Around 60,000 years ago in Siberia, a Neanderthal opened their mouth so that a rotten tooth could be drilled — and the case is the oldest evidence of an intentional dental treatment to date, a new study finds.

A lower molar tooth belonging to a Neanderthal adult was originally unearthed in 2016, but it was not clear what had caused the deep hole in its surface. Now, experimental evidence indicates the hole was made with a small stone drill used to clean out bits of severely rotten tooth tissue, according to a study published in the journal PLOS One.

This intricate procedure shows Neanderthals — our closest human relatives who lived from around 400,000 to 40,000 years ago — had the brains to recognize this painful tooth cavity could be treated and possessed the fine motor skills to successfully execute the procedure.

“The fact that this invasive treatment took place and the person survived lends me to believe that this is another example of the really very sophisticated Neanderthal understanding of human biology and when you need to intervene,” study co-author John W. Olsen, a professor emeritus of anthropology at the University of Arizona, told Live Science.

It’s unclear whether this was self-treatment or dentistry performed by another individual. Even so, “it suggests that the roots of invasive medicine and surgery do not belong exclusively to Homo sapiens, but are part of a broader legacy shared with our closest relatives,” Gregorio Oxilia, an associate professor of human anatomy at the Free Mediterranean University in Italy who was not involved in the research, told Live Science in an email.

The oldest evidence of our own species, Homo sapiens, treating tooth decay dates to roughly 14,000 years ago in what is now Italy. By pushing back the date of intentional dentistry by roughly 45,000 years, this new finding “fundamentally reshapes our understanding of the evolution of human healthcare,” said Oxilia, who was the first author on the study detailing the 14,000-year-old finding.

However, in part because their generally low-carbohydrate diets kept the rates of tooth decay low, evidence of dental interventions in Neanderthals has been limited. So, to determine whether the unusual hole in the roughly 59,000-year-old Neanderthal molar found in Chagyrskaya Cave was deliberately human-made, the researchers inspected the tooth and ran experiments using three modern human teeth.