[extropy-chat] evolution / selection of cells within a single body / lifespan

[Ensel Sharon]

Hello,

On Thu, 26 Oct 2006, The Avantguardian wrote:

> > I am very interested in learning more about the
> > concept of cells or
> > mitochondria evolving, or facing selection pressure,
> > within a single body,
> > and within a single human lifespan.


(snip)


> Although if you get bogged down in detail, the two
> forms of clonal selection may seem to differ but the
> general theme is the same. It is an evolutionary arms
> race going on between cells of the self, non-self
> cells (microbes), and defector cells within the
> context of a single organism's body during its life
> span.      
> 
> Other terms I have seen used in the literature
> specifically in regards to cancer cells are "somatic
> evolution" and "clonal evolution" which are more
> reflective of the constant Darwinian struggle going on
> within your body.
> 
> In no other way is the illusion of "you" made more
> apparent than when you learn that you are a collective
> of factions competing with one another as well as
> foreign invaders for the holy grail of another
> sunrise.
> In any case it is a facinating subject which certainly
> deserves a book.



I am interested in the topic, generally, but I was specifically thinking
about the "athletes paradox" as it relates to aging (how athletes produce
more metabolism, and consume more calories, but seem to gain the same
benefits as those practicing calorie reduction, among other things) ...
and it occurred to me that perhaps placing exercise stress on the body
produces a selection effect in the body - marginal cells that would
otherwise survive and promote decline in a non-stressed body get quickly
weeded out when the body is stressed, as in exercise.

Comments ?

If this were true, it would seem that exercise would need to be started
early in life _and_ maintained throughout life, or else you would end up
stressing cells/systems/genes that had already declined due to lack of
selection pressure.  This reminds me, of course, of the proposed theory
that CR only works when you begin young, and further, that CR is perhaps
just another form of stress on a bodily system ... perhaps fostering
intra-body selection.