Cheese dating back 3,600 years has been discovered in the Xiaohe cemetery of China's Taklamakan Desert, providing a unique window into the past. This ancient dairy product, found scattered on the heads and necks of Bronze Age mummies, is the oldest cheese ever found and offers a tantalizing glimpse into the culinary practices of the Xiaohe people.

The Xiaohe mummies, naturally preserved by the arid desert conditions, were buried with their cheese, possibly as a provision for the afterlife. This discovery, a decade in the making, has allowed scientists to extract and sequence DNA from the ancient cheese, revealing insights into the microbial processes used in its creation.

Deciphering the Secrets of the Past

The analysis of the ancient cheese has opened a new frontier in ancient DNA studies, as stated by Christina Warinner, an anthropologist at Harvard University. "Fermented foods today are overwhelmingly produced using only a handful of mostly lab-grown commercial strains of bacteria and yeasts," she noted. This discovery sheds light on the diverse range of microbes once used to produce iconic foods.

Led by Chinese paleogeneticist Qiaomei Fu, the research team identified goat and cattle DNA in the cheese samples and sequenced the DNA of the microbes within it, confirming it as kefir, a cheese still widely made and consumed today. Fu's work at the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing has been instrumental in this groundbreaking study.

Cultural and Biological Insights

The Xiaohe people's cheese-making process did not involve mixing different types of animal milk, a practice common in traditional Middle Eastern and Greek cheesemaking. Instead, they likely used kefir grains passed down through social contacts, similar to the way traditional kefir cheese is made today.

The cheese samples contained bacterial and fungal species, including Lactobacillus kefiranofaciens and Pichia kudriavzevii, both commonly found in present-day kefir grains. This finding challenges the long-held belief that kefir originated solely in the Caucasus Mountains region, suggesting a more complex history of cultural and biological exchange.

Evolution of Probiotic Bacteria

The study also provided insights into the evolution of probiotic bacteria over the past 3,600 years. The ancient Lactobacillus kefiranofaciens was found to be closely related to a less common group of Lactobacillus originating in Tibet. This discovery expands our understanding of the global spread of dairy products and the evolution of the bacteria used in their production.

The successful DNA sequencing of the ancient cheese is remarkable, given the technical challenges of ancient DNA analysis, particularly the risk of contamination by modern bacteria. The process of fermentation, which makes milk more digestible, was likely crucial for these ancient people, who lacked refrigeration.

Implications for the Future of Dairy

This unprecedented study not only allows us to observe the evolution of a bacterium over thousands of years but also provides a clearer picture of ancient human life and their interactions with the world. The genomic analysis performed by Fu's team is groundbreaking, revealing the complexity of the products that were once a foundation of life and continue to be important today.

While the cheese found with the mummies is the oldest intact cheese in the archaeological record, other evidence suggests that cheesemaking may have originated much earlier, potentially more than 9,000 years ago in Anatolia or the Levant. These incredible findings highlight the enduring significance of dairy products in human culture and their role in shaping our culinary history.