Re: summaries - explanation of the flagellum

There is an excellent explanation by Kenneth R. Miller of
Brown University found at:

http://www.millerandlevine.com/km/evol/design2/article.html


to explain the fallacy of the flagellum and irreducible complexity. I will attempt to summarize. Most of the words are not mine, but that of Kenneth R. Miller.

1. The flagellum has been presented so often as a counter-example to evolution that it might well be considered the "poster child" of the modern anti-evolution movement.

2. The flagellum reflects the supposed fact that it could not possibly have been produced by an evolutionary pathway.

3. The logical fallacy of the argument is "argument from personal incredulity". However, the fallacy is not accepted by anti-evolutionists.

4. ID claims to have found a reason why evolution could not have produced a structure like the bacterial flagellum, a reason based on sound, solid scientific evidence.

5. Irreducibly complex structures, we are told, could not have been produced by evolution, or, for that matter, by any natural process. They do exist, however, and therefore they must have been produced by something. That something could only be an outside intelligent agency operating beyond the laws of nature – an intelligent designer.

6. The irony is that researchers demolished its status as an example of irreducible complexity almost at the very moment it was first proclaimed.

7. An irreducibly complex structure is defined 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." (Behe 1996a, 39)

8. "An irreducibly complex system cannot be produced directly by numerous, successive, slight modifications of a precursor system, because any precursor to an irreducibly complex system that is missing a part is by definition nonfunctional. .... 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 1996b)

9. The phrase "numerous, successive, slight modifications" is not accidental. The very same words were used by Charles Darwin in The Origin of Species in describing the conditions that had to be met for his theory to be true. As Darwin wrote, if one could find an organ or structure that could not have been formed by "numerous, successive, slight modifications," his "theory would absolutely break down" (Darwin 1859, 191).

10. The argument of the gaps (or god of the gaps, if a deity is invoked) could be made since the Theory of Evolution has yet to explain the origins of ALL living things. However, this is a weak argument because Science is filling in the gaps as knowledge increases. Ironically, more gaps are created as the one big gap gets partially filled and creates two smaller gaps.

11. Example, in 1990 one could argue that it required intelligent design to explain how left-right asymmetry arises in vertebrate development. In 2002 the molecular mechanism was identified and thus no intelligent designer was required.

12. The argument of the irreducible complexity of the flagellum makes a sound scientific argument. It can be tested.

13. In the case of the flagellum, the assertion of irreducible complexity means that a minimum number of protein components, perhaps 30, are required to produce a working biological function. By the logic of irreducible complexity, these individual components should have no function until all 30 are put into place, at which point the function of motility appears.

14. If this one example is true, then the Theory of Evolution has a critical problem. Everyone agrees to this statement and it has NOT gone unnoticed to the scientific community.

15. There are numerous citations in the scientific literature pointing out the poor reasoning behind irreducible complexity. But these rebuttals are not enough.

16. The answer happened via steady progress of scientific work on the genes and proteins associated with the flagellum.

17, The flagellum – the supreme example of the power of this new "science of design" – has failed its most basic scientific test. The explanation is below.

18. ID claims "any precursor to an irreducibly complex system that is missing a part is by definition nonfunctional?"

19. It turns out that nature is filled with examples of "precursors" to the flagellum that are indeed "missing a part," and yet are fully-functional.

20. The type III secretory system (TTSS), allows gram negative bacteria to translocate proteins directly into the cytoplasm of a host cell (Heuck 1998). The proteins transferred through the TTSS include a variety of truly dangerous molecules, some of which are known as "virulence factors," and are directly responsible for the pathogenic activity of some of the most deadly bacteria in existence (Büttner and Bonas 2002; Heuck 1998).

21. The TTSS, a nasty little device that allows bacteria to inject these toxins through the cell membranes of its unsuspecting hosts, would seem to have little to do with the flagellum.

22. Molecular studies of proteins in the TTSS have revealed a surprising fact – the proteins of the TTSS are directly homologous to the proteins in the basal portion of the bacterial flagellum. These homologies extend to a cluster of closely-associated proteins found in both of these molecular "machines." On the basis of these homologies, McNab (McNab 1999) has argued that the flagellum itself should be regarded as a type III secretory system.

23. The TTSS does its dirty work using a handful of proteins from the base of the flagellum. From the evolutionary point of view, this relationship is hardly surprising. In fact, it's to be expected that the opportunism of evolutionary processes would mix and match proteins to produce new and novel functions. According to the doctrine of irreducible complexity, however, this should not be possible. If the flagellum is indeed irreducibly complex, then removing just one part, let alone 10 or 15, should render what remains "by definition nonfunctional." Yet the TTSS is indeed fully-functional, even though it is missing most of the parts of the flagellum.

24. The existence of the TTSS in a wide variety of bacteria demonstrates that a small portion of the "irreducibly complex" flagellum can indeed carry out an important biological function. Since such a function is clearly favored by natural selection, the contention that the flagellum must be fully-assembled before any of its component parts can be useful is obviously incorrect. What this means is that the argument for intelligent design of the flagellum has failed.


The article continues to demolish the counter arguments made by ID. The last paragraph is elegant:

As Darwin wrote, there is grandeur in an evolutionary view of life, a grandeur that is there for all to see, regardless of their philosophical views on the meaning and purpose of life. I do not believe, even for an instant, that Darwin's vision has weakened or diminished the sense of wonder and awe that one should feel in confronting the magnificence and diversity of the living world. Rather, to a person of faith it should enhance their sense of the Creator's majesty and wisdom (Miller 1999). Against such a backdrop, the struggles of the intelligent design movement are best understood as clamorous and disappointing double failures – rejected by Science because they do not fit the facts, and having failed religion because they think too little of God.