GENEALOGY-DNA-L ArchivesArchiver > GENEALOGY-DNA > 2003-11 > 1067798461
From: David Faux <>
Subject: Re: [DNA] Marker Mutation Rates
Date: Sun, 2 Nov 2003 10:41:03 -0800 (PST)
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.
By the way the article can be downloaded from the www.familytreedna.com site - then going to the "Library" section, and clicking on "Characteristics and Frequency of Germline Mutations at Microsatellite Loci from the human Y Chromosome, as Revealed by Direct Ovservation in Father/Son Pairs".
Art Staples <> wrote:
David, Well put, I agree with you.
I am sure that in time this will all be sorted out.
However, we have to be careful that corporate marketing zeal does not
Corporations promoting DNA testing have a big responsibility as their
integrity is on the line.
DNA data for "Surname Projects" can only be useful if there are vital
records available to prove who, where, and most important when an event took
place. If there are no vital records available we are dealing with "Family
Group Migration" not surnames.
DNA requires the same close scrutiny as any other conventional genealogical
source and both must be used together to prove a pedigree.
Regards, Art Staples
----- Original Message -----
From: "David Faux"
Sent: Saturday, November 01, 2003 4:14 PM
Subject: Re: [DNA] Marker Mutation Rates
> Hello Ron and all:
> I fear that the "MRCA" (0 to 800 years or some such figure to the most
recent common ancestor) concept and it's underpinning via "accepted"
mutation rates (e.g., .002 per marker per transmission or whatever) is
deeply woven into the thinking of most of us on the List. Actually I am of
the opinion that the whole conceptualization is flawed - and totally agree
with you. As a matter of fact I don't even give it a passing thought in my
surname and geographical surname studies.
> It is all guesswork, which can result in many false positives (assumption
that people share a common ancestor in a genealogically meaningful time
frame) and false negatives (assuming that two people are unrelated since
there is one too many mutation such as only a 22 of 25 marker match).
Studies of father to son transmissions indicate that mutations can occur at
any time, even two step mutations. This one observation creates chaos in
the concept of MRCA - which is based on probabilities and mathmatical
models. Models schmodels. Mutations can occur two at a time (how can you
known if it was 10 years ago or 1000 years ago - except via extensive
collection of data from as many people with the same surname as is
possible?). No one knows how many mutations are "back mutations". No one
can say with authority that just because two people match at 24/25 that it
is not merely coincidence and/or an example of convergent mutation. Cousins
sometimes "mismatch" by 3 mutations - wh!
> happens to their lines 400 years from now. Probably more mutations and
the conclusion that there is no relationship. The MRCA world is one of
extreme chaos - at least that is my conclusion. Even in the best case
scenario of decision making re whether two people are related, and when, the
plus or minus x number of years factor is so huge that at this point I have
dispensed with the matter entirely.
> In my case I have a distant "cousin" who is a one mismatch on a "slow
moving" marker, and a two step mismatch on a "fast moving" marker. My only
interest in the matter is to locate more family members to see if his
"signature" is closer to our common ancestor of 400 years ago, or whether my
line has better preserved the "original" haplotype. None of the calculators
or estimates is of any help whatsoever. A strong stance. Perhaps, but the
statistical MCRA estimates available are no better than guesswork, but have
the aura of "science" surrounding them.
> I hope that someone will step forward and offer a rebuttal to our take on
> David F.
> Ron Lindsay wrote:
> Greetings Genealogy-DNA List,
> Acknowledging the use of a small sample size (statistically a sin) to fan
> the flames coupled with what appears to be "factual" genealogical detail,
> continue to look for legitimate reasons to challenge the current thinking
> regarding the assumed Y-chromosome marker mutation rates.
> I would like to pose a question to the geneticists and mathematicians
> subscribing to this forum.
> Is it possible that a fallacy was introduced initially into the thinking
> regarding Y-chromosome marker mutation rates based in part on the fact
> marker mutations can move back and forth (+1 or -1) over time and was not
> properly taken into consideration by geneticists also using "limited"
> database sizes??
> Dr. David K. Faux, P.O. Box 192, Seal Beach, CA, 90740, USA
Dr. David K. Faux, P.O. Box 192, Seal Beach, CA, 90740, USA