The black death never really left, ancient DNA from 11 sites shows

Fahad Redha

September 22, 2026
5 min read

The black death never really left, ancient DNA from 11 sites shows

The Black Death is usually told as a single catastrophe: five or six years in the mid-fourteenth century, tens of millions dead, and then, in the popular imagination, Europe slowly recovers. That version leaves out roughly four hundred years of the disease’s actual behaviour, and a new genetic study led by the University of Tartu has just filled in a large part of what happened in between.

The research team reconstructed 26 genomes of Yersinia pestis, the bacterium that causes plague, pulled from human remains at 11 archaeological sites across Estonia, Russia, England, the Netherlands, and Switzerland. The samples run from the fourteenth century through to the eighteenth, covering most of what historians call the Second Plague Pandemic, the long tail of outbreaks that followed the Black Death’s first devastating wave. The study is published in the Proceedings of the National Academy of Sciences.

What the genomes show upends the old assumption that plague simply lingered in one place and periodically flared outward. Instead, the bacterium appears to have resurfaced independently in different parts of Europe across several centuries, each time potentially seeding a fresh reservoir where it could persist among wild rodents. Estonia’s own record makes the pattern especially clear. The country was hit repeatedly, not by a single strain re-emerging, but by plague arriving anew from elsewhere multiple times across most of the Second Plague Pandemic.

One period stands out from the genetic record: 1450 to 1500, when plague lineages expanded sharply and split into three separate branches. The researchers think this split may mark the point at which the bacterium properly established itself in wild rodent populations rather than simply passing through human communities. The Great Renaissance Drought, a period of significant climatic disruption, is one candidate explanation, since modern studies of plague in living rodent populations show that climate shifts can trigger or suppress outbreaks in exactly the way that would have mattered here.

Dating ancient outbreaks this precisely has always been the hard part. During COVID-19, researchers tracking a new variant had exact collection dates attached to nearly every genome, letting them map spread almost in real time. Ancient remains rarely offer anything close to that. Radiocarbon dating alone can produce windows spanning a century or more, which makes it difficult to say whether a given sample belongs to one recorded outbreak or the next one along.

To get around that, the team built a method that narrows those broad radiocarbon windows by cross-referencing where each genome sits on the bacterium’s evolutionary tree. Applied to 64 previously published genomes alongside the 11 newly sequenced ones, it let the researchers tie ancient infections to a much tighter historical timeline than radiocarbon dating alone allows, and represents the first systematic attempt to match nearly all currently available plague genomes from this period to outbreaks that chroniclers actually recorded at the time.

That sharper dating also exposed how closely plague’s movement tracked human conflict. Newly analysed genomes strengthen the link between specific outbreaks and two of early modern Europe’s longest wars, the Thirty Years’ War of 1618 to 1648 and the Great Northern War of roughly 1700 to 1721. Armies, refugees and traders moved along the same roads, and the disease moved with them. During the 1710 siege of Tallinn, plague killed Swedish and Russian soldiers and civilians alike, one of several episodes the new genomic evidence now anchors to a specific place and date rather than a vague wartime association.

Plague’s persistence is not just a historical curiosity. The bacterium never actually disappeared, it simply stopped being a major public health threat in Europe, and it still circulates in wild rodent reservoirs in parts of the world today. Working out how it embedded itself after the Black Death, held on for four centuries, then faded from European life gives researchers a rare long-run case study in how an infectious disease establishes itself, persists, and eventually recedes, knowledge the team says could sharpen surveillance of the regions where plague still exists.

The England samples in this new dataset come from Cambridge, drawn from the All Saints by the Castle site and from Clopton in Cambridgeshire, with researchers at the University of Cambridge among the study’s collaborators. That English strand connects to a longer line of plague genome research this new paper builds on, including earlier work that placed Cambridge burials alongside genomes recovered from London’s East Smithfield Black Death cemetery, excavated by the Museum of London Archaeology. The picture assembled across those studies is of a single fourteenth-century strain that reached England, France, Germany, Italy, Spain and Norway in near-identical form during the initial Black Death, before diverging into the multiple branches this latest research now traces across the following four centuries.

Taken together, the study’s authors describe it as the most comprehensive genetic picture of the Second Plague Pandemic assembled to date, built from ancient DNA, archaeology, historical chronicles and radiocarbon dating combined. It replaces the single-disaster version of the Black Death with something closer to what the documentary record always implied: a disease that kept crossing borders, kept mutating into new lineages, and kept finding new places to wait.

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