September 05, 2007

Irreducible Complexity Reduced Again

In the genome of every human being are a number of stretches of code that we share in common with our evolutionary ancestors. Some of these stretches are very old, indeed, having survived without a single substantial alteration since the days of the earliest mammals. These ultraconserved regions are exactly the same in mice, rats and people. They are absolutely identical and perform the same functions in all mammals, and research is ongoing to learn more about them.

That's where some researchers looking at four of these ultraconserved regions enter the picture. They have investigated what happens when four of these elements are removed from the rodent genome. As it turns out, not much at all. They have published a paper entitled Deletion of Ultraconserved Elements Yields Viable Mice in which they demonstrate that loss of these elements isn't a death blow and theorize a bit about why it should be that such perfectly-conserved genes shouldn't be all that crucial to living things. They offer a couple of possible explanations, but the most plausible to my mind is that the phenotypic changes are compensated for over long stretches of time by natural selection. In other words, the changes to the organism in which mutation occurs aren't enough to bring down the wrath of selection against them, as it were, and it simply takes a very long time for the change to be bred back out of populations. It's very interesting work that provides some intriguing insight into the way that evolution works at the molecular level, and I humbly suggest that those who don't want to read a dry scientific paper at least have a look at the press release and interview on EurekAlert.

One of the tenets of Intelligent Design Creationism is Michael Behe's pet hypothesis (not a theory; a theory requires investigation, which Behe hasn't done) of Irreducible Complexity, part of which is the notion that complex structures must have been designed because change or loss of one part results in a non-functioning machine. In this study, regulatory genes, part of an extremely complex system, are lost... and the system manages to compensate. It's complexity reduced, without doubt. The study also points up another IDcreationist bit of misinformation, that organisms bearing deleterious mutations are selected against and, since the majority of mutations are negative (not true, but that's what they say), there cannot be spontaneous mutations serving as a basis upon which natural selection can work. In the study cited, we have mutations that are much more profound than what is typically seen in nature that take place in parts of the genome that life has apparently put a good deal of energy into maintaining unchanged for many, many millions of years, and yet life does go on when they are lost altogether, the resultant changes to the organisms being so small that reproduction is still possible and selection acts over a very long stretch of time. In other words, even bizarre mutations don't have to mean the end of the line for a population.

This is some very potent evidence in favor of evolutionary theory and against the fundamentals of Intelligent Design Creationism. I wonder whether Behe and his bunch will address this work or simply wave it all away, once again moving the goalposts somehow in order to pretend that this new knowledge somehow supports what they were saying all along. I doubt that they'll do what real scientists do and revise or discard their favorite hypotheses, in any case. I doubt we'll ever see the day when Michael Behe comes out and says, "I was wrong about the whole thing. Ah well, back to the lab!"

Sphere: Related Content