Long before the “Black Death” decimated Europe in the 14th century, the bacterium that causes the plague was already lurking on the continent. Two years ago, scientists found the bacteria, called Yersinia pestis, in 5,000-year-old human remains in Latvia—the oldest strain on record.
Now, researchers have uncovered the earliest known evidence of the plague in Britain, in DNA found in human teeth dating to 4,000 years ago, according to a study published Tuesday in the journal Nature Communications.
The finding that the plague-causing bacteria had spread to Britain at this time isn’t surprising, since established connections did exist between the island and continental Europe, says Monica Green, a historian of medicine and health and an independent scholar, to New Scientist’s Soumya Sagar. “Still, the fact that what is presumed to be a rodent disease was capable of migration to this degree is notable,” she tells the publication.
Scientists suggest the lineage of Y. pestis was significantly contagious—they found the bacteria in two separate locations in England.
“The evidence of widespread transmission across such a vast spatial area in just a few centuries is very interesting and seems to be one aspect of the rapid movement of people, technologies and ideas during this period,” Benjamin Roberts, an archaeologist at Durham University in England who was not involved in the research, tells CNN’s Madeline Holcombe.
Humans can contract the plague via flea bites, infectious cough droplets and contact with body fluids or tissue of a plague-infected animal, according to the Centers for Disease Control and Prevention.
The disease has several different forms—flea bites cause the bubonic form, while human-to-human spread causes the pneumonic form. The bubonic plague triggered the 14th-century pandemic, which killed at least one-third of Europe’s population, writes the Guardian’s Ian Sample. The bacterial DNA in the new study, as well as other genomes from across Eurasia at the time, lacked a gene that played a role in transmission by fleas, according to the paper.
Europe’s 14th-century pandemic was the second of three pandemics caused by the plague. The first occurred in the 6th century C.E., while the third took place in the late 19th and early 20th centuries.
For the new study, the researchers examined the teeth of 34 early Bronze Age people in Britain. The remains were from Charterhouse Warren, Somerset, in southwest England and Levens Park, Cumbria, in northwest England.
Two of the 30 total people from the Charterhouse Warren site—children around 10 and 12 years old—had the bacterium in their teeth, as well as a 35- to 45-year-old woman from the Levens Park site. The bacterial strain was almost identical to one previously found in Germany that dates to around the same time, Pooja Swali, first author of the new paper and a researcher at the Francis Crick Institute in England, tells New Scientist.
All three people’s remains were around 4,000 years old. It’s possible that other remains examined in the study contained evidence of the plague, though the researchers were unable to detect it, according to the paper.
The analysis can’t determine the severity of the disease caused by the bacteria, Roberts tells CNN. “The temptation is always to theorize an apocalyptic Medieval Black Death scenario, but we simply can’t justify that with the evidence we have,” he says to the publication.
However, it’s unlikely that the people in the mass burial site at Charterhouse Warren died from the plague, the authors write. The remains were dismembered and showed signs of trauma right before death, James Ashworth writes for London’s Natural History Museum.
“It is possible that the trauma inflicted on the group as a whole had something to do with the fact that plague was circulating in the group,” Green tells New Scientist. “There are, in fact, other plague-related burials in medieval Europe suggesting fear-based responses to plague outbreaks.”