From her enigmatic smile to those follow-you-round-the-room eyes, the Mona Lisa's features are arguably the most analysed of any painting in history.
But now scientists say they've discovered previously unseen clues that she was suffering from incurable hair loss.
Examinations of Leonardo da Vinci's 16th-century portrait of Lisa Gherardini, 24, the wife of a Florentine silk merchant, revealed she was in the early stages of alopecia areata – the same condition that robbed TV star Gail Porter of her locks in her thirties.
It can cause rapid and total hair loss when the immune system attacks hair follicles in the scalp.
It affects an estimated 400,000 people in the UK, with women more likely to suffer than men. The peak age for onset is between 25 and 29.
From her enigmatic smile to those follow-you-round-the-room eyes, the Mona Lisa's features are arguably the most analysed of any painting in history
Dr Luigi Laino, of the Institute of Dermatology and Trichology in Rome, concluded that the lack of eyebrows and eyelashes, as well as a receding hairline, was evidence Mona Lisa was in the early stages of the balding condition.
Previous studies of the artwork, which da Vinci completed in 1519, attributed these features to the painting fashion of the time.
Alopecia can be triggered by stress and hormonal changes, and Dr Laino said the portrait subject had endured marriage at 15, losing two children and living with the threat of plague.
Writing in Clinics in Dermatology, he added: 'I propose that the most contemplated face in the history of art be recognised for what, clinically, it has always shown: a young woman with alopecia areata.'