Deciphering the DNA of the Bell Beaker Complex

PART.2

BEAKER BRITAIN

Due to the amazing preservation of aDNA from ancient British individuals, the team was able to examine the region in minute detail. Rather than maintaining the genetic profile of their Neolithic predecessors (who were closely related to Iberian early Neolithic farmers), the results showed that British Bell Beaker populations were in fact more closely related to those from central Europe. This suggests that, although the Beaker Complex spread between Iberia and central Europe through the movement of ideas, in Britain its expansion occurred through the movement of people, and in some numbers.

This figure from the Nature paper that recently published the results of this project starkly illustrates the rapid integration of Continental Beaker Complex-associated groups into the British population. Each bar represents the entire genome of one sampled individual from Britain: blue indicates the proportion of Neolithic ancestry, and red the proportion of central European-associated lineages. (Image: Nature and I Olade et al.)

As mentioned before, both the ‘All-Over-Cord’ and ‘Maritime’ Beaker designs are known in Britain, suggesting cultural influences from both central Europe and Iberia. It would seem logical that these two separate, although linked, styles would have been introduced to the region by different groups – but the new genetic results seem to indicate that this was not the case. Rather, regardless of pottery style, all the sites studied suggest a shared origin with central European Beaker populations, with no evidence for the migration of Iberian Beaker people into Britain at all.

This central European population movement into Britain was swift and hugely successful, DNA analysis suggests. After 2450 BC, when the Beaker Complex first arrived in the region, all sampled individuals from Britain show an abrupt change in their genome, with central European Bell Beaker-associated lineages suddenly accounting for the vast proportion of their overall ancestry. Over the next few hundred years, the proportion of this migrant DNA continued to vary slightly, indicating that some mixture with local Britons was ongoing – although it still accounted, on average, for at least 90% of ancestry. But by the end of the Beaker period the population had completely homogenised, and it seems that the Neolithic peoples of Britain – the ones who built Stonehenge, traversed the Sweet Track, and settled Skara Brae – had all but disappeared.

What could have caused such a rapid disappearance of Neolithic Britons? For now, the answer remains unknown, and opens up a lot of new questions. How did a seemingly thriving population evaporate from the gene pool? There is no evidence to suggest a hostile invasion, although it does, of course, remain a possibility. Other scenarios include an environmental change or catastrophe that the indigenous population could not adapt to, or new diseases that the Beaker migrants may have brought with them against which the local people had no natural resistance. Additionally, the Neolithic British population might have declined when they were forced to shift to a more pastoralist lifestyle after a period of unsuccessful crop farming.

The Amesbury Archer, at Boscombe Down, Wiltshire, was discovered with a plethora of Bell Beaker-associated grave goods. (Image: Wessex Archaeology)

We must also ask, where did these newcomers migrate from? The aDNA project found that the British Bell Beaker groups, particularly those in the south, were most closely related to individuals whose remains were recovered from the Oostwoud- Tuithoorn site in the West Frisia region of the Netherlands. The parallels were striking: both groups presented with an almost identical percentage of steppe-related ancestry. This does not necessarily mean that people from Oostwoud were the ones migrating into Britain, but it does suggest that they had a shared common ancestor. Whoever settled Oostwoud, most likely moved on to settle in Great Britain too.

Widening this picture, as the team also analysed the genetic profiles of Neolithic and later Bronze Age populations, they were able to draw a timeline of different genetic traits and their entry into Britain. Among these, the researchers noticed that between the Neolithic period and the start of the Beaker period the genes for lighter skin and eye pigmentation significantly increased in frequency – before this, Britain’s inhabitants seem to have had much darker skin and hair. (The Mesolithic population, exemplified by the individual known as Cheddar Man, was darker still – see CA 337.) The arrival of the Beaker Complex seems, therefore, not only to have completely altered the genetic makeup of the British peoples, but also transformed their physical appearance. One trait that the wave of incomers did not introduce to any great extent, however, was the ability to digest lactose. The gene was not found with any frequency for this period, meaning that dairy consumption would not have become widespread in Britain, or indeed Europe, until some time within the last 3,500 years (see CA 334).