One of the leading theories for the origin of life includes the hypothesis according to which life would have evolved as cooperative networks of molecules. Explaining cooperation-and particularly, its emergence in favoring the evolution of life-bearing molecules-is thus a key element in describing the transition from nonlife to life. Using agent-based modeling of the iterated prisoner's dilemma, we investigate the emergence of cooperative behavior in a stochastic and spatially extended setting and characterize the effects of inheritance and variability. We demonstrate that there is a mutation threshold above which cooperation is-counterintuitively-selected, which drives a dramatic and robust cooperative takeover of the whole system sustained consistently up to the error catastrophe, in a manner reminiscent of typical phase transition phenomena in statistical physics. Moreover, our results also imply that one of the simplest conditional cooperative strategies, "Tit-for-Tat", plays a key role in the emergence of cooperative behavior required for the origin of life.
Keywords: cooperation; critical phenomena; origin of life; prisoner’s dilemma; stochasticity; thresholds.