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Primate traitshttps://youtu.be/BpnlS_ach-0
Recall: some important homologies distinguishing the primate order:
*flexible limbs and prehensile hands/feet
*general dental formula and omnivorous diet
*color vision, diurnal, depend on vision more
*delayed maturation/development, more dependence on flexible social behavior and learning
Question: Since...are all adaptations (traits that evolved in response to the environment), what environmental context best explains why primates acquired all these adaptations?
-what environment makes color vision a beneficial adaptation?
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Three hypotheses explaining primate adaptations
Visual-predation hypothesis: many primate traits are adaptations to hunting insects in the lower tiers of the rainforests mya.
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Three hypotheses explaining primate adaptations
Flowering plant hypothesis: primate traits developed the same time flowering plants (angiosperms) diversified globally.
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Three hypotheses explaining primate adaptations
Arboreal hypothesis: many primate traits are adaptations to living in trees
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Three hypotheses explaining primate adaptations
Prosimians: Lemurs and lorises-Madagascar
Ancestral traits-reliance on olfaction
-rhinarium: moist, fleshy pad on noses-shorter gestation/maturation period-dental comb: used to groom and feed
Derived traits-smaller lemurs: nocturnal insectivores-large lemurs: diurnal
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Survey of living primates
Southeast Asia islands
Ancestral-nocturnal-insectivores
Derived-enormous immobile eyes-head can rotate 180 degrees
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Tarsiers
Anthropoids traits
-larger body and brain
-increased reliance on vision
-longer gestation and maturation periods
-increased parental care
-more mutual grooming
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Anthropoids: monkeys apes, humans
Monkeys: 85% of all primate species
Two groups divided geographically: New World monkeys and Old World monkeys
New World Monkeys
Central and South America
Derived-mostly diurnal-exclusively arboreal
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Anthropoids: monkeys apes, humans
Tamarins and marmosets
Ancestral traits-smallest monkeys-claws
-twin births
-males more involved in infant care
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Anthropoids: monkeys apes, humans
Old World Monkeys-tropical forests to semiarid deserts…
Cercopithecidae family
Cecropithecinae subfamily
Ancestral trasts-sexual dimorphism,
e.g., females during estrus have swelling and redness
-quadrupedal
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Anthropoids: monkeys apes, humans
Old World Monkeys-mostly in Africa (except macaques)
Cercopithecines: baboons and macaques
-omnivorous-Ischial Callosities: tough leathery pad on hindquarters
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Anthropoids: monkeys apes, humans
Old World MonkeysAfrica and AsiaColobines: colobus monkeys and Asian langurs
-narrower diet of eat mainly leaves
-Segmented stomachs - digest leaves more efficiently
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Anthropoids: monkeys apes, humans
Characteristics distinguishing hominoids from monkeys
-larger brains and bodies
-shortened trunk
-no tail
-longer infant development periods
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Hominoids - apes and humans
Gibbons-fastest brachiatorshttps://youtu.be/U3JhwjNfx_g-curved fingers, muscled shoulders
OrangutansBorneo and SumatraCharacteristics-almost completely arboreal-sexual dimorphism
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Hominoids - apes and humans
GorillasAfrica: eastern lowland, western lowland, and mountain gorillas
Characteristics-largest primates-primarily terrestrial-'knuckle-walkers'
sexual dimorphism: 400 lbs males vs 200 lbs females
Social organization: natal group-vegetarian
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Hominoids - apes and humans
ChimpanzeesEquatorial Africa
Characteristics-anatomically similar to gorillas-knuckle-walking on ground, brachiation in trees
Diet: variety of plants and animal foods
Social: large fluid communities; form lifelong attachments
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Hominoids - chimpanzees
BonobosAreas south of Zaire River
Characteristics-similar to chimpanzees only less sexual dimorphism
-includes frequent copulations throughout female estrous cycle
-stable male-female bonding
-more frequent sexual activity and sexual activity between members of the same sex
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Hominoids - bonobos
Scientific name for our species:
Homo sapiens
-italicize-Genus is capitalized -species lowercase
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Hominoids - humans
Found everywhere in all climates
-generalized features like the other apes-omnivorous
Characteristics-only living bipeds
-entirely dependent on culture
-brainsize increased enormously
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Hominoids - humans
Behaviors: anything organisms do in response to external/internal stimuli
Affected by: -genetics
-environment
-Instinctual behaviors: fixed behaviors animals born with
-Plastic behaviors: flexible, learned, and feature prominently in primates
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Behavior in general
Group structure can influence behavior
Dominance hierarchies-system of social organization ranking individuals by relative access to resources
-common in primates: resources for male can include access to females
-ranks are learned and can change
https://youtu.be/HDxA8-01cp4
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Social behavior
Primate social structure influenced by reproductive strategies and behavior
*Social structures common in primates
Multi-female, multi-male (most common) e.g., chimpanzees
Polygyny, i.e., multi-female, single-male (common) e.g., gorillas, baboons
Monogamy (uncommon) e.g., gibbons
Polyandry, i.e., single-female, multi-male (least common) e.g., red lion tamarins
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Affiliative: friendly relations between individuals; promotes group cohesion
Grooming - picking debris out of the fur of another individual-reinforces social bonds-most important affiliative behaviors among primates
Aggressive: conflict between individuals; promotes group separation
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Group behavior in primates
Grooming - picking debris out of the fur of another individual-reinforces social bonds
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Group behavior in primates
Animals use different reproductive strategies to improve reproductive success
r-selection: relatively large number of offspring; reduced parental care
K-selection: opposite
Species either use r or K-selection reproductive strategies
Females and males in mammals use these reproductive strategies
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Reproductive behavior - in general and in primates
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Primates, like all other animal with complex social behavior compete for good mating opportunities
Sexual dimorphism: more common in species with high male competition,
e.g., Orangutan dominant males have pads on face
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Reproductive behavior - in primates
-higher-ranked individuals communicate dominance to lower-ranking, subordinates
Submission behavior communicates acknowledgement of dominance hierarchy
E.g., exposing hindquarters to higher-ranks, allowing higher-ranks mount subordinates
Displays of aggressive behavior communicate rank and maintains group cohesion by reducing violent conflicts
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Communication
-involuntary utterances used to express present emotional states
Vervet monkeys: specific vocalizations for birds, snakes, leopards Only present tense
Language and humans: human language is distinct
-Relies on a set of arbitrary symbols used in written and spoken communication
-Used to convey abstract concepts like the past and future
E.g., displacement - communication about objects not currently present
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Animal communication versus language
Primates learn complex social behaviors that resemble our culture
E.g., in Koko and Kanzi
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Primate cultural behavior
Primates learn complex social behaviors that resemble our culture
E.g., in Koko and Kanzi
Both demonstrate the ape capacity to learn to communicate, but lack syntax and grammar like humans.
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Primate cultural behavior
E.g., chimpanzees…
Stone hammers used across generations
Variation in tool design seen in different chimpanzee behaviors
Termite fishing
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Primate “cultural” behavior
E.g., chimpanzees…
Stone hammers used across generations
Variation in tool design seen in different chimpanzee behaviors
Termite fishing
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Primate “cultural” behavior
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