Searching for and perhaps finding Leonardo da Vinci's DNA

A research group reports a potential breakthrough in the search for the genetic material of the Renaissance scientist and artist Leonardo da Vinci: they have found male DNA on a chalk drawing attributed to da Vinci (not pictured). There is no certainty, but the methods used are already a milestone.

On Tuesday, a research group published their methods and findings. The report, which has not yet been independently peer-reviewed, is titled “Biological signatures of history: Examination of composite biomes and Y chromosome analysis from da Vinci-associated cultural artifacts.” According to the report, they extracted DNA samples from the chalk drawing, known as “Holy Child” and depicting the head of a toddler, using forensic methods. They had practiced this on less valuable artworks.

On the “Holy Child,” the researchers found DNA from bacteria, plants, fungi, viruses, and also a man, particularly on the reverse side. The image is believed to have been created around 1474, which is quite some time ago. Meanwhile, several men have likely handled the artwork, which is why the finding cannot be immediately attributed to the draftsman. This is also the reason more prominent works by da Vinci are not the focus: they have passed through many more male hands and have been repeatedly cleaned.

Here we go

However, the male DNA found is not the end of the story, but perhaps its beginning. Initially, the man who acquired the painting about 25 years ago could be ruled out as the source.

However, there are letters and other documents from da Vinci's relatives. These have also been influenced over the centuries, of course. In a wax seal applied with a thumbprint, the researchers found many male chromosomes. The comparison of approximately 90,000 base pairs revealed that both samples, the one from the chalk drawing and the one from the relative, originate from the same haplogroup E1b1b, which is common in Tuscany.

The non-human DNA is also helpful in the trace search: it provides a profile of the plants, bacteria, fungi, and viruses present in the environment, from orange trees to pathogens. Not proof, but an indication that rules out a completely different origin of the drawing and supports the overall picture.

Still much to discover

Next, the researchers want to try to “resolve” the DNA data higher using telomere-to-telomere sequencing, to compare hundreds of thousands of base pairs instead of 90,000. In parallel, work is underway on bones that could belong to da Vinci's relatives. Furthermore, 14 living relatives of the Renaissance star were identified a few years ago.

This is not surprising: although the Florentine, as far as is known, had no children, he had at least 22 half-siblings on his father's side and probably five on his mother's side. Unfortunately, the whereabouts of the mother's mortal remains are unknown, otherwise the DNA hunters would have had a much easier time: mitochondrial traces are often more frequent and thus easier to find and process, but they trace back exclusively to the mother.

Although it will probably never be possible to assign da Vinci's DNA with complete certainty, the research group has laid a foundation for the analysis of the bio-signatures of centuries-old artworks. The pictorial panels at the end of the preprint paper illustrate how differentiated these are. Even for non-experts.

Researchers from the USA, Switzerland, Austria, Italy, and Spain were involved. The lead researchers were Harinder Singh, Seesandra V. Rajagopala, Rebecca Hart, Pille Hallast, and Mark Loftus.

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