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Probe Ministries
Darwin's Black Box
Dr. Ray Bohlin
Darwin's Black Box: The Biochemistry of the Cell
What do mouse traps, molecular biology, blood clotting, Rube
Goldberg machines, and irreducible complexity have to do with each
other? At first glance they seem to have little if anything to do
with each other. However, they are all part of a recent book by
Free Press titled, Darwin's Black Box: The Biochemical
Challenge to Evolution by Michael Behe. Michael Behe is a
biophysics professor at Lehigh University in Pennsylvania and his
book, released last summer, has been causing a firestorm of
activity in academic circles ever since.
The stranglehold that Darwinism has had in the biological sciences
for decades has already been weakened over the last 30 years due to
the new creationist movement and more recently by the push from
intelligent design theorists. But Behe's new book may end up being
the straw that broke the camel's back. Usually books like these are
released by Christian publishers or at least a secular press that
is small and willing to take a chance. Also, creationist books are
rarely sold in secular bookstores or reviewed in secular
publications. Darwin's Black Box has gained the attention
of evolutionists not normally accustomed to responding to anti-
evolutionary ideas in the academic arena. People like Niles
Eldredge from the American Museum of Natural History, Daniel
Dennett, author of Darwin's Dangerous Idea, Richard
Dawkins of Oxford University and author of The Blind
Watchmaker, Jerry Robison of Harvard University, and David
Hull from the University of Chicago have all been forced to respond
to Behe either in print or in person.
In summary, the reason for all this attention is that they readily
admit that Behe is clearly a reputable scientist from a reputable
institution and his argument is therefore more sophisticated than
they are accustomed to hearing from creationists. Mild, backhanded
compliments aside, they unreservedly say he is flat wrong, but they
have gone to much greater lengths in the literature, from the
podium, and in the electronic media to explain precisely why they
think he is wrong. Creationists and intelligent design theorists
are usually dismissed out of hand, but not Behe's Darwin's
Black Box.
Behe's simple claim is that when Darwin wrote The Origin of
Species, the cell was a mysterious black box. We could see the
outside of it, but we had no idea of how it worked. In
Origin, Darwin stated,
If it could be demonstrated that any complex organ
existed, which could not possibly have been formed by numerous,
successive, slight modifications, my theory would absolutely break
down. But I can find no such case.
Simply put, Behe has found such a case. Behe claims that with the
opening of the black box of the cell through the last 40 years of
research in molecular and cell biology, there are now numerous
examples of complex molecular machines that absolutely break down
the theory of natural selection as an all-encompassing explanation
of living systems. The power and logic of his examples prompted
Christianity Today to name Darwin's Black Box as
their 1996 Book of the Year. Quite a distinction for a book on
science published by a secular publisher!
In this essay I will be examining a few of Behe's examples and
detailing further just how the scientific community has been
reacting to this highly readable and influential book.
Irreducible Complexity and Mousetraps
Behe claims the data of biochemistry argues strongly that many of
the molecular machines in the cell could not have arisen through a
step-by-step process of natural selection. In contrast, Behe claims
that much of the molecular machinery in the cell is irreducibly
complex.
Let me first address this concept of irreducible complexity. It's
really a quite simple concept to grasp. Something is irreducibly
complex if it's composed of several parts and each part is
absolutely necessary for the structure to function. The implication
is that such irreducibly complex structures or machines cannot be
built by natural selection because in natural selection, each
component must be useful to the organism as the molecular machine
is built. Behe uses the example of a mousetrap. A mousetrap has
five parts that are absolutely necessary for the mousetrap to
function. Take any one of these parts away and the mousetrap can no
longer catch mice.
The mousetrap must contain a solid base to attach the four other
parts to, a hammer that clamps down on the mouse, a spring which
gives the hammer the necessary power, a holding bar which holds the
now energized hammer in position, and a catch to which the holding
bar is secured, holding the hammer in coiled tension. Eventually,
the jiggling action of a mouse, lured to the catch by a tasty
morsel of peanut butter, causes the holding bar to slip away from
the catch, releasing the hammer to spring down upon the
unsuspecting mouse.
It's fairly easy to imagine the complete breakdown of functionality
if you take away any of these five parts. Without the base, the
other parts can't maintain the proper stability and distance from
each other to be functional; without the spring or hammer, there is
no way to actually catch the mouse; and without both the catch and
holding bar, there is no way to set the trap. All the parts must be
present and accounted for in order for a mouse to be caught and the
machine to function at all.
You can't build a mousetrap by Darwinian natural selection. Let's
say you have a factory that produces all five parts of a mousetrap
but uses them for different purposes. Over the years as the
production lines change, leftover parts of no-longer-made
contraptions are put aside on shelves in a storage room. One
summer, the factory is overrun with mice. If someone were to put
his mind to it, he might run by the storage room and begin to play
around with these leftover parts and just might construct a
mousetrap. But those pieces, left to themselves, are never going to
spontaneously self-assemble into a mousetrap. A hammer-like part
may accidentally fall from its box into a box of springs, but it's
useless until all five parts are assembled so they can function
together. Nature would select against the continued production of
the miscellaneous parts if they are not producing an immediate
benefit to the organism.
Michael Behe simply claims that we have learned that several of the
molecular machines in the cell are just as irreducibly complex as
a mousetrap and, therefore, just as unable to be constructed by
natural selection.
The Mighty Cilium
One of Behe's examples is the cilium. Cilia are tiny hair-like
structures on the outside of cells that either help move fluid over
a stationary cell, such as the cells in your lungs, or serve as a
means of propelling a cell through water, as in the single-celled
paramecium. There are often many cilia on the surface of a cell,
and you can watch them beat in unison the way a stadium crowd
performs the wave at a ball game.
A cilium operates like paddles in a row boat; however, since it is
a hair-like structure, it can bend. There are two parts to the
operation of a cilium, the power stroke and the recovery stroke.
The power stroke starts with the cilium essentially parallel to the
surface of the cell. With the cilium held rigid, it lifts up,
anchored at its base in the cell membrane, and pushes liquid
backwards until it has moved nearly 180 degrees from its previous
position. For the recovery stroke, the cilium bends near the base,
and the bend moves down the length of the cilium as it hugs the
surface of the cell until it reaches its previous stretched out
position, again having moved 180 degrees back to its original
position. How does this microscopic hair-like structure do this?
Studies have shown that three primary proteins are necessary,
though over 200 others are utilized.
If you made a cross-section of a cilium and made a photograph of it
with an electron microscope, you would see that the internal
structure of the cilium is composed of a central pair of fibers
surrounded by an additional 9 pairs of these same fibers arranged
in a circle. These fibers or microtubules are long hollow sticks
made by stacking the protein tubulin. The bending action of cilia
depends on the vertical shifts made by these microtubules.
The bending is caused by another protein that is stretched between
the pairs of tubules called nexin. Nexin acts as a sort of rubber
band connector between the tubules. As the microtubules shift
vertically, the rubber band is stretched taut, the microtubules
continue to shift if they bend. Whew! I know this is getting
complicated, but hang with me a little longer. The microtubules
slide past each other by the action of a motor protein called
dynein. The dynein protein also connects two microtubules together.
One end of the dynein remains stationary on one microtubule, while
the other end releases its hold on the neighboring microtubule and
reattaches a little higher and pulls the other microtubule down.
Without the motor protein, the microtubules don't slide and the
cilium simply stands rigid. Without nexin, the tubules will slide
against each other until they completely move past each other and
the cilium disintegrates. Without the tubulin, there are no
microtubules and no motion. The cilium is irreducibly complex. Like
the mousetrap, it has all the properties of design and none of the
properties of natural selection.
Rube Goldberg Blood Clotting
Rube Goldberg was a cartoonist in the earlier part of this century.
He became famous for drawing weird contraptions that must go
through many seemingly unnecessary steps in order to accomplish a
rather simple purpose. Over the years, some evolutionists have
alluded to living systems as Rube Goldberg machines as evidence of
their construction by natural selection as opposed to being
designed by a Creator. Things such as the Panda's thumb and the
intricate workings of the many varieties of orchids are said to be
contrived structures that an intelligent creator surely would have
found a better way of doing.
If you have never seen a cartoon of a Rube Goldberg machine, let me
describe one for you from Mike Behe's book, Darwin's Black
Box. This one is titled the "Mosquito Bite Scratcher." Water
falling off a roof migrates into a drain pipe and collects into a
flask. In the flask is a cork that floats up as the glass fills.
Inserted in the cork is a needle that eventually rises high enough
to puncture a suspended paper cup filled with beer. The beer then
sprinkles onto a nearby bird that becomes intoxicated and falls off
its platform and onto a spring. The spring propels the inebriated
bird onto another platform where the bird pulls a string (no doubt
mistaking it for a worm in its intoxicated state). The pulled
string fires a cannon underneath a small dog, frightening him and
causing him to flip over on his back. His rapid breathing raises
and lowers a disk above his stomach which is attached to a needle
positioned next to a mosquito bite on a man's neck allowing the
bite to be scratched, causing no embarrassment to the man while he
talks to a lady.
Well, this machine is obviously more complicated than it needs to
be. But the machine is still designed and as Behe claims, it is
also irreducibly complex. In other words, if one of the steps fails
or is absent, the machine doesn't work. The whole contraption is
useless. Well, there are a few molecular mechanisms in our bodies
that are very similar to Rube Goldberg machines and therefore
irreducibly complex. One is the blood-clotting cascade. When you
cut your finger an amazing thing happens. Initially, it begins to
bleed, but if you just leave it alone, after a few minutes, the
flow of blood stops. A clot has formed, providing a protein mesh
that initially catches the blood cells and eventually closes up the
wound entirely, preventing the plasma from escaping as well.
This seemingly straightforward process involves over a dozen
different proteins with names like thrombin, fibrinogen, Christmas,
Stuart, and accelerin. Some of these proteins are involved in
forming the clot. Others are responsible for regulating clot
formation. Regulating proteins are needed because you only want
clots forming at the site of a wound not in the middle of flowing
arteries. Yet other proteins have the job of removing the clot once
it is no longer needed. The body also needs to eliminate the clot
when it has outlived its usefulness, but not before.
Now it's easy to see why some, when considering the blood-clotting
cascade, wonder if a Creator could have devised something simpler.
But that assumes we fully understand the system. Perhaps it
absolutely needs to be this way. Besides, this doesn't in any way
diminish the fact that even a Rube Goldberg machine is designed
just as the blood clotting system seems to be.
Silence of Molecular Evolution and the Reaction
Clearly, the irreducible complexity inherent in many biochemical
systems not only precludes the possibility that they evolved by
Darwinian natural selection, but actually suggests the strong
conclusion that some kind of intelligent design is necessary. Behe
makes a very significant point by recognizing that the data that
implies intelligent design doesn't necessarily mean one knows who
the designer is. Inferring that intelligent design is present is a
reasonable scientific conclusion. Planetary astronomers, for
example, claim that we will be able distinguish a radio signal from
space that was sent by an intelligent civilization from the
surrounding radio noise even though we won't initially understand
it and won't know who sent it.
Yet the astounding complexity of the cell has gone largely
unnoticed and greatly unreported to the general public. There is an
embarrassed silence. Behe speculates as to why; he says,
Why does the scientific community not greedily embrace
its startling discovery? Why is the observation of design handled
with intellectual gloves? The dilemma is that while one side of the
elephant is labeled intelligent design, the other side might be
labeled God (p.233).
This may also help to account for another curious omission that
Behe highlights, the almost total lack of scientific literature
attempting to describe how complex molecular systems could have
arisen by Darwinian natural selection. The Journal of Molecular
Evolution was established in 1971, dedicated to explaining how
life at the molecular level came to be. One would hope to find
studies exploring the origin of complex biochemical systems in this
journal. But, in fact, none of the papers published in JME
over the entire course of its life as a journal has ever proposed
the origin of a single complex biochemical system in a gradual
step-by-step Darwinian process.
Furthermore, Behe adds,
The search can be extended, but the results are the
same. There has never been a meeting, or a book or a paper on
details of the evolution of complex biochemical systems (p. 179).
Behe's sophisticated argument has garnered the attention of many
within the scientific community. His book has been reviewed in the
pages of Nature, Boston Review, Wall Street
Journal, and on many sites on the Internet. While some have
genuinely engaged the ideas and offered serious rebuttal, most have
sat back on Darwinian authority and claimed that Behe is just lazy
or hasn't given the evolutionary establishment enough time. Jerry
Coyne in Nature (19 September 1996, pp. 227-28) put it this
way:
There is no doubt that the pathways described by Behe
are dauntingly complex, and their evolution will be hard to
unravel. Unlike anatomical structures, the evolution of which can
be traced with fossils, biochemical evolution must be reconstructed
from highly evolved living organisms, and we may forever be unable
to envisage the first proto-pathways. It is not valid, however, to
assume that, because one man cannot imagine such pathways, they
could not have existed.
But that's precisely the point; it is not one man but the entire
biochemical community that has failed to elucidate a specific
pathway leading to a complex biochemical system.
I highly recommend Behe's book. Its impact will be felt for many
years to come.
© 1997 Probe Ministries International
About the Author
Raymond G. Bohlin is executive director of Probe Ministries.
He is a graduate of the University of Illinois (B.S., zoology),
North Texas State University (M.S., population genetics), and the
University of Texas at Dallas (M.S., Ph.D., molecular biology). He
is the co-author of the book The Natural Limits to Biological
Change and has published numerous journal articles. Dr. Bohlin
was named a 1997-98 Research Fellow of the Discovery
Institute's Center for the Renewal of Science and Culture. He can
be reached via e-mail at rbohlin@probe.org.
What is Probe?
Probe Ministries is a non-profit corporation whose mission is to reclaim the
primacy of Christian thought and values in Western culture through media,
education, and literature. In seeking to accomplish this mission, Probe provides
perspective on the integration of the academic disciplines and historic
Christianity.
In addition, Probe acts as a clearing house, communicating the results of
its research to the church and society at large.
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Updated: 22 September 1998
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