Abstract
If primates were capable of vocalizing to inform a receiver about an external entity, it would represent an important element of continuity with human language. We tested experimentally whether chimpanzee rough grunts, which function to refer to food, are produced selectively, indicating voluntary control, and whether they are directed at specific individuals. These are prerequisites for a system capable of actively informing others about external events. We conducted a field playback experiment in which we presented silently feeding male chimpanzees, Pan troglodytes, with arrival pant hoots of a familiar group member. We found that subjects were significantly more likely to respond with food calls to the simulated arrival of an individual with whom the caller had a high rather than low level of friendship and where there was a large rather than small positive dominance rank difference between the individuals (i.e. caller was lower ranking). We concluded that chimpanzee food calls are not simply reflexive responses to food, but can be selectively directed at socially important individuals. Our findings are thus inconsistent with traditional views of primate vocalizations as inflexibly and indiscriminately produced. Instead, our results indicate that great apes can produce semantically meaningful calls in a highly selective, recipient-directed manner. Further research is needed to test whether chimpanzees use this flexible system to inform ignorant individuals about food, but the prerequisites to support this type of communication seem to be present. (C) 2013 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.
Original language | English |
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Pages (from-to) | 955-965 |
Number of pages | 11 |
Journal | Animal Behaviour |
Volume | 86 |
Issue number | 5 |
DOIs | |
Publication status | Published - Nov 2013 |
Funding
We are grateful to the Budongo Conservation Field Station, which receives core funding from the Royal Zoological Society of Scotland, for supporting this study, the Ugandan Wildlife Authority, the Ugandan Council for Science and Technology and the President's Office for permission to conduct this research in Uganda. Thank you to field assistants Monday Gideon, Jacob Alio, Sam Adue, Jackson Okuti and Robert Eguma without whom we could not have collected the data and to Alejandra Picard for video coding. We are grateful to Cathy Crockford and Roman Wittig for helpful discussions about this study. This research was funded by a BBSRC project grant to K.S., Z.M. was supported by a Wenner-Gren Hunt Fellowship and K.Z. was supported by the Leverhulme Trust.
Keywords
- audience effect
- chimpanzee
- food call
- intentionality
- Pan troglodytes
- rough grunt
- triadic communication
- vocalization
- voluntary control
- FUNCTIONALLY REFERENTIAL SIGNALS
- PAN-TROGLODYTES
- WILD CHIMPANZEES
- ALARM CALLS
- CAPUCHIN MONKEYS
- CEBUS-APELLA
- COMMUNICATION
- LANGUAGE
- IDENTIFICATION
- VOCALIZATIONS