X-Message-Number: 12821
From: "John Clark" <>
Subject: Evolution and Long Life
Date: Tue, 23 Nov 1999 09:43:23 -0500

    >>Me:

    >>long life for mice would be an evolutionary advantage and the advantage is
        >>obvious, it just isn't very big;

Rand Simberg <> in #12816 Wrote:

    >I guess it's not obvious to me, at least from the standpoint of the gene.
    >Can you enlighten me?

All else being equal a long lived mouse would have more opportunity to mate
and pass on more genes to another generation than his short lived cousin,
but in the real would all else is not equal. It takes energy to keep in good
running order for a long time and you'll probably be eaten by a cat before
you get very old anyway, so the advantage is not great. Mouse genes have
found that the best strategy for increasing their number is to put all their
effort into a mouse's early days, so they created a vehicle that grows fast,
reproduces a lot, and dies young. If this was not true the p66 gene would
never have evolved in the first place.

To live longer a mouse does not need to evolve new genes, it just needs to drop

a gene it already has, however evolution has chosen not to do this. Evolution 
not

only evolved this life shorting gene it retained it for millions of years, that 
means
mutations that rendered p66 inoperable (and this must have happened often as it

does in all genes) did not do well in competition with non mutated working 
versions
of p66. Hence the speculation about the downside of the genetically engineered
Methuselah mice, speculation that p66 must somehow increase the fertility rates
of young mice.

                    John K Clark       

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