Researchers have shown, for the first time, that nicotine residue can be extracted from plaque on the teeth of ancient tobacco users. Their work provides a new method for determining who was consuming tobacco in the ancient world and could help trace the use of tobacco and other intoxicating plants further back into prehistory.
“The ability to identify nicotine and other plant-based drugs in ancient dental plaque could help us answer longstanding questions about the consumption of intoxicants by ancient humans,” said Shannon Tushingham, PhD, assistant professor of anthropology at Washington State University and co-author of the study. “For example, it could help us determine whether all members of a society used tobacco, or only adults, or only males or females.”
Tracing the spread of tobacco in the America’s has traditionally relied on the presence of pipes, charred tobacco seeds, and the analysis of hair and fecal matter. However, these items are rare in the archaeological record and are hard to link to particular individuals. As a result, tobacco use has been difficult to document archeologically.
Dental plaque adheres to tooth surfaces and mineralizes over time, though, preserving a wide range of substances in the mouth. It is easy to link to particular individuals because it can be removed directly from teeth. Still, archeologists have ignored plaque until recently.
Using modern, sensitive instrumentation, scientists can detect and characterize trace amounts of a wide variety of compounds, including proteins, bacterial DNA, starch grains, and other plant fibers in dental plaque. And because nicotine is detectable in the plaque of contemporary smokers, the researchers wanted to find out if it also was preserved in plaque taken from people who lived long ago.
The researchers extracted plaque from the teeth of eight individuals buried between 300 and 6,000 years ago and analyzed it for nicotine. Using ordinary dental picks, they extracted the plaque from the ancient teeth and used liquid chromatography-mass spectrometry to test the samples for nicotine, caffeine, and atropine.
Two samples tested positive for nicotine, demonstrating for the first time that the drug can survive in detectable amounts in ancient plaque. One of these individuals, an adult man, was buried with a pipe. A surprise came from the molar of an older woman that also tested positive for nicotine.
“While we can’t make any broad conclusions with this single case, her age, sex, and use of tobacco is intriguing. She was probably past child-bearing age and likely a grandmother,” said Jelmer Eerkens, PhD, an anthropologist at the University of California, Davis.
“This supports recent research suggesting that younger adult women in traditional societies avoid plant toxins like nicotine to protect infants from harmful biochemicals, but that older women can consume these intoxicants as needed or desired,” said Eerkens.
While the researchers did not detect evidence of any other plant-based drugs in this particular study, they believe dental plaque could be used to help trace the use and spread of other intoxicants as well.
“We think a wide variety of plant-based, intoxicating chemicals could be detected in ancient dental plaque,” said Korey Brownstein, a graduate student in the Washington State University Molecular Plant Sciences Program. “It really opens up a lot of interesting avenues of discovery.”