Multiproxy analysis exploring patterns of diet and disease in dental calculus and skeletal remains from a 19th century Dutch population

## Abstract

Dental calculus is an excellent source of information on the dietary patterns of past populations, including consumption of plant-based items. The detection of plant-derived residues such as alkaloids and their metabolites in dental calculus provides direct evidence of consumption by individuals within a population.
We conducted a study on 41 individuals from Middenbeemster, a 19th century rural Dutch archaeological site. Skeletal and dental analysis was performed to explore potential relationships between pathological conditions/lesions and the presence of alkaloids. We also explored other factors potentially affecting the detection of alkaloids, including sample weight and skeletal preservation. Dental calculus was sampled and analysed using ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-ESI-MS/MS).
We were able to detect nicotine, cotinine, caffeine, theophylline, and salicylic acid. By detecting these compounds we are able to show the consumption of tea and coffee and smoking of tobacco on an individual scale, which is also confirmed by historic documentation and identification of pipe notches in the dentition. Nicotine and/or cotinine was present in 60% of individuals with at least one visible pipe notch. We find some influence of skeletal preservation on the detection of alkaloids and salicylic acid, with higher quantities of compounds extracted from well-preserved individuals, and also observe a relationship between weight of the calculus sample and raw quantity of the detected compounds, and we were able to detect alkaloids in samples as small as 2 mg. We found correlations between chronic maxillary sinusitis and the presence of multiple alkaloids.We show that there are many limitations that will need to be addressed going forward with this type of analysis, and stress the need for more systematic research on the consumption of alkaloid-containing items and their subsequent concentration and preservation in dental calculus, in addition to how mode of consumption may affect concentrations on different parts of the dentition.
Despite the limitations, this preliminary study illustrates the many benefits of using calculus to target a variety of compounds that could have been ingested as medicine or diet, or consumed in a different manner. This method allows us to directly address specific individuals, which can be especially useful in individuals that are not always well-documented in historic documentation, such as rural populations, children and women.