British Neolithic populations share genetic similarities with Iberian Neolithic individuals and there was little interbreeding between these populations and local Mesolithic foragers, according to a paper published online this week in Nature Ecology & Evolution. The findings indicate that farming was introduced to Britain by continental Neolithic farmers following a route along the Mediterranean.

Farming in continental Europe arrived with Neolithic farmers of Aegean ancestry via two main routes: one along the Mediterranean, and the other through Central into Northern Europe. These expanding populations interbred with local Mesolithic foragers along the way. In Britain, Neolithic cultures appeared around 4000 BC, nearly a millennium after the transition to farming in adjacent regions of continental Europe. However, the origins of British Neolithic populations have remained unclear.

Mark G. Thomas, Ian Barnes and colleagues analysed genome-wide data from 6 Mesolithic and 67 Neolithic individuals found in Britain, dating from 8500-2500 BC. The authors found that Neolithic populations in Britain were primarily descended from Aegean Neolithic farmers and have similarities with Iberian Neolithic individuals. They also show that there is little evidence of substantial interbreeding between the Mesolithic and incoming Neolithic British individuals. The authors found that this shift in ancestry occurred with the transition to farming in Britain. Unlike other European regions, this transition was not influenced by detectable interbreeding with local foragers. The authors argue that the genetic similarities between British Neolithic and Iberian Neolithic individuals indicate that continental farmers colonized Britain mainly following a route along the Mediterranean.