(Image: Werner Forman Archive/Bridgeman Images)

The secret of plague’s death toll is out. The high mortality rate seen during the Black Death in the 14th century may have been the result of poor general health rather than the strength of the bacterium.

The Black Death killed about 60 per cent of Europe’s population. That’s surprising as recent plague outbreaks weren’t as devastating.

“There is a huge difference in mortality rates,” says Sharon DeWitte at the University of South Carolina, even though 14th century and 20th century plagues were caused by the same bacterium, Yersinia pestis, and its genetics were similar in both outbreaks.


DeWitte believes that the high mortality rate in the 14th century may have been the result of a general decline in health. She examined skeletons in London cemeteries from the 11th, 12th and 13th centuries and found that more adults under the age of 35 were buried in the 13th century.

This suggests that people were dying younger before the Black Death arrived – probably because of famine and an increase in disease burden from other pathogens.

“Together with historical data, the picture that emerges is that the population was not doing well,” says DeWitte.

But Samuel Cohn, a historian from the University of Glasgow, UK, is not convinced.

“The wealthy were also dying in great numbers during the first outbreak of the Black Death [1347-51],” he says, noting that it is unlikely that they were in poor health.

Journal reference: American Journal of Physical Anthropology, DOI: 10.1002/ajpa.22806