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Blood clotting is irreducibly complex (Talk.Origins)
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(Talk.Origins quotes in blue)
1. The blood clotting systems appears to be put together by using whatever long polymeric bridges are handy. There are many examples of complicated systems made from components that have useful but completely different roles in different components. There is also evidence that the genes for blood clotting (indeed, the whole genome) duplicated twice in the course of its evolution (Davidson et al. 2003). The duplication of parts and co-opting of parts with different functions gets around the "challenge" of irreducible complexity evolving gradually.
This is based on comparative studies that assume Evolution in their conclusions, no place do they demonstrate that such processes can actually occur. While the duplication and co-opting of parts would indeed help, it does not solve the challenge of irreducible complexity evolving gradually. The organism still needs have all the right parts together in the same place and correctly assembled. That problem is not addressed by Talk Origins.
2. Blood clotting is not irreducibly complex. Some animals -- dolphins, for example -- get along fine without the Hagemann factor, a component of the human blood clotting system which Behe includes in its "irreducible" complexity. Doolittle and Feng (1987) predicted that "lower" vertebrates would lack the "contact pathway" of blood clotting. Work on the genomes of the puffer fish and zebrafish have confirmed this
- This would seem to simply show that dolphins and other animals which lack the Hagemann factor have a blood clotting chemistry that is different from humans. That’s not a surprise from a creation perspective, particularly given the fact that dolphins live in water while humans live on land.
- The most this shows is that Behe erred on this one point.
- The fact that some animals do not need the Hagemann factor for blood clotting says nothing about humans. If humans can get along without it, then Talk Origins would have a point, but otherwise the Hagemann factor could still be part of the irreducible complexity of human blood.
Behe's Response to this Objection
In fact, this objection to Behe’s argument for the irreducible complexity of the blood-clotting cascade is entirely beside the point. In the Kitzmiller v. Dover case, Behe, in his testimony, dealt explicitly with this ‘rebuttal’ as expressed by Dr. Ken Miller. Here is the relevant portion of Behe’s testimony, running from page 25, line 9 to page 30, line 5 (A = Behe):
Thus, this objection doesn’t even deal with Behe’s case for the IC of the blood-clotting cascade; it completely and utterly misses the target. As he points out in his testimony, Behe expressly limited his argument in Darwin’s Black Box to a specific sector of this biochemical pathway. This ostensible rebuttal to Behe addresses an entirely different sector; one that Behe explicitly excluded from his case for the IC of the cascade.
If Darwinists wish to rebut Behe, they must address the case that he actually makes rather than a mischaracterization of it. As it is, Behe’s attribution of IC to the blood-clotting cascade stands – unscathed by this misdirected and irrelevant attack.
3. Irreducible complexity is not an obstacle to evolution and doesn't imply design.
This statement is bogus, being based on flawed logic.
This includes the impossible demand that those who hold to the position that irreducible complexity implies design disprove all possible evolutionary scenarios, even those that have not been invented yet.
- Discovery Institute’s ‘Dover Intelligent Design Trial Information’ page
- Behe’s Dover Testimony – Day 1, Morning
- Behe’s Dover Testimony – Day 1, Afternoon
- Behe’s Dover Testimony – Day 2, Morning
- Behe’s Dover Testimony – Day 2, Afternoon