Sequential and network analyses to describe multiple signal use in captive mangabeys

Abstract

Although studies on primate communication have mainly focused on single communication systems (gestural, facial or vocal), there is an increasing interest in a more integrative approach to describe the communication of our closest relatives, particularly with the aim of investigating the evolutionary roots of human language. The understanding of the ultimate functions of multimodal (involving signals of different sensory modalities) and multicomponent (association of different signal types) communication needs more systematic description of multiple signal use in primate species, with details on the circumstances leading to such complex signalling. In the present study, we describe the sequential use of communicative signals of different types and sensory modalities in a captive population of catarrhine monkeys, the red-capped mangabey, Cercocebus torquatus . We applied existing analysis methods from other disciplines to define, systematically describe and quantify the production of signals among communicative sequences. We notably used sequence analysis tools (based on dissimilarity measures) to identify the typical signal sequences produced by mangabeys, and network analysis to describe dyadic signal associations among these sequences. The focal observation of five social groups of mangabeys allowed us to identify 424 communicative sequences, which could be grouped into eight main categories, and whose complexity, multimodality and multicomponentiality depended on social context and signaller characteristics. Overall, captive mangabeys frequently associated communication signals of all types (body, facial and vocal signals) and modalities (visual, audible and tactile), in a flexible way. Our results complete previous description of red-capped mangabey signalling and highlight the need for a multimodal and multicomponent approach to understand the complexity of primate communication. Moreover, we propose the method we used as a way to enhance primate communication analysis, in the frame of comparative research. • We describe signal associations among communication sequences in captive mangabeys. • Captive red-capped mangabeys flexibly couple signal types and sensory modalities. • Their communication complexity depends on context and signaller's age and sex. • Play and aggression contexts elicit more complex and multimodal signal sequences. • The method we used may enable comparative research on complex communication events.