The origin of the “black death” is a very old debate among historians. One of the tracks often put forward was that of China, but no robust evidence could support this theory. The Black Death epidemic reached Europe in 1346 through the Mediterranean basin, via ships carrying goods from the Black Sea. In eight years, the “black death” killed up to 60% of the population of Europe, Middle East and North Africa.
It was thanks to ancient human DNA that the researchers were able to trace the source. They based themselves on two medieval burial sites in northern Kyrgyzstan. Near Lake Issyk Kul, a hundred tombs, dated 1338-1339, bore an epitaph mentioning a “death of pestilence”, in Old Syriac. An index of excess mortality, long before the Black Death hit Europe.
Dental DNA from seven skeletons showed they had been infected with the bacteria Yersinia pestis responsible for the Black Death. It was also a strain at the base of the plague “genetic tree”, right at the crux of the massive genetic diversification associated with the epidemic in Europe. This confirms, according to the researchers, that this region of the Tian Shan was the starting point of the expansion. The study also establishes that the living rodents of the Tian Shan harbor a bacterial strain closest ever found to that of the human victims of 1338-1339. At the time, local people practiced long-distance trade and lived in the heart of the Silk Roads. Their numerous voyages must have allowed the spread of the epidemic via the Black Sea. Every year, thousands of people are still infected with the plague. In the Tian Shan Mountains, marmots are the main animal reservoir of the disease.