Haplogroup I1 (Y-DNA) - Britain

Britain

See also: Prehistoric settlement of the British Isles

In 2002 a paper was published by Michael E. Weale and colleagues showing genetic evidence for population differences between the English and Welsh populations, including a markedly higher level of Y-DNA haplogroup I in England than in Wales. They saw this as convincing evidence of Anglo-Saxon mass invasion of eastern Great Britain from northern Germany and Denmark during the Migration Period. The authors assumed that populations with large proportions of haplogroup I originated from northern Germany or southern Scandinavia, particularly Denmark, and that their ancestors had migrated across the North Sea with Anglo-Saxon migrations and Danish Vikings. The main claim by the researchers was

that an Anglo-Saxon immigration event affecting 50–100% of the Central English male gene pool at that time is required. We note, however, that our data do not allow us to distinguish an event that simply added to the indigenous Central English male gene pool from one where indigenous males were displaced elsewhere or one where indigenous males were reduced in number … This study shows that the Welsh border was more of a genetic barrier to Anglo-Saxon Y chromosome gene flow than the North Sea … These results indicate that a political boundary can be more important than a geophysical one in population genetic structuring.

In 2003 a paper was published by Christian Capelli and colleagues which supported, but modified, the conclusions of Weale and colleagues. This paper, which sampled Great Britain and Ireland on a grid, found a smaller difference between Welsh and English samples, with a gradual decrease in Haplogroup I frequency moving westwards in southern Great Britain. The results suggested to the authors that Norwegian Vikings invaders had heavily influenced the northern area of the British Isles, but that both English and mainland Scottish samples all have German/Danish influence.