Do chimpanzees and bonobos communicate differently? First insights from mother-infant interactions — ASN Events

Do chimpanzees and bonobos communicate differently? First insights from mother-infant interactions (#54)

Marlen Fröhlich 1 , Paul H Kuchenbuch 1 , Gottfried Hohmann 2 , Takeshi Furuichi 3 , Roman M Wittig 2 , Simone Pika 1
  1. Humboldt Research Group 'Comparative Gestural Signalling', Max Planck Institute for Ornithology, Seewiesen, Germany
  2. Department of Primatology, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
  3. Primate Research Institute, Kyoto University, Kyoto, Japan

To unravel the evolution of language, the majority of comparative studies have been focusing on our closest living relatives, chimpanzees (Pan troglodytes) and bonobos (Pan paniscus). Interspecific comparisons proposed a distinct bonobo-chimpanzee dichotomy in social behaviour and development, e.g. concerning aspects such as social bonds, sexuality and agonistic interactions. However, recent reports of considerable inter-site variability of chimpanzee behaviour challenge this dichotomy. Since direct comparisons of communicative abilities are still lacking, the present study aimed to examine whether bonobos and chimpanzees use similar or different communicative strategies. To do so, we focused on one communicative function, the initiation of carries for joint travel, and recorded the communicative behaviour of 25 mother-infant dyads in two bonobo (LuiKotal, Wamba; DRC) and two chimpanzee communities (Taï South, Côte d’Ivoire; Kanyawara, Uganda) in the wild (total hours of observation for chimpanzees: 1200; bonobos: 800 hours). We had the following question: Does species affiliation influence the variability and structure of signal production in mother-infant dyads? To answer this question, we focused on actions, gestures and multi-modal signals used to initiate joint travel, as well as 'signal-response' structures (e.g. occurrence of response waiting, gestural sequences and coordinated responses) while taking into account dyadic role and infant age. The analysis of a total of 735 leaving interactions showed that communicative interactions of bonobos and chimpanzees differed in relation to both role and infant age. Specifically, chimpanzees showed a higher frequency of carries that were initiated by gestures, response waiting, sequences and hence, more communicative persistence. In contrast, bonobo carries were more frequently solicited by coordinated responses, i.e. responses to carry-initiating acts were produced while signallers were still in the process of soliciting. Our findings thus add another facet to the Pan dichotomy, which are discussed in relation to hypotheses concerning language origins and sociality.