Unfortunately, our speaker was unable to come to the Archaeology Group’s February meeting, so the scheduled talk (Schooners: design and people in 18th Century) was replaced by a summary of the secretary’s own research into The Neolithic – Early bronze Age transition in Britain.
Around 2400 BCE, there was a social change in Britain as metal was introduced and the Bronze Age began. Recent work on ancient DNA has identified a major genetic change at this time and 90% of the Neolithic genome was replaced by that of incoming Beaker people who carried Steppe ancestry. They brought new material culture with them in the form of Beaker pottery, metal tools and barbed and tanged arrowheads. They also had different burial practices and probably different beliefs and values from the later Neolithic peoples of Britain.
The research is looking at how this transition occurred. Was it achieved in a short time by a large number Beaker people arriving and colonising the country at the expense of the Neolithic population? Or was it achieved over a longer period of time with small numbers of migrants arriving regularly, mixing with the Neolithic population resulting in a gradual change in society?
The answer to these question might be revealed through an in depth study of Late Neolithic and Beaker activity in the landscape. Through the mapping of occupation sites, monuments and burials the degree of geographical separation between the local population and the incoming people could be revealed. If Beaker and Later Neolithic activity are distinct it might suggest that Beaker migrants kept themselves separate from the local population in order to maintain their identity. Alternatively, the occupation sites might over;ap suggesting integration of the two peoples. Whatever form the social transition took, the Beaker way of life became dominant and over a period of several hundred years the genetic makers of Steppe ancestry also came to predominate. The pervasiveness of the Seppe ancestry may be because it gave a survival advantage to those with those particular genes and they were therefore more likely to survive to adulthood and reproduce, passing their genes on to their children. Over 8 to 12 generations these genes would have increased in frequency in the population and the Neolithic alternatives would have decreased.
Although it is not yet known what all these genes control, several genes have been identified as being associated with decreasing skin pigmentation. Neolithic people originated from the middle east and carried genes for slightly more pigmented skin which would have given benefits in a Mediterranean environment with higher levels of ultraviolet light but at higher latitudes in Britain this pigmentation limits the production of vitamin D in the skin throughout the year. In order to maintain vitamin D levels Neolithic peoples would have become reliant on their diet to prevent vitamin D deficiency. Pork and beef offal and meat and dairy produce would have provided sufficient levels of Vitamin D. However this would impose a pastoral way of life on the people and maintaining their livestock would have been a higher priority than farming cereals and the archaeological record indicates that there is little evidence for cereal production at this time. Their diet would have been high in protein but low carbohydrate. A pastoral way of life is very mobile and this, combined with a lower carbohydrate intake and a lower energy intake, could have limited the birth interval for women; most pastoralist societies today have between 3-3.5 years between children compared with agricultural societies with around a 2 year interval.
There is much more evidence for cereal farming with Beaker sites, ard marks in the ground suggesting cultivation and cereal grains found at many occupation sites. With a less pigmented skin they would have been able to produce more vitamin D for more months of the year and therefore less reliant on diet for vitamin D. The archaeological record shows that sheep became more important and pigs much less so, although cattle still held a prominent place in their lives. With more carbohydrate in the diet and possibly less mobility, they would have been able to have children more often. In this way over 12 generations the Beaker genes may have become more frequent and explain the 90% replacement seen in the ancient DNA.
The research will help to explain why the arrival of the Beaker people changed the genetic and social structure in Britain between 2400-1600BCE.
Edrys Lupprian, March 2022