Martha's Vineyard Sign Language

Martha's Vineyard Sign Language (MVSL) is a sign language (now extinct), once widely used on the island of Martha's Vineyard off the coast of Massachusetts, U.S., from the early 18th century to the mid 20th century. It was remarkable for its use by both deaf and hearing people in the community; consequently, deafness did not become a barrier to participation in public life. Martha's Vineyard Sign Language is also notable for the role it played in the development of American Sign Language.

The language was able to thrive on Martha's Vineyard because of the unusually high percentage of deaf islanders. In 1854, when the island's deaf population peaked, the United States national average was one deaf person in 5728, while on Martha's Vineyard it was one in 155. In the town of Chilmark, where most of the deaf people lived, it was 1 in 25; in a section of Chilmark called Squibnocket, as much as a quarter of the population of 60 was deaf.

Hearing people sometimes signed even when there were no deaf people present: children signed behind a schoolteacher's back; adults signed to one another during church sermons; and farmers signed to their children across a wide field, where the spoken word would not carry. Frequently, the punchlines to dirty jokes were told only in sign language.

Origins
The ancestry of most of the deaf population of Martha's Vineyard can be traced back to a forested area in the south of England known as the Weald — specifically the part of the Weald in the county of Kent. Martha's Vineyard Sign Language may be a descendant of from a hypothesized sign language of that area in the 16th century, now referred to as Old Kent Sign Language. A number of families from a puritan community in the Kentish Weald emigrated to the Massachusetts Bay Colony area of the United States in the early 17th century, many of their descendants later settling on Martha's Vineyard. The first deaf person known to have settled there was a carpenter and farmer Jonathan Lambert, who moved there with his hearing wife in 1694. By 1710, the migration had virtually ceased, and the endogamous community that was created contained a high incidence of hereditary deafness that would persist for over 200 years.

However it arose, by the 18th century there was a distinct Chilmark Sign Language, which was later (19th century) influenced by French Sign Language, forming Martha's Vineyard Sign Language (19th & 20th centuries). From the late 18th to the early twentieth century, virtually everyone on Martha's Vineyard possessed some degree of fluency in the local sign language.

Deaf migration to the mainland
In the early 19th century, a new educational philosophy began to emerge on the mainland, and the country's first school for the deaf opened in 1817 in Hartford, Connecticut (now called the American School for the Deaf). Many of the deaf children of Martha's Vineyard enrolled there, bringing their sign language with them. However, the language of the teachers was French Sign Language, and many of the other deaf students used their own home sign systems. This school became known as the birthplace of the Deaf community in the U.S., and the different sign systems used there, including MVSL, merged to become American Sign Language or ASL — now one of the largest community languages in the country.

As more deaf people remained on the mainland, and others who returned brought with them deaf spouses they met there, the line of hereditary deafness began to diminish. As the 20th century came to a turn, the previously isolated community of fishers and farmers began to see the influx of tourists that would become a mainstay in the island economy. The jobs in tourism were not as deaf-friendly as fishing and farming had been. Further, as intermarriage and migration joined the people of Martha's Vineyard to the mainland, the island community more and more resembled the wider community there.

The last deaf person born into the island's sign language tradition, Katie West, died in 1952. However, a few elderly residents were able to recall MVSL as recently as the 1980s when research into the language began.