Andrea Bottaro posted Entry 1108 on June 2, 2005 03:10 PM.
Trackback URL: http://www.pandasthumb.org/cgi-bin/mt/mt-tb.fcgi/1106
In the Inferno, Dante tells the story of Count Ugolino della Gherardesca (don’t even try to pronounce it, unless you are Italian). Count Ugolino was locked up in a tower with his sons, without food or water, by his Pisan political enemies, whom he had betrayed. To survive, he ate his own children (he died anyway, and got to spend eternity stuck in a frozen lake, gnawing at his incarcerator’s skull).
Michael Behe also had to face Ugolino’s choice: starving for support for ID, he was forced to eat his own brain-child, “irreducible complexity” (IC). The meal was fully consumed in Behe’s response to my “The Revenge of Calvin and Hobbes” post.
Dr. Behe claims that the only evidence that would convince him of the evolution of an IC system consists not only of a complete step-by-step list of mutations,
… but also a detailed account of the selective pressures that would be operating, the difficulties such changes would cause for the organism, the expected time scale over which the changes would be expected to occur, the likely population sizes available in the relevant ancestral species at each step, other potential ways to solve the problem which might interfere, and much more.
Michael Behe, “Calvin and Hobbes are alive and well in Darwinland”
(For those who are wondering what that “much more” might even be, let me offer another prognostication: if an IC system was shown to have evolved to the level of detail demanded by Behe, his next step back would be to demand an account that each individual mutation was truly random with regard to fitness, as opposed as “poofed in” by the Designer. The ID goalposts have well-oiled wheels.)
But does this demand even make sense with respect to IC? It is worth remembering that IC, the ID advocates hoped, was supposed to be the silver bullet that takes out “Darwinism”, the one answering Darwin’s own challenge:
If it could be demonstrated that any complex organ existed, which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down.
Charles Darwin, “On The Origin of Species”, Chapter 6, “Modes of Transition”
There is, Behe and the ID advocates argued, something intrinsically special about IC, that makes it particularly impervious to Darwinian explanations.
An irreducibly complex system, if there is such a thing, would be a powerful challenge to Darwinian evolution.
Michael Behe, Darwin’s Black Box, p. 39
Indeed, Dr. Behe has no problem at all with Darwinian explanations as they apply to other, not irreducibly complex systems. For instance, Behe accepts that hemoglobin (the protein complex that carries oxygen in red blood cells) evolved from a myoglobin-like homologue (myoglobin is the protein that stores oxygen within muscle fibers). Here’s what he said about this:
The question is, if we assume that we already have an oxygen-binding protein like myoglobin, can we infer intelligent design from the function of hemoglobin? The case for design is weak. The starting point, myoglobin, can already bind oxygen. The behavior of hemoglobin can be achieved by a rather simple modification of the behavior of myoglobin, and the individual proteins of hemoglobin strongly resemble myoglobin. So although hemoglobin can be thought of a system with interacting parts, the interaction does nothing much that is clearly beyond the individual components of the system.
Michael Behe, Darwin’s Black Box, p. 207
Behe even goes on to compare hemoglobin to the “man in the moon”: suggestive of design, but almost certainly an illusion.
But wait a minute: does Behe have in hand the list of mutations that occurred on the path from myoglobin to hemoglobin? Does he have “a detailed account of the selective pressures that would be operating, the difficulties such changes would cause for the organism, the expected time scale over which the changes would be expected to occur, the likely population sizes available in the relevant ancestral species at each step, other potential ways to solve the problem which might interfere, and much more”? You can try asking him, but I doubt it. The reason why Behe has no qualms with the evolution of the hemoglobin system is that it makes sense. The available evidence for precursors, intermediates and their functions, partial as it is, is sufficient to conclude that known, well-characterized evolutionary processes were responsible, as opposed to supernatural intervention. It really doesn’t matter what every single amino acid substitution did in the long-extinct critters that evolved hemoglobins: only someone incompetent of biology, or an unrepentant Creationist, would require that level of detail. Behe knows that’s absurd.
That Dr. Behe asks for such an unnecessary level of detail for the evolution of the immune system (or any other IC system) carries two implications. First, it essentially reduces the concept of “irreducible complexity” to just a special case of evolution incredulity in general. Arguments from incredulity never go away (see Behe’s “and much more”, discussed above). In the case of evolution, we cannot have a mutation-by-mutation, selective-step-by-selective-step of pretty much anything, because the evidence cannot work that way, just like the evidence for plate tectonics can never be an inch-by-inch historical account of all the relevant forces involved in the motion of continents after the break-up of Pangea, or in the rise of the Himalayas.
Even when we can make a very strong inference of selective effects on a protein?s evolution (like in this case), we are still stuck with a level of detail that cannot compare to the absurd detail Behe is demanding.
By insisting on a degree of evidence for IC systems’ evolution that even evolutionary accounts of much simpler systems cannot provide, Dr. Behe has therefore effectively conceded that the concept of “irreducible complexity” is utterly meaningless: there is nothing special about IC systems, they just look fancy. In other words, it is not the “multiple, necessary, interacting parts” that make IC something that supposedly resists darwinian interpretations - it is amino acids, selective pressures, effective population sizes, like every other protein. Sic transit…
To get a sense of how silly the argument actually becomes, consider the following. Below is an alignment of the simple, 30-amino acid B peptide of insulin in a few species. Many positions match, some do not.
10 20 30 ------------------+-------------------+-------------------+- 1 F V K Q H L C G P H L V E A L Y L V C G E R G F F Y T P K S rat 1 . . N . . . . . S . . . . . . . . . . . . . . . . . . . . T human 1 . . N . . . . . S . . . . . . . . . . . . . . . . . . . . T elephant 1 A . N . . . . . S . . . . . . . . . . . . . . . . . Q . . A blackbird 1 . D N . Y . . . S . . . . . . . M . . . D . . . . . S . R . frog 1 A P A . . . . . S . . . . . . F . . . . . . . . . F N . D T elephantnosefish 1 R T T G . . . . K D . . N . . . I A . . V . . . . . D . T K hagfish
With a little luck and hard work, we may be able to sample enough organisms to have, at least for some branches, a real mutation-by-mutation account of the evolution of peptide B. But no matter how we try, we will never have “a detailed account of the selective pressures that would be operating, the difficulties such changes would cause for the organism, the expected time scale over which the changes would be expected to occur, the likely population sizes available in the relevant ancestral species at each step, other potential ways to solve the problem which might interfere, and much more”. Why is insulin peptide B less of a challenge for Darwinian evolution than the adaptive immune system?
Behe himself had summarized in his book what he saw as the insurmountable problem of immune system evolution - not amino acids and selective forces, but:
In the absence of the machine [RAG1/RAG2], the parts [V, D and J gene segments] never get cut out and joined. In the absence of the signals [RSSs], it’s like expecting a machine that’s randomly cutting paper to make a paper doll. And, of course, in the absence of the message for the antibody itself, the other components would be pointless.
Michael Behe, Darwin’s Black Box, p. 130
This is the “problem” the current data largely address: despite Behe’s disbelief, there was a simple way that machine could be put together, by integrating a RAG-bearing transposon (which we now know exists) into an immunoglobulin-like immune receptor already under selection for diversity (which we now know exists). This single event, which bypasses all of Behe’s objections above, is actually no more complex than the transition from a monomeric myoglobin to an allosteric hemoglobin complex (“allosteric” is just a technical word for a protein that works by changing its shape). In fact, arguably it’s simpler.
But rather than admitting he was wrong, that the evidence for evolution of the adaptive immune system is solid, and strengthening by the day, Behe has chosen instead to sacrifice whatever significance IC ever had. He ate his own child, to survive another day.
The second issue with Behe’s argument goes back to my original Calvin and Hobbes post. In it, I was not trying to make the point that the study of the evolutionary origin of the immune system is over. Indeed, I said that thankfully there is much more to be learned. My point was to compare the lively and steadily progressing field of evolutionary immunology, in Calvin and Hobbes’s box, to the stale air inside the IC cabinet, in which all efforts are directed at keeping the door tightly shut. This really highlights the difference between the ID view of science, and what science actually is. ID is about absolute philosophical claims - it does not, cannot cope with the fact that science is a process. As a political movement, ID has no time to let science take its course - it must provide an ideologically satisfying answer right away, for its fund-raisers and activists, and defend it to the end. That is why scientists put their efforts into collecting data bit by bit, and ID advocates put theirs in revising definitions and raising the evidence bar to protect their claims from the new scientific data.
Even Behe now behaves more like a spin doctor than a scientist. Consider this: in his post, Behe repeats once again the canard that Russ Doolittle made a mistake referring to clotting factor-deficient mice a few years back (an accusation which was nicely debunked by Ian Musgrave right here on the Thumb). I am quite sure people have pointed out to Behe that his claim is false before. In fact, since we know ID advocates eagerly read the Thumb (it took Behe only 24 hours to respond to my previous post!), I doubt that Behe was unaware of Ian’s argument as he penned his latest reply. Assuming Behe now will likely read this post, can we expect him to cease propagating this falsehood? We’ll see.
Finally, Behe states that Orr and I “seem to think that because Darwinists’ fantastic claims are very difficult to support in a convincing fashion, they should be given a pass”. That’s simply ludicrous: just my own post described a decade worth of hard-earned experimental results (and that’s just the tip of the iceberg) from dozens of scientists, published in the very best scientific journals, supporting an evolutionary hypothesis that Behe had embarrassingly dismissed without a thought. Compare this level of effort and accomplishment to that of Behe’s and his fellow ID advocates’: in the same decade, they have put out not a single iota of a positive result for ID, while the Discovery Institute was throwing away Ahmanson’s millions at school board challenges and PR campaigns hailing the upcoming scientific revolution.
I’ll leave it to others to judge whether Behe’s words are more arrogant or ignorant. The real question to consider is: who is asking to be given a pass for “fantastic claims” here, those who are collecting data to support their hypotheses, or those who are running away from them?
Commenters are responsible for the content of comments. The opinions expressed in articles, linked materials, and comments are not necessarily those of PandasThumb.org. See our full disclaimer.