I think it gets much worse than that for anti-evolution thinkers. I regularly see certain old-earth creationists (e.g. the folks at Reasons To Believe) and design proponents (e.g. William Dembski) arguing that "junk DNA" (which includes, but is not limited to, the 45% of the human genome composed of mobile elements and their debris) is not "junk" but can have important functions. (The arguments of these critics are flawed in several ways, which I'll detail some other time.) While it's true that mobile elements have contributed to the formation of new genes from time to time, and are thought to be significant sculptors of genomic evolution, it's also true that mobile elements are indiscriminate in their jumping, and their continued hopping about is a documented cause of harmful mutation. Here, though, is a significant quandary for a design advocate considering a bird genome: if these mobile elements have important functions in the organism, then how is it that birds can get by with 1/4 as many of them as, say, squirrels? Why, if these elements have important functions in the organism, do bats seem to need far fewer of them than, say, rats? (The genome of the big brown bat is 40% the size of the genome of the aardvark. Hello!) It seems to me that these facts are best understood when one considers the possibility that most of this DNA is essentially parasitic, and that some types of organisms have benefited by restraining its spread. A "design" perspective with regard to genome size is just not helpful, and if that perspective insists on excluding common ancestry, then it's worse than worthless.I'm liking this guy. Thanks to Siris for pointing him out.
Wednesday, September 05, 2007
Great new science blog, Quintessence of Dust, by Stephen Matheson, an associate professor of biology at Calvin College in Michigan (critic of intelligent design arguments and a big Shakespeare fan).