> 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.

There are quite a few different theories to explain the mechanics of aging,
actually, and yes that is one of them. By the way I am a member of the Life
Extension Foundation (www.lef.org) Longevity is really my primary area of
interest, and the reason that I decided to take more care and responsibility
for the foods I eat (and the supplements I take). My interest in life
extension is what brought NeanderThin and paleodieting to my attention.

> 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.

Right, yes you did argue that way. So I'm sure you understand that any
considerations about the social value of senior citizens are not very
relevant when estimating the extent to which natural selection favors their
existence. You and I know in our brains and in our hearts that old people
are valuable resources worthy of our support and appreciation here in the
world of modern social humans. Unfortunately our genetic code was for the
most part not created in the world of modern social humans. It has not had
much opportunity to adapt.

-gts