Agent mobility and the evolution of cooperative communities

INTRODUCTION W e are concerned with whether and how cooperation evolves in social worlds characterized by the presence of selfish agents engaged in repeated relations without central authority. This fundamental problem has been the focus of many studies across all the social sciences as well as philosophy, biology, and computer science. Based on the seminal works of John Maynard Smith [1], and Robert Axelrod [2], the iterated prisoner’s dilemma (IPD) has become the central metaphor for the evolution of cooperation in populations of selfish agents without central authority. To investigate whether and how agents in an IPD can overcome the individual rational choice to defect to achieve the socially optimal outcome of mutual cooperation, we construct an artificial world and then analyze characteristics of that world via simulation. The artificial world that we construct is an anarchic, competitive place populated by agents with limited cognitive and social capabilities whose resources are being constantly drained. Into this harsh environment we introduce agent movement and constrained interactions in the form of spatial neighborhoods, features that we anticipate will foster cooperation. We are interested in several properties of this artificial world. Does it become highly cooperative? If cooperation emerges, is it stable? Do agent movement and the type of movement facilitate the generation of a stable cooperative world? Are there patterns in the kinds of strategies that help generate a cooperative world or in the kinds of strategies that evolve in a cooperative world?