Evolution of egalitarian punishment
Punishment has been deemed as a key to solve the puzzle of the evolution of cooperation. Recent studies have suggested that altruistic punishment may be motivated by preference for social equality (egalitarian punishment). Here we construct individual-based models to investigate the effectiveness of egalitarian punishment in promoting cooperation. Based on computational experiments, we first show that egalitarian punishment is as effective as classic punishment, which directly observes others' strategies, in a meta-population model. We then use a scale-free network model to show that egalitarian punishment can be effective even when heterogeneity in the number of interactions among individuals is incorporated. Finally, we show that generosity in punishment can affect co-evolution of egalitarian punishment and cooperation.