The development of agriculture in Late Stone Age Europe was not a smooth transition from a hunter-gatherer lifestyle, but a bloody takeover in which settler farmers decimated the nomadic population within a few generations, a new study has found. In fact, twice in just a thousand years, the population of southern Scandinavia was replaced by aliens whose DNA profiles analyzed by an international team of researchers contained almost no trace of their ancestors.

“This transition was previously thought to be peaceful,” explains study author and paleoecologist Ann Birgit Nielsen from Lund University. “But our research suggests otherwise. In addition to violent deaths, new pathogens from livestock are likely to kill many foragers as well.”

Using a technique called shotgun sequencing, the team analyzed DNA samples from 100 human remains found in Denmark. The ruins spanned 7,300 years of the Mesolithic (or Middle Stone Age, when hunter-gatherer lifestyles began to decline), the Neolithic (or New Stone Age, when people began farming), and the Early Bronze Age.

Focusing on a specific region with a climate suitable for foraging and farming, as well as the preservation of human remains, allowed researchers to map gene flow between populations, as well as changes in vegetation that reflected how they used the land.

The analysis shows that about 5,900 years ago, a farming population displaced hunters, gatherers and fishermen who had previously lived in Scandinavia and cleared forests to make way for farmland. Previous research (by comparing the DNA of several skeletons) had shown that these early Scandinavian farmers inherited about 30 percent of their genome from hunter-gatherers; This meant that their populations mixed, not that one wiped out the other.

Instead, much archaeological evidence suggests that this was a particularly brutal period, and the new study shows that hunter-gatherer DNA was essentially wiped out, leaving little to be seen in the genomes of Scandinavia’s first farmers. However, their reign was relatively short-lived. Farmers, also known as the Voronkober culture, survived for about 1,000 more years until a new wave of newcomers arrived from the eastern steppes.

The newcomers brought with them their ancestors from the Yamnaya, a pastoral people from southern Russia. They quickly replaced the Voronkobers, creating a new cultural group called the Single Grave Culture.

“This time there was also rapid population turnover, and there were almost no descendants of their predecessors,” says Nielsen, noting that the DNA profile of the first farmers to settle in Denmark was essentially wiped out from the modern Danish population.

“We don’t have a lot of DNA material from Sweden, but we do have things that point to a similar pattern,” Nielsen adds.

Extensive archaeological evidence found before this study documented the transition from the Beaker Culture to the Single Grave Culture, but the relationship between the two groups is often debated. Now, with a better understanding of the origins of Danes and Swedes, researchers hope they can identify genetic signatures in ancient DNA that could explain modern health patterns; just as scientists have determined why multiple sclerosis is more common among white, northern Europeans. their southern counterparts.

“Our results help expand our knowledge of our heredity and the development of some diseases. Something that could be useful in the long term, for example, in medical research,” concludes Nielsen.