Sunday, May 09, 2004

The Relentless Stupidity of Creationists Don't miss this magnificent post from Panda's Thumb contributor Andrea Bottaro. It discusses a recent posting at the IDEA center website. IDEA is an acronym for Intelligent-Design and Evolution Awareness. They organize student clubs at high schools and colleges across the country. To see the absurdity of this try to imagine a theory of relativity club.

One of the great frustrations of dealing with ID folks is that they don't make even the slightest bit of effort to get their basic facts right. All that matters is the illusion of scientific legitmamcy. For example, one of the biomolecular systems ID people have seized on as showing evidence of design is the human blood clotting cascade. It was a poor choice, since actually rather a lot is known about the evolution of blood clotting. Much of the pioneering work on this subject was done by Russell Doolittle. The IDEA folks devote some space to discrediting Doolittle's work, writing:

The essence of Doolittle’s response was to proclaim nothing more than homology between various proteins in the blood clotting cascade… This was the essence of Doolittle’s response to Behe: the blood clotting cascade proteins are similar (to varying degrees), therefore they must have evolved from one-another via duplication and co-optation. This mere sequence similarity, nothing less, and nothing more, formed the basis for Doolittle’s belief that the irreducibly complex blood clotting cascade could evolve. There was no discussion of intermediate stages showing how stepwise modifications in the current pathway could have been reversed back to a more simple stage. This is what graduate students were taught in a seminar directly intended to rebut the claims of Behe.

Accompanyig this assertion was a diagram showing the degree of protein similarity between the four proteins comprising hemoglobin and a fifth protein called myopin. This diagram bore the label

Above we see 5 proteins involved in the blood clotting cascade, arranged in a tree simply according to their percent sequence similarity.

Impressively scientific, no? There's just one problem. Hemoglobin and myobin have absolutely nothing to do with blood clotting. Here's Bottaro's reply:

I wasn’t at Doolittle’s seminar, but I have every reason to believe that the FAQ author wasn’t either, or if he/she was, he/she wasn’t paying much attention, because the figure shows a phylogenetic tree of hemoglobins, which are proteins involved in oxygen and CO2 transport, and have absolutely nothing to do with blood clotting. There are also 5 other errors (!) in the figure (2 obvious, 3 less so), but I’ll leave it to the readers to identify them (first one to get them all right wins a virtual pint at the PT virtual pub). (Emphasis in Original)

Now, Doolittle’s argument may have sounded unconvincing to an ID faithful, but two things are almost certain: he didn’t claim that hemoglobins are involved in blood clotting, and his argument did not rest simply on protein similarity. Several reviews of the evolution of the blood clotting cascade, including one by Doolittle himself, have appeared in the last couple of years - regardless of the original Doolittle seminar contents, certainly enough time for the FAQ author to get acquainted with the data [1]. In fact, the blood clotting cascade has been essentially ignored in recent ID literature, perhaps because of the accumulating evidence for evolutionary precursors and overall evolutionary plasticity of the clotting system in various vertebrates, as discussed in the references above. Recent evidence has linked the appearance of some duplicated gene pairs (those for clotting factors IX and X, V and VIII, respectively) to a global genome duplication that is thought to have occurred right before the emergence of jawed vertebrates (sharks, bony fish, and land vertebrates). If this is correct, jawless vertebrates (or agnathans, like lampreys and hagfish) would be expected to display simplified cascades containing a reduced set of these components. Indeed, although jawless fish gene data are still partial, of the major clotting components only thrombin, fibrinogen, and 3 members of the FVII/FIX/FX/protein C family have been identified so far. The origin of the FV/FVIII duplicated pair is also thought to likely date to the same whole genome duplication, and the search for their agnathan precursor is ongoing. As the jawless fish gene catalog becomes more complete, it will be interesting to see whether these predictions will be borne out.

Bottaro has many more observations of a similar bent. He also has all the necessary links to the original post.

Facts mean nothing to creationists.


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