An Evolutionary Model of Reciprocity

Despite the pervasiveness of reciprocal behavior, it has received little attention in the economic literature. In this paper, I consider an evolutionary model of reciprocity. The main findings of this paper are that evolution can support reciprocal behavior for the fraction of population, which is insensitive to the stakes involved, but is sensitive to the cohesiveness of the relationships. These findings match stylized facts learned from experimental and field studies of reciprocity.