Stabilization of tag-mediated interaction by sexual reproduction in an evolutionary agent system

The evolution of cooperation in a system of agents playing the iterated prisoner's dilemma (IPD) is investigated. We present results for the standard two-person IPD as well as the more general N-person IPD (NIPD) game. In our computational model, agents can recognize each other and decide whether to interact or not, based upon ``tags'' (labels). We consider the evolutionary stability of the evolving populations. Previous work is extended by introducing sexual reproduction (recombination) of agents and by analyzing its influence on the evolving populations. We observed the occasional formation of very stable cooperative societies, as opposed to previous results without sexual reproduction. These cooperative societies are able to resist invasions of ``mimics''(defecting agents with the tag of a cooperating agent).