JENA, GERMANY—According to a Science News report, adults who lived in what is now Mongolia some 3,000 years ago drank the milk of cows, yaks, and sheep, even though they did not possess genes for digesting lactose. Christina Warinner of the Max Planck Institute for the Science of Human History and her colleagues found milk proteins in dental plaque obtained from skeletons recovered from 22 burial mounds left by the Deer Stone people of Mongolia’s eastern steppes. The Deer Stone people may have been able to digest milk due to bacteria in the gut, just as present-day Mongolians are, Warinner explained. To read in-depth about Warinner's research on ancient dental plaque, go to “Worlds Within Us.”