Research presented to a recent symposium at the National Gallery suggests the painting on the right was made by a copyist in Leonardo's studio at precisely the same time Leonardo was painting the original (at left and at top above). Infrared images of the Prado painting were compared with those from the original and conservators found that the underdrawings were similar – providing compelling evidence that the two works were executed at the same time.
The newly discovered work offers a much fresher version of the enigmatic, captivating young sitter, generally acknowledged to be Lisa Gherardini, wife of the Florentine cloth merchant Francesco del Giocondo. "The work has been in restoration for several months... The conservation process has not been finished. We are going to present the finished painting at the Prado in about three weeks.”
For all of you scientists and art/science people out there, consider the ways in which science helps us to construct and improve our art historical knowledge? This recent revision to the literature is just one example.