Rhesus monkeys correctly read the goal-relevant gestures of a human agent

Abstract

When humans point, they reveal to others their underlying intent to communicate about some distant goal. A controversy has recently emerged based on a broad set of comparative and phylogenetically relevant data. In particular, whereas chimpanzees ( Pan troglodytes ) have difficulty in using human-generated communicative gestures and actions such as pointing and placing symbolic markers to find hidden rewards, domesticated dogs ( Canis familiaris ) and silver foxes ( Urocyon cinereoargenteus ) readily use such gestures and markers. These comparative data have led to the hypothesis that the capacity to infer communicative intent in dogs and foxes has evolved as a result of human domestication. Though this hypothesis has met with challenges, due in part to studies of non-domesticated, non-primate animals, there remains the fundamental question of why our closest living relatives, the chimpanzees, together with other non-human primates, generally fail to make inferences about a target goal of an agent's communicative intent. Here, we add an important wrinkle to this phylogenetic pattern by showing that free-ranging rhesus monkeys ( Macaca mulatta ) draw correct inferences about the goals of a human agent, using a suite of communicative gestures to locate previously concealed food. Though domestication and human enculturation may play a significant role in tuning up the capacity to infer intentions from communicative gestures, these factors are not necessary.