Reciprocal altruism

In evolutionary biology, reciprocal altruism is a behaviour whereby an organism acts in a manner that temporarily reduces its fitness while increasing another organism's fitness, with the expectation that the other organism will act in a similar manner at a later time.

The concept was initially developed by Robert Trivers to explain the evolution of cooperation as instances of mutually altruistic acts. The concept is close to the strategy of "tit for tat" used in game theory.

In 1987 Trivers told a symposium on reciprocity that he had originally submitted his article under the title "The Evolution of Delayed Return Altruism", but reviewer W. D. Hamilton suggested that he change the title to "The Evolution of Reciprocal Altruism". Trivers changed the title, but not the examples in the manuscript, which has led to confusion about what were appropriate examples of reciprocal altruism for the last 50 years. In their contribution to that symposium, Rothstein and Pierotti (1988)^[1] addressed this issue and proposed new definitions concerning the topic of altruism, that clarified the issue created by Trivers and Hamilton. They proposed that Delayed Return Altruism was a superior concept and used the term pseudo-reciprocity in place of DRA. For some reason, the paper by Rothstein and Pierotti did not catch hold, but it remains one of the best examinations of the relationship between altruism and kin selection. Rothstein and Pierotti also explain why Trivers' examples of Reciprocal Altruism are actually examples of delayed return altruism.