Forensic Case Files: Black Death Victims Uncovered in London

A burial ground containing thirteen sets of remains was recently discovered in London during excavations for the Crossrail project, the expansion of London’s existing public transit rail lines. Located in Farringdon—an area of downtown London—in one of the rare undeveloped sections of the city, the remains were uncovered in a location suspected to be one of the city’s emergency burial grounds used during the 14th century plague known as the ‘Black Death’. Open in 1349 and possibly receiving up to 50,000 dead during the next three years, the Farringdon burial ground was referred to in historical texts as ‘no man’s land’. Closed in the 1500’s, its exact location was lost to time until now.

Laying a mere eight feet underground, the skeletons were discovered in two neat rows. The burial pattern indicates that this area of the cemetery was used at the beginning of the plague, when death rates were low and individual burials were common. In later years, the overburdened and fearful population simply discarded the constant stream of bodies into mass graves. An indication of the mindset of the population at the time—in 1347, the average number of wills registered in London was only 20; but by 1349, that number ballooned to 370. Simply put, the English expected to die, and wanted no contact with the sick or the dying that lessened their chances of survival.

Osteologists and archeologists from the Museum of London are already excavating and removing the remains for study. They plan to extract plague DNA from the tooth pulp of the victims and hope to be able to sequence the bacteria’s genomic DNA, possibly mapping it as the ‘mother of all modern plague species’. The remains will also give scientists a glimpse into life in the 14th century—the wear patterns on the bones reveal it was a life of heavy labour, but other indicators will give information about their general health and stature.

Yersinia pestis, the bacteria responsible for the Black Plague, originated in China and was brought to Europe in the mid-14th century. It started in Persia in 1346 and then spread through southern Europe in 1347 before moving north into the rest of Europe and Russia over the next five years. It arrived in London and the south of Britain in 1348 before spreading to the rest of the country and beyond. By the time the epidemic played out, an estimated 75 – 200 million people, roughly 30 – 60% of Europe’s population were dead. Carried by rats, and transmitted by the rodents’ fleas, Y. pestis sickens it’s victims by suppressing the body’s normal immune response. It directly affects immune cells in the blood and evades the body’s response by hiding and replicating in the lymph nodes, creating the characteristic black buboes or swollen lymph nodes that often oozed pus and blood. Medieval physicians often lanced the buboes, exposing the unsuspecting practitioner to the infectious contents and spreading the plague further. The number of infections dramatically decreased in Britain after 1350, but smaller outbreaks continued for the rest of the 14th century. A second major plague took place between 1665 and 1666 in London, but by the late 18th century, it had mostly disappeared from Europe.

An electron micrograph of a cluster of Yersinia pestis bacteria.

Why the plague died out has never been definitively answered, but there are several possibilities. Those that survived the first wave of the plague in 1348 became immune to further infections, leaving fewer susceptible to future infection. The 1348 wave of the plague mostly infected adults, but later waves—1361 for instance—primarily infected children who were not alive in 1348 and had no resistance to the bacteria. Later on, herd immunity (the greater immune population protecting the lesser susceptible population simply by their inability to become infected) would have protected younger members of the population. There is also a theory that the fleas that carried Yersinia pestis only lived on black rats. When larger brown rats out-competed the black rats in Europe, there were fewer carriers for the plague. 

Photo credit: Crossrail, Rocky Mountain Laboratories/Wikimedia Commons, and the Toggenburg Bible.


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