A new discovery has pushed the chronology of pestilence back to Europe earlier than we had previously thought. A new strain of the bacterium Yersinia pestis has been identified in 4,900-year-old bones at a Neolithic burial site in Sweden.
It is the oldest ever identified and the most basic strain we have seen, that is the strain closest to the genetic origin of the bacterium.
Y. pestis has been a real scourge of humanity throughout history, repeatedly erasing large areas of the population.
He was responsible for the pestilence of Justinian who broke 541 CE, killing 25-50 million people at the end; the black plague of the 14th century, which swept away 75 to 200 million people throughout Eurasia; the Great London Plague of 1
"Plague is perhaps one of the deadliest bacteria that ever existed for human beings," said geneticist Simon Rasmussen of the Technical University of Denmark and the University of Copenhagen.
"The kind of analysis we do here makes us go back in time and look at how this pathogen that has had such a great effect on us has evolved."
The discovery of Y. pestis in the bones of a 20-year-old Neolithic woman suggests that the plague spread to Europe much earlier than previously thought, according to new research.
Just a few months ago a different team of researchers announced that they had found the oldest ever univocal proof of the plague to date – in the bones of people who lived in the Eurasian steppe 3,800 years ago.
Other research at the beginning of this year has also found a way to migrate for Justin's plague which suggested a Mongolian origin.
But if the bacteria first spread to Europe, this could help explain a mystery that has long perplexed scientists – that is, the disappearance of the first European farmers.
These were people who had emigrated from the Middle East from about 9,000 years ago, and up to 20,000 people gathered in settlements. These people – called Trypillia Cultures – developed technology, such as ceramics, the wheel and metallurgy, and kept the cattle.
But about 5,400 years ago, they simply … disappeared. Their settlements ceased to be built, and the genome had a drastic change from about 4,500 years ago, suggesting a new influx of people from the steppe, which eventually replaced the Trypillia Culture.
So what happened to the Trypillians? It is a puzzling mystery with many potential explanations that have been the subject of heated debate. Perhaps they simply assimilated themselves to other coming cultures. Perhaps they were conquered. Perhaps their resources ran out and they had to move on.
But Rasmussen and his team believe it could have been something else. The strain of Y. pestis found in Sweden diverged from the other strains about 5,700 years ago – prior to the influence of steppe populations.
Those huge Trypillian settlements, without adequate sanitation facilities, and with humans living in close relationship with animals, could have had incredible fertile grounds for pathogens. The plague could have evolved right there in those European settlements.
"We think that our data adapt: if the plague has evolved into mega-settlements, then when people started dying, the settlements would have been abandoned and destroyed", Rasmussen
"This is exactly what that was observed in these settlements after 5500 years ago: the plague would also begin to migrate along all the commercial routes made possible by wheeled transport, which had rapidly expanded throughout Europe during this period. "  And those trade routes are like the plague could have ended up in Sweden 4,900 years ago.
But at this point, these hypotheses are all but definitive, in particular because Y. pestis has not yet been identified in any Trypillian residues or settlements. This is the next step in the search.
"We did not really find the smoking gun, but partly because we have not looked at it yet," Rasmussen said. "And we would really like to do it, because if we could find the plague in those settlements, it would be a strong support for this theory."
The team's research was published in the journal Cell .