Evolution of Compassion Under Un-Repeated Interaction

Abstract

Altruistic behaviors from the haves to the have-nots are often observed in human societies and ecosystems (e.g. assistance among dolphins, and food sharing among vampire bats and among human beings). In this paper, we investigate how the altruistic behaviors, which we call “compassion”, evolve in the situation where pairs of individuals do not repeatedly interact. The results of the computer simulation show the following two results: (1) There exist three types of evolutionary dynamics: (i) the dominance of unconditional non-helpers who never help others; (ii) the coexistence of compassionate individuals who help others who are worse off than themselves and unconditional helpers who always help others; and (iii) the cyclical dominance of unconditional helpers and unconditional non-helpers. (2) Under some parameter settings, cooperative societies where about 60~70% of actions are altruistic are stably realized.