Friday, May 04, 2007

The Flagellum and the Mousetrap

One of the many problems Darwinists have in trying to explain away the many holes and illogical lapses there are in macroevolutionary theory (especially since the electron microscope was developed) are the existence of what Dr. Michael Behe calls, “irreducibly complex mechanisms” that are at work in the human body. By this Dr. Behe means tiny, living machines that have several parts working together toward a common goal – none of which parts have any purpose except as a critical and necessary component of the machine.

None of the attempts to explain the step by step development of the eye, for example, has been successful once it was discovered that the starting point always used, the light-sensitive spot, was itself an incredibly intricate system. Another irreducibly complex mechanism is the flagellum, a tiny motor that helps propel cells and other organisms within a living animal. There was an interesting comment this week on this matter on the website,

DARWINISM GONE WILD: Neither sequence similarity nor common descent address a claim of Intelligent Design

Metal mousetrap parts

Okay, so one day a guy walks up to you and says irreducible complexity is no problem for a random, Darwinian-like evolutionary process. In fact, he can explain how a mousetrap could be made step by step. That’s great, you reply, tell me. Easy, says he. He has just finished a detailed analysis of the standard mechanical mousetrap and discovered that, except for the wooden base, all the parts are made of metal! What’s more, he’s even looked at non-standard mechanical traps, and their pieces are all made of metal, too! Also, after much sleuthing he’s noticed that the mousetrap spring has a lot in common with the spring inside his ballpoint pen — both are made of metal, and both are curled into spirals.

Fascinating, you reply, please go on. Go on? What, are you blind? Don’t you see? asks he. The mousetrap spring must have arisen from something like the pen’s spring, to make the beginning of the mousetrap. Then the spring duplicated to form the other metal parts, which were added one by one to make the trap we see today. What more could a reasonable person ask for?

You point out that it isn’t quite obvious to you how that helps, that the function of the mousetrap would seem to be missing from all those parts, and that while all the parts were being added, the system still wouldn’t work like a trap. In fact, you note that the scenario says nothing at all about how the mouse-trapping function arose.

IDiot!, he mutters.

Common descent versus random mutation/natural selection

That’s pretty much the scenario being played out after the recent online publication of a paper by Liu and Ochman (1) in the Proceedings of the National Academy of Sciences. The gist of the paper is that the workers compared the sequences of the dozens of proteins of the flagellum of the gut bacterium E. coli to each other, to other E. coli proteins, and to the flagellar proteins of other kinds of bacteria. They noted plausible sequence similarities among the flagellar proteins to each other, but not so much to other bacterial proteins. So Liu and Ochman concluded that all 24 proteins of the flagellum core must have descended from a single gene for a single protein!

As I’ll mention below, other people find that claim very dubious, but let’s leave that aside for now. Let’s concentrate on the fact that this is being touted as an answer to claims of intelligent design. As I’ve pointed out many times, beginning with Darwin’s Black Box over a decade ago, the argument for intelligent design in biology has little to do with protein-sequence similarity or common ancestry, for the same reason that knowing all the parts are made of metal doesn’t explain the mousetrap. Even if all those parts are made of metal, and even if they derived serially from each other or from some primordial piece of metal, that doesn’t even begin to explain how a mousetrap could be built step by step by a random process. In the same way, even if all the proteins of the flagellum derived serially one from the other, or from some magical precursor protein, that doesn’t even try to explain how a flagellum could be built step by step by a Darwinian process.

Let me emphasize the point: Common descent is one thing. Random mutation and natural selection is something completely different. Evidence for common descent is NOT evidence for RM/NS. At the very best, protein sequence comparisons may say something about common descent, but they aren’t support for Darwin’s crucial claim that the startlingly elegant, functional complexity of life arose by random mutation culled by natural selection. The PNAS paper is quite irrelevant to that. The bottom line is that, despite the authors’ apparent confusion, the paper does not even try to address the irreducible complexity of the flagellum or its need for intelligent design.


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