Ancient Dental Plaque Is Changing What We Know About Medieval Diets

For decades, archaeologists have relied on chemical signatures locked inside ancient bones to reconstruct what people once ate. But those techniques have a blind spot: foods consumed occasionally or in small amounts often disappear from the record entirely.

Now, a new biomolecular approach is pulling those missing meals back into view using something we usually want to get rid of – dental plaque.

In a study published in Scientific Reports, researchers analyzed dental calculus from medieval human remains in Ukraine and uncovered the first direct molecular evidence of trace-level millet consumption. The findings don’t just add a new ingredient to the medieval menu, they also signal a major shift in how scientists can study ancient diets.

Analyzing the Secrets Hidden in Dental Calculus

Dental calculus, the mineralized plaque that builds up on teeth over time, is increasingly recognized as a powerful archaeological archive. Unlike bone, it traps tiny remnants of food, microbes, and environmental particles during a person’s lifetime.

In this study, researchers applied thermal desorption-gas-chromatography-mass spectrometry (TD-GC/MS) to dental calculus samples weighing only a few micrograms, which is far smaller than what other techniques require for analyses.

Using this method, the team identified miliacin, a molecular compound uniquely abundant in broomcorn millet, in eight individuals buried at the medieval site of Ostriv in Ukraine. The ability to detect this specific biomarker at such small scales marks a substantial methodological leap.

“Our findings demonstrate that even the smallest traces of millet leave molecular fingerprints in dental calculus. This opens up an entirely new way to detect subtle dietary practices in the past,” said co-lead author Shinya Shoda in a press release.

The new approach is fast, minimally destructive, and adaptable to a wide range of archaeological contexts, making it especially attractive for analysis of rare or fragile remains.

Read More: Ancient Teeth Carry Clues on Farming Villages That Welcomed Outsiders with Open Arms

What Did Dental Calculus Show About Medieval Diets?

By combining molecular data with traditional isotopic analysis, the researchers uncovered strikingly varied dietary histories among individuals.

“Dental calculus is a biological material often found on human teeth. Finding species-specific plants in the calculus matrix in combination with other biomolecular archaeological techniques opens a new possibility to understand the nutrition of past populations,” explained Aleksandra Kozak.

Several people showed clear molecular evidence of millet consumption even though their isotopic values suggested otherwise. In some cases, the isotope signatures reflected little childhood exposure to millet, implying that these individuals may have adopted millet later in life, possibly due to migration, shifting cultural practices, or changes in food availability.

How This Method Will Change Archaeology

Traditional stable isotope analysis typically detects millet only when it accounts for more than 20 percent of a person’s dietary protein. That threshold means lower levels of seasonal or socially specific consumption often go unnoticed.

By revealing the presence of unidentified foods, dental calculus analysis could reshape how researchers understand dietary diversity across history.

“This technique allows us to access underrepresented plant foods that rarely appear in the archaeological record,” said co-lead author Giedrė Motuzaitė Matuzevičiūtė. “It gives us a clearer picture of everyday diets and how people adapted to local environments and cultural changes.”

Beyond millet, the method also holds promise for identifying other economically or medicinally important plants, offering a far more nuanced view of how ancient societies fed themselves, one tooth at a time.

Read More: Ancient Dirty Dishes May Be Misleading Archaeologists and Rewriting History

Article Sources

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• This article references information from a study published in Scientific Reports: Thermal desorption GC/MS on human dental calculus detected minute millet consumption in medieval Ukraine