Where did the black death disease start? DNA detectives find important clues.

When and where did the black death occur? This question has been asked for centuries and has sparked intense debate among historians.

Currently, a group of researchers report that the answer was found in the pulp of people buried in the 14th century.

Based on an analysis of conserved genetic material, researchers report that Black Death arrived in 1338 or 1339 near Issyk Kul Lake in what is now the mountainous region of western China in Kyrgyzstan. .. Eight years before the devastation of the Eurasian continent, the plague first infected people in a nearby small merchant settlement, killing 60 percent of its victims.

The study was led by Wolfgang Haak and Johannes Krause of the Max Planck Institute for Evolutionary Anthropology and Anthropology in Germany, and Philip Slavin of the University of Stirling in Scotland. Explained their findings on Wednesday in nature..

Known as plague, named after the black spots that appear on the victim’s body, it is caused by Yersinia pestis, a bacterium carried by rodent fleas. The disease is still present today and is carried by rodents on all continents except Australia. However, due to good hygiene, infection is rare. Infections can be easily cured with antibiotics.

Mary Fissell, a medical historian at Johns Hopkins University, said that the plague of the 14th century was actually the second largest plague of Y. pestis, first the plague of the 6th century. However, black death is the most well-known and is considered one of the most deadly epidemics in human history.

The horror was recorded by Giovanni Boccaccio, an Italian writer and poet who survived the plague when it struck Florence. illness, He wrote“Swelling of the groin or armpit showed the first signs in both men and women. Some grew to the size of a normal apple, others to the size of an egg, and people bubo them. “,” Became known as “a sign of imminent death.”

Historians have followed a fashion path — apparently starting near China or the western border of China and traveling along trade routes to Europe, North Africa and the Middle East.

But Monica H. Green, Medical history and independent scholars Those who were not involved in the new paper said historians would not be able to answer the questions they posed: was it really Yersinia pestis that caused this pandemic?

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

She vividly remembers meeting a paleopathologist who was studying leprosy 20 years ago. Leprosy leaves a visible mark on the skeleton.

“When do you plague?” Dr. Green asked. She said paleopathologists replied that the disease that kills people very quickly leaves no trace on the bones, so plague cannot be studied.

Now that deadlock has been overcome.

The quest for the origin of the plague is “like a detective story,” said Dr. Fissell, who was not involved in the new study. “Now they have really good evidence of the crime scene.”

Hunting dates back more than a decade, to the time when the group that led the latest research surprised archaeologists. Their report They were able to find Yersinia pestis DNA in the skeletal teeth.

The study involved plague victims in London.

The citizens of London in the 14th century knew that the plague was coming, so they consecrated the cemetery in advance to prepare for the victims.The body was excavated and is now Museum of London.. The situation was ideal, as these victims not only came from the plague graveyard, but also knew the date of their death.

“As an epidemiological case study, it’s perfect,” said Dr. Green.

“The technical skills involved in this job were amazing,” she added.

Since the study in London, the group has analyzed genetic material from plague victims elsewhere and constructed a DNA pedigree of plague bacterial variants. Other researchers reported that the tree had a trunk, and then at once its offspring appeared to have exploded into four branches of the plague strain found in rodents today. They called the event the Big Bang and began a quest to find out when and where it happened.

Historians have proposed various dates from the 10th century to the 14th century.

Dr. Slavin, a latecomer to the group that analyzed plague victims in Kyrgyzstan, said one of his dreams was to solve the mystery of the origin of plague.

“I knew two Christian cemeteries in Kyrgyzstan and started digging,” he said.

Surprisingly, he noticed that hundreds of tombstones were accurately dated. Some had an inscription in the old language, Syriac, saying that they died of a “plague.” And in the year they died, the mortality rate of the population soared.

“It wasn’t just a year, so it caught my attention,” said Dr. Slavin. It was 1338, “only seven or eight years before the plague came to Europe.”

“We can’t ask for more than having a tombstone that year,” he said.

Researchers have found plague DNA in the teeth of three individuals who said the tombstone had died from a “plague.”

The group also reports that the rodents that spread the bacteria to those victims were marmots. Today, marmots in the area have fleas that carry a type of Yersinia pestis that appears to be of direct origin in their ancestral lineage.

And researchers report that the Kyrgyzstan strain is from a stem that has exploded into four strains. It is the beginning of the Big Bang and the group proposes.

If they are correct, the Big Bang seems to have happened just before the Eurasian plague, and the plague epidemic was through trade routes, not through first-century military operations, as some historians suggest. It shows that just a while ago.

Dr. Green and other historians said the big bang happened Mongolians in the early 13th century Spread the bacteria. But if so, the Kyrgyzstan bacteria would have come from one of the branches, not from an ancestral strain.

“These battles of the 1200s are completely irrelevant,” Dr. Fissell said.

Dr. Green said he was confident that the group had found plague victims in Kyrgyzstan. But she said the evidence currently available is insufficient to justify that bold claim.

“Look forward,” Dr. Fissell said, adding that he hopes more evidence may emerge.

So far, she said the detective work has found important clues.

She added that the work “places pins on the map with the date”.