Frozen Evolution. Or, that’s not the way it is, Mr. Darwin. A Farewell to Selfish Gene.

Organisms live in the real world, not in the world of idealized models. One of the basic differences between models and reality is the fact that the real world is always more or less unpredictable (stochastic) and errors happen there with a certain probability. An individual can, by mistake or accidentally, betray its opponent or, to the contrary, cooperate in error, or its behavior can be misinterpreted in the same way by the opponent. In the real world, Tit for Tat is not an optimal strategy and can be forced out of the population by other strategies. An example of a strategy that is more successful in the unpredictable real world is “Generous Tit for Tat”, sometimes also called “Firm but Fair” (Nowak & Sigmund 1992). This strategy forgives sporadic betrayal with a certain probability (30 %), i.e. it responds by cooperation in the next round of the game. If two bearers of the Tit for Tat strategy play against one another and one of them betrays by mistake, it launches a long series of mutual punishment and both opponents fail to profit. On the contrary, if this situation occurs for two bearers of the Generous Tit for Tat strategy or one Generous Tit for Tat bearer and one Tit for Tat bearer, the mutual punishment series will be terminated quickly as soon as the Generous Tit for Tat bearer responds to the betrayal by cooperation in the next round.