Mysterious!

Humans are equipped at birth with primitive startle reflexes that cause babies to flail uncontrollably in a fight-or-flight fashion. And while most folks outgrow this, a group of 50 French-Canadian lumberjacks — full-grown men — living in the quiet mountains of Moosehead Lake, Maine, and northern New Hampshire in the 19th century exhibited bizarre reactions to being surprised, baffling everyone from neighbors to the world’s most prestigious scientists.