Re: BBC News - Can we live longer?


Katt wrote:
> <rja.carnegie@xxxxxxxxxx> wrote in message
> news:1125059767.384732.16080@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
>
> >
> > But I presume you want to talk about evolution. If having more of this
> > gene makes you live longer, why hasn't evolution already given it to
> > us? Two or more copies of what previously was one gene is a very easy
> > mutation.
>
> We should remember, though, that evolution is not especially interested in
> how long we live after we cease reproducing: selection pressure favours more
> and earlier and more successful reproduction -- and giving you or me a long
> and happy retirement afterwards doesn't figure anywhere in the equation.

This begs the question, when and why do we cease reproducing? (At
which point the strict something-or-other-ist considers that we're
running on fumes.) Why shouldn't we stay fertile for longer? Or why
do we stay alive at all when we're infertile?

No doubt that's been discussed here before. For one thing, arguably
the body doesn't know it's infertile, although the menopause is one big
clue. But men don't even have that. Our fertility usually just fades
away gradually.

Other species tend to have regular episodes of fertility and
reproductive behaviour at long intervals, I think.

> In highly social species with slow maturation, there might be some selective
> advantage if grandparents live long enough to look after grandchildren; but
> it's gonna be finely balanced: grandparents consume more resources than tiny
> children do...

I wonder if we should consider the child literally carrying the
now-infertile parents and grandparents - or vice versa - as a metaphor
for one viable life-and-reproduction gamepiece (once it becomes mature
and finds a mate). Without adult care, the child won't live to
reproduce at all; it's worth keeping the grown-ups around for a while.
Society being what it is, that's probably mother and grandmother, while
the males go off looking for fertile, patient women to carry on their
strain.

.

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