A new study has suggested that a combination of repeated interactions and group competition synergistically contributes to fostering cooperation effectively, shedding light on the unresolved mysteries of human evolution. The study conducted by researchers from the Universities of Zurich, Lausanne, and Konstanz, challenges the prevailing explanations of cooperative behavior in human evolution.

“We have challenged the prevailing theory that suggests cooperative behavior prevailed due to repeated interactions alone. Our comprehensive theoretical analysis linked with the experiment shows that repeated interactions alone cannot explain the evolution of human cooperation,” said Ernst Fehr of the University of Zurich, the corresponding author of the study.

The research addresses the long-standing question of how pro-social, cooperative behavior could have evolved, prioritizing the benefit of the community over that of the individual. The prevalent theory suggests that cooperative behavior pays off in the long run due to repeated interactions, where individuals learn that cooperation leads to mutual benefits over time. However, the researchers found strong empirical evidence that people behave cooperatively even in non-recurrent and anonymous interactions, challenging the existing explanations.

In an experiment conducted among indigenous people in Papua New Guinea, resembling a trust game, the participants engaged in exchanges of money and had to decide whether to act selfishly or rather cooperatively. Charles Efferson of the University of Lausanne, the first author of the study, summarized the results, stating, “Repeated interactions create an incentive for cooperation within the group. However, this is a fragile state. Group competition, on the other hand, has a stabilizing effect on this fragile state.”

The study revealed that the migration of cooperative and non-cooperative individuals between groups weakens the cooperative groups, challenging the idea that groups with several team-oriented members fare better in competition and that general cooperation spreads because less cooperative groups die out.

“This is perhaps the most provocative result of our study, as it completely contradicts the mainstream,” added Ernst Fehr. Furthermore, the analysis showed that competition between cooperative groups weakens overall cooperation in the population, highlighting the complexity of the evolution of cooperation in human history.

The participants in the experiment were each given five monetary units in local currency, equivalent to half a day’s wages, and were divided into pairs for a one-time interaction, an anonymous sequential exchange. The experiment demonstrated that the simultaneous interaction of both mechanisms, “repeated interactions” and “group competition,” leads to a form of super-additive cooperation, explaining the cooperative behavior observed even in one-time interactions.