On May 18, 2011 8:46 PM, "bmolloy" <[EMAIL PROTECTED]> wrote:
>
> Greetings all,
> Re whales "choosing" to return to the sea.
wow, i'm surprised a little by the reaction that proposition is getting.
The statement seems
> to turn natural selection on its head.
i don't think so.
>My understanding of evolution is that
> it's a question of adapt or die out.
this is an over-simplification.
>As the environment changes the more
> adaptable in a species live and thus reproduce ever more adaptable
> offspring, while those that fail simply die off.
this may well be one way that evolution occurs. almost certainly. but why
couldn't a mutation occur which enables a creature to occupy a *new* niche,
absent environmental pressure.
> The changes are totally random, due to the chromosome scatter which occurs
> with each birth i.e no offspring is an exact copy of its parent, hence
each
> is a mutation of some degree. Some of this mutation is adaptable, some
> irrelevant, some not and some harmful.
> If the mutation increases survivability in a changing environment the
> possessor will survive to produce more offspring with similar mutational
> trends. In this way we have species change. . .
hmm. again, this over-simplifies things. in fact, i would suggest that it
inverts evolution as much as anything i've said.
many, if not most species occupy specific niches, living off a narrow
spectrum of foods. sometimes a single, specific thing. how does that
square with "survival of the 'fittest'"? does it represent an evolutionary
cul de sac? or a choice?
> The changes are incremental and often miniscule, occurring on time scales
of
> hundreds of thousands and even millions of years, hence the outcome surely
> cannot be attributed to choice.
not necessarily. in fact, the indications seem to be that very significant
mutations can occur over much shorter timescales than what has been the
conventional wisdom. which makes total sense IMO, because otherwise certain
evolutionary changes become very hard to explain.
for example, take the original proto-air breathers. those fish that had
both gills and primitive lungs. where did those lungs come from? was there
a tortuous process akin to ptolemy's planetary orbits, whereby these
different tissues developed independently, to finally, in one last
incremental mutation, become linked as a whole respiratory system? or
instead, maybe there once was a little fish fetus with a mutation in its
"switching" genes such that it remained in one growth phase longer than
usual.
regardless, we now have this fish that can obtain oxygen from the atmosphere
as well as from water. plus these funky, overgrown fins. why does it
ultimately leave the water? does it *have to* be that it did so out of
necessity? or perhaps simply because it could? because it chose to?
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