hominoids: apes and humans -longer arms, shorter trunk and
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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
-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
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