Letter to the Editor
A Response to Morton's Critical Review of Creation, Evolution, and Modern Science
Executive Director, Probe Ministries
From:PSCF 53 (June 2001): 137-139.
Glenn Morton offered a review of the book, Creation, Evolution, and Modern Science (PSCF 53 [March 2001]: 63-4), which I edited and wrote most of the chapters. Even a cursory reading of the book itself will allow most to realize that Morton's negative and hostile review fails to reflect accurately the book's intent, content, and audience. I offer a few rebuttals and will let the reader decide how to interpret Morton's other comments. It seems clear to me that Morton expects any book dealing with scientific issues to be written on a scientific scholarly level. My experience has been that this approach turns the scientific novice away, therefore defeating the purpose of education. First, I will address Morton's factual charges and then answer his concern of the level of scholarship.
Morton chides me for not quoting from Cambrian explosion authority Simon Conway Morris's 1998 book, The Crucible of Creation: The Burgess Shale and the Rise of Animals (Oxford University Press), in the chapter on the Cambrian explosion. Morton leaves the impression that if I had, I would not have represented the Cambrian as exhibiting the first example of all but one animal phylum. Morton says: "Nowhere does Bohlin acknowledge the fact that five phyla are now found in the pre-Cambrian including sponges, molluscs, worms, jellyfish, and arthropods." The reason I did not acknowledge this "fact" is that it is not a fact but an opinion, and a controversial one at that. Let's let Conway Morris speak for himself.
Referring to the resemblance of the Ediacaran fauna to jellyfish (cnidarians) and worms, Conway Morris says:
For many years paleontologists have been busy comparing Ediacaran fossils to supposed modern- day equivalents, such as jelly-fish or worms. A more careful scrutiny reveals, however, some significant problems. Certainly there are similarities, but they are worryingly imprecise" (The Crucible of Creation, p. 28).
Later, Conway Morris admits that it is his opinion that many of the Ediacaran fossils are cnidarians. He says: "In my opinion not only are the frond-like Ediacaran fossils cnidarians, but so too are many of the other fossils. What appears to be an intriguing absence from the Ediacaran faunas, however, are the sponges."
Conway Morris goes on to cite a recent find of sponges (porifera) in the Ediacaran of Australia by Gehling and Rigby. But even the UC Berkeley website, usually more up-to-date than print media, lists this find as a "probable" sponge (www.ucmp.berkeley.edu/porifera/poriferafr. html) and still lists sponges as first appearing in the Cambrian (www.ucmp.berkeley.edu/phlya/metazoafr.html). What emerges is that sponges are found unequivocally in the Cambrian, and their presence earlier in the fossil record is controversial. This hardly qualifies as fact.
In turning his attention away from sponges and cnidarians, Conway Morris curiously remarks that they are primitive and can be considered evolutionary dead-ends. In a note, he states:
Sponges and cnidarians are so different that it is difficult to imagine how the transitions between them, or between cnidarians and the platyhelminthes were achieved. Most probably this is because the intermediate forms are now extinct, leaving only speculation. The bulk of evidence certainly suggests that metazoans are monophyletic; but the possibility that the sponges and cnidarians had independent origins from separate protistan an alternative, albeit unpopular, possibility (The Crucible of Creation, pp. 35-6).
So, even if scientific opinion unites behind the presence of sponges and cnidarians appearing in the Precambrian, that may not help resolve the riddle of the Cambrian explosion.
Next Conway Morris addresses possible precursors of annelids and arthropods in the Precambrian, which Morton also labels as firmly established.
What about the more advanced groups that must have given rise to the bulk of the Cambrian faunas? Can they be identified amongst the Ediacaran fossils? There are some candidates. These fossils, which show a variety of forms, have clear bilateral symmetry, often with a well-defined anterior end. In addition, some types may show transverse segmentation. These fossils are probably on the route leading to groups such as arthropods and annelids. Their exact place in the scheme of metazoan phylogeny is nevertheless still controversial.
In a figure legend on page 27, Conway Morris admits that the relationships of Dickinsonia costata to known groups are uncertain and that its segmentation only "suggests that Dickinsonia costata may be related to groups such as the annelids." Use of such terms as "candidates," "probably," "controversial," "uncertain," and "suggest" do not constitute a fact in anyone's lexicon.
And regarding the fifth taxon in which I am accused of getting my facts wrong, the molluscs, a recent news article in Science (Vol. 291 [23 March 2001]: 2292), shows I am at least in good company. Writing for Science, Erik Stokstad reports on the first example of an aplacophoran (shell-less molluscs inhabiting today's sea-floor that are thought to resemble the first molluscs). He states: "Yet none had been found in the fossil record of mollusks, which stretches back more than 500 million years to the early Cambrian--until now." The "until now" refers to a specimen found not in the Precambrian, but the Silurian from Herefordshire, England.
Morton also chastises me for claiming the Cambrian only lasted for 5-10 million years. I did not. The five to ten million-year time frame referred only to the Cambrian explosion, not the Cambrian period in its entirety. I corrected Morton on this, but he apparently did not believe me. Morton is confused here too, since he states in his abstract from his article on page 42 of the same PSCF issue that "evidence arises indicating that the Cambrian explosion was not very explosive. In contradiction to many apologetical claims, it occupied a period of nearly 100 million years." Yet according to Morton's acknowledged authority, Conway Morris says:
The term "explosion" should not be taken too literally, but in terms of evolution it is still very dramatic. What it means is the rapid diversification of animal life. "Rapid" in this case means a few million years, rather than the tens or even hundreds of millions of years that are more typical when we consider evolution in the fossil record (Crucible of Creation, pp. 31-2).
Now I know that Morton did not mean to say that the Cambrian explosion lasted nearly 100 million years, but that is what he appears to have said.
Also, Morton says there are at least thirteen phyla that make their appearance after the Cambrian. While Morton does not list them in the review, he does in his article (PSCF 53, no. 1 [March 2001]: 44). Morton knows these are nearly all plant phyla because I corrected him on this too. Some are not even phyla, but sub-phyla and classes. Plants are never considered part of the Cambrian explosion and I explicitly state animal phyla in the book. The one from Morton's list of thirteen that is not a plant taxon, the Bryozoa, is the one I mention as an exception in the book. Why this charge remains in his review I can only guess.
From what I have been able to glean, it is Morton who has his facts wrong. However, one may rightly ask the reason why all of this detail is not found in Creation, Evolution, and Modern Science. It is that I am not writing in Science, Nature, or the Journal of Paleontology. Creation, Evolution, and Modern Science is not written to the scientific community. I made this point to Morton when he graciously allowed me a preview of his review. Obviously Morton was not impressed. I believe my statements regarding the Cambrian are accurate though perhaps not as precise as Morton would prefer. It is a longstanding tension in writing on science for the public.
While I found much to disagree with Carl Sagan's world view, I admired his gift of communication. Yet, many of his colleagues in science felt he simplified to such an extent as to be inaccurate. Sagan was frequently imprecise, but usually accurate. Science writing for the general public is a difficult task, constantly balancing accuracy and comprehension. I have been guilty in the past of being so accurate and precise in lectures and articles for the public that people become impressed, but come away having learned nothing. Obviously Morton believes I have sacrificed accuracy for readability. I disagree.
This also explains why I did not use more references from the scientific literature, which Morton also declares unscholarly. Specifically he derides my extensive use of a cover story from Time (December 4, 1995) on the Cambrian explosion. Like it or not, science is rapidly becoming second only to law as a somewhat disreputable profession in the general public. They unfortunately have no interest or inclination to read Science, Nature, or any other scientific publication. Scholarly precision that leaves the eyes glazed over only exacerbates the problem. I used the Time article precisely because people were likely to actually have read it or at least have access to it if they had not. The Time piece also committed many of the errors of communicating about evolution to the public that I wanted to discuss and it quoted many scientists more candidly than scientific literature ordinarily does.
Finally, what left me most perplexed about Morton's review was the last sentence. "Unfortunately, as Bohlin told me, a bad review here may help his sales, I fear he is correct." Morton implies I am more interested in sales than in truth. I want to assure the readers of PSCF that while I did make the comment to Morton, it was fully intended as a joke. That Morton would represent this good-natured statement as a serious reflection of my attitude was extremely disappointing, as was the entire review.