After decades of speculation, scientists have finally uncovered the reason behind the mass burial of dead children by hunter-gatherers in Russia 5,500 years ago. It appears that these children fell victim to an ancient plague outbreak caused by Yersinia pestis, the same bacteria responsible for the infamous Black Death in the 14th century, as detailed in a recent study published in Nature by an international team that includes Canadian researchers.
The study reveals that the plague was already lethal to humans millennia before the medieval pandemic, and it had the ability to spread among hunter-gatherer communities, not just in later densely populated settlements.
“The early evidence of widespread fatal plague outbreaks among these hunter-gatherer groups was a complete surprise,” said lead author Ruairidh Macleod, a postdoctoral researcher at Oxford University, during a news briefing on the findings.
Unraveling the Mystery
For years, Andrzej Weber, an anthropology professor at the University of Alberta, and Angela Lieverse, an archaeology professor at the University of Saskatchewan, have been studying the remains of a prehistoric hunter-gatherer society near Lake Baikal in Russia. Weber leads the Baikal Archaeology Project, which has been ongoing for four decades, shedding light on the ancient way of life in this region.
Two decades ago, Weber and Lieverse noticed a peculiar pattern in the burials at one archaeological site – a significant number of children under 12 years old were interred. This raised questions as to why so many children were buried, a phenomenon uncommon in the area.
Lieverse, specializing in the study of human bones, meticulously analyzed the skeletal remains to determine age and sex, looking for signs of diseases. However, only chronic conditions like malnutrition, tuberculosis, or cancer leave traces in bones, while infectious diseases have a swift impact.
The research team, including ancient DNA expert Macleod, discovered the plague bacteria during their investigation. This finding shed light on the mystery surrounding the unusual burial pattern.
The plague, still prevalent in the region today, is known to be transmitted by marmots, large rodents consumed by the hunter-gatherers and sometimes buried with ornamental items made from marmot teeth.
Deadly Strain Affecting Children
One intriguing aspect was the potency of this plague strain, particularly its devastating impact on children. Genetic analysis revealed the presence of a “superantigen” capable of causing severe inflammatory complications resembling Kawasaki syndrome, especially in children due to their distinct immune systems.
Interestingly, this strain lacked the genes necessary for bubonic plague transmission through fleas.
Prior to this discovery, the earliest known plague strain dated back 5,200 years, lacking the means for efficient flea and rodent transmission, leading many to believe it would not cause significant outbreaks.
The Lake Baikal outbreak affected multiple family groups, suggesting person-to-person transmission. In a poignant instance, DNA analysis revealed that three young girls aged seven to nine, who were sisters and cousins, died simultaneously.
According to Macleod, the outbreak had a devastating impact on the children in these communities.
Understanding how lethal pathogens like the plague evolved over