Societies comprise aggregations of individuals interacting cooperatively with one another, but it is not immediately clear why such systems are not undermined by free-riders that accept cooperative acts while giving little or nothing in return. There are several ways in which cooperation can emerge and remain stable within societies despite self-interest. Kin selection may help explain much intraspecific cooperation, but it is not the only mechanism, and sometimes cooperation can be maintained by a complex interplay of several types of interaction, including reciprocity, partner choice, and the threat of punishment.

Altruism, By-product mutualism, Cooperation, Kin selection, Prisoner's dilemma, Pseudoreciprocity, Public goods, Punishment, Reciprocity, Social evolution
Department of Biology

Sherratt, T, & Wilkinson, D.M. (D. M.). (2009). Cooperation and Sociality. In Encyclopedia of Animal Behavior (pp. 396–401). doi:10.1016/B978-0-08-045337-8.00113-3