Wallace, Tylor, Wundt, Johannesson, and others have proposed that human language had its basis in hand and arm gestures. The Gardners' work with the chimpanzee Washoe, Premack's study of the chimpanzee Sarah, and continuing experiments along these lines indicate that neural restructuring would not have been necessary for the protohominid acquisition of a simple propositional gesture or sign language which did not involve cross-modal transfer at a high level from the visual to the auditory channel or vice versa. Evidence from primate studies, early tool-using, the continuing functions of gesture in human communication, lateral dominance in its relation to speech and tool manipulation, and other sources is presented to support a model of glottogenesis. It is argued that a preexisting gestural language system would have provided an easier pathway to vocal language than a direct outgrowth of the "emotional" use of vocalization characteristic of non-human primates.
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