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

[The Avantguardian]

--- spike <spike66 at comcast.net> wrote:

> 
> > bounces at lists.extropy.org] On Behalf Of Ensel
> Sharon
> ...
> > ... 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) ...
> 
> This athlete's paradox does not seem paradoxical to
> my understanding of how
> CR improves health.  One benefit of both athleticism
> and CR is being thin.
> If one is thin, one does not waste one's limited
> supply of stem cells in the
> creation of useless and harmful flab, so there are
> more of them available
> for regenerating damaged tissues and for keeping one
> well.

Very perceptive and very correct, Spike. 

I would further add that exercising to much, too young
and or CR too young will both stunt ones growth. This
is exemplified by women marathon runners who lose
their menses while in training. (They usually get it
back, but there is a definite correlation between
surplus calories and fertility.)

In nematodes (heh I love that word) CR causes a dauer
form which is a variant phenotype that is sexually
immature but lives a long time. My advice is you are
never too old to either exercise or CR but you
definately can be too young.

The changes wrought in the body by both of these
methods are evolutionarily traits that originally
evolved to get organisms through tough times by
sacrificing fertility for survivability. (Did you know
if you fry a nematodes testis off with a laser, it
lives longer?)

While the dauer nematode can put their development on
hold to pick it up later, I don't think mammals can do
that. At least I wouldn't risk it.

It just goes to show that even in biology there are
hard choices and trade-offs for everything and no free
lunch to be had.
 
Also it may be worth noting that about a third of
papers that can be found by key word searching on
"athlete paradox" involve young healthy athletes
keeling over dead for no apparent reason. The rest are
about fatty acid metabolism and insulin sensitivity in
athletes versus obese diabetics. 

Stuart LaForge
alt email: stuart"AT"ucla.edu

"Believe nothing. No matter where you read it, or who said it, even if I have said it, unless it agrees with your own reason and your own common sense."- Siddhartha Guatama aka Buddha.


 
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