TOKYO, June 15, 2022 (BSS/AFP) - A deadly pandemic with mysterious origins: 
it might 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 pinpointed the source 
of the plague to a region of Kyrgyzstan, after analysing DNA from remains at 
an ancient burial site.

"We managed to actually put to rest all those centuries-old controversies 
about the origins 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 initial wave of a nearly 500-year pandemic. In just 
eight years, from 1346 to 1353, it killed up to 60 percent 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 with the Black Death", found an intriguing clue 
in an 1890 work describing an ancient burial site in what is now northern 
Kyrgyzstan.

It reported a spike in burials in 1338-39 and that several tombstones 
described people having "died of pestilence".

"When you have one or two years with excess mortality it means that something 
funny was going on there," Slavin told reporters.

"But it wasn't just any year -- 1338 and 1339 was just seven or eight years 
before the Black Death."

It was a lead, but nothing more without determining what killed the people at 
the site.

For that, Slavin 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 "high chances 
of detecting blood-borne pathogens that may have caused the deaths of the 
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 that we were able to get... was a hit for Yersinia pestis," 
more commonly known as plague, said Spyrou.

The DNA also displayed "characteristic damage patterns," she added, showing 
that "what we were dealing with was an infection that the ancient individual 
carried at the time of their death."

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

Scientists thought it might have happened as early as the 10th century but 
had not been able to pinpoint a date.

The research team painstakingly reconstructed the Y. pestis genome from their 
samples and found the strain at the burial site pre-dated the 
diversification.

And rodents living in the region now were also found to be carrying the same 
ancient strain, helping the team conclude the "Big Bang" must have happened 
somewhere in the area in a short window before the Black Death.

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

"Data from far more individuals, times and regions... would really help 
clarify what the data presented here really means," said Knapp.

But he acknowledged it could be difficult to find additional samples, and 
praised the research as nonetheless "really valuable".

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

"The study has shown how robust microbial ancient DNA recovery could help 
reveal evidence to solve long-lasting debates," she told AFP.