Walt,
Let me give you a concrete illustration regarding the loss of a Y. My
maternal grandfather had three daughters. His Y was not passed on. My
paternal grandfather had two sons. The elder had a daughter and two sons,
one of whom died young. The surviiving son had one son (Keith) and three
daughters. The younger son had me and my sister. I have a son and
daughter, but my son has only one child, a girl. So, unless Keith has a
son, the Y from neither side will be passed down this line. If the Ys are
to continue to be passed down, it may be that one has to consider the
sibs of the grandparents. It is not a sure thing. Also note that it
doesn't have to be connected to fitness.
As to ancient practice, consider that it was common for a conqueror to
kill all the men and keep the women, although it was possible that all
the residents were massacred. An entire lineage could be lost quickly.
Dave
On Wed, 24 Apr 2002 19:11:19 -0400 Walter Hicks
<wallyshoes@mindspring.com> writes:
> Many thanks to Marcio and Glenn for the details of what these "first
> ancestors" mean. I still would like to pursue the mtDNA and
> Y-Chromosome
> a bit further if I might.
>
> Please let it be clear that I am not at all looking for a Biblical
> aspect of this area. I am simply interested in the evolutionary
> aspects.
>
> Sticking with the Y-chromosome: I see how genes in general can swap
> back
> and forth and how any given gene would have an ancestor back in the
> past
> somewhere. In the Y-chromosome it is easier to think about, if for
> no
> other reason than that it passes only from father to son and also
> the
> time scale seems so short!.
>
> Back some 100K years ago we have one man who has passed his
> chromosome to the entire human race. I wonder about the other
> humans
> who lived at that time. Certainly there were in the order of 100K
> men
> who had a different Y-chromosome. What happened to them? Apparently
> their descendents all died off. Would I expect that to be true? Heck
> no!
> --- unless they were genetically inferior. It seems really weird
> for
> that to have happened simply as a matter of course. In 100K years
> with
> an generally expanding population, I would expect the human race to
> have
> Y-chromosomes for many different sets of "Adams" back at that time
> in
> the not-so-distant-past.
>
> If you can bear with me, what is wrong with that reasoning?
>
>
>
> Walt
>
> ===================================
> Walt Hicks <wallyshoes@mindspring.com>
>
> In any consistent theory, there must
> exist true but not provable statements.
> (Godel's Theorem)
>
> You can only find the truth with logic
> If you have already found the truth
> without it. (G.K. Chesterton)
> ===================================
>
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