Scientists have uncovered the oldest known evidence of the plague, dating back almost 5,500 years. This discovery predates previous estimates by about 200 years. The plague has afflicted humans for millennia, significantly reducing Europe’s population in the 14th century during the Black Death. Though rare, the disease persists today and can be treated with antibiotics.
Eske Willerslev, an evolutionary geneticist at the University of Copenhagen, emphasized the importance of understanding plague history to comprehend our own history. Willerslev and fellow researchers examined traces of plague-causing bacteria in four cemeteries near Lake Baikal, Siberia. They found plague DNA in the teeth of 18 ancient hunter-gatherers. Carbon dating of the bones showed that the plague triggered two outbreaks, with the first cases detected around 5,500 years ago.
The research team discovered that prehistoric plague evolved in stages and infected multiple small families. It likely spread through marmots, large native rodents, when people consumed their raw organs or handled infected skins during butchering. The disease also transmitted between individuals through coughing and sneezing.
Many of the deceased were children aged 8 to 11. Three girls were buried side by side, with two likely being cousins. The study, published in the journal Nature, reported finding an aunt and her nephew together, while her niece was buried in a separate mass grave. Ruairidh Macleod, a co-author studying ancient DNA at the University of Oxford, noted the human element in the research, highlighting that ‘people buried the dead knowing who they were in life.’ Researchers indicated that children might have been at higher risk due to weaker immune systems.
The presence of multiple victims suggests that prehistoric plague could cause both individual cases and outbreaks, said geneticist Aida Andrades Valtueña from the Max Planck Institute for Evolutionary Anthropology. Andrades Valtueña was not involved in the study.
Researchers found that this type of ancient plague evolved long before the bubonic plague responsible for the medieval Black Death. However, evidence shows that earlier plagues could be equally deadly, affecting not only crowded cities but also small nomadic groups of hunter-gatherers.
Andrades Valtueña noted via email that understanding these ancient steps can provide clues about how deadly pathogens may emerge in the future.
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