Thursday, June 07, 2007

We're all royalty

Strange things come up in my online conversations, and this is one of the oddest in a while. A lot of people who do geneaology are thrilled to find that they are related to some noble somewhere, descended from Earl This or Queen That -- and apparently there is statistical evidence that this is probably true for everyone. Apparently, we're all descended from Charlemagne. Or Confucious. Or some poor peasant schlepping about in northern Germany in 300 CE.

A fairly recent notion in biology and genetics is the concept of Most Recent Common Ancestor (MRCA) ; that is, if you go back far enough, there is a common person in everyone's lineage. No, this is not a pitch for a "Genetic Eve" or any such nonesense, it's actually much simpler than that, and computer simulations have suggested that a common ancestor for ALL people of European descent is as recent as 1700 years ago.

Now, I'm the last person to try to explain statistics...they are mostly incomprehensible to me. But a statistician at Yale has apparently done a proof that points back to a common ancestor from about 800 CE. The logic goes something like this: everyone has two parents, four grandparents, 8 grandparents, get the picture. That number get really really big, really really fast. At some point, it surpasses the actual available population alive at the time everyones great-to-the-40th or whatever grandparents were alive. So, this means that people obviously shared ancestors. So far, so good.

At some point, the statistical count of people and relationships and time and DNA testing and whatever other magic mathematicians use converges on such a small group of people that everyone is somehow related to everyone else.

I get pretty fuzzy at this point. Lots of people have died, right? Not everyone has children, some people have more children than others, etc. But the math is sound, although even the statistician who did the paper admits that ht has probably overlooked a variable or two. But his conclusion? Everyone of European descent is related to Charlemagne -- a random choice of people living at the time that the MRCA existed, but a plausible choice, nonetheless.

Further study (by a gentleman named Mark Humphreys, a profressor a the Sschool of Computing at Dublin City University) has generated computer models that show that everyone in the world is eventually related to the Egyptian Royal house (1600 BCE), and other equally throught-provoking results.

I don't even claim to understand how they got to that conclusion, but if you want more information, here's the blog that I discovered this morning, and another explanation of how it's supposed to work.

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