School of economics and management, Dalian University of Technology, Dalian, 116024, China.
Department of Public Administration, Dalian University of Technology, Dalian, 116024, China.
Sci Rep. 2021 Mar 22;11(1):6584. doi: 10.1038/s41598-021-85814-1.
The evolution of costly punishment is a puzzle due to cooperators' second-order free-riding. Previous studies have proposed many solutions mainly focused on reducing the punishment cost or punishing second-order free riders directly or indirectly. We attempt to explain this confusion from the perspective of punishment motivation, which is why the punisher is willing to pay the cost. The answer is that the punisher is egoistic. Egoistic punishment aims to protect punishers' own cooperative benefits shared by the defectors. In such case, egoistic punishers would pay a cost in punishing defectors and retrieve lost payoffs from defectors. Here, we examined the evolution and performance of egoistic punishment and compared it with typical altruistic punishment using classic peer-punishment and pool-punishment modes. Results showed egoistic punishment can evolve and effectively promote cooperation within a large parameter range, whether in a well-mixed or structured population, or through peer-punishment or pool-punishment modes. This result is also robust to different strategy-updating rules. The evolution under the pool-punishment mechanism is more complicated. The influence of parameters is counter-intuitive because of cycle dominance; namely, the cost is the key factor to control the level of cooperation and the fine determines the ratio of the punishers and cooperators. Compared with altruistic punishment, egoistic punishment can promote cooperation in a lower-fine and higher-cost area, especially in the pool punishment mode, and the egoistic punishers have stronger survivability. Egoistic punishers represent the natural fairness in a social system. Results revealed that focusing on individual equity can significantly promote collective cooperation. This study provides another explanation for the evolution of costly punishment.
昂贵惩罚的进化是一个谜，因为合作者存在二阶搭便车行为。先前的研究提出了许多解决方案，主要集中在降低惩罚成本或直接或间接惩罚二阶搭便车者。我们试图从惩罚动机的角度来解释这种困惑，即为什么惩罚者愿意付出代价。答案是惩罚者是自私自利的。自私的惩罚旨在保护惩罚者自己与背叛者共享的合作利益。在这种情况下，自私的惩罚者会在惩罚背叛者时付出代价，并从背叛者那里追回失去的收益。在这里，我们检验了自私惩罚的进化和表现，并将其与典型的利他惩罚进行了比较，使用了经典的同伴惩罚和池惩罚模式。结果表明，自私惩罚可以在很大的参数范围内进化，并有效地促进合作，无论是在均匀混合还是结构化的种群中，还是通过同伴惩罚或池惩罚模式。这一结果在不同的策略更新规则下也是稳健的。池惩罚机制下的进化更为复杂。由于循环优势，参数的影响是反直觉的；即，成本是控制合作水平的关键因素，罚款决定了惩罚者和合作者的比例。与利他惩罚相比，自私惩罚可以在更低罚款和更高成本的区域促进合作，特别是在池惩罚模式下，自私惩罚者具有更强的生存能力。自私的惩罚者代表了社会系统中的自然公平。结果表明，关注个体公平可以显著促进集体合作。本研究为昂贵惩罚的进化提供了另一种解释。
