Doebeli Michael, Hauert Christoph, Killingback Timothy
Department of Zoology and Department of Mathematics, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada.
Science. 2004 Oct 29;306(5697):859-62. doi: 10.1126/science.1101456.
Coexistence of cooperators and defectors is common in nature, yet the evolutionary origin of such social diversification is unclear. Many models have been studied on the basis of the assumption that benefits of cooperative acts only accrue to others. Here, we analyze the continuous snowdrift game, in which cooperative investments are costly but yield benefits to others as well as to the cooperator. Adaptive dynamics of investment levels often result in evolutionary diversification from initially uniform populations to a stable state in which cooperators making large investments coexist with defectors who invest very little. Thus, when individuals benefit from their own actions, large asymmetries in cooperative investments can evolve.
合作者与背叛者共存的现象在自然界中很常见，然而这种社会多样性的进化起源尚不清楚。许多模型是在合作行为的益处仅归于他人这一假设的基础上进行研究的。在此，我们分析连续雪堆博弈，其中合作投资成本高昂，但对他人以及合作者自身都能产生益处。投资水平的适应性动态变化往往会导致从最初的同质群体进化出多样性，达到一种稳定状态，即进行大量投资的合作者与几乎不投资的背叛者共存。因此，当个体从自身行为中受益时，合作投资中的巨大不对称性就可能会演化出来。
