A new paper in Proceedings of the National Academy of Sciences USA has vindicated Michael Behe in one of the central controversies over his 2007 book The Edge of Evolution. Behe already reported here on the paper, which found that multiple mutations, at least two, are required to confer resistance to the drug chloroquine on malaria parasites:
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Behe's argument in
The Edge of Evolution didn't depend on whether chloroquine resistance arose in a stepwise manner, or only after multiple mutations accumulated. His argument was based upon an empirically observed data point from public health studies which found that chloroquine resistance arose in about 1 in every 1020 organisms.
He had a strong citation for this empirical observation: Nicholas White, "Antimalarial Drug Resistance," Journal of Clinical Investigation, Vol. 113: 1084-1092 (2004). He called the mutations (whatever they were) that caused chloroquine resistance a "chloroquine complexity cluster" or CCC. Whatever molecular mechanisms may be behind a CCC, empirical data showed that 10^20 cells are required in order to produce one. Behe pointed out that if a trait required the molecular equivalent of two CCC's before providing any advantage, then that would pose major problems for Darwinian evolution.
It's a simple calculation.
Behe observed that if 10^20 organisms were required to obtain one CCC, then the square of that amount -- 10^40 organisms -- would be required to evolve a trait that required two CCC's before providing any advantage. However, as Behe observed, a total of only 10^40 organisms have lived on Earth over the entire history of the planet.
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Will Ken Miller, Jerry Coyne, Paul Gross, Nick Matzke, Sean Carroll, Richard Dawkins, and PZ Myers Now Apologize to Michael Behe?
Behe's critics misread him as saying that a single CCC necessarily required multiple simultaneous mutations, and castigated Behe for allegedly ignoring the possibility of a single CCC arising via sequential mutations. For example:
• Kenneth Miller: "It would be difficult to imagine a more
breathtaking abuse of statistical genetics. 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." (Nature, 2007)
• Paul Gross: "Behe assumes simultaneous mutations at two sites in the relevant gene, but there is no such necessity and plenty of evidence that cumulativeness, rather than simultaneity, is the rule. As Nature's reviewer (Kenneth R. Miller) notes, 'It would be difficult to imagine a more
breathtaking abuse of statistical genetics.'" (The New Criterion, 2007)
• Jerry Coyne: "What has Behe now found to resurrect his campaign for ID?
It's rather pathetic, really. ... Behe requires all of the three or four mutations needed to create such an interaction to arise simultaneously. ... If it looks impossible, this is only because of Behe's
bizarre and unrealistic assumption that for a protein-protein interaction to evolve, all mutations must occur simultaneously, because the step-by-step path is not adaptive." (The New Republic, 2007)
• Nick Matzke: "Here is the
flabbergasting line of argument. First, Behe admits that CQR evolves naturally, but contends that it requires a highly improbable simultaneous double mutation, occurring in only 1 in 1020 parasites. ... The argument collapses at every step." (Trends In Ecology and Evolution, 2007)
• Sean Carroll: "Behe makes a new set of explicit claims about the limits of Darwinian evolution,
claims that are so poorly conceived and readily dispatched that he has unwittingly done his critics a great favor in stating them. ... Behe's main argument rests on the assertion that two or more simultaneous mutations are required for increases in biochemical complexity and that such changes are, except in rare circumstances, beyond the limit of evolution. .. Examples of cumulative selection changing multiple sites in evolving proteins include ... pyrimethamine resistance in malarial parasites -- a notable omission given Behe's extensive discussion of malarial drug resistance. ... [T]he argument for design has no scientific leg to stand on." (Science, 2007)
• Richard Dawkins: "
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. ... If correct, Behe's calculations would at a stroke confound generations of mathematical geneticists, who have repeatedly shown that evolutionary rates are not limited by mutation." (New York Times, 2007)
• And then of course there's PZ Myers. He made much the same criticisms, and also wrote:
Behe isn't just a crackpot who thinks he has a novel explanation for an evolutionary mechanism -- he's a radical anti-evolutionist extremist who rejects the entire notion of the transformation of species by natural processes. ... Most of the arguments are gussied up versions of the kind of handwaving, ignorant rationalizations you'd get from some pomaded fundagelical Baptist minister who got all his biology from the Bible, not at all what you'd expect from a tenured professor of biochemistry at a good university -- throwing in an occasional technical gloss or mangled anecdote from the literature is only a gloss to fool the rubes.