Matching Structure and the Evolution of Cooperation in the Prisoner's Dilemma

With the help of both an experiment and analytical techniques, Axelrod and Hamilton [1] showed that cooperation can evolve in a Prisoner's Dilemma game when pairs of individuals interact repeatedly. They also demonstrated that, when pairing of individual is not completely random, cooperating behaviour can evolve in a world initially dominated by defectors. This result leads us to address the following question: Since non-random pairing is a powerful mechanism for the promotion of cooperation in a repeated Prisoner's Dilemma game, can this mechanism also promote the evolution of cooperation in a non-repeated version of the game? Computer simulations are used to study the relation between non-random pairing and the maintenance of cooperative behaviour under evolutionary dynamics. We conclude that non-random pairing can secure cooperation also when the possibility of repeated interaction among the same pairs of individuals is ruled out.