From: Ramez Naam (mez@apexnano.com)
Date: Thu Apr 03 2003 - 11:36:42 MST
From: BillK [mailto:bill@wkidston.freeserve.co.uk]
> My casual rephrasing of William R. Clark's abstract to the
> effect that antagonistic pleiotropy might not actually exist
> caused Ramez to leap to the defence of the concept.
>
> Clark's full text is at:
> http://www.wrclarkbooks.com/downloads/evolution.html
>
> What I think Clark is saying is that the senescence genes are
> built-in from the start.
I'd agree that there are genes which hasten aging but provide early
life survival advantages that have been conserved over at least a
billion years of years of evolution. The family of genes related to
the insulin and IGF-1 receptors, for example.
Indeed, this is what gives us good reason to believe that the same
genetic changes that have so greatly extended the lives of nematodes,
fruit flies, and mice will extend human life as well.
Yet we still have to marvel at the fact that these age-slowing
mutations never caught on in the wild, despite such a long period of
opportunity to do so. The answer is antagonistic pleiotropy - these
genes slow aging but come with disadvantages to survival or
reproductive success early in life. Evolution selects in favor of
early life advantages, and so the age-slowing alleles never have a
change to evolve.
mez
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