As the world continues to wrestle with the COVID-19 pandemic, scientists believe they’ve solved the 700-year-old mystery of the world’s deadliest pandemic: Black Death.
The journal Nature this month published new research that says biological evidence suggests Black Death originated in Central Asia in a location now known as Kyrgyzstan. And they believe it’s the granddaddy of the plagues that have followed.
The paper’s co-author, Phil Slavin, who is a historian at the University of Stirling in Scotland, told NPR that the region “gave rise to the majority of (modern plague) strains circulating in the world today.”
“Our study puts to rest one of the biggest and most fascinating questions in history and determines when and where the single most notorious and infamous killer of humans began,” Slavin said in a news release on the study.
Black Death was the first wave of a plague that lasted close to 500 years and killed roughly 50 million people in Europe and the Mediterranean. During a wave in the 1300s, researchers believe it killed up to 60% of the western Eurasian population. But no one knew where or how it began.
The study was written by an international team that includes researchers from Germany, Italy, Russia, Scotland and Kazakhstan.
Black Death was an ugly death. According to NPR, “Black Death … got its frightening name because those infected developed gangrenous, blackened lesions all over their body. The disease is characterized by fever and swelling of the lymph nodes and caused by the bacterium Yersinia pestis, which spreads via rodents carrying infected fleas.”
They note that the Black Death “had a profound demographic and socioeconomic impact in all affected areas, with the European historical record being the most extensively studied resource until now.”
Grave evidence emerges
The researchers believe that one strain of plague mutated into four different lines and the Black Death evolved from there. They suspect it came from the Kyrgyzstan area because two cemeteries there had “an unusually high number of tombstones” dated 1338-1339, which was eight years before the Black Death reached Europe.
Those tombstones referred to “pestilence” as the cause of death, which suggested the people buried there died in a pandemic.
Science Alert said that roughy 30 skeletons had been taken from graves in the two cemeteries, located in the Chüy Valley in northern Kyrgyzstan in the late 1800s during excavations. The bodies were stored in Russia.
The paper’s lead author, Maria Spyrou, a geneticist at the University of Tubingen in Germany, and colleagues used their expertise in ancient DNA to examine tooth samples from some of those bodies. They said they believed teeth would provide the greatest likelihood of finding DNA that could be studied, since the bodies were largely decayed. And they did find Y. pestis in teeth from three of the bodies and confirmed that they died from plague.
Then they looked to see how closely that strain matched the Black Death and other plagues that came later, creating an “evolutionary tree” that showed subsequent plagues likely originated in that geographic area.
“Our synthesis of archaeological, historical and ancient genomic data shows a clear involvement of the plague bacterium Yersinia pestis in this epidemic event,” the researchers wrote in the study. They noted that the ancient genomes were the same strain and “are identified as the most recent common ancestor of a major diversification commonly associated with the pandemic’s emergence.”
The journal article notes that previous research suggests warfare and trade networks may have helped spread the bacteria and resulting illness.
Can it be traced further?
The news study doesn’t mean the origin of Black Death has been settled entirely.
“I would be very cautious about stretching it that far,” Hendrik Poinar, evolutionary geneticist and director of the McMaster University Ancient DNA Center in Ontario, Canada, who was not involved in the study, told NPR. “Pinpointing a date and a specific site for emergence is a nebulous thing to do.”
He said because Y. pestis evolves slowly, the sample they found could have begun elsewhere in the region. But he called the findings significant.
Science Alert reported that “this new study, which suggests the Black Death emerged in Central Eurasia, is actually just the latest in a slew of archeological and paleoecological findings that are steadily rewriting our understanding of the plague.”
Before this, some of the same researchers had traced the roots back to a riverside town in Russia.