The
flagella of certain bacteria constitute a
molecular motor requiring the interaction of about 40 different protein parts. Behe asserts that the absence of any one of these proteins causes the flagella to fail to function, and that the flagellum "engine" is irreducibly complex as if we try to reduce its complexity by positing an earlier and simpler stage of its evolutionary development, we get an organism which functions improperly.
Scientists regard this argument as having been disproved in the light of research dating back to 1996 as well as more recent findings.[SUP]
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[68][/SUP] They point out that the basal body of the flagella has been found to be similar to the
Type III secretion system (TTSS), a needle-like structure that pathogenic germs such as
Salmonella and
Yersinia pestis use to inject
toxins into living
eucaryote cells. The needle's base has ten elements in common with the flagellum, but it is missing forty of the proteins that make a flagellum work.[SUP]
[69][/SUP] Thus, this system negates the claim that taking away any of the flagellum's parts would render it useless. On this basis,
Kenneth Miller notes that, "The parts of this supposedly irreducibly complex system actually have functions of their own."[SUP]
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[71][/SUP] Dembski's critique of this position is that phylogenetically, the TTSS makes an unlikely precursor to the flagellum given that TTSS is found in a narrow range of bacteria which makes it seem to be a late innovation, whereas flagella are widespread throughout many bacterial groups, which implies it was an early innovation.[SUP]
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[73][/SUP]
Experiments have shown that many proteins can be deleted from the flagellar apparatus without destroying its function,[SUP]
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[75][/SUP] even though its activity may be reduced in some of these cases.