Secrets of the Cell: Dr. Michael Behe

Arkycharlie

Super Member
Not just my observation. Behe's paper showed that a simple IC system could evolve in a small population of bacteria in about 20,000 years. This was confirmed by Behe's own testimony at the Kitzmiller trial shortly after the paper was published.
Define "simple" IC system. A couple of examples would be helpful.
 

Arkycharlie

Super Member
IDists have a long history of recycling the same nonsense again and again. As far as I can tell from the video, Behe is just trotting out arguments refuted long ago. We have discussed on CARM numerous times, see for example here:
I would define "refuted" as meaning scientifically disproven. If that's your definition, point me to a single example.
 

rossum

Well-known member
Define "simple" IC system. A couple of examples would be helpful.
So you didn't bother to read Behe's paper, to which I provided a link. Not a good look, I'm afraid.

However in order to save you the effort, here is what Behe says in the abstract (that is the opening of the paper, giving an overview):

Yet some protein features, such as disulfide bonds or ligand binding sites, require the participation of two or more amino acid residues, which could require several mutations. Here we model the evolution of such protein features by what we consider to be the conceptually simplest route—point mutation in duplicated genes.​

That "require the participation of two or more amino acid residues" is IC; if any of the required residues is missing then the disulfide bonds or ligand binding sites will not work. They are simple IC systems because of the "two or more", so the IC system may only have two essential parts, thus being simple.
 

The Pixie

Well-known member
I would define "refuted" as meaning scientifically disproven. If that's your definition, point me to a single example.
Again, I refer you to the Kitzmiller case. Behe claimed the blood clotting system is IC. A load of papers were presented that showed that it could nevertheless evolve. Even more evidence has since come to light that Behe was wrong.

But does the coagulation system even meet the definition of irreducible complexity? The answer is no. The clotting cascade consists of sequential activation of a series of proenzymes or inactive precursor proteins (zymogens) to active enzymes. There are two arms to the clotting cascade: intrinsic and extrinsic. Both converge on the common pathway, which ultimately promotes thrombin generation and fibrin formation.
Humans who are deficient in one or another zymogen often have bleeding diatheses, but many can live a normal life and reproduce.
...
By examining the genomes of various classes of extant vertebrates, it is possible to infer the evolutionary history of the coagulation system. We learn that the clotting cascade first arose in an ancestral vertebrate some 600 million years ago. Moreover, the clotting cascade, as we recognize it in humans, did not evolve all at once. The extrinsic system appeared first (in jawless fish), followed by FIX (in jawed fish) and then the contact system (in amphibians) (see Figure below). This sequence of events is backed by strong biological plausibility: clotting is always initiated by the FVII of the extrinsic cascade, is amplified by FIX of the intrinsic pathway and is further accelerated by FXI, which lies downstream of the contact pathway.

See also:


I have never seen anything to suggest Behe now accepts the blood clotting system is not IC, but to judge from here, IDists were still trotting out the blood clotting cascade as evidence for ID,

I would not be at all surprised to find it is in Behe's book. Perhaps you can say one way of the other?
 

Arkycharlie

Super Member
But does the coagulation system even meet the definition of irreducible complexity? The answer is no. The clotting cascade consists of sequential activation of a series of proenzymes or inactive precursor proteins (zymogens) to active enzymes. There are two arms to the clotting cascade: intrinsic and extrinsic. Both converge on the common pathway, which ultimately promotes thrombin generation and fibrin formation.
Humans who are deficient in one or another zymogen often have bleeding diatheses, but many can live a normal life and reproduce.
...
By examining the genomes of various classes of extant vertebrates, it is possible to infer the evolutionary history of the coagulation system. We learn that the clotting cascade first arose in an ancestral vertebrate some 600 million years ago. Moreover, the clotting cascade, as we recognize it in humans, did not evolve all at once. The extrinsic system appeared first (in jawless fish), followed by FIX (in jawed fish) and then the contact system (in amphibians) (see Figure below). This sequence of events is backed by strong biological plausibility: clotting is always initiated by the FVII of the extrinsic cascade, is amplified by FIX of the intrinsic pathway and is further accelerated by FXI, which lies downstream of the contact pathway.
I read the whole article from which you copied and pasted this verbiage into your response. I view that article as pure evolutionary fantasizing and you view it as settled science. That makes very clear the futility of these exchanges. There will never be a meeting of the minds on evolution vs ID in this forum and I have no interest in wasting my time in continuing to beat a dead horse. Time will eventually reveal the truth of the matter and I will just leave it there.
 

The Pixie

Well-known member
I read the whole article from which you copied and pasted this verbiage into your response. I view that article as pure evolutionary fantasizing and you view it as settled science. That makes very clear the futility of these exchanges. There will never be a meeting of the minds on evolution vs ID in this forum and I have no interest in wasting my time in continuing to beat a dead horse. Time will eventually reveal the truth of the matter and I will just leave it there.
Having read the article, are you still going to claim that evolutionary pathways to IC systems, defined as any system where you take away one part and it stops working, are not possible?

Further, are you willing to concede that the blood clotting cascade is not an IC system, given:

His 2008 paper [Doolittle et al, 2008] reports on a careful search through the lamprey genome. The lamprey, as luck would have it, has a perfectly functional clotting system, and it lacks not only the three factors missing in jawed fish, but also Factors IX and V.

As you say, there will never be a meeting of the minds on evolution vs ID, but why is that? With regards to this specific issue, is that because:
  • You have reason to believe that Doolittle's research is wrong
  • You can admit ID got it wrong on this one
  • You are just going to ignore evidence that refutes the claim of IC
From what I have seen of ID, I am guessing it is the third; I hope you will surprise me.
 
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