Photo Credit: Dr. Christina Warinner
Photo Credit: Dr. Christina Warinner

By Emma Yasinski

She lived in Dalheim, Germany, roughly between A.D. 997 and 1162. She was religious. And in all likelihood, she worked illustrating sacred texts and decorating their pages, an art long believed to be the exclusive domain of monks.

No record of her survives, but her medieval skeleton and intact teeth are rewriting the history of that period, and may very well change the way that archeologists study historical artifacts.

Christina Warinner, PhD, a group leader in the microbiome sciences at Germany’s Max Planck Institute for the Science of Human History, and then-grad student Anita Radini, PhD (now a research fellow at the University of York), were searching for clues about diet, oral health, and microbiome health in the dental calculus of people from medieval times.

“The initial study really set out to characterize the periodontal disease in these individuals and the bacteria contributing to it, using genetic approaches,” Dr. Warinner told Incisor. “We discovered that dental calculus is actually the richest source of aged DNA known in the entire archeological record.”

Researchers are comfortable with the standard analytical methods, which include microscopy and analyzing DNA found in the calculus for evidence of bacteria consistent with periodontal disease and certain dietary items, such as wheat. Dr. Warinner often used a weak acid to help break up the dental calculus and show what’s inside.

Normally, a scientist will set up the acid to wear away the calculus, then come back when it’s done to see the results. But according to Dr. Warinner, Dr. Radini was especially conscientious and decided to stay for a while to make sure everything was running smoothly. That was when she witnessed something that shocked both researchers.


“That was something we had not been expecting,” recalled Dr. Warinner. “It's something, frankly, we've never seen before.”


Dr. Radini immediately called Dr. Warinner to tell her there were mysterious, bright blue particles that appeared, but then began disappearing after a few hours while the acid worked. “It was extremely unusual that it was all these blue particles, really bright blue particles in the calculus. And that was something we had not been expecting,” recalled Dr. Warinner. “It's something, frankly, we've never seen before.”

In order to observe the particles and determine their origin, the team needed a new way to release them from the dental calculus. The traditional protocol would strip the material away and make it impossible to analyze.


“We had to develop a completely new way of breaking up the calculus so that it didn't damage the pigments inside,” said Dr. Warinner. “We're now advocating for an alternative method for analyzing calculus that preserves things like these mineral particles.”

It’s possible that the conventional method has erased evidence from previous samples of dental calculus, or maybe even art or other historical artifacts, she explained. They identified the blue material as lapis lazuli, a material that was as valuable as gold in medieval times and was used in important manuscripts.


“The more we work with teeth, the more interesting we find them to be.”


Photo: Dr. Christina Warinner (
Photo: Dr. Christina Warinner (

Based on this finding, the team suggested a few possibilities about the woman’s life. They believe the most likely scenario is that she was a skilled scribe. That would make her one of a few nuns known to have been entrusted with such work.

Dr. Radini has since graduated and gone on to start her own lab where she plans to focus on using the technique (and optimizing others) to explore the dental calculus for evidence of what she calls “dusty crafts,” or historical professions and hobbies.

While Dr. Warinner believes the lapis lazuli finding is unlikely to be directly relevant to dental health today, she did say, “We're starting to look deeper into the past to really understand how oral health has changed through time. And I think this is going to give us some new insights on how we can better manage oral health today.” Dr. Warinner added, “the more we work with teeth, the more interesting we find them to be … archeologists are ready and waiting to collaborate with [dentists].”


Author: Contributing writer Emma Yasinski received her Master of Science (MS) in science and medical journalism from Boston University. Her articles have also appeared at, Kaiser Health News, NPR Shots, and Genetic Engineering and Biotechnology News.

Other Recent Incisor Articles by Emma Yasinski:

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