Cracking da Vinci’s (Genetic) Code

For centuries, determining the authenticity of a purported Vermeer or Pollock has largely relied on circumstantial evidence. Curators debated the fluidity and weight of brushstrokes, analyzed paint ingredients and carbon-dated canvasses, but could never fully erase doubts.  

Now a UMD researcher could change all that—starting with the original Renaissance man’s DNA. 

Cell biology and molecular genetics Assistant Professor Norberto Gonzalez-Juarbe and collaborators in the global Leonardo da Vinci Project (LDVP) announced in January that they have recovered enough human genetic material to link a disputed work by the 15^th-century scientist and artist to letters penned by a Leonardo relative. Their findings were published in the pre-print server bioRxiv and are undergoing peer review. 

Despite Leonardo’s fame and influence, fewer than 25 works are attributed to him, so any new data on possible attribution would be momentous. This type of DNA research has the potential to transform the study of historic art.

“There are so many questions in history that have not been answered,” said Gonzalez-Juarbe, cautioning that the work is still in its early stages. With these “next-gen techniques to study art and cultural artifacts, we can understand history in a biological sense.” 

Gonzalez-Juarbe is a molecular biology expert, skilled at studying systems with low DNA abundance like the lungs. He primarily researches how to better understand immune responses and develop better therapeutics to treat diseases, and was invited to join the LDVP to improve conservation efforts, finding and addressing organisms like bacteria, fungi and parasites that could damage aging artwork. But when members of his team recovered human DNA as well, they realized they had a unique opportunity. 

They connected with the family of a collector who owned the “Holy Child,” a palm-sized red chalk sketch of a baby’s head, believed to be drawn by Leonardo. The child gazes off to the bottom right, with realistic shadows around its forehead, eyes and cheek. 

Gonzalez-Juarbe and colleagues prepped for six months to figure out how they could extract the most DNA without damaging the fragile art. On the day—when they doubled-swabbed lesser-touched areas around the child’s chin and the back of the paper—Gonzalez-Juarbe was the only man allowed to take a sample, with LDVP colleague Rhonda Roby taking additional swabs; the goal was to avoid contaminating the sample with any non-Leonardo Y chromosomes so the team could establish lineage via the male line. 

“It’s incredible to be a part of history,” he said. “If you go to the Louvre, you stand in front of the ‘Mona Lisa,’ but you can’t touch it or do anything with it. Here I am, looking at this drawing raw, with no glass.”

For comparison, they needed Leonardo’s DNA. But the team has yet to be granted access to his tomb, so they turned to material from family members. They settled on a set of letters penned by his father’s cousin in Tuscany. Those missives were a gold mine, with possible skin cells in both the wax sealing his thumbprint and the string tying them together.

The result: DNA from the sketch and the letters shared a Y chromosome profile, strongly suggesting a link. To confirm, they sent blind samples to an unaffiliated lab, which replicated the results. 

Other biological data also suggests the “Holy Child” could be a Leonardo. The team found DNA from oranges; the powerful Medici family, early patrons of his, were the only ones with that citrus in their gardens at the time. They also discovered boar and wolf material, likely from brushes made from animal fur. And there was even malaria, then endemic to Tuscany. “It starts to tell us a story, this environmental DNA,” he says. 

To further establish provenance, the team hopes to test additional Leonardo notebooks and lesser-known pieces—“ones that haven’t been exposed to a lot of retouching over the years”—as well as compare DNA to that of descendants tested by collaborators at the University of Florence.

Following a buzzy piece in Science and other media coverage, requests have flooded in for the team to verify works by other historical giants.

“Now that we have this framework, we can use it for anyone,” said Gonzalez-Juarbe.