Gestural acquisition: testing the Social Negotiation Hypothesis in detail

• Applicant: Jacques Prieur, Ph.D.
• Subject Area: Developmental and Educational Psychology ; Evolution, Anthropology
• Term: from 2018 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 407023904

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.

• DFG Programme: Research Grants