Leonardo da Vinci was ambidextrous, according to a new study by the Uffizi Gallery.

A study carried out by Florence’s Uffizi Gallery is said to have proved the great Renaissance master Leonardo da Vinci was ambidextrous. These findings, which could upend the long-held belief that Leonardo was left-handed, were announced on Monday, one month prior to the 500th anniversary of Leonardo’s death. The Uffizi studied Leonardo’s earliest-known drawing, dated August 5th, 1473, when the artist was 21 years old. The work is a landscape of Tuscany’s Arno River Valley and Montelupo Castle.

The drawing has words on the front that go from right to left, while further script on the back goes from left to right. Close analysis of the two texts led the researchers to conclude both had been written by Leonardo and showed he had been capable of writing perfectly with both hands.

Art historian Cecilia Frosinini told Reuters:

Leonardo was born left-handed, but was taught to write with his right hand from a very young age. [...] By looking at his writings, including from this drawing, one can see his right-handed calligraphy is educated and well done.

This could potentially mean a great deal for future and past Leonardo attributions, as the left-handed and right-handed mark-making in disputed works was often used as an indicator of Leonardo’s involvement rather than the involvement of an apprentice. In the attribution of the so-called “Nude Mona Lisa” last month, Leonardo’s left-handedness played a key role:

The new analysis [...] found “left-handed charcoal marks pretty much everywhere,” according to Deldicque, suggesting the famously left-handed Leonardo was involved in the drawing’s execution, though other parts of it were likely done by a right-handed apprentice.