Anthropology, University of Wisconsin- Milwaukee
Thursday Afternoon, Grand Ballroom II
Robin Dunbar has argued that language represents the human equivalent of grooming among primates. Both activities act to promote affiliation among individuals, but the fact that language communicates over a distance allows for the maintenance of a larger group size . Both modes of communication serve to increase the benfits of group member. While Dunbar’s argument has attracted much attention, he has not offered a clear evolutionary mechanism by which the neurological effects of physical touch could be taken over by the impact of the spoken word. Here I hypothesize that the shift from reliance on physical touch to auditory communication represents a shift in the importance of sensory inputs within the insula, an area of the brain concerned with the representation of somatic well-being. Parasody or the emotional content of language is known to be processed in the insula. Recent findings among rhesus macaques that species specific vocalizations directly stimulate neuronal firing in the insula suggest an evolutionary precursor for the emotional component of language. At the same time, results among humans demonstrating that physical caress of hairy skin results in activity in the insula suggesting that physical touch may have become restricted to more intimate relationships among humans relative to primates. Together these findings provide support for the decreased important of touch and increased role of vocal communication for group communication in humans. This hypothesis provides a testable scenario by which Dunabar’s gap between grooming and langugue may have been transversed through the course of human evolution.