World's Oldest Cheese Has Secrets to Tell

In the 1990s, archaeologists peered into the graves of 3,600-year-old mummies in a desert in northwest China's Xinjiang region and found a strange substance smeared on their heads and necks. It turned out to be the oldest cheese ever found, and it's taught researchers quite a bit about the diet and habits of the ancient Xiaohe people, who apparently enjoyed fermented cheese as "a snack packed for the afterlife," per CNN. In a groundbreaking genomic analysis, researchers led by Chinese paleogeneticist Qiaomei Fu sequenced DNA from the cheese and discovered it had been made with goat and cow milk and a yeast and bacterial mixture called kefir, which is still used to make probiotic-rich cheese and yogurt.

The cheese contained multiple bacterial and fungal species, including Lactobacillus kefiranofaciens and Pichia kudriavzevii, both of which are found in modern kefir grains. One major group of Lactobacillus bacteria originated in Russia and is widely used globally. But the Lactobacillus bacteria in the ancient cheese is more closely related to a second major group that originated in Tibet and spread from Xinjiang to inland East Asia, according to the study published Wednesday in the journal Cell. This "unprecedented study, allowing us to observe how a bacterium evolved over the past 3,000 years ... suggests kefir culture has been maintained in ... [the] Xinjiang region since the Bronze Age," Fu says in a statement, per Live Science and CNN.

Harvard University anthropologist Christina Warinner, who wasn't involved in the study, notes that without refrigeration, milk would've undergone "spontaneous fermentation" within a few hours, ultimately making it more easily digestible, per CNN. To make kefir cheese just as traditional producers do today, the Xiaohe people would've added "previously made kefir grains (similar to kombucha mother or bread starter) that was passed on through family, friends and other social contact," says University of Arkansas anthropologist Taylor Hermes, who's also unaffiliated with the research. "This is what makes the study so important—we can see how these microbial commodities were handed down and spread throughout Asia." (More discoveries stories.)