How the Anglo-Saxons outbred the British

From an IOL story:

Britain - The Anglo-Saxons who conquered England in the fifth century set up a system of apartheid that enabled them to master and outbreed the native British majority, according to gene research published on Wednesday.

In less than 15 generations, more than half of the population in England had the genes of the invaders, investigators say.

"The native Britons were genetically and culturally absorbed by the Anglo-Saxons over a period of as little as a few hundred years," said Mark Thomas, a University College London biologist.

"An initially small invading Anglo-Saxon elite could have quickly established themselves by having more children who survived to adulthood, thanks to their military power and economic advantage.

"We believe that they also prevented the native British genes getting into the Anglo-Saxon population by restricting intermarriage in a system of apartheid that left the country culturally and genetically Germanised," he said.

"This is what we see today - a population of largely Germanic genetic origin, speaking a principally German language."

UPDATE: Here is an audiovisual presentation based on a previous paper about Anglo-Saxon mass migration from the same team.

Proc. R. Soc. B doi:10.1098/rspb.2006.3627

Evidence for an apartheid-like social structure in early Anglo-Saxon England

Mark G. Thomas et al.

The role of migration in the Anglo-Saxon transition in England remains controversial. Archaeological and historical evidence is inconclusive, but current estimates of the contribution of migrants to the English population range from less than 10 000 to as many as 200 000. In contrast, recent studies based on Y-chromosome variation posit a considerably higher contribution to the modern English gene pool (50–100%). 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. It is likely that such a disadvantage would lead to differential reproductive success. We examine the effect of differential reproductive success, coupled with limited intermarriage between distinct ethnic groups, on the spread of genetic variants. Computer simulations indicate that a social structure limiting intermarriage between indigenous Britons and an initially small Anglo-Saxon immigrant population provide a plausible explanation of the high degree of Continental male-line ancestry in England.

Link (pdf)