Gestural acquisition: testing the Social Negotiation Hypothesis in detail

人类语言的一个独特特征是，它是通过社会中介的互动学习的，在文化上代代相传，在人类社会内部和不同社会之间差异很大。比较进化的方法研究学习在我们最亲近的亲戚的灵活使用和意义中的作用，可以帮助我们理解语言习得的进化机制，从而理解交际文化。手势的起源是一个激烈争论的问题，主要的假设认为系统发育仪式化，个体发生仪式化和/或社会传播是主要的轨迹。然而，最近对生活在两个野生群落中的黑猩猩婴儿的手势发育的研究结果（Fröhlich等人，2016a, b, c, 2017）表明，所提出的假设都不能充分解释自然手势互动中表现出的可变性和灵活性。他们提出了修正后的社会协商假说，该假说认为手势是社会塑造的结果，是互动双方对手势意义的共同理解和实时相互构建的结果。然而，这个假设还没有经过详细的测试，忽略了手势形式的细微差异。此外，生活在稳定的社会群体中的物种呢？拟议的项目将通过研究三组圈养大猩猩（N=35）来解决这些问题，并详细探索修订后的社会谈判假说，研究大猩猩的手势产生（例如手势频率，手和手臂形状的形式，以及表达和理解的动作的大小）在多大程度上受到社会因素（即行为背景，互动成分，学习策略）的影响。我们的研究将集中在两个主要的研究问题上：(1)密切的关系伙伴（即母亲、父亲、兄弟姐妹和不相关的群体成员）在亚成人手势行为的获得和发展中分别扮演什么角色，并关注手势输出和在线生产的细节（特定手势类型中与上下文和相关交互成分相关的手势形式的多样性）？(2)在不同的大猩猩群体中，亚成年大猩猩的手势生产（表达和理解）和相关的社会行为是否存在重叠？如果是，它是否取决于亚成人的社会人口学特征：年龄、性别、亲属关系、隶属关系和等级？为了回答这些问题，我们设计并将采用一种纵向和综合的方法，结合最近研究中取得的成果。这个项目将为灵长类动物的社会化和手势发展提供重要的数据。

One of the unique features of human language is that it is learned through socially mediated interaction, culturally transmitted over generations, and varies substantially within and between human societies. Comparative evolutionary approach investigating the role of learning in the flexible usage and meaning of our closest living relatives’ signalling can help us understand the evolutionary mechanisms underlying the acquisition of language and thereby communicative culture. The origin of gestures is a passionately debated question and the predominant hypotheses suggest phylogenetic ritualization, ontogenetic ritualization, and/or social transmission as main trajectories. However, recent findings on gestural development of chimpanzee infants living in two communities in the wild (Fröhlich et al. 2016a, b, c, 2017), suggested that none of the proposed hypotheses adequately explains the variability and flexibility shown in natural gestural interactions. They proposed the revised Social Negotiation hypothesis, which states that gestures are the ouput of social shaping, shared understanding of gestural meaning and mutual construction in real time by both interactants. However, this hypothesis has not been tested in detail yet, overlooking subtle differences in gestural forms. Furthermore, what about species living in stable social groups? The proposed project will tackle these issues by studying three groups of captive gorillas (N=35) and exploring the revised Social Negotiation hypothesis in detail, studying the extent to which gorillas’ gestural production (e.g. gesture frequency, form of hand and arm shape, and sizes of the expressed and understood repertoires) is shaped by social factors (i.e. behavioural context, interactional component, learning strategy). We will focus our investigation on two main research questions: (1) What respective roles do close bonding partners (i.e. mothers, fathers, siblings and unrelated group members) play in the acquisition and development of subadults’ gestural behaviours with attention paid to the fine details of gestural output and online production (variety of gestural form within a given gesture type in relation to context and associated interactional components)?(2) Is there an overlap of subadults’ gestural production (expressed and understood) and related social behaviours between separate groups of gorillas? If yes, does it depend on the subadults’ sociodemographic characteristics: age, sex, kinship, affiliation and hierarchy? To answer these questions, we designed and will apply a longitudinal and comprehensive approach by combining fruitful methods taken from recent studies. This project will provide crucial data to the important issues in primates’ socialization and gestural development.