The evolution of communication: Humans may be exceptional

Communication is a fundamentally interactive phenomenon. Evolutionary biology recognises this fact in its definition of communication, in which signals are those actions that cause reactions, and where both action and reaction are designed for that reason. Where only one or the other is designed then the behaviours are classed as either cues or coercion. Since mutually dependent behaviours are unlikely to emerge simultaneously, the symmetry inherent in these definitions gives rise to a prediction that communication will only emerge if cues or coercive behaviours do so first. They will then be co-opted for communication. A range of case studies, from animal signalling, evolutionary robotics, comparative psychology, and evolutionary linguistics are used to test this prediction. The first three are found to be supportive. However in the Embodied Communication Game, a recent experimental approach to the emergence of communication between adult humans, communication emerges even when cues or coerced behaviours are not possible. This suggests that humans are exceptional in this regard. It is argued that the reason for this is the degree to which we are able and compelled to read and interpret the behaviour of others in intentional terms.