24 June 2010

Introns. Let's think about this, people. Part I.

It's time to talk about introns and function, so at least the ID people and I can agree on what we're disagreeing about. First, though, a little housecleaning.

When confronting the avalanche of misinformation on so-called "junk DNA" from intelligent design creationists, it can be hard to know where to start. In a previous series, I addressed many of the falsehoods that are employed by these folks, but the basic outline of the problem is easy to lose in the fog of confusion that ID advocates and other creationists purposefully generate around the issue. You can learn all you need to know by reading the previous series, and by reading the extensive work of Ryan Gregory. But here's a brief re-introduction.

I would say there are two main components to the "junk DNA" misinformation effort.

1. ID advocates and other creationists claim that "Darwinists" assumed that non-coding DNA was functionless, right from the moment it was discovered. And so scientists failed to study non-coding DNA, leading to a vast knowledge gap that has cost human lives.

2. ID advocates and other creationists claim that "Darwinists" still assume that all non-coding DNA is functionless.

(Now, note that I won't even deal with the counter-claim, the only one that should matter for someone truly trying to establish an explanatory role for design: that genomic elements show properties that one would expect in a designed system. Plenty of ID advocates say that genomes look efficient and brilliant and excellent, but they're not so good at explaining exactly how genomic structures display the relevant characteristics. That's for another time.)

Back to those two components. They're both falsehoods.

Let's look at the first point. Read Ryan Gregory on the history of scientific thought on the subject: biologists did not make that assumption, indeed there was diversity of opinion on the amount of function in non-coding DNA from day one. Moreover, Darwinists were and still are most likely to postulate function for most genomic elements, since they were and are more likely to ascribe biological features to adaptation. And worse, the claim that non-coding DNA was ignored for decades is demonstrably false. I'm afraid it doesn't matter that some science writers (and one confused biologist) claim otherwise. There have surely been changes in attitudes toward genomic structures of various kinds as genomes have become so much better known. But the claim that biologists always assumed that all non-coding DNA is junk is just flat wrong, and you can read the bloody scientific literature yourself to see why.

And now the second point. Every time a cool new microRNA turns up in an intron, or a retroviral sequence is found to comprise a structural gene, or a pseudogene is shown to influence gene expression, ID propagandists go bananas as though they've just overturned evolutionary theory. Why? Because they seem to actually believe that "Darwinists" (by this they mean people who accept evolutionary theory in just about any of its forms) still think that non-coding DNA is all junk. The reality of current controversies in genomic structure and evolution couldn't be more different. Some hard-core adaptationists (the truest "Darwinists") share ID's commitment to the notion that genomes should contain very little non-functional debris, and you can learn a lot about the mendacity of ID mouthpieces by reading the disagreements between Larry Moran and his Darwinist detractors.

So, let's learn a little about introns. It should be fun. But don't fall for the misinformation from the propaganda network. In fact, think of "junk DNA" as an integrity dipstick. If you see those falsehoods on the dipstick, you're probably reading propaganda or uninformed nonsense. Caveat lector.

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