New research indicates that the plague, a disease typically linked to medieval outbreaks like the Black Death, was a significant killer of hunter-gatherer societies as far back as 5,500 years ago. This finding challenges long-held assumptions about the health and lifestyle of prehistoric human communities.
Ancient Burials Reveal Devastating Outbreaks
Archaeological investigations near Lake Baikal in Siberia have uncovered burial sites with a perplexing mortality pattern. Many individuals, including a notable number of children and adolescents, appear to have died within a short timeframe. Initial examinations of the skeletons revealed no signs of violence or trauma, leaving researchers without a clear explanation for these catastrophic events.
A team of scientists analyzed ancient DNA extracted from 46 individuals across four sites in the region. Their findings revealed the presence of Yersinia pestis, the bacterium responsible for plague, in 18 of the samples. This represents nearly 40% of the individuals tested, a rate higher than observed in some medieval mass graves where plague was known to be rampant.
Ruairidh Macleod, a researcher involved in the study, stated that the results are “consistent with pretty much everybody having died of plague” across two distinct outbreaks. The earliest of these outbreaks dates back 5,500 years, a discovery that came as a “complete surprise” to the research team.
Rethinking Prehistoric Life and Disease
Previously, the oldest known evidence of plague dated back to farming communities in northern Europe approximately 5,300 years ago. The virulence of these ancient plague strains had been a subject of ongoing scientific debate. It was widely believed that hunter-gatherer groups, due to their small, mobile social structures, would have been less susceptible to devastating infectious disease outbreaks.
Eske Willerslev, a senior author of the study, explained that the prevailing view was that “infectious disease can’t really take a hold and devastate entire communities” among nomadic peoples. This perception contributed to popular scientific narratives that portrayed the hunter-gatherer era as a “kind of golden age” free from widespread illness.
However, the new findings suggest a different reality. “Well, it wasn’t that easy to be a hunter-gatherer,” Willerslev commented, noting that plague now appears to have been “very common” among these ancient populations.
The Role of the Tarbagan Marmot
While rats are famously associated with plague transmission in the Middle Ages, evidence suggests that the Tarbagan marmot may have been the primary vector for these prehistoric Siberian outbreaks. Macleod explained that marmots are believed to be the original host species for plague. Even today, cases of plague transmitted by marmots are documented in regions like Siberia and Mongolia, where these rodents are hunted for their pelts and meat.
It is theorized that hunter-gatherers likely contracted the plague through direct contact with infected animals. “Presumably the first infection was from an animal interaction and then spread among humans” through respiratory droplets, said study co-author Astrid Iversen, a virology professor. This aligns with modern understanding, where the World Health Organization estimates that three-quarters of new infectious diseases originate from animal-to-human transmission.
Lessons for the Present
The study of these ancient plague outbreaks offers valuable insights for contemporary public health. Understanding how diseases jump from animals to humans and how they evolve across different times and locations is crucial for mitigating future pandemic risks. Macleod emphasized the importance of “understanding the risk of that happening in the future” by examining these historical zoonotic events.
