On Wed, 30 Apr 1997 20:38:39 -0400, Pim van Meurs wrote:
>TG>...Mike Behe presented a summary of his book as the opening
>statement. Harvard evolutionary theorist, David Haig, critiqued
>Behe's biochemical arguments, and Daniel Dennett, author of
>*Darwin's Dangerous Idea", responded on a slightly more
>philosophical level...
>SJ>Dennett...deludes himself by thinking that just because he
>thinks he can imagine a possible solution, then the "Mystery" is
>somehow "Solved". It sounds a bit like the medieval ontological
>argument for the existence of God - I can imagine there is a God,
>so there must be one!
PM>Sounds a bit like Behe, who deludes himself that irreducibly
>complex systems cannot have 'evolved'. Which is of course
>incorrect as has been shown.
No. Only *one* of Behe's cases was *possibly* "shown" not to be
irreducibly complex. There still are plenty more, including the
blood-clotting cascade and the bacterial flagella `electric motor'.
>SJ>This is a chilling warning of what would happen if Darwinist
>fundamentalists like Dennett or Dawkins came to power!
PM>Not nearly as chilling as if what Dennett feared most came to
>power. I hope that you were being sarcastic here.
I 've got news for you Pim. Christians *were* in "power" when
Darwinism arose and nothing remotely like what "Dennett feared most"
happened then. No creationist AFAIK has written of putting
evolutionists in cages and taking their children off them to be
taught creation, but "Dennett" has. One can only assume he means
it.
>SJ>Agreed. Darwinians have not shown *in any detailed way* how
>*all levels* of "living things" (in this case at the biomolecular
>level) "have arisen gradually by Darwinian natural selection".
PM>Sure, but that does not mean that they have not shown in detailed
>way how some level of things have arisen.
Big deal. *Everyone* accepts that "some level of things have
arisen...gradually by Darwinian natural selection". Even Creation-
Scientists accept micro-evolution by "Darwinian natural selection",
for example:
"Darwin's argument certainly seems logical. Is there any evidence that
Darwin was right? Can nature select as well as man? Answer: There
is considerable evidence that Darwin was indeed correct about natural
selection. Perhaps the best example of Darwinian selection is the one
that's in all the biology textbooks: the peppered moths." (Morris
H.M. & Parker G.E., "What is Creation Science?", 1987, p78)
>SJ>"The absence of fossil evidence for intermediary stages between major
>transitions in organic design, indeed our inability, even in our
>imagination, to construct functional intermediates in many cases, has
>been a persistent and nagging problem for gradualistic accounts of
>evolution. St. George Mivart (1871), Darwin's most cogent critic,
>referred to it as the dilemma of "the incipient stages of useful
>structures"-of what possible benefit to a reptile is two percent of a
>wing?" (Gould S.J., "Is a new and general theory of evolution
>emerging?", Paleobiology, vol. 6(1), January 1980, p127).
PM>And in 1994, to add to your quote collection, we have Stephen
>Jay Gould, writing of whales in _Natural History_ 5/94, pp.8-15:
>
>"... I am absolutely delighted to report that our usually
>recalcitrant fossil record has come through in exemplary
>fashion. During the past fifteen years, new discoveries in
>Africa and Pakistan have added greatly to our paleontological
>knowledge of the earliest history of whales. The embarrassment
>of past absence has been replaced by a bounty of new evidence -
>and by the sweetest series of transitional fossils an
>evolutionist could every hope to find. ... I don't mean to
>sound jaded or dogmatic, but Ambulocetus is so close to our
>expectation for a transitional form that its discovery could
>not provide a professional paleontologist with the greatest of
>all pleasures in science - surprise."
First, just the discovery of a possible "transitional form" does not
answer *how* it came about, which is what my quote was about. Here
is a sample of the problems involved:
"Let us notice what would be involved in the conversion of a land
quadruped into, first a seal-like creature and then into a whale.
The land animal would, while on land, have to cease using its hind
legs for locomotion and to keep them permanently stretched out
backwards on either side of the tail and to drag itself about by
using its fore-legs. During its excursions in the water, it must
have retained the hind legs in their rigid position and swim by
moving them and the tail from side to side As a result of this act
of self-denial we must assume that the hind legs eventually became
pinned to the tail by the growth membrane Thus the hind part of the
body would have become like that of a seal. Having reached this
stage, the creature in anticipation of a time when it will give
birth to its young under water, gradually develops apparatus by
means of which the milk is forced into the mouth of the young one,
and meanwhile a cap has to be formed round the nipple into which the
snout of the young one fits tightly, the epiglottis and laryngeal
cartilage become prolonged downwards so as tightly to embrace this
tube, in order that the adult will be able to breath while taking
water into the mouth and the young while taking in milk These
changes must be effected completely before the calf can be born
under water Be it noted that there is no stage intermediate between
being born and suckled under water and being born and suckled in the
air. At the same time various other anatomical changes have to take
place, the most important of which is the complete transformation of
the tail region. The hind part of the body must have begun to twist
on the fore part, and this twisting must have continued until the
sideways movement of the tail developed into an up-and-down
movement. While this twisting went on the hind limbs and pelvis
must have diminished in size, until the latter ceased to exist as
external limbs in all, and completely disappeared in most, whales.'
(Dewar D., "More Difficulties of the Evolution Theory", 1938,
pp23-4, in Denton M., "Evolution: A Theory in Crisis", 1985,
pp217-218).
Please note that all the above had to be substantially completed by
Neo-Darwinian micro-evolution, *in only 15 million years*, which
is the gap between Mesonychid, the putative land mammal
last common ancestor of the entire ordercetacea, dated at 55 mya,
and Prozeuglodon the first fully sea-adapted whale, dated at 40 mya:
"For decades researchers have claimed that whales are descended from
an extinct hyenalike land mammal, called a mesonychid, that walked
back into the sea between 50 and 60 million years ago. (Mesonychid
and all other land mammals are themselves descended from a fish that
crawled out of the sea much earlier.) By 40 million years ago the
transition from four-legged land animal to fishlike ocean dweller
was almost complete. The evidence is a fossil whale called
Prozeuglodon. It was perfectly adapted for life at sea-but as
University of Michigan paleontologist Philip Gingerich discovered in
1989, it still carried, near the end of its 15-foot body, a pair of
vestigial 6-inch legs." (Zimmer C., "Back to the Sea", Discover,
January 1995, pp83-84)
But second, I note that Gould sounds amazed that "a transitional
form" has finally turned up for the mammal-whale transition. This
only serves to underline the problem that there are simply not
enough "transitional forms" to support the Neo-Darwinist theory of
macro-evolution by small, incremental micro-evolutionary steps in an
ever-branching bush:
"Darwin's insistence that gradual evolution by natural selection
would require inconceivable numbers of transitional forms may have
been something of an exaggeration but it is hard to escape
concluding that in some cases he may not have been so far from the
mark. Take the case of the gap between modern whales and land
mammals. All known aquatic or semi-aquatic mammals such as seals,
sea cows (sirenians) or otters are specialized representatives of
distinct orders and none can possibly be ancestral to the
present-day whales. To bridge the gap we are forced therefore to
postulate a large number of entirely extinct hypothetical species
starting from a small, relatively unspecialized land mammal like a
shrew and leading successfully through an otter-like stage,
seal-like stage, sirenian-like stage and finally to a putative
organism which could serve as the ancestor of the modern whales.
Even from the hypothetical whale ancestor stage we need to postulate
many hypothetical primitive whales to bridge the not inconsiderable
gaps which separate the modern filter feeders (the baleen whales)
and the toothed whales. Moreover, it is impossible to accept that
such a hypothetical sequence of species which led directly from the
unspecialized terrestrial ancestral form gave rise to no collateral
branches. Such an assumption would be purely ad hoc, and would also
be tantamount to postulating an external unknown directive influence
in evolution which would be quite foreign to the spirit of Darwinian
theory and defeat its major purpose of attempting to provide a
natural explanation for evolution. Rather, we must suppose the
existence of innumerable collateral branches leading to many unknown
types. This was clearly Darwin's view and it implies that the total
number of species which must have existed between the
discontinuities must have been much greater than the number of
species on the shortest direct evolutionary pathway. In the diagram
opposite, which shows a hypothetical lineage leading from a land
mammal to a whale, while there are ten hypothetical species on the
direct path, there are an additional fifty-three hypothetical
species on collateral branches." (Denton M., "Evolution: A Theory
in Crisis", 1985, pp172,174)
The actual pervasive evidence of the *known* fossil record (and
Ambulocetus is no exception) is that `evolution' proceeded too
rapidly and directionally for a `blind watchmaker' to have been
driving it. Ambulocetus therefore better supports Mediate Creation
than Naturalistic Evolution.
>SJ>You can't fly with 2 percent of a wing or gain much protection
>from an iota's similarity with a potentially oncealing piece of
>cvegetation." (Gould S.J., "Bully for >Brontosaurus", 1991, p140)
PM>Of course the same comments applied to the eye, yet intermediate
>stages can have advantages other than fully functional flight or
>vision. Insolation
There is no evidence that feathers were originally developed for
"insulation". The palaeontologist Stahl writes:
"It is not difficult to imagine how feathers, once evolved assumed
additional functions, but how they arose initially presumably from
reptilian scales, defies analysis... The problem has been set
aside, not for want of interest, but for lack of evidence. No
fossil structure transitional between scale and feather is known,
and recent investigators are unwilling to found a theory on pure
speculation. Their supposition that feathers were derived from the
scales of reptiles is based upon the fact that both are nonliving,
keratinized structures generated from papillae on the surface of the
body. Since reptiles and birds are closely related, it seems more
likely that their papillae are homologous than that those of birds
arose de novo and replaced the reptilian scale-producing tissues.
The way a feather grows suggests that it is a scale much
modified...It seems, from the complex construction of feathers, that
their evolution from reptilian scales would have required an immense
period of time and involved a series of intermediate structures. So
far, the fossil record does not bear out that supposition. The
oldest bird known, Archaeopteryx, still exhibited skeletal
characters reminiscent of reptilian ones, but its feathers gave no
hint of primitive features. The imprint they left in the rock,
clear and sharp, makes it evident that the feathers of Archaeopteryx
were already in Jurassic time exactly like those of birds flying
today." (Stahl B.J., "Vertebrate history: Problems in Evolution",
Dover: New York, 1985, p350)
PM>or detection of light are some examples.
If there is "detection of light" then there is already an "eye" with
enormous complexity:
"Darwin convinced many of his readers that an evolutionary pathway
leads from the simplest light- sensitive spot to the sophisticated
camera-eye of man. But the question of how vision began remained
unanswered. Darwin persuaded much of the world that a modern eye
evolved gradually from a simpler structure, but he did not even try
to explain where his starting point-the relatively simple light-
sensitive spot-came from. On the contrary, Darwin dismissed the
question of the eye's ultimate origin: How a nerve comes to be
sensitive to light hardly concerns us more than how life itself
originated." He had an excellent reason for declining the question:
it was completely beyond nineteenth-century science. How the eye
works that is, what happens when a photon of light first hits the
retina-simply could not be answered at that time....
To Darwin, vision was a black box, but after the cumulative hard work
of many biochemists, we are now approaching answers to the question
of sight. The following five paragraphs give a biochemical sketch
of the eye's operation...
When light first strikes the retina a photon interacts with a
molecule called 11-cis-retinal, which rearranges within picoseconds
to trans-retinal. (A picosecond is about the time it takes light to
ravel the breadth of a single human hair.) The change in the shape
of the retinal molecule forces a change in the shape of the protein
rhodopsin, to which the retinal is tightly bound. The protein's
metamorphosis alters its behavior. Now called metarhodopsin II the
protein sticks to another protein, called transducin. Before bumping
into metarhodopsin II, transducin had tightly bound a small molecule
called GDP. But when transducin interacts with metarhodopsin II, the
GDP falls off, and a molecule called GTP binds to transducin. (GTP
is closely related to, but critically different from, GDP).
GTP-transducin-metarhodopsin II now binds to a protein called
phosphodiesterase, located in the inner membrane of the cell When
attached to metarhodopsin II and its entourage, the
phosphodiesterase acquires the chemical ability to "cut" a molecule
called cGMP (a chemical relative of both GDP and GTP). Initially
there are a lot of cGMP molecules in the cell, but the
phosphodiesterase lowers its concentration, just as a pulled plug
lowers the water level in a bathtub.
Another membrane protein that binds cGMP is called an ion channel.
It acts as a gateway that regulates the number of sodium ions in the
cell. Normally the ion channel allows sodium ions to flow into the
cell, while a separate protein actively pumps them out again. The dual
action of the ion channel and pump keeps the level of sodium ions in
the cell within a narrow range. When the amount of cGMP is reduced
because of cleavage by the phosphodiesterase, the ion channel closes,
causing the cellular concentration of positively charged sodium ions
to be reduced. This causes an imbalance of charge across the cell
membrane that, finally, causes a current to be transmitted down the
optic nerve to the brain. The result, when interpreted by the brain, is
vision.
If the reactions mentioned above were the only ones that operated in
the cell, the supply of 11-cis-retinal, cGME and sodium ions would
quickly be depleted. Something has to turn off the proteins that were
turned on and restore the cell to its original state. Several mechanisms
do this. First, in the dark the ion channel (in addition to sodium ions)
also lets calcium ions into the cell. The calcium is pumped back out
by a different protein so that a constant calcium concentration is
maintained. When cGMP levels fall, shutting down the ion channel,
calcium ion concentration decreases, too. The phosphodiesterase
enzyme, which destroys cGMF, slows down at lower calcium
concentration. Second, a protein called guanylate cyclase begins to
resynthesize cGMP when calcium levels start to fall. Third while all of
this is going on, metarhodopsin II is chemically modified by an
enzyme called rhodopsin kinase. The modified rhodopsin then. binds
to a protein known as arrestin, which prevents the rhodopsin from
activating more transducin. So the cell contains mechanisms to limit
the amplified signal started by a single photon.
Trans-retinal eventually falls off of rhodopsin and must be
reconverted to 1 l-cis-retinal and again bound by rhodopsin to get
back to the starting point for another visual cycle To accomplish this,
transretinal is first chemically modified by an enzyme to trans-retinol-
a form containing two more hydrogen atoms. A second enzyme then
converts the molecule to 1 l-cis-retinol. Finally, a third enzyme
removes the previously added hydrogen atoms to form 11-cis-retinal
a cycle is complete.
The above explanation is just a sketchy overview of the
biochemistry of vision. Ultimately, though, this is the level of
explanation for which biological science must aim. In order to
truly understand a function, one must understand in detail every
relevant step in the process. The relevant steps in biological
processes occur ultimately at the molecular level, so a
satisfactory explanation of a biological phenomenon-such as
sight, digestion, or immunity-must include its molecular
explanation.
Now that the black box of vision has been opened, it is no longer
enough for an evolutionary explanation of that power to consider
only the anatomical structures of whole eyes, as Darwin did in the
nineteenth century (and as popularizers of evolution continue to
do today). Each of the anatomical steps and structures that
Darwin thought were so simple actually involves staggeringly
complicated biochemical processes that cannot be papered over
with rhetoric. Darwin's metaphorical hops from butte to butte are
now revealed in many cases to be huge leaps between carefully
tailored machines-distances that would require a helicopter to
cross in one trip."
(Behe M.J., "Darwin's Black Box: The Biochemical Challenge to
Evolution", Free Press: New York, 1996, pp18-22)
[continued]
Regards.
Steve
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