Photo: Mateusz Klimek/ Jarosław Puszko
Researchers have uncovered the oldest known evidence of plague infecting humans, identifying the bacterium Yersinia pestis in the remains of Stone Age hunter-gatherers from Siberia dating back around 5,500 years.
The study found traces of previously unknown plague strains in 18 individuals buried near Lake Baikal. Scientists believe the disease was most likely a form of pneumonic plague that spread from wild marmots to human communities living around the lake.
Genetic analysis revealed a unique immune-triggering gene in the ancient strains, which may explain why many of the victims were children. Several infected family members were buried together, suggesting deadly outbreaks swept through closely related groups.
The discovery challenges the long-held theory that large-scale epidemics only emerged after the rise of farming societies. Researchers say the findings provide some of the strongest evidence yet that highly lethal plague outbreaks affected prehistoric hunter-gatherer populations.
The team identified two separate outbreaks between roughly 5,600–5,300 years ago and 5,100–4,900 years ago. Scientists hope further DNA sequencing will reveal whether the victims died during the same epidemics or from multiple independent infections.
The findings also add to growing evidence about the deep history of plague, one of humanity’s deadliest diseases, whose later descendants would eventually cause the devastating Black Death.
