Sign language

Communication by moving parts of the body such as hands, fingers, arms, feet or facial features, or by moving all of the body, and communication by other signals mainly visual but conceivably also tactile, constitute sign language. Thus the deaf call their hand and finger language 'signing'. The hand-signing language of American Indians, and the dance hand-signing language of Hawaiians and Polynesians (hula) are notable examples. Hand-signing is particularly developed in Asia, not only in the dance of Southeast Asia but in Japanese Noh theatre and in Hindu and Buddhist esthetic and yogic theories of mudra. Gestures are not a fully developed sign language but do indicate the extent to which hand signing is instinctive. This is also indicated by the behaviour of other mammalia, from man's 'best friend' who wags his tail to the threatening gestures of crouching felines or rampant apes or bears. Human sign language graphically expresses emotion and is therefore an integral requirement for simulated or theatricized behaviour. It is possible that the full human potentiality to communicate depends on the presence of sign language.