Gaming theory mathematicians and sociologists have demonstrated how most human behavior, including moralistic aggression, came into existence through evolutionary pressures. Gaming theory was formally developed at Princeton U. by John Von Neumann and Oskar Morgenstern in 1953 (ref. below, see also Wright 1994) and has been used to study a wide variety of activities, particularly evolutionary biology and economics. Perhaps the most famous game theorists was Economics Nobel Laureate, John Nash, who was the primary character in the movie, A Beautiful Mind.

One of the earliest applications was Prisoner’s Dilemma, which was used to demonstrate how altruism came into existence. The premise is two guilty prisoners are captured, but the prosecutor only has the evidence to convict on a lesser crime. So the prisoners are separated and each offered the deal: “If you confess and your partner does not, I will let you off scot-free but your partner will get the maximum sentence. The same deal is being made to your partner. If both of you confess, then you’ll both get a reduced sentence.” (The reduced sentence is still longer than if both defendants just keep quiet.) The dilemma is if the two prisoners could communicate with each other, they could agree to keep quiet, each sharing a small amount of the pain (jail time). In all other circumstances it’s to each prisoner’s advantage to cheat on the other.

In the late 1970s, Robert Axelrod devised a master computer program to study prisoner’s dilemma. He invited experts to develop computer programs to compete against all the others. All programs encountered all the other programs multiple times and each could adjust its strategy. The winner would be the computer program with the least amount of jail time. Anatol Rappaport won with an exceedingly simple 5-line code called TIT FOR TAT, which would simply cooperate on the first encounter and then thereafter would do whatever the other program had done on its previous encounter. All of the other competing computer programs eventually evolved to adapt the TIT FOR TAT strategy.

Our tribal ancestors faced a similar dilemma, having barely enough food to survive. Inevitably, there were times when one or the other families in a tribe would be very close to starvation. An altruistic sharing of food from a neighbor’s highly limited supply was extremely valuable since it could be a matter of life or death. Needless to say, neighbors who engaged in sharing initially and then do so again if only if the other reciprocates sharing among the tribe, were the most successful. Reciprocated altruism (TIT FOR TAT) is so simple, it’s easy to see how evolution hit upon it.

Refs: Robert Wright, 1994 The Moral Animal, Vintage Books, New York, NY.
Von Neumann & Morgenstern 1953, Princeton University Press.