Posted by: Dan | July 25, 2006

Revisiting Creationist Abiogenesis

Back in March, on my original blog, I mentioned the Creationist arguments on abiogenesis, and perhaps it’s time to revisit just how bad a claim that is, since it’s been brought up again in the Evolution and Design comments section.
abiogenesis

The discussion began about the math behind Dembski’s Specification “theory,” which of course relies on ignorance. The more we know about a process, the less Dembski’s estimates of specified complexity have any relevance.

And as such, Salvador and David have retreated to the origin of life, as a specified process – which is of course the motherload of yet-unexplained occurences in the history of life. David says:

Even an extremely optimistic estimate of 50% probability per gene family suggests probabilities less than 1/2^1000, which I think is a tad bit beyond Dembski’s Universal Probability Bound of 10^120!

Good luck in trying to showing abiogenesis to a minimum self reproducing cell within the UPB – AFTER which you get a chance to invoke the wonderous powers of natural selection.

In other words, he’s arguing that it’s improbable that abiogenesis, as understood by Creationists (left side of the image above) could have occurred. And he’d be absolutely correct. What he hasn’t done is refute the power of acid-base and organic chemistries to generated replicating polymers for natural selection to act upon.

But it sounded impressive the way he put it, chock-full of incredulity, didn’t it?

For completeness though, let’s repost the rest of my original piece:

Members of Cornell’s IDEA club on their recently-started blog, The Design Paradigm, are this time pointing to a recent PNAS article on the “Essential genes of a minimal bacterium.” The obvious implication is that, if the simplest known bacterium requires well over 200 genes to survive in modern laboratory conditions, with ample nutrients, etc., it’s inconceivable that it could have evolved from nothingness (a.k.a. that abiogenesis could have occurred without a Creator)?

This isn’t a recent argument, and has been addressed before, as laid out on this Talk Origins article:

Another claim often heard is that there is a “life sequence” of 400 proteins, and that the amino acid sequences of these proteins cannot be changed, for organisms to be alive.

This, however, is nonsense. The 400 protein claim seems to come from the protein coding genome of Mycobacterium genetalium, which has the smallest genome currently known of any modern organism [20]. However, inspection of the genome suggests that this could be reduced further to a minimal gene set of 256 proteins [20]. Note again that this is a modern organism. The first protobiont/progenote would have been smaller still [4], and preceded by even simpler chemical systems [3, 10, 11, 15].

As to the claim that the sequences of proteins cannot be changed, again this is nonsense. There are in most proteins regions where almost any amino acid can be substituted, and other regions where conservative substitutions (where charged amino acids can be swapped with other charged amino acids, neutral for other neutral amino acids and hydrophobic amino acids for other hydrophobic amino acids) can be made. Some functionally equivalent molecules can have between 30 – 50% of their amino acids different. In fact it is possible to substitute structurally non-identical bacterial proteins for yeast proteins, and worm proteins for human proteins, and the organisms live quite happily.

The “life sequence” is a myth.

The rest of the article debunks many of the surrounding claims concerning abiogenesis and the minimal gene set.

References:


Responses

  1. Right off the top, you could go with a pure RNA genome and toss out all enzymes specific to the construction of DNA.

  2. I think that vertical line in the left-hand drawing should be labeld “Poof”. Then you could expound on how there is a “Lack of Poof” in the evidence for Creationism, and how the “Burden of Poof” is on them to produce some positive evidence.

  3. … maybe…

    Did you see Salvador applying the oh-so-convincing “I-know-it-when-I-see-it” argument”? I was so tempted to respond with an “I know an idiot when I see it, too” response. ;-)

  4. I haven’t been following the specified complexity theread closely. I am not familiar with information theory.

    Mark Chu-Carroll takes on one of Dembski’s papers unrelated to evolution over at Good Math, Bad Math

  5. I used the Mushegian & Koonan reference in a report, and is it not true they doubted the survivability of the 256-gene microbe?

    But allowing that it could survive, we’ve still never observed abiogenesis, so does it not remain confined to conjecture, starting from materialistic presupposition?

    Even the “real” abiogenesis theory seems to apply to Dembski’s specified complexity criteria. Have all observed examples of that trait thus far had an intelligent source? Although they may not call it specified complexity, does SETI not use this concept?

  6. Ivy privy: Is there not a lack of proof for abiogenesis?

    On the other hand, all positive evidence thus far shows that specified complexity (which living things exhibit) always has an intelligent source.

  7. Mikeb,
    Re: materialistic presupposition – if you insist on calling it that, fine. Scientists see it as a presupposition derived from physics and chemistry, however. That is, it is a presupposition based upon current knowledge. It is a necessary presupposition if one is to advance knowledge of natural history.


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