Michael Behe and the “Limits” of Evolution (Bacterial Edition). James Downard - 18 July 2014

Michael Behe and the “Limits” of Evolution (bacterial edition). James Downard - 18 July 2014 During the Kitzmiller v. Dover Intelligent Design trial in 2005, the Expert Testimony of Michael Behe (2005a) came under fire. One of the lynchpin figures in the design movement, famed for Darwin’s Black Box, his crash-and-burn performance has been amply covered in many venues, including popular coverage by Matthew Chapman (2007) and Laurie Lebo (2008). Overlooked in the heat over irreducibly complex bacterial flagella mousetraps (and whether Behe and Ken Miller would duel with lab beakers at dawn) was a minor technical issue tossed off in Behe’s deposition and afterward, which warrants examination for the insights it gives to Behe’s use of technical citation and the degree to which he investigates the strength of the ammunition he slips into his ID shotgun. Venturing into the finer points of bacterial antibiotic resistance, Behe was bowled over by the import of Barry Hall (2004a): “In Vitro Evolution Predicts that the IMP-1 Metallo-β-Lactamase Does Not Have the Potential To Evolve Increased Activity against Imipenem.” To emphasize this “limit of Darwinian evolution” Behe included a full reprint of it for the Dover court, where one could see that he had drawn a big circle around the “Not” in the title. Arbitrarily deck-stacking his point further by asserting that evolutionists think “Darwinian processes can do everything,” Behe (2005a) summarized Hall’s findings thus: This is exemplified in some recent papers from the laboratory of Professor Barry G. Hall at the University of Rochester. Although he is not an advocate of intelligent design, Professor Hall nonetheless does not automatically assume Darwinian processes can do everything. For example, he writes in a paper in the journal Antimicrobial Agents and Chemotherapy: “Instead of assuming that metallo-β-lactamases will evolve rapidly, it would be highly desirable to accurately predict their evolution in response to carbapenem selection.” Using a method he developed, he predicts that bacteria will be unable to develop resistance to an antibiotic called imipenem. He writes in the abstract of his paper: “The results predict, with >99.9% confidence, that even under intense selection the IMP-1 β-lactamase will not evolve to confer increased resistance to imipinem.” Behe (2005b) thought so much of this finding that he reiterated it in his rebuttal to Ken Miller, adding with bold conviction that “Barry Hall is looking to find the limits to evolution in order to help develop better antibiotics. I think this point deserves greatest emphasis. It is critical to the development of better antibiotics, pesticides and drugs to determine the limits of Darwinian evolution.” And Behe (2007, 236-237) rolled it out once again, followed by Jonathan Sarfati (2008) over at Answers in Genesis, freely drawing on The Edge of Evolution as authority to use Hall’s paper as a club to pound the New Scientist’s series by Michael LePage (2008a-y) on antievolutionary myths and misconceptions about evolution—an ironic maneuver on Sarfati’s part, since his secondary reliance on Behe had just added a new example of exactly the sort of defective analysis LePage was warning about, such as LePage (2008g) on “Evolution is limitlessly creative.” So what had Hall actually done, and how was all this playing out in that world of disease abatement that Behe was so anxious to liberate from the deadening shackles of Darwinian presumption? Hall had indeed pioneered useful techniques for evaluating the potential evolution of bacterial virulence in specific cases, summarized by Hall (2004b), which should have made Behe especially mindful of all the content of the paper, and not just the bits that served his apologetic purposes. For example, this paragraph earlier in Hall’s paper: IMP-6, which differs from IMP-1 by a single amino acid substitution, increases the MIC of meropenem 128-foldbut does not increase the resistance to imipenem. If the rapid evolution of the class A extended-spectrum β-lactamases is typical, then we should indeed be concerned about the evolution of metallo-β-lactamases in response to the clinical use of imipenem and other carbapenems. Hall (2004a, 1032). As the mutant cousin that generates the IMP-6 enzyme appeared not to be a problem (at the moment), Hall’s experimental modeling for the effect of varied mutation in the more commonly generated IMP-1 suggested there wouldn’t be an impending threat from that particular direction. But the existence of an “IMP-6” ought to have clued Behe in to the existence of more one player in the bacterial game. This turns out to be rather a consistent blind spot for Behe (1996), such as population biology issues or how many MHC molecules there were in the evolution of the vertebrate immunity system. In this area, though, Hall (2004a, 1033) had explicitly concluded with a warning: “In order to understand the risks posed by metallo-β-lactamases, it will be necessary to conduct similar studies on representative members of each of the three metallo-β-lactamase subfamilies and to include all clinically relevant carbapenems in those studies.” If the caricature that “Darwinian processes can do everything” is flawed, what of Behe’s implicit presumption at Dover (and since) that conditions applying to the genome of one of a broad group of related bacteria could be extrapolated into a fixed “limit of Darwinian evolution” precluding mutations in any of the many variants Hall had not studied concerning their generation of the metallo-β-lactamase (MBL) enzymes that could pose a threat to imipenem use? It is indicative of Behe’s approach to IMP-1 (and by analogy to a lot of the argument that goes on in the ID and creationist camps) that at no time did Behe stop to explain what was going on: why mechanistically IMP-1 would be unlikely to mutate in a way to threaten the utility of imipenem, or what were the dynamics of the system that weighed even slightly in favor of a design option. All he did was wave the isolated finding like a talisman to ward off the Darwinian boogieman. Following that unexplored thread suggests why Behe might not be the best fellow to rely on for recommendations on antibiotic policy. IMP-1 and IMP-6 were first isolated in Japan (in 1991 and 1996 respectively), but since discovered elsewhere and encountered in various bacterial species. The IMP family poses a threat because of the way the zinc ions in its MBLs act as a catalytic cofactor to bind to the antibiotics and so disrupt their function. The reason for special concern, though, is that the genes for them have come to be attached to very active plasmids via integrons (genetic modules able to capture gene cassettes in their recombination process) as well as in “copy me” transposons, Yano et al. (2001) and Toleman et al. (2003), offering the potential for fresh mutational mixes that might not be so congenial to imipenem, such as IMP-4 showing up in several different new bacterial species in Australia and the United States, Peleg et al. (2004) and Limbago et al. (2011). Venturing Further into the Bacterial Maze—Creationist history lessons on religion & politics Parenthetically, the metallo-β-lactamase issue briefly elbows us into the Biblical antievolution world via Toleman et al. (2003), as microbiologist Mark Toleman happens to be a British creationist. His involvement didn’t preclude their collective employment of phylogenetic analysis to generate a cladogram of IMP relationships (suggesting how creationists can operate within an overall framework of evolutionary presumptions, at least while they don’t think too much about the implications of their own collaborative work). Venturing into the garden maze of Toleman’s non-evolutionary view of things affords an opportunity to explore those pesky bacteria from another direction. Apart from signing the Discovery Institute petition, his only declaration on the antievolution theme was Toleman (2003) framing the 18th century dispute over “spontaneous generation” biogenesis as one of sloppy pseudoscientific charlatans egged on by “godless peer pressure” until the superior skills of properly devout scientists confirmed the truth that only God could do Life. There were quite a few dramatis personae involved, but the primary figures were John Needham (1713-1781) on the spontaneous generation side and his resolute opponent Lazzaro Spallanzani (1729-1799). Toleman had drawn on only one main resource for this affair, the 1926 classic Microbe Hunters by microbiologist Paul de Kruif (1890-1971), which while an invigorating read (awash with imagined conversations and vivid scenic detail) offered a precariously dated popular science footing for what Toleman thought to do with the biogenesis story: kicking away abiogenesis experiments of the 21st century by proxy, work involving amino acids and lipid research not only unfamiliar to Spallanzani in the 18th century but to de Kruif in the Roaring Twenties. The historical scholarship of the Needham-Spallanzani dispute had also progressed since 1926 (the year after the Scopes Trial, remember), such as Hellman (1998, 63-79) and Capanna (1999) or the survey by Wilkins (2004) for the Talk.Origins Archive, but superficial documentation wasn’t Toleman’s only problem. Because his 21st century creationist world is a combat zone between godly design and materialist atheism, Toleman had to do some careful parsing of the religious convictions of the spontaneous generation protagonists, characterizing Needham as a "Catholic priest who liked to dabble in pseudoscience” while identifying Spallanzani as also “a Catholic priest but one that really believed in a God.” In this he had to climb over his own source, where the chapter on Spallanzani in de Kruif (1926, 23- 53) was already prone to breezy characterizations like “the Italian was a nasty fellow who liked to slaughter ideas of any kind that were contrary to his,” but de Kruif was particularly serpentine regarding Spallanzani’s faith: Despising secretly all authority, he got himself snugly into the good graces of powerful authorities, so that he might work undisturbed.

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