The decline of the Neolithic period in Europe around 5,000 years ago was not caused by climate change or war, but by an early outbreak of plague that was not dangerous enough for humans, a new study says.

When farmers from Anatolia arrived in Europe, they brought not only genocide and new diseases, but also their way of life. The descendants of the local Mesolithic hunter-gatherers who managed to survive the arrival of the newcomers gradually accepted this and adopted agriculture.

As a result, the population density in Europe increased significantly – as can be judged by the frequency of radiocarbon-dated human burials. This happened despite the fact that the farmers’ food was qualitatively worse than that of their ancestors, the hunter-gatherers. However, the growth of the Neolithic economy in Northern Europe stopped abruptly around 5300-4900 years ago.

The decline can be judged by the sharp decline in population in those years (and the consequent discovery of human remains at that time). During this period, people stopped building megaliths and the cable pottery culture (aka battle-axe culture) spread to the north of Europe.

Various researchers have put forward hypotheses explaining the decline of the European Neolithic Age. However, none of them have been proven true. The mystery of the sudden population decline is still actively discussed in scientific circles. An international group of scientists has presented their own answer to the question of the causes of the crisis. Their work was published in the journal Nature.

The researchers examined bone remains from nine megalithic tombs in Sweden and Denmark and took DNA samples from 108 people who lived during the European Neolithic crisis. These people were mostly representatives of two genetically distinct lineages.

The first is that which resulted from the mixing of the remains of Mesolithic hunter-gatherers with Anatolian farmers. The funnel-shaped vessels belong to the archaeological culture. The second, relatively small group of people had much more DNA in their genome than the steppe natives who arrived in Scandinavia shortly before the period under study, bringing with them the wire-ware culture.

When analyzed for pathogens, 18 out of 108 people (17 percent) were found to be infected with the plague bacillus (Yersinia pestis). Before Y. pestis It has already been found in ancient burials, but nowhere is there such a high frequency of infection. The average infection rate in people of steppe ancestry was over 28 percent.

Early strains are considered accepted. Y. pestis It was not very contagious and could not cause an epidemic. They lacked a gene that encoded the protein for it. Ymt It is necessary for the reproduction of the plague bacillus in fleas, which take the causative agent of the disease from mice and transmit it to humans.

Recently, geneticists have discovered that DNA sequences Yersinia pestis partially overlaps with the genome Yersinia pseudotuberculosisthe causative agent of pseudotuberculosis. Further research showed that the plague bacillus was a mutation Y. pseudotuberculosis. And this happened not 20 thousand years ago, as previously believed, but a little less than six thousand years ago. This is shown in the work of Eske Willerslov (Eske Willerslev), one of the authors of the new study.

He and his colleagues found that at least three strains of the plague bacillus existed during the 120 years or so leading up to the Neolithic crisis. None of them had the gene responsible for the protein. YmtAt the same time, the first species was more similar than others to the ancestor, the causative agent of pseudotuberculosis, which arose before the Neolithic crisis.

Pseudotuberculosis affects humans and animals (goats, cows), and is spread by rats and mice. The main route of transmission for humans is food. The transmissibility of this pathogen is quite high: for example, in Vladivostok in 1959, the disease affected 300 people in a short time, 200 of whom had to be hospitalized.

According to the authors of the new scientific study, early Y. pestis can spread just like its ancestors. Even without fleas, humans could still transmit plague to one another through food and water.

Scientists write that 17 percent of patients is the most conservative estimate of the lower limit. Depending on the lifestyle of certain groups, the plague could affect more people. With such a level of patients, we can talk about an early outbreak of the plague, which, according to the authors of the study, was the real cause of the decline of the population in Northern Europe and the decline of the Neolithic era.