GENEALOGY-DNA-L Archives

Archiver > GENEALOGY-DNA > 2003-11 > 1067839155


From: David Faux <>
Subject: RE: [DNA] Marker Mutation Rates [and MRCA]
Date: Sun, 2 Nov 2003 21:59:24 -0800 (PST)
In-Reply-To: <9C153D0B6A83DC4FA49E468EF360C7F5ECFB@ivey3.ivey-ivie-ivy.net>


Hello Jerry and all:

Yes, it was after reading your earlier post that I became more wary of mutation rate calculators and the like. None of these can say anything useful about individual cases. The best that can be offered is a probability statement - which has its place in population studies - but most on this list are genealogists.

Perhaps someone can illuminate why I should be jazzed to learn that the pattern of scores as reflected in a series of 3 mutations means that the Most Recent Common Ancestor (MRCA) of DKF and IAF is somewhere within the interval between present and 50 generations ago (at the 95% confidence interval). Gee, thats a whole lot of help.

I am also beginning to wonder whether some Y chromosomes (i.e., families) are likely to experience more mutations than others and if so, then any formulae may potentially apply to some families, but not to others. Irrespective, the fact is that a mutation could supposedly occur at any marker in any generation. It is even possible that in my family (for example) a mutation has occurred three times at a particular marker in the last 2000 years. What we need is a subset of markers known (from empirical evidence) to never mutate (for example there were no YCAIIa/b mutations in the Kayser study). If, then, my score on this marker differed from that of another fellow then there is virtually no chance we are at all related in the Y line. This would stop a lot of gnashing of teeth over whether a participant in a surname study is or is not related. It would also mean that my score and that of my ancestor 2000 years ago would be the same, and that if today this score is only fou!
nd among
(for example) the Saami, it would link me to this group (although a "die out" of those with this hypothetical score in other populations within the last 2000 years is theoretically possible).

Based on the Kayser evidence FTDNA should include DYS390 among their "fast moving" markers, and ultimately each marker used by each Y-DNA testing lab should be reported according to its mutation rate as determined by the available literature. Not that I would pay much attention - unless the rate was zero.

As it stands, neither mutation rates, nor the concept of the MRCA have any purpose whatsoever in my research. It would take a tremendous amount of refinement to convince me to take either seriously.

As ever, David F., the iconoclast.

"Jerry L. Ivey" <> wrote:
Please go back and review my previous posts about my cousin who has a
two-marker difference from me. It looks as if the change most likely
came from his grandfather (my g-grandfather) to him in two generations.

Low probability events can and do happen. They just don't happen very
often. :>)


-----Original Message-----
From: David Faux [mailto:]
Sent: Sunday, November 02, 2003 12:41 PM
To:
Subject: Re: [DNA] Marker Mutation Rates

A close inspection of Kayser's article on "Father/Son Pairs" provides
all sorts of insignts into why we should be wary of anything to do with
"mutation rate estimates". It is clear that each marker probably has a
rate unique unto itself, some seldom mutate, others rather frequently.
However, it seems that there are many who have accepted the dogma that,
for example, DYS390 is a very slowly mutating marker - so it is easy to
jump to the conclusion that two persons with different DYS390 scores are
not likely related within a time frame of genealogical interest -
especially if there are two other mutations.

It is DYS390 that is critical to my particular research. A person with
my surname who shares a common ancestor almost 400 years ago has a
"score" of 24, while I have 25. FTDNA for example includes this as a
"slow mutator" so if I took this "mutation rate" concept, as it now
stands, seriously then I would begin to wonder if the two of us were
related - since we also differ on one other marker (a two step
difference). Referring to the Kayser article it can be seen that DYS390
is the marker (among those measured) most likely to mutate in the
transmission between a father and a son. There were four such events,
two of them a "loss" and two of them a "gain" (but in the article
markers in general were more likely to mutate up than down). Thus I
don't know if the mutation in my case was a gain in my line or a loss in
my distant cousin's line. This is what I am actively exploring at the
moment.




Dr. David K. Faux, P.O. Box 192, Seal Beach, CA, 90740, USA



www.davidkfaux.org



This thread: