Plague DNA has been found 4,000 years old, making it the oldest evidence of the disease in Britain.
One said the researchers’ discovery could help understand genes “important in the spread of infectious diseases”.
Scientists from the Francis Crick Institute (FCI) have identified three cases of Yersinia pestis – the bacteria that causes plague – in human remains.
Two were discovered in a mass grave at Charterhouse Warren in Somerset, and the other in a circular memorial in Levens, Cumbria.
Working with local groups and the University of Oxford, the team took small skeleton samples from 34 individuals across the two sites.
Then they drilled the teeth and extracted the dental pulp, which can trap DNA remnants of infectious diseases.
Being able to detect “ancient pathogens from degraded samples” long ago was “incredible,” said author Pooja Swali, a PhD student at the Federal Institute for Migration.
She added: “These genomes can inform us about the prevalence and evolutionary changes of pathogens in the past, and we hope they will help us understand genes that may be important in the spread of infectious diseases.
“We see that this Y. pestis strain, including the genome from this study, is losing genes over time, a pattern that has emerged with subsequent epidemics caused by the same pathogen.”
Previously, plague was identified in several individuals from Eurasia between 5,000 and 2,500 years before the present (BP).
The researchers pointed out that it was unprecedented in Britain during that period.
Its wide geographic spread is thought to indicate that it was easily transmitted.
“This research is a new piece of the puzzle in our understanding of the ancient genomic record of pathogens and humans, and how we are involved in evolution,” said Pontus Skoglund, Group Head of the Paleontological Genomes Laboratory at the International Research Institute.
“Future research will do more to understand how our genomes responded to such diseases in the past, and the evolutionary arms race with the pathogens themselves, which can help us understand the impact of diseases in the present or in the future.”
The results are published in the journal Nature Communications.
