Scientists have, for the very first time, obtained direct genetic evidence confirming the presence of the bacterium responsible for the Plague of Justinian, recognized as the earliest documented pandemic in human history, right in the Eastern Mediterranean region where the catastrophe was initially reported almost 1,500 years ago.
This pioneering achievement, spearheaded by a collaborative team of experts from the University of South Florida and Florida Atlantic University, alongside partners from India and Australia, pinpointed Yersinia pestis, the pathogen that triggers plague, within a mass burial site located in the ancient Jordanian city of Jerash, situated close to the outbreak’s central zone. This revolutionary detection firmly connects the microbe to the Justinian Plague, which defined the initial pandemic era spanning AD 541 to 750, thereby settling a persistent enigma from antiquity.
Historians have debated for hundreds of years the underlying cause of this catastrophic event, which claimed the lives of tens of millions, profoundly transformed the Byzantine Empire, and fundamentally shifted the trajectory of Western civilization. Although indirect clues existed, concrete biological confirmation of the culpable agent had always been absent, representing a crucial gap in the narrative of global pandemics.
Two recently released studies, spearheaded by researchers from USF and FAU, deliver these eagerly awaited resolutions, shedding fresh light on one of the most pivotal chapters in humanity’s past. Moreover, this breakthrough emphasizes the continued significance of plague in contemporary times: though uncommon, Y. pestis persists in circulating globally. For instance, in July, a person from northern Arizona succumbed to pneumonic plague, the deadliest manifestation of Y. pestis infection, representing the first such death in the United States since 2007. Remarkably, just a week ago, another case was confirmed in California.
‘This finding delivers the definitive confirmation we’ve sought regarding Y. pestis at the core of the Plague of Justinian,’ stated Rays H. Y. Jiang, PhD, the principal investigator leading these investigations and an associate professor at the USF College of Public Health. ‘Over centuries, we’ve depended on textual descriptions of a ruinous illness, yet we had no solid biological proof of plague’s existence. Our results fill that critical void, granting the inaugural direct genetic perspective on the progression of this pandemic at the empire’s vital center.’
The Plague of Justinian entered historical records initially at Pelusium, now known as Tell el-Farama in Egypt, before rapidly disseminating across the Eastern Roman Empire, also called the Byzantine Empire. Although remnants of Y. pestis had been detected previously in remote western European hamlets thousands of miles distant, no such traces had ever surfaced inside the empire or proximate to the pandemic’s origin point.
‘Employing specialized ancient DNA methodologies, we managed to extract and sequence genetic sequences from eight human teeth unearthed from burial vaults under the ancient Roman hippodrome in Jerash, a location merely 200 miles from the old Pelusium,’ explained Greg O’Corry-Crowe, PhD, a co-author and research professor at FAU’s Harbor Branch Oceanographic Institute, who also serves as a National Geographic Explorer.
This arena, originally designed for spectacles and public gatherings, was converted into a communal grave during the mid-sixth to early seventh centuries, aligning precisely with documented surges in mortality described in historical texts.
Detailed genomic examination disclosed that the individuals interred there harbored almost indistinguishable strains of Y. pestis, providing the first irrefutable evidence that the bacterium was active within the Byzantine Empire from AD 550 to 660. The striking genetic similarity points to a swift and overwhelmingly lethal epidemic, mirroring the vivid accounts of widespread fatalities in ancient sources.
‘The Jerash archaeological site furnishes a unique perspective on how ancient communities coped with public health crises of immense scale,’ noted Jiang. ‘Jerash stood as a prominent urban center in the Eastern Roman Empire, a vital nexus for commerce boasting impressive architecture. The transformation of a structure meant for leisure and communal prestige into an emergency burial ground illustrates how major cities were undoubtedly overrun during the crisis.’
An accompanying investigation, similarly directed by teams from USF and FAU, situates the Jerash evidence within a broader evolutionary framework. By scrutinizing hundreds of Y. pestis genomes from both ancient and contemporary sources, including the novel sequences from Jerash, the scientists demonstrated that this bacterium had been persisting in human groups for thousands of years prior to the Justinian event.
Furthermore, the analysis revealed that subsequent plague outbreaks, ranging from the fourteenth-century Black Death to isolated incidents occurring in modern times, did not stem from one unified progenitor strain. Rather, these epidemics emerged separately and recurrently from enduring reservoirs in animal populations, manifesting in diverse waves across various geographies and periods. This cyclical phenomenon sharply diverges from the SARS-CoV-2 pandemic, known as COVID-19, which traced back to a solitary zoonotic jump and subsequently propagated mainly via human contacts.
Collectively, these transformative discoveries redefine our comprehension of pandemic origins, recurrences, and dissemination patterns, as well as the reasons they endure as recurring elements in human society. The work highlights that pandemics constitute not isolated tragedies in history, but recurrent biological occurrences propelled by factors such as human gatherings, travel, and ecological shifts, all of which echo strongly in our current era.
‘This project was intellectually captivating and deeply personal,’ reflected O’Corry-Crowe. ‘It presented a remarkable chance to explore human history via ancient DNA amid our own experience of a worldwide pandemic. Equally impactful was collaborating with remains from ancient individuals who lived, endured hardship, and perished long ago, employing cutting-edge science to reconstruct and disseminate their narratives. It serves as a profound acknowledgment of our common human experience through the ages and a powerful affirmation of science’s capacity to amplify voices silenced by time.’
Although distinct from COVID-19 in many ways, both plagues illuminate the persistent connection between societal interconnectedness and vulnerability to pandemics, alongside the sobering fact that certain pathogens resist complete elimination.
‘Humanity has contended with plague across several millennia, and fatalities persist even now,’ Jiang observed. ‘Similar to COVID-19, it keeps adapting, and efforts to control it clearly fall short of eradication. Vigilance is essential, yet the danger endures indefinitely.’
Leveraging the momentum from the Jerash advancement, the research group is now broadening its scope to include sites in Venice, Italy, particularly the Lazaretto Vecchio, a historic quarantine facility and among the planet’s most crucial plague burial grounds. Over 1,200 samples from this Black Death-period mass grave are currently archived at USF, presenting an unparalleled platform to examine the interplay between nascent public health strategies, microbial adaptation, metropolitan fragilities, and enduring cultural recollections.
