Sign Language Family Tree: How the World's Sign Languages Are Related

The short answer

Sign languages have their own family trees, and those trees do not follow the spoken languages of the same countries. A sign language's ancestry usually reflects where deaf education and deaf communities spread, not which spoken language surrounds it. American Sign Language (ASL) is historically related to French Sign Language, not to British Sign Language, even though the United States and the United Kingdom share English. One important limit applies: linguists still debate many groupings, and some sign languages fit no known family.

Why sign languages don't copy spoken-language trees

A sign language is a complete natural language with its own grammar and vocabulary. It is not a signed version of a spoken language. Sign languages spread when teachers, schools and deaf communities moved, so their relationships often cross national and spoken-language borders.

Researchers usually rebuild these relationships from three kinds of evidence:

• Historical records of who founded deaf schools and where those founders trained
• Comparisons of shared vocabulary between sign languages
• Shared grammar and other structural features

Each method has limits. Signs that look alike may come from shared ancestry or from borrowing. They can also look alike because both depict the same thing visually, which is common in sign languages. For these reasons, a sign language family tree is a working model, not a settled genealogy.

Commonly described sign language families

The groupings below are widely discussed in general linguistic accounts. The details and boundaries of each are open to scholarly debate.

Family | Commonly cited members | Basis for the grouping

French Sign Language family | French Sign Language, American Sign Language, and several other European and American sign languages | Deaf education models and teachers trained in the French tradition spread to other countries

BANZSL (British, Australian and New Zealand Sign Language) | British Sign Language, Auslan, New Zealand Sign Language | Shared roots carried by British colonial and educational links

Japanese Sign Language family | Japanese Sign Language, Korean Sign Language, Taiwan Sign Language | Historical ties dating from the period of Japanese influence in the region

Isolates and new sign languages | Village sign languages and newly emerged sign languages such as Nicaraguan Sign Language | These arose within local communities and have no clear parent language

The ASL and British Sign Language example

The best-known illustration of this pattern is ASL. ASL formed in the early nineteenth century, when a deaf teacher from the French tradition, Laurent Clerc, helped establish deaf education in the United States. French Sign Language then mixed with sign varieties already used in America, including the sign language of the deaf community on Martha's Vineyard. The result is that ASL and British Sign Language are generally described as mutually unintelligible. ASL users usually find more familiar signs in French Sign Language than in British Sign Language.

Where the family-tree model breaks down

• Contact and mixing: many sign languages formed from several sources blending together. A single-parent tree oversimplifies them.
• Isolates: some community sign languages developed independently and have no known relatives.
• Limited documentation: many sign languages have little historical or comparative research, so their placement is uncertain.
• One country, several languages: a single country can host unrelated sign languages, and one family can span many countries.

What this means for webcam audio

Sign languages are visual. The webcam's microphone does not capture the language itself, whichever family it belongs to. In a video call, the signed content travels through the camera image. A sign language's family has no bearing on microphone choice.

Audio still matters in mixed calls. Examples include a voice interpreter speaking for a signer, or hearing participants speaking to deaf participants through an interpreter or captions. In those cases, clear speech capture helps the interpreter and any automatic captioning. The usual guidance is to pick the correct audio input in the conferencing app and keep the speaker close to the microphone.

Evidence gap: no specific microphone models, specifications or test results were available for this article. It does not recommend particular webcams or microphones for sign language calls.