Extortion and Evolution in the Iterated Prisoner’s Dilemma

nonexclusive right to make this work available for noncommercial, educational purposes, provided that this copyright statement appears on the reproduced ma-terials and notice is given that the copying is by permission of the author. To dis-seminate otherwise or to republish requires written permission from the author. The Prisoner’s Dilemma is a two player game where playing rationally leads to a suboptimal outcome for both players. The game is simple to analyze, but when it is played repeatedly, complex dynamics emerge. Re-cent research has shown the existence of extortionate strategies, which al-low one player to win at least as much as the other. When one player plays such a strategy, the other must either decide to take a low payoff, or ac-cede to the extortion, where they earn higher payoff, but their opponent receives a larger share. We investigate what happens when one player uses this strategy against an “evolutionary ” player, who makes small changes to her strategy over time to increase her score, and show that there are cases where such a player will not evolve towards the optimal strategy of giving in to extortion