Moreover, Meckel has found that deaf-mutism is more frequently met with in flour-mills than elsewhere.
"Anecdotes & Incidents of the Deaf and Dumb"
W. R. Roe
Later, this was followed by mutism, refusal to eat, and stupor.
"Studies in Forensic Psychiatry"
Bernard Glueck
The exceptionally high percentage of deaf-mutism on Martha's Vineyard may to some extent be due to a high percentage of consanguineous marriage, but that inbreeding is not the primary cause is revealed by the records showing that among the first settlers were two deaf-mutes, whose defect has been inherited from generation to generation for two hundred and fifty years.
"Consanguineous Marriages in the American Population"
George B. Louis Arner