RT Journal Article SR Electronic T1 Onymity promotes cooperation in social dilemma experiments JF Science Advances JO Sci Adv FD American Association for the Advancement of Science SP e1601444 DO 10.1126/sciadv.1601444 VO 3 IS 3 A1 Wang, Zhen A1 Jusup, Marko A1 Wang, Rui-Wu A1 Shi, Lei A1 Iwasa, Yoh A1 Moreno, Yamir A1 Kurths, Jürgen YR 2017 UL http://advances.sciencemag.org/content/3/3/e1601444.abstract AB One of the most elusive scientific challenges for over 150 years has been to explain why cooperation survives despite being a seemingly inferior strategy from an evolutionary point of view. Over the years, various theoretical scenarios aimed at solving the evolutionary puzzle of cooperation have been proposed, eventually identifying several cooperation-promoting mechanisms: kin selection, direct reciprocity, indirect reciprocity, network reciprocity, and group selection. We report the results of repeated Prisoner’s Dilemma experiments with anonymous and onymous pairwise interactions among individuals. We find that onymity significantly increases the frequency of cooperation and the median payoff per round relative to anonymity. Furthermore, we also show that the correlation between players’ ranks and the usage of strategies (cooperation, defection, or punishment) underwent a fundamental shift, whereby more prosocial actions are rewarded with a better ranking under onymity. Our findings prove that reducing anonymity is a valid promoter of cooperation, leading to higher payoffs for cooperators and thus suppressing an incentive—anonymity—that would ultimately favor defection.