Aveline’s Hole, a cave in Somerset. Mesolithic humans remains found at this site were used in the study.

A recent ancient DNA study looking at the genetics of Neolithic Britons provides strong evidence to suggest that the shift to farming in Britain was due to migration from the Continent and not from local populations adopting agricultural methods – something that has been hotly debated for decades.

On the Continent, previous studies have shown that Neolithic farming populations most likely originated around the Aegean, spreading across Europe via two main paths: one along the Mediterranean (the ‘Mediterranean route’) and the other through central and northern Europe (the ‘Danubian route’). The level of admixture in their genomes indicates that these Neolithic farmers repeatedly mixed with the local Mesolithic hunter-gatherers over a number of generations.

In Britain, however, this recent study shows that the story is slightly different. A team from the Natural History Museum and University College London analysed the whole genomes of six individuals dating to the Mesolithic and 67 individuals dating to the Neolithic. The samples came from across Britain, from the south coast to Orkney.

This graph shows the proportion of Mesolithic DNA in relation to Neolithic DNA (in blue), within each sampled population. (IMAGE: Nature and Brace et al.)

The results showed that, while Mesolithic Britons were genetically similar to other western European hunter-gatherers, their Neolithic successors retained little of this DNA. Instead, most of their ancestry is probably attributed to the same Aegean Neolithic farmers who first migrated across Europe, spreading agriculture in their wake. In particular, it seems that the majority of Neolithic Britons most likely came to the region via the Mediterranean route of migration. The team suggests it is likely they originated in Iberia, spread up through France, either via the Atlantic seaboard or through southern France, and then crossed the Channel. A small portion of ancestry from populations who took the Danubian route through Europe was also found in the Neolithic Britons’ DNA but at a level that the team interprets as consistent with these Iberian populations mixing with central Europeans before entering Britain.

Once there, it does not appear that these Neolithic farmers mixed with the local hunter-gatherer populations very frequently, with only a low level of genetic admixture present. This is consistent with the levels already seen from earlier interactions on the Continent. In particular, populations from Wales and south-west and central England appear to have remained almost completely separate from the local population, although there was more admixture seen in south-east England, and especially in Scotland.

In addition to migration and integration, the team also assessed the genomic data for skin pigmentation. They found that while Mesolithic individuals were predominantly dark-skinned, by around 6000 BC variations in skin pigmentation began to take root in Europe.

This article appeared in CA 352.

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