The Evolution Of Cooperation In The Prisoner's Dilemma

Darwin's natural selection theory considers "Survival of the fittest", players strive for survival, there are unable to arise cooperation among competitive players. However, the evolution of cooperation becomes a fundamental problem in biology because unselfish, altruistic actions apparently contradict Darwinian selection. Moreover, cooperation is abundant in nature ranging from microbial interactions to human behavior. In particular, cooperation has given rise to major transitions in the history of life. Game theory together with its extensions to an evolutionary context has become an invaluable tool to address the evolution of cooperation. How altruistic behavior emerges in the situations where each individual is apparently tempted to defect has been debated for a long time, In the game theory, this situation is typically formulated as the prisoner's dilemma (PD). To resolve the dilemma and explain the actually found altruism, various mechanisms of cooperation have been proposed, the most prominent are spatial structure, voluntary participation and reciprocal altruism in iterated games.Firstly, the paper presents some essential knowledge, including problems of the evolution of cooperation, the prisoner's dilemma, the iterated prisoner's dilemma and so on. Secondly, it explores the effects of spatial structure and voluntary participation on the evolution of cooperation: In spatially structure systems cooperators may thrive by forming clusters, which reduces exploitation through defectors;Voluntary participation in public enterprises may provide an escape hatch out of some social traps. At last, it analyzes the spatial games of three simple strategies for the iterated prisoner's dilemma: always cooperate (ALLC), always defect (ALLD) and tit-for-tat (TFT), and finds that the spatial games of the iterated prisoner's dilemma leads to a nature selection of reciprocity and enhances the maintenance of cooperation.