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Archiver > GENEALOGY-DNA > 2005-01 > 1105651991


From: Charles <>
Subject: [DNA] Male Line Specific Y-STR Average Mutation Rates
Date: Thu, 13 Jan 2005 16:33:17 -0500
References: <41E5775C.7060302@kerchner.com> <REME20050112155719@alum.mit.edu> <41E59CA9.4020303@kerchner.com> <REME20050112183553@alum.mit.edu> <41E5BBC9.8020603@kerchner.com> <REME20050112203830@alum.mit.edu> <41E5DB49.7020206@kerchner.com> <REME20050112224525@alum.mit.edu> <41E60555.1080203@kerchner.com> <REME20050113143016@alum.mit.edu>
In-Reply-To: <REME20050113143016@alum.mit.edu>


John,

You keep focusing on the average and tend to always minimize the
differences observed between one male line surname project (y chromosome
observed average mutation rate) compared to another. But clearly some
surname projects are observing average mutation rates 3 or almost 4
times more than others. This has been discussed off and on in this List
over the past year or so, as now and again various surname project
administrators ask questions about mutation rates for their projects.
Usually when this happens, and you and a few others keep dismissing it
as statistically insignificant and/or anecdotal as compared to the
commonly used .002 historical average Y-STR mutation rate. You keep
wanting to hold onto that historical average as the gospel for some
reason, when that overall average itself is based on limited studies of
a limited number of Y-STR markers years ago and is itself the subject of
debate and is no longer used by several testing companies as the correct
overall average. FamilyTreeDNA's study early released curve at the Texas
conference shows that Y-STR markers vary considerably from marker to
marker, although they did not tell us which marker is the slowest and
which is the fastest and the respective average mutation rate for each.
They are waiting to formally publish to release that.

In addition to average rates varying from marker to marker, I believe
the average mutation rates will also be shown to vary from male line to
male line. I believe there is an underlying reason related to the male
line Y chromosome Y-STR replication/copying process in each male line
which results in a different Y-STR average haplotype mutation rate in
one male line compared to another. Thus I think it is important for the
surname project coordinators to think about this suggestion and
calculate their projects observed average mutation rate and use that in
analyzing their project data when comparing things such as Genetic
Distance between individual project participants, as opposed to the one
size fits all, historically based, .002 Y-STR average mutation rate.

It makes me think of an analogy using shoe sizes. Shoe size varies
considerably for the population as a whole. But they also tend to run
larger or smaller on average in some family lines. Since this analogy is
being used to discuss male line Y chromosomes we'll leave the ladies
shoe sizes out of this one. One can calculate an average shoe size for
the whole population of males or for a single family male line. And even
though all those calculated averages for the various families will fit
into the normal curve for the data, and the uncertainty estimates for
the calculation, .... there are still very different shoe size averages
in some families compared to others. We don't try to make everyone fit
into the same shoe size, or dismiss shoe size variations as
insignificant in the real world, simply because we know the shoe size
average for the population and the uncertainty of the shoe size average
data calculation, and that the math and statistics say it is within a
normal distribution and thus statistically insignificant. If one male
line wears a size of 13, they are still within the normal distribution
curve for shoe sizes overall. But their shoe size in the real world is
still significantly different from the overall population average and
other male families where the shoe size may average 9 in that family.
When a man walks into a shoe store and puts his feet up to be measured,
and he's got a size 13 shoe, the salesman doesn't say -- well look at
that, just another the statistically insignificant shoe size.

A Y-STR haplotype average mutation rate which is .0015 in one male line
is very different than a Y-STR haplotype average mutation rate of .0056
in another male line. Sure they all fit under the normal distribution
curve for the data and the uncertainty for the calculation. But in the
real world they are very different none the less.

My Log will collect a lot more data. I will start plotting a histogram
once we get enough data in the Log. Whit is also going to do
calculations. A year from now we will see what the data suggests and how
wide and flat the normal distribution curve is, or is not. You can
criticize the early data in the Log, and from the comments of various
project administrators in this List, as statistically insignificant or
anecdotal at this point. But I am going to pursue this none the less. I
will let the collection of more data in my Log and the passing of more
time tell the story. Just like I did with my DNAPrint Log. But I think
you are dismissing the observations of various project administrators
too arbitrarily when they report their data and you say to them that an
observed average mutation rate in one family of .0056 is not
significantly different from one which average .0015. Only a
statistician would say that. Of course the range of variations is still
within the probable normal distribution curve, but they definitely are
very different. And I am going to document those difference via my Log
for the benefit of all.

One size does not fit all in shoes and I believe one size does not fit
all family surname projects when it comes to the Y-STR haplotype average
mutation rates.

I invite you John to share your data and make an entry into the Log.
Link to the Log is below.

And as many have stated about my other Logs, the comments in the Log
make interesting reading too. Synergy at Work!

Charles Kerchner
http://www.kerchner.com/cgi-kerchner/ystrmutationrate.cgi
http://www.kerchner.com/dnamutationrates.htm
http://www.kerchner.com/dna-info.htm


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