Stephen C. Meyer inadvertently falsified Behe's claims on the bacterial flagellum

[Nesslig20]

Just watched this video from the discovery institute by Stephen Meyer.

It's just 10 minutes long, but I can summaries it as such.

BACKGROUND: Michael Behe says that the bacterial flagellum (or rather all versions, there isn't just one) is irreducibly complex, i.e. it is an assembly of multiple interdependent components whereby the removal of one or more of these would cause the system to stop functioning. Any precursor to an irreducibly complex system that is missing a part is by definition nonfunctional, which means it couldn't have evolved from such precursor by successive slight modification. Critiques of Behe's argument have pointed out that the type-III secretory system (T3SS) is much like the bacterial flagellum, except for the fact that it is missing several key parts that are needed for it to rotate. Hence, T3SSs are not able to rotate like bacterial flagella, but they are still functional nonetheless. Hence, either bacterial flagella is not irreducible complex (there are plausible precursors to bacterial flagella with fewer parts that are still functional) or irreducible complex systems can evolve.

Here is a schematic image of a bacterial flagellum and the injectisome of the T3SS, and also a F-type ATP synthase for good measure.

The homologous (or equivalent) components are color coded.

Stephen Meyer's response in the video: T3SSs are probably younger than bacterial flagella, so the former is not a precursor to the latter. Hence, the T3SSs are either a "degenerative" version of bacterial flagella or both evolved independently from each other. [most of the video is spent on the argument from why the T3SS is likely older]. Both of these scenarios are consistent with Behe's claim that bacterial flagella could not have evolved from a simpler precursor.

And you know what...he might be right...about T3SSs originating more recently than flagella and that T3SSs likely evolved from flagella. The review paper from which the figure above comes from also says the same. However, Meyer is wrong when he says that this is still consistent with Behe's claim.

Let's backtrack and look what Behe's originally said in his book "Darwin's black box" page 39.

By irreducibly complex I mean 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. An irreducibly complex system cannot be produced directly (that is, by continuously improving the initial function, which continues to work by the same mechanism) by slight, successive modifications of a precursor system, because any precursor to an irreducibly complex system that is missing a part is by definition nonfunctional. An irreducibly complex biological system, if there is such a thing, would be a powerful challenge to Darwinian evolution. 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.

There are several problems with the phrases that Behe uses in this paragraph, that makes the definition very disjointed, which are pointed out in this paper. For example, it is unclear whether a system can be still regarded IC even if a simpler subsystem where several parts removed can still perform a functions - albeit a different ones. For example, a system performs functions XYZ but a simpler system that is missing one or several components cannot perform functions XYZ but does perform functions ABC. Would that still count as an IC system? Or if there is a simpler system is still able to serve (alternative) functions, does that mean that it is not IC by definition? There are several phrases like "contribute to the basic function" and "continues to work by the same mechanism" that suggest the former. But other phrases like "effectively cease functioning" and "by definition nonfunctional" that suggest that it's the latter. This ambiguity is an issue. If it is the former, then an IC system could still evolve, but indirectly from a simpler system with different functions. So by this definition, IC systems are not a problem for evolution. The only way an IC system could be a problem if it is defined as a system that cannot be reduced and still be functional in anyway whatsoever.

So, when Behe says that bacterial flagella is IC, he either means:

• 1st definition: that none of the essential components of flagella can be removed without loosing the function of flagella. As mentioned before, this does not mean it didn't evolve from a precursors that were still functional but with different functions.
• 2nd definition: that none of the essential components of flagella can be removed and still be functional in anyway (not even performing alternative functions). This would be a problem for evolution.

So why is Meyer wrong? What the T3SS shows is that several essential components of flagella can removed and the reduced system can still be functional. Whether or not the T3SS is in fact an actual precursor to flagella is irrelevant. The T3SS is still an equivalent to a reduced version of the flagellum (as Stephen Meyers says himself by calling it "degenerative" version of the flagellum that lost some of its components), which remains functional nonetheless. This also shows that a simpler and functional precursor to the flagella is not only plausible but possible. And that's not even mentioning the fact that F-type ATP synthases, as shown above, is a system with even less components and still functional (and there is pretty good evidence that ATP synthases are far older and direct precursors to the systems we have talked about as well as many others).

Ergo:

• By the 1st definition: the bacterial flagellum is an IC-system, but could still have evolved from functional precursors.
• By the 2nd definition: the bacterial flagellum is not an IC-system, since it could have evolved from functional precursors.

 

[Sparhafoc]

I've never actually seen his face before: he doesn't look at all how I expected.

But yeah, even in the first minute and a half, he's already acknowledged that his and Behe's past assertions were shown trivially wrong.