A boy found living wild in the woods became a test case for how humans learn language

In 1800, a boy of about 12 was found living alone in the forests of Aveyron, France, apparently having survived without human contact for years. Physician Jean Itard spent years trying to teach him language, but Victor, as he was named, never learned to speak more than a few words, becoming an early test case for whether there's a critical window for acquiring language.

— Jean Marc Gaspard Itard, The Wild Boy of Aveyron — Reports, 1801 and 1806