To a point, but that wouldn't be useful in this sort of case. We're talking about people who lived 80 generations ago, many of them before the Saxon and Norman invasions that both flooded the English gene pool. I'm English with no 'known' African ancestry. But it's quite possible I have some African ancestry from 1800 years ago, but I might also have African ancestry from one ancestor in medival times, and perhapse an ancestor from the West Indies sugar plantation days. How would you ever tease that out? It would only add up to a few percent of DNA but would be all over the map. Many brits probably have ancestries all over the place like this. What about ancestors who were Berbers? They have largely Visigoth ancestry, but are from North Africa.
In any case, the idea that this specific evidence isn't of value 'because DNA' is just daft.
> They have largely Visigoth ancestry, but are from North Africa.
The berbers do not have "largely visigoth" ancestry. The berbers are descendents of Numidians and Mauri, and they have a north african origin and the majority of north africans (algeria, morocco, tunisia) regardless of language (arabic or berber) can be identified genetically by the "berber marker." Recent population studies prove the despite numerous military conquests of north west africa there was not a population replacement.
We inherit the genes of our parents not completely mixed but in large chunks. So someone who is first generation mixed race while have large continuous regions of their genome from one race or the other. If two such people have children they will have the same amount of genes from each race as their parents[1] but the continuous regions will be smaller. So from the average length of regions which we can attribute to different founder populations we can estimate how long ago the admixture happened.
[1] This is not completely true as we seldom inherit exactly 25% of our genome from any grandparent, but it is usually pretty close.
To a point, but that wouldn't be useful in this sort of case. We're talking about people who lived 80 generations ago, many of them before the Saxon and Norman invasions that both flooded the English gene pool. I'm English with no 'known' African ancestry. But it's quite possible I have some African ancestry from 1800 years ago, but I might also have African ancestry from one ancestor in medival times, and perhapse an ancestor from the West Indies sugar plantation days. How would you ever tease that out? It would only add up to a few percent of DNA but would be all over the map. Many brits probably have ancestries all over the place like this. What about ancestors who were Berbers? They have largely Visigoth ancestry, but are from North Africa.
In any case, the idea that this specific evidence isn't of value 'because DNA' is just daft.