Uncovered in a Chinese mummy's remains: Century-old kefir dairy product.
Kefir, a well-known beverage originating from the Caucasus region, was being manufactured in ancient China around 3500 years ago, as proven by the examination of remnants found on mummies' heads and necks. This discovery suggests the dissemination of kefir from the North Caucasus to Europe and other regions, as documented in the journal "Cell". Furthermore, it seems there was another route of spread from Xinjiang in western China to other interior regions of East Asia such as Tibet.
Studies show that the number of microbes in fermented foods can be up to 10,000 times higher than in fresh ones. Probiotic bacteria like certain Lactobacillus species are linked to various health advantages in the gut, impacting the immune system and potentially decreasing the risk of infections and inflammation.
Ancient Practices
There are records of milk fermentation dating back to 6000-4000 BCE in India, and populations in the Mediterranean region were already producing and consuming cheese 7000 years ago.
A team led by Qiaomei Fu from the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences in Beijing analyzed kefir cheese crumbs found on mummies in a site in the Tarim Basin in Xinjiang. The mummies with dairy products were found at the Xiaohe Cemetery in Xinjiang two decades ago.
"Foods like cheese are incredibly challenging to preserve for thousands of years, making this a rare and valuable discovery," Fu explained.
Kefir is a thick, fermented milk product produced through a process involving milk acid bacteria and yeasts, which can also be used to make cheese.
Reduced Lactose and Stomach Discomfort
A 2021 study revealed that the builders of the Xiaohe burial site were lactose intolerant. By manufacturing a milk product that largely consumed lactose, people could consume milk as food without experiencing digestive issues, according to Fu and colleagues. Additionally, kefir is more durable than raw milk.
Modern technology now enables the genetic analysis of ancient kefir cheese. The milk in two of the examined samples was from cows, and in another from goats. Due to the small sample size, it's unclear if ancient kefir producers also mixed cow and goat milk, as is common in Greece and the Middle East today.
The goat species from which the milk came belongs to a genetic lineage of goats that was widespread in Eurasia after the Neolithic period.
More Robust and Resilient
The researchers also found the genetic material of numerous microorganisms, primarily bacteria and fungi. They examined the genome of the bacterium Lactobacillus kefiranofaciens, which is present in modern kefir, and compared it to current bacterial cultures. These have evolved over time: they are better protected against antibiotic toxins and more resilient.
Adaptations in the bacterial cell wall likely made them more tolerant to the human gut. Here, humans may have played a role in evolutionary development by selecting more tolerant strains, scientists suggest.
The analysis of kefir cheese crumbs on Xinjiang mummies revealed that 'The case' of ancient dairy production in China was more complex than initially thought, with evidence suggesting both North Caucasus and Xinjiang as potential sources of kefir spread.
Furthermore, the study showed that ancient kefir was made from both cow and goat milk, demonstrating that 'The case' of milk utilization in ancient societies was diverse and adaptive, catering to various dietary needs and preferences.
