Surbeck Martin, Girard-Buttoz Cédric, Boesch Christophe, Crockford Catherine, Fruth Barbara, Hohmann Gottfried, Langergraber Kevin E, Zuberbühler Klaus, Wittig Roman M, Mundry Roger
Department of Primatology, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig, Germany.
Liverpool John Moores University, Faculty of Science, Natural Sciences and Psychology, Liverpool, UK.
R Soc Open Sci. 2017 May 3;4(5):161081. doi: 10.1098/rsos.161081. eCollection 2017 May.
In several group-living species, individuals' social preferences are thought to be influenced by cooperation. For some societies with fission-fusion dynamics, sex-specific association patterns reflect sex differences in cooperation in within- and between-group contexts. In our study, we investigated this hypothesis further by comparing sex-specific association patterns in two closely related species, chimpanzees and bonobos, which differ in the level of between-group competition and in the degree to which sex and kinship influence dyadic cooperation. Here, we used long-term party composition data collected on five chimpanzee and two bonobo communities and assessed, for each individual of 10 years and older, the sex of its top associate and of all conspecifics with whom it associated more frequently than expected by chance. We found clear species differences in association patterns. While in all chimpanzee communities males and females associated more with same-sex partners, in bonobos males and females tended to associate preferentially with females, but the female association preference for other females is lower than in chimpanzees. Our results also show that, for bonobos (but not for chimpanzees), association patterns were predominantly driven by mother-offspring relationships. These species differences in association patterns reflect the high levels of male-male cooperation in chimpanzees and of mother-son cooperation in bonobos. Finally, female chimpanzees showed intense association with a few other females, and male chimpanzees showed more uniform association across males. In bonobos, the most differentiated associations were from males towards females. Chimpanzee male association patterns mirror fundamental human male social traits and, as in humans, may have evolved as a response to strong between-group competition. The lack of such a pattern in a closely related species with a lower degree of between-group competition further supports this notion.
在一些群居物种中，个体的社会偏好被认为受到合作的影响。对于一些具有裂变融合动态的社会，特定性别的关联模式反映了群体内和群体间合作中存在的性别差异。在我们的研究中，我们通过比较两种亲缘关系密切的物种——黑猩猩和倭黑猩猩的特定性别关联模式，进一步探究了这一假设。这两种物种在群体间竞争水平以及性别和亲属关系对二元合作的影响程度上存在差异。在这里，我们使用了在五个黑猩猩群体和两个倭黑猩猩群体中收集的长期群体组成数据，并针对每只10岁及以上的个体，评估其最常交往的同伴的性别，以及所有与其交往频率高于随机预期的同种个体的性别。我们发现关联模式存在明显的物种差异。在所有黑猩猩群体中，雄性和雌性都更倾向于与同性伙伴交往，而在倭黑猩猩中，雄性和雌性则倾向于优先与雌性交往，但雌性对其他雌性的交往偏好低于黑猩猩。我们的结果还表明，对于倭黑猩猩（而非黑猩猩）来说，关联模式主要由母婴关系驱动。这些关联模式的物种差异反映了黑猩猩中高水平的雄性-雄性合作以及倭黑猩猩中高水平的母婴合作。最后，雌性黑猩猩与少数其他雌性表现出强烈的关联，而雄性黑猩猩在雄性之间的关联更为均匀。在倭黑猩猩中，最具差异的关联是雄性与雌性之间的。黑猩猩雄性的关联模式反映了人类男性的基本社会特征，并且与人类一样，可能是对强烈的群体间竞争的一种进化反应。在一个群体间竞争程度较低的亲缘关系密切的物种中缺乏这种模式，进一步支持了这一观点。
