PSYC 3P37 Lecture Notes - Lecture 8: Infant Mortality, Parental Investment
Document Summary
Many aspects of family relationships might be understood by considering the degrees of relatedness between relatives. Can calculate degree of relatedness, r, between any two genetic relatives. Levels of relatedness (0 <= r <= 1) by relationship : 1 = self (also identical twin, . 5 = siblings; parent & offspring, . 25 = aunt/uncle & nephew/niece; grandparents , . 125 = first cousins; various others grandchild; half-siblings. Hamilton (1964) showed that altruism toward kind could be favored by natural selection. It was already understood that parental investment could sometimes by favored, but other forms of kin altruism weren"t previously understood. Genetically based tendency for altruistic behavior will be selected as long as it produces altruistic acts for which rb > c (r. = degree of relatedness, b = benefit to recipient, c = cost to donor) Would expect individuals to be more readily inclined to be altruistic toward siblings than toward half siblings, toward cousins that random members of population, etc.