There are nearly a hundred or so formalised sign languages in existance. British (BSL) and American (ASL) are the most common used.
BSL and ASL share a few signs, but are generally considered mutually unintelligiable. ASL was the first formalised sign language, and BSL was not formally recognised or taught in Britain until the mid 1970s (the first BSL dictionary wasn't published until 1992). Many other modern sign languages have borrowed extensively from either BSL or ASL.
Some sign languages developed historically as means of communicating between different tribes on sparsely populated continents (Australia, Africa).
Most sign languages for the deaf were initally developed by oral speakers, as direct translations of the spoken words. But Nicaraguan SL is entirely different. The first ever deaf school in Nicaragua was opened in 1981. Attending children who could not speak Spanish and had never been taught any SL before, rapidly developed their own sign language. The closely observed development of this new language has been both fascinating and revealing for linguists.
BSL and ASL share a few signs, but are generally considered mutually unintelligiable. ASL was the first formalised sign language, and BSL was not formally recognised or taught in Britain until the mid 1970s (the first BSL dictionary wasn't published until 1992). Many other modern sign languages have borrowed extensively from either BSL or ASL.
Some sign languages developed historically as means of communicating between different tribes on sparsely populated continents (Australia, Africa).
Most sign languages for the deaf were initally developed by oral speakers, as direct translations of the spoken words. But Nicaraguan SL is entirely different. The first ever deaf school in Nicaragua was opened in 1981. Attending children who could not speak Spanish and had never been taught any SL before, rapidly developed their own sign language. The closely observed development of this new language has been both fascinating and revealing for linguists.