Recent studies suggest that allowing individuals to choose their partners can help to maintain cooperation in human social networks; this behaviour can supplement behavioural reciprocity, whereby humans are influenced to cooperate by peer pressure. However, it is unknown how the rate of forming and breaking social ties affects our capacity to cooperate. Here we use a series of online experiment...

The evolution of multicellular life requires cooperation among cells, which can be undermined by intra-group selection for selfishness. Theory predicts that selection to avoid non-cooperators limits social interactions among non-relatives, yet previous evolution experiments suggest that intra-group conflict is an outcome, rather than a driver, of incipient multicellular life cycles. Here we rep...

The threat of free-riding makes the marshalling of cooperation from group members a fundamental challenge of social life. Where classical social science theory saw the enforcement of moral boundaries as a critical way by which group members regulate one another's self-interest and build cooperation, moral judgments have most often been studied as processes internal to individuals. Here we inves...

A challenge for evolutionary theory is to understand how cooperation can occur in the presence of competition and cheating, a problem known as the tragedy of commons. Here I examine how varying the fitness returns from reproductive competition or cooperation affects the negative impact of competition on a social group. Varying linear returns does not affect the impact of competition. However, d...

Précis This debate article highlights the challenges of health situation in Iran and some influencing or relevant factors such as health sector, welfare system and social protection, social exclusion and civil society from the viewpoint of an international partner. Some advanced experiences in Iranian health system and the manner of system for international cooperation have also been discussed.

Cooperation in the face of moral hazard is a critical factor in economic development. Existing research on institutional support for cooperation has primarily focused on the role of contract enforcement in limiting the incentives for cheating. In contrast, we focus on the need for a social safety net to permit extensive cooperation. Starting from a basic prisoner’s dilemma model, we introduce u...

Cooperative behavior can be observed widely in our society. An important aspect of cooperation is that people can maintain mutual cooperation even if they are faced with social dilemma, which means the situation that people fail to cooperate although entire cooperation gives better payoff to everyone. Several mechanisms are pointed out to be important to overcome the social dilemma, and recipro...

The authors examined preschoolers' aggressive and cooperative behaviors and their associations with social dominance. First and as predicted, directly observed aggressive interactions decreased across the school year, and same-sex aggression occurred more frequently than cross-sex aggression. Next, the authors examined the relation between aggression and reconciliation, cooperation, and social ...

Often the selfish and strong are believed to be favored by natural selection, even though cooperative interactions thrive at all levels of organization in living systems. Recent empirical data shows that networks representing the social interactions between people exhibit typically high average connectivity and associated single-to-broad-scale heterogeneity, a feature which precludes the emerge...

Cooperating with others often entails some sacrifice of one's own material interests. Many theories of reciprocity and cooperation thus assert a social-material tradeoff. In these theories, people reciprocate cooperation when they prioritize how they treat others and how others treat them. They do not reciprocate cooperation when they prioritize their own material well-being. We challenge this ...