At https://anthropology.net/2020/05/30/ancient-dna-from-france-outline-comp… … the early farmers that moved through the Balkans into eastern and central Europe did not mix with the local hunter gatherers it is thought. This could be as a result of rapid migration over long distances, moving through the Danube valley into the northern European plain, However, in western Europe, when they came up against a big obstacle, the sea, things seem to have changed. This is an interesting study as in France the hunter gatherers were faced by a two pronged assault by farmers. One that arrived from the east and another that was expanding along the coastline – particularly in southern France, and via Spain to as far north as Brittany. Here they have found considerable admixture with hunter gatherers. In southern France, as much as 30% of hunter gatherer genes were preserved. Admixture was also high in Spain, Britain and Ireland. See https://doi.org.advances.sciencemag.org/content/6/22/eaaz5344