We finally know where the black plague came from

The Black Death pandemic, which decimated a large portion of Europe’s population in the Middle Ages, emerged in Central Asia, in what is now Kyrgyzstan, according to a study that has been questioned for nearly seven centuries.

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Researchers have been able to trace the source thanks to ancient human DNA extracted from a 14th-century burial site in northern Kyrgyzstan. Their findings, published Wednesday in the journal Nature, end a very old debate among historians.

The Black Death epidemic reached Europe in 1346 via the Mediterranean basin with ships transporting goods from the Black Sea. In just eight years, the “Black Death” killed up to 60% of the population in Europe, the Middle East and North Africa. And marked the beginning of a long wave of the epidemic that would resurface intermittently for 500 years.

Where was she born ? One of the most advanced clues was that of China, but no solid evidence could support this theory.

“The Black Death has always fascinated me, and one of my dreams has been to unravel the mystery of its origins,” disaster historian Phil Slavin, one of the study’s authors, said during a news conference.

“Death of the Plague”

This professor at the University of Stirling (Scotland) knew of two medieval burial sites near Lake Issyk Kul in Kyrgyzstan that had been excavated in the late 19th century.

Out of more than 400 tombstones, 100 were precisely dated: 1338-1339. With an epitaph mentioning an elliptical “death of the plague” in Old Syriac. So many signs of abnormal excess mortality within a community seven or eight years before the Black Death struck Europe.

To find the cause of death, the researchers searched the dental DNA of seven skeletons. “The dental pulp is a valuable source because it is a highly vascularized area that offers a high chance of detecting pathogens in the blood,” Maria Spyrou, from the University of Tübingen in Germany, told AFP, also an author of the study.

The DNA could be sequenced – delicate work since it was fragmented – and then compared to a database containing the genomes of thousands of bacteria.

Verdict: The bodies were infected with the bacterium Yersinia pestis, the bacillus responsible for black plague and transmitted to humans from rodent fleas. This community was thus the victim of the same scourge that afflicted Europe a few years later.

Analyzes of the genome of Yersinia pestis also revealed that it is an ancestral strain of the bacterium. The one who stands at the base of the “genetic tree” of the plague.

Scientists rightly associate the occurrence of the Black Death in Europe with a genetic “Big Bang” in which the parent bacteria massively diversified.

In the heart of the Silk Roads

The tribes discovered in Kyrgyzstan are precisely “the core of that massive diversification” that took place around 1330. This confirms that this region of the world, the Tian Shan, was indeed the starting point of expansion, according to Maria Spyrou.

In addition, in rodents living in the Tian Shan today, the researchers identified a strain of the bacterium very similar to that found in human victims from 1338-1339, “the closest found in the world,” Johannes Krause added to the Max Planck Institute, co-author of the study.

These were Christian communities, ethnically diversified (Mongolians, Uyghurs…) who, according to the burial objects found, practiced a long-standing trade: pearls from the Pacific, corals from the Mediterranean, silk dresses… “Living in the heart of the Silk Roads they had a lot travel, which played a role in the spread of the epidemic across the Black Sea,” says Phil Slavin.

The plague has never been eradicated from the face of the earth: thousands of people continue to become infected every year, especially in Central Asia. In the Tian Shan Mountains, marmots are the main animal reservoir of the disease.

Fortunately, there is no need to fear a deadly pandemic like in the Middle Ages: not because the bacterium is less virulent, but because hygiene conditions and the use of antibiotics no longer have anything to do with the past.

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