Social information gathering in lemurs

Abstract

By investigating the cognitive capacities of non-human primates, we can begin to understand the cognitive capacities of the evolutionary ancestors we share with these species. While there is a great deal of research exploring the socio-cognitive abilities of simian primates, prosimians have not been sufficiently studied. Without data from these species, our knowledge about the evolution of the primate mind is limited to the common ancestor shared between simian primates only, precluding understanding of the phylogenetic origins of certain phenomena. I explored the socio-cognitive capacities of lemurs, a type of prosimian primate. I studied several areas of social cognition related to social referencing, defined as the ability to use and seek out social information when appraising objects or events. As social referencing is a popular subject in both human developmental and non-human primate literature, I aimed to determine how prosimians’ capacities compare. My research was conducted with captive lemurs of three species: Eulemur fulvus fulvus, Eulemur macaco macaco, and Eulemur fulvus rufus. I found that lemurs use social cues regarding food palatability to modify their own feeding behaviour and that they visually attend to conspecifics differently when presented with novel, as compared to familiar, foods. Lemurs also visually referred to a human experimenter’s face when presented with an anomalous interaction and went on to engage in gaze alternation. Lemurs failed to use information about the experimenter’s attentional state, however, when modifying their use of a trained gesture. Finally, I found that lemurs are able to visually co-orient with conspecifics, correctly prioritising information from the head over that from the body, and that they go on to use conspecific gaze to locate hidden resources. These results show that lemurs are more cognitively advanced than previously thought and the origins of some social referencing skills may be phylogenetically older than previously hypothesised.