December 5, 2024

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The plague may have wiped out most of the population of northern Europe 5,000 years ago.

The plague may have wiped out most of the population of northern Europe 5,000 years ago.

DNA evidence from graves in Sweden and Denmark suggests that a plague outbreak was responsible for the demise of Neolithic culture in northern Europe.

The Neolithic culture in Europe, which produced great structures like Stonehenge, declined about 5,400 years ago. Now scientists have the best evidence yet that this was due to plague.

Ancient DNA analysis of 108 individuals living in northern Europe at the time showed that plague bacteria were present. Yersinia pestis He was present in 18 of them when they died. “We think the plague killed them,” says the geneticist. Frederick Seesholm From the University of Copenhagen in Denmark. He and his colleagues published the discovery in the scientific journal nature.

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puzzle

About 5,400 years ago, the population of Europe declined sharply, especially in the northern regions. Why this happened has long been a mystery.

Over the past decade, studies of ancient human DNA have shown that the local Neolithic population never fully recovered from this blow. Instead, they were largely replaced by other peoples from the Eurasian steppe. In Britain, for example, by about 4,000 years ago, less than 10 percent of the population came from the people who built Stonehenge.

These studies also revealed several instances of plague bacteria spreading. This suggests a possible explanation: the plague could have decimated the population of Europe, allowing the steppe peoples to settle without much resistance.

No fleas

But not everyone agreed. The biochemist and archaeologist said that occasional outbreaks of plague were to be expected, and were not evidence of a major pandemic. Ben Krause Quora From Kiel University in Germany in 2021.

He added that it is also unlikely that early forms of the bacteria caused a pandemic. Krauss Cura. The DNA of the bacteria showed that early on. Y. PestisThe variant cannot live in fleas. Bites from infected fleas are the main way people get plague.

Digging graves

Seersholm and his colleagues searched for more evidence of a prehistoric plague pandemic. The 108 people whose DNA the team was able to sequence were buried in nine graves in Sweden and Denmark. Most died between 5,200 and 4,900 years ago. They represent multiple generations of four families.

There appear to have been three different outbreaks of plague during these generations. The last outbreak was caused by a strain of bacteria with rearranged genes, which may have been more virulent.

“This happens in many individuals,” says Seersholm. “It’s the same version, which is exactly what you would expect when something spreads very quickly.”

very sick

Plague DNA was found mainly in teeth. This suggests that the bacteria entered the bloodstream and made people very sick, and was likely the cause of death, says Seersholm. In some cases, people in close contact with the bacteria were also infected, suggesting that the disease was spreading from person to person. The team suggests this could be a result of plague bacteria infecting the lungs and spreading via droplets, a form of the disease known as pneumonic plague.

Recent studies suggest that human lice can cause bubonic plague, not just fleas. This means that plague bacteria could be spread this way.

abandoned graves

“It’s good to see that all these people were buried properly,” said Seersholm. This suggests that society had not yet collapsed at that time. “If there was an epidemic, we are only seeing the beginning of it.”

After about 4,900 years ago, the cemetery appears to have been abandoned for centuries. Most of the deceased were buried there between 4,100 and 3,000 years ago, but ten individuals arrived at the grave later. These individuals were of steppe origin. They were not grave owners.

“It’s a 100 percent complete replacement,” says Seersholm. “Five thousand years ago, these Neolithic people disappeared. Now we show that plague was widespread at exactly the same time.

The researchers don’t claim their findings are the final word, but they do bolster the claim that plague caused the Neolithic decline, says Seersholm. “I would say we’ve definitely proven that.” [de pest] It had the ability to spread among people, and for example, kill an entire family.

More evidence

Krauss-Kiura acknowledges that the results show that plague was common in this particular place and time. “Our previous statement needs a slight revision. We cannot speak only of isolated cases.”

But he says there is no evidence of a higher prevalence of the disease in other areas. He believes natural burials show there was no deadly epidemic. “The findings could even suggest that YersiniaThe infection over a long period of time was more than just a chronic disease.

Seersholm and his team are now looking for more evidence elsewhere in Europe. But the only way to know how deadly the rearranged strain of bacteria is to revive it, he says. That’s a very risky approach.

“I think this paper will convince many colleagues who were skeptical of our previous work,” paleontologist Nicolas Rascovan From the Pasteur Institute in Paris, whose team suggested in 2018 that plague was responsible for the decline of the Neolithic. They then based their findings on two individuals from that period in whom plague bacteria were found.

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