In his day, Darwin’s ideas were revolutionary and could not be falsified with the vast amounts of scientific data that are so easily available today. Darwin admitted that there remained great gaps in his theory of transitional species when he said,
“But just in proportion as this process of extermination [natural selection] has acted on an enormous scale, so must the number of intermediate varieties, which have formerly existed, be truly enormous. Why then is not every geological formation and every stratum full of such intermediate links? Geology assuredly does not reveal any such finely graduated organic chain; and this, perhaps, is the most obvious and serious objection which can be urged against the theory. The explanation lies, as I believe, in the extreme imperfection of the geological record” (Darwin, 1998: 406).
However, he believed that these gaps would be compensated for after enough scientific data had been gathered. Sadly enough, that hope has failed and Humanity is left with even more perplexing questions regarding human evolution. Michael Behe, Ph.D. and Professor of Biochemistry at Lehigh University, has embarked on an in-depth study of the biochemical processes that regulate the human body. He has summarized some of his work in his book entitled, Darwin’s Black Box. The term “black box;” has effectively been used to illustrate his point of the many assumptions Darwin made without examining the fine details. A “black box” is used to represent a process where the box receives input and produces output, but the contents and workings inside the box are unknown. This symbolic representation is often used in engineering when only the input and output are needed. However, when dealing with the science of evolutionary processes, the complete understanding down to the smallest molecule is required to sufficiently support the notion that life has evolved through eons of time to the present complexity demonstrated in the human body. In the 1800′s, Darwin and his associates were unable to investigate these details of bodily functions, but since the invention of the electron microscope, these details have been unmasked. For brevity, two examples of the human molecular operations at the cellular level will be examined which clearly run the theories of neo-Darwinian evolution aground. They are the minimum requirements for the functionality of the human cilium and the clotting of the human blood.
Behe first introduces his argument regarding irreducibly complex systems and minimal function with the following definition.
“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 functionality. An irreducibly complex system cannot be produced directly… 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” (Behe, 1996:39).
Behe continues with the distinction between necessary and sufficient conditions required for a functioning system. An irreducibly complex system is necessary to perform a given function, but it is not sufficient. The materials, parts, components, etc. that make up the irreducibly complex system may be available in different qualities, sizes, properties, but only a precise combination of these components may merit a sufficient condition for system functionality.
“In order to be a candidate for natural selection a system must have minimal function: the ability to accomplish a task in physically realistic circumstances… but even complex machines that do what they are supposed to do may not be of much use… Nonetheless, minimal function is critical in the evolution of biological structures… Irreducibly complex systems are nasty roadblocks for Darwinian evolution; the need for minimal function greatly exacerbates the dilemma” (Behe, 1996:45-46).
To summarize, a system is functional if it meets the necessary condition that it contains all the irreducibly complex components and it meets the sufficient condition that it performs the minimal function. After examining the following biochemical examples, Darwin’s suggestion that “[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” (Darwin, 1998:232) becomes reality.
The human cilium “is a structure that, crudely put, looks like a hair and beats like whip” (Behe, 1996:59). The cilium is used to transport liquid over the surface of a stationary cell, or when free to move acts as an oar to propel the cell forward. This cellular operation has a very complicated and detailed structure. As space does not permit a thorough biochemical explanation in this article, the reader is encouraged to research this structure separately. Behe sums up the problem in the following.
“Ciliary motion certainly requires microtubules; otherwise, there would be no strands to slide. Additionally it requires a motor, or else the microtubules of the cilium would lie stiff and motionless. Furthermore, it requires linkers to tug on the neighboring strands, converting the sliding motion into a bending motion, and preventing the structure from falling apart. All of these parts are required to perform one function: ciliary motion… The complexity of the cilium… is inherent in the task itself… The question is, how did the cilium arise?” (Behe, 1996:65-65).
This structure and system as described by Behe is an irreducibly complex system with minimal function. After performing a thorough investigation as to the possible evolutionary steps which resulted in the formation of this system, Behe concludes that no one knows how this system came to be through evolutionary steps. If only one part of this system is missing, the system is functionless and there is no advantage or disadvantage in the remaining parts. Thus, nature has nothing to select to bring about this ciliary system. There has been an enormous increase in the knowledge of how the cilium works, but many people have falsely assumed that if they don’t know how it evolved, surely someone else does. This, in fact, is not the case. The evolution of the cilium is a mystery to science. No one can suggest even a possible route of development, much less demonstrate scientifically plausible processes. This swimming machine is but one of the many biochemical machines for which evolution offers no explanation as to origins. If Darwin had been aware of these drastic objections to his theory, he surely would have questioned the validity of it. The cilium is not an organ, per say, in the human body—as organ development was the perspective Darwin had—but is a very small and complicated machine available in many cells that make up the organs.
The clotting mechanism in the human blood stream is a breathtaking operation to study and difficult to fully grasp. There are so many intertwined chemicals and reactions that constitute a fully functioning blood clotting mechanism. The reader is again encouraged to research the blood clotting process in the human body separately for a thorough comprehension of its complexity. Behe states that,
“…when a person suffers a cut it ordinarily bleeds for only a short time before a clot stops the flow; the clot eventually hardens, and the cut heals over… Biochemical investigation, however, has shown that the blood clotting is a very complex, intricately woven system consisting of a score of interdependent protein parts. The absence of, or significant defects in, any one of a number of the components causes the system to fail: blood does not clot at a proper time or at the proper place” (Behe, 1996:78).
If the blood does not clot in the correct place, a person may suffer severe problems in blood supply to other parts of the body; if the clot does not occur at the correct time, a person may continue to hemorrhage and death may result. Either of these failures has a detrimental effect on the human body and if the blood clotting mechanism were anything but fully functional, there would be no means in which nature could select its gradual progression to its present state. Blood clotting is an irreducibly complex system. If any of the components involved (i.e. fibrinogen, prothrombin, Stuart factor, proaccelerin and their many chemical forms) is missing, the system ceases to function. Gradual progression through incremental steps is impossible as far as neo-Darwinian theory is concerned. “There are other ways to stop blood flow from wounds, but those ways are not step-by-step precursors to the clotting cascade. For example, the body can constrict blood vessels near a cut to help stanch blood flow” (Behe, 1996:86). On blood clotting, Behe concludes with the fittingly remarks.
“The discussion is meant simply to illustrate the enormous difficulty (indeed, the apparent impossibility) of a problem that has resisted the determined efforts of a top-notch scientist [Russell Doolittle, Harvard Ph.D., professor of biochemistry at the Center for Molecular Genetics, University of California] for four decades. Blood coagulation is a paradigm of the staggering complexity that underlies even apparently simple bodily processes. Faced with such complexity beneath even simple phenomena, Darwinian theory falls silent” (Behe, 1996:97).
These two examples of biochemical challenges to the neo-Darwinian theory of evolution are a mere fragment of the total volume of biochemical irreducibly complex machines, which possess highly specialized components to perform the minimal functions required by the organism. There is absolutely no concrete evidence for gradual progression of these irreducibly complex systems—from the base elements to the current specialized forms—and no scientist has been able to explain, on scientific terms, the means by which natural selection, as described by Darwin, could have acted on the initial system to perfect it to its present finely-tuned state.
Behe, Michael J. Darwin’s Black Box. New York, NY: Touchstone Rochefeller Center, 1996.
Darwin, Charles. The Origin of Species. Modern Library ed. Toronto, Ontario: Random House of Canada Limited, 1998.