Lifetime and fitness: Life process in spatial prisoner's dilemma games

We study the roles of life process in cooperation in spatial prisoner's dilemma games. We assume each individual to have a finite lifetime which is correlated with its current fitness. The correlation is controlled by a free parameter w. Simulation results show that the dynamical changing of individuals' lifetime can promote cooperation. Besides, there exists an optimal region for the parameter In that leads to the highest cooperation level. We understand these results by analyzing the spatial patterns of the system and the distributions of the diversified fitness and lifetime values. Our results may help build more realistic models concerning individuals' life process and illuminate its roles in cooperation. (C) 2011 Elsevier B.V. All rights reserved.