Gesture processing takes place in areas of the brain such as Broca's and Wernicke's areas, which are used by speech and sign language.[2] In fact, language is thought to have evolved from manual gestures.[3] The theory that language evolved from manual gestures, termed Gestural Theory, dates back to the work of 18th-century philosopher and priest Abbé de Condillac, and has been revived by contemporary anthropologist Gordon W. Hewes, in 1973, as part of a discussion on the origin of language.[4]