期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2014
卷号：111
期号：47
页码：16662-16669
DOI：10.1073/pnas.1418639111
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：SignificanceHumans, like chimpanzees, engage in coalitionary violence: Members of both species coordinate lethal activity against conspecifics. The origin and adaptive functions of this behavior are poorly understood, and data from tribal populations are rare. We examine the composition of lethal coalitions from the Yanomamo, a tribal society in Amazonia. In contrast to chimpanzees, Yanomamo coalitions are composed of individuals from different lineages and natal communities. Many coalition partners are ideal marriage exchange partners. Men who kill together more often are more likely to live together in the same village later in life and to engage in marriage exchange. Our results highlight connections between coalitionary aggression and alliance formation and illuminate differences in social structure distinguishing humans from other primates. Some cross-cultural evidence suggests lethal coalitionary aggression in humans is the product of residence and descent rules that promote fraternal interest groups, i.e., power groups of coresident males bonded by kinship. As such, human lethal coalitions are hypothesized to be homologous to chimpanzee (Pan troglodytes) border patrols. However, humans demonstrate a unique metagroup social structure in which strategic alliances allow individuals to form coalitions transcending local community boundaries. We test predictions derived from the fraternal interest group and strategic alliance models using lethal coalition data from a lowland South American population, the Yanomamo. Yanomamo men who kill an enemy acquire a special status, termed unokai. We examine the social characteristics of co-unokais or men who jointly kill others. Analyses indicate co-unokais generally are (i) from the same population but from different villages and patrilines, (ii) close age mates, and (iii) maternal half-first cousins. Furthermore, the incident rate for co-unokai killings increases if men are similar in age, from the same population, and from different natal communities. Co-unokais who have killed more times in the past and who are more genetically related to each other have a higher probability of coresidence in adulthood. Last, a relationship exists between lethal coalition formation and marriage exchange. In this population, internal warfare unites multiple communities, and co-unokais strategically form new residential groups and marriage alliances. These results support the strategic alliance model of coalitionary aggression, demonstrate the complexities of human alliance formation, and illuminate key differences in social structure distinguishing humans from other primates.
关键词：internal warfare ; male coalitions ; fraternal interest groups ; strategic alliances ; Yanomamö
