Indeed, gesture processing takes place in areas of the brain such as Broca's and Wernicke'sareas, which are used by speech and sign language (Xu 2009). The faculty of speaking with the hands would not only result from cultural origins, but would also result from a deep neuronal relation connecting the speech to the gestures of the hands (Iverson 1998). There is ample evidence for the ubiquitous link between manual motor and speech systems, in infant development, in deictic pointing, and in repetitive tapping and speaking tasks (Parrel 2014).

Exercise: clapping while speaking

For example, you can break your speech into syllables without even thinking about it, simply by clapping your hands as you speak. You don't need any special training, simply because the motor control of your vocal apparatus is neurologically linked with the motor control of your hands.