The structural and motivational role of the unique lip‐flip movement in the gelada ( Theropithecus gelada ) facial display repertoire
The structural and motivational role of the unique lip‐flip movement in the gelada ( Theropithecus gelada ) facial display repertoire
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狒狒（Theropithecus gelada）面部展示中独特的翻唇运动的结构和激励作用
DOI：
10.1002/ajpa.24031
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发表时间：
2020
影响因子：
2.8
通讯作者：
Bergman, Thore J.
中科院分区：
文献类型：
--
作者：
Lazow, Stefanie P.;Bergman, Thore J.
人类语言代表了一种极端形式的交际复杂性。灵长类动物的面部显示复杂性依赖于面部活动能力，可以作为研究交流复杂性演化的模型。狒狒（Theropithecus gelada）是唯一一种可以翻动嘴唇的灵长类动物。本研究探讨了相对于露齿行为，唇齿翻转的作用，以了解其在产生交际复杂性中的作用。材料与方法我们回顾了狒狒社会互动的视频。我们使用面部动作编码系统（FACS）来定义每个显示的结构组件动作单元（AUs）。我们从显示发送者的行为中推断出显示动机。结果lip - flip仅与裸露牙齿的基本AUs结合使用，作为可选的结构元件添加以产生结构变体。在没有攻击性和顺从行为的情况下，露齿和不露齿都是最常见的。在噘嘴之前，更频繁的是接近，而不是露出牙齿，尤其是在男性中。在大多数结构混合的面部表情中也出现了翻动，尽管非翻动父母的动机往往占主导地位。唇部翻转可能潜在地起到良性意图的指示作用，或作为非攻击性意图的强化成分。狒狒通过促进翻动嘴唇来增加面部活动的适应性，可能会通过增加显著性和动机信号的规范或强化来提高交流的复杂性。
ObjectivesHuman language represents an extreme form of communicative complexity. Primate facial display complexity, which depends upon facial mobility, can be used as a model for the study of the evolution of communicative complexity. The gelada (Theropithecus gelada) is the only primate that can produce a lip‐flip eversion. This study investigates the role of the lip‐flip relative to the bared‐teeth display to understand its role in generating communicative complexity.Materials and methodsWe reviewed videos of gelada social interactions. We utilized the facial action coding system (FACS) to define structural component action units (AUs) of each display. We inferred display motivation from the behaviors of the display sender.ResultsThe lip‐flip was used only in combination with the essential AUs of the bared‐teeth display, serving as an optional structural element added to produce a structural variant. Both the bared‐teeth display with and without a lip‐flip occurred most frequently with nonaggressive, submissive behaviors. The lip‐flip was more frequently preceded by approach than the bared‐teeth display, especially in males. The lip‐flip was also present in the majority of structurally blended facial displays though the motivation of the non‐lip‐flip parent display often dominated.DiscussionThe lip‐flip may potentially function as an indicator of benign intent after an approach or as an intensifying component of nonaggressive intent. Adaptations to increase facial mobility in geladas via facilitating the lip‐flip may promote increased communicative complexity through increased conspicuousness and motivational signaling specification or intensification.