Ancient DNA solves the mystery of the origin of the Black Death in the Middle Ages

By Will Dunham

(Reuters) – The ancient DNA of bubonic plague victims buried in cemeteries along the Old Silk Road trade route in Central Asia has helped unravel the mystery by pointing the region north of Kyrgyzstan to the beginning of a brutal death that killed tens of millions of people. People in the middle of the 14th century.

On Wednesday, scientists said they found ancient DNA traces of the Yersinia pestis plague bacterium in the teeth of three women buried in a medieval Nestorian Christian community in the Chui Valley near Lake Issyk-Kul at the foot of the Tien Shan Mountains in 1338-1339. . The first recorded deaths in other parts of the pandemic occurred in 1346.

Reconstruction of the pathogen’s genome has shown that this strain has produced not only the Black Death that devastated Europe, Asia, the Middle East and North Africa, but also many modern plague strains.

“Our conclusion that black death originated in Central Asia in the 1330s has put an end to centuries of controversy,” said Philip Slavin, a historian at the University of Stirling in Scotland and co-author of a study published in the journal Nature.

The Silk Road was a land route for caravans from China through the beautiful cities of Central Asia to the Byzantine capital Constantinople and Persia. If the pathogen rode in caravans, it may have served as a lethal agent.

“There are a number of hypotheses that a pandemic could occur, especially in East Asia, China, Central Asia, India, or near the site of the first epidemics in the Black Sea and Caspian Sea in 1346. Maria Spiru, an archaeologist and co-author of the study at the University of Tübingen in Germany, said.

“We know that trade at the beginning of the Black Death determined the spread of the plague in Europe. It is reasonable to assume that such processes determined the spread of the disease from Central Asia to the Black Sea since 1338. 1346,” added Spiru.

The origins of the pandemic are hotly debated, as evidenced by the current controversy over the emergence of the COVID-19 pandemic.

Black death was the deadliest pandemic in history. It could kill between 50% and 60% of the population in parts of Western Europe and 50% in the Middle East, leading to an estimated 50-60 million deaths, Slavin said. Slavin added that “countless numbers” of people had died in the Caucasus, Iran and Central Asia.

“In the Middle Ages, we saw high mobility and rapid spread of human pathogens,” said Johannes Krause, an archaeologist and co-author of the study, director of the Max Planck Institute for the Study of Human History in Germany. “We should not underestimate the possibility that pathogens can spread from very remote places around the world, probably due to a zoonotic event” – an infectious disease transmitted from animals to humans.

Researchers analyzed the teeth of seven people buried in the cemeteries of the Burana and Kara-Djigach communities, a rich source of DNA, and obtained plague DNA from three people in Kara-Djigach.

Among the graves excavated in the 19th century, stones were placed on the heads of those who died of the Syrian “infectious disease.” Items such as pearls, coins, and clothing from distant lands indicate that the cities were engaged in international trade, perhaps by staying in distant caravans and offering leisure services.

Bubonic plague, which was untreatable at the time but can now be treated with antibiotics, caused swollen lymph nodes, blood and pus, and the infection spread to the blood and lungs.

In Europe, the disease is mainly transmitted by flea bites on infected rats. The pandemic is caused by wild rodents, probably marmots, a type of taiga, Slavin said. Rodent caravan mechanisms may have contributed to its spread, but other infections may include human fleas and lice.

“We found that the closest relatives of that Y. pestis strain that caused Black Death are still present in marmots in this region,” Krause said.

(Will Dunham’s Washington Speech, edited by Rosalba O’Brien)

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