Richard Dawkins' <i>The Greatest Show on Earth</i> Shies Away from Intelligent Design but Unwittingly Vindicates Michael Behe - Evolution News & Views

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Richard Dawkins' The Greatest Show on Earth Shies Away from Intelligent Design but Unwittingly Vindicates Michael Behe

Richard Dawkins' new book, The Greatest Show on Earth, is being touted as a scathing rebuttal to intelligent design (ID), yet an actual response to mainstream ID thinking can hardly be found in the book. Though the book makes passing mention of "irreducible complexity" in a couple places, there are zero mentions of leading ID proponents like Michael Behe, William Dembski, Jonathan Wells, Phillip Johnson, Stephen Meyer, or any other well-known ID proponent. Instead, Dawkins refers extensively to "creationists," repeatedly attacking young earth creationism, while also making heavy use of fallacious (and dubious) "poor design" examples that rebut no argument made by a leading advocate of design since perhaps the 19th century. It seems that Dawkins didn't have the stomach to tackle the actual modern theory of intelligent design in his new book.

Dawkins Refutes Straw Men and Ignores ID Thinking on Evolutionary Research
The closest place Dawkins comes to actually dealing with actual ID is in Chapter 5 where he mentions irreducible complexity a couple times and discusses Richard Lenski's E. coli experiments. In typical Dawkins fashion, he taunts "creationists" with their alleged inability to respond to Lenski's research, which he claims they "hate":

There is a comic sequel to this triumphant tale of scientific endeavor. Creationists hate it. Not only does it show evolution in action; not only does it show new information entering enomes without the intervention of a designer, which is something they have all been told to deny is possible ('told to' because most of them don't understand what 'information' means); not only does it demonstrate the power of natural selection to put together combinations of genes that, by the naïve calculations so beloved of creationists, should be tantamount to impossible; it also undermines their central dogma of 'irreducible complexity.' So it is no wonder they are disconcerted by the Lenski research, and eager to find fault with it.

(Richard Dawkins, The Greatest Show on Earth, pg. 131 (Free Press, 2009).)

Were Dawkins not setting up a straw man, he might have then gone on to discuss Michael Behe's critique and evaluation of Lenski's work. After all, Behe is the leading proponent of irreducible complexity, and Behe has written quite a bit about Lenski's work, most notably in Behe's 2007 book, The Edge of Evolution.

But no. As we already saw, Behe's name appears nowhere in Dawkins' book. Instead, Dawkins slams Conservapedia editor Andrew Schalfly--whom Dawkins carefully notes is "a lawyer" (pgs. 131, emphasis in original)--who apparently made a misguided attempt to impugn Lenski by wrongly implying the scientist would not release his original data. It's a boring anecdote and a straw man, especially considering that a rebuttal to Behe is nowhere to be found in The Greatest Show on Earth.

Dawkins' Centerpiece Example of Biochemical Evolution Is Comfortably Within Behe's 'Edge of Evolution'

So what is it about Lenski's work that Dawkins claims is so devastating to irreducible complexity? Dawkins lauds 2 achievements of Lenski's experiments: (1) the ability of the bacteria to increase their size (there are no new genes here, just, as Dawkins admits, that they "had changed their levels of expression" of certain genes), and (2) the fact that Lenski's E. coli apparently evolved the ability to metabolize citrate. It's the latter example which Dawkins claims "undermines" the "central dogma of irreducible complexity."

Dawkins doesn't even offer a hint to his readers about this, but Behe dealt with this research from Lenski when it was first published back in 2008. Dawkins states that "if only a mutant could 'discover' how to deal with citrate, a bonanza would open up for it. This is exactly what happened..." (pg. 127) but according to Behe, that 'isn't exactly what happened':

Now, wild E. coli already has a number of enzymes that normally use citrate and can digest it (it's not some exotic chemical the bacterium has never seen before). However, the wild bacterium lacks an enzyme called a "citrate permease" which can transport citrate from outside the cell through the cell's membrane into its interior. So all the bacterium needed to do to use citrate was to find a way to get it into the cell. The rest of the machinery for its metabolism was already there. As Lenski put it, "The only known barrier to aerobic growth on citrate is its inability to transport citrate under oxic conditions." (1)

(Michael Behe, Amazon Blog, "Multiple Mutations Needed for E. Coli," June 6, 2008)

Dawkins somehow forgets to tell his readers the small detail that normal E. coli already has all the machinery to metabolize citrate, instead making this out to be some big evolutionary accomplishment. But Behe finds that this modest evolutionary research is completely within what he has all-along been saying is the "edge of evolution":
The major point Lenski emphasizes in the paper is the historical contingency of the new ability. It took trillions of cells and 30,000 generations to develop it, and only one of a dozen lines of cells did so. What's more, Lenski carefully went back to cells from the same line he had frozen away after evolving for fewer generations and showed that, for the most part, only cells that had evolved at least 20,000 generations could give rise to the citrate-using mutation. From this he deduced that a previous, lucky mutation had arisen in the one line, a mutation which was needed before a second mutation could give rise to the new ability. The other lines of cells hadn't acquired the first, necessary, lucky, "potentiating" (1) mutation, so they couldn't go on to develop the second mutation that allows citrate use. Lenski argues this supports the view of the late Steven Jay Gould that evolution is quirky and full of contingency. Chance mutations can push the path of evolution one way or another, and if the "tape of life" on earth were re-wound, it's very likely evolution would take a completely different path than it has.

I think the results fit a lot more easily into the viewpoint of The Edge of Evolution. One of the major points of the book was that if only one mutation is needed to confer some ability, then Darwinian evolution has little problem finding it. But if more than one is needed, the probability of getting all the right ones grows exponentially worse. "If two mutations have to occur before there is a net beneficial effect -- if an intermediate state is harmful, or less fit than the starting state -- then there is already a big evolutionary problem." (4) And what if more than two are needed? The task quickly gets out of reach of random mutation.

(Michael Behe, Amazon Blog, "Multiple Mutations Needed for E. Coli," June 6, 2008)

But the foil Dawkins chose for Lenski's research was not the informed Behe (who offered interesting commentary on Lenski's research over a year before Dawkins' book came out), but some misguided e-mail sent to Lenski by Schlafly. It's much easier for Dawkins to knock down a straw man. But Behe is exactly right: this research contradicts no ideas written about by ID proponents.

In fact, Behe has done a lot more than just write about this topic; he's published rigorous calculations and simulations in a peer-reviewed scientific journal, Protein Science (also totally ignored by Dawkins), showing that when more than two mutations are required to gain function, it's very difficult to evolve the trait under normal population sizes and generation times, etc. Their paper concludes:

The fact that very large population sizes--109 or greater--are required to build even a minimal [multi-residue] feature requiring two nucleotide alterations within 108 generations by the processes described in our model, and that enormous population sizes are required for more complex features or shorter times, seems to indicate that the mechanism of gene duplication and point mutation alone would be ineffective, at least for multicellular diploid species, because few multicellular species reach the required population sizes.

(Michael J. Behe & David W. Snoke, "Simulating Evolution by Gene Duplication of Protein Features That Require Multiple Amino Acid Residues," Protein Science, Vol 13:2651-2664 (2004).)

In 2008, Behe and Snoke's would-be critics in Genetics tried to refute Behe but found that to obtain only 2 necessary mutations via Darwinian evolution "for humans with a much smaller effective population size, this type of change would take > 100 million years." The critics admitted this was "very unlikely to occur on a reasonable timescale." In other words, there is too much complex and specified information in many proteins and enzymes in humans to be generated by Darwinian processes on reasonable evolutionary timescale. (Behe's responses to these critics are linked here.)

So where exactly is the 'edge of evolution'? Dawkins' readers won't find out because the examples Dawkins gives are comfortably within the edge offered by Behe before Lenski's E. coli and citrate research was even published. There's a fascinating scientific debate here going on here about the information generative ability of Darwinian evolution, and it's quite unfortunate that Dawkins hides this debate from his readers.

Perhaps Dawkins is right that creationists do indeed "hate" Lenski's research. I don't really know. But Behe, who is no creationist, clearly embraces Lenski's E. coli research because it validates his arguments about the limits of Darwinian evolution's ability to generate complex new functional biological features.

Dawkins Unwittingly Validates Behe
Dawkins probably was wise to avoid talking about Behe in The Greatest Show on Earth, because it turns out that some of Dawkins' arguments sound very much like Behe's arguments in The Edge of Evolution. First, let's review some comments from Behe in response to Lenski's citrate research:

In The Edge of Evolution I had argued that the extreme rarity of the development of chloroquine resistance in malaria was likely the result of the need for several mutations to occur before the trait appeared. Even though the evolutionary literature contains discussions of multiple mutations (5), Darwinian reviewers drew back in horror, acted as if I had blasphemed, and argued desperately that a series of single beneficial mutations certainly could do the trick. Now here we have Richard Lenski affirming that the evolution of some pretty simple cellular features likely requires multiple mutations.

(Michael Behe, Amazon Blog, "Multiple Mutations Needed for E. Coli," June 6, 2008)

Sounding very much like Behe, in The Greatest Show on Earth Dawkins also argues that the reason the citrate mutation was rare is because it probably required multiple mutations to arise--two mutations in fact. Dawkins thus writes:
What if the necessary biochemical wizardry to feed on citrate requires not just one mutation but two (or three)? We are not now talking about mutations that build on each other in a simple additive way. If we were, it would be enough to get the two mutations in any order. Either one, on its own, would take you halfway (say) to the goal; and either on its own would confer an ability to get some nourishment from citrate, but not as much as both mutations together would. That would be on a par with the mutations we have already discussed for increasing body size. But such a circumstance would not be rare enough to account for the dramatic uniqueness of Tribe Ara-3. No, the rarity of citrate metabolism suggests that we are looking for something more like the 'irreducible complexity' of creationist propaganda. This might be a biochemical pathway in which the product of one chemical reaction feeds into a second chemical reaction, and neither can make any inroads at all without the other. This would require two mutations, call them A and B, to catalyze the two reactions. On this hypothesis, you really would need both mutations before there is any improvement whatsoever, and that would really be improbable enough to account for the observed result that only one out of the twelve tribes achieved the feat."

(Richard Dawkins, The Greatest Show on Earth, pg. 129 (Free Press, 2009), emphasis in original.)

There are some remarkable points that can be drawn out of this paragraph from Dawkins, not the least of which is that it validates one of Behe's central arguments in The Edge of Evolution.

First, both Behe and Dawkins agree that logically speaking, the extreme rarity of a trait might be taken as evidence that multiple sequential mutations are necessary before the trait arises and an advantage is gained. As Behe notes in the quote above, this was his central logic showing that the evolution of malarial resistance to chloroquine required multiple mutations before resistance could occur.

Yet Behe was skewered by reviewers for using this same allegedly mistaken logic; they accused him of ignoring the possibility of stepwise mutations. Thus, in their reviews of The Edge of Evolution, Ken Miller, Jerry Coyne, and Paul Gross each challenged Behe's claim that the rarity of chloroquine resistance implies multiple mutations are necessary for it to occur. All three biologists alleged that Behe failed to recognize that such resistance can evolve in a stepwise fashion. All three biologists missed Behe's point.

The rarity of chloroquine resistance is not in question. In fact, Behe's statistic that it occurs only once in every 1020 cases was derived from public health statistical data, published by an authority in the Journal of Clinical Investigation. The extreme rareness of chloroquine resistance is not a negotiable data point; it is an observed fact.

According to Behe's (and Dawkins') logic, extreme rarity of a trait can imply it requires multiple mutations to arise; if there were a simple evolutionary pathway, resistance would not be so rare. Dawkins uses precisely the same logic, arguing that its rarity implies that multiple mutations are required, writing, "No, the rarity of citrate metabolism suggests that we are looking for something more like the 'irreducible complexity' of creationist propaganda. This might be a biochemical pathway in which the product of one chemical reaction feeds into a second chemical reaction, and neither can make any inroads at all without the other. This would require two mutations, call them A and B, to catalyze the two reactions." (pg. 129)

Yet consider how Gross, Miller, and Coyne skewered Behe for similarly arguing that the rarity of trait implies that perhaps more than one mutation is required for the trait:

Gross: "Second, 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)

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)

Coyne: "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)
So did Behe ignore the possibility of evolution by stepwise mutations, each of which confers a selective advantage? Not at all. In fact, in The Edge of Evoluton Behe makes it quite clear that evolution works best when stepwise mutations, each of which gives an advantage, are possible:
First, steps. The more intermediate evolutionary steps that must be climbed to achieve some biological goal without reaping a net benefit, the more unlikely a Darwinian explanation. ...

... The eminent evolutionary biologist John Maynard Smith, who died in 2004, addressed this point over thirty years ago and reached an important conclusion:

The model of protein evolution I want to discuss is best understood by analogy with a popular word game. The object of the game is to pass from one word to another of the same length by changing one letter at a time, with the requirement that all the intermediate words are meaningful in the same language. Thus WORD can be converted into GENE in the minimum number of steps as follows: WORD WORE GORE GONE GENE
Because mutations are relatively rare, the monkey's typing is almost always judged after a single keystroke. Bad changes are quickly eliminated. So, reasoned Smith, evolution has to slog along one tiny beneficial step at a time. If it needs two changes to help, it gets stuck. University of Rochester evolutionary biologist H. Allen Orr recently seconded John Maynard Smith's reasoning:
Given realistically low mutation rates, double mutants will be so rare that adaptation is essentially constrained to surveying--and substituting--one-mutational step neighbors. Thus if a double-mutant sequence is favorable but all single amino acid mutants are deleterious, adaptation will generally not proceed.
If two mutations have to occur before there is a net beneficial effect--if an intermediate state is harmful, or less fit than the starting state--then there is already a big evolutionary problem....

...Random mutation is the perfect tool for the evolutionary job when steps are continuous and close together. When there are some broken stairs, with small gaps between steps, it's a potential tool. ...

...The Darwinian magic works well only when intermediate steps are each better ('more fit') than preceding steps, so that the mutant gene increases in number in the population as natural selection favors the offspring of people who have it.

(Michael Behe The Edge of Evolution pp. 104-108, 112 (Free Press, 2007).)

Behe acknowledges that evolution can readily proceed when only one mutation is required to get some stepwise advantage (in such a case, Behe even says that random mutation is the "perfect tool"). Contra Gross, Coyne, and Miller, Behe in no way ignores or dismisses the possibility of stepwise evolution.

So how does Behe infer that multiple mutations were necessary to gain any advantage? It's based upon the observed extreme rarity of the trait. Yet this is the precise reverse-engineering type of logic used by Dawkins to make the exact same inference with regards to Lenski's citrate evolution.

Somehow, something tells me that no one is going to skewer Dawkins for using this same logic--valid logic--as Behe.

But there is one other point, even more profound to be made here...

Fin
In closing, step back consider what's going on here. Dawkins' centerpiece evidence for biochemical evolution to "undermine" irreducible complexity is Lenski's research on citrate on E. coli. But as Behe argues, this is a modest accomplishment, well within the edge of evolution. If Lenski's results are about the best we've seen evolution do, then there's no reason to believe evolution could produce many of the complex biological features we see in the cell. As Behe concludes his rebuttal to Lenski's citrate research: "If the development of many of the features of the cell required multiple mutations during the course of evolution, then the cell is beyond Darwinian explanation. I show in The Edge of Evolution that it is very reasonable to conclude they did."