The image: Leonardo Da Vinci's Mona Lisa is probably the world's most famous painting, and one of the most copied. Long before Andy Warhol silkscreened the portrait of Lisa Gerardhini into pop art, dozens of 16th and 17th century artists replicated it. Spain's Prado museum recently discovered that one of these later copies was actually painted at roughly the same time as Da Vinci's original, by a different artist. (See a section, below.) After cleaning old varnish and a layer of black paint from the copy, then using infrared scanning to compare the original drawings under the paint, curators now believe Mona Lisa's "twin sister" was painted alongside Da Vinci's in his studio, probably by his assistant Francisco Melzi. "You can imagine that this is what the Mona Lisa looked like back in the 16th century," says the Prado's Gabriele Finaldi. "It is as if we were... standing at the next easel."

The reaction: Nobody's "yet been bold enough" to ask, but what if "this painting pre-dates Da Vinci's work"? says Jamie Condliffe in Gizmodo. How much would the famous Mona Lisa be worth "if it wasn't the original?" I guess we can add that to the "innumerable conspiracy theories surrounding" Da Vinci's masterpiece, says Mark Brown in Britain's The Guardian. At the least, this cleaned-up version is a clue to what Da Vinci's original once looked like. This is ridiculous, says Jonathan Jones in Britain's The Guardian. Not only is this obviously a copy, it's not a very good one, "more straightforward and less dreamlike" than Da Vinci's. But that's not a surprise: "Leonardo picked his pupils for their looks, not their talent."