Was the Black Death the most devasting pandemic ever? Probably yes, but not everywhere

A new palaeoecological study in the journal Nature Ecology and Evolution evaluated changes in land-use in Europe in the period of 1250-1450 CE through a continental-wide analysis of fossil pollen data. In this way, it assessed the impact of the most devasting pandemic in human history, the Black Death. The international research group made up of ca. 60 researchers analyzed 1,634 pollen samples from 261 sites in 19 modern European countries and developed a new method of investigating spatial patterns of landscape change. Results reveal a geospatially diverse Europe consisting of regions where significant rewilding occurred and others where the cultural landscape does not seem to have suffered any land abandonment. The study demonstrated for the first time that the Black Death did not impact all regions equally: some regions experienced a devastating demographic collapse, while other parts of Europe had negligible or no impact at all.

The Black Death is a zoonotic pandemic that hit Europe, West Asia, and North Africa from 1347 to 1352 CE, sparking the second plague pandemic that lasted until the 18th c. CE. The disease resulted in high mortality traditionally estimated by historians of up to 50% of the total European population. However, for most of Europe, there is a lack of scientific evidence that addresses the actual demographic impact of the most devastating pandemic experienced by humans in historical times.

A new palaeoecological study published in Nature Ecology and Evolution developed a large-scale scientific approach (Big Data Paleoecology) based on pollen records, to assess the demographic impact of past pandemics, and applied it to the Black Death. The reconstruction of the spatial pattern of landscape change demonstrated that the Black Death's mortality in Europe was not as universal or as widespread as long thought. The international team of researchers headed by the Palaeo-Science and History group at the Max Planck Institute for the Science of Human History, produced a continental-wide meta-analysis using 1,634 fossil pollen samples from 261 sites in 19 modern-day European countries to determine how landscapes and agricultural activity changed during the Black Death pandemic.

"The significant variability in mortality that our Big Data Palaeoecology (BDP) approach identifies remains to be explained, but the local cultural, demographic, economic, environmental and social contexts must have influenced the prevalence, morbidity, and mortality given by Y. pestis" say Alessia Masi, CO-PI of the PSH group, and Laura Sadori, full professor of Systematic Botany, responsible of the Paleopalynology and Archaeobotany laboratory in Sapienza, Rome.

Scandinavia, most of France, southwestern Germany, Greece, and central Italy, experienced a sharp demographic collapse described by medieval historical sources. This is reflected in changes in the plants which shifted from agricultural fields to shrubs and forested lands. On the other hand, many regions, including much of Central and Eastern Europe as well as Ireland and Spain, show evidence for continued agriculture and uninterrupted land-use practices.

"The high mortality experienced by many countries caused a diffuse land abandonment followed by a large-scale expansion of forest ecosystems in the second half of the 14th c." explains Gianluca Piovesan, full professor of Landscape Ecological Planning at the University of Tuscia, Viterbo. "The Middle Ages was a period of diffuse deforestation and exploitation of forests. The cessation of agricultural and herding activities led to the restoration and expansion of natural forest ecosystems which have become some of the old-growth forests that still survive today in the Apennine chains".

The wild vegetation regrowth as a consequence of reduced human pressures is an ecological process called rewilding. In the case of the Black Death, the rewilding was due to the demographic collapse of certain European regions. Today, a new rewilding wave is characterizing many European rural areas, this time due to the marginality of the rural economy and the resulting depopulation. "Countries which experienced rewilding during the 14th c. went through natural reforestation and the restoration of multiple ecological services that modern and contemporary societies have enjoyed" says Jordan Palli, Ph.D. student in Ecology and Paleoecology at the University of Tuscia, who was one of the key scientists collecting pollen data for the meta-analysis together with Lucrezia Masci and Cristiano Vignola.

This study is unique also in terms of the huge amount of research work of dozens of scientists that it builds on. "Mere counting of 1634 pollen samples in a lab would take some 20-25 years of work—a lifetime's project! But if you think of 261 sites, and the fieldwork, sampling, processing, dating, etc. - all that needs to be done—a scientist who would like to carry it all by herself would have to start roughly at the time of the Black Death in order to be finished today!"—observes Adam Izdebski, a historian from the Max Planck Institute for the Science of Human History in Jena and the lead author of the study.

"Big data has contributed to advances in many areas of science. Palynological datasets from this interdisciplinary research must be increasingly used to understand long-term human-plant interactions and environmental responses to changes in land use and climate. The more we study the past, the more we understand the present, and we find that generalizations are only vague reconstructions" say Anna Maria Mercuri and Assunta Florenzano of the Laboratory of Palynology and Paleobotany at the University of Modena and Reggio Emilia.

Studies like this one are important for understanding the magnitude of past large-scale events in forest dynamics, the history of which is seen in our landscape even today. It also demonstrates the importance of cross-disciplinary studies to address complex issues involving the past and present human society and its deep connection to the natural environment. Cultural, ecological and economic factors influence the long-running relationship between humans and nature and the understanding of such long-term interactions represents a first step toward a peaceful and respectful partnership with nature.

More information:
Title: Palaeoecological Data indicates land-use changes across Europe linked to spatial heterogeneity in mortality during the Black Death pandemic
Authors: Izdebski A., Guzowski P., Poniat R., Masci L., Palli J., Vignola C., Bauch M., Cocozza C., Fernandes R., Ljungqvist F.C., Newfield T., Seim A., Abel-Schaad D., Alba-Sánchez F., Björkman L., Brauer A., Brown A., Czerwiński S., Ejarque A., Fiłoc M., Florenzano A., Fredh E.D., Fyfe R., Jasiunas N., Kołaczek P., Kouli K., Kozáková R., Kupryjanowicz M., Lagerås P., Lamentowicz M., Lindbladh M., López-Sáez J.A., Luelmo-Lautenschlaeger R., Marcisz K., Mazier F., Mensing S., Mercuri A.M., Milecka K., Miras Y., Noryśkiewicz A. M., Novenko E., Obremska M., Panajiotidis S., Papadopoulou M.L., Pędziszewska A., Pérez-Díaz S., Piovesan G., Pluskowski A., Pokorny P., Poska A., Reitalu T., Rösch M., Sadori L., Sá Ferreira C., Sebag D., Słowiński M., Stančikaitė M., Stivrins N., Tunno I., Veski S., Wacnik A., Masi A.
Publication: Nature Ecology & Evolution
DOI: doi.org/10.1038/s41559-021-01652-4

Provided by University of Tuscia