The evolution of context-dependent altruism

Altruism, in which individuals sacrifice some of their own reproduction to help others, can evolve if it is preferentially directed towards relatives. One mechanism by which organisms can recognize relatives is through phenotypic similarity. Under classic theory, the threshold relatedness at which altruism becomes beneficial depends on the overall relatedness of the population. This suggests that natural selection may favor context-dependent strategies, in which an individual compares a potential partner's phenotypic distance to that of the overall population in deciding whether to help them. We use computer simulations to determine the circumstances under which context dependence is actually favored over simple hard-coded strategies.