On Mon, 3 Apr 2000 06:43:16 -0400, gordon <[log in to unmask]> wrote:

>Amadeus, what you are saying here is true but I think that evolutionary
>terms it applies more to the future of humanity than to its present or
past.
>I think you are ignoring the fact that our current DNA is the product of
>billions of years of evolution.it did not suddenly come into existence at
>the beginning of the paleolithic. The changes to our genetic code in the
>last 40 thousand years are probably almost negligent when viewed in terms
>of the greater scheme of evolution.
>

What the DNA encodes, contains actually a "die now" factor, for several
cell types differently. For example human skin cells replicate only about
50 times in a lifetime. Most skin cell generations are already used up
by the age of 13 or 17 or so... and at some time there will be no more skin
cells having the ability to split. This is the (main?) genetic factor
that "ends" life at some day.
Seemingly it is of advantage that old generations die off at some day
to allow the new generations - which carry a new and potentially more
successful genome- to take their place.

I agree with what you said about changes in the genome. It's very slow.
If you recall - i argued, that most of our genome will have formed in
ages much older than even paleolithicum. In primates' evolving times.
Dependency on vitamin C (as only primates and very view animals show)
could have evolved, in my opinion, only in an environment where the
regularly vitamin C supply was so constant and high than body's
synthetisation wasn't used for *very many* generations.

>The best evidence that mother nature begins to care less for us after
>middle age is that we begin to fall apart physically.
>If natural selection did not
>in actuality disfavor old humans vs young humans then we would not lose our
>vision and our teeth as we grow old.

Yes, obviosly there are ageing symptoms which may come from some
wearing off or dying off of systems which aren't designed to be replaced.
Brain cells and teeth. And the genetic determined replication counter.

Still the genetic determined death can keep humans living (and working
with their database brains) up to very old ages.
As my grandmother, who died in the age of 95 or my friend , the
blacksmith, who continues working as a smith at the age of 89.

Did/do they have an extended replication counter evolved?
I think it's more, that certain ways of living cause less cell deaths.
Cell deaths are the genetic age-limiting factor.
So essential life sustaining systems can survive longer.

Anyway, besides medicine - which only cures acute problems -
humans have managed to extend useful lifespans much over the
35-40 years necessary to generate offspring.

Calorie restricted living may be a candidate, as has been discussed here.
But supplementation was not used for the two above.

regards

Amadeus