Science & Faith
11/4/13 at 08:20 PM 7 Comments

Final Thoughts on Marshall's Failed Critique of Meyer's "Darwin's Doubt" (Time to Change the Subject?)

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Today we will see a few more indications of the woeful inadequacy of Charles Marshall's critique of Meyer's book Darwin's Doubt. This will complete a series of posts on Marshall vs. Meyer that are backward linked: start here and follow the links backward in time if you missed my earlier posts.

In previous posts I've highlighted and further explained how Meyer refutes Marshall's main two contentions that:

  1. The Cambrian explosion would not have required a significant increase in new genetic information.
  2. Meyer's positive argument for intelligent design, based on the need for an increase in genetic and epigenetic biological information, represents a purely negative "god-of-the-gaps" argument.

In this concluding blog we will consider a few criticisms that Marshall makes of Darwin's Doubt.

Marshall writes:

Meyer completely omits mention of the Early Cambrian small shelly fossils and misunderstands the nuances of molecular phylogenetics, both of which cause him to exaggerate the apparent suddenness of the Cambrian explosion.

Marshall's point is that Meyer treats the "Cambrian explosion" as 10-million-year event rather than a 25-million-year one, thus exaggerating its brevity and making it look to be more of a challenge to neo-Darwinism than it might otherwise appear. This is a curious criticism coming from Marshall who claims to offer a careful review of Meyer's book for several reasons.

1. Meyer does mention the small shelly fossils on page 425 of Darwin's Doubt, where he writes:

The Cambrian period 543 mya is marked by the appearance of small shelly fossils consisting of tubes, cones, and possibly spines and scales of larger animals. These fossils, together with trace fossils, gradually become more abundant and diverse as one moves upward in the earliest Cambrian strata (the Manykaian Stage, 543-530 mya).

As Luskin explains on Meyer's behalf (answering Marshall):

Nevertheless, although Meyer discusses the small shelly fossils, he does not treat them as a solution to the problem of the explosion of morphological novelty that arises later in the Cambrian period. The small shelly fossils appear in the fossil record at the base of the Cambrian period about 542-543 million years ago. The main pulse of morphological innovation that Cambrian paleontologists commonly refer to as the "Cambrian explosion" first begins about 530 million years ago and then lasts about 10 million years through the Tommotian and Adtabanian stages of the Cambrian period. During the first 5-6 million year stage (the Tommotian) of the explosion, between 14-16 novel phyla first appear in the fossil record.1 Without actually asserting that the small shelly fossils somehow explain the subsequent explosion of all these novel forms of animal life (or even that the small shelly fossils represent ancestors to all, or some, of these forms), Marshall faults Meyer for not treating them as part of the Cambrian explosion. [read more of Luskin's defense of Meyer here]

2. Another reason we should find it odd that Marshall critiques Meyer for leaving the earlier Cambrian appearance of small shelly fossils out of the official timeline of "the Cambrian explosion" is that Marshall himself in previous publications has used the term "Cambrian explosion" to refer either to the main pulse of biological innovation that is about 10 million years (as does Meyer, and which is a very common terminological practice among Cambrian experts), or the longer 25 million year period.

For example, Marshall co-writes with James Valentine:

By the beginning of the Cambrian Period, near 543 million years ago, a few kinds of 'small shelly' fossils are found, <2mm in largest dimension. The small shellys rose to a peak in abundance and diversity during the period from 530 to 520 million years ago, when representatives of living phyla are found among them. During that same period, a chiefly larger-bodied invertebrate fauna of up to a dozen phyla, and including many soft-bodied forms, is also first represented by fossils. This geologically abrupt appearance of fossils representing quite disparate bodyplans of many living metazoan phyla is termed the Cambrian explosion..." (Charles R. Marshall and James W. Valentine, "The Importance of Preadapted Genomes in the Origin of the Animal Bodyplans and the Cambrian Explosion," Evolution 64-5 (2010): 1189-1201, as cited here in footnote #2],

The emphasis in the above quotation is mine to show that Marshall in this case uses the term "Cambrian explosion" in precisely the same way as Meyer, and mentions the earlier appearance of small shelly fossils before the "Cambrian explosion," exactly as Meyer does. Strange, then is the fact that Marshall finds fault in Meyer when Meyer does the same thing.

So, in summary, Marshall falsely accuses Meyer of not mentioning the earlier small shelly fossils, and even worse, Marshall charges Meyer with exaggerating the suddenness of the Cambrian explosion even though Marshall himself has, at times, advocated the exact same chronological framework for the Cambrian explosion. Yet, Darwinists here in CP comments, and elsewhere in the Internet world, have been gushing over Marshall's alleged defeat of Meyer in a mere eight-paragraph review that turns out to be a flop. Is this not an amazing disconnect with reality? The power of the Darwinian paradigm can bend minds to behave in curious ways.

But we're not done yet. It gets worse.

Meyer writes:

Marshall himself, like many other Cambrian experts, does not regard the small shelly fossils as obviously ancestral to most of the animals that arise in the main explosive period of the Cambrian radiation. In one 2006 paper he depicts them as (apparently) disconnected from the later more significant pulses of morphological innovation.6 In fact, Marshall notes repeatedly that the small shelly fossils are "largely problematic" and "hard to diagnosis even at the phylum level."7

Meyer then points out that such embarrassing passages from Marshall's own works is only half the story. He concludes his final response to Marshall's review with this:

In any case, treating the first appearance of the small shelly fossils as the beginning of the Cambrian explosion does little to explain the main pulse of the morphological innovation that occurs later during the 10-million-year window that paleontologists commonly designate as "the explosion." As I acknowledge in Darwin's Doubt, it is entirely possible to assign a different duration to the "Cambrian explosion" depending upon how many separate paleontological events scientists choose to include within that designation. Nevertheless, quibbling of that sort reduces the debate to one of semantics. The key question is not how many different events should be included within the designation "Cambrian explosion." Nor is it about the total amount of time that some arbitrarily designated series of separate paleontological events covers. Instead, the key question is what caused the discontinuous appearance of morphological novelty within specific, and measurably narrow, windows of geological time -- whatever we choose to call them. Thus, Darwin's Doubt focuses on the crucial Tommotian and Adtabanian stages of the Cambrian explosion -- where 13-16 new animal phyla arose within a 5-6 million year window -- as a defining challenge to the efficacy of the neo-Darwinian mechanism.9 Marshall doesn't explain how the origin of the small shelly fossils diminishes the problem of the origin of the morphological novelty within that window of time.

Moreover, as I discussed in a previous response to Marshall (and in Chapters 10 and 12 of Darwin's Doubt), even a duration of 25 million years would not appreciably diminish the problem facing contemporary evolutionary theory. In the first place, 25 million years would not provide enough opportunities for the mutation/selection process to search more than a tiny fraction of the relevant sequence spaces necessary to produce even a single new gene or functional protein.10 Second, the calculated waiting times required to evolve multi-mutation features also suggest that even pushing the beginning of Cambrian explosion back to the first appearance of the small shelly fossils, as Marshall suggests we should, does not provide enough time for many complex biological features to evolve.11 Marshall does not attempt to refute these experimentally based quantitative arguments. Consequently, it's hard to see how my decision not to make more of these enigmatic small shelly fossils in any way undermines the main arguments of Darwin's Doubt.

Does anyone out there still want to sing the praises of Marshall's alleged defeat of Meyer's book? I already sensed that Darwinists commenting under my last post in this Marshall-Meyer series were looking for ways to change the subject. Peace.

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