Watts David P, Muller Martin, Amsler Sylvia J, Mbabazi Godfrey, Mitani John C
Department of Anthropology, Yale University, New Haven, CT 06520, USA.
Am J Primatol. 2006 Feb;68(2):161-80. doi: 10.1002/ajp.20214.
Chimpanzees (Pan troglodytes) have hostile intergroup relations throughout most or all of their geographic range. Hostilities include aggressive encounters between members of neighboring communities during foraging and during patrols in which members of one community search for neighbors near territory boundaries. Attacks on neighbors involve coalitions of adult males, and are sometimes fatal. Targets include members of all age/sex classes, but the risk of lethal intergroup coalitionary aggression is highest for adult males and infants, and lowest for sexually swollen females. The best-supported adaptive explanation for such behavior is that fission-fusion sociality allows opportunities for low-cost attacks that, when successful, enhance the food supply for members of the attackers' community, improve survivorship, and increase female fertility. We add to the database on intergroup coalitionary aggression in chimpanzees by describing three fatal attacks on adult males, plus a fourth attack on an adult male and an attack on a juvenile that were almost certainly fatal. Observers saw four of these attacks and inferred the fifth from forensic and behavioral evidence. The attackers were males in two habituated, unprovisioned communities (Ngogo and Kanyawara) in Kibale National Park, Uganda. We also summarize data on other intercommunity attacks at Ngogo. Our observations are consistent with the "imbalance of power" hypothesis [Manson & Wrangham, Current Anthropology 32:369-390, 1991] and support the argument that lethal coalitionary intergroup aggression by male chimpanzees is part of an evolved behavioral strategy.
黑猩猩（Pan troglodytes）在其大部分或全部地理分布范围内都存在群体间的敌对关系。敌对行为包括相邻社群成员在觅食期间以及巡逻期间的攻击性遭遇，在巡逻时，一个社群的成员会在领地边界附近搜寻邻居。对邻居的攻击涉及成年雄性的联盟，有时是致命的。攻击目标包括所有年龄/性别的个体，但群体间致命联盟攻击的风险对成年雄性和婴儿最高，对处于发情期的雌性最低。对此类行为最有依据的适应性解释是，裂变融合社会结构为低成本攻击提供了机会，一旦成功，就能增加攻击者社群成员的食物供应、提高存活率并增加雌性的繁殖力。我们通过描述对成年雄性的三次致命攻击，以及另外一次对成年雄性的攻击和一次几乎肯定致命的对幼年个体的攻击，来扩充黑猩猩群体间联盟攻击的数据库。观察者目睹了其中四次攻击，并根据法医和行为证据推断出第五次攻击。攻击者是乌干达基巴莱国家公园两个习惯化、未提供食物的社群（恩戈戈和卡尼亚瓦拉）中的雄性。我们还总结了恩戈戈其他社群间攻击的数据。我们的观察结果与“权力不平衡”假说[曼森和兰厄姆，《当代人类学》32:369 - 390，1991]一致，并支持这样的观点，即雄性黑猩猩的致命联盟群体间攻击是一种进化行为策略的一部分。
