Literature

Earlier this year, Liu and Ochman made some dramatic claims about how the bacterial flagellum evolved: by the simple processes of successive duplications and diversifications. They discounted lateral gene transfer (LGT) as having had any significant influence. This received much applause, one critical blog and it was briefly reviewed here.
In a recent contribution to Current Biology, we read: "there are some caveats we evolutionists should consider before hailing Liu and Ochman as our next champions in the war against unreason." The caveats are to be welcomed. It was surprising to read the uncritical acclaim accompanying the publication of the original paper and a more measured assessment of its bold claims is to be welcomed. However, the reference to "war against unreason" is misguided. The authors are referring to ID, yet ID scientists are strong defenders of reason. Their reason leads them to make design inferences, and design inferences are totally unacceptable to scientists who have adopted the philosophy of naturalism.
After mentioning with approval the blog by Matzke, the authors write: "Equally problematic, we think, is their conclusion that "proteins forming the flagellum, the rod, hook and filament proteins, originated in an order that mirrors the 'inside-out' flagellar assembly process". Common sense might suggest such a scenario, but only rooted trees, which Liu and Ochman do not provide, can prove it."
Regarding the LGT claim, the authors (one of whom is a champion of LGT) write: "Critics of LGT often assume that trees with little resolution, because they do not show statistically significant conflict, must be in agreement and support vertical descent. But most often there is simply insufficient signal. Making vertical descent the null hypothesis is to assume that which was to be proved - and in this case to give false credibility to the claim for a common evolutionary history." This argument is very interesting, because it is closely related to arguments that have often been made by ID scientists. The problem of "little resolution" is widespread and the result is that researchers end up confirming their own assumptions.
It is obviously important that scientific debate be encouraged. There are serious problems linked to researchers apparently proving their presuppositions. We ask: when will this critical thinking be applied to science itself? Many scientists assume naturalism and then go on to 'prove' that naturalism can explain everything. This approach to science is one of the things ID scientists are seeking to change.

Evolution: Reducible Complexity - The Case for Bacterial Flagella
W. Ford Doolittle and Olga Zhaxybayeva
Current Biology, 17(13), 3 July 2007, R510-R512 | doi:10.1016/j.cub.2007.05.003

Abstract: A recent paper, which will surely figure centrally in the debate between evolutionists and Intelligent Design creationists, proposes a (perhaps too simple) scheme for the evolution of bacterial flagella.

See also:
Sequence similarities in the bacterial flagellum: what do they mean? ARN Literature Blog, 04/19/07