"Tim Tyler"  wrote in message
news:bighgn$1bp3$1{at}darwin.ediacara.org...
> Anthony Cerrato  wrote:
>
> : The bottom line is, I think, practical limits on growth
> : ensure that no complex dynamic system can eternally
remain
> : poised on the edge of chaos, exploiting incoming
external
> : energy, without ultimately losing detailed morphological
and
> : functional integrity on all levels.
>
> Nothing's eternal - but those "negligible senescence"
cases
> are a bit inconvenient for any notion that nature can
> never repair the damage caused by aging.

I'd agree that nothing biological is _eternal_--pure matter
and/or
energy though may exist forever (though there is still a
chance that even the proton will be found to decay in
10^100+ years. :) ) Any form of _structured_ or _organized_
matter however I'm certain has a finite (even if long)
lifetime.

When I was a teenager, I thought there might possibly be a
small
chance immortality would somehow be discovered before I
died. Today I would accept even pseudo-immortality, but I
know there is no chance of that. I suspect in a few decades
we will be able to extend life to perhaps 120-159 years with
minimal aging using medical and pharmaceutical techniques
coupled with the use of simplistic gene modification and
stem cell techniques. But, while I think it will eventually
be possible, life extension to more than a thousand years
will take science thousands or millions of years of
research.  Ageing will still take a significant toll for
humans for millennia I fear.

> They might not be cases of zero senescence - but they are
> very, close.  The repair mechanisms evolution is capable
> of constructing are pretty fine tuned - to the point where
> we can hardly detect any resulting aging.

My problem with repair for humans is humans are much more
complex than trees, or for that matter, any other form of
life on the planet (taking into account the human brain.) My
previous speculations were based on ageing and death are a
result of breakdowns of (primarily biochemical and organ)
subsystems of the overall body system--also, the more
complex the organism, the more subsystems there are to break
down, leading to irreversibly unrepairable functions. The
profusion of biochemicals and their function is staggering,
and the number of things that can fail to work properly
enormous...this is a direct result of complexity, though I
would guess raw size and other factors are confounded in
organism lifespan also. BTW, in talking about lifespan I'm
disregarding organisms which reproduce by cloning since I
think lifespan has to be defined for the initial pre-cloned
organism only. A minor semantic complication.
.....tonyC
> --
> __________
>  |im |yler  http://timtyler.org/  tim{at}tt1.org
>
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