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Säie: Demise of Intelligent Design -- from creationevolutiondebate@egroups.com

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From: magi AT iki PISTE fi (Marko Grönroos)
Newsgroups: talk.origins
Subject: Re: Demise of Intelligent Design -- from creationevolutiondebate AT egroups PISTE com
Date: 6 Nov 2000 11:47:32 -0500

WickedDyno <amg39 PISTE REMOVETHIS AT cornell PISTE edu PISTE invalid> writes:
> Here is another actual example that destroys the irreducible complexity
> argument. In 1997, a group of scientists decided to watch the evolution
> of human growth hormone (a protein) HGH in the lab.
....
> The researchers genetically engineered the genes to produce a receptor
> that had a detrimental amino acid deletion. This changed the shape of
> the receptor and the HGH no longer "fit," so the bonding could not
> occur.
>
> The scientists then randomly mutated the coding regions of the HGH
> gene, generating millions of different mutant combinations. The
> bacteria with the mutations that caused the new HGH to bind to the
> modified receptor were selected. Now get this, the random mutations
> generated a new version of HGH that bonded to the modified receptor one
> hundred times tighter than the original nonmutant version. This is now
> an irreducibly complex system - but it evolved.

I feel this is a rather weak example, because the IC system wasn't
evolved from scratch. Rather, the researches started with an IC
system, made a small error in it, and evolved a fix. It's not the same
thing as if the whole system had evolved from scratch.

It's about same if you had a lock and a key that fit. You "mutate" the
lock by displacing of the lock rings inside, so that the key doesn't
fit in it any more. Then you generate different mutant keys. If you
had 10 rings in the lock with 10 different settings each, you can
mutate the key in 10*10=100 different ways. Thus, finding the new
setting randomly has 1% probablity, which is easy. Now, when you
create a working key randomly, do you decide that you've just created
an IC system? Of course not. There's much much more in a lock and a
key than a single ring setting.

EXCELLENT ARTICLE OTHERWISE!

--
-- Marko Grönroos, magi AT iki PISTE fi (http://www.iki.fi/magi/)
-- Paradoxes are the source of truth and the end of wisdom

Howard Hershey <hersheyh AT indiana PISTE edu> writes:
> "Marko Grönroos" wrote:
> > WickedDyno <amg39 PISTE REMOVETHIS AT cornell PISTE edu PISTE invalid> writes:
> > > Here is another actual example that destroys the irreducible complexity
> > > argument. In 1997, a group of scientists decided to watch the evolution
> > > of human growth hormone (a protein) HGH in the lab.
> >
> > I feel this is a rather weak example, because the IC system wasn't
> > evolved from scratch.
>
> Evolution does not invent things from scratch either. It modifies
> pre-existing systems or duplicates of pre-existing systems to perform
> slightly different functions or have slightly different different
> properties.

Well, yes, but I was talking about this particular example, which
doesn't really illustrate that. Here the function of the evolved
protein stayed the same, which seems like a very easy task to do, if
you consider my lock-key analogy.

A case where _another_ receptor activation protein would have taken
the function of the previous one, would have been a much better
example. If we use the lock-key analogy again, the lock would have
first been altered so that the original key doesn't fit in any
longer. Then a pocket-knife or a fork might have evolved a nick that
would have opened the lock.

> So the above is a perfect example of the co-evolution of systems to
> produce a new 'system' with different properties (in this case
> significantly higher binding, which, in fact, might make the system
> less useful biologically -- most biochemical systems involve minimax
> compromises).

Yes, the new system had better binding properties, but the functions
of the proteins stayed the same. The researchers only forced the
activator-receptor system out of a local minimum, and it then evolved
to a better minimum. Very nice example of optimization, but not a very
good example of creation of IC.

--
-- Marko Grönroos, magi AT iki PISTE fi (http://www.iki.fi/magi/)
-- Paradoxes are the source of truth and the end of wisdom

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