New research suggests the bubonic plague was a deadly threat around 5,500 years ago, wiping out entire families within mobile hunter-gatherer groups long before farming and crowded cities became common.
An international team analyzed ancient DNA from human remains at four burial sites near Lake Baikal in East Siberia. By extracting genetic material from teeth, scientists reconstructed early bacterial genomes, uncovering previously unknown forms of the plague bacterium, Yersinia pestis.
"Our findings demonstrate that these ancient strains were already highly lethal," stated senior author Eske Willerslev, a professor at the University of Copenhagen and University of Cambridge. The research combined genetic evidence with archaeology and radiocarbon dating to paint a detailed picture of prehistoric outbreaks.
The DNA of Yersinia pestis was found in nearly 40% of the 46 individuals tested, a higher detection rate than seen in some medieval plague burial sites. This challenges the previous assumption that early plague strains, lacking features for efficient flea transmission, were less severe.
Archaeologists were puzzled for decades by the unusually high number of children and young teenagers buried together at the largest cemeteries over short periods. The new findings suggest plague was the cause, with evidence pointing to siblings and parents dying together during the same outbreaks.
The ancient plague strains also contained a unique superantigen, a toxin that can trigger an extreme immune response, potentially making infections far more dangerous. This suggests early plague was capable of causing deadly epidemics even before evolving efficient flea-based transmission, and may have originated in Central or North-East Asia before spreading via wild rodents like marmots.
