Conflicts between social groups or "intergroup contests" are proposed to play a major role in the evolution of cooperation and social organization in humans and some nonhuman animal societies. In humans, success in warfare and other collective conflicts depends on both fighting group size and the presence and actions of key individuals, such as leaders or talismanic warriors. Understanding the determinants of intergroup contest success in other warlike animals may help to reveal the role of these contests in social evolution. Using 19 y of data on intergroup encounters in a particularly violent social mammal, the banded mongoose (Mungos mungo), we show that two factors, the number of adult males and the age of the oldest male (the "senior" male), have the strongest impacts on the probability of group victory. The advantage conferred by senior males appears to stem from their fighting experience. However, the galvanizing effect of senior males declines as they grow old until, at very advanced ages, senior males become a liability rather than an asset and can be evicted. As in human conflict, strength in numbers and the experience of key individuals combine to determine intergroup contest success in this animal society. We discuss how selection arising from intergroup contests may explain a suite of features of individual life history and social organization, including male eviction, sex-assortative alloparental care, and adult sex ratio.

中文翻译：

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战斗力和经验相结合，决定了在好战的哺乳动物中比赛的成功。

社会群体之间的冲突或“群体间的竞争”被提议在人类和一些非人类动物社会的合作和社会组织的演变中发挥重要作用。在人类中，战争和其他集体冲突的成功取决于战斗群体的规模以及关键人物的存在和行动，例如领导者或护身符战士。了解其他好战动物群体间竞赛成功的决定因素可能有助于揭示这些竞赛在社会进化中的作用。使用 19 年关于一种特别暴力的社会哺乳动物——带状猫鼬 (Mungos mungo) 的群体间遭遇的数据，我们表明两个因素，即成年雄性的数量和最年长雄性（“年长”雄性）的年龄，具有对小组获胜概率的影响最大。老年男性所赋予的优势似乎源于他们的战斗经验。然而，老年男性的激励作用会随着年龄的增长而下降，直到老年男性成为一种负担而不是资产，并且可以被驱逐。与人类冲突一样，人数的力量和关键人物的经验共同决定了这个动物社会中群体间竞赛的成功。我们讨论了来自群体间竞赛的选择如何解释个人生活史和社会组织的一系列特征，包括男性驱逐、性别分类的异父母照料和成人性别比例。年长的男性变成了一种负担而不是一种资产，并且可以被驱逐。与人类冲突一样，人数的力量和关键人物的经验共同决定了这个动物社会中群体间竞赛的成功。我们讨论了来自群体间竞赛的选择如何解释个人生活史和社会组织的一系列特征，包括男性驱逐、性别分类的异父母照料和成人性别比例。年长的男性变成了一种负担而不是一种资产，并且可以被驱逐。与人类冲突一样，人数的力量和关键人物的经验共同决定了这个动物社会中群体间竞赛的成功。我们讨论了来自群体间竞赛的选择如何解释个人生活史和社会组织的一系列特征，包括男性驱逐、性别分类的异父母照料和成人性别比例。