In this chapter students will learn:

• why it is important to understand humans as part of the primate world.
• the basics of primate taxonomy.
• about key events in primate evolution.
• the methods anthropologists use to study primates in the wild.
• the principal research interests and findings of anthropolgists studying nonhuman primate behavior.

Introduction
Considering humans as primates is important for many reasons, including making inferences about how people evolved, both biologically and culturally.

Primate Taxonomy
Homo sapiens are one of about 500 species of primates. Humans are categorized as being a member of the suborder Haplorhini, Infraorder Catarrhini, Superfamily Hominoidea, and Family Homininae. Major non-human primate groups include strepsirrhines, platyrrhines, cercopithecoids, cebids.

Primate Evolution
The order Primates emerged in the Palaeocene (65–55 mya). There were many varieties of primate in the Eocene (55–34 mya). Catarrhini and Platyrrhini were on separate evolutionary tracks by the end of the Oligocene (34–24 mya). Hominoids and Hominins emerged in the Miocene (24–5 mya).

Primate Behavior
Principal research interests in primatology include communication, social structure, aggressive and affiliative behaviors, subsistence and diet, and tool use.

Primates in Crisis: Ecological Stability and Critical Thinking
Approximately half of the 500 species of primate species are endangered. This is largely due to loss of habitats, considering primates as pests, the market for primates as pets and for zoos, and the eating of primates by humans for food.

1. Why is it important to understand humans as primates?

2. What are the distinguishing characteristics of primates, Haplorhini, Catarrhini, and Hominoidea?

3. What were the key events in primate evolution occurring in each of epoch of the Cenozoic?

4. What are the principal research interests in primatology? Give examples of discoveries for each.

1. What might be some implications for anthropology if the loss of primates continues?

2. What may be some implications of using bonobos, rather than chimpanzees, as models of how early humans may have behaved?

3. What are some of the implications of having no consensus on primate taxonomy, such as some people restricting the use of “hominin” to refer only to humans while others also classify chimpanzees and bonobos as hominins?

adaptive radiation a process by which one species occupies a new ecological niche, quickly increasing its population and diversifying into new species

affiliative friendly

Anthropocene a proposed geological period to describe the years in which humans have had a significant impact on the environment, observable in the geological record; there is no consensus on the validity of the term to describe the geological period or when such a period began

brachiation a form of locomotion primarily by arm-over-arm swinging

bushmeat meat from wild animals, usually referring to animals from forested regions of Africa

Catarrhini primate infraorder, including Old World monkeys, apes, and humans

dental formula the kind and number of teeth, usually described for one quarter of the mouth

egalitarian describes a society in which every member has the same access to resources and status; non-hierarchical

folivory a diet focusing on leaves and other rough plant foliage

frugivory a diet focusing on fruit

genus a taxonomic category, above the level of species

Haplorhini a suborder of Primates, including monkeys, apes, and humans

Hominoidea a superfamily of the infraorder Catarrhini; Hominoidea includes apes and humans

Hylobatidaeone of the three families of the superfamily Hominoidea; Hylobatidae includes gibbons and siamangs, otherwise known as Lesser Apes

insectivory diet focusing on insects

olfaction sense of smell

omnivorous diet including a wide variety of plants and animals

ontogeny the development of an individual from conception to maturity

Pan genus to which chimpanzees and bonobos belong

Platyrrhini Primate infraorder, commonly known as New World monkeys

Pongidae one of the three families of the superfamily Hominoidea; some use Pongidae to refer to the three genera of Pongo, Gorilla, and Pan while others use it only for Pongo

Pongo genus to which orangutans belong

prehensile the ability to grasp

rhinarium the fleshy part at the end of the nose of Strepsirrhini, and many other animals

speciesa population that can mate and produce fertile offspring in natural conditions

Strepsirhini a suborder of Primates, including lemurs and lorises

superfamily a taxonomic category; a subdivision of infraorder

taxa a category in the system of biological classification of organisms

taxonomic order subdivision of a taxonomic class in the biological classification system; primates are an order of the class Mammalia

Among the Wild Chimpanzees (video). National Geographic.

Champions of the Wild (Video Series). Omni Film and National Film Board of Canada.

De Queiroz, A. (2014). The Monkey’s Voyage: How Improbable Journeys Shaped the History of Life. New York, NY: Basic Books.

Strier, K. (2011). Primate Behavioral Ecology (4^th edition). New York, NY: Pearson.

Tuttle, R. (2014). Apes and Human Evolution. Cambridge, MA: Harvard University Press.

Bigfoot Field Researchers Organization
bfro.net

Jane Goodall Institute
janegoodall.org/

Primatology.net
primatology.net

1. List as many distinguishing characteristics of primates as you can, explaining which are relevant for humans; in the case of those that are not relevant, explain how or why these characteristics may have been relevant at one point. What evolutionary advantages do these characteristics bestow upon their recipients?

2. What kinds of biological adaptations do primates have to their diets, and how might these benefit them?

3. Why are rafts considered to be a critical factor in past primate evolution? Do you find this theory plausible?

4. You discover a new kind of primate while conducting fieldwork. You note that it has a large brain, is nocturnal, has a keen sense of smell to go along with its large nose, and has five sharp claws it uses to travel between trees. What suborder would you classify it as, and why? Follow-up: if you then noted it had a very developed sense of vision, would that change your classification?

5. What are some of the most critical findings about the major epochs that contribute to understanding humans today and/or primate taxonomy?

6. How does one’s interpretation of human behavior today and in the past differ when using chimpanzees versus bonobos as a possible yardstick?

7. What are some of the major research interests in primatology? Give an example of a nonhuman and human behavior for each.

8. Many primates are endangered. Why is this the case, and what arguments exist in favor of conservation and rehabilitation for primates?

9. What evidence would it take for you to accept the existence of Bigfoot? What likely characteristics would you expect such a creature to have, and how might this be different from existent beliefs?

10. What kinds of real-world applications can be derived from anthropological studies of primates?

Answers

1. The answer should include a good number of the characteristics listed below, and should clearly define them. Additionally, a thorough understanding of how they relate to human evolution (and their advantages) can be given through many different possible examples.

• prehensile hands and feet (tool use, etc.)
• nails instead of claws (dexterity)
• forward-facing eyes/stereoscopic vision
• large brains
• single offspring
• long period of infant dependency
• diurnal
• arboreal
• movement (climbing, brachiation, bipedalism, etc.)
• social
• non-specialized diets

See pages 33 of your text.

2. The answer should explain the difference between the three main dietary strategies and what consequences these strategies can have on behavior (and vice versa).

• Frugivory: a diet focused on fruits.
• Folivory: a diet focused on foliage.
• Insectivory: a diet focused on insects.
• All have consequences on approximate body size (insectivores tend to be smaller, etc.).
• Diet strategies can be alternated, depending on behaviors and availability (for example, orangutans having a diet that is 90 per cent frugivorous in one month and folivorous in another).
• Diet is linked to biology through teeth (certain teeth shapes perform different functions more efficiently), digestive systems (stomachs, etc.), and physical characteristics such as pouches.
• Diet is also linked to geographical area, in that primates may occupy the same or different areas as other primates, depending in part on the relative diet strategies.

See pages 35 of your text.

3. The answer should situate why the movement of primates on rafts is significant overall within evolutionary theory, as well as the specifics of the strengths/weaknesses of the raft hypothesis.

• The existence of primates in the fossil records of Central and South America begin to appear around 30 million years ago, but how they got there is not definitively known.
• An interesting hypothesis suggests that the earliest Platyrrihini rafted over from Africa. The rafts were presumably floating islands of natural debris. Naturally occurring large rafts are known to exist, and could have supported such a movement; other (smaller) species have been known to make such journeys.
• Some primate fossils from the Oligocene in Africa appear to be a good candidate for an ancestor to both the Platyrrhini and Catarrhini, including, for example, having the dental formula most commonly associated with Platyrrhini.
• Several kinds of evidence support this theory, including the knowledge that primates made it hundreds of miles from Africa to the island of Madagascar tens of millions of years ago (presumably by rafting on floating vegetation), and in more recent times, the apparent travel by early populations of humans to some of the islands of southeast Asia.
• The distance the primates would have had to travel was likely much shorter than it is today and could have been measured in days.

See page 43 of your text.

4. The answer should most likely classify it as Strepsirhini (vs. Haplorhini), since the majority of characteristics fit that suborder. The answer should demonstrate a familiarity with why certain characteristics are beneficial for different suborders/species, and acknowledge the variation that can occur in labeling or classifying animals (i.e., different people can come to different conclusions).

• Strepsirhini have a greater reliance on olfaction, with rhinariums.
• Most nocturnal primates belong to this suborder, as well as those with claws.
• The large brain could be an anomaly to this categorization, but one anomaly does not necessarily mean classification as Strepsirhini will not work.
• When complicated by another anomaly—developed sense of vision—the answer could go either way and will depend on your justification and understanding of how and why classification taxonomies are imperfect.

See pages 37-40 of your text.

5. Answer should cover the major epochs and their relation to primate evolution.

• Palaeocene: sketchy fossil record, but likely when primates emerged. A potential primate from this period is Purgatorius.
• Eocene: Primates now well established, with at least a dozen species (and as many as 200). Key characteristics include those relating to vision and prehensibility. This was also the last common ancestor of monkeys, apes, and humans (and a split between Strepsirhini and Haplorhini).
• Oligocene: A further split in the primate family tree (Catarhinni and Platyrhinni), and when the proposed rafting occurred to Central/South America.
• Miocene: Further subdivision (Hominoidea and Homininae), and the last common ancestor of orangutans, gorillas, chimpanzees, and bonobos (20 million years ago), and the last common ancestor of chimpanzees, bonobos, and humans occurring 7 million years ago.
• Pliocene: Multiple genera of Homininae now exist, and the genus Homo emerges.
• Pleistocene: Many species of humans exist, and the last common ancestor of chimpanzees and bonobos lived about one million years ago.
• Holocene: Homo sapiens dominates.

See pages 39-42 of your text.

6. This answer should demonstrate familiarity with characteristics that chimpanzees and bonobos share with humans, and with their relative differing aspects. It should also indicate the knowledge of how evolution overall works, namely, how having a common ancestor does not mean being directly descended from it, as well as why and how studying primate behavior helps us understand human behavior.

• Primate behavior offers a model for how early humans may have lived, as well as understandings of the advantages that all primates have in certain areas.
• The basic question regarding evolutionary relationships between the three species: Was aggression (sometimes lethal) a trait of the common ancestor of chimpanzees, bonobos, and humans that was then lost in bonobos? Or did aggression (mostly male and sometimes lethal) evolve separately in chimpanzees or humans?
• Chimpanzees and humans are the only two primates who hunt cooperatively for meat. Chimpanzee groups are also hierarchal, male-dominated, and aggressive.
• Bonobos and humans are incredibly social primates, using affiliative behaviors. Bonobos are egalitarian and use sex to resolve conflicts (an argument can be made that humans do this as well).

See pages 46-51 of your text.

7. Five interests are provided in the text. Answers should detail what is studied in each interest, and include an example of nonhuman behavior from the text. It should also include an example of human behavior not from the text (independent thought) in order to solidify one’s understanding of how humans are a part of the primate world.

• Communication: Includes vocalizations, gestures, expressions, and language. Nonhuman examples: gorillas using chest beatings, or any primate calling out a warning about a predator.
• Social Structure: How groups are formed. Nonhuman examples: female spider monkeys leave their home group; male capuchin monkeys leave their home group.
• Aggressive and Affiliative Behavior: How primates deal with conflict and/or relationships. Nonhuman examples: grooming and hugging, physical displays, threats.
• Subsistence and Diet: strategies of acquiring food. Nonhuman examples: gorillas eating over 150 kinds of plants, chimpanzees sometimes hunting for meat.
• Tool Use: Adapting resources as a means of manipulating a situation. Nonhuman examples: chimpanzees using sticks to poke small animals, gorillas using sticks to measure water depth.

See pages 46-51 of your text.

8. The answer should clearly explain the major reasons primates are in crisis, while explaining the associated consequences of such endangerment. Overall, the emphasis should be on how a decreased number of primates creates numerous, complex problems.

• Habitat loss (forests being cleared, leading to starvation and/or lack of suitable living environments).
• Primates viewed as pests (for example, being killed to prevent them from eating crops).
• Primates trafficked as pets and for zoos. (Whether opportunistic or planned, this often also involves killing the primate parents so their infants can be sold. As pets or tourist attractions, primates are no longer in their natural environments and cannot breed/live in suitable conditions.)
• Bushmeat/food (pathogen risks).
• Overall consequences of a decreased primate population: Natural forests and ecosystems are transformed, especially tropical and semitropical forests. Seed dispersal is hindered.

See page 52 of your text.

9. This answer requires some personal justification, so the specifics may vary. In general, the answer should provide information that demonstrates your familiarity with how primates are classified and what kinds of biological evidence are appropriate (when compared to vague evidence such as personal anecdotes). It should also explain which characteristics are most frequently found together.

• Bigfoot is said to be large, hairy, bipedal, solitary, omnivorous, and present in North America. These characteristics are often at odds with one another (e.g., the majority of nocturnal primate species tend to be small, and are quite removed from apes and humans in the taxonomy).

See page 54 of your text.

10. The answer can vary, but could include any of the following:

• Ecological sustainability.
• Environmental awareness and conservation efforts.
• Cultural and/or economic reasons for killing/eating primates.
• Understandings of biological taxonomies and common ancestors.
• Perspective on how early humans interacted and lived (as well as how remnants of these behaviors remain today).
• Rehabilitation centers.

See pages 48-49 and 51-53 of your text.

1. The definition of hominin varies because

• a) scientists are currently revising how to define the newest epoch (the Anthropocene). Some believe that the category hominin should reflect contemporary political and social controversies.
• b) it is the root class from which all orders and family designations are derived.
• c) some researchers believe different taxonomic categorizations should be used for extinct species.
• d) different taxomic frameworks define it differently. For example, in some taxonomies, only humans are considered to be interchangeable with the term hominin, whereas in another, humans are only one type of hominin.

2. If humans were more closely related to mandrills, which characteristic might they share?

• a) a tail
• b) stereoscopic vision
• c) a 2–2–2–1 dental formula.
• d) the ability to brachiate

3. What distinguishing characteristics within the primate taxonomy do humans not have?

• a) prehensility, a long period of infant dependency
• b) diurnality, large brains
• c) rhinarium, nocturnality
• d) stereoscopic vision, nails (not claws)

4. The categories Catarhini and Platyrhini refer to

• a) the two superfamily categories, which likely split during the Miocene epoch.
• b) the two suborders of Primates, which likely split during the Eocene epoch.
• c) two infraorders, which are roughly synonymous with “New World monkeys” and “Old World monkeys” (the latter contains all primates with prehensile tails).
• d) two infraorders that likely diverged in the Oliogocene epoch.

5. What would be considered an example of a social activity among primates?

• a) Tool use.
• b) Grooming.
• c) Defecation.
• d) Dreaming.

6. Identifying and classifying primates from the past

• a) is impossible without contemporary examples.
• b) is complicated by the small sample size and the age of the bones.
• c) is easy when using the dental formula.
• d) is complicated by the skull being the only skeletal element able to identify primates.

7. While in the field, anthropologists

• a) often become involved in additional objectives, such as rehabilitation and conservation.
• b) must remain objective and not get involved with local issues.
• c) dictate to the local communities what they need to do to protect primates.
• d) are a major economic boon for local communities.

8. The dental formula for Catarhini is

• a) distinct from Hominoidea.
• b) missing the third molar.
• c) evolved for folivory.
• d) the same in each quarter of the mouth.

9. Hunting and eating meat is

• a) only observed in humans.
• b) observed in all Hominoidea species.
• c) observed in all primates.
• d) observed in some monkeys, chimpanzees, and humans.

10. The epoch known as the Pleistocene

• a) occurred in the Mesozoic era.
• b) follows the Holocene, being based on significant and recent human-made changes, but is not an official classification.
• c) follows the Pliocene, and contains the time span in which Homo sapiens dominates.
• d) is the epoch in which primates probably first emerged.

Answers

1. d

Feedback: Categorization systems are not inherently natural; they are developed by humans and subject to interpretation.

See page 40.

2. a

Feedback: Mandrills are Cercopithecoidea, also known as Old World monkeys. Cercopithecoidea have tails (but they are not prehensile).

See page 37-38.

3. c

Feedback: Humans are active during the day (not night). A rhinarium is the fleshy part at the end of the nose of Strepsirhini.

See pages 37-38.

4. c

Feedback: There are two infraorders of Haplorhini that anthropologists study: the Platyrrhini and the Catarrhini

See page 36.

5. b

Feedback: One of the most common affiliative behaviors among primates is grooming. The hygienic aspect of grooming, such as removing bugs and dead skin, is usually viewed as a byproduct of grooming as a process of socialization. It is largely viewed as a social activity, reaffirming alliances, relationships, and group cohesion. Other affiliative behaviors seen among primates include hugging, patting, and kissing.

See page 47-50.

6. b

Feedback: When assigning various remains to different species, we are making assumptions about the ability of different animals to mate and produce fertile offspring, based on bones that are sometimes tens of millions of years old. We really don’t know the variability with various species, genera, and other categories. We are also hampered by a relatively small sample size.

See pages 41-42.

7. a

Feedback: Many primatologists start their field studies firmly embedded in an anthropological framework, with the ideal of contributing to the methods, theories, and discoveries of the discipline. Once in the field, however, it is not unusual for researchers to shift some of their focus toward additional objectives, including rehabilitation and conservation.

See pages 45-46.

8. d

Feedback: Dental formula refers to the kind and number of teeth in the mouth. It is usually expressed as a series of numbers for each quarter of the mouth, going from front to back. All Catarrhini, including humans, have the same dental formula, commonly expressed as 2–1–2–3, where the first “2” indicates incisors, the “1” represents canines; the second “2” represents premolars, and the “3” represents molars. Among Catarrhini, this dental formula is the same for each quarter of the mouth: upper right, upper left, lower right, lower left.

See page 38.

9. d

Feedback: Some monkeys have been observed hunting and eating meat, but most studies of hunting and meat eating focus on chimpanzees. Hunting and meat eating are very interesting to anthropologists since our human ancestors started focusing on hunting and meat eating more than one million years ago, and we are uncertain of how and why that occurred.

See pages 50.

10. c

Feedback: Answer B refers to the Anthropocene, a possible new epoch based on the significance of changes to the earth in recent times caused by humans, but it is not widely accepted; the rest of the answers are detailed in Table 2.5.

See page 44.