Dental calculus as a source of ancient alkaloids: Detection of nicotine by LC-MS in calculus samples from the Americas

Dental calculus has been shown to be a repository of a variety of exogenous organic materials, including bacterial DNA, proteins, phytoliths, and starch grains. Here we show that certain alkaloids, nicotine in this case, can also be trapped and preserved in ancient dental calculus. We present Ultra-Performance Liquid Chromatography-Mass Spectrometry (UPLC-MS) results of analyses of ten archaeological calculus samples from eight individuals from Central California. Two samples tested positive for the presence of nicotine, including one from an individual buried with a pipe. UPLC-MS analyses of dental calculus could provide an alternative means to trace the spread and consumption of tobacco and other plants with distinctive alkaloid products in ancient societies. As shown here for the first time in ancient samples, the ability to detect nicotine alkaloids in calculus has enormous potential to help us better understand the consumption of intoxicant plants by ancient humans on the individual level, for example by giving us the ability to test assumptions about the age, sex, and status of individual tobacco users in the past.