Using a social orientation model for the evolution of cooperative societies

We utilize evolutionary game theory to study the evolution of cooperative societies and the behaviors of individual agents (i.e., players) in such societies. We present a novel player model based upon empirical evidence from the social and behavioral sciences stating that: (1) an individual's behavior may often be motivated not only by self-interest but also by the consequences for others, and (2) individuals vary in their interpersonal social tendencies, which reflect stable personal orientations that influence their choices. Alongside the formal player model we provide an analysis that considers possible interactions between different types of individuals and identifies five general steady-state behavioral patterns. We present evolutionary simulations that ratify previous findings on evolution of cooperation, and provide new insights on the evolutionary process of cooperative behavior in a society as well as on the emergence of cooperative societies. Our main experimental result demonstrates that in contrast to previous common knowledge, increasing mutual reward or mutual punishment in the Prisoner's dilemma game does not result in the same type of cooperative society: while increasing reward does increase the society's cooperativeness level, increasing mutual punishment does not.