by Conrad W. Terrill, 29 Mar. 2010
This occasionally updated article sums up our current YDNA results for descendants of Roger Terrill. "Modal Roger1" is our determination of Roger's YDNA, based on the modal (the most frequently occurring) value for each marker.
View the chart: (the complete set of results)
(Click here for an explanation of the chart)
New developments since the last update:
1) Alan Turrill's 61 to 67 marker panel results came in, with the results assumed in the last update.
2) Casey Terrell, a descendant of a Benjamin Franklin Terrell b. ~1827 in Kentucky, who married a Mary McAlister, joined our group from the Terrell Surname Project. He's been tested to 67 markers.
3) Richard Terrill, a descendant of Samuel2, has joined our group and been tested to 67 markers.
RRTyrrel is Bob Tyrrel, Nancy Tyrrel Theodore's brother, a decendant of John2 (John2 + 9 generations).
RTerrill (2) is Richard Terrill, a descendant of Samuel2 (Samuel2 + 8).
CWTerrill is me, Conrad Terrill, a descendant of Thomas2 (Thomas2 + 10).
JRTerrill is Murph Terrill, a descendant of Thomas2 (+ 8).
WD Terrill is Bill Terrill, a descendant of Thomas2 (+ 10).
ASTurrill is Alan Turrill, a descendant of Daniel2 (Daniel2 + 10).
TMRoberts is Tom Roberts, a descendant of Daniel2 (+ 9).
CMTerrell is Casey Terrell, who does not yet know his descent from Roger1.
RTerrill is Richard Terrill, of Lincolnshire, England, who we doubt is descended from Roger1.
What have we learned so far? Roger Terrill's hypothetical yDNA results, to 67 markers, are now very well established. The latest new results, for a descendant of Samuel2, fall right into place. We have results now for descendants of John2, Samuel2, Thomas2 and Daniel2—all but Roger2, of the sons of Roger1 who propagated his line. We've also established 67-marker results for Thomas2 and Daniel2, but those for John2 are questionable for two markers, and those for Samuel2 are questionable for one marker. We actually have an indicator for the Thomas2 line, since his yDNA had a mutation in marker CDYb (a value of 39 as opposed to 40). Since Daniel2's hypothetical results match those of Roger1, there is no indicator for his line. We don't yet know if there are indicators for John2's and Samuel2's lines. For John2's line the two possible indicator mutations are at markers DYS 448 and DYS 456. The probability is 19% that one of these will serve as an indicator (see "All the nitty gritty" for more detail). For Samuel2's line the one possible indicator mutation is at marker DYS 576, and the probability is 11.1% that this will serve as an indicator. To know for sure, in the case of John2's line, we would need a test sample for a descendant who is not descended from John2's son Josiah3. For Samuel2's line we would need a test sample for a descendant who is not descended from Samuel2's son Adam3. For all the sons' descendant trees there will be mutation indicators for certain branches, which we will learn more about as more people get tested.
Of the six of us who have been tested to 67 markers, two show three mutations since Roger1, one shows two, two show one, and, if Casey Terrell proves to be a descendant of Roger1, as we expect, he would be the first to show none at all. So, we're beginning to see, vaguely, what distribution to expect. We might find a descendant with four mutations in his line, but it seems rather unlikely that we would see more, in the near future. And we see that it is possible for a line to propagate ten generations or so without any mutations at all. We're hoping to be able to link to the ancestry of Richard Terrill of England, who is not a descendant of Roger1. His 67-marker results show three deviations from Modal Roger1. It's fairly hard to say, based on what we now know, how far back his and our most recent common ancestor lived. It's also proving very difficult to trace his ancestry back earlier than the late 1700s, but we'll keep trying. By the way, Richard has the same CDYb mutation that marks our Thomas2 line, but we seriously doubt that he can be a descendant of Thomas2. I asked about this anomaly at a Genetic Genealogists of Northern Virginia meeting this past month, and was told by the chairman, Jim Logan, that CDYb has a reputation as a rapidly-mutating, erratic marker. So we suppose that it has happened by chance here that two different lines from a common ancestor show the same mutation.
(See Obsolete Articles for old versions of this article.)