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Unformatted text preview: Problems of Kinship Inclusive fitness theory—important in evolutionary psychology Altruism—organism incurs a cost to itself in order to benefit someone else Are there adaptations for providing benefits to others? YES, look at theories! [Inclusive Fitness Theory]—William D. Hamilton (1936-2000) • Recall the gist of Darwin’s Theory of Natural Selection: Individuals whose heritable traits are helpful to their own survival … [Hamilton’s Inclusive Fitness Theory] aka Kin Selection Theory Classical Darwinian Fitness : a trait’s effect on the Reproductive Success of its bearer Inclusive Fitness (aka: Hamilton’s Fitness) : Classical Fitness + a trait’s effects on the RS of its neighbors • E.g. if you’re helping your sister’s reproductive success, it’s added to your fitness • E.g. if you give a kidney to your sister, it has a larger impact on your inclusive fitness than if you gave it to your first cousin • As the degree of genetic relatedness gets lessened, your inclusive fitness is degraded [Hamilton’s Rule: rb > c] = Defines how a gene for altruism can spread. • r= genetic relatedness between actor and the recipient • b= fitness benefit (in terms of the recipient’s extra offspring production) • c= fitness cost (in terms of the actor’s loss of its own offspring) • Altruism can evolve if the fitness benefit to the recipient (b), weighed by its relatedness to an actor (r), outweighs the fitness cost to actor (c). E.g. rb > c • Altruism at the individual level is actually selfishness at the gene level. • Kin selection includes parental care (special case of altruism towards genetic relatives) as well as altruism towards non-descendant kin. [Theoretical Implications of Hamilton’s Rule] • Evolved psychological mechanisms for each type of kinship relationship • For an adaptation to evolve, it must follow 1) Parenting —“special case” of evolved kinship adaptations 2) Sibship —cooperation and competition among siblings—genetic relatedness of . 50 a. They can compete for access to mates (E.g. two men can become intrasexual rivals for the same woman). So if your brother gets the woman, he is only passing on .25 of your genes! So you’re only related to your nephew (.25) but if you succeed in mating with the woman, you’re related to your son (.50) so it is to your advantage....
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- Spring '08
- Evolutionary Psychology, Kin selection, Inclusive fitness, Genetic relatedness, kin Kin group