New research shows climate was the key factor impacting the movement of Europe’s first farmers

The research, a collaboration between the University of Roehampton, the University of Cambridge and several other institutions, combined archaeological data with paleoclimatic reconstructions to show for the first time that the climate dramatically impacted the migration of people across Europe, causing a dramatic slowdown among 6,100 BC and 4,500 BC. C.

The research team, including Dr. Lia Betti, Senior Lecturer at the University of Roehampton, assembled a large database of the early arrival dates of Neolithic farmers across the continent and studied the speed of their migration in relation to the climatic reconstructions of the time. They also re-analyzed ancient DNA data to understand the interaction between early farmers and local hunter-gatherers.

They discovered that migration started quickly from Southeast Europe, with Neolithic farmers expelling the existing hunter-gatherer population. This was demonstrated by how little DNA was mixed between the two groups. As they moved north, the weather became less suitable for the crops they had purchased with them. Their rate of movement decreased, changing the way they interacted with local hunter-gatherers, which can be seen through a greater genetic mix of the two groups.

To prove that weather was the key factor causing the migration slowdown, the team used paleoclimatic reconstruction to calculate the number of Degree Growth Days (DAG) for the areas that farmers encountered during their expansion. GDDs are commonly used in agriculture as a measure of the heat available in a year for crops to grow. Expansion slowed along different migration routes each time the first farmers arrived in regions where the amount of GDD was less than that required to support the original cultivation package. This conclusion was supported by the fact that the only route that had not slowed down in expansion was along the Mediterranean, suggesting that those who moved along that path could continue to expand rapidly in favorable warm weather .

By comparing ancient DNA data from local hunter-gatherers and early farmers, the authors also demonstrated that challenging climatic conditions for agriculture in northern Europe led to closer relationships between the two groups and increased mixing. Exchanges of goods and knowledge of local hunting may have allowed early farmers to persist in these regions despite low crop yields.

This research shows how the climate has significantly impacted the migration of people since the beginning of our history. The climatic suitability of places to live and settle played a key role in determining where different human groups could thrive, which in turn changed the genetics of entire continents.

Dr. Lia Betti of the University of Roehampton said: “This study required a great deal of work to examine hundreds of archaeological articles, books and reports in different languages ​​to build a detailed model of the expansion of agriculture in Europe. We are very proud that our database will now be available to the scientific community and the public, to facilitate future research. We have also created new methods to identify the main routes of past human migrations and determine if the climate had a significant impact, which hope will allow us to investigate the reasons behind the prehistoric waves of migration in other areas of the world. ”