Doctoral Dissertation Research: A test of the vocal grooming hypothesis in the gelada

关于人类语言起源的一个有趣的假设是，它是作为一种“社交工具”出现的，促进了我们与越来越多的人保持关系的能力（“社交修饰假设”）。其基本思想是，社会梳理（促进只有一个人的债券）被取代的声音'梳理'（促进债券与几个人，同时）。事实上，社会纽带对人类和非人类灵长类动物都有适应价值。因此，如果声音接触是维持关系的有效方式，那么选择应该有利于它的发展。尽管有大量的理论支持，然而，社会梳理假说还没有得到实证检验。狮尾狒狒提供了一个很好的模型来测试这一点，因为它们是高度社会化的，特别的声音，并且独特的时间限制，因为它们必须花大部分时间在草地上觅食。这项研究由博士生伊丽莎白约翰逊（密歇根大学），博士的监督下。杰西塔Beehner，将探讨的战略，女性狮尾狒狒采用维持其社交网络，特别强调时发声使用，他们引起的反应，以及是否这样的声音接触补充或取代社会梳理时，时间预算特别紧张。通过利用行为观察，社会网络分析，“压力”激素分析和记录发声的声学分析等方法的组合，这项研究将阐明人类祖先可能保持社会联系的一种可能途径，允许更大的群体和更大的群体凝聚力。这项研究的结果不仅有助于更好地了解雌性狒狒的社会关系，而且还为正在进行的密切相关物种的合作项目提供了比较数据集（例如，anubis和hamadryas狒狒）。此外，这项研究超出了学术界，提高了人们对研究地点（埃塞俄比亚的西米恩山国家公园，世界遗产地处于危险之中）和研究物种的认识，这是埃塞俄比亚高地的特有物种，其保护状态被IUCN红色名录标记为“受威胁”。最后，这个博士论文研究项目通过雇用当地的现场助理（为这些年轻人提供就业机会和继续教育），与公园官员密切合作，并为埃塞俄比亚国民提供教育讲座，为公园的长期生存能力做出了贡献。

One intriguing hypothesis about the origins of human language is that it emerged as a 'social tool,' facilitating our abilities to maintain relationships with an increasing number of people (the "social grooming hypothesis"). The basic idea is that social grooming (which facilitates a bond with only one individual) is replaced by vocal 'grooming' (which facilitates bonds with several individuals, simultaneously). Indeed, social bonds have adaptive value for both humans and non-human primates. Thus, if vocal contact represents an efficient way to maintain relationships, then selection should favor its development. Despite a great deal of theoretical support, however, the social grooming hypothesis has yet to be tested empirically. Geladas provide an excellent model to test this because they are highly social, exceptionally vocal, and uniquely time-constrained because they must spend much of their day foraging on grass. This research by doctoral student Elizabeth Johnson (University of Michigan), under the supervision of Dr. Jacinta Beehner, will explore the strategies that female geladas employ to maintain their social networks, with a specific emphasis on when vocalizations are used, the responses they elicit, and whether such vocal contact supplements or replaces social grooming when time budgets are particularly strained. By utilizing a combination of methods, including behavioral observation, social network analysis, analysis of 'stress' hormones, and acoustic analysis of recorded vocalization, this research will elucidate one possible route by which human ancestors may have maintained social bonds, allowing for larger groups and greater group cohesion. Results from this study not only contribute to a better understanding of female gelada social relationships, but also provide a comparative dataset for on-going collaborative projects on closely related species (e.g., anubis and hamadryas baboons). Further, this research extends beyond academia, raising awareness about the study site (the Simien Mountains National Park of Ethiopia, a World Heritage Site in Danger) and the study species, an endemic species to the highlands of Ethiopia with a conservation status labeled as "Threatened" by the IUCN Red List. Finally, this doctoral dissertation research project contributes to the long-term viability of the park by hiring a local field assistant (providing both employment opportunities as well as continuing education for these young adults), working closely with park officials, and providing educational lectures to Ethiopian nationals.