ETH Zurich, CLU E1, Sociology Modeling and Simulation, Zurich, Switzerland.
PLoS One. 2010 Oct 27;5(10):e13471. doi: 10.1371/journal.pone.0013471.
Explaining the emergence and stability of cooperation has been a central challenge in biology, economics and sociology. Unfortunately, the mechanisms known to promote it either require elaborate strategies or hold only under restrictive conditions. Here, we report the emergence, survival, and frequent domination of cooperation in a world characterized by selfishness and a strong temptation to defect, when individuals can accumulate wealth. In particular, we study games with local adaptation such as the prisoner's dilemma, to which we add heterogeneity in payoffs. In our model, agents accumulate wealth and invest some of it in their interactions. The larger the investment, the more can potentially be gained or lost, so that present gains affect future payoffs. We find that cooperation survives for a far wider range of parameters than without wealth accumulation and, even more strikingly, that it often dominates defection. This is in stark contrast to the traditional evolutionary prisoner's dilemma in particular, in which cooperation rarely survives and almost never thrives. With the inequality we introduce, on the contrary, cooperators do better than defectors, even without any strategic behavior or exogenously imposed strategies. These results have important consequences for our understanding of the type of social and economic arrangements that are optimal and efficient.
解释合作的出现和稳定性一直是生物学、经济学和社会学的核心挑战。不幸的是，已知促进合作的机制要么需要精心设计的策略，要么只在限制条件下成立。在这里，我们报告了在一个以自私和强烈的背叛倾向为特征的世界中，合作的出现、生存和频繁主导地位，当个体可以积累财富时。特别是，我们研究了具有局部适应性的博弈，如囚徒困境，并对其收益进行了异质性处理。在我们的模型中，代理人积累财富并将其中一部分投资于他们的互动。投资越大，潜在的收益或损失就越大，因此当前的收益会影响未来的收益。我们发现，合作在比没有财富积累更广泛的参数范围内得以生存，更引人注目的是，合作经常主导背叛。这与传统的进化囚徒困境形成鲜明对比，在传统的进化囚徒困境中，合作很少生存，几乎从未繁荣。相反，与我们引入的不平等相比，合作者的表现优于背叛者，即使没有任何策略行为或外部强加的策略。这些结果对我们理解最优和有效的社会和经济安排类型具有重要意义。
