Traces of DNA in tooth enamel confirm the presence of bubonic plague bacteria.
The pathogen responsible for wiping out nearly a quarter of London’s population between 1665 and 1666 has been identified for the first time. Scientists have confirmed the presence of DNA from Yersinia pestis, the bacterium that causes bubonic plague, on skeletons uncovered during excavation of a suspected Great Plague burial pit in Liverpool.
Around 42 skeletons of mostly young individuals under the age of 17, neatly stacked up to eight bodies high, were found in the pit. The bodies would have originally been encased in coffins, which have since rotted away. More than 3,300 people were buried in the cemetery where the pit was dug.
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To detect bacterial DNA, scientists focused on the skeletons’ teeth because, as Roff Smith of National Geographic explains, enamel “acts as a kind of time capsule in preserving the genetic information of any bacteria that was circulating in the individual’s bloodstream at the time of death.”
Sure enough, the teeth of five of the 20 skeletons analyzed contained traces of Y. pestis — the same bacterium that caused the 1348 Black Death epidemic and the 1855 bubonic plague outbreak in China.
“It’s significant because we had this famous, severe outbreak of plague in 1665, but until very recently, there was quite a lot of doubt about what had caused it,” senior Human Osteologist at the Museum of London Archaeology Don Walker, who was involved in sampling, told The Independent.
The scientists plan to sequence the recovered Y. pestis genome and compare it to remnants from the Black Death epidemic of the 14th century to understand how the pathogen evolved as it spread through Europe over centuries.
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