>Date: Sun, 11 Oct 1998 21:12:29 -0600
>To: asa@calvin.edu
>From: kbmill@ksu.edu (Keith B Miller)
>Subject: Re: Evolution is alive and well
>
[snipped, a discussion by Keith of Bob's points. I agree with Keith
but...]
then...
>Bob wrote:
>
>>Evolution has also generally failed to solve Mivart's dilemma, which
applies
>>to many transitions: "Natural selection is incompetent to account for
>>incipient stages of useful structures." How does natural selection
account
>>for myriad of incipient stages in the transition of terrestrial
mammals to
>>seagoing mammals, when those incipient stages decrease their current
>>adaptation to the land environment and do not increase their
adaptation to the
>>sea? I do not consider this a minor discrepancy. Gould has said that
>>Mivart's dilemma has never been resolved.
>
The dilemma of "origins" of potentially new body bits.
Keith's reply...
>The known transitional forms between mesonychids and whales, and
between
>varanid lizards and mosasaurs, are obviously quite well-adapted to
their
>niches. Since when are amphibious forms poorly adapted to their
>environments? Where exactly in these transitions to you see hopelessly
>unadaptive stages?
>
Keith, you haven't really answered the question. Transitions are known
and they say "life forms have changed over time", but I think Bob's
point is "what does Natural Selection etc. have to say about how new
organs etc. come into being?"
Personally I think this is a bit of an ask. What does it require to
answer? Imagine how a new organ might develop - lungs beginning as some
invagination along the alimentary canal. Where did that beginning begin?
What caused it?
As a Darwinian I'd say it began as some mutation in the developmental
process, and it gave its possessor some slight advantage, or was not
disadvantageous. Over time that was enough. Say a fish gulps air. At
first it uptakes gases via the blood vessels and somatic cells lining
its stomach. Any increase in area is advantageous, at first, but a
bigger stomach doesn't work as well. Instead a separate cavity is better
and over time and generations this increases in size and vascularisation
- ultimately creating a dizzying diversity of "lungs" amongst fish and
tetrapods. And some either lose lungs [chondrichtyans] or change them
into swim bladders [teleosts].
But where did that beginning come from? How? That'll always be the
question we can only hand wave about. Perhaps we'll be able to
manipulate developmental programs to change animals and plants and so
find out what's possible and what's not. However at present biologists
can only go from experience of variation of form and anatomy in living
creatures. It's a "mystery" because we can't know the exact causes, but
we do know that it happens and it happens today. That was enough for
Darwin and has been enough for countless others. Is it a mystery worth
scrapping Darwinism on, or is it just a blank in human knowledge and an
opportunity to learn more?
It's a big ask to say "answer this" because it's not really necessary to
the scientific study of evolution. Evolutionists must assume that
primordial "organs" etc. arise out of variations, but they don't need to
know how to ask useful questions about if evolution has happened. If we
assume that geology is accurate then we know that life has changed, and
much of the evidence supports evolution. Lots of blanks in knowledge
remain, but are they fatal? Fatal to pretensions of a "complete
world-view" maybe, but not to evolution as a scientific concept and
hypothesis generator.
Equally mysterious is why the ancestral animals took up new behaviours
that gave natural selection a handle on which to adapt them to a new way
of life and form. Why did the primal "shrew" begin leaping between
trees so that it might evolve into a bat? Why did those primal fish
start gulping air? And so on. Why? Perhaps God's involvement was more at
this level of "inspiration" of living things to try the novel and
extreme, to contribute to the creative process.
>Keith
>
>
>
>Keith B. Miller
>Department of Geology
>Kansas State University
>Manhattan, KS 66506
>kbmill@ksu.ksu.edu
>http://www-personal.ksu.edu/~kbmill/
>
>
>
Adam Crowl
PS
Also Keith, things are looking doubtful for the Mesonychid/Cetacean
link, because new Pakicetus skulls seem LESS derived than Mesonychids,
in their dentition chiefly. We might have to look for a new land-going
whale ancestor.
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