Gestural Communication in Olive Baboons (Papio anubis): Repertoire and Properties.

• Molesti Sandra
• Bourjade Marie
• Meguerditchian Adrien

Given their close phylogenetic proximity with humans, non-human primates are used as model to investigate the evolution of advanced communicative systems. In this regard, studies concerning gestural communication know a renewed interest. In apes, it has been shown that the production of gestures is intentional (e.g. the gestures are adjusted to the attentional state of the recipient), flexible (e.g. the same gesture can be used in several contexts), and variable across individuals and populations. However, compared to apes the gestural communication of monkeys has been understudied. It is thus important to establish which signals are used by monkeys and to investigate whether their gestural system possess the same properties as the gestural system found in apes. In this study we investigated the gestural communication of 47 captive olive baboons of all ages living in three social groups. We used a focal sampling approach to observe each subject for a total of 5 h spread over one year. For each signal produced by the focal subject toward a recipient we recorded its physical description, the orientation of the signaller, the attentional state of the recipient, the situational context and the response of the recipient. We collected a total of 2 820 focal sessions, corresponding to 60 sessions of 5 min for each subject, which allowed to establish a preliminary list of 65 signals produced by the baboons. Preliminary results indicate that 91% of the signals were produced when the signaller was looking at the recipient, and 85% when the recipient was attending. The data will be further analysed to investigate in details the properties of the signals, notably in terms of intentionality, flexibility and variability. This study represents the first systematic investigation of the gestural communicative system of olive baboons and the results will be compared to the gestural system described in apes.