The Anglo-Saxon migration and the formation of the early English gene pool

Abstract

The history of the British Isles and Ireland is characterized by multiple periods of major cultural change, including the influential transformation after the end of Roman rule, which precipitated shifts in language, settlement patterns and material culture1. The extent to which migration from continental Europe mediated these transitions is a matter of long-standing debate2–4. Here we study genome-wide ancient DNA from 460 medieval northwestern Europeans—including 278 individuals from England—alongside archaeological data, to infer contemporary population dynamics. We identify a substantial increase of continental northern European ancestry in early medieval England, which is closely related to the early medieval and present-day inhabitants of Germany and Denmark, implying large-scale substantial migration across the North Sea into Britain during the Early Middle Ages. As a result, the individuals who we analysed from eastern England derived up to 76% of their ancestry from the continental North Sea zone, albeit with substantial regional variation and heterogeneity within sites. We show that women with immigrant ancestry were more often furnished with grave goods than women with local ancestry, whereas men with weapons were as likely not to be of immigrant ancestry. A comparison with present-day Britain indicates that subsequent demographic events reduced the fraction of continental northern European ancestry while introducing further ancestry components into the English gene pool, including substantial southwestern European ancestry most closely related to that seen in Iron Age France5,6.

Unappreciated Subcontinental Admixture in Europeans and European Americans: Implications for Genetic Epidemiology Studies

“…The demonstration that European Americans are ancestrally heterogeneous has implications for calibrating locus-specific ancestry analysis 19 with respect to the number of generations since admixture began. Admixture dates estimated for European Americans corresponded to the large-scale Migration Period in Europe (300-800 AD) 45 , and were consistent with gene flow after the end of Roman Empire described in ancient DNA studies of the Viking Age 11 and Anglo-Saxon migrations 12 . Moreover, our results support the occurrence of subcontinental ancestry-related assortative mating as a social factor that shaped the genetic structure of European Americans in the US 46 .…”

“…Despite genetic studies highlighting a clear pattern of North-to-South genetic variation in Europe [8][9][10] and strong evidence of admixture within Europe by ancient DNA analysis 11,12 , European-ancestry populations are generally treated in association models as stratified but not as admixed at the subcontinental level.…”

“…Despite genetic studies highlighting a clear pattern of North-to-South genetic variation in Europe 8–10 and strong evidence of admixture within Europe by ancient DNA analysis 11,12 , European-ancestry populations are generally treated in association models as stratified but not as admixed at the subcontinental level. As a result, genetic epidemiology studies of Europeans or European Americans usually control for potential confounding effects of population stratification using genome-wide ancestry estimated by principal components analysis 13 , but do not control for locus-specific ancestry, which is inherent to admixed populations 14 .…”

Imputed genomes and haplotype-based analyses of the Picts of early medieval Scotland reveal fine-scale relatedness between Iron Age, early medieval and the modern people of the UK

“…However, two Viking Age Orcadians (VK204 and VK205) are intermediates between the British and Scandinavian clusters, consistent with previous results finding evidence of admixture in these individuals between British-like and Scandinavian-like ancestries [ 9 ]. The early medieval individuals from England are intermediate between modern English people and Scandinavians, which is consistent with various degrees of admixture between Iron Age groups from England and immigrants from northern/central Europe [ 14 , 17 , 18 ]. These results agree with the pseudo-haploid-based analyses of the BAL003 and LUN004 genomes, showing a broad affinity to modern western Europeans (section S1.3 in S1 Text and S10 , S12 – S15 and S18 Figs), but with a much-improved resolution.…”

“…300–800 CE), before and following the collapse of the Western Roman Empire. In Britain, Angles, Saxons and other Germanic-speaking peoples, likely originating in Scandinavia, the Low Countries and parts of Germany, settled predominantly in south-eastern and central Britain with genetic evidence of extensive admixture with local populations carrying genetic ancestry from the Iron Age [ 14 , 17 , 18 ]. During the so-called ‘Viking Age’ (starting about 800 CE), Scandinavians settled in the ‘Danelaw’ in northern and eastern England, as well as in the coastal areas of Ireland and northern and western Britain [ 19 ], which led to admixture with the inhabitants of Ireland and western and northern Britain over nearly four centuries [ 9 ].…”