Data from: Human cooperation based on punishment reputation

The threat of punishment usually promotes cooperation. However, punishing itself is costly, rare in non-human animals, and humans who punish often finish with low payoffs in economic experiments. The evolution of punishment has therefore been unclear. Recent theoretical developments suggest that punishment has evolved in the context of reputation games. We tested this idea in a simple helping game with observers and with punishment and punishment reputation (experimentally controlling for other possible reputational effects). We show that punishers fully compensate their costs as they receive help more often. The more likely defection is punished within a group, the higher the level of within-group cooperation. These beneficial effects perish if the punishment reputation is removed. We conclude that reputation is key to the evolution of punishment.惩罚的威胁通常能够促进合作。然而，惩罚行为本身需要付出成本，在非人类动物中极为少见，且在经济学实验中，实施惩罚的人类参与者往往只能获得较低的收益。因此，惩罚的演化起源始终未能明晰。近期的理论研究进展表明，惩罚是在声誉博弈的场景下演化形成的。我们通过一项设置了观察者、可实施惩罚以及可建立惩罚声誉的简易互助博弈（同时通过实验控制了其他可能的声誉效应），对这一假说进行了检验。实验结果显示，惩罚者因更频繁地获得他人帮助，完全弥补了自身实施惩罚所付出的成本。群体内对背叛行为的惩罚概率越高，群体内部的合作水平也就越高。但若移除惩罚声誉这一要素，上述有益效应便会荡然无存。我们由此得出结论：声誉是惩罚演化的核心关键。