DNA analysis revealed the origins of the Black Death

(CNN) – Tombstones in what is now Kyrgyzstan have revealed promising details about the origins of the Black Plague, the world’s most devastating plague outbreak estimated to have wiped out half of Europe’s population within seven years during the Middle Ages.

Historians have debated the origin of this epidemic for centuries, but inscribed tombstones, some of which indicated a mysterious epidemic, and genetic material from bodies exhumed from two 13th-century graves provided some answers. Especially this old question.

Researchers first dug into burials in the 1880s, and grave inscriptions written in Syriac were thoroughly re-examined in 2017 by historian Phil Slavin, associate professor at the University of Stirling, Scotland. He realized that of the 467 accurately dated burials, a disproportionate number, 118, occurred in just two years: 1338 and 1339. He revealed his description as “amazing.”

Shown is a view of the Tian Shan Mountains in Kyrgyzstan, where scholars have identified the origins of the plague outbreak that caused the Black Death in the Middle Ages.

“When you have a year or two with increased mortality, it means that something was going on. But the other thing that really surprised me was the fact that it wasn’t just a year, because it was only seven or eight years ago (the plague),” Slavin said in a statement. Journalist.

The origins of the black plague

The inscriptions on the tombstones indicate a mysterious epidemic.

He added, “I have always been fascinated by the Black Death. One of my dreams was to be able to solve this mystery from its origins.”

Slavin and his collaborators discovered that the remains of 30 people buried in Kyrgyz cemeteries had been transferred to the Peter the Great Museum of Anthropology and Ethnography in Saint Petersburg, Russia. The research team got permission to try extracting DNA from the skeletons to understand how they died.

From seven individuals, the researchers were able to extract and sequence DNA from their teeth. In this genetic material, they found DNA from the plague bacterium, which scientists call Yersinia pestis, in three of the individuals, who died in 1338, inscribed on their tombstones.

This confirms that the plague mentioned on the tombstones was indeed the “Black Death”, which is transmitted from rodents to humans via fleas.

In 1347, the plague first entered the Mediterranean through merchant ships carrying goods from the Black Sea regions. The disease then spread across Europe, the Middle East and North Africa, evoking up to 60% of the population, according to the study published Wednesday in the journal Nature.

Some historians believe that the strain that caused the Black Death originated in China, while others believe that it originated near the Caspian Sea. India was also raised as a possible asset. The plague strain continued to spread around the world for 500 years.

The original excavations appear at the Kara-Djigach cemetery, near Lake Issyk Kul in Kyrgyzstan.

The evolution of the plague dynasty

The latest study adds to the wealth of information revealed by sequencing ancient pathogens such as the plague that leave a genetic imprint on human DNA.

In 2011, scientists first sequenced the genome of the plague bacterium Yersina pestis found in two plague victims buried in a London cemetery. Since then, more genetic material has been recovered from cemeteries across Europe and southern Russia.

This work showed an explosion in the diversity of plague strains, the “big bang” that occurred in the evolution of plague bacteria sometime before the Black Death swept through Europe, likely in the 10th and 14th centuries.

Researchers involved in this latest study believe that the area around the two tombs near Lake Issyk Kul in Kyrgyzstan must have been the origin of the plague strain that caused the Black Death, since the ancient plague genome that the team reconstructed from teeth revealed one strain of plague that is the most recent direct ancestor of an event “the big explosion”. This places it at the beginning of the Black Plague outbreak and before it reaches Europe.

“We found that the ancient dynasties from Kyrgyzstan lie exactly at the junction of this mega diversification event,” said lead study author Maria Spiro, a postdoctoral researcher at the University of Tübingen in Germany.

Other evidence supporting the study researchers’ claim comes from comparing plague strains found in modern rodents with those they sequenced from cemeteries. They found that the modern plague strains most closely related to the ancient one are today found in wild rodents, such as badgers, that live in the Tian Shan Mountains near the two burial sites.

plague

The tomb of this tomb was written in the Syriac language and reads: “This is the tomb of the believer Sanmak. [Murió de peste]”.

“What is really remarkable is that today, in the rodents that live in that region, we have the closest living relative of the Big Bang strain (of the plague bacteria),” said study senior author Johannes Krause, director of the Max Planck Institute for Evolutionary Anthropology. in Leipzig, Germany.

“Not only did we find the ancestor of the Black Death, but we also found the ancestor of most of the plague strains prevalent in the world today.”

There are still many things the team doesn’t know, like exactly which animal transmitted the disease to humans. But Krause said understanding the origin of the largest pandemic in human history could help prepare for future outbreaks.

“Like Covid, the Black Death was an emerging disease, the beginning of a massive pandemic that lasted for nearly 500 years. It is very important to understand under what circumstances it emerged,” Krause said.

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