Siberian Plague Rediscovered
Ancient DNA Reveals Plague Outbreak Devastated Siberian Hunter-Gatherers 5,500 Years Ago, Challenging Prior Views
Key Points
Researchers said the cemetery at Ust-Ida (on the bank of the Angara River, north-west of Lake Baikal) had long puzzled archaeologists because so many children were buried there; the ancient-DNA results helped explain it, with “at least two-thirds of the dead at two of the cemeteries” being under age 15.
A detailed case from the study involved a single grave containing a set of cousins/sisters aged 4 to 9: lead author Ruairidh Macleod said, “We see three very young girls, all buried at the same time… It’s clearly having a very tragic impact on the children in particular in these communities.”
The team detected plague DNA in “18 of 46 individuals, nearly 40%,” and noted that this yield was “higher than the detection rate reported from some medieval plague pits,” underscoring how clearly the ancient outbreak can be traced genetically.
Context on what plague is biologically: the bacterium Yersinia pestis can cause pneumonic or septicaemic disease depending on infection route, but it most commonly causes bubonic plague when flea bites seed lymph nodes, producing large “buboes.”
The new findings build on, but are distinct from, earlier ancient-DNA reports: NBC noted that a prior study found plague in a single hunter-gatherer in Latvia about 5,000 years ago, but “it did not find evidence of an outbreak or human-to-human transmission.”
Scientists have found the oldest known evidence of a plague outbreak in human history — and it devastated a small group of hunter-gatherers living near Siberia's Lake Baikal roughly 5,500 years ago. A study published in Nature found the plague bacterium *Yersinia pestis* in 18 of 46 ancient individuals tested, a detection rate of nearly 40% — higher than some medieval plague pits.
The findings overturn a long-held belief that major plague outbreaks required farming, cities, and dense populations. Instead, a small, mobile Stone Age community was being wiped out — especially its children — centuries before agriculture took hold in the region, according to EurekAlert.
Children Died in Clusters, Buried Side by Side
At two of the four cemeteries studied, at least two-thirds of the dead were under age 15. The site at Ust-Ida, on the Angara River northwest of Lake Baikal, had long puzzled archaeologists. Professor Angela Lieverse of the University of Saskatchewan recalled noticing the anomaly 20 years ago:
One grave told the story with brutal clarity. It held three young girls — cousins or sisters, aged 4 to 9 — buried at the same time. Lead author Ruairidh Macleod said,
Plague Spread Through Marmot Hunting, Then Person to Person
Researchers believe the outbreak started with animals. Marmots — large ground squirrels still known to carry plague in the region today — were a likely source. Hunters probably caught the infection while butchering carcasses or eating raw organs, according to The Guardian.
Once it entered the community, the disease spread between people. Family members buried together — siblings, cousins — suggest caregivers caught the infection from those they nursed. The same plague strain was found at sites 37 kilometers (23 miles) apart, pointing to community-to-community transmission, Live Science reported.
This Strain Was Lethal Before Fleas Were Even Involved
Modern bubonic plague spreads through flea bites, which seed bacteria into lymph nodes and cause the swollen lumps called buboes. But this ancient strain lacked the gene — called *ymt* — that lets *Y. pestis* survive inside a flea's gut. It could not yet use fleas as carriers, EurekAlert noted.
That actually made it more dangerous in some ways. Without flea transmission, the disease likely spread through direct contact or inhalation — the pneumonic and septicemic forms of plague, which kill faster than the bubonic form. Senior author Professor Eske Willerslev of Cambridge said:
Two Outbreak Waves Struck Centuries Apart, Rewriting Epidemic History
Radiocarbon dating found two distinct waves of infection. The first hit between roughly 5,520 and 5,265 years ago. A second wave followed, spanning from about 5,315 to 4,235 years ago, according to Live Science. Together, they show the disease persisted or returned to the region over several centuries.
Before this study, the oldest outbreak evidence came from a mass grave in Sweden around 4,900 years ago. A single plague-infected individual from Latvia dated to about 5,000 years ago, but CBC noted that case showed
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