Plague killed 40% of hunter-gatherers 5,500 years ago
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- A Nature study detected Yersinia pestis DNA in 18 of 46 individuals (~40%) at four Lake Baikal hunter-gatherer cemeteries in East Siberia — a detection rate exceeding some medieval plague burial sites.
- Eske Willerslev, co-senior author and professor at the University of Copenhagen and Cambridge, said the 5,500-year-old strains were "highly lethal," overturning prior assumptions that early plague was a mild, pre-pandemic form of the disease.
- The ancient Y. pestis strains carried a unique superantigen toxin not found in later historic strains, which co-senior author Martin Sikora said made infections highly dangerous even before the bacterium evolved efficient flea-borne transmission.
- Lead author Ruairidh Macleod combined plague DNA, genetic relationships between victims, and radiocarbon dating to reconstruct rapid, family-based outbreaks at the Lake Baikal sites.
- Archaeological evidence at the two largest cemeteries showed siblings and parents buried together over short timespans — a pattern that had puzzled archaeologists since the 1990s and is now attributed to plague sweeping through families.
- Marmots, large burrowing rodents that still carry plague today, likely transmitted the disease directly to Baikal hunter-gatherers, supporting a Central or North-East Asian origin for the plague bacterium before it spread across Eurasia.
Why it matters: The study overturns the long-held assumption that early plague was a mild precursor to medieval killer strains, showing prehistoric hunter-gatherers — without urban density or rat populations — still suffered devastating, family-based outbreaks that disproportionately killed children. It pushes the earliest confirmed lethal plague back 5,500 years and adds support to a Central/North-East Asian origin hypothesis.
