A few years back, archaeologist Anna Dhody was thinking about how amazing it is that DNA forensic scientists can collect DNA evidence from nothing more than a discarded cigarette butt or paper cup. If there is enough DNA clinging to those modern-day objects to identify the people who used them, she reasoned, maybe some of the artifacts at the museum where she worked could yield genetic clues to ancient mysteries.That’s when she and her boss at Harvard University’s Peabody Museum began rummaging through the institution’s collections looking for quids. Quids are little bundles of yucca fiber that were chewed and discarded by people who lived more than 1,000 years ago in what is now the southwestern United States.Where there’s chewing, there’s spit. And where there’s spit, there’s DNA. According to an article in this month’s issue of The Scientist, Dhody and her boss eventually succeeded in extracting and testing mitochondrial DNA from a number of quids and other artifacts from the Southwest. Mitochondrial DNA is especially useful for tracing ancestral relationships between groups of people — and what came from the quids suggested that the people who lived in the Southwest between about 1,000 and 2,000 years ago were descended from central Mexican farmers who had migrated northward a few millennia before.Dhody, who is now curator of the MÃ¼tter Museum in Philadelphia, and her boss Stephen LeBlanc, the director of collections at the Peabody Museum, describe their work in the Summer 2007 Journal of Field Archaeology.