The tomb where the remains of a 20-year-old neolithic woman were found. Image: Karl-Goran Sjogren / University of Gothenburg Long…
The tomb where the remains of a 20-year-old neolithic woman were found. Image: Karl-Goran Sjogren / University of Gothenburg
Long before the two deadliest pandemics in history – Justinian plague and black plague – An old strain of the bacterium responsible for these plagues, Yersinia pestis ] may have caused devastation among neolithic European societies more than 5,000 years ago, according to a controversial new study.
New research published today in Cell describes a newly identified strain of Yersinia pestis the bacterium that causes plague. DNA of the new strain was extracted from a woman living in a Neolithic farm about 4 900 years ago in what is now Sweden. The bacterium is unique because it is the oldest genome of Y. pestis ever discovered and at a genetic level it is the earliest plagiarism ever discovered.
More controversial, the authors of the new study, led by the meta-transformer Simon Rasmussen from the Technical University of Denmark and the University of Denmark Copenhagen, say that this bacterium may have spread around the late Neolithic European societies, creating plaguing conditions that contributed to the decline in these settlements and set the stage for the subsequent Bronze Age. In addition, the plague was not introduced by settlers from the Eurasian steppe, but the researchers argued, but instead had an Eastern European origin. Other experts are not convinced, but say that archaeological and genetic evidence is needed to support the claim.
Yersinia pestis The bacterium responsible for the plague. Image: Rocky Mountain Labs
At the heart of this study, Yersinia pestis is the bacterium responsible for an unjustified amount of human suffering. This pathogen, spreading to humans through bites of infected fleas, caused the Justinian plague during the sixth century, killing between 30 million and 50 million people – almost half of the human population at the time. The plague would return 800 years later and manifested itself as the black death – a threat that killed 50 million Europeans from 1347 to 1351.
However, long before these episodes, the bacterium had already made its mark on human societies. In 2015, a research group led by Rasmussen plunged back to the Bronze Age, between 3000 and 1000 BC. Rasmussen’s latest work now takes care of the pest’s origins even further to the senneolithic.
Rasmussen and his colleagues discovered the ancient strain in a publicly available database of old DNA taken from the teeth of individuals buried in Sweden’s Fralsegarden graveyard. Meanwhile for screening for specific sequences of the bacterium, the researchers stumbled upon the previously unidentified strain of the genetic material of a 20 year old woman who died in Sweden between 5,040 and 4.867 years ago. The Gok2 strain, as it is now called, was compared to bacteria that came before and after revealing minor differences and some distinct similarities. Gok2 is different from Y. pseudotuberculosis the impoverished species from which the plague deviates, to justify the declaration of a new bacterial species. At the same time, the newly discovered stem is very similar to the version of Y. pestis which we already know, containing genes responsible for the mortality of the modern pneumonic pest, for example (the plague manifests itself in two different forms, bubonic and pneumonic , the former is an infection of the lymphatic system and the latter is an infection in the respiratory system).
Interestingly, the researchers found traces of the Gok2 tribe of another individual buried in the same burial place, a 20-year-old man who lived at the same time as the woman. This could mean that both individuals died from the plague and that an epidemic had taken this agricultural community, scientists wonder.
The tomb where the remains of a 20 year old neolithic woman were found. Image: Karl-Goran Sjogren / University of Gothenburg
As noted, the Gok2 tribe is the oldest ever discovered, but it is also the most basic. By basal, the researchers mean that it is the closest known strain to the genetic origin Y. pestis -this is the earliest plague from a genetic perspective that occurs on a different evolutionary branch than other strains. The Gok2 tribe, as the authors say, occurred about 700 years ago, the burden that would last for the Bronze Age occurred 5,300 years ago, and the tribe still exists today arose 5.100 years ago. So at least three different versions of the plague did the rounds of Eastern and Northern Europe under late Neolithic, according to the new research, not to mention those we still do not know about.
This observation, say the researchers, can solve a persistent mystery about the decline in late neo-liberal societies. For reasons that are still unclear, neolithic settlements began – some of which contain between 10,000 and 20,000 people – disappeared about 5,500 years ago. The decline could have been caused by neolithic farmers who exploited the environment or by incoming settlers (or invaders depending on your historical conviction) who brought the plague along with them from the Eurasian Steppen.
However, the authors of the New Study say they have a better explanation: a late-neolithic plague driven by the Gok2 tribe, which originates in Eastern Europe, and not the Eurasian Steps.
“These mega settlements were the largest settlements in Europe at that time, 10 times bigger than anything else. They had people, animals and stored foods close to each other, and probably very bad sanitation. It’s the textbook’s example of what you need to develop new pathogens, says Rasmussen in a statement. “We think our data fits. If pests develop in the mega settlements, when people began to die from it, the settlements would have been abandoned and destroyed. This is exactly what was observed in these settlements after 5,500 years ago. “
Y. pestis The bacterium would also have begun migrating along all trade routes that were made possible by rail transport, which was rapidly expanded across Europe at this time, he explained. Eventually, the neolithic plague came to Sweden via these trade paths that infected Fralsegårdens farmers.
It was important that an analysis of the 20-year-old woman’s DNA showed that she was not genetically related to the Eurasian migrant migrants. An observation suggesting that the Gok2 tribe did the rounds in Europe before their arrival, and that Steppe Eurasians were not responsible for introducing the plague to Europe.
It is certainly meaningful, but more work will be required to confirm this theory. As the authors themselves acknowledge they have not identified the specific version of plague that could have terrorized mega settlements.
“We have not really found the smoke gun, but it depends in part on that we have not looked yet, “says Rasmussen. “And we would really want to do that, because if we could find plague in these settlements, there would be strong support for this theory.”
Boris Valentijn Schmid, a calculation biologist at the University of Oslo, described the new study as technically “solid”.
“This group has published [a paper] on these very early plague strains before and they have a good method of verifying if the bacterium they are looking at is really an early form of plague, rather than still the impoverished bacterial species from which the plague specified , Y. pseudotuberculosis “Schmid said to Gizmodo.
Johannes Krause, a genetician at the Max Planck Institute, did not love the new paper and said that the authors did not identify the oldest genome.
“They made a mistake in their study,” he told Gizmodo. Krause refers to a tribe that returns to the same period around 4 900 years ago – and was found among the Yamanya population (now Ukraine and parts of Russia), as described in a 2017 study, of which Krause is co-authors. Krause found it interesting that the new tribe was found in a person who does not have Steppegener, and that the tribe belongs to another branch in the evolutionary story of Y. pestis .
“Not only a new branch, but a more basic branch, closer to the original split of Y. pestis from Y. pseudotuberculosis ” clarified Schmid. “To me it’s a nice find.”
The claim that the plague originates in Eastern Europe “is very speculative and not backed up by any data,” Krause says. Schmid agreed to say “it’s so speculative that I would not add anything to it.”
But Schmid said the researchers presented an interesting new alternative – and it’s time for other archaeologists, genetics, microbiologists, and pathologists to do their part.
“Much depends on numbers – how often did people die of this early form of plague? And was it enough to affect the total number? In his previous work, Rasmussen and his colleagues found traces of the bacterium in seven of 101 samples , which is an impressive amount and only slightly less than the proportion of deaths caused by all communicable diseases today, “Schmid said.” But it is not clear to me if that percentage is sufficient to counteract population growth and cause a decline. “
It is really not enough to discover an old form of plague in two Neolithic Swedish individuals, but interesting. Ensure the explanation of a complete European epidemic during the late Neolithic. It is truly a convincing opportunity, and a consideration now worthy of future investigation.
It seems that the plague has been a pain in the human ass for a very long time.