Print Blog Article

Distinguished UC Berkeley Paleontologist Reviews Meyer's Book "Darwin's Doubt" (a book too important to ignore)

Wed, Oct. 02, 2013 Posted: 10:04 PM

UC Berkeley paleontologist Charles Marshall's review of Stephen Meyer's book Darwin's Doubt: The Explosive Origin of Animal Life and the Case for Intelligent Design represents a significant turn of events. Finally, about three months after the publication Meyer's book, a reputable Darwinist actually addresses the main evidence and arguments in Meyer's case for ID from the Cambrian explosion. This review unwittingly demonstrates that Meyer's book raises questions that the evolutionary establishment can't simply ignore. This is precisely, at minimum, what Meyer had hoped to accomplish. Congratulations to my colleague Stephen Meyer and to his worthy debate partner, the distinguished Charles Marshall.

Meyer observed yesterday:

Though Marshall does address the main problem discussed in the book, his review also demonstrates -- if inadvertently -- the severity of that problem, and that leading Cambrian paleontologists and evolutionary biologists (such as Dr. Marshall) are nowhere close to solving it.

Meyer will be releasing a series of detailed responses to the main critiques in Marshall's review in the days to follow. Meanwhile, his initial response starts with this (go here for the original with footnotes, emphasis and explanatory notes in brackets below are mine):

I begin here by addressing Marshall’s claim that developmental gene regulatory networks (dGRNs), which are necessary for the development of animals, could have been more ... flexible in the past. Marshall made this claim to challenge my contention in Chapter 13 of Darwin’s Doubt that the observed inflexibility of these regulatory networks represents a major impediment to the evolutionary transformation of one animal body plan into another. Not so, he argues. As he asserted in his review, “today's GRNs have been overlain with half a billion years of evolutionary innovation (which accounts for their resistance to modification), whereas GRNs at the time of the emergence of the phyla were not so encumbered."

Yet, contrary to Marshall’s speculation about how dGRNs might have functioned in the past, all available observational evidence establishes that dGRNs do not tolerate random perturbations to their basic control logic. Indeed, mutagenesis experiments conducted on the genes present in dGRNs have repeatedly shown that even modest mutation-induced changes to these genes either produce no change in the developmental trajectory of animals (due to pre-programmed buffering or redundancy) or they produce catastrophic (most often, lethal) effects within developing animals. Disrupt the central control nodes, and the developing animal does not shift to a different, viable, stably heritable body plan. Rather, the system crashes, and the developing animal usually dies. As developmental biologist Eric Davidson [who is an evolutionary theorist and not an ID advocate] has noted:

There is always an observable consequence if a dGRN subcircuit is interrupted. Since these consequences are always catastrophically bad, flexibility is minimal, and since the subcircuits are all interconnected, the whole network partakes of the quality that there is only one way for things to work. And indeed the embryos of each species develop in only one way.

Thus, to claim, as Marshall does in his review of Darwin’s Doubt, that dGRNs might have been more elastic in the past contradicts what developmental biologists have learned over several decades investigating how these networks actually function from mutagenesis studies of many different biological "model systems," including Drosophila (fruit flies), Caenorhabditis (nematodes), Strongylocentrotus (sea urchins), Danio (zebrafish) and other animals. Moreover, as Marshall himself has noted elsewhere, there is a good reason for this inflexibility. As Marshall explains, “many of the characters that evolved during the origin of the phyla are no longer able to change. The reason for this is that selectable variation is absent: either the characters are invariant or mutants that carry this variation are sterile or lethal.”

Of course, Marshall thinks that these networks could have had a different, more flexible, character in the past. Yet, given what dGRNs do, namely, that they enable different cell types to organize themselves, and differentiate themselves from each other, in precise ways at precise times during the development of specific animal forms, it is hard see how dGRNs could have functioned as regulatory networks and also exhibited the kind of flexibility that Marshall envisions. Developmental gene regulatory networks are control systems. A labile [significantly variable] dGRN would generate (uncontrolled) variable outputs, precisely the opposite of what a functional control system does. It is telling that although many evolutionary theorists (like Marshall) have speculated about early labile dGRNs, no one has ever described such a network in any functional detail -- and for good reason. No developing animal that biologists have observed exhibits the kind of labile [significantly variable] developmental gene regulatory network that the evolution of new body plans requires. Indeed, Eric Davidson, when discussing hypothetical labile dGRNs, acknowledges that we are speculating "where no modern dGRN provides a model" since they "must have differed in fundamental respects from those now being unraveled in our laboratories."

Don't miss the jolting disconnect between Marshall's speculation and our vast knowledge of developmental biology: No developing animal embryo that we have observed has the kind of significantly variable developmental gene regulatory network (dGRN) that the evolution of new body plans requires. Those, like Marshall, who speculate about significantly variable dGRNs are offering an argument from ignorance. The most reasonable conclusion, based on what we now know about dGRNs, indicates that these functional control systems are designed to direct embryological development with a very tight level of control in order to maintain the functional integrity of each animal embryo.

Based upon our vast and repeated experience of highly sophisticated control systems (e.g., in the world of computer technology), the origin of such information processing systems always traces back to a designing intelligence. This is an argument based on what we know, rather than what we don't know (such as Marshall's speculations). The ID infographic I posted last time illustrates the logic of the design inference (as an argument based on knowledge, rather than ignorance).

Meyer concludes (emphasis mine):

By ignoring this evidence, Marshall and other defenders of evolutionary theory reverse the epistemological priority of the historical scientific method as pioneered by Charles Lyell, Charles Darwin and others. Rather than treating our present experimentally based knowledge as the key to evaluating the plausibility of theories about the past, Marshall uses an evolutionary assumption about what must have happened in the past (transmutation) to justify disregarding experimental observations of what does, and does not, occur in biological systems. The requirements of evolutionary doctrine thus trump our observations about how nature and living organisms actually behave. What we know best from observation takes a back seat to prior beliefs about how life must have arisen.

Charles Marshall's review of Meyer's book is entitled "When Prior Belief Trumps Scholarship" and it is published in the prestigious journal Science (September 20, 2013). Did you catch the irony? Although Marshall accuses of Meyer of letting prior belief distort scholarship, there is a much better case for Marshall's prior Darwinian beliefs trumping decades of scholarship in developmental biology.

Although this is not a promising start for Marshall's critique of Meyer's case for ID, we should remind ourselves that Marshall's book review is a step of progress. Previous hostile reviews of Meyer's book exhibit a consistent evasiveness as to what Meyer's book actually argues. David Klinghoffer offers the following helpful Taxonomy of Evasion of previous Darwinian reviews of Meyer's book:

1. The Review Based on Undisguised Ignorance

It started months before publication of Darwin's Doubt, when of course no one had read the book, with Jerry Coyne (University of Chicago) and Joe Felsenstein (University of Washington) reassuring blog readers that they already pretty much knew what Meyer's arguments would be. Coyne's classic summary of Meyer's book: "Yes, baby Jesus made the phyla!"

2. The Review Based on Disguised Ignorance

Nick Matztke (UC Berkeley) supposedly read and reviewed Darwin's Doubt, in a post of more than 9,400 words published at Panda's Thumb less than 24 hours after he purchased the book on the date of its publication. The suspicion that Matzke failed to give Meyer's book a fair examination, the kind where you read the words on the pages rather than just flipping through and looking for your name in the index, is supported by the fact that he ignored its most important arguments. This didn't stop other writers (Jerry Coyne, Gareth Cook in The New Yorker, John Farrell in National Review) from citing Matzke as the authoritative source of their dismissals.

Meyer's previous book, Signature in the Cell, received much the same treatment, notoriously from Francisco Ayala (UC Irvine) who has given his name to this procedure. To "Ayala" a book is to read and pan it without having read the work.

3. The Reviewer Who Cannot Remember That His Objections Have Already Been Answered

Donald Prothero (Natural History Museum of Los Angeles County) is the holotype specimen here, though Nick Matzke falls into the category as well. See "Among Darwin Defenders, Evidence of Short-Term Memory Loss."

4. The Reviewer Who Cannot Remember That Previous Reviews of Darwin's Doubt Have Already Been Answered

John Pieret is only a blogger as far as I can tell, not a scholar in any field. He received congratulations for rounding up hostile reviews of Darwin's Doubt -- without anywhere acknowledging that we have been assiduously demolishing them pretty much as they appear. Again, it's like these guys experience a kind of memory reset when they come across information they don't like, as if they can't retain displeasing data so that it is sloughed off almost as soon as it is encountered. [use the link below to access all of Klinghoffer's Taxonomy of Evasion weblinks]

Read about the last two categories of evasion in David Klinghoffer's essay. We are not making this stuff up. This is not a practical joke. The previous reviews of Meyer's book have really been this bad. Congratulations to Charles Marshall for being the first serious scholar to actually respond to Meyer's main arguments. I will post more on the Marshall-Meyer dialogue in weeks to come.

Mike Keas