Abstract
Reciprocity is a pillar of our understanding of how cooperation works. However, this paradigm has been challenged by Efferson et al (Efferson et al., 2024) who claim that repeated interaction is insufficient to support cooperation. The authors base their conclusion on a model in which reciprocators use a novel function to determine their response. They find that cooperation through repeated interaction breaks down. I point out here that the collapse of cooperation is not the result of the novel strategy set. Instead, it is a standard result in models of cooperation when a benign environment allows drift towards undiscriminating strategies. I show how and when introducing an element of defection into a cooperative environment provides selection for the maintenance of discrimination. Discriminating strategies can resist invasion by strategies that would exploit undiscriminating cooperation. In consequence, cooperation is stabilized. I conclude that Efferson et al.’s results can readily be explained by existing theory and that repeated interaction can support cooperation without additional processes such as between group competition.
Competing Interest Statement
The authors have declared no competing interest.