Lateralized use of the mouth in production of vocalizations by marmosets

We have found that the common marmoset, Callithrix jacchus, displays a larg er left hemimouth during production of fear expressions, with or without vo calization, and a larger right hemimouth when producing a social contact ca ll. Thus, marmosets have right hemisphere specialization for the production of negative emotional expressions and vocalizations and left hemisphere sp ecialization for the production of social contact communication. These hemi spheric specializations for social communication in marmosets are the same as those found in humans for speech production and for the control of emoti onal expressions. We suggest that hemispheric specializations for communica tion in humans may well have precursors in primate evolution. (C) 1998 Else vier Science Ltd. All rights reserved.