Leonardo da Vinci, ahead of his time in so many areas, may have made an attempt to create the world's first example of 3-D art, scientists say.
His most famous work, the portrait of Mona Lisa, might have been part of an attempt on da Vinci's part in the early 1500s to create a stereoscopic 3-D outcome, the researchers have reported.
The portrait that hangs in Paris' Louvre Museum has an almost identical twin in Madrid's Prado Museum, and German researchers say their studies of the two show they were created from slightly altered perspectives.
The perspective of the two portraits is an almost exact match to the slight difference in perspective provided by the separation between a person's left and right eyes, and the two portraits, if combined, would create something very close to a 3-D effect, they say.
"This points to the possibility that the two [paintings] together might represent the first stereoscopic image in world history," the researchers wrote in the journal Perception.
The researchers suggest the two portraits of the Mona Lisa were painted at the same time, with da Vinci doing the most famous one while a student made the copy standing at a position to give a slightly different perspective.
Having a student make another version of a painting was a common practice in Leonardo's studio, the researchers say.
Leonardo might have been purposefully experimenting with putting an impression of depth onto flat canvases, they say.
"It is 'wow,'" says Claus-Christian Carbon of the University of Bamberg. "And this is 330 years before the first stereogram was invented."
When the researchers applied red and cyan tints to digital versions of the two portraits and the combined them, the 3-D effect became apparent when the result was viewed through old-fashioned blue-and-red 3-D glasses like audiences wore to view 3-D movies during their brief fad in the 1950s.
Another mystery of the portrait -- the exact identity of the woman who posed for it -- may also be near a solution, other scientists say.
Long assumed to be a portrait of Lisa Gherardini, the wife of a well-off silk merchant living in 16th century Florence, the proof may come from DNA studies, researchers say.
Silvano Vinceti, director of the National Committee for the Promotion of Historic and Cultural Heritage in Italy, has been searching for her remains for two years.
DNA samples from known remains of her son and husband unearthed in a Florence church are to be compared against remains recovered from a convent nearby, where Lisa Gherardini is believed to have been buried with her daughter, a nun at the convent.
If the DNA matches, forensic anthropologists will attempt to use a computer to generate a 3-D reconstruction of the face of Gherardini to compare with the famous painting.
