University of Turin, Department of Life Sciences and Systems Biology, Via Accademia Albertina 13, 10123, Torino, Italy.
University of Turin, Department of Life Sciences and Systems Biology, Via Accademia Albertina 13, 10123, Torino, Italy; Natural History Museum, University of Pisa, Via Roma 79, 56011, Calci, Pisa, Italy.
Behav Processes. 2021 Mar;184:104338. doi: 10.1016/j.beproc.2021.104338. Epub 2021 Jan 26.
Two of the main hypotheses put forth to explain the function of immature social play are the Social Skill Hypothesis and the Motor Training Hypothesis focussing on whether play can improve social competence to develop cooperative social networks or physical abilities to outcompete others, respectively. Here, we tested these hypotheses on a monkey species, the wild gelada (Theropithecus gelada) from the Kundi plateau, Ethiopia. This species is organized in bands divided in One-Male Units (OMUs), united only via social play. Immatures form 'play units' in which individuals from the same and different OMUs interact. We analysed the potential differences between inter- and intra-OMU play to verify which of the two hypotheses (Social Skill or Motor Training Hypothesis) best explains the function of play in geladas. We analysed 527 video-recorded social play sessions and found mixed support for both hypotheses. In agreement with the Social Skill Hypothesis, we found that play in geladas shows scarce social canalization being similarly distributed across age, sex and group membership. In line with the Motor Training Hypothesis, we detected higher levels of competition (shorter and more unbalanced sessions) in inter-OMU compared to intra-OMU play. Hence, in geladas play can be a tool for both the development of social relationships and the improvement of the physical skills necessary to cope with either future mates or competitors. In conclusion, neither hypothesis can be discarded and both hypotheses concur in explaining why immature geladas peculiarly form 'play units' embracing both ingroup and outgroup members.
有两个主要假说被提出解释未成熟社交玩耍的功能，分别是社交技能假说和运动训练假说，它们分别关注玩耍是否可以提高社交能力以发展合作社交网络或提高身体能力以战胜他人。在这里，我们在埃塞俄比亚昆迪高原的野生狒狒（Theropithecus gelada）物种上测试了这些假说。该物种组织成由一个雄性个体（OMU）组成的群体，仅通过社交玩耍联合在一起。未成年个体形成“玩耍单元”，其中来自相同和不同 OMU 的个体相互作用。我们分析了 OMU 间和 OMU 内玩耍之间的潜在差异，以验证哪一个假说（社交技能或运动训练假说）最能解释狒狒玩耍的功能。我们分析了 527 段视频记录的社交玩耍会议，发现这两个假说都有一定的支持。与社交技能假说一致，我们发现狒狒的玩耍表现出很少的社会定型，在年龄、性别和群体成员身份方面分布相似。与运动训练假说一致，我们发现 OMU 间的玩耍竞争程度更高（会话更短且更不平衡）。因此，在狒狒中，玩耍可以是发展社交关系和提高应对未来配偶或竞争对手所需的身体技能的工具。总之，不能排除任何一个假说，并且两个假说都可以解释为什么未成熟的狒狒特别形成包括同群和外群成员的“玩耍单元”。
