Like most mammals, primates possess the special senses of olfaction, taste (gustation), vision and hearing (audition) as well as the general sense of touch (somatosensation). These senses represent the interface between an animal and its environment. Indeed, the survival and fitness of an animal depend upon its ability to accurately and adequately gather sensory stimuli. Olfaction and taste are grouped together as chemical senses because the stimuli they detect are molecules or compounds that either travel through the air or are settled on a physical substrate. Hearing, vision and somatosensation are grouped together as physical senses because the stimuli they detect are physical forces (e.g. sound waves, light, pressure, temperature). While taste is a critical part of an animal’s ability to judge aspects of its environment (such as food quality), it does not play a direct role in social communication and thus will not be included in the ensuing discussion (Dominy, Ross and Smith, 2004).

While we discuss these senses separately from one another for the benefit of conceptualizing their roles in primate communication, we recognize that there is usually a mix of sensory modes that are locked together in any potential interaction. In the following sections, we describe the morphology of each of these sensory systems, how they function to gather and interpret external stimuli and how they are used in primate communication.