Assessing the percentage of Viking paternal lineages in the UK and Ireland
We know little of the ethnic composition of Britain prior to the Roman and Anglo-Saxon invasions. The Ancient Britons were supposedly all Celts, belonging to haplogroup R1b. But there might have been earlier Germanic migrations. Nobody is sure of the actual impact of the Angles, Jutes and Saxon on the present population of Britain. However, it is possible to estimate the share of the later Scandinavian settlers.
Based on the assumption that haplogroup R1a was brought to the UK "almost exclusively" by the Vikings, we could calculate the percentage of paternal "Viking blood" in the British Isles by multiplying the percentage of R1a relative to its proportion in the source population. Vikings raiding Britain and Ireland came either from Denmark (in Eastern England) or Norway (Scotland, North-Western England, Wales, Ireland).
At present the proportion of R1a in Denmark is about 12 to 15%, against 27 to 30% in Norway.
To simplify things, let's say that England was exclusively Danish. There are 4.5% of R1a in England, 3x less than in Denmark. It would mean that 1/3 of the English have Danish Y-DNA. As Denmark has 45% of R1b, 30% of I1 and 5% of I2b1, it should be expected that about 15% of R1b, 10% of I1 and 1.5% of I2b1 in England are also of Danish origins.
This would leave about 52% of R1b, 4% of I1 and 3% of I2b1 of Anglo-Saxon or Celtic origins. Considering that the Celts were almost exclusively R1b and that the Anglo-Saxons came from Frisia, where R1b-S21+ is dominant, it makes sense to find such low percentage of I1 and I2b1.
In fact, the Netherlands and North Germany have a similar ration of I1 to I2b1 of 4 to 3 or 3 to 2, while in Norway the ration is about 35 to 1 and in Denmark 6 to 1.
Still in the Netherlands, compared to R1b the proportion of I1 is about 4.5 to 1, while it is 7 to 1 for I2b1.
If the above estimations are right, there should be 4.5x more Frisian R1b than I1 and 7x more than I2b1. So between 18% and 21% of the English males could be R1b of Anglo-Saxon/Frisian origins. This would leave about 32% of the population being R1b of Ancient Briton origin.
The rest of the population is made of Near-Eastern (E3b, J, G, K) and Balkanic (E3b, I2) lineages that came with the Neolithic farmers or during the Roman occupation.
In summary, the population of England could be composed of :
- 31.5% of Ancient Briton paternal lineages
- 11% of Near-Eastern paternal lineages
- 26.5% of Anglo-Saxon/Frisian paternal lineages (19.5% R1b + 4% I1 + 3% I2b1)
- 31% of Danish Viking paternal lineages (15% R1b + 4.5% of R1a + 10% I1 + 1.5% I2b1)
Because a low percentage of R1a in fact probably came with the Anglo-Saxons, it is likely that the above calculations overestimated the proportion of Vikings and underestimated that of the Anglo-Saxons.
One way of confirming the overall proportion would be to know the percentage of R1b subclades. S116- would be either Frisian or Danish, and should make about 55% of all R1b (i.e. 35% of the population). It will be very difficult to distinguish between Frisian and Danish R1b, as they are basically the same. But it does not matter so much as they are basically the same people.
R1b-S28+ is found at a higher percentage in Denmark than the Netherlands. However it is most common in Jutland, which was a source for both the Anglo-Saxon and Viking migrants. What is more, some S28+ might have come much earlier (1st or 2nd century BCE) with Belgic tribes from northern Gaul.
The real native Briton subclades like M222, M167 or M37, or just R1b-S116+* should reach about 30% in England, with the highest concentration in the South and West.
The case of Scotland should be easier than England. The proportion of R1a and I1 are almost equal, which would mean that almost all the Germanic blood there came from Norway, accounting for about 28% of the Scottish male lineages. There are under 6% of Near-Eastern lineages, and about 66% of Celtic lineages, with a high proportion of R1b-M222+.
Ireland is more complicated because the actual number of Viking settlers was probably quite limited, but Germanic haplogroups account for about 25% of the male lineages. The reason is that many English people settled in Ireland, bringing with them I1, R1a and R1b-S21 haplogroups. To make things even more complex, Northern Ireland has a lot of fairly recent Scottish lineages, who also brought Norwegian R1a and I1a with them.
R1a makes up some 3% of the Irish population. With the same reasoning as for England above, Norwegian Vikings lineages should account for about 9% (with 3% of R1b and 3% of I1).
This is unlikely, because of the higher proportion of R1b-S21 (11%), I1 (7%), I2b1 (4%), but also R1b-S28 (6.5%), which could also be Dutch, Danish or Norwegian, or maybe also from an earlier Belgic migration (which is documented). Let's say that 3.5% of R1b-S28 is Belgic, and 3% came later.
This way we have 14% of R1b, 7% of I1, 4% of I2b1 and 3% of R1a. This pattern doesn't match at all the Norwegian population, but fits right in between the Dutch and Danish one, pointing at an admixture, like the one found among the English.
Many surnames in Ireland are also English, further confirming that a big part of the Irish population (about one fourth) is of English descent on their paternal side.