The Mona Lisa's smile is now a little less enigmatic. A German academic claims that he has definitive proof as to the identity of the model for da Vinci's famous painting, who he believes is Lisa Gherardini, the wife of a wealthy Florentine merchant. The researcher found notes in the margins of a book, dated 1503, detailing Gheradini as the portrait-sitter. In response to this, we smile, albeit coyly. [UPI]