A n t h r o p o l o g y

A n t h r o p o l o g y Appreciating Human Diversity Fifteenth Edition Conrad Phillip Kottak University of Michigan McGraw-Hill 2013 McGraw-Hill Companies. All Rights Reserved.

C H A P T E R THE PRIMATES 7-2

THE PRIMATES Our Place Among Primates Homologies and Analogies Primate Tendencies Prosimians Monkeys Apes Behavioral Ecology and Fitness Primate Evolution Chronology Early Primates Miocene Hominoids 7-3

THE PRIMATES How and why are monkeys and apes similar to humans? When, where, and how did the first primates, monkeys, apes, and hominids evolve? How did diversity among Miocene proto-apes figure in hominid origins? 7-4

PRIMATOLOGY Primatology: the study of nonhuman primates fossils and living apes, monkeys, and prosimians including their behavior and social life; helps anthropologists make inferences about early social organization of hominids Two kinds of primates are especially relevant: Terrestrial monkeys and apes: primates that live on the ground rather than in trees (ecological adaptation similar to humans) Great apes (chimps, gorillas, orangutans, bonobos), specifically chimpanzees and gorillas Most closely related to us Humans and apes share a common ancestor; humans did not descend from apes 7-5

OUR PLACE AMONG PRIMATES Similarities between humans and apes are evident in anatomy, brain structure, genetics, and biochemistry; physical similarities between humans and apes are recognized through zoological taxonomy Taxonomy: assignment of organisms to categories Classifications based on degree of genetic relatedness Phylogeny: genetic relatedness based on common ancestry Hominoidea (hominoids): a superfamily containing humans and apes Classification of descending hierarchy, from most inclusive to least inclusive Species: group of organisms whose mating produces viable and fertile offspring 7-6

OUR PLACE AMONG PRIMATES Homologies: similarities that organisms share because of a common ancestry; similarities used to assign organisms to the same taxon (category) Biochemical homologies between apes and humans confirm common ancestry (i.e. humans, chimps, and gorillas have more than 98% of their DNA in common) Humans: mammals (class) (share traits like mammary glands) that belong to the order of primates (order) Primates share structural and biochemical homologies that distinguish them from other mammals (i.e. versus carnivore, rodentia) Resemblances have been inherited from common early primate ancestors Humans, whales, bats, eagles, lizards, frogs, and chimps forelimb bones 7-7

Figure 7.1: The Principal Classificatory Units of Zoological Taxonomy 7-8

Table 7.1: The Place of Humans (Homo sapiens) in Zoological Taxonomy 7-9

Table 7.2: Primate Taxonomy 7-10

HOMOLOGIES AND ANALOGIES Extensive biochemical homologies between apes and humans confer a common ancestry Analogies: similar traits that arise if species experience similar selective forces and adapt to them in similar ways; not result of common ancestry Dolphin and fish Convergent evolution: process by which analogies are produced 7-11

HOMOLOGIES AND ANALOGIES Hominid: the zoological family that includes fossils and living humans, chimpanzees, gorillas, and their common ancestors Hominin (tribe) describes all human species that have ever existed, excluding chimps and gorillas 7-12

PRIMATE TENDENCIES Primates have varied because of adapting to diverse ecological niches Modern primates share homologies reflecting a common arboreal (living in trees) heritage 7-13

PRIMATE TENDENCIES Many trends in primate evolution best exemplified by anthropoids: monkeys, apes, and humans Grasping: Five-digited feet opposable thumbs can touch all other fingers Flexible hands and feet Adaptation of hominins to bipedal locomotion: two-footed, upright locomotion eliminated foot s grasping ability Shift from smell to sight Stereoscopic vision Eye placement Brain organization Color vision 7-14

PRIMATE TENDENCIES Hand, rather than nose, is main touch organ Increased brain complexity Parental investment in single offspring Longer development period More attentive care More opportunities for learning Increased social complexity Sociality Social animals that live with others of their species Associated with parental investment Support of social group valuable 7-15

PROSIMIANS Primate order has two suborders: Prosimians Anthropoids Early history of primates limited to prosimianlike animals known through the fossil record The first anthropoids appeared around 50 million years ago 7-16

PROSIMIANS Some prosimians managed to survive in Africa and Asia because they adapted to nocturnal life They do not compete with anthropoids, which are active during the day Lemurs Tarsiers Lorises 7-17

MONKEYS All anthropoids share resemblances that can be considered trends in primate evolution Anthropoid suborder has two infraorders: Platyrrhines: flat-nosed, New World monkeys Catarrhines: sharp-nosed, Old World monkeys, hominoids (apes and humans) 7-18

MONKEYS Different infraorder - New world monkeys (platyrrhines) were reproductively isolated from the catarrhines before the latter split into the Old World monkeys, apes, and humans All New World monkeys, and many Old World ones, are arboreal Monkeys move differently from apes and humans Their arms and legs are about same length & move parallel to each other Most monkeys have tails 7-19

NEW WORLD MONKEYS Live in the forests of Central and South America arboreal Have prehensile, or grasping, tails With one exception (night or owl monkey), all monkeys, apes, and humans are diurnal 7-20

Figure 7.3: Nostril Structure of Catarrhines and Platyrrhines 7-21

OLD WORLD MONKEYS Terrestrial and Arboreal Significant distinctions exist between arboreal and terrestrial Old World monkeys Size: arboreal monkeys smaller than terrestrial ones Sexual dimorphism: marked differences in male and female anatomy and temperament Terrestrial males significantly larger and fiercer than terrestrial females, but little or no such differentiation exists among arboreal monkeys Terrestrial monkeys - specializations in anatomy, psychology, and social behavior enable them to cope with terrestrial life Social organization: Old World Monkeys Males seek mates outside natal group Core group of females Chimps and gorillas Females more likely to leave natal group to seek mates 7-22

APES Old World monkeys have separate superfamily (Cercopithecoidea) Humans and apes make up hominoid superfamily (Hominoidea) Subdivided into families: Great apes: orangutans, gorillas, chimpanzees Lesser (smaller) apes: gibbons, siamangs The third African ape: humans 7-23

APES Live in forest and woodlands Light and agile gibbons are completely arboreal Skilled brachiation: hand-over-hand movement through the trees Heavier gorillas, chimpanzees, and adult male orangutans spend considerable time on the ground Ape behavior and anatomy reveal past and present adaptation to arboreal life 7-24

Smallest of the apes GIBBONS Spend most of their time just below the forest canopy Use arms as balance when they occasionally walk erect Tend to live in primary groups composed of permanently bonded males and females and their preadolescent offspring Siamangs slightly larger relative 7-25

Figure 7.4: The Limb Ratio of the Arboreal Gibbon and Terrestrial Homo 7-26

Two existing species ORANGUTANS Marked sexual dimorphism Male is between chimps and gorillas in size (large, approx. 200 lbs.) Move between arboreal and terrestrial habitats Tend to be solitary Tightest social units: females and preadolescent young 7-27

GORILLAS Three subspecies: Western lowland Eastern lowland Mountain (largest) Largest - Full-grown male may be 400 pounds, 6 feet tall Marked sexual dimorphism Female weighs half as much as male Primarily terrestrial Build nests in trees to sleep Live in a troop of males and females with their offspring Silverback male only male breeder 7-28

CHIMPANZEES Two kinds of chimpanzee: Common Pygmy (Bonobo) Adult males weigh 100 to 200 pounds Less sexual dimorphism than gorillas About the same as humans Social organization relatively well known Jane Goodall Communities of about 50 chimps that regularly split into smaller groups Exhibit dominance in relationships Chimps greet with gestures, facial expressions, and calls Social network of males closer; females more likely to migrate outside natal group to find mate Occasional hunting parties 7-29

BONOBOS Live in humid forests of Democratic Republic of Congo Adult males average 95 pounds Female-centered communities Peace loving Egalitarian Frequently use sex to avoid conflict within community 7-30

BEHAVIORAL ECOLOGY AND FITNESS Behavioral ecology: study of evolutionary basis for social behavior Assumes genetic features of any species reflect a long history of differential reproductive success (natural selection) Biological traits are transmitted across generations because they enabled ancestors to survive and reproduce more effectively than competition Natural selection is based on differential reproductive success Members of same species may compete to maximize their reproductive fitness Individual fitness measured by number of direct descendants an individual has Inclusive fitness is measured by genes one shares with relatives Genetic contribution enhanced by cooperation, sharing, and other unselfish behavior Individuals may invest in kin relations; sacrificing for kin increases genetic contribution through shared genes 7-31

BEHAVIORAL ECOLOGY AND FITNESS Maternal care always makes sense in terms of the reproductive fitness theory, because females know that offspring are their own If male cannot be sure about an offspring s paternity, it may make sense to invest in a sister s offspring, because of shared genes 7-32