Metamorphosis - plausible evolutionary scenario?

Hello,

New to this newsgroup, so bear with me.

I've done due diligence as far as trying to find an answer to this
question (google searches, various FAQs, even a college library), but
couldn't, so at any rate please forgive me if this is some old
question that has been answered a million times before. Also, I must
say that in my search I did find a similar (but not exact) question
being posed on some yahoo group, but it was never answered; instead,
the posters told the guy that "he must have gotten the question from
some creationist website" because they said it was some old
creationist attack on evolution. I say all of that to say this: 1) I
am not a creationist, 2) I have not been to any creationist websites,
and 3) I did not get this question from creationists or intelligent
design people. I came up with this question, and this entire scenario
myself. If it turns out by chance that it really is some old
creationist attack, I apologize, and a quick link to a page or pages
which answer the question (or some reference for me to look at) will
be all I need.

Anyway, the question concerns organisms (insects, etc.) which undergo
holometabolism-type metamorphosis, with cell death (histolysis) and
regeneration (histogenisis). The question is how evolution and
natural selection could have produced such an organism. Evolution is
supposed to occur through small step-by-step changes. Changes which
are beneficial are passed down through natural selection. Changes
which are not are not. Now, let's take a prehistoric caterpillar
which currently does not undergo this sort of metamorphosis at all,
but through some mutation just acquires the very first step in the
chain - the ability to transform its body into a gelatinous mass and
die (it "dies" because it has not yet evolved the ability to further
transform itself into a butterfly - that's further down the
evolutionary chain). What is the evolutionary benefit that is being
realized at this point in time from turning into goo and dying (there
needs to be a benefit for natural selection to "select for" this
ability)? Furthermore, benefit or no benefit, how can evolution /
natural selection drive further change past the point at which the
organism evolves this ability to die? In other words, how can the
metabolism process further evolve *PAST* the stage of death to
eventually turn the caterpillar into a butterfly? It is no longer
reproducing at the point it hits this primitive metamorphosis (it is
dead), so assuming that this is a benefit at all (death), how is this
newly acquired change passed down (how is it selected for)? Passing
the change down requires reproduction, right? I suppose someone could
say it mated before it died. Fine, but if so, it is actually passing
down the benefit (death) before the benefit kicks in, so it seems
selection cannot select and thus play a role in the passing down of
the change because the thing it is selecting for (death) hasn't
happened yet.

(Also, as an aside, correct me if I am wrong, but the caterpillar is
not the entity which mates anyway, is it? That is the butterfly. It
seems this is a further problem. I suppose one scenario is that
caterpillars used to reproduce themselves, but lost the ability, which
was later gained in the butterfly?)

Anyway, one thing at a time. If anyone has anything plausible for me
to look at, let me know.

Thanks so much.
P.


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