leslie J., Stephen F. Ferrari, and Wendy Saltzman. 2011. \u201cCallitrichines: The Role of Competition in Cooperatively Breeding Species.\u201d In <em>Primates in Perspective<\/em>, edited by Christina J. Campbell, August\u00cdn Fuentes, Katherine C. MacKinnon, Simon K. Bearder, and Rebecca M. Stumpf, 91\u201310. 2nd edition. New York: Oxford University Press.<\/p>\n<p class=\"import-Normal\">Fischer, Julia, Kurt Hammerschmidt, Dorothy L. Cheney, and Robert M. Seyfarth. 2008. \u201cAcoustic Features of Female Chacma Baboon Barks.\u201d <em>Ethology<\/em> 107 (1): 33\u201354.<\/p>\n<p class=\"import-Normal\">Jolly, Alison. 1966. <em>Lemur Behavior: A Madagascar Field Study<\/em>. Chicago: University of Chicago Press.<\/p>\n<p class=\"import-Normal\">Krief, Sabrina, Claude Marcel Hladik, and Claudie Haxaire. 2005. \u201cEthnomedicinal and Bioactive Properties of Plants Ingested by Wild Chimpanzees in Uganda.\u201d <em>Journal of Ethnopharmacology<\/em> 110 (1\u20133): 1\u201315.<\/p>\n<p class=\"import-Normal\">Maekawa, Mkio, Annette Lanjouw, Eug\u00e8ne Rutagarama, and Doublas Sharp. 2013. \u201cMountain Gorilla Tourism Generating Wealth and Peace in Post-Conflict Rwanda.\u201d <em>Natural Resources Forum<\/em> 37 (2): 127\u2013137.<\/p>\n<p class=\"import-Normal\">Matsuzawa, Tetsuro. 2015. \u201cSweet-Potato Washing Revisited: 50th Anniversary of the <em>Primates<\/em> Article.\u201d <em>Primates<\/em> 56: 285\u2013287.<\/p>\n<p class=\"import-Normal\">Matsuzawa, Tetsuro. 2018. \u201cHot-Spring Bathing of Wild Monkeys in Shiga-Heights: Origin and Propagation of a Cultural Behavior.\u201d <em>Primates<\/em> 59: 209\u2013213.<\/p>\n<p class=\"import-Normal\">McGrew, W. C. 1998. \u201cCulture in Nonhuman Primates?\u201d <em>Annual Review of Anthropology<\/em> 27: 301\u2013328.<\/p>\n<p class=\"import-Normal\">Mertl-Millhollen, Anne S. 1988. \u201cOlfactory Demarcation of Territorial but Not Home Range Boundaries by <em>Lemur catta<\/em>.\u201d <em>Folia Primatologica<\/em> 50 (3\u20134): 175\u2013187.<\/p>\n<p class=\"import-Normal\">Pinacho-Guendulain, B., and G. Ramos-Fern\u00e1ndez. 2017. \u201cInfluence of Fruit Availability on the Fission-Fusion Dynamics of Spider Monkeys (<em>Ateles geoffroyi<\/em>).\u201d <em>International Journal of Primatology<\/em> 38: 466\u2013484.<\/p>\n<p class=\"import-Normal\">Poirotte, Cl\u00e9mence, Fran\u00e7ois Massol, Ana\u00efs Herbert, Eric Willaume, Pacelle M. Bomo, Peter M. Kappeler, and Marie J. E. Charpentier. 2017. \u201cMandrills Use Olfaction to Socially Avoid Parasitized Conspicifics.\u201d <em>Science Advances<\/em> 3 (4): e160172.<\/p>\n<p class=\"import-Normal\">Rodrigues, Michelle. 2019. \u201cIt\u2019s Time to Stop Lionizing Dian Fossey as a Conservation Hero.\u201d <em>Lady Science<\/em> website, September 20. Accessed December 14, 2022. <a class=\"rId15\" href=\"https:\/\/www.ladyscience.com\/ideas\/time-to-stop-lionizing-dian-fossey-conservation\">https:\/\/www.ladyscience.com\/ideas\/time-to-stop-lionizing-dian-fossey-conservation<\/a>.<\/p>\n<p class=\"import-Normal\">Samuni, Liran, Anna Preis, Tobias Deschner, Catherine Crockford, and Roman M. Wittig. 2018. \u201cReward of Labor Coordination and Hunting Success in Wild Chimpanzees.\u201d <em>Communications Biology<\/em> 1: 138.<\/p>\n<p class=\"import-Normal\">Santana, Sharlene E., Jessica Lynch Alfaro, and Michael E. Alfaro. 2012. \u201cAdaptive Evolution of Facial Colour Patterns in Neotropical Primates.\u201d <em>Proceedings of the Royal Society B: Biological Sciences<\/em> 279 (1736): 2204\u20132211.<\/p>\n<p class=\"import-Normal\">Sanz, Crickette M., David Strait, Crepin Eyana Ayina, Jean Marie Massamba, Thierry Fabrice Ebombi, Severin Ndassoba Kialiema, Delon Ngoteni, et al. 2022. \u201cInterspecific Interactions Between Sympatric Apes.\u201d i<em>Science<\/em> 25 (10): 105059.<\/p>\n<p class=\"import-Normal\">Sch\u00f6n Ybarra, M. A. 1986. \u201cLoud Calls of Adult Male Red Howling Monkeys (<em>Alouatta seniculus<\/em>).\u201d <em>Folia Primatologica<\/em> 47 (4): 204\u2013216.<\/p>\n<p class=\"import-Normal\">Setchell, Joanna M., Tessa Smith, E. Jean Wickings, and Leslie A. Knapp. 2008. \u201cSocial Correlates of Testosterone and Ornamentation in Male Mandrills.\u201d <em>Hormones and Behavior<\/em> 54 (3): 365\u2013372.<\/p>\n<p class=\"import-Normal\">Setchell, Joanna M., E. Jean Wickings, and Leslie A. Knapp. 2006. \u201cSignal Content of Red Facial Coloration in Female Mandrills (<em>Mandrillus sphinx<\/em>).\u201d <em>Proceedings of the Royal Society B: Biological Sciences<\/em><a class=\"rId16\" href=\"https:\/\/paperpile.com\/b\/Gb7Zko\/Lxpl\"> 273 (1599): 2395\u20132400.<\/a><\/p>\n<p class=\"import-Normal\">Seyfarth, R. M., D. L. Cheney, and P. Marler. 1980a. \u201cMonkey Responses to Three Different Alarm Calls: Evidence of Predator Classification and Semantic Communication.\u201d <em>Science<\/em> 210 (4471): 801\u2013803.<\/p>\n<p class=\"import-Normal\">Seyfarth, Robert M., Dorothy L. Cheney, and Peter Marler. 1980b. \u201cVervet Monkey Alarm Calls: Semantic Communication in a Free-Ranging Primate.\u201d <em>Animal Behaviour<\/em> 28 (4): 1070\u20131094.<\/p>\n<p class=\"import-Normal\">Sharma, Goutam, Chan Ram, and Lal Singh Rajpurohit. 2010. \u201cA Case Study of Infantcide After Resident Male Replacement in <em>Semnopithecus entellus<\/em> around Jodhpur (India).\u201d <em>Proceeding of the Zoological Society<\/em> 63 (2): 93\u201398.<\/p>\n<p class=\"import-Normal\">Shirasu, Mika, Satomi Ito, Akihiro Itoigawa, Takashi Hayakawa, Kodzue Kinoshita, Isao Munechika, Hiroo Imai, and Kazushige Touhara. 2020. \u201cKey Male Glandular Odorants Attracting Female Ring-Tailed Lemurs.\u201d <em>Current Biology<\/em> 30 (11): 2131\u20132138.<\/p>\n<p class=\"import-Normal\">Stanford, Craig B. 2017. \u201cGoodall, Jane.\u201d In <em>The International Encyclopedia of Primatology, Volume A\u2013G<\/em>, edited by Agust\u00edn Fuentes, 471\u2013472. Malden, MA: John Wiley &amp; Sons.<\/p>\n<p class=\"import-Normal\">Stewart, Kelly. 2017. \u201cFossey, Dian.\u201d In <em>The International Encyclopedia of Primatology, Volume A\u2013G<\/em>, edited by Agust\u00edn Fuentes, 432\u2013433. Malden, MA: John Wiley &amp; Sons.<\/p>\n<p class=\"import-Normal\">Takeshita, Rafaela S.C., Fred B. Bercovitch, Kodzue Kinoshita, and Michael A. Huffman. 2018. \u201cBeneficial Effect of Hot Spring Bathing on Stress Levels in Japanese Macaques.\u201d <em>Primates<\/em> 59 (3): 215\u2013225.<\/p>\n<p class=\"import-Normal\">Trivers, Robert L. 1972. \u201cParental Investment and Sexual Selection.\u201d In <em>Sexual Selection and the Descent of Man, 1871\u20131971<\/em>, edited by Bernard Campbell, 136\u2013179. Chicago: Aldine.<\/p>\n<p class=\"import-Normal\">Whiten, Andrew. 2011. \u201cThe Scope of Culture in Chimpanzees, Humans and Ancestral Apes.\u201d <em>Philosophical Transactions of the Royal Society of London B: Biological Sciences<\/em> 366 (1567): 997\u20131007.<\/p>\n<p class=\"import-Normal\">Wiens, Frank, and Annette Zitzmann. 2003. \u201cSocial Structure of the Solitary Slow Loris <em>Nycticebus coucang<\/em> (Lorisidae).\u201d <em>Journal of Zoology<\/em> 261 (1): 35\u201346.<\/p>\n<p class=\"import-Normal\">Zuberb\u00fchler, Klaus, David Jenny, and Redouan Bshary. 1999. \u201cThe Predator Deterrence Function of Primate Alarm Calls.\u201d <em>Ethology<\/em> 105 (6): 477\u2013490.<\/p>\n<p class=\"import-Normal\">Zuberb\u00fchler, Klaus, Ronald No\u00eb, and Robert M. Seyfarth. 1997. \u201cDiana Monkey Long-Distance Calls: Messages for Conspecifics and Predators.\u201d <em>Animal Behaviour<\/em> 53 (3): 589\u2013604.<\/p>\n<h2 class=\"import-Normal\">Acknowledgments<\/h2>\n<p class=\"import-Normal\">The author is grateful to the editors for the opportunity to contribute to this open-source textbook. She thanks Dr. Stephanie Etting for her encouragement and support during the revision of this chapter. Her suggestions, along with comments made by two anonymous reviewers on an earlier draft of this chapter, improved the final version considerably. Finally, she thanks all the primatologists who came before her, especially her advisor, Lynne A. Isbell, for their tireless efforts to understand the behavior and ecology of the living primates. Without their work, this chapter would not have been possible.<\/p>\n<\/div>\n<div class=\"glossary\"><span class=\"screen-reader-text\" id=\"definition\">definition<\/span><template id=\"term_219_928\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_219_928\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_219_930\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_219_930\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_219_932\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_219_932\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close 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class=\"glossary__definition\" role=\"dialog\" data-id=\"term_219_1034\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_219_1036\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_219_1036\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_219_1038\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_219_1038\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_219_1040\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_219_1040\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_219_1042\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_219_1042\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_219_1044\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_219_1044\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_219_744\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_219_744\"><div tabindex=\"-1\"><p class=\"import-Normal\" style=\"background-color: transparent;text-align: left;margin-left: 0pt;margin-right: 0pt;text-indent: 0pt\"><span style=\"color: #000000\">Kerryn Warren, Ph.D., Grad Coach International<\/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\">Lindsay Hunter, M.A., University of Iowa<\/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\">Navashni Naidoo, M.Sc., University of Cape Town<\/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\">Silindokuhle Mavuso, M.Sc., University of Witwatersrand<\/span><\/p>\n<h6>Student contributors to this chapter: Angela Durastanti, Bryce Muller, Gabriel Barr, Maisie Babbington-Bolduc<\/h6>\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\/chapter-9-early-hominins-2\/\"><em>Chapter 9: Early Hominins<\/em><\/a><em>\" <\/em><em>by Kerryn Warren, K. Lindsay Hunter, Navashni Naidoo, Silindokuhle Mavuso, Kimberleigh Tommy, Rosa Moll, and Nomawethu Hlazo<\/em><em>. 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\"><span style=\"color: #000000\">Learning Objectives<br \/>\n<\/span><\/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>bipedalism<\/strong> (or habitually walking upright on two feet) is where that line would be. <strong>Hominin<\/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>last common ancestor (LCA)<\/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>fossils<\/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>paleoanthropologists<\/strong> (people who study human evolution) speculated about which human traits came first. These included the evolution of a big brain (<strong>encephalization<\/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>morphology<\/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 <strong>East African Rift System <\/strong>(<strong>EARS)<\/strong>; that is, in Ethiopia, Kenya, Tanzania, and Malawi; see Figure 9.1), 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 9.1: 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\/\">IMG_1696 Great Rift Valley<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/ninara\/\">Ninara<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/\">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>site<\/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, <strong>taxonom<\/strong><strong>y<\/strong> was primarily based on morphology. Today it is tied to known relationships based on molecular <strong>phylogeny<\/strong> (e.g., based on DNA) or a combination of the two. This is complicated when applied to living <strong>taxa<\/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>cladistics <\/strong>and <strong>phylogenetics<\/strong><strong>. <\/strong>Cladistics groups organisms according to their last common ancestors based on shared <strong>derived traits<\/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>clade <\/strong>(Figure 9.2). 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 9.2: 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\/\">Clades (Figure 9.2)<\/a> original to <a href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> by Katie Nelson is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">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>lumpers<\/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>splitters<\/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>polytypic<\/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 9.3: 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\/\">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>chronospecies<\/strong> (Figure 9.3). 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\u00a0hominin 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\">fauna<\/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>paleoenvironment<\/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>faunal assemblages <\/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>isotopes<\/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 9.4). 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>flora<\/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 9.4: 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\/\">CO\u2082 increase since the Industrial Revolution<\/a> by <a href=\"https:\/\/www.nasa.gov\/\">NASA<\/a> is in the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Public_domain\">public domain<\/a> and is used within <a href=\"https:\/\/www.nasa.gov\/multimedia\/guidelines\/index.html\">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\/\">\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>arboreal<\/strong>  lifestyle (one living in trees) to a terrestrial one where bipedalism was a more efficient form of locomotion (Figure 9.5). 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>Aridity Hypothesis<\/strong>. This hypothesis states that the long-term <strong>aridification<\/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 9.5: 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\">African savannah @ Masai Mara (21308330314)<\/a> by <a href=\"https:\/\/www.flickr.com\/people\/132394214@N04\">Leo Li<\/a> is under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/legalcode\">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>ungulates<\/strong> (hoofed mammals of various kinds) that had generalized diets fared better than those with specialized diets (Vrba 1988, 1998). <strong>Specialist<\/strong> eaters faced extinction at greater rates than their <strong>generalist <\/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>faunal turnover<\/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> Quaternary Ice Age<\/strong>, between 2.5 mya and 3 mya, brought extreme global, cyclical <strong>interglacial<\/strong>  and <strong>glacial<\/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 behavioral 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 behavioral 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>obligate bipedalism<\/strong>, is important in distinguishing our species from the <strong>extant<\/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 center 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 9.6: 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\">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\">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 9.6). 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 behaviors. These adaptations occur throughout the skeleton and are summarized in Figure 9.7.<\/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 <strong>postcranium<\/strong> and are outlined in Figure 9.7. 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 center 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>mosaic evolution<\/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>hallux<\/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<div align=\"left\">\n<table class=\"grid\">\n<caption>\n<p class=\"import-Normal\" style=\"text-align: left\"><span style=\"color: #000000\">Figure 9.7: Skeletal comparisons between modern humans (obligate bipeds) and nonobligate bipeds (e.g., chimpanzees). Credit: <a class=\"rId34\" style=\"color: #000000\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/chapter-9-early-hominins-2\/\">Skeletal comparisons between modern humans and <\/a><a class=\"rId35\" style=\"color: #000000\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/chapter-9-early-hominins-2\/\">nonobligate<\/a><a class=\"rId36\" style=\"color: #000000\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/chapter\/chapter-9-early-hominins-2\/\"> bipeds (Figure 9.6)<\/a> original to <a class=\"rId37\" style=\"color: #000000\" href=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/explorationsbioanth\/\">Explorations: An Open Invitation to Biological Anthropology<\/a> is under a <a class=\"rId38\" style=\"color: #000000\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>.<\/span><\/p>\n<\/caption>\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 center 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\">https:\/\/pixabay.com\/photos\/snake-adder-serpent-reptile-animal-2319873\/<\/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\u00a0 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\">https:\/\/commons.wikimedia.org\/w\/index.php?search=snake+in+ancient+egypt&amp;title=Special%3AMediaSearch&amp;type=image<\/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 behaviors toward threats like snakes. This blend of instinct and cultural influence is not only seen in behavior 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 behaviors 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 behavior.<\/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 9.8; 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 9.8: 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\">Sahelanthropus tchadensis: TM 266-01-060-1 anterior 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:\/\/efossils.org\/page\/boneviewer\/Sahelanthropus%20tchadensis\/TM%20266-01-060-1\">Sahelanthropus tchadensis: TM 266-01-060-1 posterior 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:\/\/efossils.org\/page\/boneviewer\/Sahelanthropus%20tchadensis\/TM%20266-01-060-1\">Sahelanthropus tchadensis: TM 266-01-060-1 inferior 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>; and d <a href=\"https:\/\/efossils.org\/page\/boneviewer\/Sahelanthropus%20tchadensis\/TM%20266-01-060-1\">Sahelanthropus tchadensis: TM 266-01-060-1 lateral left 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>.<\/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 behaviors (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>cheek teeth<\/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>Pliocene<\/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 9.9). 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\" aria-describedby=\"caption-attachment-304\" 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\" class=\"wp-caption-text\">Figure 9.9a 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\">Ardipithecus ramidus Skull<\/a> by <a class=\"rId62\" href=\"https:\/\/boneclones.com\/\">\u00a9BoneClones<\/a> is used by permission and available here under a <a class=\"rId63\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC 4.0 License<\/a>; b. <a class=\"rId64\" href=\"https:\/\/boneclones.com\/product\/ardipithecus-ramidus-skull-BH-039\">Artist\u2019s rendition of \u201cArdi\u201d skeleton<\/a> by <a class=\"rId65\" href=\"https:\/\/boneclones.com\/\">\u00a9BoneClones<\/a> is used by permission and available here 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\"><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>frugivorous<\/strong> (fruit-eating) chimpanzee or the <strong>folivorous<\/strong> (foliage-eating) gorilla, as discussed in Chapter 5.<\/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>orthognathic, <\/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>dental formula<\/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>incisors<\/strong>; the pointy <strong>canines<\/strong>; the small, flatter <strong>premolars<\/strong>; and the larger hind <strong>molars<\/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 9.10: 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\">Adult human teeth<\/a> by <a href=\"https:\/\/www.genusfotografen.se\/\">Genusfotografen<\/a> (Tomas Gunnarsson) through <a href=\"https:\/\/wikimedia.se\/\">Wikimedia Sverige<\/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><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>occlude <\/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>procumbent<\/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>incisiform<\/strong> (Figure 9.10). 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.\u00a0In <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>diastema:<\/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>honing P3<\/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>parabolic<\/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>enamel<\/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>cusps,<\/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 behaviors 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>holotype<\/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 9.11). 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\" aria-describedby=\"caption-attachment-304\" 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\" class=\"wp-caption-text\">Figure 9.11: 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\"><em>Kenyanthropus platyops<\/em><\/a><a class=\"rId77\" href=\"https:\/\/efossils.org\/page\/boneviewer\/Kenyanthropus%20platyops\/KNM%20WT%2040000\"> 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\/\">CC BY-NC-SA 2.0 License<\/a> and is <a class=\"rId80\" href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\">used as outlined by eFossils<\/a>; b. <a class=\"rId81\" href=\"https:\/\/efossils.org\/page\/boneviewer\/Kenyanthropus%20platyops\/KNM%20WT%2040000\"><em>Kenyanthropus platyops<\/em><\/a><a class=\"rId82\" href=\"https:\/\/efossils.org\/page\/boneviewer\/Kenyanthropus%20platyops\/KNM%20WT%2040000\"> KNM WT 40000 superior view<\/a> by \u00a9<a class=\"rId83\" href=\"https:\/\/www.efossils.org\/\">eFossils<\/a> is under a <a class=\"rId84\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\">CC BY-NC-SA 2.0 License<\/a> and is <a class=\"rId85\" href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\">used as outlined by eFossils<\/a>; c. <a class=\"rId86\" href=\"https:\/\/efossils.org\/page\/boneviewer\/Kenyanthropus%20platyops\/KNM%20WT%2040000\"><em>Kenyanthropus platyops<\/em><\/a><a class=\"rId87\" href=\"https:\/\/efossils.org\/page\/boneviewer\/Kenyanthropus%20platyops\/KNM%20WT%2040000\"> KNM WT 40000 lateral left view<\/a> by \u00a9<a class=\"rId88\" href=\"https:\/\/www.efossils.org\/\">eFossils<\/a> is under a <a class=\"rId89\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\">CC BY-NC-SA 2.0 License<\/a> and is <a class=\"rId90\" href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\">used as outlined by eFossils<\/a>; d. <a class=\"rId91\" href=\"https:\/\/efossils.org\/page\/boneviewer\/Kenyanthropus%20platyops\/KNM%20WT%2040000\"><em>Kenyanthropus platyops<\/em><\/a><a class=\"rId92\" href=\"https:\/\/efossils.org\/page\/boneviewer\/Kenyanthropus%20platyops\/KNM%20WT%2040000\"> KNM WT 40000 inferior view<\/a> by \u00a9<a class=\"rId93\" href=\"https:\/\/www.efossils.org\/\">eFossils<\/a> is under a <a class=\"rId94\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\">CC BY-NC-SA 2.0 License<\/a> and is <a class=\"rId95\" href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\">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 9.12: 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\">Paranthropus boisei skull<\/a> by Durova 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 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 9.12).<\/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>gracile <\/strong>australopithecines\u201d because of their smaller and less robust features compared to the divergent \u201c<strong>robust<\/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>volcanic tufts<\/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 7). This means that it is possible to know a relatively refined date for any fossil if the <strong>context<\/strong> \u00a0 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 9.13: 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\">Australopithecus anamensis: KNM-KP 29281 occlusal 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>.<\/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 9.13). 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 9.14). 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 7; Hay and Leakey 1982; Leakey and Hay 1979) have drawn much attention.<\/span><\/p>\n<figure id=\"attachment_304\" aria-describedby=\"caption-attachment-304\" 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\" class=\"wp-caption-text\">Figure 9.14 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\">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\/\">the Smithsonian<\/a> [exhibit: \u201cReconstructed Faces: What Does It Mean to Be Human?\u201d] is <a class=\"rId108\" href=\"https:\/\/www.si.edu\/termsofuse\/\">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\">Australopithecus afarensis, adult male. Reconstruction based on <\/a><a class=\"rId110\" href=\"https:\/\/humanorigins.si.edu\/multimedia\/slideshows\/reconstructed-faces\">AL444-2<\/a><a class=\"rId111\" href=\"https:\/\/humanorigins.si.edu\/multimedia\/slideshows\/reconstructed-faces\"> by John Gurche<\/a> by <a class=\"rId112\" href=\"https:\/\/www.si.edu\/\">the Smithsonian<\/a> [exhibit: \u201cReconstructed Faces: What Does It Mean to Be Human?\u201d] is <a class=\"rId113\" href=\"https:\/\/www.si.edu\/termsofuse\/\">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 9.15: 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\">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\">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>prognathic<\/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 9.15). Further evidence of bipedalism is seen in the Laetoli Footprints, which are associated with <em data-start=\"92\" data-end=\"107\">Au. afarensis<\/em> (Chapter 7).\u00a0<\/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>relative dating<\/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 9.16). 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 9.16: An artistic reconstruction of Australopithecus africanus by John Gurche. Credit: <a href=\"https:\/\/humanorigins.si.edu\/multimedia\/slideshows\/reconstructed-faces\">Australopithecus africanus. Reconstruction based on STS 5 by John Gurche <\/a>by <a href=\"https:\/\/www.si.edu\/\">the Smithsonian<\/a> [exhibit: \u201cReconstructed Faces: What Does It Mean to Be Human?] is <a href=\"https:\/\/www.si.edu\/termsofuse\/\">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 9.17). 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\" aria-describedby=\"caption-attachment-304\" 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\" class=\"wp-caption-text\">Figure 9.17: 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\">Australopithecus africanus Sts 5 anterior 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:\/\/efossils.org\/page\/boneviewer\/Australopithecus%20africanus\/Sts%205\">Australopithecus africanus Sts 5 posterior 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:\/\/efossils.org\/page\/boneviewer\/Australopithecus%20africanus\/Sts%205\">Australopithecus africanus Sts 5 superior 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>; and d. <a href=\"https:\/\/efossils.org\/page\/boneviewer\/Australopithecus%20africanus\/Sts%205\">Australopithecus africanus Sts 5 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>.<\/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 9.18; 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 9.18: Australopithecus sediba shows mosaic features between Au. africanus and Homo. Credit: <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Australopithecus_sediba.JPG\">Australopithecus sediba<\/a>, photo by Brett Eloff courtesy <a href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Profberger\">Profberger<\/a> and <a href=\"https:\/\/en.wikipedia.org\/wiki\/University_of_the_Witwatersrand\">Wits University<\/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\" 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>fallback <\/strong><strong>foods<\/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>monophyletic<\/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 9.19; 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\" aria-describedby=\"caption-attachment-304\" 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\" class=\"wp-caption-text\">Figure 9.19: 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\"><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\/\">eFossils<\/a> is under a <a class=\"rId159\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\">CC BY-NC-SA 2.0 License<\/a> and is <a class=\"rId160\" href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\">used as outlined by eFossils<\/a>; b. <a class=\"rId161\" href=\"https:\/\/efossils.org\/page\/boneviewer\/paranthropus%20aethiopicus\/KNM-WT%2017000\"><em>Paranthropus aethiopicus<\/em><\/a><a class=\"rId162\" href=\"https:\/\/efossils.org\/page\/boneviewer\/paranthropus%20aethiopicus\/KNM-WT%2017000\">: KNM-WT 17000 lateral right view<\/a> by \u00a9<a class=\"rId163\" href=\"https:\/\/www.efossils.org\/\">eFossils<\/a> is under a <a class=\"rId164\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\">CC BY-NC-SA 2.0 License<\/a> and is <a class=\"rId165\" href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\">used as outlined by eFossils<\/a>; c. <a class=\"rId166\" href=\"https:\/\/efossils.org\/page\/boneviewer\/paranthropus%20aethiopicus\/KNM-WT%2017000\"><em>Paranthropus aethiopicus<\/em><\/a><a class=\"rId167\" href=\"https:\/\/efossils.org\/page\/boneviewer\/paranthropus%20aethiopicus\/KNM-WT%2017000\">: KNM-WT 17000 superior view<\/a> by \u00a9<a class=\"rId168\" href=\"https:\/\/www.efossils.org\/\">eFossils<\/a> is under a <a class=\"rId169\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\">CC BY-NC-SA 2.0 License<\/a> and is <a class=\"rId170\" href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\">used as outlined by eFossils<\/a>; d. <a class=\"rId171\" href=\"https:\/\/efossils.org\/page\/boneviewer\/paranthropus%20aethiopicus\/KNM-WT%2017000\"><em>Paranthropus aethiopicus<\/em><\/a><a class=\"rId172\" href=\"https:\/\/efossils.org\/page\/boneviewer\/paranthropus%20aethiopicus\/KNM-WT%2017000\">: KNM-WT 17000 posterior view<\/a> by \u00a9<a class=\"rId173\" href=\"https:\/\/www.efossils.org\/\">eFossils<\/a> is under a <a class=\"rId174\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\">CC BY-NC-SA 2.0 License<\/a> and is <a class=\"rId175\" href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\">used as outlined by eFossils<\/a>; e. <a class=\"rId176\" href=\"https:\/\/efossils.org\/page\/boneviewer\/paranthropus%20aethiopicus\/KNM-WT%2017000\"><em>Paranthropus aethiopicus<\/em><\/a><a class=\"rId177\" href=\"https:\/\/efossils.org\/page\/boneviewer\/paranthropus%20aethiopicus\/KNM-WT%2017000\">: KNM-WT 17000 inferior view<\/a> by \u00a9<a class=\"rId178\" href=\"https:\/\/www.efossils.org\/\">eFossils<\/a> is under a <a class=\"rId179\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\">CC BY-NC-SA 2.0 License<\/a> and is <a class=\"rId180\" href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\">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 9.20 and 9.21; 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>hypodigm<\/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>hyper-robust<\/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 9.20: Artistic reconstruction of a Paranthropus boisei, male, by John Gurche. Credit: <a href=\"https:\/\/humanorigins.si.edu\/multimedia\/slideshows\/reconstructed-faces\">Paranthropus boisei, male. Reconstruction based on OH 5 and KNM-ER 406 by John Gurche<\/a> by <a href=\"https:\/\/www.si.edu\/\">the Smithsonian<\/a> [exhibit: \u201cReconstructed Faces: What Does It Mean to Be Human?\u201d] is <a href=\"https:\/\/www.si.edu\/termsofuse\/\">copyrighted and used for educational and noncommercial purposes as outlined by the Smithsonian<\/a>.<\/figcaption><\/figure>\n<figure id=\"attachment_304\" aria-describedby=\"caption-attachment-304\" 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\" class=\"wp-caption-text\">Figure 9.21: \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\">Paranthropus boisei: OH 5 anterior 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:\/\/efossils.org\/page\/boneviewer\/Paranthropus%20boisei\/OH%205\">Paranthropus boisei: OH 5 inferior 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:\/\/efossils.org\/page\/boneviewer\/Paranthropus%20boisei\/OH%205\">Paranthropus boisei: OH 5 posterior 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>.<\/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 9.22; 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\" aria-describedby=\"caption-attachment-304\" 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\" class=\"wp-caption-text\">Figure 9.22: 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\"><em>Paranthropus robustus<\/em><\/a><a class=\"rId209\" href=\"https:\/\/efossils.org\/page\/boneviewer\/Paranthropus%20robustus\/SK%2048\">: SK 48 anterior view<\/a> by \u00a9<a class=\"rId210\" href=\"https:\/\/www.efossils.org\/\">eFossils<\/a> is under a <a class=\"rId211\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\">CC BY-NC-SA 2.0 License<\/a> and is <a class=\"rId212\" href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\">used as outlined by eFossils<\/a>; b. <a class=\"rId213\" href=\"https:\/\/efossils.org\/page\/boneviewer\/Paranthropus%20robustus\/SK%2048\"><em>Paranthropus robustus<\/em><\/a><a class=\"rId214\" href=\"https:\/\/efossils.org\/page\/boneviewer\/Paranthropus%20robustus\/SK%2048\">: SK 48 superior view<\/a> by \u00a9<a class=\"rId215\" href=\"https:\/\/www.efossils.org\/\">eFossils<\/a> is under a <a class=\"rId216\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\">CC BY-NC-SA 2.0 License<\/a> and is <a class=\"rId217\" href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\">used as outlined by eFossils<\/a>; c. <a class=\"rId218\" href=\"https:\/\/efossils.org\/page\/boneviewer\/Paranthropus%20robustus\/SK%2048\"><em>Paranthropus robustus<\/em><\/a><a class=\"rId219\" href=\"https:\/\/efossils.org\/page\/boneviewer\/Paranthropus%20robustus\/SK%2048\">: SK 48 inferior view<\/a> by \u00a9<a class=\"rId220\" href=\"https:\/\/www.efossils.org\/\">eFossils<\/a> is under a <a class=\"rId221\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\">CC BY-NC-SA 2.0 License<\/a> and is <a class=\"rId222\" href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\">used as outlined by eFossils<\/a>; d. <a class=\"rId223\" href=\"https:\/\/efossils.org\/page\/boneviewer\/Paranthropus%20robustus\/SK%2048\"><em>Paranthropus robustus<\/em><\/a><a class=\"rId224\" href=\"https:\/\/efossils.org\/page\/boneviewer\/Paranthropus%20robustus\/SK%2048\">: SK 48 lateral left view<\/a> by \u00a9<a class=\"rId225\" href=\"https:\/\/www.efossils.org\/\">eFossils<\/a> is under a <a class=\"rId226\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\">CC BY-NC-SA 2.0 License<\/a> and is <a class=\"rId227\" href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\">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 9.23: 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\"><em>ustralopithecus africanus<\/em><\/a><a class=\"rId231\" href=\"https:\/\/efossils.org\/page\/boneviewer\/Australopithecus%20africanus\/Taung%201\">: Taung 1 anterior view<\/a> by \u00a9<a class=\"rId232\" href=\"https:\/\/www.efossils.org\/\">eFossils<\/a> is under a <a class=\"rId233\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\">CC BY-NC-SA 2.0 License<\/a> and is <a class=\"rId234\" href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\">used as outlined by eFossils<\/a>; b. <a class=\"rId235\" href=\"https:\/\/efossils.org\/page\/boneviewer\/Australopithecus%20africanus\/Taung%201\"><em>australopithecus africanus<\/em><\/a><a class=\"rId236\" href=\"https:\/\/efossils.org\/page\/boneviewer\/Australopithecus%20africanus\/Taung%201\">: Taung 1 lateral right view<\/a> by \u00a9<a class=\"rId237\" href=\"https:\/\/www.efossils.org\/\">eFossils<\/a> is under a <a class=\"rId238\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/2.0\/\">CC BY-NC-SA 2.0 License<\/a> and is <a class=\"rId239\" href=\"https:\/\/efossils.org\/page\/frequently-asked-questions\">used as outlined by eFossils<\/a>.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\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 9.23; 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>Early Stone Age (ESA)<\/strong> marks the beginning of recognizable technology made by our human ancestors. Stone-tool (or <strong>lithic<\/strong>) technology is defined by the fracturing of rocks and the manufacture of tools through a process called  <strong>knapping<\/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>techno-complex<\/strong>, a term encompassing multiple <strong>assemblages<\/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>knappers<\/strong>) began to change the ways they detached <strong>flakes<\/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>Large Cutting Tools (LCTs)<\/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 9.24: 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\">Olduwan Industry Chopper 2<\/a> by Emmyanne29 is under a <a href=\"https:\/\/creativecommons.org\/publicdomain\/zero\/1.0\/legalcode\">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>Oldowan<\/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 9.24).<\/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 class=\"import-Normal\" style=\"background-color: #ffffff;color: #ffffff\"><span style=\"color: #000000\">Summary<\/span><\/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\" 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 meters tall and females at 1.24 meters.<\/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 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 center 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\">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\">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\">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\">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\/\">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.\">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\/\">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 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. Wynn. 2006. \u201cA Juvenile Early Hominin Skeleton from Dikika, Ethiopia.\u201d <em>Nature<\/em> 443 (7109): 296\u2013301.<\/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\">Asfaw, Berhane, Tim White, Owen Lovejoy, Bruce Latimer, Scott Simpson, and Gen Suwa. 1999. \u201c<em>Australopithecus garhi<\/em>: A New Species of Early Hominid from Ethiopia.\u201d <em>Science<\/em> 284 (5414): 629\u2013635.<\/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\">Behrensmeyer, Anna K., Nancy E. Todd, Richard Potts, and Geraldine E. McBrinn. 1997. \u201cLate Pliocene Faunal Turnover in the Turkana Basin, Kenya, and Ethiopia.\u201d <em>Science<\/em> 278 (5343): 637\u2013640.<\/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\">Berger, Lee R., Darryl J. De Ruiter, Steven E. Churchill, Peter Schmid, Kristian J. Carlson, Paul HGM Dirks, and Job M. Kibii. 2010. \u201c<em>Australopithecus sediba<\/em>: A New Species of <em>Homo<\/em>-like Australopith from South Africa.\u201d <em>Science<\/em> 328 (5975): 195\u2013204.<\/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\">Bobe, Ren\u00e9, and Anna K. 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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>\u00a012 (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). Pulvinar neurons reveal neurobiological evidence of past selection for rapid detection of snakes. <em>Proceedings of the National Academy of Sciences, 110<\/em>(47), 19000\u201319005.\u00a0<\/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\">Vrba, E. S. 1988. \u201cLate Pliocene Climatic Events and Hominid Evolution.\u201d In <em>The <\/em><em>E<\/em><em>volutionary <\/em><em>H<\/em><em>istory of the <\/em><em>R<\/em><em>obust Australopithecines<\/em>, edited by F. E. Grine, 405\u2013426. New York: Aldine.<\/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\">Vrba, Elisabeth S. 1998. \u201cMultiphasic Growth Models and the Evolution of Prolonged Growth Exemplified by Human Brain Evolution.\u201d <em>Journal of Theoretical Biology<\/em> 190 (3): 227\u2013239.<\/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\">Vrba, Elisabeth S. 2000. \u201cMajor Features of Neogene Mammalian Evolution in Africa.\u201d In <em>Cenozoic <\/em><em>G<\/em><em>eology of <\/em><em>S<\/em><em>outhern Africa<\/em>, edited by T. C. Partridge and R. Maud, 277\u2013304<em>.<\/em> Oxford: Oxford University Press.<\/span><\/p>\n<p class=\"import-Normal\"><span style=\"color: #000000\">Walker, Alan C., and Richard E. 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 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><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_219_1046\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_219_1046\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_219_1048\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_219_1048\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_219_1050\"><div class=\"glossary__definition\" role=\"dialog\" 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definition<\/span><\/button><\/div><\/template><\/div>","protected":false},"author":94,"menu_order":7,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-219","chapter","type-chapter","status-publish","hentry"],"part":20,"_links":{"self":[{"href":"https:\/\/opentextbooks.concordia.ca\/explorationsversiontwo\/wp-json\/pressbooks\/v2\/chapters\/219","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/opentextbooks.concordia.ca\/explorationsversiontwo\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/opentextbooks.concordia.ca\/explorationsversiontwo\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/opentextbooks.concordia.ca\/explorationsversiontwo\/wp-json\/wp\/v2\/users\/94"}],"version-history":[{"count":8,"href":"https:\/\/opentextbooks.concordia.ca\/explorationsversiontwo\/wp-json\/pressbooks\/v2\/chapters\/219\/revisions"}],"predecessor-version":[{"id":802,"href":"https:\/\/opentextbooks.concordia.ca\/explorationsversiontwo\/wp-json\/pressbooks\/v2\/chapters\/219\/revisions\/802"}],"part":[{"href":"https:\/\/opentextbooks.concordia.ca\/explorationsversiontwo\/wp-json\/pressbooks\/v2\/parts\/20"}],"metadata":[{"href":"https:\/\/opentextbooks.concordia.ca\/explorationsversiontwo\/wp-json\/pressbooks\/v2\/chapters\/219\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/opentextbooks.concordia.ca\/explorationsversiontwo\/wp-json\/wp\/v2\/media?parent=219"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/opentextbooks.concordia.ca\/explorationsversiontwo\/wp-json\/pressbooks\/v2\/chapter-type?post=219"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/opentextbooks.concordia.ca\/explorationsversiontwo\/wp-json\/wp\/v2\/contributor?post=219"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/opentextbooks.concordia.ca\/explorationsversiontwo\/wp-json\/wp\/v2\/license?post=219"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}