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Audience awareness in primates
Responsable du projet Klaus Zuberbühler
   
Collaborateur Pawel Fedurek
Yaëlle Bouquet
   
Résumé One way by which humans communicate is to inform ignorant recipients of relevant external events. This is particularly evident in human language, a highly cooperative, partially learned social behaviour that is based on sharing intentions and enables joint activities (Tomasello 2008). Although animals can produce distinct signals to external events, their communication behaviour is usually interpreted as evolved, inbuilt behavioural mechanisms, which are not targeted at specific recipients or determined by them. Animal and human communication, in this view, are of a fundamentally different nature. How, when and why did human-like audience awareness emerge in the primate lineage? At the proximate level, human communication is based on the cognitive capacity to perceive others as independent agents with personal beliefs and intentions, the human theory of mind. It also requires a motivation to use communication signals to reduce differences between one’s own and others’ mental states. Without these ingredients, communication remains restricted to regulating basic social and biological functions, with little awareness of others. This research project seeks to explore the evolutionary origins of audience-aware communication, as present in humans, by investigating how non-human primates take others into account during acts of communication.

The comparative approach has been a particularly successful research tools when investigating the evolutionary origins of behaviour and cognition. For human traits, the ideal research programme encompasses studies with a large number of primate species from all major groups but, for obvious reasons, this is not always practical. Instead, a few species have been selected to shed light on two crucial intersections in primate evolution, the split between Old World monkeys and apes, roughly 25 million years ago, and the split between apes and humans, about 6 million years ago. A long-standing hypothesis in primatology has been that great apes are cognitively more advanced, and more similar to humans, than monkeys. There is some evidence that chimpanzees show some audience awareness during communication, but the nature of this awareness is not well described and there are no comparable studies on monkeys (see below). The goal of this project is to investigate these problems, by comparing three different monkey species with chimpanzees.

Research will be with chimpanzees (Pan troglodytes), sooty mangabeys (Cercocebus atys), olive baboons (Papio anubis), and vervet monkeys (Chlorocebus aethiops). Chimpanzees, most closely related to humans, will provide insights into the communication abilities of the most recent common ancestor. Baboons, mangabeys, and vervet monkeys, more distantly related, will help to understand the older phylogenetic roots of advanced communication. The three monkey species have been selected because they resemble chimpanzees in basic social organisation but also show important socio-ecological differences. All species form multi-male, multi-female groups, and all are mainly terrestrial, but they differ in average group size. This is important because, in primates, group size is related to relative brain size, the most likely source of cognitive differences (Dunbar 1996). Chimpanzees and sooty mangabeys live in large groups of 50-100 individuals. Olive baboons and vervet monkeys form smaller groups of around 20-40 individuals. Another difference is that chimpanzees practise fusion-fission grouping, which has also been observed in sooty mangabeys (Range & Noë 2002), but not in the other two species. Fusion-fission grouping restricts how much individuals are able to directly and continuously monitor each other, which is likely to favour the ability to mentally represent others and their social relations. Finally, there are differences in terms of preferred habitat, which will impact on how much visible access individuals have to each other. Sooty mangabeys and chimpanzees generally prefer dense forest habitats, while baboons and vervet monkeys prefer more open woodland habitats. Judging from these differences, chimpanzees and sooty mangabeys are likely to experience more variation in audience composition, with a larger number of individuals and in visually more difficult habitat, than baboons and vervet monkeys. One prediction might be that natural selection will have favoured advanced communication especially in the first two species.

A series of field experiments will be carried out to explore a key feature of human communication, the ability to take others into account during communication. We will expose members of the different species to various natural situations that necessitate communication: maintaining relationships, resolving social conflict, discovering food, and dealing with predators. Each species’ communication behaviour will first be studied systematically, using standard behavioural observation protocols. Once the basic patterns are described, systematic field experiments will be carried out. In brief, a first manipulation is to artificially simulate the call-eliciting event, for example by positioning food or a predator model. A second manipulation then is to artificially alter the audience composition, by simulating the arrival of different types of group members. These experiments will provide systematic comparative information on how each species responds to similar events and how signallers allocate their communication efforts in the presence of others.
   
Mots-clés communication, primates, audience, chimpanzees, mangebeys, baboons, vervet monkeys
   
Type de projet Recherche fondamentale
Domaine de recherche cognition comparée
Source de financement FNS - Encouragement de projets (Div. I-III)
Etat Terminé
Début de projet 1-4-2013
Fin du projet 31-3-2016
Budget alloué 606'382.00
Contact Andrea Bshary