Towards a Comparative Approach to Interactional Systems: Cross-disciplinary Contributions from Ethology and Linguistics

Thesis defense of   Lise Habib-Dassetto

Supervisors:

Marie MONTANT, Maîtresse de Conférences – Aix-Marseille Université

Cristel PORTES, Professeure – Aix-Marseille Université

Alban LEMASSON, Professeur – Université de Rennes 1

Les membres du Jury:

Thibaud GRUBER, Rapporteur, Associate Professor – Université de Genève

Elise HUCHARD, Rapporteur(se), Directrice de Recherche – CNRS

Maël LEROUX, Examinateur, Maître de Conférences – Université de Rennes 1

Roxane Bertrand, Présidente du jury, Directrice de Recherche – CNRS

Abstract:

Animal communication research often focuses on the search for meaning and structural rules within signals produced by an emitter, drawing comparisons to human language. Most studies examine only a single communicative modality (vocal, visual, or tactile). This thesis takes a complementary approach by considering communication, in both humans and non-humans, as an interactive social act. It draws on Levinson’s Interaction Engine theory, which posits that humans possess universal predispositions for coordinated interaction, providing evolutionary foundations for language. Human interactions are organized, cooperative, and governed by conventions, such as turn-taking and repair mechanisms. They are also mediated through multimodal communication. To investigate these mechanisms in animals, we adopt principles of ethology, treating communication as a biological trait shaped by evolutionary processes. The thesis is structured along three axes: theoretical, methodological, and empirical. Theoretically, we propose comparing the interactional systems of different species to highlight general properties as well as species-specific patterns. We also advocate integrating all communicative modalities and examining how species’ social and ecological environments shape interactions. Methodologically, we introduce Multi-Interaction, a new framework and open-access tool applicable across species, designed to process multi-agent and multimodal communicative sequences. This method makes it possible to study communicative signals as well as actions produced during exchanges. For the first time, it systematically incorporates intra- and inter-individual overlaps, i.e., the simultaneous production of gestures, vocalizations, facial expressions, and actions, rather than treating these elements sequentially. This approach aims to minimize information loss. It also provides new quantitative measures to describe these sequences. Empirically, we implement these theoretical and methodological approaches in two studies of a captive group of Guinea baboons and in a comparative study across four primate species. Our results show that Guinea baboon interactions are flexible and adapt to social contexts. Individuals contribute in varying proportions depending on their sex and the centrality of their partner. Two interactants also produce inter-individual overlaps in varying proportions according to their sex and the frequency of their exchanges. These results suggest that interactions serve to maintain and negotiate social, hierarchical, and reproductive relationships. We show that, compared to actions, ritualized communicative signals streamline temporal coordination between interactants. Moreover, the size of the interactional repertoire decreases with social experience, indicating that repetition fosters efficiency and conventionalization. Finally, our comparative study of Guinea baboons, chimpanzees, red-capped mangabeys and human infants, highlights different uses of multimodal and multi-component communication, consistent with the social and ecological environments of each species. These results support the Social Complexity Hypothesis (which links the complexity of communication to the constraints of group living) as well as ecological efficacy-based hypotheses (which explains the use of multimodality as an adaptation to ecological constraints). This thesis argues that interactional behaviors across species should be seen as flexible and adaptive biological traits, shaped by conventions as well as by social and ecological pressures.

Keywords: animal communication, social interaction, multimodal communication, evolution, sociality, ecology, primates