The function of chimpanzee greeting calls is modulated by their acoustic variation

Signalling plays an important role in mediating social interactions many animal species. For example, during approaches certain species produce ‘greetings’, which can take the form of vocal or visual signals, reduce probability aggressive and/or facilitate affiliation when approaching each other. However, where greetings comprise both and little is known about how component relates to or, with fission–fusion dynamics, time spent together by dyad same subgroup prior approach. Similarly, several acoustic variants greeting calls, it unclear whether different have functions. We looked at production two acoustically distinct call variants, low-fundamental frequency pant grunts high-fundamental barks, between individuals five communities wild chimpanzees, Pan troglodytes, Uganda Ivory Coast. More specifically, we explored relationship (1) submissive approach (2) preceding subsequent proximity levels involved individuals. Calls were more likely be produced associated postures gestures linked submission; these patterns stronger utterance contained a bark rather than grunt alone. The calls was soon after party fusion negatively related caller receiver. These results expand our knowledge imply that might used re-establish dominance relationships period separation, function modulated their specific signals often accompany them.