The Return of the Beaker Folk? : Rethinking Migration and Population Change in British Prehistory
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This is a repository copy of The return of the Beaker Folk? : Rethinking migration and population change in British prehistory. White Rose Research Online URL for this paper: https://eprints.whiterose.ac.uk/169610/ Version: Accepted Version Article: Armit, Ian and Reich, David (Accepted: 2020) The return of the Beaker Folk? : Rethinking migration and population change in British prehistory. Antiquity. ISSN 0003-598X (In Press) Reuse This article is distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs (CC BY-NC-ND) licence. This licence only allows you to download this work and share it with others as long as you credit the authors, but you can’t change the article in any way or use it commercially. More information and the full terms of the licence here: https://creativecommons.org/licenses/ Takedown If you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing [email protected] including the URL of the record and the reason for the withdrawal request. [email protected] https://eprints.whiterose.ac.uk/ Antiquity For Peer Review The return of the Beaker Folk? Rethinking migration and population change in British prehistory Journal: Antiquity Manuscript ID AQY-RE-20-251.R1 Manuscript Type: Research Article Date Submitted by the 07-Dec-2020 Author: Complete List of Authors: Armit, Ian; University of York, Archaeology Reich, David; Harvard Medical School Keywords: Beaker, migration, Neolithic, Chalcolithic, aDNA Research Region: Britain & Ireland Recent aDNA analysis has demonstrated that the centuries surrounding the arrival of the Beaker Complex in Britain witnessed a massive turnover in the genetic make-up of the population. Here we consider the Abstract: archaeological implications of this finding, and propose two hypotheses - Beaker Colonisation and Steppe Drift - that might help us understand the underlying social processes, and propose directions for future research. Cambridge University Press Page 1 of 21 Antiquity 1 2 3 4 The return of the Beaker Folk? Rethinking migration and population 5 6 change in British prehistory 7 8 9 Ian Armit1 and David Reich2,3,4,5 10 11 12 1 13 Department of Archaeology, University of York, King’s Manor, Exhibition Square, York 14 YO1 7EP 15 16 2 Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA 17 3 18 Department of Human Evolutionary Biology, Harvard University, Cambridge, MA 02138, 19 USA 20 21 4 Broad Institute of HarvardFor and MIT, Peer Cambridge, Review MA, 02142, USA 22 23 5 Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA 24 25 26 27 28 Abstract 29 30 31 Recent aDNA analysis has demonstrated that the centuries surrounding the arrival of the 32 33 Beaker Complex in Britain witnessed a massive turnover in the genetic make-up of the 34 35 population. Here we consider the archaeological implications of this finding, and propose 36 37 two hypotheses - Beaker Colonisation and Steppe Drift - that might help us understand the 38 underlying social processes, and propose directions for future research. 39 40 41 42 Keywords: Beaker; migration; Neolithic; Bronze Age; Chalcolithic; aDNA 43 44 45 The Beaker Complex in Britain and Europe 46 47 48 49 One of the major marker points in British prehistory is the appearance of Beaker pottery in 50 the mid-third millennium BC (FIG 1), occurring as part of a ‘cultural package’ characterised 51 52 by single inhumation burials, Continental-style archery equipment and objects of gold and 53 54 copper. Based on the available radiocarbon dates, the ‘Beaker Complex’ is often viewed as 55 56 having originated in Iberia around 2750 BC (Cardoso 2014), from where it spread rapidly 57 across much of Europe and north-west Africa (FIG 2), arriving in Britain from around 2450 58 59 BC (Jay et al. 2019: 75). 60 1 Cambridge University Press Antiquity Page 2 of 21 1 2 3 4 5 For most of the twentieth century, the spread of the Beaker Complex was interpreted as the 6 7 product of migration. Although founded principally on the marked changes evident in 8 material culture and burial practices (not least the form and decoration of Beaker vessels 9 10 themselves), this hypothesis was strengthened in Britain by the observation of a shift in the 11 12 average cranial shape in burial populations: from the relatively more dolichocephalic (long- 13 14 headed) shape of Neolithic populations, to the relatively more brachycephalic (round-headed) 15 individuals associated with Beakers (FIG 3). 16 17 18 19 During the 1960s scepticism began to grow about the primacy of migration as a vector of 20 21 social change in prehistory.For Nonetheless, Peer even Review in Grahame Clark’s classic statement on the 22 inadequacy of models founded on putative invasions, the intrusive nature of the Beaker 23 24 Complex remained essentially unquestioned (Clark 1966: 160). It was only in the mid-1970s, 25 26 with the consolidation of processual approaches, that alternative explanations began to gain 27 traction. Foremost among these was the suggestion that the Beaker Complex related to the 28 29 spread of a prestige set of objects, practices and beliefs among the upper echelons of society 30 31 at the start of the European Bronze Age (e.g. Burgess and Shennan 1976). The uptake of this 32 33 new elite cultural package was suggested to have been promoted by its association with the 34 prestigious new metal, and/or with the spread of religious behaviours involving the 35 36 consumption of alcohol (e.g. Sherratt 1987). Even the change in skull shape associated with 37 38 the appearance of Beaker pottery in Britain could potentially be accounted for as the result of 39 40 deliberate or accidental cranial shaping (Parker Pearson et al. 2016: 625). Nonetheless, the 41 most detailed and authoritative studies on the Beaker Complex in Britain have held out the 42 43 possibility of some level of migration from the Continent, even if restricted to relatively small 44 45 numbers (e.g. Needham 2005). 46 47 48 The recent emergence of genome-wide analysis of ancient DNA provides, for the first time, a 49 50 means to investigate the question of migration directly, at the population scale, through the 51 52 genetic signatures of the individuals buried with Beaker Complex artefacts. Unlike 53 osteological or isotopic analysis, these genetic data provide information not only on the 54 55 individuals themselves, but on the ancestral populations from which they derive. 56 57 58 59 The new genetic data 60 2 Cambridge University Press Page 3 of 21 Antiquity 1 2 3 A recent study involving the present authors presented genome-wide data from 400 4 5 individuals spanning the Neolithic to the Middle Bronze Age, including 226 associated with 6 7 distinctive artefacts belonging to the Beaker Complex (Olalde et al. 2018). This work 8 produced two central conclusions relevant to the mechanisms by which the Beaker Complex 9 10 spread. 11 12 13 14 Firstly, the study demonstrated that while Beaker Complex individuals in Iberia derived most 15 of their ancestry from local, Neolithic farming groups, those in Central Europe had a quite 16 17 different genetic profile. Earlier aDNA analysis had demonstrated that the centuries from 18 19 around 3000–2600 BC witnessed the spread into northern and Central Europe of populations 20 21 most of whose ancestry derivedFor ultimately Peer from Review Early Bronze Age pastoralists associated 22 with the Yamnaya cultures of the Eurasian steppe (e.g. Haak et al. 2015; Allentoft et al. 23 24 2015). By the end of the Neolithic, all sampled populations in these areas (Corded Ware 25 26 Culture) had substantial proportions of steppe ancestry, although there was considerable local 27 variation in the precise amount. It was these communities who adopted the Beaker Complex 28 29 in Central Europe. This contrast between Iberian and Central European Beaker Complex 30 31 communities is exemplified by the Y-chromosome data: those in Iberia comprise Y- 32 33 chromosome lineages common since the start of the Neolithic in that region, while those in 34 Central Europe are dominated by a single lineage (RIb-M269) derived from the steppe 35 36 (Olalde et al. 2018). The cultural traits associated with the Beaker phenomenon in 37 38 Continental Europe did not, therefore, spread principally through migration, but must have 39 40 involved the movement of ideas between populations of distinct genetic heritage. 41 42 43 It is the study’s second main conclusion, however, that is most relevant here. Whereas 44 45 Neolithic individuals from Britain (n=51) lack any trace of Continental/steppe ancestry, all 46 those associated with Beaker Complex artefacts (n=37), and all those from the subsequent 47 48 Early and Middle Bronze Ages (n=67), display large amounts (FIG. 4). More than 90% of 49 50 these Beaker Complex and later male individuals, for example, belong to Y-chromosome 51 52 haplogroup RIb, previously absent in Neolithic Britain but a definitive indicator of steppe 53 ancestry common in Central Europe, demonstrating the arrival of substantial numbers of men 54 55 from the Continent. Mitochondrial haplogroups not previously present in Britain (e.g. I, R1a 56 57 and U4) show that women also moved in substantial numbers at this time. Thus, while 58 59 genetic data do not preclude some degree of male-bias in the westward spread of Steppe 60 ancestry (e.g. Kristiansen 2017), at least in Britain we can rule out scenarios of male-only 3 Cambridge University Press Antiquity Page 4 of 21 1 2 3 Steppe ancestry spread. The genetic evidence, assessed at the level of the whole genome, 4 5 shows a replacement of 93% of the gene pool in Britain, suggesting that the arrival of the 6 7 Beaker Complex correlates with a massive turnover of population during the last centuries of 8 the third millennium BC.