Social Network Reciprocity as a Phase Transition in Evolutionary Cooperation

摘要

In Evolutionary Dynamics the understanding of cooperative phenomena innatural and social systems has been the subject of intense research duringdecades. We focus attention here on the so-called "Lattice Reciprocity"mechanisms that enhance evolutionary survival of the cooperative phenotype inthe Prisoner's Dilemma game when the population of darwinian replicatorsinteract through a fixed network of social contacts. Exact results on a "DipoleModel" are presented, along with a mean-field analysis as well as results fromextensive numerical Monte Carlo simulations. The theoretical framework used isthat of standard Statistical Mechanics of macroscopic systems, but with noenergy considerations. We illustrate the power of this perspective on socialmodeling, by consistently interpreting the onset of lattice reciprocity as athermodynamical phase transition that, moreover, cannot be captured by a purelymean-field approach.