Re: Cornering the causes of aging

From: Robert J. Bradbury (
Date: Sun Jul 09 2000 - 15:58:39 MDT

On Sun, 9 Jul 2000, John Clark wrote:

> As for aging, it seems to me it's always a negative, it's just not negative
> enough for evolution to change.

Evolution will change the aging program as necessary to optimize reproductive
fitness. Ultimately however, it is very difficult for evolution to produce
non-aging organisms. Doing so requires that you sacrifice reproduction
resources for maintenance and repair producing lower fecundity. To
balance this, the non-aging organism has to produce ever increasing numbers
of offspring as it gets older (to maintain the fraction of longevity
enhancing genes in the gene pool). [Trees, sturgeon & lobsters for
example produce more seeds/eggs as the grow older and get larger.]
Eventually the individuals with the longevity promoting genes will
encounter the physical or resource limits of the environment (Trees
encounter the osmotic pressure water pumping limit on height while
animals encouter food limitations). You can't produce indefinite
longevity without an ever increasing fecundity which requires an
ever increasing resource base.

The net result of this is that it is difficult to impossible for
natural evolution to explore the phase space for genes or combinations
thereof that would produce indefinately lived species.

> A bug will probably get eaten within a year anyway so there's little point
> in maintaining the organism so well it could live longer than that, better
> to reduce the maintenance budget and increase the reproduction budget and
> have lots of offspring.

Yep, evolution has the emphasis first on the survival of the genes.


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