Evrim Yazgin
Cosmos science journalist
Ever had an aged cheddar or parmesan that was extra sharp and thought – how old is too old for cheese? Well, the aging just got a whole lot longer.
A cheese found in northwestern China is 3,600 years old and is the subject of a paper published today in the journal Cell.
If that’s not enough to spoil your appetite, the scientists report that the cheese was found alongside mummified corpses in the Tarim Basin in Xinjiang province.
Luckily, they resisted the urge to have a nibble, instead subjecting the Bronze Age cheese to a smorgasbord of tests.
“This is the oldest known cheese sample ever discovered,” says corresponding author Qiaomei Fu, from the Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences.
“Food items like cheese are extremely difficult to preserve over thousands of years, making this a rare and valuable opportunity. Studying the ancient cheese in great detail can help us better understand our ancestors’ diet and culture,” she adds.
Previously, the oldest cheeses in the world were found in Egypt. They dated to between 3,200 and 2,900 years ago.
The find came in a surprising way. About 20 years ago, archaeologists noticed mysterious white substances smeared on the heads and necks of several mummified bodies in the Tarim Basin’s Xiaohe cemetery in northwestern China. The bodies are 3,300–3,600 years old.
The archaeologists realised it might be a kind of fermented dairy product, but its identity eluded them until now.
Analysis revealed cow and goat DNA in the cheese samples. Unlike in many Middle Eastern and Mediterranean cheese-making techniques, the ancient Xiaohe people used different types of animal milk in separated batches.
Further DNA analysis revealed that the cheese is kefir which is common today in western Eurasia.
Fu and her colleagues identified bacterial and fungal species as well, including Lactobacillus kefiranofaciens and Pichia kudriavzevii, both commonly found in present-day kefir grains which are used to initiate fermentation.
Kefir grains are symbiotic cultures. They contain multiple species of probiotic bacteria and yeast which ferment milk into kefir cheese.
Finding the ancient bacteria is an opportunity to study the evolution of these organisms.
There are 2 main groups of Lactobacillus bacteria today – one originating in Russia and another from Tibet. The Russian type is the most widely used globally for making yogurt and cheese.
The team found that the ancient L. kefiranofaciens was more closely related to the Tibetan group, challenging the long-held belief that kefir originated solely in the North Caucasus Mountain region of modern-day Russia.
“Our observation suggests kefir culture has been maintained in Northwestern China’s Xinjiang region since the Bronze Age,” Fu says.
“This is an unprecedented study, allowing us to observe how a bacterium evolved over the past 3,000 years. Moreover, by examining dairy products, we’ve gained a clearer picture of ancient human life and their interactions with the world,” says Fu.
