Re: [asa] What would evidence for design look like?

From: Rich Blinne <rich.blinne@gmail.com>
Date: Sat Jul 05 2008 - 21:59:49 EDT

On Jul 5, 2008, at 6:51 PM, Collin Brendemuehl wrote:

> Pim asked a good question. "What would evidence for design look
> like?"
>
> So I'd like to propose this consideration:
>
> Behe would answer that design appears irreducibly complex.
> The problem is that, using model theory methods, any potentially
> irreducibly-complex
> component can simply be placed into a new model.
> And so it appears that the argument may never end.
>
> And that, it would seem, may represent a weakness in both ID/IC and
> Darwinian evolution.
> Why of ID/IC? Because they may never reach an end proof.
> Why of Darwinian ideas? Because more complex model would seem to
> require more time for each added complexity.

No. The time required is a function of genetic distance and not
complexity. For example the evolution Y pestis (the plague) from Y
pseudotuberculosis (which is still around BTW) involved the production
of biofilms that made sure that the flea did not defecate the microbe
out and thus the flea would feed continually on the host inoculating
more and more victims. The specific change involved the conversion of
a gene into a psuedogene. So, the genotype complexity went down even
though a new (lethal) ability was gained (phenotype complexity went
up). This is an example of negative or purifying natural selection.
There can also be positive or neutral selection. What kind of
selection occurs does not have a material effect on how long it takes.
Instead, what made this particular change happen quickly was that the
genetic distance was small (30 bp internal duplication in YPO2449 of
Y. pseudotuberculosis, resulting in a 10-aa insertion in an otherwise
identical protein making RCSa a pseudogene). One could even argue
whether this was an increase or decrease in complexity depending on
how you define it. On the other hand, the genetic distance allowed for
an estimate of how long the evolution occurred, in this case 20 kya.
This example also illustrates why irreducible complexity is not a
helpful concept even if you decouple it from anti-evolutionary rhetoric.

Reference: Sun et al. Experimental evidence for negative selection in
the evolution of a Yersinia pestis pseudogene. PNAS June 10, 2008.

Rich Blinne
Member ASA

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Received on Sat Jul 5 22:00:40 2008

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