Ah, the things you learn from creationists…
If you’ve ever read about intelligent design (a k a “the progeny of creationism”), you’ve probably encountered their favorite buzz words, “irreducible complexity.” If you take a piece out of a complex biological system (like the cascade of blood-clotting proteins) and it fails to work, this is taken as evidence that the system could not have evolved. After all, without all the pieces in place, it couldn’t work.
Scientists have shown over and over again that this is a false argument. At the famous intelligent-design trial in Dover in 2005, Pennsylvania, for example, Brown biologist Ken Miller showed how dolphins and other species are missing various proteins found in our blood-clotting cascade, and they can still clot blood. (Here’s Miller on Youtube giving a lecture on the experience–the blood starts to clot at 39:00.)
Three years later, the creationists are still trying to salvage irreducible complexity. This generally involves a bait-and-switch game. Today, for example, the Discovery Institute tells us that the evidence of dolphins does not touch the argument for irreducible complexity. See, what you have here are two different irreducibly complex systems, with one that just happens to have an extra part. Just think about bicycles…
“Bicycles have two wheels. Unicycles, having only one wheel, are missing an obvious component found on bicycles. Does this imply that you can remove one wheel from a bicycle and it will still function? Of course not. Try removing a wheel from a bike and you’ll quickly see that it requires two wheels to function. The fact that a unicycle lacks certain components of a bicycle does not mean that the bicycle is therefore not irreducibly complex.”
Of course not. No. It’s not as if five seconds of googling could turn up a bicycle that still functioned without both wheels…
Hey! You there! Get off that bike! You’re ruining a metaphor!
Update, 12/31: Lonely housewife in Duluth says: “To be fair, in the picture the guy has one foot on the ground”
I, for one, believe that both feet are off the ground, judging from the angle of the rider’s body, arms, and drooping cigarette. But scholars of irreducibly complex velocipedality will no doubt debate this point fiercely for centuries. Lest we lose sight of the fundamental revelation here, let me point you to Abercrombie Fitch’s discovery on YouTube. (What’s with these commenter handles these days, you may wonder? Don’t ask me.) Behold:
Originally published December 30, 2008. Copyright 2008 Carl Zimmer.