Thursday, November 16, 2006

Behe's Blood Clotting Cascade..... fairly represented.

In 'Darwin's Black Box' Michael Behe eludicated a handful of biochemical molecules and processes that would qualify as being irreducibly complex (IC). Meaning, that these processes or molecules exist in a manner that appears to defy a Darwinian explanation (an explanation that involves a gradual accruing of complexity guided by natural selection culling beneficial mutations).
One of Michael Behe's examples of an irreducibly complex process is the blood clotting cascade. This cascade bears a resemblance to a Rube Goldberg machine. The cascade involves numerous steps that must be met in succession before the final goal, formation of a blood clot, is achieved. Some of these proteins involved with the blood clotting cascade are: Hageman factor, HMK, prekallikrein, PTA, proconvertin, Christmas factor, antihemophilic factor, Stuart factor, proaccelerin, prothrombin, and fibrinogen.
Critics of Dr. Behe's proposal have pointed to one of the factors (Hageman factor) and then have pointed to an animal (dolphin) in which this factor does not reside. Usually what follows , after the clinging of champagne glasses dies down, is a comment or two about how short-sighted Dr. Behe was.
The only problem with the critique is that it is wrong. Michael Behe was quite clear in his book which factors constitute the IC components of the blood clotting cascade.... and Hageman factor was not only not mentioned, it was explicitly stated as being not part of the IC components.
How one overlooks 'Leaving aside the system before the fork in the pathway, where some details are less well known, the blood-clotting system fits the definition of irreducible complexity.' is not quite clear to me.
And, if there was any uncertainty with his intentions in this statement Dr. Behe further solidifies his claim with this 'The components of the system (beyond the fork in the pathway) are fibrinogen, prothrombin, Stuart factor, and proaccelerin.'
Why one would want to offer a critique of Michael Behe's work without having a moderately developed understanding of it eludes me.


Blogger William Bradford said...

Hi Doug. Earlier this year a PNAS article indicated that microRNA had a regulatory role in the development of platelets. It seems that Behe's IC position may be stronger than he thought when he authored his book. If the regulation of platelets is a prerequisite to their proper function then the putative evolution microRNA regulatory elements becomes part of the irreducible complexity paradigm.

9:10 AM  
Blogger CJYman said...

Hey, Doug, I've been meaning to tell you this for some time now. I love reading this one post here ... but I can only do so a limited number of times. I would think that, upon seeing how good this first post is, that you would have some more excellent thoughts on the subjet matter at hand (ID). So, I'm holding my breath ... waiting for some more posts.

P.S. thanks for the compliment on my blog!

3:46 PM  

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