Lutz Meredith C, Ratsimbazafy Jonah, Judge Peter G
Animal Behavior Program, Bucknell University, Lewisburg, USA.
Department of Mathematics, Bucknell University, Lewisburg, USA.
Primates. 2019 May;60(3):247-260. doi: 10.1007/s10329-018-00708-7. Epub 2019 Jan 1.
Although play is seen in many species, its evolutionary function is still largely unknown. Several relevant, proposed hypotheses (such as the training for the unexpected, self-assessment, social skills, and dominance hierarchy hypotheses) make predictions about how animals should optimally choose their play partners based on their familiarity or other demographic variables. We used a social network approach to analyze focal sample data on brown capuchins (Cebus apella), hamadryas baboons (Papio hamadryas), and diademed sifaka (Propithecus diadema) to understand how these species choose their play partners with respect to demographic variables. Using exponential random graph models (ERGMs), we found that sifaka and capuchins generally tended to play with animals who were similar to them. The baboons were only sensitive to age differences in the formation of strong play relationships. Our data most strongly support the training for the unexpected hypothesis, as according to predictions all species preferred to play with animals who were their close social partners, decreasing the possibility of cheating during play. Through the first application (to our knowledge) of ERGMs to primate behavior, we were able to compare the effects of many demographic variables on the complex, interdependent social structure of primates. Applying this tool to additional groups and species will provide further insight into evolutionary mechanisms of play behavior across taxa.
尽管在许多物种中都能观察到玩耍行为，但其进化功能在很大程度上仍然未知。几个相关的、已提出的假说（如对意外情况的训练、自我评估、社交技能和优势等级假说）对动物应如何根据熟悉程度或其他人口统计学变量来最佳地选择玩耍伙伴做出了预测。我们采用社会网络方法来分析褐卷尾猴（僧帽猴属）、阿拉伯狒狒和冕狐猴的焦点样本数据，以了解这些物种在人口统计学变量方面是如何选择玩耍伙伴的。使用指数随机图模型（ERGM），我们发现狐猴和卷尾猴通常倾向于与和它们相似的动物玩耍。狒狒在形成紧密的玩耍关系时只对年龄差异敏感。我们的数据最有力地支持了对意外情况的训练假说，因为根据预测，所有物种都更喜欢与它们亲密的社会伙伴一起玩耍，从而降低了玩耍时作弊的可能性。通过（据我们所知）首次将ERGM应用于灵长类动物行为，我们能够比较许多人口统计学变量对灵长类动物复杂、相互依存的社会结构的影响。将这个工具应用于更多的群体和物种将为跨分类群玩耍行为的进化机制提供进一步的见解。
