Appreciating Human Diversity

Fifteenth Edition

Conrad Phillip Kottak

University of Michigan

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

McGraw-Hill © 2013 McGraw-Hill Companies. All Rights Reserved.

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THE PRIMATES

C H A P T E R

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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

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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?

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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

Primatology

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Relationships

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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

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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

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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

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Figure 7.1: The Principal Classificatory Units of Zoological Taxonomy

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

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Table 7.2: Primate Taxonomy

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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

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PRIMATE TENDENCIES

• Primates have varied because of adapting to

diverse ecological niches

• Modern primates share homologies reflecting a

common arboreal (living in trees) heritage

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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

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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

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PROSIMIANS

• Primate order has two suborders:

• Prosimians

• Anthropoids

• Early history of primates limited

to prosimian-like animals known

through the fossil record

• The first anthropoids appeared

around 50 million years ago

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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

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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)

Division of Primates

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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

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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

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Figure 7.3: Nostril Structure of Catarrhines and Platyrrhines

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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 and size

• 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

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APES

• Old World monkeys have separate superfamily (Cercopithecoidea)

• Humans and apes make up hominoid superfamily

• Subdivided into families:

• Great apes: orangutans, gorillas, chimpanzees

• Lesser (smaller) apes: gibbons, siamangs

• The third African ape: humans

• 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

• Traits shared by apes and humans

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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

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GIBBONS

• Smallest of the apes

• 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

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Figure 7.4: The Limb Ratio of theArboreal Gibbon and Terrestrial Homo

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ORANGUTANS

• Two existing species

• 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

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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

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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

Cartoon – Jane Goodall

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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

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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

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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