Chapter 8: Problems of Kinship PDF

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Evolutionary Psychology: The New Science of the Mind (6th edition) by David M. Buss...

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Problems of Kinship

● if everyone loved everyone equally, there would be no favoritism. u would give ur res to anybody. it’s crazy cuz ppl differ in their genetic relatedness 2 others according 2 inclusive fitness theory !! (444) ● an indivs relatives r all vehicles of fitness, but they differ in value (445) ○ we r related 2 our parents/children/sibs by 50% ○ 25% to our grandparents n grandchildren/half sibs/uncles/aunts/nieces/nephews ○ n 12.5% on avg 2 our first cousins ● sel will favor mechs 4 helping ourselves 2x as much as we help a brother ○ but a brother is 2x as related 2 us than a nephew n thus would ge 2x the help ○ a bro struggling will benefit more than a wealthy bro ○ altruism can evolve under conditions of low/no relatedness ● one straightforward prediction from inclusive fitness theory: sel will often favor the evo of mechs 2 help close kin more than distant kin n distant kin more than strangers

Theory and Implications of Inclusive Fitness hamilton’s rule—the technical formulation of fitness theory. favoritism expressed by parents towards their children is cuz they r the vehicles of certain copies of their genes. then u gotta consider cooperation, conflict, risk taking, inheritance of wealth, n grieving (446) Hamilton’s Rule ● altruism is defined by two conditions: (1) incurring a cost to the self to (2) provide a benefit 2 the other person ● hammy (1964) asked, under what conditions would such an altruistic gene evolve? ○ his insight was that it could evolve if the benefit was greater than the cost ○ “nat sel favors mechs 4 altruism when c < rb” (447) ■ c = cost 2 the actor ■ r = degree of genetic relatedness btween actor n recipient ■ b = benefit 2 recipient ○ basically if the benefits to a 0.5 kin member are more than 2c or if the benefits to a 0.25 kin member are more than 4c, n so on ○ genetic relatedness: the probability of sharing a particular focal gene w another indiv over n above the avg pop frequence of the gene ● hammy’s rule defines the selection pressure 2 which genes for altruism r subject ● any traits that enter the pop thru mutation that fail hammy’s rule will be selected against ○ sometimes called evolvability constraint cuz only genes that meet the conditions of hammy’s rule can evo (446) ● bro hammy’s theory of inclusive fitness is deadass the most important theoretical revision of darwin’s theory of nat sel in the past century bro (448)

● hammy’s formulation of inclusive fitness also show that altruism far removed from personal repro could easily evolve Theoretical Implications of Hamilton’s Rule the most important implication of hammy’s theory of inclusive fitness is that psychological adaptations r expected 2 have evolved 4 diff types of kin relationships. nun in hammy’s theory *requires* that any kinship mechs necessarily evolve. remember the kin conflicts ok ! (448-9) siblings have unique adaptive probs ! they can b a phat social ally but also r competitors 4 parental res. so ofc there’s conflict. a study in rural ethiopia found tho that the wealthier the parents were, the higher the competition btween sibs !! (449) ● sulloway (1996, 2011) proposed that the adaptive probs imposed by parents on bbs will create diff “niches” 4 children depending on birth order! ○ first borns r favored n likely 2 maintain the status quo ○ 2nd borns have little 2 gain by supporting but have everything 2 gain by rebelling ○ the youngest might receive more investment cuz they’re the last direct vehicle ● salmon n daly (1998) found support ! (450) ○ mid borns score lower in meas of family solidarity than eldest n youngest ○ mid borns r also less likely to... ■ name a genetic relative as the person they feel closest ■ assume genealogy ■ have positive attitudes towards their fam ■ help a fam member who needs help ● middle kids might receive less total investment even if parents treat all their bbs equally ○ eldest receive all their investments early in life ○ youngest receive all investments after the older sibs leave the house half sibs r only related 2 us by 25%. in a study on squirrels by holmes n sherman (1982), full sisters r way more likely than half sisters 2 cooperate in the mutual defense of their young ● “in human prehistory it was a virtual toss-up whether successive bbs of the same woman r full or half sibs n the distinction btween (r = 0.5) and (r = 0.25) is by no means trivial when the decision 2 cooperate or 2 compete is a close call” - daly n friends (1997) (451) ● a study in finland found that full sibs had considerably more contact than half sibs ○ these findings suggest that, among sibs, higher lvls of genetic relatedness importantly predict investment, supping hammy’s theory of incfit there’s a hypo that menopause evolved as a means of ceasing direct repro in order 2 invest in children n then grandchildren, now what has become known as the “grandma hypothesis” x culturally, post-meno women contribute hella 2 their gkids daly et al (1997) outline a set of hypos ab the universal aspects of the psych of kinship. first they suggest that ego centered kin terminology will be central—all kin will b classified in ref 2 a focal indiv, such as “my mom is not the same as ur mom” or “my sis is not the same as ur bro” (452) ● second, all kinship systems will make critical distinctions along the lines of sex (f and m) ○ basically the sex of the kinmember is important 2 the adaptive probs faced so it’s

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expected that the kin systems would differentiate based on sex third, generation! it’s usually asymmetrical ○ early on we learn n depend on our parents ○ w advancing age, we become more valuable while parents become less useful fourth, kin relationships will b universally arrayed on a dimension of closeness which will b highly linked w genetic relatedness fifth, the degree of cooperation n solidarity between kin will b a function of their degree of genetic relatedness; we tend 2 turn 2 close kin when in need rather than distant kin sixth, the elder members of an extend kin family will encourage the younger members to behave more altruistically and cooperatively toward collateral kin ○ imagine an older man w a son, sister, n his sister’s son ○ his sister;s son is related to him by 0.25 ○ but from his own son, he’s only related by 0.125 seventh implication of inclusive fitness theory is one’s position within an extend kin network will be the core components of the self-concept ○ “son of ___” or “sister of ___” eight implication of inclusive fitness theory is that despite the diffs across cultures ab exact terms 4 kin, ppl everywhere will b aware of who their “real” relatives are lastly, kinship terms will b used 2 persuade n influence other ppl even when no actual kinship is involved (454) ○ “hey brother” or “hi baby”

Empirical Findings That Support the Implications of Inclusive Fitness Theory Alarm Calling in Ground Squirrels in a species of ground squirrels, if a squirrel detects danger, it’ll make a loud alarming sound 2 alert the other squirrels. the other squirrels get 2 find safety but the alarm-squirrel puts itself in a vulnerable position !! why ! (455) ● here’s some hypotheses 2 help explain this act of altruism! ○ predator confusion hypothesis: the alarm might b used 2 confuse the predator since the squirrels will go in a mad scramble ○ parental investment hypothesis: even tho the alarm-squirrel is at greater risk, maybe the children r more likely 2 survive as a result. it’s a parental thing! ○ inclusive fitness hypothesis: even tho the alarm-squirrel might suffer premature death, the alarm-squirrel’s family (literally all relatives) benefit bc of safety (456) ● so predator confusion hypo is wrong thx 2 paul sherman ● apparently females give the calls more than males do which is consistent w 2 & 3 ○ do females still call when they dont have children (but have other relatives)? yes ! ● these findings supp tohe hypo that altruism can evolve thru inclusive fitness.

Kin Recognition and Kin Classification in Humans providing aid 2 kin first reqs the ability 2 recognize them. early association—exposure 2 kin in infancy—is a key cue primates use. assc in childhood also encourages incest-avoidance (457) ● another kin recognition mech that has g empirical supp is that we can detect them by odor ● all cultures have kin classification systems—specific terms that describe types of kin ● jones id’ed a “universal grammar” governing all systems of kin classification, which consists of 3 innate “primitives” of social cognition: ○ genealogical distance: how close or distant the kin are ○ social rank: relative age, w the older being higher ranked than the younger ■ high ranking prolly provide more help than low ranking ○ group membership: diff clumps of kin, like maternal/paternal or same sex/opp sex ● all this provides a means of id’ing indivs of diff “kinship value” 2 us which is important 3 altruism (458) ● evidence also suggest that humans can detect kinship among strangers/nonrelated ppl ● detecting kinship clusters in others might b critical 4 solving important adaptive probs: ○ knowing who is likely 2 b allied w whom if hostels break out ○ who not 2 antagonize cuz they have formidable kin in close proximity ○ who might b “exploitable” cuz they have few kin protectors nearby ● humans have at least 4 ways of id’ing kin: (1) association, (2) odor, (3) kin classification thru universal grammar, n (4) facial similarity/phenotypic resemblance (459) Patterns of Helping in the Lives of Los Angeles Women ● predictions of described instances of receiving/giving help ○ among kin, helping will increase as a function of genetic relatedness ○ among kin, helping will increase as the recipient’s repro val increases ● the % of instances of helping fall into 3 categories of kinship: 50%, 25% and...