For example, consider again the bicycle. 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.
A few weeks ago, I saw a person riding a bicycle down the road on the bicycle's back wheel (we used to call it a wheelie) because he thought he could get where he wanted to go faster. It wasn't just an up and then down motion. He rode that way for a sustained period of time. Maybe he wasn't using the bicycle exactly the way it was intended, but it was clearly functional. Exaptation. No matter. Onward.
Luskin tackles the differences between land-dwelling vertebrates and sea-going mammals:
Darwinists like Ken Miller view the dolphin's lack of factor XII as a case of convergent evolution, but we might also see it as evidence of a functional constraint or a case of common design. The fact that jawed fish lack factor XII is not necessarily evidence that their blood-clotting cascade was a "primitive evolutionary precursor" to the land-dwelling vertebrate blood-clotting cascade, but evidence of a functional constraint for water-dwelling vertebrates--a constraint which is confirmed in that dolphins also lack factor XII. This is an interesting issue that will require further research to sort out. In the mean time, any claims that Miller refuted Behe--or even Pandas--appear to be premature.
Would you like to take a look and place a bet on the results of that “further research,” Casey? As much as I’d like to win a few bucks from my friends at the Discovery Institute, it wouldn’t be sporting, since such research was actually done more than a decade ago [Semba et al, 1998]. Whales possess a Factor XII pseudogene, an inactivated version of the very same gene carried by land-dwelling mammals. That pseudogene is a direct mark of their common ancestry with other mammals, and disproves any suggestion that constraints on cetacean “design” required the absence of Factor XII. Rather, ordinary genetic processes knocked out the gene, and today the pseudogene remains merely as evidence of their evolutionary ancestry.
As Glenn Reynolds would say: "ouch."
Hat tip to Little Green Footballs.