Genetic differentiation between contemporary British and Irish populations

 

"This seems to me a thing to be noticed, that just as the men of this country are, during this mortal life, more prone to anger and revenge than any other race, so in eternal death the saints of this land, that have been elevated by their merits, are more vindictive than the saints of any other region." - Gerald of Wales, Topographia Hibernica 

"The Irish hate our order, our civilization, our enterprising industry, our pure religion. This wild, reckless, indolent, uncertain and superstitious race have no sympathy with the English character. Their ideal of human felicity is an alternation of clannish broils and coarse idolatry. Their history describes an unbroken circle of bigotry and blood." - Benjamin Disraeli

"Besides some small islands round about Britain, there is also a large island, Ierne, which stretches parallel to Britain on the north, its breadth being greater than its length. Concerning this island I have nothing certain to tell, except that its inhabitants are more savage than the Britons, since they are man-eaters as well as heavy eaters, and since, further, they count it an honourable thing, when their fathers die, to devour them, and openly to have intercourse, not only with the other women, but also with their mothers and sisters; but I am saying this only with the understanding that I have no trustworthy witnesses for it; and yet, as for the matter of man-eating, that is said to be a custom of the Scythians also, and, in cases of necessity forced by sieges, the Celti, the Iberians, and several other peoples are said to have practised it." - Strabo, Geographica

                                                                                

How different (or similar?) are the Irish and their beloved British neighbours? The answer will more than likely piss off both armchair republicans and loyalists alike. The latter claiming to be the true original inhabitants of the Cruithin only retaking what was always rightfully theirs whilst the former claim to be bastard descendants of Egpytian pharaohs and shipwrecked Basque pescaderos. The sad truth is that both factions are far more interrelated to one another than both would be comfortable admitting regardless of who was what or where going back to antiquity because the British and Irish relationship is far deeper than antiquity. As old to antiquity as antiquity is to us now in 2021. But in the case of the Irish there has been substantially less homogenisation since then. Almost going back as far to the late bronze age (but unfortunately no samples have yet been published from Ireland).

To illustrate this elevated single grave/rhineland bell beaker drift in Ireland (which I believe peaks in Connaught where y-haplogroup R1b reaches its highest frequency in the world) I will be resorting to the Global 25 PCA courtesy of the eurogenes blog and examine samples going all the way from Bronze age to Medieval times.

Chalcolithic/Early Bronze Age

While the G25 is not perfect for mapping NW euro variation
it does a damn fine job of playing out this bronze age
drift.

Middle Bronze Age

MBA samples from Ireland/Wales not available but gradually
the distances to moderns become lower as local neolithic
holdouts are absorbed into the overall population.

Late Bronze Age

Before arrival of Brythonics with Hallstatt C culture.

Iron Age

After arrival of Brythonics there is noticeable increase in EEF.
Even slightly more than modern Irish surprisingly hence the 
higher distance than Scotland_LBA. 
Surely after the arrival of Anglo-Saxons and Vikangs
this close drift with Irish ends?

Early Medieval

Picts narrowly plot closer to modern Scots but quite shockingly

the early medieval samples mostly taken from an 8-9th century

grave from Hinxton, Cambridgeshire plot 

nearest to Irish again so they are heavily intermingled 

with assimilated Brythonics. This would seem to 

indicate that modern Anglos require extra "Southern" drift

that likely arrived from France during the high medieval

era due to the close relations Plantagenets had with French

nobility.

  

Last year's Viking burial paper Sikora et al 2020 goes into this southern drift which I have suspected for some time in the supplementary materials note 11:

"A major 2020 study, which used DNA from Viking-era burials in various regions across Europe, found that modern English samples showed nearly equal contributions from a native British "North Atlantic" population and a Danish-like population. While much of the latter signature was attributed to the earlier settlement of the Anglo-Saxons, it was calculated that up to 6% of it could have come from Danish Vikings, with a further 4% contribution from a Norwegian-like source representing the Norwegian Vikings. The study also found an average 18% admixture from a source further south in Europe, which was interpreted as reflecting the legacy of French migration under the Normans."

18% seems bang on but this turnover did not come from 
Normans themselves who were largely an elite, but rather
from Gascony which was an English possession for centuries
even to the point medieval French chroniclers considered them
to be "Anglais".

"Oui oui vee ar caming vor vour vimmin Haroldus"

Taking an average of all Irish/British bronze age 
samples available on G25 we get what I feel is a 
reasonably accurate picture of where this continuity is highest
My thanks to ancestral whispers for the map and reconstruction of
Rathlin 1, pictured on the left. 
Although there are only two Irish BA samples available
currently so the overwhelming majority of these samples are from
Britain.