Dezecache Guillaume, Crockford Catherine, Zuberbühler Klaus
1Institut Jean Nicod, Département d'études cognitives, ENS, EHESS, CNRS, PSL Research University, Paris, France.
Budongo Conservation Field Station, Masindi, Uganda.
Behav Ecol Sociobiol. 2019;73(8):104. doi: 10.1007/s00265-019-2716-6. Epub 2019 Jul 6.
Animals have evolved a range of communicative behaviours in the presence of danger. Although the mechanisms and functions of some of these behaviours have been relatively well researched, comparatively little is known about their ontogeny, including how animals learn to inform social partners about impending danger. In adult chimpanzees, behaviours in response to dangers involve several channels, particularly alarm calls and simultaneous gaze alternations with nearby recipients. Gaze alternations may allow inexperienced individuals to learn from more experienced ones by assessing their reactions to unfamiliar objects or events, but they may also provide the basis for more advanced social referencing. Here, we were interested in the development of these two common behaviours, alarm calling and gaze alternations, in wild chimpanzees () confronted with a threat. Using a cross-sectional design, we investigated those in 8 infant and 8 juveniles by experimentally exposing them to an unfamiliar but potentially dangerous object, a large, remotely controlled, moving spider model. For alarm calling, we found a positive relation with age, starting at around 28 months, although alarm calls were not consistently emitted until after 80 months. For gaze alternations, we found no age effect, with some of the youngest infants already showing the behaviour. Although its function remains unclear in infant and juvenile chimpanzees, gaze alternations emerge early in chimpanzee development. Alarm calling may require more advanced developmental stages, such as greater perceptual abilities, categorical capacities or more sophisticated social cognition, i.e. an understanding that danger is a collective experience that requires communication.
Alarm calling and other anti-predatory behaviours have been the topic of much research but their ontogenies are still poorly described and understood. Recent studies on the behaviour of wild chimpanzees in threatening contexts have suggested sophisticated social cognitive abilities in adults. How do these behaviours develop in ontogeny? We addressed this question using a field experiment with 8 infants and 8 juveniles exposed to a novel and potentially threatening object in their natural habitat. We found that gaze alternations are present in some of the youngest individuals, potentially revealing early social awareness in chimpanzees. Age did not have an effect on the presence of gaze alternation. We also found that alarm calling was more common in older individuals, suggesting that call production and context of usage must be learnt. We discuss our results in light of developmental theories of social cognition and the role of social learning in the primate lineage.
动物在面临危险时进化出了一系列交流行为。尽管其中一些行为的机制和功能已经得到了相对充分的研究，但对于它们的个体发生过程，包括动物如何学会向社会伙伴通报即将来临的危险，我们所知甚少。在成年黑猩猩中，应对危险的行为涉及多种渠道，特别是警报叫声以及与附近同伴同时进行的目光交替。目光交替可能使缺乏经验的个体通过评估更有经验的个体对不熟悉物体或事件的反应来进行学习，但它们也可能为更高级的社会参照提供基础。在此，我们关注野生黑猩猩在面对威胁时这两种常见行为——警报叫声和目光交替——的发展情况。我们采用横断面设计，通过实验向8只婴儿期和8只少年期的黑猩猩展示一个不熟悉但可能危险的物体——一个大型的、遥控的、会移动的蜘蛛模型，来对它们进行研究。对于警报叫声，我们发现其与年龄呈正相关，大约从28个月开始出现，不过直到80个月后警报叫声才会持续发出。对于目光交替，我们没有发现年龄效应，一些最年幼的婴儿期黑猩猩就已经表现出这种行为。尽管目光交替在婴儿期和少年期黑猩猩中的功能尚不清楚，但它在黑猩猩的发育过程中出现得很早。警报叫声可能需要更高级的发育阶段，比如更强的感知能力、分类能力或更复杂的社会认知，即理解危险是一种需要交流的集体体验。
警报叫声和其他反捕食行为一直是许多研究的主题，但它们的个体发生过程仍描述甚少且理解不足。最近关于野生黑猩猩在威胁情境下行为的研究表明成年黑猩猩具有复杂的社会认知能力。这些行为在个体发育过程中是如何发展的呢？我们通过一项野外实验来解决这个问题，该实验让8只婴儿期和8只少年期的黑猩猩在其自然栖息地接触一个新奇且可能有威胁的物体。我们发现一些最年幼的个体存在目光交替现象，这可能揭示了黑猩猩早期的社会意识。年龄对目光交替的出现没有影响。我们还发现警报叫声在年龄较大的个体中更常见，这表明叫声的发出和使用情境必须通过学习获得。我们根据社会认知的发展理论以及社会学习在灵长类谱系中的作用来讨论我们的结果。
