Abstract
Cooperation coexisting with defection is a common phenomenon in nature and human society. Previous studies for promoting cooperation based on kin selection, direct and indirect reciprocity, graph selection and group selection have provided conditions that cooperators outcompete defectors. However, a simple mechanism of the long-term stable coexistence of cooperation and defection is still lacking. To reveal the effect of direct reciprocity on the coexistence of cooperation and defection, we conducted a simple experiment based on the Prisoner’s Dilemma (PD) game, where the basic idea behind our experiment is that all players in a PD game should prefer a cooperator as an opponent. Our experimental and theoretical results show clearly that the strategies allowing opting out against defection are able to maintain this stable coexistence.
Highlights
A great deal of research has been devoted to explain how the evolution of cooperation can be favored by natural selection
For the repeated Prisoner’s Dilemma (PD) game, one of the key assumptions is that the interaction between a pair of individuals will be repeated for several rounds, and no player in the game is able to stop the interaction with his/her opponent[4,11,12,13]
To reveal the fundamental evolutionary force driving the coexistence of C and D, we conduct a simple experiment based on the repeated PD game, where, unlike the classic repeated game, each player can unilaterally break off the pairwise interaction with his/her opponent according to his/her own volition
Summary
A great deal of research has been devoted to explain how the evolution of cooperation can be favored by natural selection. Other studies[11,12] have shown ongoing oscillations between cooperative and defective societies can evolve in theoretical models, possibly explaining such phenomena as the alternate appearance of war and peace[11]. These models still do not provide a simple mechanism to drive the long-term stable coexistence of cooperation and defection. To reveal the fundamental evolutionary force driving the coexistence of C and D, we conduct a simple experiment based on the repeated PD game, where, unlike the classic repeated game, each player can unilaterally break off the pairwise interaction with his/her opponent according to his/her own volition. Different from previous experiments on repeated PD game with outside option[19,20,21,22,23,24,25,26], the expected number of rounds between a pair of individuals is still limited in our experimental design even if these two individuals would like to continue their interaction[4,11,12,13]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
