Theoretical Aspects of the Evolution of Human Social Behaviour

Three paradigms for the study of the evolution of behavior are reviewed. The first is kin selection, originally seen as an explanation for the evolution of altruistic behavior among relatives. This leads to the concept of inclusive fitness as a measure of an individual's contribution to subsequent generations. The second paradigm involves the calculus of fitness payoffs resulting from games between individuals that behave differently or between one bahavior and all possible alternatives. This economic approach produces the notion of evolutionarily stable strategy (ESS) as a mode of behavior that is in some sense optimal. Finally, we discuss gene-culture coevolutionary theory according to which genetic and cultural transmission, in combination with natural selection, produce the population dynamics of behavioral variation and resulting correlations among relatives. Examples discussed include avoidance of inbreeding, lactose absorption and mile drinking, sign languages and deafness, bias against daughters and the population sex ratio, measured IQ, and left- and right-handedness. Unlike inclusive fitness ofr game-theoretic analyses, gene-culture coevolutionary approaches do not involve optimality reasoning or assumptions of rationality among actors. In this sense it is a natural extension of classical population analysis to include non-genetic familial and social transmission. To appear in World Science Report.