 Evolutionary game theory originated as an application of the mathematical theory of games to biological contexts, arising from the realization that frequency dependent fitness introduces a strategic aspect to evolution. Recently, however, evolutionary game theory has become of increased interest to economists, sociologists, and anthropologists--and social scientists in general--as well as philosophers. The interest among social scientists in a theory with explicit biological roots derives from three facts. First, the ‘evolution’ treated by evolutionary game theory need not be biological evolution. ‘Evolution’ may, in this context, often be understood as cultural evolution, where this refers to changes in beliefs and norms over time. Second, the rationality assumptions underlying evolutionary game theory are, in many cases, more appropriate for the modelling of social systems than those assumptions underlying the traditional theory of games. Third, evolutionary game theory, as an explicitly dynamic theory, provides an important element missing from the traditional theory. In the preface to Evolution and the Theory of Games, Maynard Smith notes that “[p]aradoxically, it has turned out that game theory is more readily applied to biology than to the field of economic behaviour for which it was originally designed.” It is perhaps doubly paradoxical, then, that the subsequent development of evolutionary game theory has produced a theory which holds great promise for social scientists, and is as readily applied to the field of economic behaviour as that for which it was originally designed.