Introns and Design

Over at his blog, Steve Matheson has been reviewing Stephen Meyer’s book, Signature in the Cell. Matheson quotes Meyer:

..the original DNA text in eukaryotic organisms has long sections of text called “introns” that do not (typically) encode proteins. Although these introns were once thought to be nonfunctional “junk DNA,” they are now known to play many important functional roles in the cell.

And replies:

Here’s a short explanation for why Meyer’s statement is ludicrous. The human genome contains at least 190,000 introns (though it’s been recently estimated to contain almost 210,000). Together those introns comprise almost 1/4 of the human genome. One fourth. That’s 768 million base pairs. And biologists have identified “important functional roles” for a handful of them. How many? Oh, probably a dozen, but let’s be really generous. Let’s say that a hundred introns in the human genome are known to have “important functional roles.” Oh fine, let’s make it a thousand. Well, guys, that leaves at least 189,000 introns without function, and gosh, they’re snipped out of the transcripts and discarded before the darn things even leave the nucleus.

I would agree with Matheson that it is highly unlikely that a couple hundred thousand introns each have an “important functional role” “in the cell.”  But I’d like to take the topic of introns and steer it into a much more interesting teleological direction.

Let me propose a hypothesis that flows naturally from the hypothesis of front-loading evolution: introns facilitated the evolution of metazoan life.

To this end, I have created the ‘introns’ tag and will be periodically exploring this hypothesis from several angles over the next few weeks/months.

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4 responses to “Introns and Design

  1. Oh good. I gave Prof. Matheson a copy of your book a couple of years ago. Now maybe the two of you can have a constructive dialogue.

  2. GringoRoyale

    I find Matheson’s response alittle odd.
    I haven’t read Meyer’s books, aside from that section quoted.
    In reading the section I didn’t really come away with the thought that all introns are as meaningful as exons. Maybe that’s because I have some background knowledge on introns, exons and historical views on the former with respect to the latter.
    But there was a view that introns were simply vestigial, irrelevant.
    Overtime that stance has been, to some extent, overturned.

    Matheson might find Meyer’s comment ludicrous…. but certainly not as ludicrous as reading something into the text that isn’t there and then bashing the object of that approach.

    I would hope Matheson wouldn’t take the position that we are omniscient now to the fact that those other 189,000 in which we haven’t seen function do not have any function worth being concerned about.
    Because that would be….. how should I say this???? ludicrous?

  3. That’s a good point, Gringo, as Matheson seems to be reading something into that excerpt from Meyer. Consider what Meyer claims:

    ..the original DNA text in eukaryotic organisms has long sections of text called “introns” that do not (typically) encode proteins. Although these introns were once thought to be nonfunctional “junk DNA,” they are now known to play many important functional roles in the cell.

    How is this all that different from the following claim?

    Previously regarded as “junk DNA,” it is becoming increasingly clear that nuclear introns may serve a diverse range of functions.

    From: Sullivan, J. C., Reitzel, A. M. & Finnerty, J. R. 2006. A high percentage of introns in human genes were present early in animal evolution: evidence from the basal metazoan Nematostella vectensis. Genome Inform. 17, 219–229.

    The difference seems to be merely a matter of the strength of the contention. Meyer claims many important functional roles in the cell are “known” while these scientists claim a diverse range of functions “may” exist.

  4. Pingback: Intron Reply «

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