Plague Devastated Families Thousands of Years Before the Black Death

However, a recent study published in Nature suggests that the disease was a deadly threat as far back as 5,500 years ago. At that time, small, mobile hunter-gatherer groups were already facing the lethal effects of the plague, long before the rise of agriculture and urban living.

Uncovering Early Plagues through Ancient DNA

An international team of researchers analyzed ancient DNA extracted from human remains found at four burial sites in the Lake Baikal region of eastern Siberia. By sequencing the genetic material preserved in teeth, scientists were able to reconstruct the genome of an ancient bacterium and identify a previously unknown form of early plague.

“The debate over whether early forms of plague were less or more lethal is ongoing, but our findings indicate that these ancient strains were highly deadly,” said lead author Eske Willerslev from the University of Copenhagen and the University of Cambridge.

To gain insights into the dynamics of these prehistoric communities, researchers combined genetic evidence with archeological findings and radiocarbon dating.

“By analyzing plague DNA, genetic relationships among victims, archaeological evidence, and radiocarbon dates, we have constructed a comprehensive picture of the epidemics that occurred during that time,” explained lead author Ruairidh MacLeod, a researcher at the University of Oxford.

Analysis of the plague bacterium DNA revealed that 18 out of 46 individuals tested were infected. This meant that nearly 40% of the subjects had evidence of the plague, a detection rate higher than that observed in some medieval plague burial sites.

Prehistoric Plagues Might Have Been More Lethal Than Expected

Earlier research suggested that ancient strains of the plague bacterium lacked certain genetic traits necessary for efficient transmission through flea and rodent hosts, leading scientists to believe that these early bacteria were not capable of causing severe outbreaks.

New findings challenge this notion.

Researchers found a high number of children and teenagers among the deceased at the two main burial sites. Archaeologists have long been puzzled by the large number of young individuals buried within a short time frame.

“The high number of children’s remains poses a mystery that we have been trying to solve since the 1990s,” said Andrei Weber from the University of Alberta, the lead archaeologist on the Baikal Archeology Project.

Radiocarbon dating revealed that many deaths occurred simultaneously. Some graves suggest that siblings perished together, while in others, it seems that parents and children succumbed to the same epidemic.

A Potential Clue to the Lethality of Early Plague Strains

Ancient plague strains contained unique superantigens, genetic elements that produce toxins not found in historical plague strains. Superantigens can trigger an exaggerated immune response, leading to severe inflammation and potentially increasing the severity of infections.

“This discovery alters our understanding of early plague outbreaks. Even before the bacterium evolved efficient flea-borne transmission, the ancient strains seem to have possessed a combination of potent virulence factors that could make the infection highly lethal,” stated lead author Martin Sikora, an associate professor at the University of Copenhagen.

Collectively, the evidence suggests that some of the earliest recorded plague outbreaks might have been as deadly as later historical epidemics, particularly for children. This high lethality may have been possible even before the bacterium achieved the efficient flea transmission associated with bubonic plague.

Did Plague Spread from Marmots to Humans?

The discovery also supports the idea that plague might have originated in Central or Northeast Asia before spreading across Eurasia via wild rodent populations.

Archaeological evidence indicates that hunter-gatherers living near Lake Baikal had interactions with marmots, large burrowing rodents that still carry diseases today. Researchers hypothesize that some of these prehistoric epidemics could have begun with the direct transmission of the disease from infected marmots to humans.

If this theory holds, plague could have caused deadly outbreaks among small human communities thousands of years before the rise of cities, crowded settlements, and flea-borne epidemics that later made the disease notorious.