Abstract

Ernst Fehr and his collaborators have argued that traditional explanations of human cooperation cannot account for strong reciprocity. They provide substantial empirical evidence that strong reciprocity is an important phenomenon that cannot be explained by the traditional models of kin selection or reciprocal altruism. In this note, however, I argue that it will be difficult to test specific adaptive explanations of strong reciprocity because it is apparently unique to humans. Consequently, it is difficult to employ the comparative method, which is one of biology’s best tools for testing adaptationist claims.