New Research

New Discovery That Hunter-Gatherer Children Died of Plague More Than Five Millennia Ago Sets Back the Date of the Earliest Outbreak

The skeletons of nomadic families unearthed in Siberia harbor “Yersinia pestis” bacteria, which challenges theories about conditions needed for the disease to spread

Sonja Anderson | Daily Correspondent

June 18, 2026 4:58 p.m.

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Victims of the world’s oldest known plague outbreak have been identified in Siberia. They were children of hunter-gatherers, and about 5,500 years ago, they were infected with the plague-causing bacteria Yersinia pestis while eating or skinning raw marmots.

That’s according to a study recently published in the journal Nature, for which researchers tested the DNA of 46 skeletons unearthed at four prehistoric cemeteries along the Angara River in eastern Russia, north of Mongolia. The scientists found that at least 18 of the dead had been infected with Yersinia pestis.

Lead study author Ruairidh Macleod, a genomicist at the University of Oxford, says the team didn’t expect these results. Previously, researchers assumed plagued outbreaks only happened in high-density settlements.

“Hunter-gatherers are constantly moving around the landscape,” Macleod said at a news conference, reports CNN’s Ashley Strickland. “The theory is that infectious disease can’t really take hold and devastate entire communities in this way. Typically, if somebody gets ill, they’ll move somewhere else. The fact that we’re finding this happening in an isolated group of prehistoric hunter-gatherers challenges that epidemiological theory.”

Historically, plague has been one of humanity’s most formidable enemies. It’s caused by Yersinia pestis, which lives in animals like rats and other mammals, transferred mainly by fleas. There have been three massive plague epidemics: the Plague of Justinian, which decimated the Byzantine Empire in the sixth century C.E.; the Black Death, which swept Europe in the 1300s; and the Third Plague Pandemic, which began in Hong Kong in 1894.

Until recently, the oldest scientific evidence of Yersinia pestis infection dated to 5,000 years ago: It was identified in an unearthed skeleton in Latvia in 2021. But the Siberian graves are just over 5,500 years old, according to the study.

The researchers think that these nomadic Siberians experienced two separate but overlapping plague outbreaks. Analysis of genetic material extracted from teeth revealed that the infecting strain of plague bacteria originated about two centuries before the first wave, reports CNN, and it’s different from other strains.

In particular, this early strain lacks a gene that today’s Yersinia pestis needs to survive in fleas, reports Carl Zimmer for the New York Times. Could the bacteria have jumped directly from animals to humans?

“That’s a big leap with no evidence,” David Wagner, a microbial geneticist at Northern Arizona University who wasn’t involved in the research, tells the Times. But Wagner adds that perhaps the plague originally spread directly between people.

In analyzing the victims’ DNA, the researchers discovered that the sick were closely related to each other: “Small familial groups were affected, consistent with human-to-human spread of disease,” the researchers write. Many victims were kids between 8 and 11 years old.

“A really poignant example is this grave where we see three very young girls having presumably died at the same time,” said Macleod, per CNN. “It’s clearly having a very tragic impact on the children, in particular, in the communities.” The youngest of the three girls was 4 or 5, and the oldest was 9: two sisters and their cousin.

“Previous research has only found what seem to be sporadic, relatively isolated infections of the earliest versions of Y. pestis, with no compelling evidence of human-to-human transmission chains,” Ian Light-Maka, a postdoctoral associate at the Max Planck Institute for Infection Biology who wasn’t involved in the research, tells CNN. “But the datasets may have simply been too incomplete to assess this as a possibility. This study changes that.”

The study also contradicts another previous assumption: that ancient Yersinia pestis bacteria caused only mild sickness, as it did in farmers from Neolithic Scandinavia. “It doesn’t fit the model,” study co-author Eske Willerslev, a geneticist at the University of Copenhagen, tells the Times. “But we have to accept the data.”

Nearly 40 percent of the bodies buried in these Siberian cemeteries were infected with Yersinia pestis, according to the study. The researchers have a theory about how they got it. This region near Lake Baikal is rife with marmots, large rodents belonging to the squirrel family that humans hunted for food. Within the graves, excavators found pendants made from marmot teeth. Researchers think the people unwittingly exposed themselves to Yersinia pestis that lived inside marmots.

“If you’re a prehistoric hunter-gatherer, you’re going to be in contact with a lot more wild species than an early farmer, and it’s the wild species that are primarily the reservoirs of the disease, not the domesticated animals,” MacLeod said, reports the Guardian’s Ian Sample.

These cemeteries were discovered decades ago, and they’ve mystified archaeologists since then. The new research not only sheds light on the prehistoric people’s suffering and burial practices, but on the formidable infection behind their deaths.

“The unusually high number of children and the short timespan was a real puzzle that we’ve been trying to solve since the 1990s,” says study co-author Andrzej Weber, principal investigator of the Baikal Archaeology Project, in a statement. “Finding out that plague was the cause is extraordinary, but it makes so much sense.”

Sonja Anderson | Read More

Sonja Anderson is a daily correspondent for Smithsonian magazine who covers art, archaeology and culture, from newly discovered artifacts to the latest art heists.