Reciprocal altruism

Sociology

Repeated game

Natural (archaeology)

Punishment (psychology)

Altruism (biology)

Strong reciprocity

Social science

Group selection

Biology

Epistemology

Prosocial behavior

Philosophy

Paleontology

Artificial intelligence

Psychology

Economics

Microeconomics

Game theory

Anthropology

Kin selection

Computer science

Reputation

Mechanism (biology)

Inclusive fitness

Social psychology

Selection (genetic algorithm)

Creatures

Nature

Human cooperation is an evolutionary puzzle. Unlike other creatures, people frequently cooperate with genetically unrelated strangers, often in large groups, with people they will never meet again, and when reputation gains are small or absent. These patterns of cooperation cannot be explained by the nepotistic motives associated with the evolutionary theory of kin selection and the selfish motives associated with signalling theory or the theory of reciprocal altruism. Here we show experimentally that the altruistic punishment of defectors is a key motive for the explanation of cooperation. Altruistic punishment means that individuals punish, although the punishment is costly for them and yields no material gain. We show that cooperation flourishes if altruistic punishment is possible, and breaks down if it is ruled out. The evidence indicates that negative emotions towards defectors are the proximate mechanism behind altruistic punishment. These results suggest that future study of the evolution of human cooperation should include a strong focus on explaining altruistic punishment.

Altruistic punishment in humans