The Life and Death of Martha's Vineyard Sign Language
From its founding in 1640 through the end of the 1800s, people who were born in Chilmark, a small town on the western end of Martha’s Vineyard, also tended to die in Chilmark.
Two of those people were the children of Jonathan Lambert, a man who had come to Chilmark from Kent, England, in the late 1600s. According to island records, Lambert was deaf; his children, born after his arrival, were the first congenitally deaf residents of Martha’s Vineyard. They were also the beginning of a language and deaf culture unique to the island—one that used to thrive, but is now extinct.
[Don't count on that]
For its first couple centuries, Chilmark was a rural fishing village, isolated from the other towns on the island. Getting to Chilmark from anywhere else “was probably a solid day’s journey over bad roads on a horse,” said Bowdoin Van Riper, the librarian at the Martha’s Vineyard Museum. Other towns had their own ports, which meant a consistent flow of outsiders coming in and out on ships; Chilmark had none. In seclusion, its residents married and had children almost exclusively with one another, and the Lamberts’ hereditary deafness soon spread throughout the town. By the middle of the 19th century, one in every 25 people in Chilmark was deaf. In the U.S. overall, by contrast, that number was roughly one in 5,700.
But Lambert’s legacy was more than genetic. He came to the U.S. speaking what historians presume was a regional sign language from his home in Kent; over the years, it evolved and spread into what would become Martha’s Vineyard Sign Language. And while one in 25 people were deaf, something closer to 25 in 25 knew how to sign. Long before the development of American Sign Language, they used sign as naturally as spoken English, and in every combination: Between deaf people, between deaf and hearing, and even from one hearing person to another. The language didn’t belong to the deaf community; it belonged to the town.
“People tended to think of the deaf folks in Chilmark as individuals first,” Van Riper said, “and not about their disabilities, except in a peripheral way. No different than someone who’s very tall or only has one eye.”
Mainland scientists who heard of Chilmark were puzzled by it, including Alexander Graham Bell, who conducted genealogical research on Martha’s Vineyard in the 1870s in an attempt to isolate the cause of the deafness. “If you look at his research notes … it’s basically page after page of, ‘This person was this person’s grandfather and this was his great-grandfather,” Van Riper said. Mendelian genetics hadn’t yet gone mainstream, “so the actual details of how conditions like deafness were inherited from one generation to another were very poorly understood.”
To the people of Chilmark, though, the remarkably high concentration of deafness wasn’t something that needed to be understood, because it wasn’t remarkable at all. Largely cut off from the rest of the world, they didn’t know the difference.
https://www.theatlantic.com/health/archive/2015/09/marthas-vineyard-sign-language-asl/407191/