A team of scientists may have discovered the oldest human plague from the 5,000-year-old remains of a young woman in Sweden. It is possible that this plague may have wiped out the Neolithic farmers of Europe, a discovery that could change our understanding of European history.
The study suggests that a plague was spread by traders among Neolithic European settlements and wiped them out, allowing for the massive human migration from Russia and Ukraine in Europe that came afterward, overturning the European gene pool. It has previously been debated how these migrants were able to displace the Neolithic farming culture.
A plague could be the answer.
“These events had major consequences for the history of humanity,” said study lead Nicholas Rascovan, a bioinformaticist at Aix Marseille University in France.
“This is actually when the genetic makeup of the modern European is created,” added Simon Rasmussen, an evolutionary and systems biologist at University of Copenhagen, Denmark, who also played a lead role in the study.
Both scientists looked into why large, Neolithic mega-settlements of 10,000 to 20,000 people suddenly collapsed and were buried.
“These mega-settlements were the largest settlements in Europe at that time, 10 times bigger than anything else. They had people, animals, and stored food close together, and, likely, very poor sanitation. That’s the textbook example of what you need to evolve new pathogens,” Rasmussen said.
The data fits this theory, Rasmussen says: the plague evolved in these mega-settlements, and when people started dying from it, the settlements were abandoned and destroyed, which is what was observed in settlements after 5,500 years ago. The plague would have started migrating along trade routes, made possible with the advent of wheeled transport, and spread rapidly throughout Europe at that time.
DNA extracted from the woman’s teeth provides further evidence for this theory, as it shows that she isn’t genetically related to the people who later migrated to Europe from the Eurasian steppe, which supports the idea that they were wiped out before the mass migration began.
Archeology further supports this hypothesis, as there were no signs of migrants at the time when she died.
This particular strain is believed to be the oldest to be discovered. In comparison with other strains, it is the closest to its genetic origin, Yersinia pestis, the bacteria that causes plague, which means that it likely diverged from that strain around 5,700 years ago, and suggests that there were multiple strains of plague by the end of the Neolithic period.
The scientists also compared DNA sequences of this newfound strain to other known strains today. It was found not to be related to the bubonic plague, an epidemic that killed 30 to 60 percent of Europe’s population in the mid-1300s, but was found to be related to the even more deadly pneumonic plague, which spread through flea-carrying rodents. This plague infects the lungs and can spread from person to person through saliva droplets.
However, the team’s findings are still confirmed, as other remains from the mega settlements have yet to be studied.
“We haven’t really found the smoking gun, but it’s partly because we haven’t looked yet. And we’d really like to do that, because if we could find plague in those settlements, that would be strong support for this theory,” Rasmussen said.
If this theory is correct, Rascovan adds, it will have a huge impact, as it will show how a single bacteria can have an great effect on history’s unfolding.