Cooperation and Conflict in the Light of Kin Recognition Systems

Genetic relatedness is central to the problems of social evolution. Whenever individuals interact nonrandomly with respect to genotype, their actions may have indirect fitness consequences. Although population structure affects the frequency of interactions among relatives, kin recognition systems can help optimize behavior to the advantage of the actor's genetic posterity. Here, we review the functional and mechanistic foundations of kin recognition systems and demonstrate their effects on cooperation and conflict in a number of different species, devoting special attention to the case of Homo sapiens. We conclude by developing several testable hypotheses about the impact of kin recognition on social behavior.