Kin selection and relatedness

Kin selection occurs when an individual’s behavior affects the fitnesses of others, usually relatives, that will transmit the behavior non-randomly. It is often analyzed with Hamilton’s inclusive-fitness rule. Its key insight is that individuals will evolve to act as if they value effects on their interactants’ fitnesses proportional 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.