<P> An examination of Y - chromosome variation, sampled in an east--west transect across England and Wales, was compared with similar samples taken in Friesland and Norway . Friesland was selected for the study due to it being regarded as a source location for Anglo - Saxon migrants, and because of the similarities between Old English and Frisian . Samples from Norway were also compared, as this is a source of the later Viking migrations . It found that in England 50% to 100% of paternal genetic inheritance was derived from incomers originating in the Germanic coastlands of the North Sea . </P> <P> Research published in 2003 on Y - chromosome marker variation, taken from a larger sample population and from more sites throughout Britain, came to a different conclusion . This study suggested that in most of England, continental (North German and Danish) paternal genetic input varied between 20% and 40%, with York forming an outlier at about 60% . Southern England, including Kent, had markedly lower frequencies of non-indigenous Y - chromosome markers than eastern England, where Danish Viking settlement is attested . However, the study could not distinguish between North German and Danish populations, thus the relative proportions of genetic input derived from the Anglo - Saxon settlements and later Danish Viking colonisation could not be ascertained . </P> <P> Historical evidence suggests that following the Anglo - Saxon transition, people of indigenous ethnicity were at an economic and legal disadvantage compared to those having Anglo - Saxon ethnicity . This has led to the development of the "apartheid - like social structure" theory to explain this high contribution to the modern gene pool, where the proportion of settlers would be smaller . </P> <P> This view has been challenged by JE Pattison, who suggested that the Y - chromosome evidence could still support the idea of a small settlement of people without the apartheid - like structures . In addition, there is no reliable method for dating the influx of genetic material into Britain from the Continent; and the genetic similarities between people on either side of the North Sea may reflect a cumulative process of population movement, possibly beginning well before the historically attested formation of the Anglo - Saxons or the invasions of the Vikings . The' apartheid theory' has received a considerable body of critical comment, especially the genetic studies from which it derives its rationale . Problems with the design of Weale's study and the level of historical naivete evidenced by some population genetics studies have been particularly highlighted . </P>

The invasion of the anglo saxons in england