Are ID advocates guilty of selective hyperskepticism?
Professor Larry Moran evidently thinks we are. In a recent post, he writes:
Let’s take the formation of bacterial flagella as a good illustration of how they use selective hyperskepticism. They begin with the unshakeable assumption that gods exist, that that they must have created life. They then find an example of something complex where the exact evolutionary pathway hasn’t been worked out and declare that the gods made it. They refuse to answer any questions about how, when, where, and why and they refuse to present any evidence that gods did it.
When evolutionary biologists present some evidence that bacterial flagella could have arisen by evolution the creationists turn into selective hyperskepticists by demanding a detailed blow-by-blow account of the historical process complete with reams of scientific evidence. Of course, they would never think of applying these same criteria to their own worldview.
A few quick points in response:
1. Although many Intelligent Design advocates (including myself) believe in God, Intelligent Design does not specify the identity of the Designer (or designers). From a purely scientific standpoint, there is currently no way to answer this question.
2. Intelligent Design does not “begin with the unshakeable assumption that gods exist,” as Professor Moran alleges. We don’t even begin with the assumption that a Designer exists; rather, it is something we attempt to argue for, on the basis of probabilities. Professor Moran should know us better than that.
3. Intelligent Design advocates do not demand a “detailed blow-by-blow account of the historical process” by which bacterial flagella originated. All we ask for is a semi-plausible calculation showing that the probability of bacterial flagella originating in our cosmos by known natural processes probably exceeds 10^(-150). Heck, I’d be happy with a calculation showing that for just one of the proteins in the bacterial flagellum. I can understand why Professor Moran might balk at calculating the odds of life originating by natural processes, but one protein? We’re talking about a single molecule here. Why be so coy, Professor?
4. If Professor Moran wants to see some good arguments for the claim that bacteria flagella could not have arisen by evolutionary processes, I would invite him to read Jonathan McLatchie’s 2012 monograph, The Bacterial Flagellum: A Motorized Nanomachine. Allow me to quote a few key excerpts:
The most common response to the claim that the bacterial flagellum manifests irreducible complexity has been to point to the type III secretion system (T3SS), a needle-like syringe used by certain bacteria (e.g. the archetype for this system Yersinia pestis) to inject toxins into organisms, as a possible evolutionary predecessor. There are a number of problems, however, with this hypothesis. For one thing, it sidesteps the need to also explain the components of the type III export machinery (including FlhA, FlhB, FliR, FliQ, FliP, FliI etc.), at least most of which are essential for its function. Indeed, one study “examined the effect of loss-of-function mutations in each of the type III secretion-associated genes encoded within SPI-1 on the assembly of the needle complex,” finding that all six of the Type III secretion system components homologous to those listed above are required for the system’s function (Sukhan et al., 2001)…
Even in the event that it was somehow feasible to evolve the flagellar export apparatus and basal body by evolution, there is the problem of producing the filament. Leaving aside the fact that the flagellar filament is assembled with the assistance of an essential capping protein encoded by FliD, the exported flagellin monomers need to stick both to each other and to the export machinery’s outer components (so that they are not lost from the cell into the surrounding medium). The specific and co-ordinated mutations required to facilitate such an innovation are likely to be well beyond the reach of a Darwinian process.
The motor itself exhibits irreducible complexity, and is dependent on the critical proteins FliG, MotA, MotB and FliM. Remove any one of those proteins and the motor will completely cease to function. Inducing mutations in FliG, for example, yields “a non-motile, or Mot-, phenotype, in which flagella are assembled but do not rotate,” (Lloyd and Blair, 1997). A study that conducted a “deletion analysis of the FliM flagellar switch protein of Salmonella typhimurium” found that “deletions at the N-terminus produced a counterclockwise switch bias, deletions in the central region of the protein produced poorly motile or nonflagellate cells, and deletions near the C-terminus produced only nonflagellate cells,” (Toker et al.,1996).
Many more examples could be given. But the bottom line is this: The bacterial flagellum
exhibits remarkable design, and irreducible complexity at every tie. When so much of the assembly process and functional operation of the flagellum appears to resist explanation in evolutionary terms, perhaps it is time to lay aside such a paradigm and begin the search for alternatives.
There’s more. Jonathan McLatchie has also written a follow-up article titled, Two of the World’s Leading Experts on Bacterial Flagellar Assembly Take on Michael Behe (Evolution News and Views, March 8, 2013), in which he responds to claims by Kelly Hughes and David Blair of the University of Utah, two of the world’s leading experts on bacterial flagellar assembly, that the bacterial flagellum is not irreducibly complex. Hughes and Blair make these claims in their recent book, Microbes and Evolution: The World that Darwin Never Saw. Here are some of the highlights from McLatchie’s response:
…[Hughes and Blair] proceed to show that sub-components within the flagellar structure are homologous to other bacterial organelles. For example, they correctly point out that the stator proteins MotA and MotB are homologs of ExbB and ExbD, which form part of the TonB-dependent active transport system and which serve to energize transport of vitamin B12, and iron-chelating compounds called siderophores, across the outer membrane of Gram-negative bacteria. ExbB/D and MotA/B are also known to be homologous to TolQ/R, which play an important role in the maintenance of outer membrane stability.
…Is a demonstration of molecular homology of flagellar components to proteins found in other cellular organelles really an adequate defeater to the argument from irreducible complexity? I’m not convinced. Homology does nothing to demonstrate that the necessary transitions are evolutionarily feasible (Gauger and Axe, 2011), and it has been shown that the process of gene duplication and recruitment, as a source of evolutionary novelty, is extremely limited (Axe, 2010).
The central challenge posed by irreducible complexity is that functional utility is separated by discontinuous leaps in complexity, which cannot be scaled by a blind search. It is the need for multiple, coordinated changes that delivers a substantive challenge to neo-Darwinian evolutionary theory. This challenge stands regardless of whether sub-components within the flagellar apparatus can serve functions in other organelles…
Moreover, there are a number of flagellar components that are presently not known to have homologs in non-flagellar systems. Examples include the rod cap FlgJ, the L and P ring proteins FlgH and FlgI, the MS ring-rod junction protein FliE, the filament capping protein FliD, and the anti-sigma factor FlgM. A number of these components form part of irreducibly complex subsystems of the flagellum.…
Hughes and Blair further argue that flagellar protein export can be accomplished by only a subset of the ten proteins once thought to be indispensable (FliF, FliG, FliM, FliN, FliO, FliP, FliQ, FliR, FlhA, and FlhB). According to Hughes and Blair, the export apparatus’s “functional core” is comprised of just FliP, FliQ, FliR and FlhA. I would be interested in seeing the literature that Hughes and Blair are drawing on at this point (no citation is offered). My own reading would certainly indicate that all of the above proteins are indispensable for flagellar protein export, with the exception of FliO (which is missing in some systems — see Barker et al., 2010). In the case of FliF, flagellar assembly requires “a short stretch of amino acids at the immediate C terminus” (Grünenfelder et al., 2003). Mutant studies on FliG, FliM and FliN (which are present in 26, 34 and over 100 copies respectively in E. coli and Salmonella) demonstrate that they are also essential for flagellar assembly (Brown et al., 2007, Paul et al., 2006, Tang and Blair, 1995).
To conclude, the claim of Hughes and Blair to have refuted Behe on the bacterial flagellum is unfounded. Although there are sub-components of the flagellum that are indeed dispensable for assembly and motility, there are numerous subsystems within the flagellum that require multiple coordinated mutations. The flagellar motor is not the kind of structure that one can at all readily envision being produced in Darwinian step-wise fashion.
I might mention that some of these proteins are pretty big, with a length of over 250 amino acids (see here.
Professor Moran might also want to have a look at Jonathan McLatchie’s recent post, The Flagellar Filament Cap: “One of the Most Dynamic Movements in Protein Structures”.
I have yet to see a response to any of these papers by Jonathan McLatchie from Professor Moran. I’m still waiting.
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UNRELATED POSTSCRIPT:
In a recent post, Professor Moran queried my claims about endemic violence in the secular paradise of Denmark, on the basis that he never saw any during a one-week stay there. He should open his eyes a little. If he did, he would discover that (secular) violence against women is rampant there (and also in other Nordic countries), as is domestic violence against immigrant women, religiously motivated gang violence (see also here and here) and rampant gangsterism – not to mention a high and rising rate of burglaries, for reasons that remain elusive. Some paradise!