Yet more evidence of science (and scientists) at work. I've made two posts about the PNAS paper by Renyi Liu and Howard Ochman claiming that “core components of the bacterial flagellum originated through the successive duplication and modification of a few, or perhaps even a single, precursor gene.”
In the first post, I pointed out that Nick Matzke argued there are some serious flaws in the paper and concluded that “This dispute illustrates the process of successive refinement through which scientific knowledge accumulates.” A couple of months later I noted that a correction to the original article made me uneasy about Liu and Ochman's conclusion. I also noted that “the uncertainty about these results doesn't disturb me. Uncertainty is the bread and butter of scientific research.”
Well, science continues to work, and it works by challenging one interpretation with new data, additional hypotheses, and new interpretation. Over on Panda's Thumb, Matzke summarizes a review of flagellum evolution by W. Ford Doolittle and Olga Zhaxybayeva. They don't settle the issue, but yet again they illustrate how science works.
Liu, Ochman, Matzke, Doolittle, Zhaxybayeva, and other continue to propose and test scenarios for flagellum evolution. They haven't settled on the answer yet, but they're clearly making progress. I'd say that's pretty good evidence that it's not irreducibly complex.