Life Science 15: Concepts and IssuesLecture 7: Kindness to our kin1/31/12I. Intro to kin selection: fitness vs. inclusive fitnessII. Hamilton’s RuleIII. RelatednessIV. Kin recognitionAustralian social spiders: increase reproductive success by allowing her babies to suck her dry and kill her- so that they can liveQ: Why is these so much kindness in the world? And could we engineer bit more cooperation when needed?Developing our theory of kindness:- Kindness:1. shared genes2. reciprocity (likely to see favor returned)1. Because gene X in you causes you to act in such a way that you increase the reproductive success of other individuals that carry gene X. (Shared genes/ Kin selection)2. Because gene Y in you causes you to help other people who will return the favor, thereby benefiting gene Y. (Gene Y buffers itself from an uncertain future by storing goodwill in others.) (Reciprocal Altruism)Genes are instructions for how to build the body, including the brain structures that give you pleasure and pain, and motivations to do (or not do) things.- genes that cause their carriers to pass on more copies increase their market shareTwo ways a gene can increase its market share:1. direct fitness: increase number of offspring you produce2. indirect fitness: increase number of offspring my kin have; they also may carry many of my genes- this is why we see kindness to kinInclusive fitness= direct fitness + indirect fitnessHow much do we expect individuals to help various relatives?- B*r – C > 0- As long as it is greater than 0, evolution will favor it- B is the benefit to relative- r is the coefficient of relatedness (0.0 to 1.0)- C is the cost to the individual- r = 0.5 for a sibling- r = 0.25 for a cousinFor situations in which this equation is true, we expect the “kind” act to occurThis is called: Hamilton’s Rule.Can we actually use this in nature?- greater r = more likely to see kindnessBelding’s Ground Squirrels:- yell sometimes when a predator approaches- hide always when they hear a yell- 10% of predator attacks end with a dead squirrel- 50% dead were the ones yelling- male squirrels relocate at maturity, and females don’to which squirrels are making the alarm calls? Oldest females: most related kin in community- Hamilton’s Rule can help predictions in nature- The more kin a squirrel has nearby, the more it will act “altruistically”‘r’ is a measure of the proportion of our genes we have in common with our relatives.Rules for calculating ‘r’:1. up up up, down down downa. never reverse directions on a path2. all paths are created equala. don’t forget a pathway3. multiply within, add between pathsAltruism requires kin recognition:- how do we do it?o Spatial association (treat those around you as kin)o Social association (treat those from childhood as kin)o Phenotype matching (treat those who resemble you as kin)Suppose you capture an old female Belding ground squirrel and move her to a new neighborhood far away…- What happens? Will she make alarms?o Yes- maladaptive behavior, she still does what she is evolved to doo Mismatch between world evolved in and new world Ex. Humans (hunter-gatherers - now food is readily available, so weight increases)The transplanted squirrel result has HUGE implications for your life and the study of human behavior in general.Genes code for behavioral “rules of