Meeting Minutes - March 6, 2008

During this meeting Ludo presented the paper Evolutionary Games and Spatial Chaos by Martin Nowak and Robert May (Nature, 359, 826-829, 1992). The authors introduce a simple evolutionary model for the emergence of cooperative behavior in prisoner’s dilemmas. Unlike previous models, the model introduced by the authors does not rely on reciprocity to explain cooperative behavior. Instead, the model assumes that agents are located on a two-dimensional grid and interact only with their neighbors. Evolution also takes place locally. It turns out that under these assumptions cooperative behavior can emerge for certain values of the prisoner’s dilemma payoffs. The contribution of the paper is that it provides the important insight that apart from reciprocity the spatial distribution of agents can help to sustain collusion. At the time the paper was published this was a new insight. The results of Nowak and May have been confirmed and generalized in a large number of studies. In addition to biologists, some economists have also been inspired by Nowak and May’s paper and have studied the implications in economic contexts.