Tuesday, August 3

5,000-year-old hunter-gatherer is the first person to die from the plague | Sciences


A hunter-gatherer who lived more than 5,000 years ago is the first known person to die from the plague, the researchers revealed.

Stone age communities in Western Europe experienced a huge population decline around 5,500 years ago, an event that is believed to have subsequently enabled a large migration of people from the East.

The plague has been postulated as an explanation after it was previously found in Stone Age individuals, including a 20-year-old woman from a rural farming community in Sweden.

However, the researchers say their new discovery casts doubt on the idea suggesting that the nature of the strain found in hunter-gatherers likely would not have caused rapid spread.

“We believe that these first forms of Y. pestis It really couldn’t cause large outbreaks, ”said Professor Ben Krause-Kyora, a co-author of the study at Christian-Albrecht University in Kiel, Germany.

Writing in the journal Cell Reports, Krause-Kyora and her colleagues describe how they analyzed ancient DNA recovered from the teeth and skull bones of four individuals buried in a prehistoric dump, or shell dump, at a site in Latva called Riņņukalns.

The remains, which date to between 5,300 and 5,050 years ago, were of a young woman, a baby and two men, and were unearthed in two excavations, one in the 19th century and another a few years ago.

This image shows the jaw of the man who was buried in Rinnukalns, Latvia, about 5,000 years ago.
This image shows the jaw of the man who was buried in Rinnukalns, Latvia, about 5,000 years ago. Photography: Dominik Göldner, BGAEU, Berlin

The team examined the genetic material for signs of known pathogens, including Y. pestis – the bacterium that causes the plague, revealing that one of the men, aged between 20 and 30, had not only DNA fragments, but also proteins, indicating that he had died with a now-extinct form of the plague in his stream blood.

“Up to date [it is], the oldest known plague victim, ”Krause-Kyora said.

Further analysis revealed that the strain probably separated from all other forms of Y. pestis about 7,200 years ago, making it the oldest known strain of the plague, and it was distinctly different from those found later in the Neolithic and Bronze Age.

The researchers added that the strain lacked the gene that allowed fleas to spread plague.

“The flea appears to be one of the main vectors that is driving really rapid distribution and rapid infection during the Middle Ages,” Krause-Kyora said, adding that black buboes, caused by infected lymph nodes, are associated with this propagation path.

Instead, the team says the man could have had a septicemic plague, a blood infection, caused by a rodent bite or pneumonic plague, which affects the lungs and is transmitted by droplets. While the latter is typically more virulent than bubonic plague, the team says the genetics of the former strain suggest that its ability to spread may have been compromised.

The researchers also said they found high levels of Y. pestis DNA in stone age man, suggesting that he may have lived with the plague for some time and thus the disease may have been mild.

Krause-Kyora said the results – together evidence of Y. pestis In ancient populations beyond Western Europe, the rarity of Stone Age plague pits and the careful burial of man in Latvia suggested that the plague was unlikely to be to blame for the age-of-age population decline. stone. Instead, he endorsed the idea that factors such as climate change played a role.

The site of Rinnukalns, a Stone Age shell dump on the banks of the Salaca River near the mouth of Lake Burtniek.
The site of Rinnukalns, a Stone Age shell dump on the banks of the Salaca River near the mouth of Lake Burtniek. Photographer: Harald Lübke, ZBSA, Schloss Gottorf

Professor Simon Rasmussen of the University of Copenhagen, a co-author of the research on the Swedish victim of the Stone Age plague, welcomed the new study, but said he did not rule out the possibility that the plague had caused a dramatic decline. in the stone age population, adding that there was little evidence that stone age strains caused only mild disease.

In fact, the individual overlaps with Neolithic decline and most likely died from the plague, ”he said.

“We know that large settlement, trade and movement occurred in this period, so human interaction remains a very plausible cause of the spread of plague in Europe at this time.”


www.theguardian.com

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