Agriculture developed in the Middle East about 11,000 years ago. People no longer roamed in search of food, but became self-sufficient and settled. It was not until five thousand years later that the agricultural revolution reached Northern Europe. How the Northern Europeans became farmers has been the subject of debate for over a hundred years. Swedish and Danish researchers think they have found the answer.
About 5,000 years ago, Swedes living on Gotland Island buried their dead in large collective graves according to traditions of the Pitta-Ware culture, a hunter-gatherer culture in Europe. In one of those graves they buried a 7-year-old child, a woman of about 45 years and a man of about 25.
Around the same time, farmers 400 kilometers away on the mainland in Gökhem buried a 20-year-old girl in a megalith that we know in the Netherlands as a dolmen. Danish and Swedish researchers from the University of Copenhagen and Uppsala University used the DNA of these four dead to find out how agriculture spread across Europe.
Scientists previously discovered that agriculture reached Europe from the South East about 8400 years ago. It then took almost 2400 years before people in Northern Europe also opted for a farming existence. The hunter-gatherers and farmers lived side by side for about 1000 years afterwards.
But many questions remained; how did agriculture reach Europe? Did the farmers themselves migrate from the Middle East and teach northerners their way of working? Or were only the ideas spread? Which route did the farmers take and how did they replace the hunter-gatherers who already lived in Europe? The research by the Danish and Swedish researchers provides some new answers. For example, they write that the first farmers in Northern Europe learned the technique from migrating Southern Europeans.
Special investigation
DNA research has also been done before, but what makes this study special is that the researchers looked at a total of 249 million DNA base pairs of DNA from the nucleus. That is about two to five percent of the total genome of a human. The previous research looked at parts of mitochondrial DNA, which is only passed from mother to child, or at the Y chromosome, which only males have. The three hunter-gatherers from the grave on Gotland were found to be between 5300 and 4400 years old after C14 dating. The woman from the grave in Gökhem turned out to be 4900 years old. Earlier research had already shown that she was born 100 kilometers south of the tomb and that she was therefore part of a local population.
Analysis of the 249 million base pairs revealed that the three hunter-gatherers most closely resembled modern northern Europeans, especially Finns. The farmer's wife's genome most closely resembled that of modern southern Europeans from Greece and Cyprus. The researchers conclude from this that Scandinavians only became farmers after genetically different farmers from the South brought farming methods to the North. That the southern European farmers lived alongside the northern European hunter-gatherers for a long time before they finally started mixing with them, explains the genetic diversity among today's Europeans.
More about agriculture on Science24:
- The DNA Revolution
- Agriculture as a disastrous invention