The Black Death: a clue to where the plague originated

Where and when did the Black Death originate? This question has been asked for centuries and has led to heated debate among historians.

Now, a team of researchers reports that they have found the answer in the pulps of people buried in the 14th century.

Based on their analysis of preserved genetic material, the researchers report that the Black Death came in 1338 or 1339 near Issyk-Kul, a lake in the mountainous region of western China, where present day Kyrgyzstan. The bubonic plague first infected people in a small, nearby settlement of merchants eight years ago when it ravaged Eurasia, killing 60% of the population.

The investigation was led by Wolfgang Haak and Johannes Krause of the Max Planck Institute for Evolutionary Anthropology and the Science of Human History in Germany as well as Philip Slavin of the University of Stirling in Scotland, who described their findings Wednesday in the journal Nature.

The so-called Black Death – named for the dark spots that appear on the victim’s body – is caused by a bacterium Yersinia pestis, carried by fleas that live on rodents. The disease is still present today, carried by rodents on every continent except Australia. But infections are rare because of better hygiene. Infections are easily cured with antibiotics.

Mary Fissell, a medical historian at Johns Hopkins University, says the 14th-century plague was actually the second-largest epidemic of Y. pestis – the first being the Justinian plague in the sixth century. But the Black Death is best known and considered one of the deadliest epidemics in human history.

Its horrors were recorded by Giovanni Boccaccio, an Italian writer and poet who had lived through the plague when it hit Florence. Diseases, I wrote“The first signs of it are the same in men and women as swellings in the groin or under the armpits, some growing to the size of a normal apple and others the size of an egg. , and people call them blisters. , “so-called” sign of impending death. ”

Historians have traced the epidemic’s path – it seems to have started in China or near China’s western border and moved along trade routes to Europe, North Africa and the Middle East.

But Monica H. Green, an independent medical historian and scholar who was not involved in the new paper, noted that historians will never be able to answer the question they posed: Did Yersinia pestis really cause this great pandemic?

“We hit a wall. We are historians and we deal with documents,” said Dr. Green.

She vividly remembers meeting a paleontologist 20 years ago who had studied leprosy, which left visible marks on skeletons.

“When will you do the plague?” Dr. Green asked. She said the paleontologist replied that they couldn’t study bubonic plague because a disease kills so quickly that it doesn’t leave any marks on the bones.

Now, that deadlock has been overcome.

Dr Fissell, who was not involved in the new study, said finding the source of the plague “was like a detective story. “Now they have really good evidence on the crime scene.”

The hunt goes back more than a decade, when the team leading the latest study stunned archaeologists with their report that they could find the DNA of the plague bacteria in the teeth of the skeletons.

That study involved plague victims in London.

Fourteenth-century Londoners knew the Black Death was coming, so they built a graveyard in advance to prepare its victims. The bodies have been exhumed and are now kept in Museum of London. The situation was ideal because these victims not only came from a plague graveyard, but their date of death was known in advance.

“As an epidemiological case study, it is perfect,” says Dr. Green.

“The technical skill that has been put into this job is amazing,” she added.

Since the London study, the team has analyzed genetic material from plague victims in other locations, building a DNA genealogy of plague bacterial variants. It and other researchers reported that the plant had a single stem and then, all at once, seemed to explode into four branches of strains of Y. pestis whose descendants are now found in rodents nibble. They called the event the Big Bang and began looking for when and where it happened.

Historians suggest various dates ranging from the 10th to the 14th centuries.

Dr Slavin, who came after the team that analyzed plague victims in Kyrgyzstan, said one of his dreams was to solve the puzzle about the origins of the Black Death.

“I became aware of two Christian cemeteries in Kyrgyzstan and started doing research,” he says.

To his surprise, he discovered that hundreds of gravestones had been precisely dated. Some have inscriptions that say, in an ancient language, Syriac, that the person died of a “plague.” And the death rate of the population spiked the year those people died.

“That caught my attention because it doesn’t happen every year,” says Dr. Slavin. It was 1338, “just seven or eight years before the Black Death reached Europe.”

“We couldn’t ask for more than to have tombstones with the same year,” he said.

Researchers found plague DNA in the teeth of three people whose tombstones said they had died of the “plague.”

The team also reports that the rodents that transmit the bacteria to their victims are bugs. Marmots in that area today have fleas carrying a strain of Y. pestis that seems to have descended directly from the ancestral strain.

And the researchers report that the strain in Kyrgyzstan was from a stem that exploded into four strains. That was the beginning of Big Bang, the group suggested.

If they are correct, Dr. Fissell said, it seems likely that the Big Bang occurred just before the Black Death in Eurasia, suggesting that the spread of the plague was most likely through trade routes rather than as Some historians have proposed, through military action for a century. earlier.

Dr. Green and other historians have suggested that the Big Bang occurred when Mongols in the early 13th century bacteria spread. But if it were, the bacteria in Kyrgyzstan would be from one of the clade, not the ancestral line.

“The battles of the 1200s were quite unrelated,” Dr. Fissell said.

Dr. Green said she was confident the team had found victims of the plague in Kyrgyzstan. But she says the existing evidence is not enough to justify its bold claims.

“Stay tuned,” Dr. Green said, adding that she hopes more evidence may emerge.

For now, she said, detective work has found important clues.

The work, she added, is “pinned to the map, dated.”

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