Ancient killer revealed: Oldest plague epidemic hit humans 5,500 years ago

A genetic discovery is set to change humanity's understanding of when one of the most feared diseases first emerged and started affecting humans.

In Short

• Oldest plague outbreak found in Siberia, 5,500 years ago
• Plague affected hunter-gatherer groups, not just settled farmers
• 18 of 46 ancient remains showed plague infection, including many children

Plagues have been killing humans for almost as long as humans learnt to live. Or has it been doing it even longer?

A plague outbreak that struck hunter-gatherer communities in Siberia has been identified as the oldest known epidemic caused by the plague bacterium, according to a new study published in Nature.

The plague has been found to have killed humans almost 5,500 years ago.

It's a serious infectious disease caused by the bacterium Yersinia pestis and historically has been responsible for some of the world's deadliest pandemics, including the Black Death in the 14th century, and is typically spread by fleas carried by infected rodents, though some forms can also spread between people.

The discovery of the oldest plague has pushed back the confirmed history of plague by around 200 years and offers fresh insights into how one of humanity's deadliest diseases first emerged and spread.

Researchers analysed ancient DNA from 46 human remains recovered from four burial sites near Lake Baikal in southeastern Siberia, detecting traces of the infection in 18 individuals. Many of them were children and adolescents.

ANCIENT AND DEADLY

The findings challenge the long-standing belief that large-scale plague outbreaks only became possible after humans adopted agriculture and began living in densely populated settlements.

Instead, the evidence suggests that the disease was already capable of causing deadly epidemics among relatively small hunter-gatherer communities.

Scientists were particularly surprised by the high number of infected individuals found at the burial sites, indicating the outbreak may have had a devastating impact on local populations.

The study also revealed that children appeared especially vulnerable to the disease. Researchers linked this to genetic traits present in the ancient strain of the bacterium that may have triggered severe immune responses in younger people.

EARLY EVOLUTION OF THE PLAGUE

The newly identified strains represent some of the earliest known forms of Yersinia pestis.

Researchers said the bacterium had already evolved the ability to cause serious illness but had not yet acquired some of the genetic adaptations that later enabled plague to spread efficiently through fleas carried by rodents.

Scientists believe the pathogen may have originated in marmots, large rodents that were commonly hunted in the region.

The disease then likely jumped from animals to humans before spreading between people, possibly through respiratory transmission.

The new findings suggest humanity's encounter with the disease began thousands of years earlier than previously confirmed, providing a rare glimpse into the origins and evolution of a pathogen that has shaped human history for millennia.

- Ends