"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, Origin of Species 
              
              With this statement, Charles Darwin provided a criterion by which 
              his theory of evolution could be falsified. The logic was simple: since evolution is a 
              gradual process in which slight modifications produce advantages for survival, it 
              cannot produce complex structures in a short amount of time. It's a step-by-step 
              process which may gradually build up and modify complex structures, but it cannot 
              produce them suddenly.
              
              Darwin, meet Michael Behe, biochemical researcher and professor at Lehigh University 
              in Pennsylvania. Michael Behe claims to have shown exactly what Darwin claimed would 
              destroy the theory of evolution, through a concept he calls "irreducible complexity." 
              In simple terms, this idea applies to any system of interacting parts in which the 
              removal of any one part destroys the function of the entire system. An irreducibly 
              complex system, then, requires each and every component to be in place before it will 
              function. 
              
              As a simple example of irreducible complexity, Behe presents the humble mousetrap. 
 
              
              
              
              
              It contains five interdependent parts which allow it to catch mice: the wooden 
              platform, the spring, the hammer (the bar which crushes the mouse against the wooden 
              base), the holding bar, and a catch. Each of these components is absolutely essential 
              for the function of the mousetrap. For instance, if you remove the catch, you cannot 
              set the trap and it will never catch mice, no matter how long they may dance over the 
              contraption. Remove the spring, and the hammer will flop uselessly back and 
              forth-certainly not much of a threat to the little rodents. Of course, removal of the 
              holding bar will ensure that the trap never catches anything because there will again 
              be no way to arm the system.
              
              Now, note what this implies: an irreducibly complex system cannot come about in a 
              gradual manner. One cannot begin with a wooden platform and catch a few mice, then add 
              a spring, catching a few more mice than before, etc. No, all the components must be in 
              place before it functions at all. A step-by-step approach to constructing such a 
              system will result in a useless system until all the components have been added. The 
              system requires all the components to be added at the same time, in the right 
              configuration, before it works at all. 
              
              How does irreducible complexity apply to biology? Behe notes that early this century, 
              before biologists really understood the cell, they had a very simplistic model of its 
              inner workings. Without the electron microscopes and other advanced techniques that 
              now allow scientists to peer into the inner workings of the cell, it was assumed that 
              the cell was a fairly simple blob of protoplasm. The living cell was a "black 
              box"-something that could be observed to perform various functions while its inner 
              workings were unknown and mysterious. Therefore, it was easy, and justifiable, to 
              assume that the cell was a simple collection of molecules. But not anymore. 
              Technological advances have provided detailed information about the inner workings of 
              the cell. Michael Denton, in his book Evolution: A Theory in Crisis, states "Although 
              the tiniest bacterial cells are incredibly small, weighing less than 10-12 grams, 
              each is in effect a veritable microminiaturized factory containing thousands of 
              exquisitely designed pieces of intricate molecular machinery, made up altogether of 
              one hundred thousand million atoms, far more complicated than any machine built by man 
              and absolutely without parallel in the non-living world." In a word, the cell is 
              complicated. Very complicated. 
              
              In fact, Michael Behe asserts that the complicated biological structures in a cell 
              exhibit the exact same irreducible complexity that we saw in the mousetrap example. In 
              other words, they are all-or-nothing: either everything is there and it works, or 
              something is missing and it doesn't work. As we saw before, such a system cannot be 
              constructed in a gradual manner - it simply won't work until all the components are 
              present, and Darwinism has no mechanism for adding all the components at once. 
              Remember, Darwin's mechanism is one of gradual mutations leading to improved fitness 
              and survival. A less-than-complete system of this nature simply will not function, and 
              it certainly won't help the organism to survive. Indeed, having a half-formed and 
              hence non-functional system would actually hinder survival and would be selected 
              against. But Behe is not the only scientist to recognize irreducible complexity in 
              nature. In 1986, Michael J. Katz, in his Templets and the explanation of complex 
              patterns (Cambridge: Cambridge University Press, 1986) writes: 
              
                "In the natural world, there are many pattern-assembly systems for 
                which there is no simple explanation. There are useful scientific explanations for 
                these complex systems, but the final patterns that they produce are so heterogeneous 
                that they cannot effectively be reduced to smaller or less intricate predecessor 
                components. As I will argue ... these patterns are, in a fundamental sense, 
                irreducibly complex..." 
              
              Katz continues that this sort of complexity is found in biology:
              
              
                "Cells and organisms are quite complex by all pattern criteria. 
                They are built of heterogeneous elements arranged in heterogeneous configurations, 
                and they do not self-assemble. One cannot stir together the parts of a cell or of an 
                organism and spontaneously assemble a neuron or a walrus: to create a cell or an 
                organisms one needs a preexisting cell or a preexisting organism, with its attendant 
                complex templets [templates]. A fundamental characteristic of the biological realm is that 
                organisms are complex patterns, and, for its creation, life requires extensive, and 
                essentially maximal, templets." 
              
              
              
              
              Behe presents several examples of irreducibly complex systems to prove his point, but 
              I'll just focus on one: the cilium. Cilia are hair-like structures, which are used by 
              animals and plants to move fluid over various surfaces (for example, cilia in your 
              respiratory tree sweep mucous towards the throat and thus promote elimination of 
              contaminants) and by single-celled organisms to move through water. Cilia are like 
              "oars" which contain their own mechanism for bending. That mechanism involves tiny 
              rod-like structures called microtubules that are arranged in a ring. Adjacent 
              microtubules are connected to each other by two types of "bridges"- a flexible linker 
              bridge and an arm that can "walk" up the neighboring microtubule. The cilia bends by 
              activating the "walker" arms, and the sliding motion that this tends to generate is 
              converted to a bending motion by the flexible linker bridges. 
              
              Thus, the cilium has several essential components: stiff microtubules, linker bridges, 
              and the "motors" in the form of walker arms. While my description is greatly 
              simplified (Behe notes that over 200 separate proteins have been identified in this 
              particular system), these 3 components form the basic system, and show what is 
              required for functionality. For without one of these components, the system simply 
              will not function. We can't evolve a cilium by starting with microtubules alone, 
              because the microtubules will be fixed and rigid - not much good for moving around. 
              Adding the flexible linker bridges to the system will not do any good either - there is 
              still no motor and the cilia still will not bend. If we have microtubules and the 
              walker arms (the motors) but no flexible linker arms, the microtubules will keep on 
              sliding past each other till they float away from each other and are lost. 
              
              This is only one of many biochemical systems that Behe discusses in his book, "Darwin's 
              Black Box". Other examples of irreducible complexity include the light-sensing system 
              in animal eyes, the transport system within the cell, the bacterial flagellum, and the 
              blood clotting system. All consist of a very complex system of interacting parts which 
              cannot be simplified while maintaining functionality. 
              
              Since the publication of "Darwin’s Black Box", Behe has refined the definition of 
              irreducible complexity. In 1996 he wrote that “any precursor to an irreducibly complex 
              system that is missing a part is by definition nonfunctional.” (Behe, M, 1996b. 
              Evidence for Intelligent Design from Biochemistry, a speech given at the Discovery 
              Institute's God & Culture Conference, August 10, 1996 Seattle, WA. 
              http://www.arn.org/docs/behe/mb_idfrombiochemistry.htm). 
              By defining irreducible complexity in terms of “nonfunctionality,” Behe casts light on 
              the fundamental problem with evolutionary theory: evolution cannot produce something 
              where there would be a non-functional intermediate. Natural selection only preserves 
              or “selects” those structures which are functional. If it is not functional, it cannot 
              be naturally selected. Thus, Behe’s latest definition of irreducible complexity is as 
              follows: 
              
                “An irreducibly complex evolutionary pathway is one that contains 
                one or more unselected steps (that is, one or more necessary-but-unselected 
                mutations). The degree of irreducible complexity is the number of unselected steps 
                in the pathway.” (A Response to Critics of Darwin’s Black Box, by Michael Behe, PCID, 
                Volume 1.1, January February March, 2002; http://iscid.org/) 
              
              Evolution simply cannot produce complex structures in a single 
              generation as would be required for the formation of irreducibly complex systems. To 
              imagine that a chance set of mutations would produce all 200 proteins required for 
              cilia function in a single generation stretches the imagination beyond the breaking 
              point. And yet, producing one or a few of these proteins at a time, in standard 
              Darwinian fashion, would convey no survival advantage because those few proteins would 
              have no function-indeed, they would constitute a waste of energy for the cell to even 
              produce. Darwin recognized this as a potent threat to his theory of evolution - the 
              issue that could completely disprove his idea. So the question must be raised: Has 
              Darwin's theory of evolution "absolutely broken down?" According to Michael Behe, the 
              answer is a resounding "Yes."
              
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