Hominoids and Primate behaviorPart 1 from Monday

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Today*Quizzes and grades update

*Midterm info

*Look at the apes

*Primate behavior

*Origins

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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

Primate social unitBasic primate social unit: female and her infant(s)

Note: nonhuman primates learn their caregiving behavior-monkeys/apes in captivity without parental contact do not know how to care for newborn infants

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How primatologists study behaviorBehavior: anything that involves acting in response to stimuli-not necessarily done consciously-may/may not be deliberate

Behavioral ecologyAll interconnected biological components* within an ecosystem evolved together

*components: animals, plants, microorganisms, etc.)

- the product of complex interactions between genetic and environmental factors

Social structure - important to us

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How primatologists study behaviorSocial structure - the composition, size, and sex ratio of a group-the result of natural selection

-large impact on individual and social interactions

Influences on social structure:Body sizeBasal metabolic rateDietDistribution of resourcesPredationActivity patterns

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How primatologists study behaviorSocial structure - the composition, size, and sex ratio of a group-the result of natural selection

-large impact on individual and social interactions

Influences on social structure:*Body size-body heat lost at surface -larger animals retain heat more efficiently

*Basal Metabolic RateMetabolism - at rest, the rate at which the body uses energy to maintain bodily functions -closely tied with body size

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Influences on social structure*Diet - likely evolved with body size and BMR-diet relates to behavior in terms of benefits measured against calories expended obtaining those calories

*Distribution of resources-feeding behavior determined by distribution of food resources and ease of accessE.g., matrilines (one male multiple female) break up into smaller groups while feeding

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Predation-behaviors in response to predatorsE.g., if high predation, smaller-bodied animals are likely to form larger communities

Life HistoriesLife history traits - characteristics or developmental stages a given species features/undergoes

E.g., shorter life histories are often more advantageous in marginal/unpredictable habitats (rapid reproduction)

...while longer-living animals are better suited to stable environmental conditions

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Influences on social structure

1. Primate grouping patterns1. Single female and offspring - Basic social unit (e.g., orangutans)

2. Monogamous family group - rare in nonhuman primates

3. Polyandrous - single female: multiple male (e.g., marmosets)

4. Single male and multiple female - single male: multiple female (e.g., gorillas)

5. Multiple males and multiple females - no stable bonds (e.g., baboons)

6. Fission-fusion - size and composition change relative to activities and patterns (e.g., chimpanzees)

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Reproductive strategiesBehavior favored by natural selection to increase an individual's reproductive success

K-selection - an adaptive strategy with fewer offspring and increased parental investment

E.g., birds, wolves, elephants

r-selection - more offspring coupled with less parental investment

E.g., mice

Primates are K-selected and the mother plays a larger role in raising offspring

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Primate reproductive strategiesPrimates are K-selected and the mother plays a larger role in raising offspring

Females - strategy: maximize available resources given energetic demands of being female

Males - strategy: produce as many offspring as possible

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