Evolution cannot account for irreducible complexity

Even though my opponent has not technically plagiarized, his entire argument against bacterial flagella – over 2200 characters – is just a series of quotes from two papers. I would ask that he please state his arguments in his own words, rather than pulling an entire argument from another paper and dropping it into the debate. I believe it is poor conduct. Per the rules, I will not directly rebut my opponent this round. <<< CON’S ARGUMENT >>> Michael Behe, intelligent design advocate, defines irreducible complexity (IC) as “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.”[1] Can evolution explain IC systems? Even Behe states that “demonstrating that a system is irreducibly complex is not proof that there is absolutely no gradual route to its production. Although an irreducibly complex system can’t be produced directly, one can’t definitively rule out the possibility of an indirect circuitous route.” [2] Fortunately, evolution works in indirect, circuitous routes that can lead to IC systems. It is not linear. It moves forward, back, and sideways. Evolution is known to alter biological systems by adding, removing, and modifying parts.[3][4][5] IC systems were explained by evolutionary scientists as early as 1918.[4] H. J. Muller correctly pointed out that to create an IC system, you simply need to (1) add a part, and (2) make that part necessary for the system to function. After this, removal of that part will destroy the function. This is called the “Muller Two-Step,” more on this later. The following section will show how these evolutionary principles of adding, removing, and modifying parts can lead to IC systems. Evolutionary theory EXPLAINS the development of IC systems 1. Evolution of IC systems can occur through scaffolding Scaffolding of parts is one evolutionary mechanism through which IC systems can be created. [6][7][8] For clarity, I will explain this process through analogy. Consider the example of a bridge.[See diagram] Imagine we have a precursor bridge of three parts. Two of these parts could be removed and the bridge would still function. This is NOT irreducibly complex because the function of the bridge can remain after removal of two of the parts. Now, let’s follow the Muller Two-Step for the evolutionary explanation of IC systems, we first (1) add a part and then (2) make that part necessary. STEP ONE: evolution adds a part, a top stone. This part, part D, is functionally redundant to part B. Functional redundancy is commonly observed in evolution.[9] Next, STEP TWO: evolution makes that part necessary by removing the middle stone. We now have an IC system because none of the remaining three stones can be removed without losing the bridge’s function. Thus, evolutionary principles explain how an IC system can develop through a non-linear manner by adding and removing parts. 2. Evolution of IC systems can occur through incremental addition The process of addition and modification of parts by evolution explains that IC systems can evolve when the interaction of components within a system goes from being merely “beneficial” to becoming “necessary”.[10][11] Consider the following diagram, we have part A that performs an enzymatic function. Part A interacts with Part B. Part B is helpful in enhancing Part A’s function but is not necessary – such as through structural stabilization of Part A. There are many examples of molecules whose function is enhanced in the presence of another molecule[12][13] Part A and B are not irreducibly complex at this point. Now, a mutation may occur in part A that causes it catalyze reactions faster – a good thing that improves survival – but that mutation might also cause it to destabilize in the absence of Part B, making B a necessary component of the system. Thus, in order for this system to perform its function, both parts are now required, and neither part can be removed without destroying function. It is therefore an IC system. Thus, evolution can explain the development of IC systems through the addition and modification of parts. An example of this process can be found here.[14] 3. Evolution of IC systems can occur through co-option Evolution of IC systems can also occur through a process known as co-option. Through this process, new functions arise from existing systems, and it is not necessary for a new system to evolve in total. Consider the following example of pentachlorophenol (PCP) metabolism by S. chlorophenolica.[15] PCP is a synthetic, highly toxic compound that was created by humans and used as a wood preservative since the 1930s. After exposure to this chemical for 80 years, one species of bacteria evolved a biochemical system that is capable of breaking down this toxic compound. This system is composed of three parts, each of which is completely necessary for the breakdown of PCP into a non-toxic product.[15] Scientists found that the bacteria, through mutation and natural selection, took a previous biochemical system, modified the parts by mutation and added one new part by gene duplication to create this IC system.[15] Thus, we have evidence of an IC system – that metabolizes a synthetic human-made compound – evolving in the last 80 years through the process of co-option. Commonly referenced IC Systems (and why they might not even be IC) Based on my previous sections, it should be clear to you now that evolution does explain the existence of IC systems. Thus, it does not matter whether the following systems are irreducibly complex or not, because evolution provides plausible explanations for their development. But I will point out their problems in any case. 1. Bacterial Flagellum The bacterial flagellum is commonly cited as an irreducibly complex system. This assertion was made before recent studies that show the flagellum is not irreducible. Parts of the flagellum can be removed and it will retain its function.[16][17] In 2010, two research groups independently removed two proteins – named Flil and FliH – from the bacterial flagella and found that it functioned even without these two proteins.[16][17] Thus, the bacterial flagellum is not irreducibly complex because its function does not cease when parts are removed. It demonstrably fails to meet the definition of IC. *Detailed evolutionary explanations for the flagellum exist, and I may describe them in the next round. 2. Vertebrate Clotting System The vertebrate clotting system is also claimed to be irreducibly complex. The jury is out on this issue, because no one has removed all the various components and determined function. There is reason to think it may not be IC, because it has been shown that at least two parts of the clotting system can be removed in mice and the system will still function.[18] Admittedly, the function is worse, wound-healing is worse, and the mice are more susceptible to certain ailments over their lifetime, but nonetheless it shows that the system can still perform its clotting functions without certain parts. *Detailed evolutionary explanations for the clotting system exist, and I may describe them in the next round. <<< CONCLUSION >>> I have shown that three different evolutionary pathways: (1) scaffolding; (2) incremental addition; and (3) co-option are processes that have been observed by scientists and that such processes CAN EXPLAIN the development of irreducibly complex systems. The notion of irreducible complexity fails because it demands that we work backwards from an existing system. Working backwards requires the incorrect assumption that evolution occurs by linear, gradual additions. We know, however, that evolution not only adds parts to systems, but can remove them, or cause them to change function. Thus, irreducibly complex systems can be explained by evolutionary theory. SOURCES In comments.