A groundbreaking discovery has unveiled the world’s oldest known cheese sample, dating back to 3,600 years ago. Found on ancient Chinese mummies in the Tarim Basin, this kefir cheese provides new insights into the origins of this fermented dairy product and the evolution of probiotic bacteria.

Archaeologists first stumbled upon the unusual white substance nearly two decades ago, but its exact nature remained a mystery until recent advancements in DNA analysis. Led by Qiaomei Fu, researchers from the Chinese Academy of Sciences identified the substance as kefir cheese, a fermented dairy product made from cow and goat milk.

The ancient Xiaohe people used separate batches of cow and goat milk for their cheese-making, unlike the mixed milk traditions found in other regions. Genetic analysis revealed that the cheese contained specific bacteria and yeast, including Lactobacillus kefiranofaciens and Pichia kudriavzevii, commonly found in modern kefir grains.

One of the most significant findings was the discovery that the Lactobacillus kefiranofaciens in the ancient cheese was closely related to a strain found in Tibet. This challenges the long-held belief that kefir originated solely in the Caucasus Mountains of Russia. The study suggests that kefir culture may have been maintained in northwestern China since the Bronze Age.

The ancient kefir cheese also contained higher levels of Lactobacillus kefiranofaciens than modern varieties, which would have made it more likely to trigger immune responses in the human digestive system. Over time, the bacteria seem to have evolved alongside humans, becoming less likely to cause such reactions.

The presence of kefir cheese in the Xiaohe tombs raises intriguing questions about its significance in ancient burial practices. While the exact reason for smearing cheese on the mummies remains unclear, it may have served as a delicacy for the deceased in the afterlife or played a ritualistic role in the burial process.

This groundbreaking discovery offers valuable insights into the diet, culture, and scientific practices of our ancestors. By studying ancient food artifacts like this kefir cheese, researchers can piece together the complex tapestry of human history and the evolution of our foodways.