Re: [asa] flagella

From: David Opderbeck <dopderbeck@gmail.com>
Date: Wed May 23 2007 - 11:55:47 EDT

 *First, it provides a mechanism whereby the system can
be built. Secondly, it implies that an ancestral form got along just
fine without the full system in place.*

But an ur-gene doesn't itself explain the intermediate steps, which is where
the rub lies. I would agree that identifying an ur-gene is an important
step towards inferring a gradual development of the contemporary structure,
but it seems to me only a step, not a knock-out punch.

On 5/23/07, David Campbell <pleuronaia@gmail.com> wrote:
>
> > And whether there is a single ur-gene really doesn't say anything about
> > irreducible complexity one way or the other, does it? I never
> understood
> > Behe to be saying that multiple genes were poofed into existence.
>
> The duplication and modification of existing genes to create an
> "irreducible" system poses two problems for the claim of
> irreducibility. First, it provides a mechanism whereby the system can
> be built. Secondly, it implies that an ancestral form got along just
> fine without the full system in place.
>
> An example sometimes invoked in ID is the system of DNA translation.
> It uses a set of tRNAs (among other parts). However, some of the tRNA
> genes seem to derive ultimately from a common ancestral gene. This
> implies that something ancetral to all known modern organisms had a
> simpler system with fewer tRNAs (and correspondingly fewer types of
> amino acids).
>
> --
> Dr. David Campbell
> 425 Scientific Collections
> University of Alabama
> "I think of my happy condition, surrounded by acres of clams"
>
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Received on Wed May 23 11:56:01 2007

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