11 August 2008

Why I'm not a Behe fan, Part IIA: the malaria scam

In my previous post, I started to explain a fact that some people (who don't know me) seem to find surprising or noteworthy. Michael Behe is a Christian who accepts common ancestry and an ancient cosmos, so you'd think I would be excited about the work of a fellow "theistic evolutionist." But I'm not. Two overall problems come to mind. (Basically, I find his conduct as a scientist to be unacceptable, and I find his proposals to be laughable failures.) I'm addressing the second one here. The discussion is quite long, so I'm dividing it into two parts, A and B.

1. Behe's fans say that he's a nice guy, and that the evolutionists are "crucifying" him. Both claims seem to be true, but they can't hide some serious problems with his conduct as a scientist. First, he showed contempt for his (former) colleagues when he avoided the process of peer review. Second, his comment-free blog is lamentably characterized by misleading and disingenuous "responses" to criticism that look to be calculated attempts to protect what is nothing more than folk science.

Those issues are the subject of the first post.

2. Some of Behe's defenders think that he has effectively answered his critics. He has not, nor has he understood or acknowledged the most important criticisms of his crude claims.

There's something interesting about the ID community's response to Jerry Coyne's review of The Edge of Evolution (henceforth EoE). Thomas Cudworth referred to it as "nasty" and Behe dismissed it as just so much ad hominem and "question-begging." Meanwhile, Bilbo (regular commenter here and contributor at Telic Thoughts) thinks that Behe is "carrying the day" on his comment-free Amazon blog.com, where he has responded to critiques by Ken Miller, Richard Dawkins, Sean Carroll and others.

Well, in fact the review is a piece of crap, as is much of what Jerry Coyne has produced lately. (He's an equal opportunity thug, attacking his scientific colleagues with the same lack of grace and intelligence that he displayed in his recent diatribe against faith.) The piece represents at best a missed opportunity (to address Behe's claims in detail for a lay audience) and at worst a windfall for Behe and the ID movement, focused as they are on convincing the public that they are a persecuted scholarly minority. I'm not the only one who was horrified by Coyne's brainless screed; Jason Rosenhouse blasted it for all the same reasons.

As Rosenhouse predicted, the shoddy nature of Coyne's review enabled Behe to avoid a full-scale defense of his folk science. Behe has never bothered to rigorously justify his claims, and has never carefully engaged existing evolutionary data or theory, so Coyne's shallow account gave him a perfect opportunity to continue to pretend that his ideas can withstand real scientific scrutiny. And so we have ID propagandists whining about Behe's mistreatment, and laypersons reading ID blogs and concluding that EoE has sounded an unanswered challenge to evolutionary theory. It's a boon for ID.

The truth is that Jerry Coyne did identify the errors in the book. EoE makes exactly one specific scientific claim, accompanied by simplistic genetic assumptions and supported by a "case study." The scientific claim is that the mutations that drive large-scale evolution, and that are thought to underlie all evolutionary change (past and present), are non-random. And the "case study" is a long-winded account of the adaptation of the malaria parasite in the face of drugs intended for its destruction. Coyne's review addresses both, and Behe's responses failed to defend either.

The scientific claim is unsupported, and all available evidence contradicts it. And the "case study" is laughably misused in a ploy that a high school sophomore could see through. Let's look at the malaria ploy first, then examine Behe's central scientific claim and its implications in the second half of this article (part B, to be posted later this week).

EoE is actually a very small book, with very little to say. Most of the book is devoted to a recounting of the biology of the malaria parasite, Plasmodium falciparum, and the "trench warfare" between the parasite and its host, Homo sapiens. The outcome of the struggle between the parasite and its host has provided a useful case study of evolutionary change, and specifically of the power of natural selection. Behe grants this readily; indeed, he concludes that random mutation and natural selection can account for the divergence of organisms at the species level (at least). In other words, Behe does not deny the reality of common descent, and acknowledges some role in evolution for natural selection acting on random mutation. (He uses the divergence of dog breeds as an example of what random mutation & selection can do (p. 200), leaving one to wonder why Richard Dawkins chose dogs as an example of why Behe is wrong. I'm guessing Dawkins didn't read the book too carefully, what with all his important work as a scholar.) But Behe's reasoning is stunningly dumb. It goes like this.

  • In the fifty years since antimalarial drugs were brought to bear on P. falciparum, more than 1020 (that's 10 to the 20th power, if the superscript isn't working) of the parasites have been born.
  • In that time, the parasite has adapted to the drugs, through selection acting on random genetic variation, but hasn't developed any completely new proteins or biochemical functions.
  • This means that the Darwinian process is unable to generate significant novelty in fewer than 1020 tries.
That's the argument. And Behe uses it to identify the "edge of evolution."

Now, I hope it's already clear to most readers why the argument is spectacularly bad, but here are some comments.
  • Most basically, it should be obvious that demonstrating the failure of X to happen in one particular situation is hardly proof that X cannot happen. To extrapolate from a single negative observation (even if it were representative of the scenario in question) to the blanket impossibility of the phenomenon is a foolish mistake.
  • More specifically, it should be obvious that we need not expect dramatic new functions to appear during adaptation, since we need not even expect adaptation to occur at all. If functional innovation were as inevitable as adaptation, the dinosaurs would not merely have survived, they would have mastered apparation in additional to intergalactic travel (and world peace). Behe wants you to believe that evolutionary biologists expect dramatic evolutionary innovation to occur, at the level of molecular machinery, whenever selection is applied to a population. That's nonsense, and I think he must know that.
  • It is important to keep in mind that Behe solidly affirms common ancestry, and knows that mutations account for the differences between lineages. This means that he acknowledges the existence of a continuous genetic tree of life, which means that he should be able to formulate scientifically credible approaches to his hypothesis. Pointing to the lack of innovation in one special (parasitic) scenario is hardly a substitute for a direct examination of the myriad exemplars of evolutionary novelty. In other words, the way to determine whether gigantic population sizes are needed for the stepwise generation of novel functions via random mutation is to: a) identify examples of such evolutionary innovations and to work on elucidating the genetic trajectories that could have led to their development; then b) work on determining the population sizes, mutation frequencies, and other parameters that apply to the trajectory. (I like to call this "science.")
The questions that I have after reading EoE (besides the disturbing question raised also by Dennis in a comment here) are these: does Mike Behe really think that evolutionary biologists expect P. falciparum to develop new molecular machines while adapting to antimalarial drug assault? Does he really think that the struggle between a primate and one of its parasites is a model for the generation of evolutionary novelty, of whole gene families whose origins often predate the Cambrian? Does he really believe that the failure of P. falciparum to give rise to a magic drug-dodging charm, or a microscopic invisibility cloak, is an argument against random mutation and natural selection in the evolution of biological novelty?

Probably not. He has another really bad idea: that random mutation doesn't provide enough variation for natural selection to generate novelty. And the mistakes are typical for him: sloppy (or non-existent) examination of the facts, and wild extrapolation from those he carefully selects. Part IIB will look at the rest of the mess.

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