Remains from church grave in Florence are compatible with period but cannot be identified as those of Lisa Gherardini

Scientific testing of bone fragments from a church grave in Florence could not determine whether they are from the body of a Renaissance-era woman some believe was the model for Leonardo da Vinci’s Mona Lisa, researchers have said.

Perhaps as enigmatic as her smile, the question of who might have been the model has intrigued art lovers for centuries. Even if bone testing had determined that the remains were those of Lisa Gherardini, the wife of a rich silk merchant, Francesco del Giocondo, it would not have answered the intriguing question of who posed for Leonardo.

Some say he used a male model; others theorise that the artist did a kind of self-portrait in disguise or used several models.

Researchers said carbon-14 testing of one of the fragments indicated that the remains were compatible with the period. Gherardini died aged 63 in 1542, and the researchers said historical documents indicate she was buried in a Florence convent.

The head researcher Silvano Vinceti said there were few remains and no skull, which might have helped to determine whether the woman could have been Leonardo’s model.

Giorgio Gruppioni. head of the forensic anthropology laboratory at the University of Bologna, said: “Our biggest problem has been the fact that the fragments were very fragmented, very deteriorated.” That complicated the task of determining the sex and age at death as well as DNA analysis, he said.

Because no remains have been found of Gherardini’s relatives, any DNA comparison testing was impossible, the researchers said. Still, Vinceti said: “The odds that the bones belong to her are very high.”

Giorgio Vassari, a 16th-century artist and biographer of artists, wrote that Leonardo painted a portrait of Del Giocondo’s wife. The woman has long been linked to the Mona Lisa painting, which is known in Italian as La Gioconda.