ABSTRACT
INTRODUCTION Few actions in human societies appear as ubiquitous as cooperative behavior. Nonetheless, from evolutionary perspective, cooperation remains something of a mystery. We can all recall scenarios in which cheating (i.e., noncooperative behavior) yields a higher payoff than cooperating. This paradox is formalized in game theory, a branch of economics imported into evolutionary biology by Maynard Smith and Price (1973). Game theory models situations in which the payoff to an individual is dependent on his own behavior plus the behavior of others.
