Think the idea of "Photoshopping" pictures is new? Photo tampering goes back to at least around 1860, though the methods were far more low-tech than today (but surprisingly convincing). Apparently this image of Abraham Lincoln is a mash-up of Lincoln's head and John Calhoun's body. Hany Farid, a Dartmouth University professor of computer science, lays out several examples of photo tampering through the ages and points to tools to detect a cut-and-paste job. We saw it mentioned on the Viz blog on rhetoric, visual culture, and pedagogy.