By Walt Hickey Save To Drafts? A study of the Mona Lisa conducted over 15 years has detected earlier marks in charcoal on the canvas, according to a new paper published in the Journal of Cultural Heritage. Specifically, marks in the hand and hairline show artist Leonardo da Vinci shifted her pose over the course of the painting that made her look more directly at the viewer. The process was accomplished with a multispectral camera that can detect reflected light at over