Ancient burials near Stonehenge reveal how cultures merged in the Bronze Age

The Early Bronze Age in Britain was a time of great change. Not only did this period see a shift in the dominant culture of the island, but studies have found that there was a huge change in the genetics of the people living there too.

Recent narratives have framed this in terms of waves of invaders sweeping across the channel and displacing the people who were already living in Britain.

But a new study looking at both the genetics and culture of Britain between 4,500 and 4,000 years ago is showing that the picture is far more complex. Rather than this shift representing a sudden, violent turnover of populations, it was instead a gradual integration and merging of communities.

Dr Tom Booth, a former postdoctoral researcher at the Museum now based at The Francis Crick Institute, has been delving deeper into the genetics of these ancient people.

'When you look at this change more carefully, it is a much more gradual process, probably taking the best part of 500 years' explains Tom. 'It looks like this new population came over from the continent and settled areas of the landscape where the local Neolithic population weren't living.

'Two groups that were genetically quite different from one another lived largely in parallel, having children with each other only occasionally.'

This situation persisted for at least three hundred years, until sometime around 4,000 years ago when the two groups started mixing more liberally.

It is at this point that we can see the older population who inhabited Britain during the Neolithic had only a small overall genetic legacy.

Yet while these different groups of people may not have initially been frequently having children together, they were extensively interacting in other ways, sharing and adopting aspects of each other's cultures.

In 2018, Museum scientists were part of the largest study ever conducted using DNA from archaeological human remains from Britain, and found that the migration of these 'Beaker people', so-called because of their distinctive pottery style, led to a near complete switch in the genomes of the British population at this time.

A cultural interchange

Around 4,500 years ago Britain was inhabited by groups of people who lived in small, semi-nomadic communities spread across the landscape.

While these people did not typically form large population centres, they did come together to build massive structures, the most famous of which is Stonehenge. These monuments were presumably central to their belief system.

Around this time, a new population of people arrived from the continent. They brought with them what is known as Bell Beaker cultures. Bell Beaker groups can be tracked through their use of distinctive Beaker pottery, but this pottery was also often accompanied by new funerary practices and skills such as metalworking, suggesting Beakers reflected a larger overall change in culture, technology, ideology, ritual and belief. There is evidence the local population of Britain rapidly adopted this type of pottery and other associated traits from the newcomers.

But equally, the team have been showing that there was an exchange going in the opposite direction.

By looking at the genetics of people buried in the landscapes around Stonehenge during the Bronze Age, they have been able to build up something of a family tree. No-one in this set of relatives from the Stonehenge landscape had any ancestry from the groups that actually built Stonehenge.

Prof Ian Barnes, a research leader on ancient DNA at the Museum, says, 'There are loads of Neolithic structures around Stonehenge and it's this landscape, that the Beaker people use as a prestigious place to bury their dead.

'What is interesting is that even though it wasn't these people's biological ancestors who built Stonehenge, they referenced and incorporated these monuments into their belief systems very quickly and they were adapting parts of the local culture.'

This parallel situation in which both peoples were living and interacting, but not mixing much biologically, lasted for perhaps up to 500 years.     

Then, there was a tipping point when the populations started having children together more extensively. What is interesting here is the genetics of the local Neolithic population were almost completely gone: there was a 90% replacement of the ancestry of these people.

What caused this tipping point is hard to discern. 

Dr Selina Brace, a researcher in ancient DNA at the Museum, explains, 'Just before the point where we can infer interbreeding, there was a hybrid culture between what came before and what came after.

'It is almost like it takes them a few hundred years to iron it out, but then they find an accord and develop this set of ideas that incorporates both cultures into something that they can all subscribe to.' 

A small legacy

The picture of Britain during this time is hugely complex.

In part it is muddied due to the wide range of burial practices during the Bronze Age. Previous work by Tom and his colleagues has shown how Bronze Age inhabitants of Britain were doing everything from leaving bodies out on the ground to simply decompose, to keeping body parts of their ancestors in their houses. 

Just before the new groups arrive around 2500 BC, the Neolithic inhabitants of Britain were cremating their dead or treating them in ways which left no archaeological record, so no remains are left for researchers to study. It makes it hard to know exactly who was living where, and when. The incoming groups more often buried their dead, meaning they are much more visible archaeologically.

If local populations continued cremating, it would explain why the change in ancestry previously appeared so sudden. We can only see that the local population are still there in the genetic evidence when they have children with the new groups who were burying their dead.

Why the Neolithic groups have such a small genetic legacy in later populations remains unanswered. This new study does show that the population turnover was unlikely due to a violent invasion, as there are seemingly fewer markers of violence on human skeletons dating to this time than those from the previous Neolithic period. There is also little evidence of extensive burning or destruction of existing structures.  

One plausible explanation is that large parts of Britain were less populous at the time when new Beaker populations began to arrive.