CB200.2: Blood clotting and Irreducibly Complexity

Claim CB200.2:

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Response:

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.
   
   
2. Blood clotting is not irreducibly complex. Some animals -- dolphins, for example -- get along fine without the Hagemann factor (Robinson et al. 1969), a component of the human blood clotting system which Behe includes in its "irreducible" complexity (Behe 1996, 84). 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 (Yong and Doolittle 2003).
   
   
3. Irreducible complexity is not an obstacle to evolution and doesn't imply design.

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