Evolution of cooperation by reciprocity has been studied using two-player and n-player repeated prisoner’s dilemma … cooperation when less generous, and better at maintaining a long-term cooperation in the presence of rare defectors when more …

facilitate and obstruct cooperation in a repeated prisoners' dilemma game. In finitely repeated games a player who cares only for … infinitely repeated games with two emotional players less patience is required to sustain cooperation. However, emotions can also … obstruct cooperation if they make the players unwilling to punish each other, or if the players become hostile when punished. …