Decoding Mona Lisa’s mysterious smile

A new book suggests that her dark, scandalous life may hold the secret

Mona Lisa – the enigmatic muse of Italian polymath Leonardo da Vinci's famous painting – was married off to a much older slave trader at the age of 15, according to a new book which suggests that her dark life may hold the secret to her mysterious smile.

In the book Mona Lisa: The People and The Painting, authors Martin Kemp from the UK and Giusepps Pallanti from Italy reveal the events of the dark life of Lisa Gherardini – the painting's reallife Mona Lisa – and others involved in the work. Gherardini, born in Florence in June 1479, was married at the age of 15 years to a much older Francesco del Giocondo, who was a wealthy 30year-old merchant and widower in 1495.

A prominent Florentine businessman, del Giocondo kept slave girls to serve as maids throughout his life and for generations before, 'New York Post' reported. "Since his childhood Francesco had lived side by side with some female slaves who had converted to Christianity, bought by his father, and after (his father's) death it was his responsibility to find new ones. Sometimes he bought more slaves than he needed," the authors wrote.

He regularly bought girls from North Africa and converted them to Christianity with many working as maids at the del Giocondo household and it seems likely, and that "he took part in the slave trade." The authors list the names of young girls he had baptised, noting that there were simply too many to have served in the del Giocondo household. "They could not have all remained in his household. Three were too many and one or all of them would have been sold on," they write.

It is unclear how da Vinci came into contact with Gherardini, but it is known that the artist's father was a lawyer and her husband was one of his clients. In 1503, the master painter started working on a portrait of the woman who would be his most famous subject in the years to follow.