Won’t somebody, somewhere in a major journal really tackle the greatest problem of the Cambrian explosion — the origin of new genetic information? Stephen Meyer’s book Darwin’s Doubt has been out for almost two years now. Evolutionary paleontologists surely know about him and his book, but once again, PNAS has published another paper that glosses over the problem that Meyer raises. (See here for a previous outing.)
If the authors Lin Na and Wolfgang Kiessling haven’t heard about it over there in Germany, surely the honchos at the National Academy of Science know about it. Wouldn’t they have told them in the review process, "Hey guys, you really need to talk about the information problem here." But, sad to say, the gloss goes on, putting another coat of whitewash over the major issue of the Cambrian event.
Animals just appear and emerge, as if out of a magician’s top hat:
Therefore, the increase of geodisparity we observe during the early Cambrian could be due to the widespread appearance of animals with larval stages combined with continental disassembly. In other words, biological innovation — the evolution of larval stages — in tandem with supercontinent breakup best explains the increase of geographic beta diversity. Our study provides evidence for niche partitioning, plate tectonics, and key innovations as strong and persistent evolutionary forces, and the Cambrian radiation is no exception, although it was more substantial in quality than later radiations. Future work should explore the links between the ecological dynamics described here and the astonishing increase of morphological disparity in the early Cambrian. [Emphasis added.]
Since scientists can at times be masters of obfuscatory jargon, let’s put this into plain English. Tell us, Drs. Na and Kiessling, how did almost twenty new complex body plans appear suddenly in the fossil record, without precursors? "Well, they appeared." But how? "Well, they’re innovators. They invented themselves." How can an animal plan its own innovations? "One idea is that a supercontinent broke up, providing them with new opportunities to invent things. Astonishing how they did it, I must say."
This is SO dissatisfying. How can they get away with it, year after year? It’s now 155 years since Darwin admitted that the Cambrian radiation posed the biggest problem to his theory. The fossils he thought would fill in the gaps have not materialized; in fact, they are wider now than Darwin realized. These authors admit that the rise in diversity and disparity was rapid, global, and unprecedented, occurring right in the early Cambrian.
With each new paper, our hopes go up that someone finally will buck up and face up to the real problem instead of assuming evolution’s unguided processes can work miracles.
The paper has 71 references. All the usual suspects are there: Erwin, Valentine, Marshall, Sean Carroll, and others. Simon Conway Morris and David Raup, their views mildly non-conformist, get a passing nod. But not a single serious Darwin skeptic is mentioned in the text or the notes. The NAS seems to have a policy; if we ignore them, maybe they’ll go away. Even Stephen Jay Gould was passed over, perhaps because his views on punctuated equilibria still sting in the gradualists’ eyes.
The Cambrian Explosion has been characterized as the rapid increase of both biodiversity and morphological disparity. The causes of this unique evolutionary radiation have been suggested to be abiotic, ecologic, and genetic factors and their complex interplay. Here, we derive potential triggers of the Cambrian radiation from the way diversity was partitioned geographically and environmentally during the main diversification phase.
Let’s take a look at the three "strong and persistent evolutionary forces" that they say caused the Cambrian explosion.
- Niche partitioning: The tale here is that as an ecological niche becomes filled with new species, it contracts. The contraction leads to partitioning. At first, there’s lots of space for newcomers. Competition is low and diversity is rapid. As competition grows, there’s more turnover of species, and some groups break away into other niches. Major problem: where do the new species come from? Oh, they just appear by evolution, silly. Didn’t we tell you already? Niche partitioning is a "strong and persistent evolutionary force"!
- Plate tectonics: The supercontinent Pannotia busted up. Think of all the new niches formed! A wonderland of possibilities opened up for evolution to work its magic, filling up all the niches with endless forms most beautiful.
- Key innovations: The new creatures invented skeletons and larval stages. Then, predators appeared by evolution, ramping up the need for more innovations. One is reminded of Carl Sagan’s verbal leapfrogging, like "Eyes evolved, and now the cosmos could see."
If this isn’t arrant handwaving, then it’s unmitigated gesticulating. They’re treating evolution like a magic wand that takes any empty space and fills it with trilobites, worms, crustaceans, arthropods, and mollusks. "Come forth!" Evolution cries; "this niche is made for you!"
Speaking of predators, a new Cambrian predator, somewhat similar to Anomalocaris, was found in the fantastic new Cambrian fossil bed in Canada named Marble Canyon, about 25 miles away from the famous Burgess Shale. This six-inch-long swimming predator, Yawunik kootenai, is the most abundant large species found at the site. It’s being called a "stem arthropod," part of the same group that contains spiders and lobsters. The University of Toronto describes it:
What do butterflies, spiders and lobsters have in common? They are all surviving relatives of a newly identified species called Yawunik kootenayi, a marine creature with two pairs of eyes and prominent grasping appendages that lived as much as 508 million years ago — more than 250 million years before the first dinosaur….
The study presents evidence that Yawunik was capable of moving its frontal appendages backward and forward, spreading them out during an attack and then retracting them under its body when swimming. Coupled with the long, sensing whip-like flagella extending from the tip of the claws, this makes the frontal appendages of the animal some of the most versatile and complex in all known arthropods.
In addition to eyes and jointed appendages, this animal clearly had a central nervous system, a gut, and reproductive organs. How much new genetic information would be required to build an animal like Yawunik, with all its specialized "innovations"? Is it sufficient to say that it "appeared" because a niche was available for it? Did plate tectonics do it?
Meyer’s book awaits a response. Ignoring the question does not qualify as an answer.
Image: Yawunik kootenayi fossil, by Robert Gaines via University of Toronto.