A large number of individuals are randomly matched into groups, where each group plays a finite symmetric game. Individuals breed true. The expected number of surviving offspring depends on own material payoff, but may also, due to cooperative breeding and/or reproductive competition, depend on...

We find that contrary to common perception, cooperation as equilibrium of the infinitely repeated discounted prisoner's dilemma is in many relevant cases not very plausible, or at least questionable: for a significant subset of the payoff-discount factor parameter space cooperation equilibria...