American Sign Language is a system of communication for deaf people in which meaning is conveyed by hand signals and the position of the hands relative to other body parts (see figure below). For historical reasons, many of its signs are more closely related to French sign language than to British sign language. Chimpanzees, gorillas and orang-utans have been taught to use ASL, with evidence suggesting that they then seem to communicate with it at the level of a 5-year-old human. Some ape language researchers regard such evidence as rather controversial.
