Branching of the subclades
fter the "8.2 kiloyear event", Isles AB (S2639)
washed up on the eastern shore of Britain. We know very little about the activities of Isles AB (S2639) after that. We know that they survived and perhaps even prospered.
After about 40 generations, subgroups formed. First Isles B emerged, then A. Later, Y3734
emerged from Isles B. From Y3734, Isles C and D emerged. Genetic calculations tell us when, but figuring out where takes a bit more.
The split of Isles A from Isles AB about 7 kya
may be the easiest to locate. There are virtually no Isles A outside the British Isles, therefore the branching of Isles A from S2639, about 5,200 years ago, occurred in Britain.
Isles A was not lucky. They apparently never fluorished and never dispersed. They apparently remained a small group, tightly located, probably in East Anglia. Then starting 2,000 years ago, multiple catastrophies over a 500 year span resulted in an extreme bottleneck
generating a TMRCA of only 950 years. Isles A, being located in East Anglia, would have been at the violent focus of the
as well as by being closest to the Plague of Justinian
, Antonine Plague
, Britain's Great Plague
, and other plagues
as well as the "AD 536 Events"
, and the
that almost finished them off.
By 600 AD, the total population of Isles A may have been in single digits, and perhaps as few as three families. One fled to the north, one to the area of Cork and Bantry Bay in Ireland, and one to southwest England. The first two have slowly multiplied. The one in Southwest England was eventually reduced to one single man. The family became extinct in England when he emmigrated to Virginia in 1635.
The split of Isles B from Isles AB: 7.2 kya
Branching of the subclades
Other Isles AB, having newly adopted the new benefits of the Neolithic Transition, began migrating inland, where Isles B
developed. Isles B was relatively successful early on (another indication of their use of neolithic methods) spreading throughout the British Isles. The TMRCA is about 5,370 years, which suggests a relatively tranquil existence.
Isles B ➤ Y3734: 6.5 kya
This was about the same time as the mesolithic-neolithic transition. Could it be that Y3734 carried the "secondary products revolution"
Y3734 ➤ Isles C: 5 kya
first branched off from Y3734 about 5,000 years ago. The distribution of Isles C in modern times seems split between Ireland and Great Britain with very few elsewhere, so it seems likely that Isles C emerged in the boundary area: Dal Riata
Y3734 ➤ Isles D: 4.3 kya
Y3734 went into Ireland between 6,500 and 4,300 years ago when Isles D was founded. We conclude that the founding was there because the modern distribution of Isles D is heavily weighted to Ireland especially near Rathcroghan.
Rathcroghan is a noted location for both Isles C and D, It was very successful and has extensive bronze age ruins, all of these during the same time period. This all seems more than just a coincidence.
The branching of Isles D from Y3734 was nearly simultaneous with the beginning of the
and with the domestication of the horse
Both Isles C and Isles D must have had some difficulties, not surprising among pioneers, with Isles C having a TMRCA of 2,730 years and D with a TMRCA of about 2,520 years. The eruption of Hekla 3
caused a bottleneck that might account for a significant portion of the shortening of the TMRCA.