Recognizing close kin and adjusting one’s behavior accordingly (i.e., favor kin in social interactions, but avoid mating with them) would be an important skill that can increase an animals’ inclusive fitness. Previous studies showed that philopatric female rhesus macaques (Macaca mulatta) bias their social behavior toward maternal and paternal kin. Benefits gained from selecting kin should, however, not only apply to the philopatric sex, for which the enduring spatial proximity facilitates kin discrimination. Given that dispersal is costly, the dispersing sex may benefit from migrating together with their kin or into groups containing kin. In male rhesus macaques, natal migrants bias their spatial proximity toward familiar male kin rather than familiar non-kin. Here, we set up playback experiments to test if males use the acoustic modality to discriminate familiar female kin from non-kin in a non-sexual context. Males responded differently to the presentation of “coo” calls of related and unrelated females, with their reaction depending on the interaction between kin-line (maternal vs paternal kin) and degree of relatedness (r = 0.5, 0.25). Specifically, males were more likely to respond to close kin compared to more distant kin or unrelated females, with this effect being significant in the maternal, but not paternal kin-line. The present study adds to our knowledge of kin recognition abilities of the dispersing sex, suggesting that male rhesus macaques are also able to identify kin using the acoustic modality. We discuss that the probability of response might be affected by the potential benefit of the social partner.

中文翻译：

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雄性恒河猴使用发声来区分雌性母系，但不是父系，亲属与非亲属

识别近亲并相应地调整自己的行为（即在社交互动中偏爱亲属，但避免与他们交配）将是一项重要的技能，可以提高动物的包容性。先前的研究表明，亲缘雌性恒河猴（Macaca mulatta）的社会行为偏向于母系和父系亲属。然而，从选择亲属中获得的好处不仅适用于亲情，持久的空间接近性促进了亲属歧视。鉴于分散成本高昂，分散的性别可能会从与其亲属一起迁移或迁移到包含亲属的群体中受益。在雄性恒河猴中，出生迁徙者的空间接近性偏向于熟悉的雄性亲属，而不是熟悉的非亲属。这里，我们设置了回放实验来测试男性是否使用声学模式在非性环境中区分熟悉的女性亲属和非亲属。男性对相关和不相关女性的“咕咕”声的呈现有不同的反应，他们的反应取决于亲属（母系与父系亲属）和相关程度（r = 0.5, 0.25）之间的相互作用。具体而言，与较远的亲属或无关的女性相比，男性更有可能对近亲做出反应，这种影响在母系中显着，但在父系亲属中不显着。本研究增加了我们对分散性别的亲属识别能力的了解，表明雄性恒河猴也能够使用声学模式识别亲属。