The mystery of the origin of the Black Death solved 675 years later
After nearly 700 years, scientists have solved the mystery of a deadly plague that wiped out millions of people.
A deadly pandemic with mysterious origins – it may sound like a modern headline, but scientists have spent centuries debating the source of the Black Death that devastated the medieval world.
Not anymore, according to researchers who say they have identified the source of the plague in a region of Kyrgyzstan, after analyzing DNA from remains at an ancient burial site.
“We have succeeded in putting an end to all these age-old controversies about the origins of the Black Death,” said Philip Slavin, historian and member of the team whose work was published in the journal on Wednesday. Nature.
The Black Death was the first wave of a nearly 500-year-old pandemic. In just eight years, from 1346 to 1353, it killed up to 60% of the population of Europe, the Middle East and Africa, according to estimates.
Slavin, an associate professor at the University of Stirling in Scotland who has ‘always been fascinated by the Black Death’, found an intriguing clue in an 1890 book describing an ancient burial site in what is now northern Kyrgyzstan .
He reports a peak in burials in 1338-1339 and that several tombstones depicted people “died of the plague”.
“When you have one or two years with excess mortality, it means something funny was going on there,” Slavin told reporters.
“But it wasn’t just any year – 1338 and 1339 were just seven or eight years before the Black Death.”
It was a lead, but nothing more without determining what killed the people on the site.
For this, Slavin has teamed up with specialists who examine ancient DNA. They extracted DNA from the teeth of seven people buried at the site, explained Maria Spyrou, a researcher at the University of Tuebingen and author of the study.
Because teeth contain many blood vessels, they give researchers “a high chance of detecting blood-borne pathogens that may have caused the death of individuals,” Spyrou told AFP.
“Big Bang” event
Once extracted and sequenced, the DNA was compared against a database of thousands of microbial genomes.
“One of the hits we were able to get…was a hit for Yersinia pestis,” more commonly known as plague, Spyrou said.
The DNA also showed “characteristic patterns of damage”, she added, showing that “what we were dealing with was an infection that the former individual was carrying at the time of death”.
The start of the Black Death has been linked to a so-called “Big Bang” event, when existing strains of the plague, which are carried by fleas on rodents, suddenly diversified.
Scientists thought it might have happened as early as the 10th century but were unable to pinpoint a specific date.
The research team painstakingly reconstructed the Y. pestis genome from their samples and found that the strain at the landfill predated diversification.
And rodents living in the area were also found to carry the same ancient strain, helping the team conclude that the “Big Bang” must have occurred somewhere in the region within a short window before the Black Death.
According to Michael Knapp, an associate professor at the University of Otago in New Zealand who was not involved in the study, the research has unavoidable limitations, including a small sample size.
“Data from many more individuals, time periods and regions… would really help clarify what the data presented here really means,” Knapp said.
But he acknowledged it could be difficult to find additional samples and hailed the research as nevertheless “really valuable”.
Sally Wasef, a paleogeneticist at Queensland University of Technology, said the work offered hope of unraveling other ancient scientific mysteries.
“The study showed how robust recovery of ancient microbial DNA could help uncover evidence to resolve long-running debates,” she told AFP.