Sign language

Lore & Background

Groups of deaf people have used sign languages throughout history. One of the earliest written records is from the fifth century BC, in Plato's Cratylus, where Socrates describes making signs with hands, head, and body, 'just as dumb people do at present.' Most pre-19th-century knowledge is limited to manual alphabets invented to transfer spoken words into sign, rather than documentation of the languages themselves. Debate exists over whether European monastic sign languages of the Middle Ages were true sign languages or merely gestural systems.

Reader's Guide

Sign languages are not mime; signs are conventional and often arbitrary, though iconicity is more systematic in sign languages than in spoken ones. Linguists have demonstrated that sign languages exhibit fundamental properties of all languages, including duality of patterning (meaningless units combined into meaningful units) and recursion (grammatical rules whose output can serve as input for the same rule, enabling subordinate clauses). These meaningless units were initially called cheremes but are now often termed phonemes. Sign languages are distinct from body language and from constructed manual codes, home sign, baby sign, and primate signing. International Sign, formerly Gestuno, is used at international deaf events; recent studies consider it more complex than a typical pidgin, closer to a full sign language. Some sign languages have obtained legal recognition.

Did You Know?

• The relative ranking of sign languages by number of users is disputed; Chinese Sign Language, American Sign Language, and Indo-Pakistani Sign Language are among the most widely used, but reliable census data does not con
• Gallaudet University is not the only liberal arts university for deaf people in the world; others include NTID and historically the Korean University of the Deaf.

Nature and Linguistic Status

Sign languages operate through the visual-manual channel rather than sound, combining hand movements with facial expressions, body orientation, and other non-manual markers to carry meaning. They are not simplified versions of spoken language or mere gesture systems; linguists classify them as fully developed natural languages, each possessing its own grammar and vocabulary. Crucially, there is no single universal sign language. Different sign languages are typically not mutually intelligible, even though certain structural similarities can be observed across them. They must be carefully distinguished from body language, which functions as a form of nonverbal communication, and from systems that serve as precursors or derivatives, such as constructed manual codes that map spoken-language words onto handshapes, home sign systems created by isolated individuals, baby sign language programs, and signing systems used with non-human primates. Wherever communities of deaf and hard-of-hearing people have gathered, a sign language has naturally emerged as their primary means of communication and as the foundation of local Deaf culture. While deaf and hard-of-hearing individuals are the primary users, hearing people participate as well, including children of deaf adults who grow up in bilingual households.

Ancient Roots and Early Documentation

The earliest written reference to sign language appears in Plato's Cratylus, dating to the fifth century BC, in which Socrates mused that if humans lacked a voice or tongue, they would naturally attempt to express themselves by moving their hands, head, and body, much as deaf people do. For centuries afterward, most surviving records concern manual alphabets invented to bridge spoken and signed languages, rather than descriptions of the languages themselves. In the Middle Ages, European monastic communities developed gestural systems that modern scholars now regard as proto-sign systems rather than true natural languages; these monastic practices nonetheless provided the foundation for the first manual alphabet used in deaf education, created by Pedro Ponce de León.

The British and French Manual Alphabet Traditions

In Britain, manual alphabets served multiple purposes, from secret communication and public speaking to daily interaction with deaf individuals. The vowels from Dalgarno's system have survived in the modern alphabets used in British Sign Language, Auslan, and New Zealand Sign Language. In France, Charles-Michel de l'Épée published his own manual alphabet in the eighteenth century, which has remained largely unchanged in France and North America to the present day.

Institutional Legacy and Global Reach

Globally, the exact number of sign languages remains uncertain. Each country generally possesses at least one native sign language, and some have several. Some sign languages have achieved varying degrees of legal recognition, and a pidgin-like system called International Sign, formerly known as Gestuno, serves as a lingua franca at major deaf gatherings such as the Deaflympics.