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Archiver > GENEALOGY-DNA > 2005-09 > 1125611507


From: "Eric Olson" <>
Subject: Re: [DNA] In Chimpanzee DNA, Signs of Y Chromosome's Evolution.
Date: Thu, 1 Sep 2005 14:51:47 -0700
References: <43175294.7010002@comcast.net>


Sperm competition? I am suppressing a desire to relate a crude joke.

But really, what does happen when a Y-DNA STR variance or mutation takes
hold and is successfully transmitted to a son? Surely given the very large
number of sperm produced constantly by a male, it can be reasonably posited
that many, perhaps thousands, of such "mutations" are occuring daily, all
the time, in all men, either by "slippage", environmental assault, or other
unidentified mechanisms.

Yet it is only one out of billions that will successfully fertilize an egg.
The chances of a mutant variety of Y-DNA in a sperm actually fertilizing an
egg is therefore vanishingly small, but non-zero, given all the sperm
competition, and most Y-DNA mutations do not get transmitted and expressed.
This may be similar to the so-called founders effect when there is a
successful male offspring carrying the changed Y-DNA. It would be a random
and rare occurance, but once happened, became amplified.

We might therefore expect to see cases where only one son's descendants of a
father passing on the changed "junk" Y-DNA, while the other sons descendants
match with their father's unchanged Y-DNA. Has this been observed?

Eric Olson



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