The Black Death (1347–1352 AD) is the most infamous pandemic in human history. Advances in ancient DNA research have enabled researchers to identify the bacterium behind this terrible historical event ( Yersinia pestis ), and traced its evolution over time, however there are still huge gaps in knowledge about the plague’s demographic impacts. For the most part researchers have had to rely on medieval written sources from some parts of Western Europe to gain insight on how deadly the Black Death was. Now, an international team of researchers have pioneered a novel approach to evaluate the scale of the Black Death’s mortality across Europe, with some surprising results.
Historians estimate that the Black Death which plagued Europe, West Asia, and North Africa from 1347-1352 killed half of Europe’s population at the time. The aftereffects of the plague have been credited with changing religious, political, cultural, and economic structures, and even leading to such major transformations as the Renaissance. But what if the devastating mortality rates of the Black Death across Europe were not as widespread as generally believed?
Researchers have explored this question with an innovative approach and their results are rewriting the story of the Black Death’s impact across Europe.
The people of Tournai bury victims of the Black Death, circa 1353. ( Public Domain )
Pioneering a New Approach to Answer Questions about the Past
While it is generally accepted that the Black Death killed tens of millions of people in an Afro-Eurasian pandemic in the mid-14th-century, there are questions on just how devastating it was on different populations. So, a global team of researchers, led by the Palaeo-Science and History group at the Max Planck Institute for the Science of Human History, have used ‘big data palaeoecology’ to analyze how deadly the Black Death really was across Europe.
In practice, this means that they collected and evaluated pollen data on landscape change from sites across 19 modern European countries, looking for signs if the landscape changes reflect the hypothesis that half of Europe’s population died within a few years of the plague’s outbreak, or not.
The Max Planck Institute for the Science of Human History explains that studying pollen and fossilized plant spores “is a powerful tool for uncovering the demographic impacts of the Black Death” because it can reveal which plants were growing and how much they grew in a region. With this information in hand, the researchers could see if agricultural activities in each region continued after the area was hit by the plague, or if wild plants regrew while the human population was reduced and there were less rural workers available to farm the land or clear native plants for building projects.
An explanation of the Big Data Palaeoecology approach used in the study to verify Black Death mortality levels. (A.I., T.N., Hans Sell and Michelle O’Reilly/ Nature Ecology & Evolution, 2022 )
Are Black Death Mortality Rates as Widespread and Devastating as Historians Believe?
Through their analysis of pollen samples from 261 sites ranging from 1250 and 1450 AD – roughly 100 years before to 100 years after the plague – they’ve found that although there were some regions that were devastated by the Black Death, as commonly believed, it didn’t have the same impact on mortality rates across the board. In their paper they write:
“While we can confirm that the Black Death had a devastating impact in some regions, we found that it had negligible or no impact in others. These inter-regional differences in the Black Death’s mortality across Europe demonstrate the significance of cultural, ecological, economic, societal and climatic factors that mediated the dissemination and impact of the disease.”
Specifically, their results show that Scandinavia, France, southwestern Germany, Greece, and central Italy had sharp declines in agricultural activity, supporting the high mortality rates in these regions as they are presented by medieval texts. But the results also suggest that areas such as Central and Eastern Europe and parts of Western Europe, including Ireland and Iberia, had lower mortality rates and their agricultural work continued, suggesting the plague had negligible or no impact in those regions.
Regional scenarios of Black Death demographic impact. Colors reflect centennial-scale changes in the cereal pollen indicators. Background map with political borders of 14th-c. Europe. (Hans Sell, Michelle O’Reilly, Adam Izdebski; Izdebski et al./ Nature Ecology & Evolution, 2022 )
A Dynamic Disease
Alessia Masi from the Max Planck Institute for the Science of Human History and La Sapienza University in Rome suggests that “local cultural, demographic, economic, environmental and societal contexts would have influenced Yersinia pestis prevalence, morbidity and mortality” in these areas, but notes that the significant difference between the Black Death mortality rates in the different regions “remains to be explained.”
Adam Izdebski, the leader of the Palaeo-Science and History group at the Max Planck Institute, emphasizes the importance of looking at local sources, including the big-data paleoecology because, “Pandemics are complex phenomena that have regional, local histories. We have seen this with COVID-19, now we have shown it for the Black Death.”
As their research demonstrates, the Black Death was a dynamic disease and cultural, ecological, economic, and climatic factors all played a role in the level of mortality that resulted from this plague across Europe.
The study results are presented in the paper ‘Palaeoecological data indicates land-use changes across Europe linked to spatial heterogeneity in mortality during the Black Death pandemic’ in the journal Nature Ecology & Evolution .
Top Image: A new study shows that the Black Death mortality rates were not the same across Europe. Source: illustrissima /Adobe Stock
By Alicia McDermott