In Chapter 12, Dawkins expands the concept of cheaters as Evolutionarily Stable Strategies. Take, for example, birds picking parasites off each other. The bird who receives the service without helping others in return is labeled a cheater and the birds who play by the rules remember that, becoming the “grudger.” The grudger stops helping the cheater, and the cheater loses out. It’s the Prisoner’s Dilemma, but in evolution. Mutual cooperation is the best strategy in this situation, but only if the majority of the group cooperates. In a situation where only the minority cooperates, the cooperators would be worse off and the cheaters would be better off. Mutual cooperation, however, is most beneficial for everyone involved, so it becomes the Evolutionarily Stable Strategy. The game of evolution is a nonzero sum game, meaning that there does not have to be one winner. Both sides can win. Dawkins argues that any game can become a nonzero sum game if its repeated enough times.