Oldest known plague outbreaks identified in Siberian hunter-gatherers
New research challenges the idea that plague outbreaks only emerged after the rise of agriculture and dense settlements.
- 18 June 2026
- 4 min read
- by Linda Geddes
At a glance
- An analysis of ancient DNA from Siberian hunter-gatherers suggests that plague was causing lethal outbreaks around 5,500 years ago, earlier than previously thought.
- The study suggests that early forms of the disease may have spread from person to person within family groups, rather than being transmitted by fleas.
- The findings challenge the idea that plague epidemics only emerged after the rise of agriculture and large settlements.
Few diseases have shaped human history as profoundly as plague. Responsible for some of the deadliest epidemics ever recorded, it has long been associated with cities, trade routes and dense human populations. But a new study suggests the disease was causing lethal outbreaks among hunter-gatherers in Siberia around 5,500 years ago, challenging the idea that epidemics only emerged after the rise of agriculture and large settlements.
How long have human societies been affected by plague?
For centuries, the only records of human plague were historical accounts of pandemics such as the Black Death, which killed tens of millions of people in medieval Europe. But recent advances in ancient DNA analysis have enabled scientists to trace the disease much further back in time.
In 2015, researchers identified the plague bacterium, Yersinia pestis, in the remains of people who lived around 5,000 years ago in Asia and Europe. Subsequent studies uncovered even earlier strains in Neolithic farmers in Scandinavia and a hunter-gatherer from Latvia who lived more than 5,000 years ago.
Yet these early strains lacked some of the genetic features seen in later plague bacteria, raising questions about whether they could have caused severe disease or major outbreaks. The new study, published in Nature, suggests they could.
The Lake Baikal region of Siberia contains some of the best-preserved evidence of prehistoric hunter-gatherer life anywhere in the world, including numerous burial sites that were used over many generations. Among them, one cemetery known as Ust’-Ida I had long stood out. It contained an unusually high proportion of child and adolescent remains, while radiocarbon dating suggested that many of the burials had occurred within a surprisingly brief period.
“It was a complete mystery as to why all these people were dying at the same time in this very tragic way,” said Ruairidh Macleod at the University of Oxford, who led the research.
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To investigate, Macleod and his colleagues analysed ancient DNA from 46 individuals buried at four hunter-gatherer cemeteries around Lake Baikal. They found traces of Y. pestis in 18 of them, at higher levels than any other pathogen. By combining this evidence with radiocarbon dates, family relationships reconstructed from DNA and the age profiles of those who died, the researchers concluded that the communities had experienced at least two plague outbreaks several centuries apart, beginning around 5,500 years ago.
“It was a complete surprise that we discovered this really early evidence for large-scale lethal outbreaks of plague amongst these hunter-gatherer communities at this point in time,” Macleod said.
How do these findings change our understanding of plague’s origins?
The newly discovered strain appears to represent one of the earliest chapters in plague’s evolutionary history. Scientists believe plague evolved from a close relative called Yersinia pseudotuberculosis, a bacterium that still causes gastrointestinal illness in animals and humans today. Genetic analysis suggests the Siberian strain belongs to one of the earliest known branches of the plague lineage, offering a rare window into what plague may have looked like shortly after it first emerged.
“Our findings suggest that plague originated among hunter-gatherers in Central Asia, and that the early plague was deadly, something that has been hotly debated,” said Prof Eske Willerslev at the Universities of Copenhagen and Cambridge, the study’s senior author.
Like other ancient strains found in Latvia and Scandinavia, the Siberian strain lacked key genetic adaptations required for efficient flea-borne transmission. This suggests it spread differently from the forms of plague responsible for later pandemics, possibly through close human contact after initially spilling over from wild rodents.
Supporting this idea, genetic analysis of the relationships between the skeletons suggested that small family groups were affected by the outbreaks. “We find evidence that this plague was lethal, and especially killing children and young people, and spreading among family members,” said Willerslev, “possibly spreading as they cared for each other and moved around.”
If correct, the findings suggest that devastating epidemics were affecting human communities long before the emergence of cities and large-scale agriculture. “Plague outbreaks causing mass mortality were likely prominent among hunter-gatherers, questioning arguments that outbreaks were only restricted to later more population-dense societies,” Willerslev said.
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