Chapter 20
Flagella and Cilia
ID promoters love to talk about the little hairy extensions that many cells have, which are called cilia and flagella. Cells that have nucleuses have both long threadlike extensions, called flagella, and shorter ones called cilia. These cilia and flagella have the same internal structure, but cilia are much shorter.
Bacteria are a very different kind of organism from us. They are one-celled organisms, and the cells are much smaller and do not have nucleuses. Bacteria also have threadlike extensions called flagella, but these have a completely different structure from the flagella found in cells that have nucleuses.
The first thing that ID folks do wrong is they don’t distinguish a cilium from a flagellum, and the second is that they don’t know the difference between bacteria and everything else.
Thing One: Bacteria Don’t Have Cilia
So the first thing you need to do when talking to ID promoters on this subject is to ask them whether they are talking about the flagella found on bacteria, or the flagella found on cells with nucleuses, such as the human sperm cell. These kinds of cells are completely different, and so are their flagella.
Humans and bacteria are not closely related, and their flagella are entirely mechanically different. Saying that they are the same would be like saying that the human arm and a jellyfish tentacle are the same. So always ask—which flagellum is ID talking about?
Sometimes ID promoters talk about the cilia on bacteria. For the record, cilia don’t exist on bacteria. So if you ever hear an ID promoter talking about the bacterial cilium, you know he’s off base before he even gets started on anything else. Cilia only show up on cells that have nucleuses, which bacteria don’t. Cilia are shorter versions of flagella, but with the same structure. Sometimes, cilia will cover large portions of their cell’s surface. But they never show up on bacteria at all.
The Cilium —“Irreducible Complexity Squared”?
So, in his book The Edge of Evolution: The Search for the Limits of Darwinism, ID promoter Michael Behe tells us that cilia and flagella in cells with nucleuses can’t be made without a particular cellular system called IFT, which stands for intraflagellar transport. He says that IFT is universally required for cilium and flagellum construction.
He also claims that both the cilium (or flagellum) itself and the IFT are irreducibly complex. Since both the cilium and IFT are (according to him) irreducibly complex, this would make a completed cilium even more irreducibly complex, since even the system that makes it can’t be reduced, and if that system is removed, then the cilium can’t be constructed. He christens this setup “irreducible complexity squared”!50 He thinks this is a great argument.
There’s just one problem. Cilia and flagella can be made without IFT. So he simply got the science wrong.
It gets worse. In the same book, Dr. Behe also states that the parasite that gives us malaria is a great example of intelligent design. He acts as though he has studied malaria with great love and care. However, the malarial parasite, which has a nucleus and is not a bacterium, does build a flagellum, but it doesn’t have IFT!
So the very organism that Dr. Behe claims to have studied with such great care that he wrote a large portion of a book about it, is actually a living refutation of his claims about irreducible complexity. It has a system for building a flagellum that is reducible, which Michael Behe says doesn’t exist. What’s worse, Dr. Behe doesn’t seem to know about this.
In my opinion, Dr. Behe should read about the organisms he writes about, before he writes about them. In doing otherwise, he has failed inexcusably. By claiming that all cilia and flagella require IFT in order to be made when this isn’t true, Dr. Behe has failed inexcusably.
. . . or Inexcusable Failure, Squared?
So, to recap: Dr. Behe says that all flagella and cilia in cells that have nucleuses require IFT. They don’t. For Dr. Behe, that’s inexcusable failure.
Furthermore, malaria itself, the very organism that Dr. Behe claims is proof of ID, doesn’t have IFT. Dr. Behe apparently doesn’t even know this. This, too, is inexcusable failure on his part. That’s inexcusable failure, squared!
50. Behe, The Edge of Evolution: The Search for the Limits of Darwinism (New York: Free Press, 2007), 93.