The Black Death, which afflicted Europe, Western Asia and North Africa from 1347 to 1352, is the largest and most notorious pandemic in history. Scholars have estimated that about 50% of the European population was killed by it.

However, recent research by Sapienza University and the Max Planck Institute for the Science of Human History, published in the journal Nature Ecology and Evolution, refutes past historical reconstructions and shows that the mortality rate of the Black Death in Europe was not as high as previously thought. Above all, it shows how its spread across the old continent was uneven, hitting some regions hard and others less so.

These results have been achieved by analysing fossil pollen from 261 sites (lakes, bogs and fens) in 19 European countries.

The study of pollen has enabled us to understand the changes in landscapes and agricultural activities between 1250 and 1450 AD, i.e. 100 years before and 100 years after the pandemic.

The international team of scholars led by the Paleo-Science and History group of the Max Planck Institute for the Science of Human History and coordinated by Alessia Masi, a researcher at the Department of Environmental Biology and historian Adam Izdebski, used a new approach, called Big-data paleoecology (BDP).

The research team analysed 1634 samples containing pollen to observe the types and quantities of plants grown and to determine the extent of agricultural activities and the presence of wild plants before and after the pandemic. Land use due to farming activities and deforestation in pre-industrial times depended on the availability of labour: highly cultivated land shows the presence of large populations; on the contrary, uncultivated areas show their absence.

The results show significant variability in land use and thus in mortality rates. In particular, regions such as Scandinavia, France, south-west Germany, Greece and central Italy show a substantial agricultural decline, reflecting the high mortality rates already attested in many medieval sources. At the same time, many areas, including much of Central and Eastern Europe and Western Europe such as Ireland and the Iberian Peninsula, experienced continuity or even growth in land-based activities.

The research shows that in order to study mortality rates in a specific region and measure changes in landscapes, it is important to use new approaches, such as BDP.

To date, many of the sources used to quantify the phenomenon have come from urban areas where it was undoubtedly easier to collect information and keep records but were at the same time characterised by crowding and poor hygienic conditions. However, it is likely that by the middle of the 15th century, more than 75% of the population in every European region was rural.

"The significant variability in mortality that our BDP approach identifies remains to be explained, but local cultural, demographic, economic, environmental and social contexts must have influenced the prevalence, morbidity and mortality given by Yersinia pestis," says Laura Sadori, coauthor of the study with Cristiano Vignola of the Department of Environmental Biology and Lucrezia Masci of the Department of Earth Sciences.

The differences in mortality across Europe show that the Black Death was a dynamic disease, with cultural, ecological, economic and climatic factors influencing its spread and impact. "There is no single pandemic model that can be applied to any place, at any time, without taking into account the context," argues Adam Izdebski. "Pandemics are complex phenomena that have regional and local histories. We have seen this with COVID-19, now we have demonstrated it with the Black Death."

References:

Palaeoecological data indicates land-use changes across Europe linked to spatial heterogeneity in mortality during the Black Death pandemic - A. Izdebski, P. Guzowski, …A. Masi  - Nature Ecology & Evolution (2022)

Further Information

Alessia Masi
Department of Environmental Biology
alessia.masi@uniroma1.it

Laura Sadori
Department of Environmental Biology
laura.sadori@uniroma1.it