Science Literature

The iconic status of the bacterial flagellum for ID is easily justified, even though there are numerous other structures with complexities that are similarly astounding. In view of its potential for applications in nano-machines, the flagellum has been much studied and research shows no signs of abating.

The bacterial flagellum (source here)

Interest is not just in the mechanisms of providing torque and the way this is transmitted to the propeller. The researchers are intensely interested in the assembly of the flagellum. A recent review article declares that the assembly of this structure "poses the formidable problem of coupling temporal gene expression to specific stages of the organelle-assembly process".

"To function properly, each component of the final molecular machine that assembles by protein polymerisation must achieve an accurate size and subunit composition. Coordination of this assembly process is aided by gene regulatory mechanisms that manage the logistics of component production, whereas other mechanisms regulate the timing of the specific subunits that are being exported.
[. . .]
"Many regulatory checkpoint mechanisms of flagellum assembly have been elucidated, and these present a sophisticated strategy for coordinating gene expression to the assembly process."

As a review, this article presents a helpful overview of thinking about the assembly process. ID advocates also affirm assembly via natural processes - the intelligent agency is located in the design of the structure and the orchestration of the assembly process. However, the concluding paragraph of this paper introduces new ideas that are not discussed earlier:

"Finally, it seems that the bacterial flagellum is a structure of great complexity. In an attempt to understand why, it is not necessary to resort to intelligent designers, because surely a designer would have fashioned a simpler structure and gene regulation system. We only need to be reminded that evolution demands that changes occur on the existing structure - no starting from scratch. It is fair to say that we are at long last making a dent in our understanding of how this evolutionary process might have occurred for the reducibly complex bacterial flagellum and the beautiful result it has produced."

What is the argument here? It seems to be that the bacterial flagellum and its gene regulation system is too complex to have been fashioned by an intelligent designer! "Surely", affirm the authors, a designer would have gone for something simpler. Perhaps we should congratulate them for devising a novel argument against ID. Normally, we are caricatured as saying 'things are too complicated to have arisen by natural processes', but this argument suggests that the flagellum is too complicated even to have been the result of intelligent agency!

We could be more sympathetic to this reasoning if the authors could identify that part of the spectrum of complexity where the ID argument is justified. However, what we have here is a 'no-win' situation for ID. Furthermore, the reasoning is based on false premises. ID advocates base their design inferences on the recognition of complex specified information, not on "complexity" per se. The issue is not whether the structure is "of great complexity" but whether it exhibits complex specified information. Researchers need to assess whether the phenomenon under investigation could have arisen by the tinkering process of evolutionary transformation or whether it bears the marks of an exquisitely engineered artefact. Since the authors refer to the bacterial flagellum as "a beautiful result", it is not unreasonable to rule out incremental botching. (For more on this, go here). This suggests the burden of proof here rests on those who defend tinkering rather than intelligent agency.

My final comment here is to ask the question why this paragraph is deemed relevant to the subject matter of the review. It does not emerge from the data or the analysis. The word "surely" is lacking in content, appealing to gut feeling rather than evidence. Like so many academic contributions about structures exhibiting complex specified information, the evolutionary anchor is spin rather than substance. If reasoning like this is deemed acceptable in an academic paper, there should be no question of the legitimacy within science forums of arguing the case for intelligent agency.

Coordinating assembly of a bacterial macromolecular machine
Chevance, F.F.V., and Hughes, K.T.
Nature Reviews Microbiology, 6, 455-465, (June 2008)

The assembly of large and complex organelles, such as the bacterial flagellum, poses the formidable problem of coupling temporal gene expression to specific stages of the organelle-assembly process. The discovery that levels of the bacterial flagellar regulatory protein FlgM are controlled by its secretion from the cell in response to the completion of an intermediate flagellar structure (the hook-basal body) was only the first of several discoveries of unique mechanisms that coordinate flagellar gene expression with assembly. In this Review, we discuss this mechanism, together with others that also coordinate gene regulation and flagellar assembly in Gram-negative bacteria.

See also:

Coppedge, D.F. Cellular Machines Work Like Cameras, Winches and Turboprops, (Creation-Evolution Headlines, 3 September 2008)