Pharyngula

Another nail driven into poor Behe

Another review of Behe’s book, The Edge of Evolution, has been published, this time in Nature and by Ken Miller. This one focuses on Behe’s central claim, that he has identified a probabilistic limit to what evolution can do that means no differences above roughly the genus level (and in many cases, the species level) can be generated by natural mechanisms. This is his CCC metric, or the probability of evolving something equivalent to the “chloroquine complexity cluster”, which he claims is the odds of evolving two specific amino acid changes in a protein. It’s a number he pegs at 1 in 1020, right at the edge of what a large population of protists can do, but beyond the reach of what a smaller population of slowly reproducing metazoans, like hominids, could hope to accomplish even with geological time limits. It’s the same problem I addressed in my earlier criticism, although Miller manages to slap it down with much greater brevity.

Behe cites the malaria literature to note that two amino-acid changes in the digestive-vacuole membrane protein PfCRT (at positions 76 and 220) of Plasmodium are required to confer chloroquine resistance. From a report that spontaneous resistance to the drug can be found in roughly 1 parasite in 1020, he asserts that these are the odds of both mutations arising in a single organism, and uses them to make this sweeping assertion:

“On average, for humans to achieve a mutation like this by chance, we would need to wait a hundred million times ten million years. Since that is many times the age of the universe, it’s reasonable to conclude the following: No mutation that is of the same complexity as chloroquine resistance in malaria arose by Darwinian evolution in the line leading to humans in the past ten million years.”

Behe, incredibly, thinks he has determined the odds of a mutation “of the same complexity” occurring in the human line. He hasn’t. What he has actually done is to determine the odds of these two exact mutations occurring simultaneously at precisely the same position in exactly the same gene in a single individual. He then leads his unsuspecting readers to believe that this spurious calculation is a hard and fast statistical barrier to the accumulation of enough variation to drive darwinian evolution.

It’s a painfully basic error — Behe is counting on his readership being unaware of basic principles in probability and on having no knowledge of the actual, relevant research on this problem. It’s a safe bet for him, from what I’ve seen of the fans of ID. Unfortunately, when real scientists take a look at what he’s saying, they can see everywhere that he went wrong.

Behe obtains his probabilities by considering each mutation as an independent event, ruling out any role for cumulative selection, and requiring evolution to achieve an exact, predetermined result. Not only are each of these conditions unrealistic, but they do not apply even in the case of his chosen example. First, he overlooks the existence of chloroquine-resistant strains of malaria lacking one of the mutations he claims to be essential (at position 220). This matters, because it shows that there are several mutational routes to effective drug resistance. Second, and more importantly, Behe waves away evidence suggesting that chloroquine resistance may be the result of sequential, not simultaneous, mutations (Science 298, 74?75; 2002), boosted by the so-called ARMD (accelerated resistance to multiple drugs) phenotype, which is itself drug induced.

A mistake of this magnitude anywhere in a book on science is bad enough, but Behe has built his entire thesis on this error. Telling his readers that the production of so much as a single new protein-to-protein binding site is “beyond the edge of evolution”, he proclaims darwinian evolution to be a hopeless failure. Apparently he has not followed recent studies exploring the evolution of hormone-receptor complexes by sequential mutations (Science 312, 97?101; 2006), the ‘evolvability’ of new functions in existing proteins ?; studies on serum paraxonase (PON1) traced the evolution of several new catalytic functions (Nature Genet. 37, 73?76; 2005) ?; or the modular evolution of cellular signalling circuitry (Annu. Rev. Biochem. 75, 655?680; 2006). Instead, he tells his readers that there is just one explanation that “encompasses the cellular foundation of life as a whole”. That explanation, of course, is intelligent design.

This is a trend for Behe. Both of his popular books that have fed the Intelligent Design movement have relied on gross ignorance and misrepresentation at their core. One has to cringe a little bit to see it: Behe really seems to believe that he has had a deep insight into a real problem with evolution, and it’s really nothing but a deep mistake on his part…and he keeps digging his hole deeper.


Miller KR (2007) Falling over the edge. Nature 447:1055-1056.

Comments

  1. #1 Blake Stacey, OM
    June 27, 2007

    Ha! I was there first:

    First, we already know that CQR doesn’t appear via “independent changes,” but that the evidence strongly suggests it can arise through successive steps, each one conferring a little benefit until the final version can blow the competition away. Second, Chen et al. (2005) showed that the mutation at position 220, changing alanine to serine, is not necessary for chloroquine resistance. It’s common in CQR parasites around the world, but some P. falciparum caught in the Philippines show no mutation at position 220, and other mutations at positions 144 or 160 instead.

    At any rate, off I go to add Miller’s review to the list.

  2. #2 Blake Stacey, OM
    June 27, 2007

    Dang it, I’ve added Miller to the list, but the article is behind a subscription wall!

  3. #3 CalGeorge
    June 27, 2007

    Dawkins reviews this weekend in the N.Y.Times.

    Just got the preview:

    I had expected to be as irritated by Michael Behe’s second book as by his first. I had not expected to feel sorry for him. The first — “Darwin’s Black Box” (1996), which purported to make the scientific case for “intelligent design” — was enlivened by a spark of conviction, however misguided. The second is the book of a man who has given up. Trapped along a false path of his own rather unintelligent design, Behe has left himself no escape. Poster boy of creationists everywhere, he has cut himself adrift from the world of real science. [continues]

  4. #4 ERV
    June 27, 2007

    Amedeo Henry– Why wouldn’t Demski with a Ph.d. in Mathematics catch a basic error such as this?

    *shrug* Probably the same reason why Behe with a PhD in biochemistry didnt/doesnt catch basic biochemistry errors.

    CalGeorge– Dawkins should know better than to feel sorry for these leeches. On a humorous note, from Dawkins description, it appears Behe has become trapped at a local fitness maxima. I suppose that can happen when youre a one dimensional character.

    Blake– You missed one of mine :P ‘Behe vs HIV’

  5. #5 Torbjörn Larsson, OM
    June 27, 2007

    Paul:

    I don’t know if you have read PZ’s post, but most of the facts are from Ken Miller’s review of Behe’s book. And if you don’t think much of biologist PZ Myers professional expertize for some unsupported reason, Ken Miller is a renown biologist.

    For example, Ken Miller has written books on biology including a textbook and he was a biology science expert witness in the Dover trial. He was rewarded with the American Society for Cell Biology 2006 Public Service Award along with Barbara Forrest:

    Miller was recognized for his outstanding dedication to, and defense of, science and science education against the threat of Intelligent Design. Forrest was selected for her dedication and tireless efforts to expose the motives behind the Intelligent Design movement. Both Forrest and Miller were also acknowledged for the critical roles they played in the landmark evolution case, Kitzmiller v. Dover. [Ref: See link to pdf in link above.]

    he didn’t overlook the existence of other chloroquine resistant strains […] He didn’t disregard sequential mutations

    As noted, he overlooked them in his calculation, which is what matters for the result he claims.

    You are playing high and loose with your definition of “fact”.

  6. #6 Torbjörn Larsson, OM
    June 27, 2007

    Paul:

    If chloroquine resistance was easy to achieve, for example, wouldn’t we expect to find a range of different malaria populations, with different solutions?

    “… resistance to chloroquine has appeared fewer than ten times in the whole world in the past half century” (Behe, from Edge of Evolution.)

    And, more importantly, malaria is one of the greatest evolutionary forces on humans in recent history. Different versions of sickle cell anemia has developed 4 (!) times in humans since it confers resistance ( see http://en.wikipedia.org/wiki/Sickle_cell_anemia and especially the maps).

  7. #7 Torbjörn Larsson, OM
    June 27, 2007

    Paul:

    [Continuing pga linkfest vs spamfilter…]

    If malaria evolution is so important for Behe, how come he disregard the human component in the system? Is it because the changes are so drastic, perhaps?

    Malaria is thought to have been the greatest selective pressure on the human genome in recent history.

    ( http://en.wikipedia.org/wiki/Malaria )

    Other established new traits securely or tentatively associated with malaria resistance are the set of thalassemias, non-expression of Duffy antigens, and changes in G6PD, HLA, and IL4 molecules.

    In summary I can’t find a single fact you have correct. Shouldn’t that be important for you since you are interested in “fairly characterising [sic]” things?

  8. #8 David Marjanovi?
    June 27, 2007

    Guys, quick question: Isn’t Miller backing away from _single,_ sequential, changes in his review? Isn’t the backbone of darwinism _single,_ advantageous changes?

    I don’t understand what you mean, Paleyist.

    Miller is the one who mentions that there’s evidence that chloroquine resistance is the result of two sequential mutations instead of two simultaneous mutations.

    Evolution = descent with modification by mutation, selection, and drift. Mutation constantly produces variation, and selection narrows the variation down.

  9. #9 David Marjanovi?
    June 27, 2007

    Guys, quick question: Isn’t Miller backing away from _single,_ sequential, changes in his review? Isn’t the backbone of darwinism _single,_ advantageous changes?

    I don’t understand what you mean, Paleyist.

    Miller is the one who mentions that there’s evidence that chloroquine resistance is the result of two sequential mutations instead of two simultaneous mutations.

    Evolution = descent with modification by mutation, selection, and drift. Mutation constantly produces variation, and selection narrows the variation down.

  10. #10 David Marjanovi?
    June 28, 2007

    ….at least until this RNA thing is fleshed out a bit?

    Which RNA thing exactly? Textbooks today contain lots more knowledge about RNA than they did 10 years ago, and I know people working on RNA but not discovering any big surprises so far. Which great mystery are you talking about? ~:-| In other words, I don’t know how much you know, or perhaps rather how much you don’t know.

  11. #11 David Marjanovi?
    June 28, 2007

    ….at least until this RNA thing is fleshed out a bit?

    Which RNA thing exactly? Textbooks today contain lots more knowledge about RNA than they did 10 years ago, and I know people working on RNA but not discovering any big surprises so far. Which great mystery are you talking about? ~:-| In other words, I don’t know how much you know, or perhaps rather how much you don’t know.

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