JCJC - Jeunes chercheuses et jeunes chercheurs

De la communication vocale animale au langage humain : approche comparative « cétacé - singe - homme » – ORILANG

Submission summary

Our project takes place in the current debate about the origins of language. It is now internationally recognized that the evolution of vocal communication is a tractable problem if approached in an interdisciplinary way (human/life sciences). Despite their proximity to human, nonhuman primates (NHP) have surprisingly rarely been considered as good models for animal'human comparison. The reason comes from old studies that have suggested that NHP calls were genetically fixed whereas birds, cetaceans and humans presented analogies of acoustic flexibility. This creates an intriguing 'phylogenetic gap' in mammals for theorists dealing with language evolution. Language and animal vocal communication are social acts and we believe that social pressures may have been crucial in their evolution. Moreover, finding precursors of human language in animal vocal communication requires investigating in all the facets of language, i.e. production ' usage ' perception. We propose to challenge or to moderate the suspected 'phylogenetic gap' through a comparative analysis of the social influences on the communication of human infants and mammals more (guenons) or less (dolphins) phylogenetically related to humans. Forest guenons and dolphins are ideal for this study since they rely mostly on calls to communicate given their visually-close habitat. Moreover, studies on forest-dwelling NHP are rare and this might have contributed to underestimate NHP communicative abilities. Recent studies on vocal production, including mine on Campbell's monkeys, are challenging the dichotomy between innately guided NHP calls and acquired human speech. I demonstrated vocal sharing of acoustic signatures between some affiliative partners, regardless of age, relatedness and status. This was the first description of such a phenomenon in NHP while vocal sharing has been well documented in dolphins and humans (notably studied in children by one of our team member). Also, to some extent, vocal plasticity has been described in NHP at the time of unusual social events (disturbance of the group composition). But, the precise social factors structuring the individual repertoires are still largely unknown in dolphins, guenons but also in human infants since most studies concern adults. Three complementary research axes are proposed. Axe 1 will consist in analyzing the social influences on vocal production. We will perform long-term developmental observations in various environmental circumstances to investigate how individual characteristics (sex, age) and/or social characteristics modulate vocal production conducting sometimes to vocal sharing. Children will be observed at school and at home. Dolphins and guenons will be observed in captivity and in the wild, thanks to the collaboration with K. Zuberbühler an internationally-fame specialist of wild guenons leading a field station in Ivory Coast. Moreover, three closely-related NHP forest species, differing in their natural social structures (family, harem, multimale multifemale), will be compared in socially stable contexts and at the time of new social network formations. But focusing the comparison among mammals on abilities other than those associated to production can also show how human and nonhuman primates are alike. Axe 2 will consist in analyzing the social influences on vocal usage and perception. Our previous investigations in guenons have also highlighted the potential existence of primitive forms of language-like properties, i.e. referential communication, proto-syntax and proto-conversation. Field experiments, including guenon call playbacks and predator-simulations, are now needed to confirm that the variability and the communicative rules observed are meaningful to animals. Almost nothing is known in dolphins on that topic so we will extend our investigations at this phylogenetical level. Theoretical discussions will be conducted concerting ethologists, psychologists and linguists to see to which extent these abilities can be seen as precursors of some human language characteristics. The role played by social factors on the acquisition of these abilities in humans will be evaluated by comparing typically and atypically developing children presenting different degrees of social disorders (Williams syndrome, autism). Axe 3 proposes a concrete evolutive biology approach. Forest guenons are interesting because they represent a family of 26 species with a large variety of social systems. We will study the relative weight of phylogeny and social factors (group composition, social network) on the vocal repertoire (size, variability). We expect from this program cross-disciplinary benefits providing important insights for newly emerging theories.

Project coordinator

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

Help of the ANR 0 euros
Beginning and duration of the scientific project: - 0 Months

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