Text 450, 82 rader
Skriven 2004-10-21 09:48:00 av Peter F (1:278/230)
Ärende: Re: decrepitude
=======================



"Name And Address Supplied" <name_and_address_supplied@hotmail.com> wrote in
message news:cl65sp$b2n$1@darwin.ediacara.org...
> "Peter F" <fell_trapforspambot_in@ozemail.com.au> wrote in message
news:<cks1qv$f4h$1@darwin.ediacara.org>...
> > "Name And Address Supplied" <name_and_address_supplied@hotmail.com> wrote
in message news:ckn2id$1v19$1@darwin.ediacara.org...
> > > "Peter F" <fell_trapforspambot_in@ozemail.com.au> wrote in message
news:<ckjj1c$spu$1@darwin.ediacara.org>...
> > > > "Elaine Jackson" <elainejackson7355@home.com> wrote in message
news:ckhf8a$95v$1@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?

For the probability of a species' or population's persistence as such -
subjectivity does not come into it. 

> 
> > 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. 

Good that you agree! (But where did the "On the contrary" come form? ;)

> The interesting
> question is whether such a disadvantage can outweigh the immediate
> individual advantage of longevity. I doubt that it can, in general.
> 

I know that a subject for discussion that deals with death is difficult right
down to how we are designed by what is naturally written in DNA. Even so, I
think you ought to be able to doubt this doubt of yours.

P
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