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The teeth of people buried 700 years ago point to the origin of the Black Death, the greatest pandemic in history

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Amid the archeology fever, Russian adventurers unearthed two medieval cemeteries near Lake Issyk-Kul (Kyrgyzstan, Central Asia) in the late 19th century. The Silk Road ran through the region and it revealed what was in the tombs: small hoards of coins and ornaments from the most remote corners of Eurasia. The excavators found that there were too many tombstones for the years 1338 and 1339. The mystery has remained to this day. A collaborative work by historians, archaeologists, and geneticists, published in Nature has analyzed the teeth of several burials and found DNA Yersinia pestisthe bacterium that caused the greatest pandemic in history, the black plague that ravaged Europe and Asia a decade later.

One of the tombstones translates as: “In 1649 [que corresponde a 1338 en el calendario occidental], and is the year of the tiger. Bars, in Turkish. This is the tomb of the Sanmaq believer. [Él] died of the plague.” That last word turned historians of the time on their head. Pestilence might refer to the plague, but the pandemic, which killed between 50 and 200 million people, did not break out until 1347, with the first plague cases in the Black Sea ports, Constantinople, Marseille or Barcelona Almost everything is known about the Black Death: what bacteria caused it, how the fleas from infected rats transmitted it to humans, that genetics say that this strain is responsible for the outbreaks that have occurred over the past 500 years and that it came from somewhere in Central Asia, but its exact location has been the subject of much debate among historians.

German, British and Russian scientists have received permission from the authorities to remove 50 milligrams of enamel and dentin from the teeth of 30 deceased buried in the Peter the Great Museum of Anthropology and Ethnography of the Russian Academy of Sciences (Kuntskámera, St .Petersburg). They managed to extract DNA from seven of them. His analysis shows that they were locals. But the important thing came later. Foreign genetic material was found in three of the deceased. His analysis left no doubt: it was DNA from a strain of the bacterium Y. pestis and not just any.

“[Esta cepa] It is the ancestor of 80% of all tribes currently in circulation, including the Black Death and all tribes after it.

Johannes Krause, Director of the Max Planck Institute for Evolutionary Anthropology

Johannes Krause, Director of the Max Planck Institute for Evolutionary Anthropology (Germany) and lead author of the in Nature, is clear: “It is the predecessor of 80% of all strains currently in circulation, including the Black Death and all subsequent strains.” To support their claim, Krause and his colleagues constructed the family tree of the Y. pestis with the genome of 250 specimens, 47 of them from the past. They observed a star-shaped explosion and diversification of strains of the bacterium around the mid-14th century and found that the strain detected in the dead from the Chu Valley, where Issyk-Kul Lake is located, on beginning of everything.

Maria Spirou, a researcher at the University of Tübingen and lead author of the study, explains in a note: “We discovered that ancient tribes from Kyrgyzstan are right at the nexus of this massive diversification event. In other words, we’ve found the origin tribe of the Black Death and even know its exact date. [es decir, el año 1338]“. Russian archaeologists have already indicated that something happened this year. While in the previous decade the number of those buried in the two cemeteries Kara-Djigach and Burana did not exceed twenty in the worst years, the number doubled to 1338 and reached one hundred in the following year. The circle closes.

All evidence points to the first documented cases of the Black Death occurring in 1347 in the port cities of present-day Turkey. In the following months there were outbreaks in other ports further and further west: Athens, Naples, Marseille or Barcelona, ​​​​as early as the spring of 1348. Two years were enough to reach the Nordic countries. It also punishes North Africa, the Arab countries, India and China. But everything had to start in or near the Chu Valley, at the foot of the Heavenly Mountains (Tian Shan, the border region between modern-day Kazakhstan, Kyrgyzstan and the People’s Republic of China).

“Both cemeteries were located in the heart of the Silk Road trade network, right next to the causeway”

Philip Slavin, historian at the University of Stirling (UK)

The historian at the University of Stirling (UK) and co-author of the study, Philip Slavin, highlights how trade routes were a key element in the spread of the plague and the role this part of the world played in its early days. “Both cemeteries were at the heart of the Silk Road trade network, right next to the dam,” he says in an email.

However, other historians do not share the conclusions of this research. One of the skeptics is not just anyone. Ole J. Benedictow is Professor Emeritus at the Department of Archaeology, Conservation and History at the University of Oslo (Norway). In 2004 he wrote his best-known book, The Black Death 1346-1353: The Complete Story (second edition updated last year). The central thesis of the work is recalled in an e-mail: “There is considerable historical evidence that the Black Death originally erupted in the lower Volga area, most likely in the delta, where there is an active plague reservoir with a large accumulation of data. , historically and that still causes plague epidemics. In other words, for this historian everything began in this area of ​​​​Russia washed by the Caspian Sea, very far from the Chu Valley.

At the time of the Black Death outbreak, the plague pathogen was widespread among rodents in the territory occupied by the Golden Horde Khanate (one of the successor states of the Mongol Empire). As Benedictow recalls, this stretched “from the western border of China to the eastern border of present-day Romania. For the Norwegian historian, who hypothesizes that the genetic structure of the plague in the local part of the reservoir may be similar to that of the lower Volga Delta reservoir, the two cemeteries that are the focus of this new research cannot be at the beginning of the pandemic: “Issyk -Kul is located in a fairly remote settlement in a vast area that contains a reservoir for wild rodent infestations. Such an area will continue to experience plague epidemics when people come into contact with sick rodents that contract the disease. This must also have been the case for the population in Issyk-Kul. Whether there was any contact between Issyk-Kul and the Lower Volga is unknown, but I doubt it.”

Benedictow recognizes that exploring ancient DNA can make important contributions to the history of the disease. “It is valuable to have some basic knowledge about the origin and development of the pathogen.” But it also gives a very elegant warning of excesses. “I hope that the people reading this excellent article [por la investigación de Nature] also recognize that the genetic history of the plague itself is of limited interest and significance.” To him, “plague epidemics and Black Death epidemics are important because of their impact on historical society.” He concludes, “Um becoming critical, the Black Death and historical plague epidemics depended on human actions and the efficiency of propagation in human society that human culture and technology would produce.”

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