Abstract
The Baldwin effect is known as one of interactions between learning and evolution, which suggests that individual lifetime learning can influence the course of evolution without the Lamarckian mechanism. Since Hinton and Nowlan clearly demonstrated this effect by a simple evolutionary simulation, this effect has come to the attention not only of biologists but also of the computer scientists. The purpose of this paper is to clarify the effects of the spatial locality on the evolution of the phenotypic plasticity and the emergence of cooperative behavior in dynamic environments. We adopted a two-dimensional model of the evolution of strategies for Iterated Prisoner's Dilemma (IPD) as a dynamic environment, introduced phenotypic plasticity into strategies, and conducted computational experiments with various settings of two essential factors, one of which concerns the scale of interaction (which decides the neighboring members playing IPD), and another concerns the scale of reproduction (which decides the neighboring candidates occupying each grid in the next generation). In almost all experiments the necessary and sufficient amount of phenotypic plasticity was selected then the population finally established cooperation through the Baldwin effect, but the evolution of the phenotypic plasticity was heavily affected by the settings of these two parameters especially when both of them are small.
