Most Americans probably have only a vague notion of Rene Descartes, the 17th-century French philosopher and mathematician, as the guy who declared, "Cogito ergo sum" ("I think, therefore I am"). It's ...

A new study casts doubt on the long-held belief that the philosopher's skull was interred with his body, suggesting instead it was subject to the antiquated practice of "skull blasting." What to know: ...