Mystery of Black Death’s origin solved after 675 years, researchers say

A deadly pandemic with mysterious origins: It may sound like a modern headline, but scientists have debated for centuries the source of the Black Death that ravaged the medieval world.

Not anymore, according to researchers who say they identified the source of the plague in a region of Kyrgyzstan, after analyzing DNA from remains at an ancient cemetery.

“We’ve managed to stop all those age-old controversies about the origin of the Black Death,” said Philip Slavin, a historian and part of the team whose work was published Wednesday in the journal Nature.

The Black Death was the first wave of a nearly 500-year-long pandemic. In just eight years, from 1346 to 1353, it is estimated to have killed up to 60% of the population of Europe, the Middle East and Africa.

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 work describing an ancient burial ground in what is now northern Kyrgyzstan.

It reported a spike in burials in 1338-1339 and that several headstones described people who “died of the plague”.

“If you have one or two years of 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,” he said.

It was a clue, but nothing more without determining what killed the people on the site.

For this, Slavin worked together with specialists who research ancient DNA.

They extracted DNA from the teeth of seven people buried at the site, explains Maria Spyrou, a researcher at the University of Tübingen and author of the study.

Because teeth contain many blood vessels, they give researchers “high chances of detecting blood-borne pathogens that may have caused the deaths of the individuals,” Spyrou told AFP.

Once extracted and sequenced, the DNA was compared to a database of thousands of microbial genomes.

“One of the hits we were able to get… was a hit for Yersinia pestis,” better known as the 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 old individual was carrying at the time of their death.”

The onset of the Black Death has been linked to a so-called “Big Bang” event, when existing strains of plague, carried by fleas on rodents, suddenly diversified.

Scientists thought it might have happened as early as the 10th century, but hadn’t been able to pinpoint a date.

The research team painstakingly reconstructed the Y. pestis genome from their samples and found the strain in the pre-diversification cemetery.

And rodents now living in the region were also found to carry the same ancient species, leading the team to conclude that the “Big Bang” must have happened somewhere in the area in a short window before the Black Death.

The Excavation of the Black Death Cemetery at the Royal Mint Site
A 2009 archival photograph of the Black Death burial trench during excavations between the concrete foundations of the Royal Mint, East Smithfield, London.

Getty Images

The study has some unavoidable limitations, including a small sample size, according to Michael Knapp, an associate professor at New Zealand University of Otago who was not involved in the study.

“Data from many more individuals, times 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 praised the research as “really valuable” nonetheless.

Sally Wasef, a paleogenetician at the Queensland University of Technology, said the work offered hope for unraveling other ancient scientific mysteries.

“The study has shown how robust microbial ancient DNA repair can help uncover evidence to resolve longstanding debates,” she told AFP.

According to the World Health Organization, a total of 3,248 cases were reported between 2010 and 2015, resulting in 584 deaths. The Democratic Republic of Congo, Madagascar and Peru were the worst affected countries.

The plague was first introduced to the US in 1900 from steamships carrying infected rats. The last urban outbreak of rat-related plague in the US occurred in Los Angeles between 1924 and 1925.

According to the U.S. Centers for Disease Control and Prevention, people usually get bubonic or septicemic plague after being bitten by a flea that carries the bacteria. Humans can also contract the disease when handling an infected animal.

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