Darwin’s Doubt – Chapter 2 Part 2
And so we begin our wonderful journey into the world of the Burgess Shale. Meyer entitles this section “The Bestiary”. As any good role-playing gamer will tell you, the Bestiary is where we get descriptions of animals.
I have a minor editing quibble here (and I know this is pot calling the kettle black, because I’m not very good at it), but a further discussion of the discovery of the Burgess Shale should have been in the introduction. As it is, Meyer talks for another page about the discovery of the shale layer. He quotes Gould’s Wonderful Life: The Burgess Shale and the Nature of History … again.
“Consider the primal character of this tale—the lucky break provided by the slipping horse, . . . the greatest discovery at the very last minute of a field season (with falling snow and darkness heightening the drama of finality), the anxious wait through a winter of discontent, the triumphant return and careful, methodical tracing of errant block to mother lode.”
Oh for crying out loud. There’s those damn ellipses again. Hmmm… this time, they appear to be used correctly. The missing bit is merely a figure notation.
Meyer continues on asking why the scientific community would present a fictitious description of the event rather than the majestic beauty of reality. I ask myself the same question. I don’t know the answer. No one knows the answer as the players are all dead by now. This did happen well over 100 years ago.
This whole thing is a legend about the discovery of the Burgess Shale. While moderately entertaining, it’s not really important, other than as an example of the poetic license of people.
Now, let’s get to it. One of the reasons that I’ve been delayed on this project is because I’ve found, read, and reviewed almost a dozen peer-reviewed papers on the subject that Meyer is talking about. [One other reason is I've also picked up a new research paper reader and organizer. ] While I have a few minor quibbles with what Meyer reports on page 29, it’s mostly accurate.
Marrella isn’t always divided into 26 segments, but range from 17-26 (as the paper that Meyer references explains).
No, the problem I have is in the footnote. Who reads footnotes right? In footnote #4 Meyer says:
A distant relationship between Marrella and chelicerates is the currently favored hypothesis.
And he provides the two references below (and previously linked to in this post).
Skimming ahead, we see Meyer complaining about the lack of previous fossils and this attempting to cast doubt on evolution. Why this is a problem becomes evident when one actually reads the footnote and the paper that is referenced.
One of the articles that Meyer references for the idea about Marrella is called “Arthropod Origins”. Which is an interesting choice for Meyer since it describes the origin of arthropods, which Meyer says is impossible without intelligence. Now Meyer only mentions this in passing, but let me jsut quote from the conclusion of the paper.
There is strong evidence that lobopodians and arthropods belong to the ecdysozoan branch, but they should have separated before the loss of the characteristic plesiomorphic circulatory system, lacking in all ecdysozoan worms. The compact character of the tree may mean that the “founders” of the four post-flatworm groups were all closely related. Lobopodians and arthropods, representing an early offshoot from ecdysozoans, would therefore also be fairly close to the origins of deuterostomes, bryozoans and lophotrochozoans. This would help explain the extreme difficulties to understand the relationships of arthropods and other animal phyla, whatever method is used.
I know what you’re thinking… “What. The. Fuck??” A picture is worth a 1000 words, so here is what the authors have done.
This is a cladogram of the origins of arthropods. The letters are some of the characters shared (or lost) that in all groups after that letter. For example, both tardigrades (which are awesome) and Arthropods have a full loss of cilia (x in the cladogram). This chart, based on evidence, on the morphology of the organisms pretty much refutes Meyer’s entire point about the Cambrian phyla. They didn’t appear fully formed. The relationships between these groups shows that they are related by common ancestry.
Rotifera is the phylum of the “wheeled animals” and there are thousands of species in several classes. These are alive today and first appeared… well, we’re not sure exactly. These are microscopic creatures and the obviously won’t fossilize well. However, Rotifers are related to Molluscs and Annelids, and we have very good phylogenetic evidence that rotifers branched off before the common ancestor of molluscs and annelids. Since we see clear fossils of both molluscs and annelids in the Cambrian, we can infer that the line that leads to modern rotifers must also have already branched off by that time.
I could go on, but this is long, has taken a lot of effort and I could right another 2,000 words just on the groups in that cladogram. Each one with significant references (see below for a few on rotifers) explaining that these are early or pre-cambrian groupings.
So far, we are four paragraphs into The Bestiary. I want to spend some effort on the rest of the section as Meyer makes some claims and decisions not for the purpose of advancing science, but to advance a particular notion… which I will attempt to refute and explain why he’s wrong… again.
Let me add a quick note about creationism and it’s modern interpretation, Intelligent Design, here. I’ve heard (many, many times) that the appearance of common ancestry is the same as the appearance of common design. That we can infer common design, basically part-reuse, in organisms that are related by, for example, the characters in the cladogram above.
In that case, so what? In that case, if the creationists wish to make that argument, then they have doomed ID. Why? Because there are two competing notions; ID and evolution. In this case, the creationists say that ID predicts the same thing that evolution does. OK, fine, these common traits are not discriminatory between evolution and design. This is because both notions predict the exact same thing. It’s useless to even talk about it and it is certainly not evidence for Intelligent Design.
However (and you knew this was coming right), evolution has a mechanism for that commonality. That is, the concept of heredity and speciation. ID doesn’t have a mechanism (both Behe and Dembski, two leaders of the ID movement, have publicly stated that there is no mechanism for ID). Since that is the case, there is a difference between evolution and ID. Evolution predicts a specific mechanism and ID doesn’t. If that mechanism is found, then evolution is strengthened and ID has to go back to the drawing board. Even a casual search of peer-reviewed research will yield thousands of speciation events and thousands of instances of proteins, DNA, and RNA sequences changing over time in one species or group and not changing in another species or group (Richard Lenski’s work on E. coli for example).
So, evolution is supported and ID fails.
García-Bellido, D.C. & Collins, D.H. A new study of Marrella splendens (Arthropoda, Marrellomorpha) from the Middle Cambrian Burgess Shale, British Columbia, Canada. Canadian Journal of Earth Sciences 43, (2006).
Bergström, J, and X Hou. “Arthropod origins”, 2003. Available: http://mzp.cz/ris/ekodisk-new.nsf/1a76d1df1a0e29f0c1256e2800520b9d/9a21746463a798e9c125708f002d7766/$FILE/str.%20323-334.pdf.
Garey, J. R., Schmidt-Rhaesa, A., Near, T. J., Nadler, S. A. 1998. The evolutionary relationships of rotifers and acanthocephalans. Hydrobiologia 387-388: 83-91
Wirz, A., Pucciarelli, S., Miceli, C., Tongiorgi, P., Balsamo, M. 1999. Novelty in phylogeny of Gastrotricha: Evidence from 18S rRNA gene. Molecular Phylogenetics and Evolution 13(2): 314-318.