Researchers have discovered direct genomic evidence of the bacterium responsible for the "plague of Justinian" that was located in the eastern Mediterranean. This outbreak was first described 1,500 years ago. This discovery was made by an interdisciplinary team from the University of South Florida and Florida Atlantic University.
These institutions also had the collaboration of researchers from India and Australia. They identified Yersinia pestis, the microbe that causes the plague. The pathogen was located in a mass grave in the ancient city of Jerash, Jordan, near the epicenter of the pandemic.
The finding definitively links the pathogen with the "plague of Justinian", an event that was framed as the first pandemic (541 to 750 AD). It should be noted that for many years historians have deliberated on the causes of the outbreak that killed many people, transforming the Byzantine Empire. Despite the circumstantial evidence, direct proof of the microbe responsible had remained elusive.
Two recently published articles, led by the two academic institutions, provide the answers, offering a new perspective on one of the transcendental episodes in history.
The finding was presented in the journal Genes, and underlines the current relevance of the plague, that although it is rare, Yersinia pestis is still present throughout the world, and in fact in July a resident of northern Arizona died from pneumonic plague, the most lethal form of the bacterium, which frames it as the first of its kind in the United States since 2007 and last week another person in California tested positive for the disease.
In a statement, Dr. Rays H. Y. Jiang, the lead researcher on the studies and an associate professor at the USF School of Public Health, noted that for years they have relied on written accounts describing a devastating disease, but solid biological evidence of the plague's presence was unknown, providing their findings with the missing piece of the puzzle and giving the first direct genetic window into how the plague developed. pandemic in the Byzantine Empire.
The co-author and research professor at FAU's Harbor Branch Ocean Institute and National Geographic Explorer stated that using specific ancient DNA techniques they successfully recovered and sequenced genetic material from eight human teeth excavated in burial chambers beneath the ancient Roman hippodrome of Jerash, a city 320 kilometers from ancient Pelusium.
This site is relevant because the plague of Justinian first appeared in the historical record at Pelusium (now known as Tell el-Farama), in Egypt, before spreading throughout the Eastern Roman Empire.
It must be said that, while traces of the bacteria had been recovered, this was thousands of miles away, in small villages in Western Europe, with no evidence found within the empire itself or near the heart of the pandemic.
It should be clarified that the aforementioned sand had become a mass grave between the middle of the sixth century and the beginning of the seventh century, when written records describe a sudden wave of mortality.
Genomic analysis revealed that plague victims carried strains almost identical to Yersinia pestis, which would first confirm the presence of the bacterium in the Byzantine Empire between 550 and 660 AD. This genetic uniformity suggests a rapid and devastating outbreak, consistent with historical descriptions of a plague that caused dozens of lives.
The Jerash site, Jiang says, offers exceptional insight into how ancient societies responded to public health disasters. This location was one of the key cities of the Eastern Roman Empire and demonstrates how urban centers were likely overwhelmed.
A companion study published in Pathogens, also led by the universities, places the discovery of Jerash in a broader evolutionary context. By analyzing hundreds of ancient and modern genomes of the bacterium, including those recently recovered from the location. The researchers showed that the pathogen had circulated among human populations for millennia, before the Justinian outbreak.
The team also found that the pandemics of the later plagues, from the Black Death of the fourteenth century to the cases that still appear today, did not descend from a single ancestral strain; instead, they arose independently and repeatedly from long-standing animal reservoirs, erupting in multiple waves in different regions and times.