On the coevolution of social norms in primitive societies

We study the evolutionary origin of a social norm of the kind "cooperate frequently and share fully" observed in modern hunter-gatherers. In order to do this, a two-stage game in which a pie has first to be produced and then divided is proposed. We assume that the bargaining rule is sensitive to investment behavior and to the degree of property rights protection. We show that, when a unique stochastically stable outcome exists, a norm of investment and a norm of division coevolve supporting the efficient investment profile and the egalitarian distribution of the surplus, respectively. The conditions needed for norms to coevolve depend on whether property rights over the fruits of one's own independent investment are secured or not.