Scientists have uncovered the oldest known evidence of plague in ancient DNA recovered from graves in southeast Siberia, dating back 5,500 years. The findings, published in the journal Nature, reveal previously unknown strains of Yersinia pestis, the bacterium responsible for the plague, and suggest the disease had a devastating impact on prehistoric hunter-gatherer communities.
Core Findings and Implications
The discovery challenges long-held assumptions about the origins and spread of plague. Researchers analyzed remains from two large cemeteries in the Lake Baikal region, where an unusually high number of children and young adolescents were buried without signs of trauma. DNA analysis confirmed the presence of plague bacteria in 18 of 46 individuals, indicating at least two separate outbreaks. The study also identified a genetic factor that may have increased the severity of the infection.
Historical Context and Significance
Before this discovery, the earliest known strains of Yersinia pestis associated with bubonic plague were dated to about 3,800 years ago. Older strains were thought to lack the genetic traits necessary for widespread transmission, leading scientists to believe early plagues were unlikely to cause large outbreaks. The new findings suggest that plague may have originated earlier than previously believed and could have spread among family members within these mobile communities.
The study also highlights the tragic impact of the disease on children. One grave contained three young girls, likely cousins or sisters, who died around the same time and were buried together. The presence of plague DNA in all three individuals underscores the disease’s deadly effect on these communities.
Broader Implications for Disease History
The discovery raises questions about the origins of plague and its role in shaping human history. Plague has been responsible for some of the most devastating pandemics, including the Black Death in the 14th century, which killed an estimated 25 million people in Europe alone. Understanding how early strains of the disease spread could provide insights into its evolution and potential future outbreaks.
The findings also challenge the notion that plague primarily affected settled agricultural societies. The evidence suggests that hunter-gatherers were vulnerable to the disease, which may have spread through early livestock such as sheep and infected fleas. This discovery could reshape our understanding of how diseases transitioned from animals to humans and the role of mobility in their spread.