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Archiver > GENEALOGY-DNA > 2006-01 > 1136406283


From: "Alfred A. Aburto Jr." <>
Subject: Re: [DNA] Y-STR Mutation rate
Date: Wed, 04 Jan 2006 12:29:13 -0800
References: <4.3.1.2.20060104144302.01fde180@mail.spacey.net>
In-Reply-To: <4.3.1.2.20060104144302.01fde180@mail.spacey.net>


> John E. Mellick wrote:

> List,
>
> Drew replied to Ken's note on Y-STR Mutation rate and added a clever
> story. Then Alfred replied to Drew's story
>
> Alfred wrote:
> Date: Wed, 04 Jan 2006 06:18:17 -0800
>
>> From: "Alfred A. Aburto Jr." <>
>> To:
>> Message-ID: <>
>> Subject: Re: [DNA] Y-STR Mutation rate
>> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>> Content-Transfer-Encoding: 7bit
>>
>> Drew Baumann Roberts wrote:
>>
>>> On 3 Jan 2006 at 17:11, Ken Nordtvedt wrote:
>>
>
> <snipped> (no pun intended)
>
>
>>>> How do the good mutations prevail? Greater
>>>> reproductive success of some mutational modifications leads to their
>>>> greater presence in future generations. Natural selection while being
>>>> a mathematical tautology is nevertheless profound and deeply robust as
>>>> a concept and mechanism.
>>>>
>>> Drew's Story:
>>> Suppose there lived a strong, central leader who cements bonds of
>>> fidelity
>>> and vasseldom by marrying many allied clan-daughters.
>>> He is given wives galore as a promise of loyalty and he is duty bound
>>> to produce Sons. <snipped again>
>>
>
> Ken Said,
>
>>>> Large regions of the dna material, especially in the Y chromosome, are
>>>> thought to be close to junk dna, not coding for anything important.
>>>> If so, their mutations should be neutral from a selection perspective.
>>>> Ken
>>>>
>>> Drew replied:
>>> Yet, the Y-chromosome, full of "junk dna", determines the sex of
>>> the fertilized egg.
>>>
>>> and finally, Alfred said:
>>
>> I think it is the "tips" or end-points of the Y-chromosome that
>> determines sex (that part of the Y that combines, and mixes, with the
>> X chromosome to determine maleness) --- the rest of the Y does not
>> combine or mix with the X and it has been called "Junk DNA" but I
>> think scientists are learning now that that may be a misnomer ---
>> the so-called "Junk DNA" may in fact play an important evolutionary
>> role in species. See for example: http://www.psrast.org/junkdna.htm
>> Al
>
>
[to snip or not to snip, that is the question ...]

> Now, I've put all this down to ask a question. ARE A MAN'S MUTATIONS
> FIXED AT BIRTH, OR DO THEY INCREASE AS HE AGES? This is a question
> I've often wondered, but haven't seen discussed. In the reference
> given by Al (just above) , titled:
> "Junk DNA" Over 95 percent of DNA has largely unknown function By Jaan
> Suurkula M.D.,
> states that "It has been reported that the sequences of this unknown
> DNA are inherited and that some repetitive patterns in it seem to be
> associated with increased risk for cancer. Also, the DNA has been
> found to mutate rapidly for example in response to cancer. " I read
> this statement to say that dna mutates when attacked by cancer. Is
> this true? Can a man have some cells in his body with different
> mutations than other cells?
>
> Then again, in the Jobling 2003 article "The Human Chromosome: an
> Evolutionary Marker Comes of Age" pg 4 states
> "Studies of genetic diseases show a strong bias towards fathers as
> the source of new mutations, and also show increasing mutation rate
> with paternal age (reviewed in REF. 12)."
>
> This statement indicates to me that ydna mutates more rapidly as the
> man ages. Is this correct? If so, I could see how a younger son
> might have mutations that an older son didn't receive, as the father
> aged. Is this an example of a "private snp"? If all of this is true,
> I would imagine that ancestral and derived mutations could be all
> mixed up?
>
> Someone please straighten me out on this.
>
> JohmM
> (Germany to America in 1728 >PA>NJ>IL>IA>KS>OK>FL)

I'm a neophyte in this area JohmM, but I think it is clear that in terms
of the Y-STR that mutations don't happen very often. That is, it takes
hundreds and thousands of father/son sample comparisons to see one event
(one mutation). So in ones lifetime, mutations in the Y-STR just don't
occur that frequently.

But mutations in general, over the entire genome, may increase with age.
I don't know really, just guessing that the longer we are exposed
(unshielded) to cosmic rays for example the more mutations will occur
... and, dang gum it(!), maybe that is why I'm more wrinkled now than in
my youth :-) I wonder if an experiment has been done on mice ... do
mice exposed to the open spaces have shorter lives (age quicker) than
those well shielded from cosmic rays?

Al

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