In DepthHUMAN EVOLUTION

Early Mongolians ate dairy, but lacked the gene to digest it

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Science  09 Nov 2018:
Vol. 362, Issue 6415, pp. 626-627
DOI: 10.1126/science.362.6415.626

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Summary

More than 3000 years ago, herds of horses, sheep, and cows or yaks dotted the steppes of Mongolia. Their human caretakers ate the livestock and honored them by burying animal bones with their own. Now, a cutting-edge analysis of deposits on ancient teeth shows these early Mongolians milked their animals as well. That may not seem surprising. But DNA analysis of the same ancient individuals shows that as adults they lacked the ability to digest lactose, a key sugar in milk. The findings present a puzzle, because they suggest dairying and lactose tolerance may be disconnected. That challenges an oft-told tale of how this adaptation evolved and spread in populations in Europe and Africa. Mongolians' fondness for fermented milk products—using bacteria to help them digest lactose—may help explain the riddle.