From: Robert J. Bradbury (bradbury@aeiveos.com)
Date: Sat Jun 07 2003 - 00:35:12 MDT
On Sat, 7 Jun 2003, Eliezer S. Yudkowsky wrote:
> Sorry, I have to side with the researchers on this one. The human body is
> designed, literally designed, to age. And you can't mess with that design
> until you know what the consequences are. Or you *won't* get old.
Actually, in a extremely rare case where I would object to a statement
Eliezer makes (I'm at times stupid but I'm not *that* stupid to do this
frequently), I have to object here.
The declining force of natural selection with age *cannot* allow an
organism to be "designed to age". The best you can manage is
a failure of the programs that keep the organism young.
Mammals started out as very small (bottom of the food chain) short-lived
organisms. Everything else in a mammalian genome should be viewed as
an "add-on" -- as we got bigger we had to develop better defenses
against cancer (e.g. telomere shortening) -- as our lives grew longer
we slowly moved from a R-selection reproductive strategy to a K-selection
reproductive strategy. During that process the genomes (in humans,
elephants and whales) adapted to "preserve" youth for as long as
was necessary (essentially until the hazard function dictated that
there was a high probability that the individual would have died from
"natural" causes).
There is no "program for aging" -- there is a "program which fails
to keep you young indefinitely". It is a subtle but significant
difference.
> Unshortening telomeres, immortality, are not just an incidental
> characteristic of cancer cells, they are the heart of the problem.
Not really. Endothelial cells and smooth muscle cells do not divide
*that* often -- so I suspect that long telomeres in such cells do
not present a significant risk -- muscle cells and to a lesser
extent endothelial cells do not generally become cancerous.
Now long telomeres in epithelial cells (skin, gut, etc.) --
now *those* I would be concerned about because they are constantly
dividing and are thus biased to become cancerous (in fact the
epithelial cells probably have some low levels of telomerase
activity to lengthen their telomeres).
> The human body was not designed to be easily revised for immortality. It's
> designed to burn out and die.
No, you cannot say it is "designed" that way. Its a lack of a sufficiently
robust design to *not* "burn out and die".
> Shortening telomeres prevents cancer when
> you're young, and that's pretty much all Nature cares about.
This is probably essentially correct.
> It is not the job of *these* researchers to untangle the problems of
> immortality. If they can give us small vessel grafts, good enough.
I would tend to agree here -- small vessel grafts could buy many people
perhaps decades -- enough to keep us going until the more robust technologies
kick in.
Robert
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