Over at the Panda’s Thumb, there is a sharp rebuttal of the creationists’ complaint about junk DNA. Read it, it’s useful. It leads to a bothersome and more general point, though.
Despite its connotations, the phrase “junk DNA” (originated by Susumu Ohno in 1972) does not intend to convey an absolute and irreversible lack of function. Indeed, as it is often noted, had that been the case “garbage DNA” would have been a better term. In fact, “junk” is what accumulates in people’s basements and attics, not immediately useful but not nasty or burdensome enough to be quickly discarded – indeed, something that may occasionally be found to be of use (at least, that’s what I tell my wife). Another problem with the term is that it is unfortunately often misused (in the lay press and especially by Creationists, although some scientists are guilty as well) to simply denote DNA that does not directly encode any protein sequence – which is absolutely wrong. It has long been known, in some cases even before the term was coined, that DNA contains important non-coding elements involved in gene transcription (e.g. the promoter and enhancer elements mentioned above), RNA splicing and polyadenylation, chromosome dynamics, etc. In addition, instances exist where the sequence of a particular stretch of DNA is irrelevant, but its presence may be important, as in the case of introns, certain “spacer’ regions, and so on. Still, while it is clear that the term “junk DNA” should be used advisedly (if at all) there are good reasons to think that large swaths of the genome of most eukaryotic organisms are indeed non-functional, in part because these stretches of DNA accumulate mutations neutrally, and diverge much faster than known functional elements, and also because vast differences in DNA amount, presence of large duplications/deletions of intergenic regions, as well as gain and loss of specific pseudogenes are often observed in closely related organisms (see again Ian’s piece).
There’s something about the whole concept of junk DNA that sets creationists to gibbering; it’s something of a touchstone subject. Similarly, vestigial organs and the whole idea of chance playing a role in biology are offensive to them and will set them off, because the idea that there exists things without intent or purpose is anathema. That Collins interview in Salon has something similar:
Well, this gets at what I think is actually the more serious challenge that evolution poses to religious faith — the whole business of random genetic mutations. Certainly, many evolutionists have argued that there is no inherent meaning to the course of evolution. It could end up any which way, and the fact that human beings ever evolved was blind luck. Without the asteroid that wiped out the dinosaurs 65 million years ago, it seems unlikely that large mammals, and eventually humans, would have ever evolved. Isn’t this a problem for religion?
I don’t think so. I can see the arguments that you just voiced and why they trouble people. But they are based upon the idea that God has the same limitations that we do. We cannot contemplate what it is like to be able to affect the future, the present and the past all at once. But God is not so limited. What appears random to us — such as an asteroid hitting the earth — need not have been random to Him at all. And in that very moment of creation, being as He is, outside of the time limitations, he knew everything, including our having this conversation. As soon as you accept the idea of God as creator, then the randomness argument essentially goes out the window.
The fear that the purpose in your life is your responsibility, that it is your job to provide intent and meaning and that there is no higher being who will tell you what to do, is one of those defining differences between theists and atheists, I think. I embrace the idea that I must find my own purpose; Christians like Collins dread it, and it leads them to invent ridiculous ideas like his all-knowing god and a predestined universe, where every coin flip is predetermined and lorded over by the all-knowing eye of an omnipotent sky-father. It’s rather disturbing to see an eminent molecular biologist and geneticist retreating so fearfully from the notion that genetic mutations are random.