Can War Foster Cooperation?

Altruism-benefiting fellow group members at a cost to oneself-and parochialism-hostility toward individuals not of one's own ethnic, racial, or other group-are common human behaviors. The intersection of the two-which we term "parochial altruism"-is puzzling from an evolutionary perspective because altruistic or parochial behavior reduces one's payoffs by comparison to what one would gain by eschewing these behaviors. But parochial altruism could have evolved if parochialism promoted intergroup hostilities and the combination of altruism and parochialism contributed to success in these conflicts. Our game-theoretic analysis and agent-based simulations show that under conditions likely to have been experienced by late Pleistocene and early Holocene humans, neither parochialism nor altruism would have been viable singly, but by promoting group conflict, they could have evolved jointly.

In summary, then, the circumscription theory in its elaborated form goes far toward accounting for the origin of the state. It explains why states arose where they did, and why they failed to arise elsewhere. It shows the state to be a predictable response to certain specific cultural, demographic, and ecological conditions. Thus, it helps to elucidate what was undoubtedly the most important single step ever taken in the political evolution of mankind.