Visual attention, indicative gestures, and calls accompanying gestural communication are associated with sociality in wild chimpanzees (Pan troglodytes schweinfurthii).

Abstract

The challenges of life in complex social groups may select for complex communication to regulate interactions among conspecifics. Whereas the association between social living and vocalizations has been explored in nonhuman primates, great apes also have a rich repertoire of gestures, and how the complexity of gestural communication relates to sociality is still unclear. We used social network analysis to examine the relationship between the duration of time pairs of chimpanzees spent in proximity (within 10 m) and the rates of gestural communication accompanied by visual attention of the signaler, one-to-one calls, indicative gestures (collectively self-relevance cues), and synchronized pant-hoot calls. Pairs of chimpanzees that spent a longer duration of time in proximity had a higher rate of visual gestures accompanied by these behaviors. Further, individual chimpanzees that had a greater number of proximity bonds had a larger social network maintained through gestures accompanied by synchronized pant-hoot calls. In contrast, gestures unaccompanied by these behaviors were not positively associated with either proximity bonds in pairs of chimpanzees or individual differences in sociality. These results suggest that self-relevance cues and synchronized pant-hoot calls accompanying gestures may increase the efficiency of gestural communication in social bonding and that multimodal communication may have played a key role in language evolution. (PsycINFO Database Record (c) 2019 APA, all rights reserved).