University of Southern California, USC Brain Project
From Mirror Neurons to Complex Imitation in the Evolution of Language and Tool Use
The Mirror System Hypothesis suggests that evolution expanded a basic mirror system for grasping, in concert with other brain regions first to support simple imitation (shared with the common ancestor of humans and great apes) and thence to complex imitation (unique to the hominin line), which includes over-imitation whose apparent drawbacks are in fact essential to human skill transmission. These advances in praxis supported the emergence of pantomime and thence protosign and protospeech. This capacity, it is claimed, was adequate for cultural evolution to then yield language. It is argued that Oldowan tool making corresponds to simple imitation and ape gestural communication, Acheulean tool making corresponds to complex imitation and protolanguage, while the explosion of innovations in tool making and social organization of the last 100,000 years correlate with the emergence of language. Care is taken, however, to distinguish brain mechanisms for praxis from those supporting language.