Chilled to minus 40 degrees F-colder, even, than the Mongolian winter-the collection includes everything from eezgi and byaslag to goat turds and yak-udder swabs. Even their metaphors are dairy-based: “The smell from a wooden vessel filled with milk never goes away” is the rough equivalent of “old habits die hard.”ĭown the hall from the ancient DNA lab, thousands of microbiome samples the team has collected over the past two summers pack tall industrial freezers. They include it in festivities and offer it to spirits before any big trip to ensure safety and success. Though it’s estimated that just 1 in 20 Mongolians has the mutation allowing them to digest milk, few places in the world put as much emphasis on dairy. Samples of the microbiome from in and around today’s herders, Warinner realized, might offer a way to understand how this was possible. Ancient plaque shows Mongolians have eaten dairy for millennia. But, Warinner says, direct evidence of long-ago dairy consumption was absent-until ancient calculus let her harvest it straight from the mouths of the dead. Mongolia made sense: There’s evidence that herding and domestication there dates back 5,000 years or more. To prove it, she began looking for places where the situation was similar. Warinner guessed that microbes may have been doing the job of dairy digestion for them. For 4,000 years prior to the mutation, Europeans were making cheese and eating dairy despite their lactose intolerance. Ancient DNA samples from all across Europe suggest that even in places where lactase persistence is common today, it didn’t appear until 3000 BCE-long after people domesticated cattle and sheep and started consuming dairy products. Until recently, geneticists thought that dairying and the ability to drink milk must have evolved together, but that didn’t prove out when investigators went looking for evidence. It’s here that many of Warinner’s Mongolian specimens get cataloged, analyzed, and archived. Inside, postdocs and technicians wielding drills and picks harvest fragments of dental plaque from the teeth of people who died long ago. To prevent any errant DNA from contaminating its samples, entering the lab involves a half-hour protocol, including disinfection of foreign objects, and putting on head-to-toe Tyvek jumpsuits, surgical face masks, and eye shields. Nowadays, Warinner does her detective work at the Max Planck Institute for the Science of Human History’s ancient DNA lab, situated on the second floor of a high-rise bioscience facility overlooking the historic center of the medieval town of Jena, Germany. Understanding the differences between traditional microbiomes like theirs and those prevalent in the industrialized world could help explain the illnesses that accompany modern lifestyles-and perhaps be the beginning of a different, more beneficial approach to diet and health.
By scraping gunk off the teeth of steppe dwellers who died thousands of years ago, she’s been able to prove that milk has held a prominent place in the Mongolian diet for millennia. Warinner is convinced that the Mongolian affinity for dairy is made possible by a mastery of bacteria 3,000 years or more in the making.