Evolution and Negative Reciprocity

Abstract

We offer a theoretical explanation of negative reciprocity or vengeance, i.e., the human desire to harm those who have harmed us. Our model shows how negative reciprocity can be sustained by the coevolution¹ of genes that determine the capacity for vengeance and group memes (e.g., social norms) that regulate its expression. The model begins with a standard free-rider game that captures, simply and directly, a personal cost incurred to reap social gains. The model shows that a taste for vengeance realigns incentives and supports a socially efficient equilibrium, but that by itself the taste for vengeance is not evolutionarily viable. We then show how groups of individuals can use low-power sanctions (or simply status changes) to enforce a particular norm on the proper degree of vengeance. The main result is that actual behavior will typically fall short of the norm, but selection across groups will adjust the norm so that actual behavior maximizes the fitness of group members.

See Dawkins (1976), Boyd and Richerson (1985), and Durham (1991).