New biomolecular technique reveals species specific plant consumption in human dental calculus of medieval Ukraine

Detecting What Isotopes Miss

“Our findings demonstrate that even the smallest traces of millet leave molecular fingerprints in dental calculus,” said Dr Shinya Shoda, co-lead author from the Nara National Research Institute for Cultural Properties. “This opens up an entirely new way to detect subtle dietary practices in the past.”

Traditional stable isotope analysis can identify millet consumption only when it makes up more than ~20% of an individual’s dietary protein. As a result, low-level or occasional millet consumption, especially common in seasonal, opportunistic, or socially variable diets, often goes unnoticed. In this study, several individuals with clear miliacin signals showed depleted δ¹³C values, suggesting that conventional isotopic analyses would have overlooked their intake of C4 plants such as millet. In other words, the conventional isotopic approach would have suggested that these people did not eat millet at all – while the molecular evidence clearly shows they did. This highlights how easily such subtle dietary signals can be missed by traditional methods.

A New Tool for Reconstructing Ancient Diets

The successful use of TD-GC/MS on microgram-scale samples – far smaller than previously possible – marks a significant methodological advance. The approach is efficient, minimally destructive, and broadly applicable across archaeological contexts.

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

Insights into Medieval Communities

The medieval population of Ostriv, part of the Kievan Rus’ cultural sphere and influenced by both Slavic and Baltic communities, showed variable dietary histories. In several individuals, miliacin was found despite isotope signatures reflecting little childhood exposure to millet: suggesting adoption of millet consumption later in life, possibly linked to migration or changing food availability.

“Dental calculus is a biological material often found on human teeth. Finding species-specific plants in the calculus matrix in combination with other biomolecular archaeology techniques” opens a new possibility to understand the nutrition of past populations,” says the anthropologist of the study, Dr Aleksandra Kozak from the Institute of Archaeology in Kyiv.

This study highlights the transformative potential of dental calculus analysis for identifying ancient plant use. The new methodology may reshape our understanding of dietary diversity across time, geography, and social identities. This research will also be vital in understanding processes of dietary shifts to new crop consumption in various societies before they become ubiquitous. “This study also holds immense potential for identifying biomolecules of other underrepresented plants of economic and medicinal importance”, said Prof. G. Motuzaitė Matuzevičiūtė.

This research was supported by the European Research Council Consolidator Grant “MILWAYS – Past and Future Millet Foodways” (101087964), awarded to Prof. Motuzaitė Matuzevičiūtė at Vilnius University, the Mitsubishi Foundation Research Grants in the Humanities awarded to Dr Shoda (SOUP, 202420018) and the “Baltic migrants at the border of the Kievan Rus” German Science Foundation (DFG) project P508078428 represented by Dr Kozak’s contribution.

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