This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: The Black Death is often remembered as a single catastrophic event that swept across Europe between 1347 and 1353, killing millions. Yet the disease did not disappear after that first devastating outbreak.
For more than four centuries, plague continued to return in recurring waves, reshaping communities, economies and societies across Europe and beyond. A new study led by researchers at the University of Tartu sheds fresh light on this long and complex history by analyzing the DNA of the plague bacterium preserved in archaeological human remains. The study is published in the journal Proceedings of the National Academy of Sciences.
The researchers reconstructed 26 genomes of Yersinia pestis, the bacterium responsible for plague, from 11 archaeological sites in Estonia, Russia, England, the Netherlands and Switzerland. The samples span a period from the 14th to the 18th centuries, covering much of the so-called Second Plague Pandemic. The results reveal the complex history of plague with unprecedented resolution.
Rather than persisting in a single location after the Black Death, plague repeatedly resurfaced in different parts of Europe over several centuries, seeding multiple new reservoirs. The researchers found evidence that plague was introduced multiple times into Estonia throughout much of the Second Plague Pandemic, showing that close connections with other parts of Europe also facilitated the spread of disease. One of the study's most notable findings was evidence of a major expansion of plague lineages around 1450–1500.
During this period, the bacterium diversified into three major branches that may have established new reservoirs in wild rodent populations. The researchers speculate that climatic changes could have played a role. One possible factor is the Great Renaissance Drought.
Modern studies have shown that climate strongly influences plague outbreaks among wild rodents, which serve as natural reservoirs of the disease. "We found evidence for repeated introductions of plague into Estonia as early as the late 14th century and identified several previously unknown genetic lineages, both in urban and rural settings," said senior author Prof. One of the most innovative aspects of the study was a new method for assigning historical plague outbreaks to recovered plague genomes.
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