Researchers say they're opening up a Florentine family tomb for the first time in centuries as part of their long-running effort to identify the bones of a woman who is thought to be the model for Leonardo da Vinci's Mona Lisa portrait.

DNA testing of bones inside the tomb, in the Martyrs' Crypt behind the main altar of Florence's Basilica della Santissima Annuziata, could confirm that researchers have found the remains of Lisa Gherardini Del Giocondo, a merchant's wife who lived across the street from Leonardo.

The current consensus among art experts is that Lisa Gherardini inspired the artist's 16th-century painting of the woman with the enigmatic smile, which now hangs in the Louvre in Paris.



Linking Lisa to her family

Last year, excavators unearthed several skeletons in the basement of a former Ursuline convent in Florence, where Lisa Gherardini is said to have been buried. But they aren't yet certain which one of the skeletons, if any, is associated with the presumed Mona Lisa model.



"Right now we are carrying out carbon-14 tests on three of the eight skeletons found in St. Ursula, which could be the age Lisa Gherardini was when she died," Silvano Vinceti, who heads Italy's national committee for cultural heritage, told the ANSA news agency. "The carbon-14 test will tell us which of the three dates back to the 1500s. Only then will we know which skeleton to do the final DNA test on."

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That DNA analysis is only half of the job, however. Vinceti and his colleagues also need to confirm the family connection by checking DNA from the remains of Gherardini's two sons. That's why the team plans to take samples from the Gherardini family tomb in the basilica — where the sons and the father, Florentine cloth merchant Francesco Del Giocondo, are buried. ANSA reported that the tomb is to be opened on Friday for the first time in 300 years.

The working scenario for the genesis of the Mona Lisa is that Francesco commissioned the portrait to celebrate Lisa's pregnancy, or the birth of their second child in 1502, or the purchase of a house in 1503. After Francesco's death, Lisa became a nun. She died in 1542 at the age of 63, and was said to be buried near the convent's altar. Such burials were common in those days, which is why the researchers want to make sure they have the right bones.

Reconstructing the face

If the research team verifies a family connection to one of the skeletons from the convent, Vinceti plans to commission a virtual reconstruction of Lisa Gherardini's face, based on the bone structure, and compare it to Leonardo's version.

Scientists have proposed a number of hypotheses for Mona Lisa's smile — ranging from bad teeth to congenital palsy. It’s conceivable that forensic tests on the remains could shed new light on the science behind the smile.

Kristina Killgrove, a bioarchaeologist at the University of West Florida, says Vinceti and his colleagues appear to be "undertaking the excavation professionally" — but she wonders how serious they are about the science, and whether the facial reconstruction will have any basis in reality.



"This will probably bring in some tourist dollars, but other than confirming that this is the Mona Lisa, I don't see any scholarly relevance to it," Killgrove told NBC News. "They could figure out her diet. They could figure out if she had any old injuries or pathological conditions. But I've never seen anything written up about that. And these bones, as far as I can tell from the pictures, are in fairly poor condition."

More about Mona Lisa:

Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the NBC News Science Facebook page, following @b0yle on Twitter and adding +Alan Boyle to your Google+ circles. To keep up with NBCNews.com's stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.