In Search of the Missing Microbe

Most Mongolians are lactose intolerant, and yet their diet relies on dairy. A mysterious world of bacteria could be at play.

- Andrew Curry

Lake Khövsgöl is about as far north of the Mongolian capital of Ulaanbaatar as you can get without leaving the country. If you’re too impatient for the 13-hour bus ride, you can take a prop plane to the town of Murun, then drive for three hours on dirt roads to Khatgal, a tiny village nestled against the lake’s southern shore. The felt yurts that dot the surrounding green plains are a throwback to the days—not so long ago—when most Mongolians lived as subsistence herders.

In July 2017, archaeogeneticist Christina Warinner headed there to learn about the population’s complex relationship with milk. In Khatgal, she found a cooperative called Blessed by Yak, where families within a few hours’ drive pooled the bounty from their cows, goats, sheep, and yaks to supply tourists with heirloom dairy products.

Warinner watched for hours as Blessed by Yakmembers transformed the liquid into a dizzying array of foods. Milk was everywhere in and around these homes: splashing from swollen udders into wooden buckets, simmering in steel woks atop fires fueled by cow dung, hanging in leather bags from riblike wooden rafters, bubbling in specially made stills, crusting as spatters on the wood-lattice inner walls. The women even washed their hands in whey. “Working with herders is a five-senses experience,” Warinner says. “The taste is really strong; the smell is really strong. It reminds me of when I was nursing my daughter, and every thing smelled of milk.”

Each family she visited had a half-dozen dairy products or more in some stage of production around a central hearth. And horse herders who came to sell their goods brought barrels of airag, a slightly alcoholic fizzy beverage that set the yurts abuzz.