"Peter F"  wrote in
message news:...
> "Name And Address Supplied"
 wrote in message
news:ckn2id$1v19$1{at}darwin.ediacara.org...
> > "Peter F" 
wrote in message news:...
> > > "Elaine Jackson"
 wrote in message
news:ckhf8a$95v$1{at}darwin.ediacara.org...
> > > > >From an evolutionary standpoint, how does one
explain decrepitude?
> > > > 
> > > 
> > > There exists an evolutionary pressure that require that dads
(and mums) drop 
> > > off before they drain the environmental resources of their
descendants to 
> > > such an extent that the entire dynasty dies out. 
> > 
> > That's a strong statement, and one which I find implausible. I'd be
> > interested in seeing a (closed) model which favours such 
> > adaptations.
> > 
> 
> 
> There surely exists for any species an optimal population size range,
> or even just a possible population size range - one that in many cases 
> can not be maintained entirely by natural culling by deaths through 
> accidents and predation. 

"Optimal" for whom, exactly?

> Just wait and see how far we wealthy/high-tech humans can push our 
> desire for an extended life-spann without serious repercussions.! ;-)

Arguably we are already there in some parts of the world. But natural
selection doesn't give a damn about such nasty repercussions. Recall
the Hawk invading the population of Doves . . .

> Also, there ought to be a lesson to be learn from the need for recycling
> within a local (sufficiently closed) habitat. 

As I said, I remain to be convinced. 

> Death most likely became biochemically (genetically) programmed in at 
> an early period of our phylogeny. 
> 
> It is impossible to imagine any selective (longterm lineage-extending) 
> advantage possessed by to us ancestral populations that consisted of
> immortal individuals whose habitat were isolated (for periods of several
> generations) pools or primordial puddles {literally) of some nutritious
> soup {figuratively).

On the contrary, probably there is a selective disadvantage for such
immortality in terms of the success of the group. The interesting
question is whether such a disadvantage can outweigh the immediate
individual advantage of longevity. I doubt that it can, in general.
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