The bones of people who died from the Black Death have been found in the course of extending London's rail system. One interpretation of the what has been found may upend centuries of teaching about how the plague spread. The remains have also provided insight into the poor state of Londeners' health even before the disease hit.

 

In 1348 London was hit by probably the most devastating plague in its history. It is estimated 60% of Londoner's died from it in the space of less than a year. Under such circumstances, not a lot of care was taken of the dead and many were dumped in mass graves outside what was then the city. Over time the exact location was lost, but while excavating for the London Crossrail skeletons have been found, and Crossrail's lead archaeologist Jay Carver told the BBC , "Further excavations will follow to see if - as we expect - we are coming across a much bigger mass burial trench” located under the Charterhouse Square. If so, it will, “solve a 660-year old mystery.”

 

But the first research on the bones found has also challenged the idea that the plague spread via fleas carried by rats. Traces of Yersinia pestis, the bacterium that causes the Black Death, have been extracted from the teeth of some of the skeletons found beneath the square. The puzzling thing they found was not that the DNA had some particularly lethal feature, but that it appeared the same as that from a 2012 outbreak in Madagascar.

 

In a soon to be released documentary Dr Tim Brooks from Public Health England's Rare and Imported Pathogens Laboratory will argue that the similarity with the Madagascan bacterium proves that the Black Death was not bubonic plague, as has been thought, but pneumonic plague. Both are caused by the Y Pestis bacteria, but while the one is spread by fleas, the other is transmitted directly from human to human through the air.

 

Brooks' work has yet to be published in a peer reviewed journal and may face considerable opposition. However, he argues that the pattern of spread of the Black Death is far more in keeping with pneumonic plague than its bubonic sibling, Transmission through the air can happen much more quickly than via fleas. Brooks told  The Guardian,  "As an explanation [rat fleas] for the Black Death in its own right, it simply isn't good enough. It cannot spread fast enough from one household to the next to cause the huge number of cases that we saw during the Black Death epidemics."  

 

Cases of pneumonic plague have been recorded, but the lung infections that distinguish it were thought to be much rarer than the swollen areas under the armpits and between the legs of the bubonic version. Musician Louis Heyligen, who died of the plague in France in 1348 described it as taking “three forms” and distinguished between those whose lungs were infected and those with boils under the arms or groin, suggesting both may have been factors at the time. Unsurprisingly Heyligen didn't fuss about a census of which was the dominant mode of transmission.

 

Modern outbreaks of Y pestis, if untreated, are as deadly as the 14th Century version. Today the death toll is around 2000 a year, almost entirely in places where antibiotics are not widely available.

 

Examination of the bones by Don Walker of the Museum of London Archeology reveals that many of the skeletons were malnourished and one in six had rickets. The defective bone mineralization of rickets can be caused by a number of things, most commonly inadequate vitamin D or calcium, particularly as a result of famine during early childhood. Agricultural improvements in previous centuries had led to substantial population growth in Europe, and by the early 14th Century food shortages were common.

 

Many of the bodies found also showed signs of back damage in keeping with hard manual labor, and minerals incorporated in their bones indicate 40% grew up away from London. The cemetery was reused during a subsequent outbreak more than 80 years later. Many of the skeletons from 1430s had injuries consistent with surviving violence, leading to the suggestion that the breakdown in society caused by the first round of plague was reflected in common anti-social behavior decades later.

 

Ground-penetrating radar operated by the University of Keele has indicated the presence of far more bones and a building at the same level under the square. It is thought several thousand bodies may be found there.