Pandit Sagar A, Pradhan Gauri R, Balashov Hennadii, Van Schaik Carel P
Department of Physics, University of South Florida, 4202 E Fowler Ave, ISA2019, Tampa, FL, 33620, USA.
Anthropological Institute and Museum, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland.
Hum Nat. 2016 Jun;27(2):141-59. doi: 10.1007/s12110-015-9252-5.
Chimpanzees, bonobos, and human foragers share a fission-fusion social system and a mating system of joint male resource defense polygyny. Within-community skew in male strength varies among and within species. In this study, we extend a mathematical model of within-group male coalition formation among primates to derive the conditions for between-community conflicts in the form of raids. We show that the main factor affecting the presence of successful raiding is the likelihood of major discrepancies in party strength, which are set by party size distributions (and thus community size) and the skew in strength. This study confirms the functional similarities between the raiding of chimpanzees and human foragers, and it supports the "imbalance of power" hypothesis for raiding. However, it also proposes two amendments to this model. First, the absence of raiding in bonobos may be attributable more to potential female involvement in defense against raids, which increases the size of defensive coalitions. Second, the model attributes some of the raiding in humans to major contrasts in instantaneous fighting ability created by surprise raids on unarmed victims; it also draws attention to the distinction between minor raids and major raids that involve multiple bands of the same community.
黑猩猩、倭黑猩猩和人类觅食者有着裂变-融合的社会系统以及联合雄性资源防御多偶制的交配系统。群体内部雄性力量的不均衡在不同物种之间以及同一物种内部都存在差异。在本研究中，我们扩展了一个关于灵长类动物群体内部雄性联盟形成的数学模型，以推导以突袭形式出现的群体间冲突的条件。我们表明，影响成功突袭存在的主要因素是群体力量出现重大差异的可能性，这种差异由群体规模分布（进而由群落规模）以及力量不均衡所决定。本研究证实了黑猩猩和人类觅食者突袭行为之间的功能相似性，并支持了关于突袭的“权力失衡”假说。然而，它也对该模型提出了两点修正。第一，倭黑猩猩没有突袭行为可能更多地归因于雌性可能参与抵御突袭，这增加了防御联盟的规模。第二，该模型将人类的一些突袭行为归因于对 unarmed 受害者的突袭所造成的瞬间战斗能力的重大差异；它还提请注意涉及同一群落多个群体的小规模突袭和大规模突袭之间的区别。 （注：原文中“unarmed”一词在翻译时保留英文，因为不清楚其准确含义，可能是特定领域术语，需结合更多背景信息理解）
