In contrast to the research of Tyrrell and Lloyd-Jones, a recent genetic study has suggested that there may, after all, have been a substantial Anglo-Saxon contribution to the modern English gene pool - i.e. a large-scale population movement or immigration in the early Anglo-Saxon period.
3.8. Weale et al. tested alternative migratory models by collecting samples from living individuals in seven towns along an east-west transect of Central England and North Wales, in order to evaluate evidence of local genetic transitions, or male population migration (2002:1009). Data were compared with data from Friesland (thought to be one of the geographical sources for Anglo-Saxon invasion) and Norway (a source of Viking invaders) in order to look for evidence of continental immigration.
3.9. The results of analysis of genetic distance and population differentiation show that there were no significant within-England clinal patterns. In contrast, the two North Wales towns were found to differ significantly from each other as well as from the Central English towns. Even more importantly (from an Anglo-Saxon perspective), no significant differences were found between the Friesland and the Central England towns, whilst comparisons between Central England towns and Norway are (with just one exception, possibly explicable by small sample size) all significant. North Wales towns are statistically different from both the Friesland and Norway samples. As Weale et al. suggest, "[t]aken together, these results suggest considerable male-line commonality between Central England and Friesland." ( ibid. :1017) The lack of similarities between the Norway and Central England samples fail to provide any evidence of a substantial Norwegian Viking contribution to the Central English gene pool ( ibid .).
3.10. Weale et al. surmise that their results "indicate the presence of a strong genetic barrier between Central England and North Wales and the virtual absence of a barrier between Central England and Friesland." ( ibid. :1018) They conclude that the most likely explanation for this `barrier' is that "the Anglo-Saxon cultural transition in Central England coincided with a mass immigration event from the continent. Such an event would simultaneously explain both the high Central English-Frisian affinity and the low Central English-North Welsh affinity." ( ibid .) They note further that within the given parameters of the study, "an Anglo-Saxon immigration event affecting 50% - 100% of the Central English male gene pool is required [...however] 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 where indigenous males were reduced in number" ( ibid .).