A landmark discovery by teams from two Florida universities has unearthed one of history's greatest mysteries — what caused the Plague of Justinian.
It killed up to 50 million people in the sixth century and altered the course of Western civilization. The scientists discovered microbes in the teeth of people buried in what is now Jordan.
The landmark discovery was led by teams at the University of South Florida and Florida Atlantic University, with collaborators in India and Australia. It identified Yersinia pestis, the microbe that causes plague, in a mass grave at the ancient city of Jerash, near the pandemic's epicenter.
The groundbreaking find definitively links the pathogen to the plague, marking the first recorded pandemic (AD 541 to 750) and resolving one of history's long-standing mysteries.
Justinian was the emperor of the Byzantine Empire (Eastern Roman) at the time who contracted the disease, but survived.
One of the study's authors is Rays Jiang, a biology professor at the USF. She says the finding shows that pandemics are repeating events that are driven, in part, by human behavior, such as migration from areas that have been infected.
"If you look at the victims, who got buried together, they're very different from each other," Jiang said. "We have new evidence to show that. They were not born locally. They grew up in other places. They came to Jerash to live in this urban center. And died together and buried together. "
"So, I think our study shows that the role of a human society and organization. The ancient urban center like Jerash, a city has drawn so many people together, it offers its own vulnerabilities."
The Plague of Justinian first appeared in the historical record in Pelusium (present-day Tell el-Farama) in Egypt before spreading throughout the Byzantine Empire. While traces of Y. pestis had previously been recovered thousands of miles away in small western European villages, no evidence had been found within the empire itself or near the heart of the pandemic.
"Using targeted ancient DNA techniques, we successfully recovered and sequenced genetic material from eight human teeth excavated from burial chambers beneath the former Roman hippodrome in Jerash, a city just 200 miles from ancient Pelusium," said Greg O'Corry-Crowe, co-author and a research professor at FAU Harbor Branch Oceanographic Institute.
The arena had been repurposed as a mass grave during the mid-sixth to early seventh century, when written accounts describe a sudden wave of mortality.
Jiang says there is proof that many of the victims came from different places in the Eastern Mediterranean, which may have helped spread the pandemic.
"This study particularly taught us that human society is an active agent in epidemics," Jiang said. "And the reason why plague has been here for a few thousand years and burst into flames into the recorded pandemic."
This isn't just ancient history. This pathogen was never eradicated. In July, a person died of the plague in Arizona.
"If we take a long view, then the plague has been there from Neolithic, Bronze Age, Iron Age to currently today," Jiang said. "We still have a U.S. plague deaths this year."
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