PULLMAN, WASHINGTON—The International Business Times reports that a team led by Shannon Tushingham of Washington State University, working in cooperation with members of the Ohlone tribe in the San Francisco Bay Area, used liquid chromatography-mass spectrometry to look for evidence of nicotine, caffeine, and atropine in plaque obtained from the teeth of eight people buried between 6,000 and 300 years ago in what is now California. In the past, archaeologists have relied upon the presence of pipes, charred tobacco seeds, and analysis of hair and fecal matter to trace the spread of tobacco in the ancient Americas. Two of the samples, collected from a man who had been buried with a pipe and an older women, tested positive for nicotine. Jelmer Eerkens of the University of California, Davis, said the woman’s age supports the idea that younger women may have avoided intoxicants in order to protect infants, while older women used the substances. The team plans to additional tests to look for other intoxicating chemicals in dental plaque. To read in-depth about research on ancient dental plaque, go to “Worlds Within Us.”