Institute for Quantitative Social Science, Harvard University, Cambridge, Massachusetts 02138, USA.
Nature. 2012 Jan 25;481(7382):497-501. doi: 10.1038/nature10736.
Social networks show striking structural regularities, and both theory and evidence suggest that networks may have facilitated the development of large-scale cooperation in humans. Here, we characterize the social networks of the Hadza, a population of hunter-gatherers in Tanzania. We show that Hadza networks have important properties also seen in modernized social networks, including a skewed degree distribution, degree assortativity, transitivity, reciprocity, geographic decay and homophily. We demonstrate that Hadza camps exhibit high between-group and low within-group variation in public goods game donations. Network ties are also more likely between people who give the same amount, and the similarity in cooperative behaviour extends up to two degrees of separation. Social distance appears to be as important as genetic relatedness and physical proximity in explaining assortativity in cooperation. Our results suggest that certain elements of social network structure may have been present at an early point in human history. Also, early humans may have formed ties with both kin and non-kin, based in part on their tendency to cooperate. Social networks may thus have contributed to the emergence of cooperation.
社交网络显示出显著的结构规律性，理论和证据都表明，网络可能促进了人类大规模合作的发展。在这里，我们描述了坦桑尼亚哈扎人的社交网络，这是一个狩猎采集人群。我们表明，哈扎人的网络具有在现代化社交网络中也能看到的重要特性，包括倾斜的度分布、度关联性、传递性、互惠性、地理衰减和同质性。我们证明，哈扎营地在公共物品游戏捐赠方面表现出高群体间和低群体内的差异。网络关系也更可能存在于给予相同数量的人之间，合作行为的相似性可以延伸到两个分离程度。社会距离在解释合作中的关联性方面似乎与遗传关系和身体接近同样重要。我们的结果表明，在人类历史的早期，某些社交网络结构的要素可能已经存在。此外，早期人类可能与亲属和非亲属都建立了联系，部分原因是他们有合作的倾向。因此，社交网络可能促成了合作的出现。
