"Your classic prisoner’s dilemma involves two prisoners being interrogated separately. If both deny committing the crime, they serve a short prison sentence. If both confess, they serve a longer prison sentence. But if one confesses, and the other denies, the confessor walks free and the denier does the longest possible sentence. In this scenario, there’s an advantage to cooperating, but a potentially bigger advantage to being selfish, if you’re down to take a risk."
"To test the effectiveness of different strategies, the researchers imagined an evolving population of players, a situation that represents what happens in nature more than repeated head-to-head competition. "Success" in this study just means receiving any abstract payoff a player could find valuable—and the players who receive higher payoffs get to reproduce more, and pass on their wisdom and sage strategies to the next generation. As in the classic prisoner’s dilemma, players could cooperate and create a win-win situation, or defect, and try to secure a bigger advantage for themselves."
"In the long term, extorting, selfish strategies did not work as well as more generous strategies. Players who defected instead of cooperating suffered more over time than players who recognized the value of cooperation--though extortion might provide an advantage in a single head-to-head matchup, in the context of a whole population, over time, it pays to be generous. Sometimes cooperative players would even forgive those who defected and cooperate with them again."
Julie Beck, The Atlantic. Link to article: http://www.theatlantic.com/health/archive/2013/09/study-generosity-is-mo...
Original source: Alexander J. Stewart and Joshua B. Plotkin, Proceedings of the National Academy of Sciences.