Plague: Britain’s oldest known cases discovered in mass burials | Cnn

Plague: Britain's oldest known cases discovered in mass burials |  Cnn

From the Francis Crick Institute

One of the sites where scientists found human remains containing the DNA of plague-causing bacteria was in Levens, County Cumbria, England.



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A team of researchers excavating mass burial sites in England has found DNA from the bacteria that caused the plague in human skeletal remains and are the oldest known cases of the disease in Britain.

Cases of Yersinia pestis date back 4,000 years, according to the paper published Tuesday in the journal Nature Communications.

Bacterial DNA is thousands of years older than the oldest strain discovered prior to this latest discovery. That stump, identified in 2018 at a burial site known as Edix Hill in Cambridgeshire, was 1,500 years old, according to study lead author Pooja Swali, a doctoral student at the Skoglund Laboratory at the Francis Crick Institute in London.

Samples of the plague-causing bacteria were found in two different mass burial sites: one in south-west England in the county of Somerset and the other in the north-west county of Cumbria, near the border between England and Scotland.

The distance between the sites suggested the disease was widespread during the Late Neolithic and Bronze Ages, Swali said.

The evidence of widespread transmission across such a large spatial area in just a few centuries is very intriguing and appears to be an aspect of the rapid movement of people, technologies and ideas during this period, said Dr. Benjamin Roberts, an associate professor of archeology researching later European prehistory at Durham University in the UK. He was not involved in the study.

How do researchers spot 4,000-year-old bacteria? The team took samples from the skeletal remains of 34 individuals at the two sites, according to the study.

The researchers drilled through the teeth of these ancient people and extracted the dental pulp, which can trap the DNA remnants of infectious diseases.

The ability to detect ancient pathogens from degraded samples dating back thousands of years is incredible, Swali said. These genomes can inform us of the spread and evolutionary changes of pathogens in the past and hopefully help us understand which genes may be important in the spread of infectious diseases.

Using genetic analysis, the researchers determined that there were two distinct periods when the plague appeared in Britain: the disease emerged before or about 4,000 years ago and again about 1,500 years ago, said Dr. Lee Mordechai, a history professor at the Hebrew University of Jerusalem who was not involved in the study.

When it comes to the disease, there’s still a lot scientists don’t know, including how it spread, Swali said.

The strain of Yersinia pestis found at burial sites did not contain the gene that would allow it to be spread through fleas, a trait possessed by the strain that caused the pandemic known as the Black Death that later ravaged medieval Europe in the 14th century , he added. .

And science may never really know the severity of the plague 4,000 years ago when it came to humans, Roberts said.

Researchers can’t say whether the disease caused by the bacteria would have been mild or fatal, he added. And people at the Somerset site appeared to have died of trauma and not disease, according to the research.

The temptation is always to theorize a doomsday scenario of the medieval Black Death, but we simply can’t justify it with the evidence we have, Roberts said in an email.

The quest presents lessons for today.

The findings demonstrate the importance of scholars working together across disciplines, as archaeologists and paleogeneticists did in this work, Mordechai said.

The report also shows that large-scale disease transmission dates back to prehistoric times, he added.

More recent pandemics like Covid, AIDS or the Spanish flu are recent cases of a recurring phenomenon, Mordechai said in an email.

And while there are historical records of plague outbreaks, ancient DNA could potentially give us a glimpse even further back, Swali said.

Future research will do more to understand how our genomes have responded to such diseases in the past and the evolutionary arms race with the same pathogens, which may help us understand the impact of diseases in the present or future, he said in a statement.

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