Human and Non-Human Primate Preferences for Faces and Facial Attractiveness

Abstract

For humans and non-human primates (NHPs) the face represents a particularly important source of social information providing a means of conspecific recognition and cues to personal details including sex, age, and emotional state. The human face may also be fundamental in the transmission to conspecifics of other forms of socially relevant information including the display of facial traits associated with sexual attraction and mate choice. A wealth of experimental literature indicates that humans display robust preferences for certain facial traits associated with facial attractiveness including preferences for bilateral facial symmetry, facial averageness and sexually dimorphic faces and facial features. It is thought that these preferences have evolved via sexual selection, and may be adaptive, due to the role that these specific facial features play in reliably signalling to others the possession of heritable genetic quality or ‘good genes’. Therefore, from an evolutionary perspective, it is possible that certain facial preferences may represent an evolutionary adaptation for the selection of potential mate quality. However, despite similarities between human and NHP face processing and recognition abilities, the shared evolutionary history and social importance of faces to primates in general, and the potential importance of these preferences in the mate choice decisions of NHPs, very little research has investigated the extent to which NHPs display comparable preferences to humans for these specific facial traits. Consequently, the aim of the following thesis was to comparatively assess the general and more specific preferences that humans and NHPs display for faces and for traits associated with facial attractiveness. Data was compiled from preference studies examining the visual preferences displayed by two species of NHP (brown capuchins (Cebus apella) and chimpanzees (Pan troglodytes)) for conspecific faces manipulated for those facial traits associated with attractiveness, and from a single study of brown capuchins examining their general visual preferences for various types of facial information. Comparative preference studies were also conducted upon human adults and infants examining the visual and declared preferences that they display for manipulations of facial attractiveness.

Data showed that despite possessing general preferences for certain faces and facial information, generally NHPs displayed no significant preferences for those facial traits thought to influences judgements of attractiveness in humans. Possible reasons for this absence of preference for these particular facial traits and the evolutionary implications of these findings are discussed.