From hand actions to speech: evidence and speculations

This chapter reviews experimental evidence and presents new data supporting the idea that human language may have evolved from hand/mouth action representation. Some of the findings include the discovery that the listener's motor system becomes active as if pronouncing the listened words during speech listening and that hand gestures where the hand is not explicitly visible activate the hand-related mirror neuron system, including Broca's region. This chapter concludes that the property of recursion, considered peculiar to human language, may have been introduced to hand actions by the fabrication of tools.