Unit 4 continuedPrimates and primate behavior

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PrimatesTraits found across the primate order

*Tendency towards erect posture*Highly prehensile hands and feet*Generalized dentition*Reliance on complex behavior

What accounts for these traits?

Why did such adaptive features emerge in the first place?

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Arboreal hypothesisCluster of primate traits are the result of living in the trees.

Evidence for:-highly prehensile hands and feet-generalized diet fits with the niche

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Arboreal hypothesisCluster of primate traits are the result of living in the trees.

Evidence for:-highly prehensile hands and feet-generalized diet fits with the niche

Evidence against:-other mammals live in the trees but lack primate characteristics

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Visual adaptation hypothesisCluster of primate traits are the result of the visual emphasis of insect predation

Evidence for:-accurate, 3-D vision-grasping hands and feet

Evidence against:-primates are characterized by a generalized diet and dentition

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Angiosperm radiation hypothesisCluster of primate traits are adaptive responses to the radiation of flowering plants

Evidence for:-diverse set of foods make generalized diet more likely-explains emergence of color vision

Evidence against:-Angiosperms appeared millions of years before primates

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StrepsirhiniGroups: Lemurs and lorises

Compared to the haplorhines

-more ancestral

-more reliance on olfaction

-less reliance on complex behavior

-faster maturation rates

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Haplorhines - monkeys, apes, and humansPlatyrrhinesNew world monkeys-prehensile tails, found in South America

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Catarrhines (Africa and Asia)Old world monkeys, apes, and humans

CercopithecoidsOld world monkeys

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Haplorhines - monkeys, apes, and humans

Catarrhines (Africa and Asia)Old world monkeys, apes, and humans

CercopithecoidsOld world monkeys

Cercopithecines (baboons, macaques, etc)1. Ischial callosities - sitting pad composed of callused skin2. Estrus - period of female sexual receptivity (correlated with ovulation)

Colobines (leaf-eating monkeys)Tarsiers (some traits from both subfamilies)

Hominoids(apes and humans) - see rest of the ppt

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Haplorhines - monkeys, apes, and humans

Hominoids - the apes and humansCompared to the other haplorhines, hominoids:

Location: Asia and Africa-larger body size-lack a tail-shoulders adapted for suspensory behavior-more complex behavior-increased period of infant dependency

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Gibbons and Siamangs

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Location: Asia

Morphology: traits reflecting adaptation to brachiation

Behavior: territorial; social unit = adult male and female and their offspring

Orangutans

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Location: Islands of Sumatra and Borneo

Morphology: sexual dimorphism between male/female body size

Diet: frugivorous

Behavior: mostly solitary

Gorillas

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Location: West/east equatorial Africa

Morphology: largest living primates; also sexual dimorphism between male/female body size

Diet: vegetarian

Behavior: Groups with one or two adult silver back males, several females and offspring

Chimpanzees

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Location: equatorial Africa

Morphology: smaller body size; less pronounced sexual dimorphism

Diet: varied diet (fruits, leaves, and hunting small animals)

Behavior: live in large communities; complex social interactions emphasizing male-male bonds

Bonobos

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Location: Near Zaire River

Morphology: similar body size to chimpanzees

Diet: varied diet

Behavior: fluid communities; complex social interactions emphasizing male-female bonds; copulate throughout female estrous cycle

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Humans

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Location: Everywhere

Morphology:adaptations of the pelvis, leg, and foot enable habitual bipedalism

Diet: generally omnivorous

Behavior: Completely dependent on culture