Dynamical Modeling of the Demographic Prisoner's Dilemma

Epstein (1998) demonstrates that in the demographic Prisoner's Dilemma game it is possible to sustain cooperation in a repeated game played on a finite grid, where agents are spatially distributed and of fixed strategy type ('cooperate' or 'defect'). We introduce a methodology to formalize the dynamical equations for a population of agents distributed in space and in wealth, which form a system similar to the reaction-diffusion type. We determine conditions for stable zones of sustained cooperation in a one-dimensional version of the model. Defectors are forced out of cooperation zones due to a congestion effect, and accumulate at the boundaries.