Professor James Curtsinger, in his Oct. 11 column, “Intelligent Design 101: Short on science, long on snake oil,” takes Lehigh University biochemist Michael Behe to task for his concept of irreducible complexity. Behe’s concept, which argues that the information-rich cellular structures cannot be explained by unguided evolution from less information-rich components, is “irrelevant to evolution” according to Curtsinger.

To support this claim, Curtsinger makes two points. First, he criticizes Behe because he and other intelligent design theorists haven’t “produced important scientific insights in the past nine years.” Second, he says that Behe’s chief example of irreducible complexity – a submicroscopic outboard motor called the bacterial flagellum – is actually reducible to a smaller, functional system called the type III secretory system, or TTSS, a molecular lethal injector carried by the black plague bacteria (Yersinia pestis) and other pathogens such as the bacteria called Shigella.

A few more details on the TTSS injector will lead us to different conclusions.

At the third biannual Bacterial Locomotion and Signal Transduction (BLAST) meeting in January 1995, University of Idaho microbiologist and intelligent design theorist Scott Minnich presented a radical idea. “Is the TTSS lethal injector apparatus an example of inverse evolution – the transformation of one information-rich system to another not-quite-as-information-rich system?”

Minnich’s idea was picked up by several of the conference attendees. For example, Rasika Harshey and Adam Toguchi wrote in their 1996 Trends in Microbiology review, “some nonmotile pathogens [without flagella], such as Shigella and Yersinia pestis (S. Minnich, personal communication), appear to contain flagellar genes. Could these be a vestige of formerly motile species? Is it likely that pathogens have exploited the flagellar secretory mechanism to transfer proteins directly into a target host cell?” This radical idea, fleshed out by Minnich’s publications over the past decade, has ended up being correct.

So, how does this example affect both of Curtsinger’s arguments?

First, it shows that the intelligent design theorists haven’t been sitting around twiddling their flagella for the past nine years. Rather, they’ve been busy using their perspective to propose scientific hypotheses that have turned out to be true.

Second, it indicates that the TTSS lethal injection apparatus, although smaller than the more complicated flagellar outboard motor system, was not a precursor to the flagellum. If anything, the flagellum may have degenerated or devolved into the TTSS. No one thinks virulence would have come before motility. So the TTSS has nothing to do with explaining where the flagellum came from. It does show that composite machines exist, but modularity is a hallmark of design. As University of California-San Diego biologist Milton Saier puts it in his 2004 Trends in Microbiology review, though “evolution tends toward complexity Ö the Fla [flagellar] system came first.” Therefore, to invoke the TTSS when attempting to account for the origin of flagella, one must presuppose the existence of the very thing that needs explaining.

Let’s be perfectly clear. Intelligent design theorists are not saying that one structure can’t change into another, and they’re not saying that, once a flagellum existed, it couldn’t have become something simpler, like the TTSS, through unguided evolution. They are saying is the existence of the flagellum, in all of its information-rich glory, is something that must be adequately explained. More importantly, they are saying any explanation that does not take into account the origin of the information is not adequate, and unguided evolution falls in this category.

Curtsinger may not have known the full story behind the relationship between the TTSS and flagellum. Still, a look at what national reporters are saying about intelligent design’s influence on universities such as Harvard and Berkeley would have helped him see that it is anything but “irrelevant.” Just last Sunday, for instance, Boston Globe journalist Peter Dizikes wrote that “the looming presence of Intelligent Design has started having a discernible impact on evolutionary scientists” and quoted Harvard systems biologist Marc Kirschner as saying “we shouldn’t dismiss (intelligent design theorists’) questions, even if some are ill-intentioned.”

The bottom line is that intelligent design is relevant to evolution and is a catalyst for new directions, such as the new book that Kirshchner has co-written with Berkeley biologist John Gerhhart, titled “The Plausibility of Life.” Intelligent design is making a difference in evolution precisely because some scientists have paid attention to the questions it asks.

Chris Macosko is a professor of chemical engineering and materials science. Please send comments to [email protected].