"Ron Okimoto"  wrote in message
news:bhb21d$2n37$1{at}darwin.ediacara.org...
> r norman  wrote in message
news:...
> > On Tue, 12 Aug 2003 00:10:48 +0000 (UTC), "Alan Wright"
> >  wrote:
> >
> > >
> > >"dkomo"  wrote in message
> > >news:bh4fov$r8e$1{at}darwin.ediacara.org...
> > >> Ron Okimoto wrote:
> > >> >
> > >> > dkomo wrote:
> > >> >
> Snip:
[more snippage]
> In males the rate of transmitted mutations goes up with
aging.  They
> have most of the data on this using microsatellite data.
I haven't
> done it, but if you do a PubMed search using
"microsatellite and
> mutation rate" you will probably pull up some of these
papers.  It has
> been known for a very long time that chromosomal
abnormalities
> increase as the female humans get older.
>
> This is not the point at hand.  The point was that the
genetic
> variation of the population would tend to decrease as the
individuals
> remained reproductively active for longer and longer
periods.  This
> would be due to differential survival due to natural
selection and
> most of the oldest animals would tend to one most optimal
genotype.
> It doesn't have much to do with increased genetic
diversity due to
> aging.  The proposition was why not have immortals?
>
> There is the point that selection only works as far as the
horizon and
> if things are good enough you don't expect to select for
longer
> lifespans, but why slow the organism down?  Why not
maintain the body
> at its reproductive peak for as long as you can?  Why have
senescence
> factors?  The answer may be that populations can see
farther into the
> future than your horizon.  What we see in the current
species are the
> survivors of over 3 billion years of ecological upheaval
in the
> history of the earth.  Natural selection would be expected
to select
> for the survivors.  These survivors do not seem to include
organisms
> that can live and reproduce for as long as their genetic
structure
> would allow.

I basically agree with what you're saying, but isn't your
last sentence the most important point, not only in terms of
reproduction, but for the entire lifetime of any highly
complex organism viewed as a unified system. Genetic
structure allows reproduction (_and life itself_!) only
within restricted environmental bounds (even though we seem
to be finding more and more radical extremophiles everyday.)
However, we don't find
many simple organisms that have been selected to survive in
concentrated sulfuric acid or caustic, or in at least _very_
high energy radiation fields--complex organisms are even
more vulnerable in all respects in that more processes are
going on that can be interrupted/interfered with than
simpler organisms, and certainly with a higher probability
over a longer lifespan.

No physical laws can be violated for protoplasm, or anything
else for that matter, and entropy demands its toll
(protoplasm can't violate the law of gravity either, or
humans select for breathing in vacuum without a radical
re-engineering of their entire past evolutionary path.)
Accumulation errors in both function and structure accrue
slowly but continuously over time, and not solely in eggs,
sperm, and genomes. They finally totally exceed pre-evolved
correction/ compensation mechanisms and eventually must lead
to the death of the organism.

IMO therefore, there is only one way for humans to defeat
this "wearing-out" process for any arbitrarily long period,
and that is through a variety of medical procedures, drugs,
and particularly the use of new genetic or stem cell
bio-techniques to regenerate or replace aging organs and
other body structures.          ...tonyC

> Ron Okimoto
>
> Snip:-)
>
---
þ RIMEGate(tm)/RGXPost V1.14 at BBSWORLD * Info{at}bbsworld.com

---
 * RIMEGate(tm)V10.2áÿ* RelayNet(tm) NNTP Gateway * MoonDog BBS
 * RgateImp.MoonDog.BBS at 8/13/03 12:04:06 PM