Conlangers invent languages for science, pleasure—and the occasional hoax.

The reconstruction of the Taensa grammar was the painstaking work of a French teenager named Jean Parisot. He claimed to have stumbled upon a manuscript in his grandfather's library in the Vosges region of France, and to have realized that it was notes made by unknown explorers who had passed through Taensa territory while the now-extinct people inhabited it.

Parisot's glory was short-lived. The linguists soon became suspicious about his Taensa grammar: The verbs seemed too regular, the relative clause structure too European. And there were anachronisms in the stories and songs he claimed to have transcribed from the manuscript: They contained references to sugar cane, for example, which had only been introduced to Louisiana, by Jesuits, around the time the Taensa disappeared.