There is an evidence discrepancy between:
1) The linguists who say that the widespread loss of the Celtic languages
and very few loan words into English can only be examined by mass
extermination of the local population by a mass immigration
2) Just about every other bit evidence which suggests that the number of
immigrants were relatively small
So we cannot just ignore the linguists evidence just because it does not
suit our plan and vice-versa.
However, the biological model of immigration can hypothesise that a more
successful elite would enjoy more breeding success and could explain
mathematically why a few Germans could turn into lots of them over 2 or 3
centuries and explain why we speak English.
There are a few problems that were not addressed and even the paper does not
I came to the same conclusion independently by examining different evidence.
The DNA does not prove that much yet. Germans may have been immigrants at a
much earlier date for a start. However, it does side with linguists which
propose large numbers of immigrants and displacement of the natives.
The new theory provides an adequate explanation of how relatively few tribes
of immigrants can become dominant. The model really needs to be much more
sophisticated before going into print.
Which fits you view best?
1) large number of Saxon (collective name for various tribes) immigrants
displacing and killing the natives to fit the linguists and DNA view
2) small number of immigrants and the linguistic and DNA evidence is
3) new "biological evolutionary" theory that the Saxons enjoyed a
competitive advantage as the Master Race (= political control of the best
resources), with a small group of immigrants (in a disparant collection of
tribes in southern and eastern Britain and the midlands) versus the natives
Brits and Welsh already subjugated by the Romans before them
4) a Comet landed on the Britons and wiped out lots of them
5) earlier immigrantion of German DNA types, but this does not fit the
linguists very well
It is probably a mixture of all this events, so it is not accepting one
hypothesis as pure and proven, but your own view as a tendency of what