Pharyngula

It’s junk. Get over it.

Now, see, this is why you shouldn’t read a gadgets & fashion magazine for information on science. Wired has run an awful little article that breathlessly claims that junk DNA ain’t junk—it’s all got a purpose, because opossum junk DNA is different from human junk DNA (I know, that makes no sense at all, but there it is in the article).

Then, just to make it even worse, that non sequitur is followed up by bunch of “we knew it all along” quotes from creationists. And then they’ve got Francis Collins chiming in and saying that he doesn’t use the term “junk” because he thinks it’s all lying around in case there’s a future use for it. Gah. He’s supposed to know what he’s talking about; it sure doesn’t show whenever he opens his mouth.

Fortunately, Larry Moran shreds this one. In addition, one scientist who was quoted as saying something sensible in the article, T. Ryan Gregory, expands and clarifies his sole comment. It’s really too bad the writer didn’t spend more time with him than with Michael Behe.

Comments

  1. #1 David Marjanovi?
    September 16, 2007

    Junk DNA *could* mutate into useful DNA.

    Much junk DNA is junk because it misplaced a start or stop codon. The misplaced codon could mutate again and disappear (bringing back the original gene plus accumulated mutations), a mutation could provide a new codon in a position that produces a functional gene, or a mutation within the junk could provide a function.

    What I’ve read makes me think that these scenarios are not very likely, but they would be technically possible.

    This seems to be how you get secondarily winged stick insects.

    However, pseudogenes don’t make up a very large part of junk DNA (45 % are retrovirus/transposon corpses alone!), and because pseudogenes are not under selection, they are free to accumulate mutations that would make them dysfunctional even if the start & stop codons all came back in the right positions, so you’re right it’s not likely, and indeed it doesn’t seem to be common.