At Face Value: The Role of Chimpanzee Facial Expressivity in the Evolution of Gestural Communication and Social Bonding
UCLA Department of Anthropology
Primates make frequent use of visual signals when communicating with conspecifics, which includes facial expressions and gestures. These two forms of visual communication are thought to be different from one another: facial expressions are perceived as being spontaneous and inflexible, whereas gestures are perceived as being intentional and flexible. As a result, facial expressions are seldom incorporated in gesture research and theories regarding the evolution of human language. The ability to gesture with the face may be useful for non-human primates who rely extensively on their limbs for locomotion. In this talk, I will present data on whether chimpanzee facial expressions are capable of being used as gestures. In addition, I will also present some preliminary work exploring the relationship between facial mobility and facial expressivity in chimpanzees and gibbons. Primates exhibit high facial variability: they can produce a wide variety of facial muscle movements during bouts of communication. High facial variability is thought to be the result of sociality: being able to produce a greater variety of facial signals may help with the establishment and maintenance of social bonds. However, it is unclear if having greater facial variability results in a greater facial repertoire. In this talk, I will compare facial variability and facial repertoires in two distantly related ape species who differ in their social systems.