In The Evolution of Cooperation, Axelrod and Hamilton (A&H) provide a game theoretic approach to the evolution of reciprocal altruism (cooperation). They argue that because Tit-For-Tat (TFT) is robust, stable, and initially viable, it can be used to explain how reciprocal altruism evolved in nature. There are three important issues regarding A&H’s approach to which the author responds. First, Nowak and Sigmund challenge the robustness of TFT by arguing that a strategy of Win-Stay, Lose-Shift (WSLS) can outperform TFT. Second, although A&H use clustering to account for the initial viability of TFT, they owe an explanation of how a cluster of TFTs could arise in the first place. Finally, A&H account for the stability of TFT by assuming, without empirical or theoretical support, that the individuals who interact have a sufficiently large probability of meeting again. The author will respond to these three issues in order to improve and extend A&H’s approach to the evolution of cooperation.



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