How evolution explains altruism

In the 1990s, Nowak and Karl Sigmund, building on work by Robert Axelrod, showed that the Prisoner’s Dilemma, played over and over, could describe cycles of behavior in which strategies of selfishness (“Always Defect”) are beaten out by cooperation (“Tit for Tat”), then overtaken by even more cooperative behavior (“Generous Tit for Tat,” summarized as “Never forget a good turn, but occasionally forgive a bad one”), only to be invaded once more by egoists until the cycle begins anew. These “evolutionary dynamic” models, made more realistic by introducing an element of randomness, demonstrate that under the right conditions, competition can lead to teamwork. They also show how fragile that balance can be.

In “SuperCooperators,” Nowak argues that two of his mechanisms, indirect reciprocity and group selection, played an important role in human evolution. Think of a proto-simian trying to figure out whether to trust another in an exchange: Should I provide sex now for food and protection later? The proto-simian may have observed the behavior of its prospective partner, or it may not have; chances are good that others have, though. Reputation becomes important. The proto-­simian evolves into a hominid, with a bigger brain allowing for more precise communication about reputation. Moral instincts evolve to produce shame, guilt, trust, empathy; social intelligence and conscience are born. Before you know it, Yogi Berra is summing it all up: “Always go to other people’s funerals, otherwise they won’t come to yours.” Language, cognition and morality, Nowak argues, are evolutionary spinoffs of the fundamental need of social creatures to cooperate.