 Initially, it was thought that evolutionary game theory might provide an inroad into solving the equilibrium selection problem of traditional game theory. Although the fundamental solution concept of traditional game theory, the Nash equilibrium, had the desirable property of always existing for any game with a finite number of players and strategies, provided that mixed strategies were allowed, it had several deficencies. A Nash equilibrium was not guaranteed to be unique (sometimes even with uncountable many Nash equilibria existing), did not always seem to correspond to a reasonable outcome (see Hargreaves Heap and Varoufakis, 2004), and occasionally conflicted with people’s intuitions as to what ought to count as a rational outcome. In contrast, it could be shown that a completely mixed evolutionarily stable strategy was unique, that there were at most only a finite number of evolutionarily stable strategies, and that several intuitive definitions of evolutionarily stability were equivalent to the original definition of Maynard Smith and Price.