Shared derived hominoid traits:

-Larger body to brain size ratio-Longer arms, shorter trunk and legs-No tail-Longer developmental periods-More complex brains and behavior

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Hominoids: apes and humans

-Tropic areas of southeast Asia-Omnivorous

Adaptations to brachiation (suspensory locomotion involving arm swinging): -Muscled shoulders-Long arms-Curved fingers

https://youtu.be/U3JhwjNfx_g 2

Apes: Gibbons and Siamangs

-Forests of Borneo and Sumatra-Frugivorous

-Almost completely arboreal-Solitary

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Apes: Orangutans

-Africa (east/west lowland, and mountain gorillas)-Vegetarians

-Largest living primates-Sexual dimorphism

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Apes: Gorillas

-Equatorial Africa-Omnivorous plus other animals

-Knuckle-walking on ground-Brachiation in trees

-Large fluid communities-Form lifelong attachments

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Apes: Chimpanzees

-South of Zaire River-Omnivorous

-Copulate throughout estrus cycle-Female-centered communities-Female-female and male-male sexual behaviors

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Apes: Bonobos

Homo sapiens-Every continent-Omnivorous

-Only living bipeds-Brainsize increased enormously-Entirely dependent on culture

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Humans

-Study of nonhuman primate behavior and biology.

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Primatology

Behavior: an organism's response to external/internal stimuli.

Behavioral ecology: all biological components of an ecological system evolved together.

Behaviors = adaptations: natural selection acts on behaviors.

-Primates = highly social so interested in social behavior.

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Behavior and behavioral ecology

Diet: weigh energy gained by food against energy expended obtaining food.

Distribution of resources: leaves are abundant, fruit dispersed on trees (groups split up and forage), etc.

Predation: high predation makes larger groups more advantageous.

https://youtu.be/LU8DDYz68kM

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Factors influencing social structure

Reproductive strategies: produce and successfully rear to adulthood as many offspring as possible.

R-selected: produce many offspring, little parental investment.

K-selected: produce few offspring, more parental investment.

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Reproductive behaviors

Primates are K-selected

-Females compete for resources benefitting offspring care.

-Males compete for access to females.

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Primate reproductive strategies

Sexual dimorphism: due to high male competition-Larger male body size and teethEstrus: swelling of skin around female genital area-Visual cue of female's readiness to mate

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Primate reproductive strategies

-Social organization system wherein individuals are ranked relative to one another-Rank based on access to resources

-Learn rank via interactions with group members-Communicate dominant/subordinate position

Benefits -Higher rank = higher reproductive success-Reduces physical violence

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Primate dominance hierarchies

-Acts conveying info to another individual (the recipient).-Changes the behavior of the recipient

Autonomic responses: involuntary (scents, hair standing up,...)

Intentional responses: voluntary (body posture, vocalizations,...)

-Primates communicate submission, reassurance, warnings

Ex. Monkey alarm calls for birds, snakes, leopards.

https://youtu.be/o-bxPLFt1vI 15

Communication

-Conflict between group members-Often due to competition for resources

Displays: repetitious behaviors communicating emotional states (chest-slapping, waving-branches,...)

Mountings: expresses dominance

Both-Reduce physical violence-Reinforce rank in dominance hierarchy

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Aggressive behaviors

-Amicable-Promote social cohesion-Reassurance communicated via petting, hugging, holding hands,...

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Affiliative behaviors

Grooming: picking debris out of another individual's fur-Reinforces social bonds

Seen in many social contexts: moms groom infants, males groom females, subordinate groom dominant

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Affiliative behaviors

Animal communication-Conveys present emotional states

Human language-Uses arbitrary symbols-Conveys abstract concepts (ex: past and future)-Grammar and syntax

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Animal communication vs language