In the 1870s, French-Canadian lumberjacks working in a forest in Northern Maine started exhibiting some very strange symptoms: When they were startled, they would jump, yell, hit things, or even imitate those around them, completely involuntarily. Their disorder was named The Jumping Frenchmen of Maine, and experts still can’t fully explain it.
The condition came to the attention of esteemed neurologist George Miller Beard, who published a description of the lumberjacks’ symptoms in 1878. According to an account of an address Beard gave in 1880, “He found that the disorder began in childhood, was familial, was rarely in females, persisted throughout life, and was characterized by a marked and violent jump in response to sudden noise or startle.”
That startled jump took a bizarre variety of forms. Sometimes, the men would repeat back phrases they heard, a phenomenon called echolalia, or imitate how other people were moving, called echopraxia. They were also likely to follow random commands: “He described a 27-year-old patient who, while filling his pipe with tobacco, was slapped on the shoulder and told to ‘throw it.’ The patient threw the pipe and the tobacco on the grass automatically.” According to the National Association for Rare Disorders (NORD), afflicted people may also involuntarily swear or utter inappropriate phrases, a phenomenon known as coprolalia.
Experts still don’t know what causes the disorder. According to NORD, most believe it’s neuropsychiatric, or caused by a disease of the central nervous system. For a 1986 study, Marie-Helene Saint-Hilaire and Jean-Marc Saint-Hilaire studied eight “jumpers” and reported “In our opinion, this phenomenon is not a neurologic disease, but can be explained in psychological terms as operant conditioned behavior“—that is, behavior that’s reinforced by some response in your environment, like a dog who knows he has to sit before he gets his dinner. In this group of sufferers, it also could have been familial, says Alasdair Wilkins of io9. “This particular instance may have had some genetic component, considering most of the sufferers were closely related and came from one of four families, but that may just speak to the insular nature of the French-Canadian lumberjack community in 19th century Maine.”
But lumberjacks in Maine aren’t the only people who have exhibited these strange symptoms. Similar behavior has been documented in other isolated populations throughout the world, including the “Ragin’ Cajuns” of Louisiana, Malaysians and Indonesians with latah syndrome, and Siberians with the disorder known as myriachit. Despite its persistence, we still don’t know its cause or have an effective treatment. NORD suggests one obvious therapy, however: “Eliminating the practice of intentionally startling and/or teasing an individual so as to cause a jumping response can help to reduce or end episodes.”