 Pitting a full range of stochastic strategies of this type against each other in a computerized tournament, using replicator dynamics in the manner of Axelrod and Hamilton (1981), Nowak and Sigmund trace a progressive evolution of strategies. Computer simulation shows imperfect All Defect to be an early winner, followed by Imperfect Tit for Tat. But at that point dominance in the population goes to a still more cooperative strategy which cooperates with cooperation 99% of the time but cooperates even against defection 10% of the time. That strategy is eventually dominated by one that cooperates against defection 20% of the time, and then by one that cooperates against defection 30% of the time. A replication of the Nowak and Sigmund result is shown in  Figure 17.  Nowak and Sigmund show analytically that the most successful strategy in a world of noisy information will be “Generous Tit for Tat”, with probabilities of \(1 - ε\) and 1/3 for cooperation against cooperation and defection respectively.