Friday, December 16, 2005

Ancient heroes and their Y chromosomes

Steve Sailer writes about some Irish and Scots mediaeval patriarchs and the remarkable number of their descendants. (He also mentions the case of Genghis Khan, who apparently had a huge number of descendants sharing his Y chromosome.) The implication is that these mediaeval patriarchs, one of whom gave his name to the Irish O'Neill family, were extraordinarily fecund.

I wonder if another way of looking at the success of these lineages is to consider that they may have been not so much unusually fecund, but geographically mobile. Genghis Khan certainly got around, ranging widely across Asia. Suppose he left sons all over this area, and they settled widely, attracting women to be with them. They could become locally dominant simply because they were settling relatively empty areas. That is, we might be dealing with a kind of "founder effect".

The Scots and Irish cases are somewhat similar, in that the locally dominant surnames and Y chromosomes are associated with out-of-the-way areas that might have been settled relatively late - Northwestern Ireland in one case and the Western Islands and Highlands of Scotland in the other.

Have a man settle a large new territory; breed several sons; let them take wives from outside on their travels and settle back in the large new territory. You would have plenty of space to live and breed, some initial outbreeding to avoid inbreeding, and the makings of a very prevalent Y chromosome. That is, the original man with the Y chromosome would not have had to be particularly fecund, provided his sons and grandsons were colonising a large new area.



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