The 14th century Black Death pandemic, though to have reached Europe through China, killed 75 to 200 million people, or 30-60% of the affected population. The disease itself is caused by the bacterium Yersinia pestis (named after the French-Swiss bacteriologist Alexander Yersin), and is still endemic in some parts of the world.
The thing that’s been puzzling epidemiologists – as well as researchers from a number of other fields – for decades is why did the medieval epidemic happen when it happened, and why did it cause such devastation, while those of the 20th century did not. After all, the underlying cause was exactly the same in every single outbreak.
To figure this out, Sharon N. DeWitte, an Associate Professor at South Carolina University’s Department of Anthropology, who had already worked on the subject in the past, examined 339 human skeletons from the 11-12th centuries and 258 skeletons from the 13th century – all exhumed from a number of London cemeteries.
This, it was hoped, would provide some invaluable insight into the dynamics of the disease, as all previous analyses lacked data on the experiences of women and children, and demographic trends (survivorship and mortality rates) prior to 1270.
What the study author found was that, by the 13th century, the general health and survival rate of the European population had already been on steady decline, with more and more people dying before their 35th birthday.
According to DeWitte, this might be explained by the dreadful famines that’d been spreading around the continent at the time, as well as an increased burden of disease from other pathogens.
“Together, these results suggest that health in general was declining in the 13th century, and this might have led to high mortality during the Black Death. This highlights the importance of considering human context to understand disease in past and living human populations,” DeWitte argued in a paper, published in last month’s edition of the American Journal of Physical Anthropology.
So far, the thesis was challenged only by Samuel Cohen, a Historian from the University of Glasgow, UK, who pointed out that the wealthy, who were unlikely to be in poor health, were also dying in great numbers during the first outbreak in 1347-1351.
Although more research is clearly needed before we can say anything definitive, Professor DeWitte’s work on the subject has been noted by many of her colleagues, and constitutes a worthwhile addition to the ongoing work.