Skin temperature changes in wild chimpanzees upon hearing vocalizations of conspecifics.

Guillaume Dezecache,Christoph D Dahl,Klaus Zuberbühler,Marina Davila-Ross

doi:10.1098/rsos.160816

Abstract

A growing trend of research using infrared thermography (IRT) has shown that changes in skin temperature, associated with activity of the autonomic nervous system, can be reliably detected in human and non-human animals. A contact-free method, IRT provides the opportunity to uncover emotional states in free-ranging animals during social interactions. Here, we measured nose and ear temperatures of wild chimpanzees of Budongo Forest, Uganda, when exposed to naturally occurring vocalizations of conspecifics. We found a significant temperature decrease over the nose after exposure to conspecifics' vocalizations, whereas we found a corresponding increase for ear temperature. Our study suggests that IRT can be used in wild animals to quantify changes in emotional states in response to the diversity of vocalizations, their functional significance and acoustical characteristics. We hope that it will contribute to more research on physiological changes associated with social interactions in wild animals.

Highlights

The question of whether emotional states can be attributed to nonhuman animals has a long history in science [1]
This study examined a physiological correlate of presumed emotional states of wild chimpanzees using infrared thermal imaging, implemented by hearing vocalizations of conspecifics
We tested whether different types of vocalizations and the social contexts they are associated with trigger differential changes in surface body temperature

Summary

Introduction

The question of whether emotional states can be attributed to nonhuman animals has a long history in science [1]. The description of animal behaviour in terms of emotional states has been discouraged on the grounds that such constructs were circular and fictional explanations of animal behaviour with no heuristic value [2,3]. Behaviour in both human and non-human animals is driven by underlying psychological states, including emotions, which are accessible to systematic empirical investigation [4,5,6,7].

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Conclusion