Gestural theory of the origins of language

Several lines of evidence suggest that human language originated in manual gestures, not vocal calls. These include: (1) the use of the hands as the more natural way to depict events in space and time; (2) the ability of nonhuman primates to use manual action flexibly and intentionally; (3) the nature of the primate mirror system and its homology with the language circuits in the human brain; (4) the relative success in teaching apes to communicate gesturally rather than vocally; (5) the ready invention of sophisticated signed languages by the deaf; (6) the critical role of pointing in the way young children learn language; and (7) the correlation between handedness and cerebral asymmetry for language. The eventual switch to speech miniaturized the system, selected because it freed the hands for other functions, such as carrying things, and the manufacture and use of tools.