Life Science 15: Concepts and IssuesLecture 8: Friend and foe are fluid categories2/2/12I. evidence of kin selectionII. cooperation is rare in the animal worldIII. certain conditions are conducive to altruism among non-kinIV. reciprocal altruism in your lifePredictions of kin selection:1. MURDER: more non-relatives killed than relatives among cohabitants2. INFANTICIDE: children in step-families are injured or killed more frequently than those living with their biological parentsa. Step parents are 100x more likely to kill step-children3. BEQUESTS: individuals will leave more of their estate to close kin than distant kina. Spouses, children are most likelyAmong unrelated individuals, selfishness is the rule and kindness is the exception.- bicycle sharing programso stolen and broken, alwaysKindness:1. shared genes2. reciprocityAnimal friendship?- none- cooperation among non-kin in animal species is rare, almost nonexistent- only example: Vampire Batso suck blood for foodo 10% adults, 33% juveniles fail to find a meal on any given nighto bat will starve to death if it doesn’t eat for more than 2 consecutive dayso “full” bat sometimes regurgitates blood meal in hungry bat’s mouth who gets this ‘free lunch?’- bats are significantly more likely to give food to bats that have previously helped it- bats shun those who don’t help themCooperation is really rare in the animal kingdom.Conditions conducive to reciprocal altruism:1. repeated interactions2. high benefit to recipient relative to cost to the actor3. ability to keep tabs on people and punish cheatersWhat is the big impediment to kindness? (biological perspective)- freeloaderso vulnerable when you do something kind for another (fitness perspective)o cheater takes the favor and runso market share of cheater’s genes increaseso market share of altruist’s genes decreases- effective altruists can remember the cheatersWhat are some design features we would expect to see in the human brain?What skills should we be good at?1. we ought to excel at recognizing facesa. vampire bats: 100 individualsb. humans: thousands!2. we ought to be good at keeping track of cheaters3. we ought to be voracious consumers of social informationGossip, social information and protection against cheaters:- Why are our brains so good at keeping track of social info?- Why do we keep tabs on people we will never meet?o Our brains are built for a world where we encountered only a small number of people (about 100) and we may have needed any one of themHumans recognize faces, keep track of kindness/selfishness and live for a long time; this makes reciprocal altruism possible.Your avenues to enhancing cooperation:1. tinker with perceived costs and benefits2. distinguish cheaters and kind people3. reduce the perceived vulnerability of partners1. reduce perceived cost to other persona. accentuate the benefit you will receive from the cooperation2. facilitate the building of reputationsa. use honest signals that can’t be fakedb. keep track of and punish cheaters3. make the first step: giftsa.