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Over at The Skeptical Zone, Mikkel “Rumraket” Rasmussen has written a post critical of Dr. Stephen Meyer, titled, Beating a dead horse (Darwin’s Doubt), which is basically a rehash of comments he made on a thread on Larry Moran’s Sandwalk blog last year. The author’s aim is to expose Dr. Stephen Meyer’s “extremely shoddy scholarship,” but as we’ll see, Rasmussen’s own research skills leave a lot to be desired.
Did Dr. Meyer fail to document his sources?
Rasmussen focuses his attack on chapter 10 of Dr. Meyer’s book, “Darwin’s Doubt.” He writes:
Having read the book, a recurring phenomenon is that Meyer time and again makes claims without providing any references for them. Take for instance the claim that the Cambrian explosion requires lots of new protein folds, from Chapter 10 The Origin of Genes and Proteins:
(Rasmussen proceeds to quote from Meyer’s book, on which he comments below – VJT.)
In the whole section Meyer dedicates to the origin of novel folds, he makes zero references that actually substantiate [his assertion] that the [C]ambrian diversification, or indeed any kind of speciation, or the [appearance of] new cells types or organs, require[d] new protein folds. ZERO. Not one single reference that supports these claims. At first it reads like what I quote[d] above, lots of claims, no references. Later on he eventually cites the work of Douglas Axe that atte[m]pts to address how hard it is to evolve new folds (and that work has its own set of problems, but never mind that). Axe makes the same claim in his ID-journal Bio-complexity papers (which eventually Meyers cites), but in Axe’s papers, that claim is not supported by any reference either. It’s simply asserted as fact. In other words, Meyer makes a claim, then cites Axe making the same claim. Neither of them give a reference.
(N.B. For ease of readability, I have used square brackets to correct Rasmussen’s spelling and punctuation errors, and I have also inserted four extra words, without which his meaning would have been obscure to readers, in the preceding paragraph – VJT.)
Rasmussen repeats his accusation that Dr. Meyer frequently makes claims in his book without providing any references for them, at the very end of his post:
Later Meyer gets a ID-complexitygasm when he asserts, again without any support, that:
“The Cambrian animals exhibit structures that would have required many new types of cells, each requiring many novel proteins to perform their specialized functions. But new cell types require not just one or two new proteins, but coordinated systems of proteins to perform their distinctive cellular functions.”
Where does he get this? His ass, that’s where.
Do new cell types require new kinds of proteins?
I find it quite astonishing that Rasmussen would require documentation for Dr. Meyer’s claim that new cell types would require new types of proteins, for three reasons. First, it’s a well-known fact that each different cell type has different cluster of differentiation proteins. Bojidar Kojouharov, a Ph.D. Student in Cancer Immunology, describes these proteins as follows:
Clusters of Differentiation (CD) are cell surface proteins used to differentiate one cell type from another. Each CD marker is a different surface protein from the others. As such, it will likely have different functions and may be expressed on different cells. Technically, different CD markers don’t really have to have anything in common, other than the fact that they are on the cell’s surface. Usually, it’s safe to assume any Clusters of Differentiation is a protein.
Second, it is widely admitted by authors in the field that the complex organisms which appeared in the Cambrian would have required a host of new cell types. Here, for instance, is what P. V. Sukumaran, of the Geological Society of India, says in his paper, Cambrian Explosion of Life: the Big Bang in Metazoan Evolution (RESONANCE, September 2004, pp. 38-50):
Yet another feature of the Cambrian explosion is the quantum jump in biological complexity. The early Cambrian animals had roughly 50 cell types while the sponges that appeared a little earlier had only 5… (p. 44, sidebar)
Unicellular life is relatively simple; there is little division of labour and the single cell performs all functions of life. Obviously the genetic information content of unicellular organisms is relatively meagre. Multicellular life, on the other hand, requires more genetic information to carry out myriads of cellular functions as their cells are differentiated into different cell types, tissues and organs. But new cell types themselves require specialised proteins, and novel proteins arise from novel gene sequences, that is new genetic information. As the organisms that appeared in the Cambrian explosion had many more novel and specialised cell types than their prokaryotic ancestors, the amount of new genetic information that arose in the Cambrian explosion represents a large increase in biological information. (p. 47)
Third, it turns out that Dr. Meyer provided the very references that Rasmussen chides him for failing to supply, over 14 years ago, in his 2001 paper, The Cambrian Explosion: Biology’s Big Bang, which he co-authored with Paul Nelson and Paul Chien, which is listed on page 471 of the bibliography of Dr. Meyer’s book, Darwin’s Doubt. (Actually, the bibliography cites a later and slightly more polished 2003 version of the same paper.) Allow me to quote from pages 32-33 of the 2001 paper (emphases mine – VJT):
As noted, the new animals of the Cambrian explosion would have required many new cell types and, with them, many new types of proteins acting in close coordination. It follows, therefore, that if the neo-Darwinian mechanism cannot explain the origin of new cell types (and the systems of proteins they require), it cannot explain the origin of the Cambrian animals. Yet given the number of novel proteins required by even the most basic evolutionary transformations, this now seems to be precisely the case.
Consider, for example, the transition from a prokaryotic cell to a eukaryotic cell. This transition would have produced the first appearance of a novel cell type in the history of life. Compared to prokaryotes, eukaryotes have a more complex structure including a nucleus, a nuclear membrane, organelles (such as mitocondria, the endoplasmic recticulum, and the golgi apparatus), a complex cytoskeloton (with microtubulues, actin microfilaments117 and intermediate filaments) and motor molecules.118 Each of these features requires new proteins to build or service, and thus, as a consequence, more genetic information. (For example, the spooled chromosome in a modern eukaryotic yeast [Saccharomyces] cell has about 12.5 million base pairs, compared to about 580,000 base pairs in the prokaryote Mycoplasma.)119 The need for more genetic information in eukaryotic cells in turn requires a more efficient means of storing genetic information. Thus, unlike prokaryotic cells which store their genetic information on relatively simple circular chromosomes, the much more complex eukaryotic cells store information via a sophisticated spooling mechanism.120 Yet this single requirement — the need for a more efficient means of storing information — necessitates a host of other functional changes each of which requires new specialized proteins (and yet more genetic information) to maintain the integrity of the eukaryotic cellular system.
For example, nucleosome spooling requires a complex of specialized histones proteins (with multiple recognition and initiation factors) to form the spool around which the double stranded DNA can wind.121 Spooled eukaryotic DNA in turn uses “intron spacers,” (dedicated sections of non-coding DNA), in part to ensure a tight electrostatic fit between the nucleosome spool and the cords of DNA.122 This different means of storing DNA in turn requires a new type of DNA polymerase to help access, “read,” and copy genetic information during DNA replication. (Indeed, recent sequence comparisons show that prokaryotic and eukaryotic polymerases exhibit stark differences).123 Further, eukaryotes also require a different type of RNA polymerase to facilitate transcription. They also require a massive complex of five jointly necessary enzymes to facilitate recognition of the promoter sequence on the spooled DNA molecule.124 The presence of intron spacers in turn requires editing enzymes (including endonucleases, exonucleases and splicesomes) to remove the non-coding sections of the genetic text and to reconnect coding regions during gene expression.125 Spooling also requires a special method of capping or extending the end of the DNA text in order to prevent degradation of the text on linear (non-circular) eukaryotic chromosomes.126 The system used by eukaryotes to accomplish this end also requires a complex and uniquely specialized enzyme called a telomerase.127
Thus, one of the “simplest” evolutionary transitions, that from one type of single-celled organism to another, requires the origin of many tens of specialized novel proteins, many of which (such as the polymerases) alone represent massively complex, and improbably specified molecules.128 Moreover, many, if not most, of these novel proteins play functionally necessary roles in the eukaryotic system as a whole. Without specialized polymerases cell division and protein synthesis will shut down. Yet polymerases have many protein subunits containing many thousands of precisely sequenced amino acids. Without editing enzymes, the cell would produce many nonfunctional polypeptides, wasting vital ATP energy and clogging the tight spaces within the cytoplasm with many large useless molecules. Without tubulin and actin the eukaryotic cytoskeloton would collapse (or would never have formed). Indeed, without the cytoskeleton the eukaryotic cell can not maintain its shape, divide, or transport vital materials (such as enzymes, nutrients, signal molecules, or structural proteins).129 Without telomerases the genetic text on a linear spooled chromosome would degrade, again, preventing accurate DNA replication and eventually causing the parent cell to die.130
Even a rudimentary analysis of eukaryotic cells suggests the need for, not just one, but many novel proteins acting in close coordination to maintain (or establish) the functional integrity of the eukaryotic system. Indeed, the most basic structural changes necessary to a eukaryotic cell produce a kind of cascade of functional necessity entailing many other innovations of design, each of which necessitates specialized proteins. Yet the functional integration of the proteins parts in the eukaryotic cell poses a severe set of probabilistic obstacles to the neo-Darwinian mechanism, since the suite of proteins necessary to eukaryotic function must, by definition, arise before natural selection can act to select them.
References:
117 Russell F. Doolittle, “The Origins and Evolution of Eukaryotic Proteins,” Philosophical Transactions of the Royal Society of London B 349 (1995): 235-40.
118 Stephen L. Wolfe, Molecular and Cellular Biology (Belmont, CA: Wadsworth, 1993), pp. 3, 6-19.
119 Rebecca A. Clayton, Owen White, Karen A. Ketchum, and J. Craig Ventner, “The First Genome from the Third Domain of Life,” Nature 387 (1997): 4459-62.
120 Stephen L. Wolfe, Molecular and Cellular Biology, pp. 546-50.
121 Ibid.
122 H. Lodish, D. Baltimore, et. al., Molecular Cell Biology (New York: W.H. Freeman, 1994), pp. 347-48. Stephen L. Wolfe, Molecular and Cellular Biology, pp. 546-47.
123 Edgell and Russell Doolittle, “Archaebacterial genomics: the complete genome sequence of Methanococcus jannaschii,” BioEssays 19 (no. 1, 1997): 1-4. Michael Y. Galperin, D. Roland Walker, and Eugene V. Coonin, “Analogous Enzymes: Independent Inventions in Enzyme Evolution,” Genome Research 8 (1998): 779-90.
124 Stephen L. Wolfe, Molecular and Cellular Biology, pp. 580-81, 597.
125 Ibid., pp. 581-82, 598-600, 894-96.
126 Ibid., p. 975.
127 Ibid., pp. 955-975.
128 Ibid., p. 580.
129 Ibid., pp. 17-19.
130 Ibid., pp. 955-975.
And here’s a highly pertinent quote from pages 5-6 of the paper:
Each new cell type requires many new and specialized proteins. New proteins in turn require new genetic information encoded in DNA. Thus, an increase in the number of cell types implies (at a minimum) a considerable increase in the amount of specified genetic information. For example, molecular biologists have recently estimated that a minimally complex cell would require between 318 to 562 kilobase pairs of DNA to produce the proteins necessary to maintain life.20 Yet to build the proteins necessary to sustain a complex arthropod such as a trilobite would require an amount of DNA greater by several orders of magnitude (e.g., the genome size of the worm Caenorhabditis elegans is approximately 97 million base pairs21 while that of the fly Drosophila melanogaster (an arthropod), is approximately 120 million base pairs.22 For this reason, transitions from a single cell to colonies of cells to complex animals represent significant (and in principle measurable) increases in complexity and information content. Even C. elegans, a tiny worm about one millimeter long, comprises several highly specialized cells organized into unique tissues and organs with functions as diverse as gathering, processing and digesting food, eliminating waste, external protection, internal absorption and integration, circulation of fluids, perception, locomotion and reproduction. The functions corresponding to these specialized cells in turn require many specialized proteins, genes and cellular regulatory systems, representing an enormous increase in specified biological complexity. Figure 5 shows the complexity increase involved as one moves upward from cellular grade to tissue grade to organ grade life forms. Note the jump in complexity required to build complex Cambrian animals starting from, say, sponges in the late Precambrian. As Figure 5 shows Cambrian animals required 50 or more different cell types to function, whereas sponges required only 5 cell types.
(Note: Figure 5 can be viewed in this later version of the paper, where it is labeled as Figure 10 – VJT.)
References:
20 Mitsuhiro Itaya, “An estimation of the minimal genome size required for life,” FEBS Letters 362
(1995): 257-60. Claire Fraser, Jeannine D. Gocayne, Owen White, et. al., “The Minimal Gene Complement of Mycoplasma genitalium,” Science 270 (1995): 397-403. Arcady R. Mushegian and Eugene V. Koonin, “A minimal gene set for cellular life derived by comparison of complete bacterial genomes,” Proceedings of the National Academy of Sciences USA 93 (1996): 10268-73.
21 The C. elegans Sequencing Consortium, “Genome Sequence of the Nematode C. elegans: A Platform for Investigating Biology,” Science 282 (1998): 2012-18.
22 John Gerhart and Marc Kirschner, Cells, Embryos, and Evolution (London: Blackwell Science, 1997), p.
121
Did Dr. Meyer distort the words of geneticist Susumu Ohno?
Rasmussen also accuses Dr. Meyer of distorting the words of Susumu Ohno, a geneticist and evolutionary biologist whose work he discussed in chapter 10 of his book, Darwin’s Doubt:
It gets much worse, turns out Meyer is making assertions diametrically opposite to what his very very few references say. Remember what Meyer wrote above?
“The late geneticist and evolutionary biologist Susumu Ohno noted that Cambrian animals required complex new proteins such as, for example, lysyl oxidase in order to support their stout body structures.”
Well, much later in the same chapter, Meyer finally references Ohno:
“Third, building new animal forms requires generating far more than just one protein of modest length. New Cambrian animals would have required proteins much longer than 150 amino acids to perform necessary, specialized functions.21”
What is reference 21? It’s “21. Ohno, “The Notion of the Cambrian Pananimalia Genome.””
What does that reference say? Let’s look:
“Reasons for Invoking the Presence of the Cambrian Pananimalia Genome.
Assuming the spontaneous mutation rate to be generous 10^-9 per base pair per year and also assuming no negative interference by natural selection, it still takes 10 million years to undergo 1% change in DNA base sequences. It follows that 6-10 million years in the evolutionary time scale is but a blink of an eye. The Cambrian explosion denoting the almost simultaneous emergence of nearly all the extant phyla of the kingdom Animalia within the time span of 6-10 million years can’t possibly be explained by mutational divergence of individual gene functions. Rather, it is more likely that all the animals involved in the Cambrian explosion were endowed with nearly the identical genome, with enormous morphological diversities displayed by multitudes of animal phyla being due to differential usages of the identical set of genes. This is the very reason for my proposal of the Cambrian pananimalia genome. This genome must have necessarily been related to those of Ediacarian predecessors, representing the phyla Porifera and Coelenterata, and possibly Annelida. Being related to the genome – possessed by the first set of multicellular organisms to emerge on this earth, it had to be rather modest in size. It should be recalled that the genome of modern day tunicates, representing subphylum Urochordata, is made of 1.8 x 10^8 DNA base pairs, which amounts to only 6% of the mammalian genome (9). The following are the more pertinent of the genes that were certain to have been included in the Cambrian pananimalia genome.”The bold is my emphasis. I trust you can see the problem here. So, Meyer makes a single goddamn reference to support the claim that the Cambrian explosion required a lot of innovation of new proteins, folds, cell-types and so on. What do we find in that references? That Ohno is suggesting the direct opposite, that he is in fact supporting the standard evo-devo view that few regulatory changes were what happened, that the genes and proteins were already present and had long preceding evolutionary histories.
Once again, Rasmussen hasn’t done his homework. A little digging on my part revealed that Dr. Meyer had previously discussed the Dr. Ohno’s claims at considerable length and responded to those claims, in his 2001 paper, The Cambrian Explosion: Biology’s Big Bang, which he co-authored with Paul Nelson and Paul Chien (bolding mine – VJT):
Ironically, even attempts to avoid the difficulty posed by the Cambrian explosion often presuppose the need for such foresight. As noted, Susumo Uno, the originator of the hypothesis of macroevolution by gene duplication, has argued that mutation rates of extant genes are not sufficiently rapid to account for the amount of genetic information that arose suddenly in the Cambrian.114 Hence he posits the existence of a prior “pananimalian genome” that would have contained all the genetic information necessary to build every protein needed to build the Cambrian animals. His hypothesis envisions this genome arising in a hypothetical common ancestor well before the Cambrian explosion began. On this hypothesis, the differing expression of separate genes on the same master genome would explain the great variety of new animal forms found in the Cambrian strata.
While Ohno’s hypothesis does preserve the core evolutionary commitment to common descent (or monophyly), it nevertheless has a curious feature from the standpoint of neo-Darwinism. In particular, it envisions the pananimalian genome arising well before its expression in individual animals.115 Specific genes would have arisen well before they were used, needed or functionally advantageous. Hence, the individual genes within the pananimalian genome would have arisen in a way that, again, would have made them imperceptible to natural selection. This not only creates a problem for the neo-Darwinian mechanism, but it also seems to suggest, as Simon Conway Morris has recently intimated,116 the need for foresight or teleology to explain the Cambrian explosion. Indeed, the origin of a massive, unexpressed pre-Cambrian genome containing all the information necessary to build the proteins required by not-yet-existent Cambrian animals, would strongly suggest intelligent foresight or design at work in whatever process gave rise to the pananimalian genome. (pp. 31-32)
In short: Dr. Meyer was not only aware that Dr. Ohno had proposed the existence of a pananimalian genome; he also explicitly referred to it in his 2001 paper, in order to demonstrate that Intelligent Design would be the best explanation of such a genome.
I’ll leave it to my readers to decide whether it is Dr. Meyer or Rasmussen who is guilty of “extremely shoddy scholarship.” Let me conclude by recalling an old saying: “People who live in glass houses shouldn’t throw stones.”
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