Kin Selection and Relatedness

The theory of inclusive fitness, sometimes called kin selection, describes how selection operates when an individual's behavior affects fitnesses of others in addition to its own. Its key insight is that individuals will evolve to act as if they value effects on their interactants' fitnesses according to the degree of genetic relatedness between them, relatedness being the degree of allele sharing above random expectation. Kin selection is important because it can explain altruistic behavior, such as in workers of the social insects. However, it can also explain selfish behaviors and is important for understanding conflicts between individuals.