Without a doubt, the history of cheese has just taken a great leap forward. A Chinese team has managed to extract DNA from the oldest dairy product residues ever discovered. These solid samples, a few centimeters wide, exhumed from a 3,500-year-old tomb in a cemetery in Xinjiang, provide essential information, both on the spread of this dietary practice and on the evolution of the composition of kefir grains. used for fermentation. Published in the magazine cellon September 25, these results promise to be widely discussed by both paleontologists and food specialists.
Located east of the Takla-Makan Desert in the Uyghur Autonomous Region, Xiaohe Cemetery is an exceptional site. Discovered at the beginning of the 20th century, it took off scientifically at the beginning of the 21st, when Chinese archaeologists unearthed some three hundred burials from the Bronze Age, aged between 3,300 and 3,600 years, of which 167 were searched. In most of them, researchers found mummified bodies, but also thousands of objects, plant extracts and what looked like fragile pebbles. Placed around the neck of the deceased, like stones in a necklace, or along the body, they aroused the curiosity of all scientists.
In 2014, a first Chinese team managed to make proteins speak: they are dairy products. And not just any bacteria: the joint presence of already known bacteria and yeasts offers the signature of kefir, this fermentation method used for millennia to prepare, among other things, milk or fruit-based drinks.
“Technological feat”
But proteins only offer fragmented information. In order to actually read cheese residues, DNA is needed. Extracting this genetic code from such ancient samples, contaminated for thousands of years by other microorganisms, then seems impossible. However, this is what Qiaomei Fu, head of the former DNA laboratory at the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences, and his team achieved.
“A true technological feat”greets biophysicist Christophe Lavelle, researcher at the National Museum of Natural History in Paris, whose laboratory is developing a project on kefir and its history. The latter requires the development of specific tools, a kind of specialized probe capable of unearthing in the haystack of these highly altered lactic aggregates the genetic code of tiny needles (bacteria, archaea, yeasts, etc.).
You have 57.09% of this article left to read. The rest is reserved for subscribers.
