bioanth ch. 8 – Flashcards

most fundamental primate behavioral adaptation -hallmark of nearly all haplorhine and essential for nonhuman primate behavior research -want to know why they are social -study costs and benefits of group living and see how same evol. processes that promoted sociality in nonhuman primates may have caused emergence of humankind

modern approach to study nonhuman primate behavior

first researcher to immerse in life of animals for years to learn intimate details -this is norm for primatologists: grad students do 1-2 for thesis and some do field studies of 10+ years

paternity tests using DNA, studies of endocrine influences on behavior using hormones extracted from feces or urine, and studies of communication using sophisticated sound recording equipment

study conducted in zoo, lab, or other enclosed setting -good bc animals wont hide -can also manipulate group: intro new male -confirm and refine results of studies in the wild

conducted in large area that is enclosed or isolated in some way so the population is captive -animals can have territories, form own groups, forage for food -can follow kinship and generations -more natural pattern than in zoo but not as natural as wild

conducted in habitat in which primate naturally occurs -see patterns of behavior that evolved in response to enviro variabilities -can see various aspects of ecology like diet and influence on grouping patterns/social behavior -positional behavior: relationshipo bw locomotor morphology and physical environment -social interactions within and bw primate groups -problems: primatologist must accustom animals to presence, poachers can kill so area must be safe, activity in dense foliage is hard to see, hard to manipulate

all behaviors in wild have immediate causes: hunger, fear, sexual urges -the immediate (proximate) causes involve the hormonal, physiological reasons for the animal to act -behavior reflects deeper evolved tendencies over millions of years of natural and sexual selection for reproductive success (baboon mates bc of immediate impulse that are hormonal/social, but ultimately the urge to mate is deep/evolved strategy that arose thru natural selection to inc baboon's reproduction odds)

grouping pattern in which a primate species lives, including its size, and composition evolved in response to natural and sexual selection pressures -behavior can be seen as adaptation, one aspect of primate's phenotype (if aggression means more repro. success, than aggression is subject to evol. forces)

-females have lower reproductive potential and lower variance in reproductive output than males -females invest more time and energy on offpsring during gestation and offspring rearing than males do -by Darwinian sexual selection theory, females tend to be competed for by males rather than the other way -RESULT: expect females to prioritize gathering adequate food supplies for themselves and offspring, expect males to chase after them

social system in which females remain and breed in the group of their birth whereas males migrate -they dont migrate at maturity, males do -fems bond tightly -when they live together, form kinship and have more incentive to cooperate and limit competition over food resources -do territorial defense -more female affiliation, sit/groom

males remain in natal home range and females migrate -in chimp groups, fems very competitive, dont groom each other -high # of males in primate group related to predator risk

-some are aggressive to compete over females -have no paternal role other than contributing genes, could be harmful if involved

ranking of indiv primates in group that reflects their ability to displace, intimidate, or defeat group mates in contests -est early in life -immigrant males cant immediately be ranked higher, must rise -in male philopatric groups, male has to show maturity and dominate all over females -in lemurs, males arent dominant, females choose new mate, displacing them at food sources and choosing newly immigrated males; males dont do dominance games bc social dynamics are strongly influenced by high ranking females (BO$$)

-invest more time/energy in reproduction than males -dont compete for males, but have sexual selection bc must go thru gestation and all this shii bc offspring completely dependent on her -more likely to die bc less able to escape predators and suffer nutritional stress/disease -DOMINANCE: among chimps there was rank based on # surviving offspring; daughters of high ranking females also mature more rapidly than low ranking fems; form matrilineal kin groups where status may influence repro. success; choose more dominant male bc better health/access to food; offspring of dominant animals grow up to be high ranking -SEXUAL RECEPTIVITY SIGNALS: sexual receptivity is willingness to mate; make more attractive to males; body posture, tails over backs and shake heads from side to side, present rumps; during ovulation, the female rump may swell producing fluid filled odors and show she is ready/willing to mate and make males compete for her, inducing competition and confusion

why do groups form if evol. goal is individual mating success -access to mates -food -avoiding predators

-having multiple mates in area bc enhancing repro. success is main goal -many males often lose out due to time/energy to acquire female -when access is at stake, become more violent (baboons) -if males more aggressive, more sexual dimorphism bc females choose more aggressive one -species who sexual dimorphosize in body size live in polygynous groups -monogamous and solitary species are less dimorphic

multiple females live with either one or multiple males

-food competition leads to survival problems

yep

females have evolved strategies for coping with need to balance limited food supplies while avoiding predators with demands of mating and rearing offspring

most strepsirhine are solitary -females occupy indiv territories w/ dependent offspring who they defend by scent marking objects, but must locate males during breeding season -males occupy territories that overlap female territories and maintain exclusive mating access to all females and keep transient away -males use scent marking and calls to warn or intruders -when females live solitary lives, males must decide: defend them or share them -most do monogamy

social system where male and female live in pair bond for extended period of time like years -sometimes they secretly mate outside pair -best understood as female reproductive strategy bc est and hold territories and each territory is a single male to a resident female; so female tolerates presence of a male -sometimes males stick around to help w/ kid to ensure that they fathered the offspring -in this, males dont compete as much so sexual dimorphism is deemphasized (not much diff in gibbons)

-majority of haplorhine nonhuman primates live in groups of 1 or more males and more than one female in social system -characterized by complexity of social interaction -in some species sociality is with evol. or brains capable of remembering a long history of interactions w/ gorup mates (debts/favors owed) and strategizing -complexity influenced by social system; male in multimale group must use more complex tactics to get mates than male in monogamous male relationship

harems -one male lives with as many females he can monopolize -harem implies male control over females and is obsolte bc dates back from when primatologists didnt appreciate role that females play in mating system -these groups are actually driven by female choices -females also transfer bw groups so silverbacks are fearful and anxious that their female will leave them -sometimes a male attacks a male from another group to become the new resident male

showed that multitiered social system of gelada baboon, females bond to one another, and the male is simply hoping to be accepted by "his" females

male nonhuman primate can have as many females to himself as he can molopolize -downside: fend off other males who want to mate with his females -as # females in a group inc, it is impossible for a male to prevent other males from joining group -so as more males join, could be competition for who has priority of access: alpha males get most and excludes his rivals when females are in estrus

most complex -not cohesive, but temporary associations come together and split up repeatedly -animals travel in foraging parties of varying sizes -chimpanzees, bonobos, spider monkeys -have distinct home ranges and community membership within which members join and part unpredictably in temp. foraging units called parties -1 chimp can be in 3 parties or more -this social system evolved on reliance on ripe fruit in diet bc of patch and seasonal distribution of fruits in tropical forest and daily variation in fruit availability; females forage by themselves to optimize fruit access and males control access to females by forming bonds w/ one another

-1 female lives in a reproductive or social unit w/ multiple males -rare in nonhuman primates, more in birds; some marmosets and tamarins in New World tropical forests -sometimes males bond together and help female rear offspring; reproductive strategy by males -marmosets and tamarins are small and vulnerable; fems boost repro. output by producing twins, but twins weigh a lot, so males assist by carrying babies and is antipredator defense -males also opt to assist female to inc reproductive success; if 2 males, each has 50% chance of fathering -not everyone in group mates this way; some reproductively monogamous, but socially polyandrous w/ male helpers