Recently the Intelligent Design community has become more obsessed with so-called junk DNA. Jonathan Wells has just published a book on it (The Myth of Junk DNA), and it comes up more and more in their discussions. Plenty of others have and will dissect all of the ways in which they misrepresent the science. Larry Moran does a good job at Sandwalk (search for Junk DNA). I am interested in how this emphasis is a surprising change from the usual creationists tactic. At first it seems like they are actually trying to be a science.

First I should say a little bit about the misrepresentations going on. "Junk DNA" never really was a recognized term. It includes a wide variety of DNA. Creationists try to make it refer to everything except protein coding DNA. There has never been a time that biologists thought all non-coding DNA is junk. We have always known about regulatory DNA and rRNA and tRNA, for example. Much of our DNA is selfish DNA, such as the various transposable elements. Some might consider this junk, some might not.

The most important thing to understand is that evolution does not predict the existence of junk DNA. It can explain it, but it does not require it. In fact, the existence of so much junk was a surprise at first, because many biologists had a strong adaptationist bias and assumed most structures (including DNA) have an adaptive function. One of the usual meanings of junk DNA is functionless DNA. Evolution can account for non-adaptive features and the existence of such DNA feeds into the question of how important selection is compared to other processes, such as genetic drift (selection will produce functional features, drift can produce functionless).

So the existence of junk DNA is not really an argument for evolution, since evolution neither predicts it nor denies it. It can explain it, which is necessary for any theory. Junk DNA may be an argument against design, as we will see below, but it is not a positive argument for evolution. The great strength of the junk DNA for evolution is not so much its existence, but the patterns that it forms. The presence of the exact same pseudogene inactivated with the same mutations in the same position is several organisms is strong evidence for common ancestry.

So now we get to the surprising part: the embrace of junk DNA denial by the ID movement. It appears that they have genuinely embraced a prediction. They are saying that ID predicts there will be no junk DNA. They admit its existence is a genuine problem for ID. If that is the case, then they are admitting the existence of junk DNA is a way to falsify ID.

Why would ID predict there would be no junk DNA? If you assume a logical, optimal designer, like a human engineer, who would not make wasteful or useless features, then junk DNA is a problem. Junk DNA is clearly not good engineering. So if ID predicts no junk DNA, it based on a particular version of the designer. This is a breakthrough. ID is very careful not to say anything specific about the designer, but they now seem to have done so. I wonder if they will stick with it.

Junk DNA is just one version of a common argument against creationism. There are various arguments that show evidence of poor design in nature. For example, the vertebrate eye is poorly designed in many ways--light has to pass through nerves and blood vessels to get to the photoreceptors and it has a blind spot. It is not good engineering. The panda's thumb is another classic example of an oddly designed object. Vestigial organs are similar, and analogous to junk DNA (some of it is "vestigial DNA").

How have ID proponents responded to these arguments? Sometimes they argue that the features are well-designed, but they eventually almost always fall back on the mysterious designer argument. Who are we to tell the designer how to design? God may have had some mysterious purpose. He may even have been whimsical. We cannot expect the designer to be like a human designer or engineer. If God wanted to give the panda a thumb made out of a wrist bone he could have, and just because it seems odd to us means nothing. We can't dictate how the designer designs.

When they make that argument, they move out of science and into the land of the unflasifiable. Although well designed things are evidence for a designer, poorly designed things are not evidence against the designer. The designer can make whatever he wants. The designer can be an optimizer or engineer, or he can be whimsical and mysterious. Therefore, no observation is inconsistent with design. ID actually can be a theory that makes predictions, but only if they dare to pin the designer down, and clearly say what kinds of things a designer would and would not do.

Generally, ID has not been willing to do that. All of the many examples of poor design mean nothing. For some reason, they don't do that with junk DNA. They seem to actually be saying that the designer would not make junk DNA. The designer is an optimizer, an engineer. They have pinned him down and made a prediction. If we take them at their word, ID is now testable. If much of our DNA has no function, then we have disproven ID.

It would be great if they stuck to this. The history of the movement isn't too promising. I suspect one of two possible outcomes. Either they will forever deny the evidence for junk DNA, as Wells is doing now, or they will eventually go back to the mysterious designer argument. They are good at denying clear evidence. They have denied the clear evidence of the fossil record for decades. The first tactic should work for quite awhile, but eventually they may switch to the second choice and invoke the mysterious purposes of the designer. I guess there is a third choice--treat it as a genuine prediction and reject ID when the prediction fails. I'm not holding my breath.

It seems to me that accepting the threat of junk DNA also opens ID up to the classic argument from bad design. They have nailed down their designer. He is an optimizer. Now the structure of the eye, the panda's thumb, or the recurrent laryngeal nerve are all arguments against ID. If God wouldn't make junk DNA, he wouldn't make any of them either. If an ID proponent makes an argument about junk DNA, the first thing you should do is to confirm that they are admitting the designer would not make such non-adaptive, non-optimal features.