Darwin's Black Box: The Biochemical Challenge to Evolution
A review of the book: Darwin's Black Box: The Biochemical Challenge to Evolution, By Michael J. Behe, Free Press, New York.
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"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".
(Charles Darwin, in The Origin of Species)
"To Darwin, the cell was a "black box" - its inner workings were utterly
mysterious to him. Now, the black box has been opened up and we know how
it works. Applying Darwin's test to the ultra-complex world of molecular
machinery and cellular systems that have been discovered over the past
40 years, we can say that Darwin's theory has "absolutely broken down"."
(Michael Behe, biochemist and author of Darwin's Black Box)
Darwin's Black Box is a bold attempt to re-establish the argument for design in living things. Ever since Darwin, the traditional idea that nature displays the handiwork of a divine Creator has been under attack. Many would say the outcome of the conflict has been decided: living things are not designed, they are designoid (having the appearance of design but produced by natural processes without intelligent direction and without an intended end-result). Although William Paley's "watch" argument had significant loopholes, Behe's contribution to this debate cannot be lightly dismissed.
The book's approach can be illustrated by reference to the eye, often used as an example of a complex organ. Darwin knew that if his theory was to survive, he must defend the idea of a gradually evolving structure, increasing in functional complexity. He could not propose a real pathway because, at that time, the eye was a "black box" and its workings were not understood. So, he proposed a gradualistic perspective based on an analogy: pointing to eyes of different complexity (from light-sensitive spots to `camera'-like structures). What has happened since then is that the biochemical processes behind vision have been elucidated and they are found to be "staggeringly complicated" (p.22). The problem for Darwin is that each of the anatomical structures he pointed to involve different biochemical systems. The structures are separated by huge gaps, even though there is an apparent continuum of morphological change. As a result, the analogy made by Darwin completely fails. (Incidentally, exactly the same criticism can be made of the more recent and much publicised computer simulation of the evolution of the eye as the whole approach is morphology-based).
Biological science developed in a rather fragmentary way in the early part of the 20th Century. It was brought together by neo-Darwinism, commonly known as the "evolutionary synthesis". The various disciplines within biology now have this synthesis as their integrating framework. Its advocates are often heard to express thoughts like: `without evolution, nothing in biology makes sense'. However, Behe points out that biochemistry was not part of the synthesis - as it did not exist as a separate discipline. Indeed, none of the inputs to the evolutionary synthesis were able to address biology at the molecular level. Biochemistry now exists - and the question must be asked "Does neo-Darwinism account for the molecular structure of life?" Behe responds: "It is the purpose of this book to show it does not" (p.25).
Because of the "Black Box" problem, there was a widespread tendency in the early part of the 20th Century to predict "simplicity" at the molecular level. Simple structures are, of course, much easier to explain! For example, insects were once thought to have no internal organs; bacteria and other single-celled life forms were considered "primitive" and simple; the cell was thought to be little more than a blob of jelly (Haekel said that the cell is a "homogeneous globule of protoplasm" (p.102)). But research has shown quite the contrary! The more the nuts and bolts of life are studied, the greater the complexity of their structure and function appears. But Behe is not just interested in complexity. He takes the discussion far beyond a sense of awe and wonder as the extraordinary mysteries of living things are revealed by the probings of science. Behe proposes that the building blocks of life exhibit the phenomenon of irreducible complexity. In his own words:
"By irreducibly complex I mean a single system composed of several well-matched, interacting parts that contribute to the basic function, wherein the removal of any one of the parts causes the system to effectively cease functioning. An irreducibly complex system cannot be produced directly (that is, by continuously improving the initial function, which continues to work by the same mechanism) by slight, successive modifications of a precursor system, because any precursor to an irreducibly complex system that is missing a part is by definition nonfunctional. An irreducibly complex biological system, if there is such a thing, would be a powerful challenge to Darwinian evolution. Since natural selection can only choose systems that are already working, then if a biological system cannot be produced gradually it would have to arise as an integrated unit, in one fell swoop, for natural selection to have anything to act on" (p.39).
Irreducibly complex systems come in two varieties: (a) several interacting parts, all of which are necessary for the basic function of the system to be achieved; and (b) separate elements of the system which act in sequence, all of which are necessary to accomplish the function of the system. Detailed studies are presented for the reader to appreciate specific examples of what irreducibly complex systems are like: cilia and the bacterial flagellum (chapter 3), the blood clotting cascade (chapter 4), protein transport within the cell (chapter 5), cellular defence mechanisms - the immune system cascade (chapter 6), and the cellular production of AMP (chapter 7). These chapters are meaty and demanding! For readers who need a short refresher course in biochemistry, one is provided as an appendix.
These systems are finely tuned. Impairing any part results in a loss of function which we observe macroscopically as damage, disease or even death. The so-called "gradual" incremental modifications required by neo-Darwinism appear, at the molecular level, to be major hindrances to the effectiveness of the systems. This is perceived by Behe as a substantial reason for questioning the relevance of neo- Darwinism when seeking to explain the origin of irreducibly complex systems.
The implication of this analysis is that no substantial explanations exist for the origin of irreducibly complex systems. Chapter 8 of the book sets out to document what has been said about the origin of the systems Behe has described. The emerging picture is an abysmal one for neo-Darwinistic theories of origins! Explanations never rise above the level of speculation, and the general pattern is for the whole issue of origins to be passed over without comment. Behe comments:
- "The very fact that none of these problems is even
addressed, let alone solved, is a very strong indication that Darwinism
is an inadequate framework for understanding the origin of complex biochemical
systems" (p.176).
Behe recognises that the argument is ultimately related to probability. The evidence is that the probability of finding Darwinian mechanisms (Behe includes discussion of non-Darwinian approaches and finds them wanting too) for the origin of these systems is so low that we can conclude that gradualistic mechanisms are totally inadequate. Darwinists will tend to cling to these low probabilities and not give up hope!
- "There is no magic point of irreducible complexity at which
Darwinism is logically impossible. But the hurdles for gradualism become
higher and higher as structures are more complex, more interdependent. Might
there be an as-yet-undiscovered natural process that would explain biochemical
complexity? No one would be foolish enough to categorically deny the possibility.
Nonetheless, we can say that if there is such a process, no one has a clue
how it would work. Further, it would go against all human experience, like
postulating that a natural process might explain computers. Concluding that
no such process exists is as scientifically sound as concluding that mental
telepathy is not possible, or that the Loch Ness monster doesn't exist"
(pp.203-204).
The inference of the book, therefore, is that the numerous examples of irreducible complexity discovered within the "black box" of the cell are witnesses to a Designer. Living things are not designoid: they are the products of intelligent and purposive design. This radical conclusion from a respected biochemist has sent ripples through the academic world and the media. "Darwin's Black Box" is a best-seller in the US. It is a very useful and thought-provoking book for all who take an interest in questions about origins.
David J. Tyler (April 1997)
