Skeletons’ teeth acted like time capsules from London’s Great Plague

While these three plagues all had different symptoms, were spread differently, and infected different amounts of people, there was one common factor: they were all caused by Y. pestis at different evolutionary stages.

In 1665, the Great Plague of London killed more than 75,000 people in the space of a year, nearly a quarter of the city’s population back then.

Past year during construction of the new Crossrail underground rail link beneath London, skeletal remains were found of people who had died from the disease after Liverpool Street excavation cut through the Bedlam Burial ground, which was used to burry infected residents between 1569 and the early 18th century.

Researchers are optimistic the findings will likely shed new light on the swift spread of the plague.

The 1665 Great Plague of London was caused by Yersinia pestis bacteria, thought to be spread by rodents, according to new research that looked at skeletons found past year in the New Churchyard area of the city.

The Max Planck Institute for the Science of Human History tested teeth from recovered dead bodies and found positive results of yersinia pestis in five out of 20 skeleton samples, the BBC reports. The enamel on the teeth serves as a great time capsule preserving genetic information of any bacteria present on the victim’s bloodstream during the time of death. The plague disappeared after the fire and never returned except for the ghost traces of the bacteria’s DNA.

We’ve finally gotten confirmation of what caused as many as 100,000 people to die in London centuries ago.

The same bacteria caused the Black Death, which killed an estimated 50 million people during the 14th century.

The Yersinia pestis DNA was found in the dental remains, which confirms they did die specifically due to the bubonic plague. “It was the same disease that kept coming back”, said Walker.

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. “We still need, however, to understand why the disease manifested itself in so many ways, and whether other pathogens made a significant contribution to these epidemics”. “The excavation also underlines the strength of custom and order in time of crisis, showing that plague burial, even in mass graves, could be controlled and orderly, with bodies in coffins laid neatly on each other – not quite the shamolic “plague pit” of popular discourse”.

What about you? You don’t have to worry about plague of any sort–great or small–if you hop into London.

“Looking at the DNA. could help tell us why the disease has changed in this way”, said Walker.