A German-Latvian research team has detected the oldest known plague-causing bacteria in the remains of a hunter-gatherer who lived in present-day Latvia 5,000 years ago.

According to a study published in Cell Reports, the new findings show that the bacteria that causes plague had emerged thousands of years earlier than the scientific community previously believed. So the plague has been around longer than we thought.

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The man, aged between 20 and 30, likely died after a rodent bite, the study revealed. The skull of the hunter-gatherer was excavated in the late 1800s. It re-emerged in 2011 after being lost for a century, in the collection of German anthropologist Rudolph Virchow.

Researchers studied the remains, along with three other specimens found on the same site. These remains were likely all from the same group of hunter-gatherers. The samples from their teeth and bones were used to sequence their genomes. Researchers used that to identify bacterial and viral pathogens in the remains.

Due to the remains being very old, the DNA could only be found in small fragments, the team said. They then reassembled the genome of the bacterium and analyzed and compared it with ancient and modern Y. pestis strains that cause plague.

The evidence of the plague-causing bacteria in the samples belonging to the 20 to 30-year-old was stunning.

“What’s most astonishing is that we can push back the appearance of Y. pestis 2,000 years farther than previously published studies suggested. It seems that we are really close to the origin of the bacteria,” CNN quoted the lead author of the study Ben Krause-Kyora as saying.

The fact that the bacteria were only present in the remains of just one person and not in those buried near him appeared to rule out a community spread.

There have been many outbreaks of plagues in history, most notably the deadly plague in medieval Europe that wiped out a major chunk of the continent’s population.

The study contradicts the earlier belief that Y. pestis emerged from cities that only developed long after the hunter-gatherer phase of human evolution.