From: Robert J. Bradbury (bradbury@aeiveos.com)
Date: Thu Sep 04 2003 - 14:01:24 MDT
On Thu, 4 Sep 2003, Kevin Freels wrote:
> [snip] --This doesn't bode well for the future of humanity. Especially since there
> is a tendency for the brood to feed back on itself and reproduce the same
> type of environment in their own offsping.
Not true, there are negative aspects -- consider HIV, West Nile Virus,
SARS, etc. that can have significant negative impacts. And then there
are things like Moore's Law, gradual advancements in birth control
technologies, declining economic costs (everything from cell phones
to food, in part due to biotech) and then eventually an evolution from
expert systems to AIs and nanotechnology that will have significant
positive impacts.
Its going to be tough to be sure -- but not impossible.
Look at my quote page:
"Impossible is a word that humans use far too often." -- 7 of 9
> Accumulating errors exceed the ability of
> repair systems to proofread fix them, even (to a lesser extent) the sex
> cells.
Yep, even though there are over 130 genes involved in DNA repair it
doesn't come close to what a typical Error Correcting Code can do
on a disk drive. And we know from Information Theory that we could
make this as reliable as we need to make it provided we have sufficient
information storage capacity.
> But this analysis, as we have seen, assumes part of what needs to be
> demonstrated - that older organisms automatically cease breeding reliably.
Its interesting that the processes are different (at least in mammals) --
in females its due to the gradual loss of the eggs she is born with --
in males it is likely to be due to the accumululation of mutations in
the sperm due to the continual cycles of cell replication that
sperm production requires.
> While that is contingently true of complex creatures, as we have just seen,
> what we need to ask is: why it should be so
Luck of the draw -- Nature hit on a system to mix up the genes perhaps
hundreds of millions of years ago and has just been executing variations
on a theme.
> Has this in fact been demonstrated? It would make sense.
Women go through menopause because they run out of eggs. Men contribute
to an increased genetic disease rate as they age. I also pointed out
several years ago on the list that something 70-80% of conceptions in
humans fail to produce a viable individual. The error rates are fairly
high and there seem to be systems that detect that and prevent the birth
of more people with genetic defects.
> It seems to me that nothing could be reproduced perfectly every time.
Information theory says that if you are willing to have enough redundancy
you can reproduce perfectly (within constraints of the information storage
capacity at your disposal).
> It would require perfection which I don;t think is natural.
Tell that to Deinococcus radiodurans -- the bacteria that can withstand
a megarad of chromosome breaking radiation that would kill human cells
many times over.
> Perfection, not being necessary to reproduction, does not exist.
Ah, but to Nature "perfection" is both mutation and selection.
If one didn't have both one wouldn't get variations on a theme
that produce better adapted organisms.
> So if you take uncorrectable errors as a natural part of life, it would only
> make sense that older organisms fail to reproduce reliably over time.
Aubrey, Rafal and I have discussed this at various times -- sometimes onlist --
sometimes off. It looks like there may be variable control of mutation rates
with perhaps germ cells << stem cells << differentiated cells. This has not
been proven to my knowledge. It may be related to the activity levels of the
cells.
> "Why, after all, shouldn't the machinery of the body's maintenance systems
> keep working at peak efficiency forever? The accepted answer is that there
> are better strategic trade-offs for available energy and coding, trade-offs
> that allow the old to wear out and die."
This is perhaps true -- it may explain the whole phenomena of caloric
restriction and lifespan extension. The bottom line from my observations
is that it is very hard to get a "perfect" repair system.
> The accepted answer may be close to correct, but I think it is much simpler.
> Nature simply doesn't have a goal. [snip]
Not true -- the goal is to evolve organisms that are better able to survive
and adapt to changing environments. To do that without 'intelligent design'
one has to accept some flaws and negative consequences in the process.
Robert
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