Facial expressions are universal？: Development of facial expression research in non-primate species

Abstract

Facial expression research in the past 30 years has been focused mainly on human subjects, while that of other animals, specifically non-primate mammals, has been neglected despite its importance in terms of phylogenetical perspectives. Recently, however, several studies have shown the presence of facial expression in several mammalians such as canids, ungulates, and rodents in a systematic manner. Furthermore, evidence indicate that these species possibly receive facial expressions as communicative signals from conspecifics. This paper reviews research on facial expression in non-primate animals and discusses the significance of understanding the mechanisms and functions of human facial expressions.