An analysis of nearly 600 skeletons from London, UK, buried in the periods before and after the black death, finds that survivorship improved in the aftermath of this medieval plague.
Between 1347-1351, the black death killed an estimated 30-50% of the European population. This was the first outbreak of medieval plague in Europe and the ensuing tens of millions of deaths resulted in broad social, demographic and economic changes.
Previous research on skeletons from the East Smithfield Black Death cemetery in London has suggested that, although the disease seemed indiscriminate in its culling of the European population, people who already had frail health – exhibited by signs of physiological stress in the skeletons – had a much higher mortality rate than healthier citizens.
After this initial outbreak of what is now known as bubonic plague, mortality rates for subsequent plague outbreaks were much lower than during the 4-year period of the black death.
This has led researchers – such as Dr. Sharon DeWitte from University of South Carolina, author of the new study – to wonder whether heightened immune responses or reduced disease susceptibility might have been selectively favored during the black death, resulting in a population of survivors who were more healthy overall than the pre-epidemic population.
“By targeting frail people of all ages, and killing them by the hundreds of thousands within an extremely short period of time, the black death might have represented a strong force of natural selection and removed the weakest individuals on a very broad scale within Europe,” DeWitte writes.
However, other factors in the post-black death era could have contributed to the fall in mortality and improvements in standards of living that followed. Not least of these, depopulation reversed the pre-epidemic problem of an excess population that did not have the resources to sustain itself. A major redistribution of wealth occurred due to the newly competitive employment market, where wages rose and the cost of foods, goods and housing fell.
To establish whether the population of London was physically healthier after the black death, Dr. DeWitte compared nearly 600 skeletons of London citizens who died between 1000-1300 with those that died after the plague, in the period 1350-1538.
Dr. DeWitte found that her post-black death sample had a higher proportion of older adults. A hazards analysis also found lower mortality risks in the post-black death period. Taken together, these findings suggest that health must have improved after the black death.
Although an increase in migration of healthy workers to London after the black death could have contributed to these improvements in overall mortality, DeWitte points out that migration to London was also common during the famines that preceded the black death.
Therefore, both of her samples would have likely included a mixture of immigrants and native Londoners.
Also, she says, because the devastation caused by the black death was mostly consistent across nearly all of Europe, any migrants into London would have consisted of black death survivors and their descendants to the same extent as London’s native population.
In conclusion, DeWitte says:
“This study suggests that even in the face of major threats to health, such as repeated plague outbreaks, several generations of people who lived after the black death were healthier in general than people who lived before the epidemic.”
In January, Medical News Today reported on a study that found the black death and the Justinian plague – which occurred 800 years earlier in Europe – were caused by different strains of the same bacterium.