This post could be the leadoff of a series called "incomplete genomics," in which I can't quite understand something which seems really fascinating. I'm just going to post what I have been able to figure out, and maybe later return and patch the beta version. Genetic Chaos blog
lists research papers related to genetic efforts to track historical and prehistoric human migrations. The topics are given a brief introduction, and the .pdf files are all there. Earlier this week, Havelock posted a whole set about the British Isles.
I was really intrigued by a paper trying to identify the genetic heritage of the current peoples speaking Celtic languages.
Several Celtic languages survive in the British Isles, but in the past there were many Celtic-speaking regions in continental Europe, including present-day Spain and northern Italy. Linguistic and archeological evidence have been cited in support of two opposing ideas about what happened between then and now. The earlier idea was that the Celtic nation had had its heartland in Central Europe (see Wikipedia here
) and that the Celts invaded the British Isles in several waves. A more recent suggestion (see also Wikipedia) has been that the Celtic culture developed in place along the Atlantic coast, with reasonable maritime cultural exchange, in an arc from Iberia to Norway.
Prior DNA tests of Irish and continental volunteers had given mixed results. A study of the Y-chromosome had shown an unusual haplotype known as R1b present in a high frequency in samples from both Pyrenees and the western British Isles, supporting the second model. But mitochondrial DNA (mtDNA) analyses did not given a clear readout.
The current paper
comes back with a much larger sample size- 8,533 individuals from 45 populations throughout continental Europe, and 200 Irish subjects. After quality control and sequencing of a specific segment of mtDNA, they measured the genetic distance (Phi-ST) among the mitochondrial sequences and then created a synthetic map of population relatedness placed on top of the actual map of Europe.
The result is that the larger dataset of mtDNA sequences now give a very similar picture to the earlier Y-chromosome results. Present day European genetic distances grade very smoothly across the continent from the Middle East to Basque country, with indeed an arc of very low genetic distance encompassing Northern Spain, Brittany, the British Isles, Iceland, and Norway. The authors furthermore arrive at qualitatively the same result by re-annotating published classical gene frequency analysis.
They conclude, then, that mtDNA and Y-chromosome data now agree that an arc of peoples share some genetic heritage. This in turn is taken to support the model that today's Celtic cultures developed in situ, and should possibly be renamed "Atlantic Celt" in distinction to the vanished continental Celtic peoples.
What I remain uncertain about is how the genetic distances map would have looked if earlier model was correct and the Celtic culture arrived in the British Isles by invasion. As Wikipedia
and my memory would have it, the old model of the Celts is one of being driven to the edge of the world by other tribes. Couldn't the current arc-like distribution of haplotypes also come to be if Celts fled their conquerors en masse?
UPDATE: I think I understand a bit better. In part of the paper they took many samples from east and west Ireland and could not find big genetic differences. The older Celtic model proposed that west Ireland was colonized by one wave and East Ireland by a subsequent wave.
Also, the Lepontic
people in Northern Italy, who are thought to have been Celts, were assimilated by the Romans without mass slaughter. If the Irish-originated-in-Germany model is correct, you might find a genetic connection with Ireland in the area around Lago di Como.
UPDATE: Via Boing boing
, Wales shall never be English.
Email correspondence, written in Welsh, gets mishandled by an English speaker. Worth a look....