I guess the whole world knows that King Richard III’s skeleton has been found in Leicester. Two things about it particularly interested me.
The first was that the person whose drive brought about the discovery, Pippa Langley, turnes out to be an acquiantance of my brother, much to his surprise. The second, of more general application, was the announcement that there was a DNA match between the bones and a descendant of Richard’s sister.
How much DNA counts as a match, I wonder? I ask because if we assume the sister in question to have been born around 1450, we can estimate that there have elapsed perhaps 25 generations leading to the lucky heir. And that means he has 2^25, or 33,554,432 ancestors of that generation. Or to put it another way, statistically it is likely that a majority of the indigenous population of Britain is also descended from Mary’s sister to the same extent.
Unless, of course, that particular line kept on marrying their siblings.
Jon, I think the DNA connection was based on analysis of mitochondrial DNA, since they traced it from his sister. Of course Richard himself has no mito DNA descendants, since it is only passed through the mother. This is typical for ancient DNA analysis, because the increased copy number of mito DNA makes it easier technically to analyze the kind of degraded sample they would get. (There has been some success recently in analyzing Y chromosome markers in ancient DNA, but I gather that it is iffier.) I think the match means that there was an identical or very similar pattern of short tandem repeat markers in the two samples. I say very similar because STRs could have a mutation or two when centuries separate two related samples – the mutation rate at STRs is higher than for single nucleotide variants.
Thanks, pngarrison, and welcome to the site – though you’re a familiar face from BioLogos.
Id wondered if mitochondrial DNA was the marker, but have never been sure of how male offspring relate to its matrilinear transmission. The match was a male descendant – does that mean I have my mothers mitochondrial DNA, though its only inherited through the matrilinear route?
Jon, I broke Rule #1. (“When you don’t really know, keep your mouth shut.”) I have read more about Y chromosome analysis than mitochondrial and I made an unwarranted generalization. STRs on nuclear chromosomes are analyzed for detection of close relationships, as in genetic genealogy, but apparently not in mitochondrial DNA. Everything I see described there is apparently single nucleotide variations or short indels.
Oh, and yes to your question. We males get our mito DNA from our mothers, but we don’t pass it on.
If geneticists get it wrong, what hope for the rest of us?!
I was going to praise the genealogists for managing to trace a distaff line for 550 years – not easy, as I know from experience – even, I suspect if your ancestors are all toffs.
So are you saying they used mitochondrial DNA but that your detailed description was wrong (which is no big deal to us laypersons) or that they probably made the match from autosomal DNA, in which case my OP may have made a valid point?
… And thanks for the info. I shall blame my wife for any of my kids’ mitochondrial character faults!
Yes, you are right that that far back one has a huge number of ancestors, but I would guess that the genealogists probably did trace matrilineal descent from Richard’s sister to find the descendent. So mito DNA analysis would be some evidence that they had the right bones. I guess people keep track of descent from a kingly line, despite the fact that after enough generations, it doesn’t really mean much.