Reciprocal altruism

The concept was initially developed by Robert Trivers to explain the evolution of cooperation as instances of mutually altruistic acts.

While Trivers adopted the new title, he retained the original examples, causing confusion about reciprocal altruism for decades.

Hamilton, who developed mathematical models for predicting the likelihood of an altruistic act to be performed on behalf of one's kin.

[1] If chances of meeting another reciprocal altruist are high enough, or if the game is repeated for a long enough amount of time, this form of altruism can evolve within a population.

This is close to the notion of "tit for tat" introduced by Anatol Rapoport,[3] although there still seems a slight distinction in that "tit for tat" cooperates in the first period and from thereon always replicates an opponent's previous action, whereas "reciprocal altruists" stop cooperation in the first instance of non-cooperation by an opponent and stay non-cooperative from thereon.

Condition number five is required as otherwise non-altruists may always exploit altruistic behaviour without any consequences and therefore evolution of reciprocal altruism would not be possible.

Condition number six is required to avoid cooperation breakdown through forward induction—a possibility suggested by game theoretical models.

[7] A key requirement for the establishment of reciprocal altruism is that the same two individuals must interact repeatedly, as otherwise the best strategy for the host would be to eat the cleaner as soon as cleaning was complete.

However, if Randall's claim that hosts sometimes chase off possible dangers to the cleaner is correct, an experiment might be constructed in which reciprocity could be demonstrated.

An explanation in terms of altruistic behaviors given by Trivers:[1] It has been shown that predators learn specific localities and specialize individually on prey types and hunting techniques.

Alarming another bird by giving a warning call tends to prevent predators from specializing on the caller's species and locality.

After analyzing the results, there was not significance evidence for kin selection; the presence of extra-pair offspring did not affect the probability of help in nest defense.

One of the studies in vervet monkeys shows that among unrelated individuals, grooming induce higher chance of attending to each other's calls for aid.

[23] This would demonstrate vervet monkey's grooming behavior as a part of kin selection since the activity is done between siblings in this study.

[24] This reciprocal altruistic behavior has been exploited by techniques designed to eliminate B. tryoni, which are fruit fly pests native to Australia.

[25] Examples of reciprocal altruism in humans include helping injured individuals, sharing food, tools, or knowledge,[26] and providing assistance in crises with the expectation of future aid.

In social interactions, individuals often engage in direct reciprocity, such as returning favors or lending resources with an implicit understanding of future repayment.

Indirect reciprocity is also observed,[27] where individuals help others based on reputation, encouraging mutual cooperation within a community.

Economic and political systems rely on reciprocal altruism through trade agreements, diplomatic alliances,[28] and social contracts, where long-term benefits outweigh short-term costs.

Additionally, studies in game theory, such as the Prisoner’s Dilemma, illustrate how cooperative behaviors emerge and stabilize when individuals recognize the advantages of mutual support.