社会合作行为可以给动物的生存和繁衍带来诸多益处。由于动物在抚育后代过程中往往需要大量的投入，在社会群体中，有亲缘关系的成员可以共同承担育幼任务，从而减轻繁殖者的负担或提高其后代的存活率。作为社会合作高度进化的典型代表，灵长类的复杂社会系统为合作抚育行为的发生构建了良好的铺垫。然而，由于相关研究高度依赖于对特定野生种群多方面资料的长期积累，我们对此类系统中的后代抚育策略和合作育幼行为了解有限。本项目基于对秦岭川金丝猴种群长年的研究积累，通过对合作抚育行为的观察、记录和分析，结合微卫星分型技术对后代亲权和个体间亲缘度的鉴定，深入探讨影响雌性个体后代抚养投入和雌性间合作水平的生态和社会因子，并系统检验亲缘选择假说，揭示灵长类复杂社群促进种群繁衍、维持物种延续的系统功能，从而推动高等动物社会合作相关理论的发展和完善。

Social cooperation can enhance the survival and reproductive success of animals. As parental care often requires for large amounts of energy investment, the related group members may share the load of parenting. Such cooperative behavior can lighten the load of the breeders or increase the survival of their offspring. The complex social systems in primates represent the most highly evolved levels of social cooperation. In these systems, we would expect extensive occurrence of female cooperative behavior over infant raising. However, we still have limited knowledge about the patterns and mechanisms of social cooperation over reproduction among these systems, as relevant studies must depend on long-term accumulation of multi-aspects data for specific wild populations. The project aims to examine factors affecting the maternal investment and levels of helping for the caring of infants in golden snub-nosed monkeys, based on long-term demographic data, individual based observational recording and molecular assessment of relatedness between individuals and paternity of the offspring. Based on the results, we can test the kin-selection hypothesis in different ways and probe into the structural function of animal complex social systems to promote the breeding of the population. These findings would lead to a better understanding of the evolution of reproductive strategies and altruistic behaviour among social animals.