Diverse ontogenies of reciprocal and prosocial behavior: cooperative development in Fiji and the United States.

Contingent reciprocity is an important foundation of human cooperation, but we know little about how reciprocal behavior develops across diverse societies, nor about how the development of reciprocal behavior is related to the development of prosocial behavior more broadly. Three- to 16-year-old children were presented with the opportunity to control the allocation of real food rewards in a binary-choice cooperative dilemma. Within dyads children alternated making choices across multiple trials, and reciprocal behavior emerged in three diverse populations (rural Fijian villages, and urban communities in both Fiji and the United States) by age 7-8. There was more societal variation in prosocial behavior than in reciprocal behavior, and there were more substantial differences between Fijians and Americans than between rural and urban populations. This suggests that the development of prosocial behavior is not driven entirely by the development of reciprocity, and differences in prosocial behavior across rural Fijians and urban Americans may not be due only to differences across rural and urban populations.