As <i>Darwin's Doubt</i> Is Released, Science Journals Confirm the Reality and "Mystery" of the Cambrian Explosion - Evolution News & Views

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As Darwin's Doubt Is Released, Science Journals Confirm the Reality and "Mystery" of the Cambrian Explosion

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With Stephen Meyer's new book, Darwin's Doubt: The Explosive Origin of Animal Life and the Case for Intelligent Design, out this week and catching some noteworthy attention, recent articles in leading scientific journals are confirming some of his key arguments about the Cambrian explosion. The two arguments I have in mind are: (1) that the Cambrian explosion was a real event in the history of life, and (2) that standard unguided evolutionary theories have failed (thus far, at least) to explain it.

A new article in the journal Science endorses both arguments (1) and (2):

The Ediacaran and Cambrian periods witnessed a phase of morphological innovation in animal evolution unrivaled in metazoan history, yet the proximate causes of this body plan revolution remain decidedly murky. The grand puzzle of the Cambrian explosion surely must rank as one of the most important outstanding mysteries in evolutionary biology. (emphasis added)

These are, in fact, some of the main points in Darwin's Doubt. The first section of the book is titled 'The Mystery of the Missing Fossils,' and it traces how evolutionary biologists and paleontologists have failed to explain the Cambrian explosion. As Meyer writes in the prologue:

The book is divided into three main parts. Part One, "The Mystery of the Missing Fossils," describes the problem that first generated Darwin's doubt -- the missing ancestors of the Cambrian animals in the earlier Precambrian fossil record -- and then tells the story of the successive, but unsuccessful, attempts that biologists and paleontologists have made to resolve that mystery. (p. xiv)
Of course many evolutionary scientists do continue to try to solve the "puzzle" of the Cambrian explosion, and the article cited above from Science goes on to review a new book by Douglas Erwin and James Valentine on the Cambrian explosion. I'll have more to say about that book in the future, but let it suffice to say, Erwin and Valentine also admit that material evolutionary explanations have yet to resolve the Cambrian enigma.

Another recent article from the latest issue of the journal New Scientist also acknowledges that the Cambrian explosion was a real event. The language is striking:

Life on Earth experienced a singular revolution just over 500 million years ago. In a geological blink of an eye, most groups of the animal kingdom appeared in the Earth's oceans and then diversified. The acquisition of skeletons, the advent of predation and the rise of complex ecosystems all occurred in what's known as the Cambrian explosion of marine animals. Life took such a giant leap forward in abundance and complexity during the Cambrian that the rock record itself was indelibly changed. (emphasis added)
The New Scientist article contributes to the chorus of scientific papers admitting the difficulties that the Cambrian explosion have posed for Darwinian theory -- also known as "Darwin's dilemma":
Evolutionary change isn't supposed to happen so abruptly, at least not according to Charles Darwin. "Darwin's dilemma" over the Cambrian explosion was explained away in his On the Origin of Species as an artefact of an incomplete geological record, one that failed to preserve fossils of a long Precambrian history of slow-paced animal evolution. A century and a half of study has shown that Darwin was right - animals do indeed have a Precambrian origin. A fossil record of that long history of simple bodies and behaviours has now been uncovered, proving that the Cambrian explosion was a real evolutionary phenomenon that needed to be explained. (emphasis added)
Of course in Darwin's Doubt, Stephen Meyer explains in great detail that the supposed "long" Precambrian history of animal evolution is neither documented by the fossil record nor by the genes of living animals. The chapters that discuss this topic -- three through six -- are some of my favorite in the book. In that regard, New Scientist isn't too far off in saying that "A fossil record of that long history of simple bodies and behaviours has now been uncovered" -- but what they don't mention is that the fossil organisms we've uncovered from the Precambrian had "bodies" that were so "simple" that they cannot explain the sudden burst of complex animal form that appears in the Cambrian.

The New Scientist article then goes on to repeat the hypothesis of a paper published in Nature from last year, which argued that weathering of rocks might have fed large amounts of sediment into the ocean, which allowed for the evolution of biomineralization of skeletons and shells in various Cambrian animals. A day late and a dollar short, Jerry Coyne is currently touting this New Scientist article (and the year-old Nature paper it references) as a possible "explanation" for the Cambrian explosion, apparently unaware that we responded to that paper last year here on ENV when it first came out in an article titled "Does Lots of Sediment in the Ocean Solve the "Mystery" of the Cambrian Explosion?" As I wrote:

Now, a skeptic might reply that we don't observe sediment in the ocean abruptly causing increases in the information content of genomes, much less do we have any experience with sediment creating new body plans. That sounds, in fact, like quite reasonable grounds for skepticism.

But this paper has no interest in explaining the origin of new information required to build the complex body plans that appear abruptly in the Cambrian explosion. It really isn't explaining the Cambrian explosion at all. Rather, it's trying to explain away the Cambrian explosion.

At base the Nature paper was just promoting a mildly different version of the artifact hypothesis. In Darwin's Doubt, Meyer also explains in great detail why such artifact hypotheses have failed to explain the Cambrian explosion.

Finally, there's an article in The Economist from back in March of this year. (Yes, I know, The Economist isn't a scientific journal, but it's a respected academically oriented news outlet, citing mainstream scientists, so bear with me a little.) It too endorsed both arguments (1) and (2) made by Meyer, i.e., that the Cambrian explosion was a real event and remains unexplained by evolutionary biologists:

Among the mysteries of evolution, one of the most profound is what exactly happened at the beginning of the Cambrian period. Before that period, which started 541m years ago and ran on for 56m years, life was a modest thing. Bacteria had been around for about 3 billion years, but for most of this time they had had the Earth to themselves. Seaweeds, jellyfish-like creatures, sponges and the odd worm do start to put in an appearance a few million years before the Cambrian begins. But red in tooth and claw the Precambrian was not -- for neither teeth nor claws existed.

Then, in the 20m-year blink of a geological eye, animals arrived in force. Most of the main groups of the animal kingdom -- arthropods, brachiopods, coelenterates, echinoderms, molluscs and even chordates, the branch from which vertebrates went on to develop -- are found in the fossil beds of the Cambrian. The sudden evolution of this megafauna is known as the Cambrian explosion. But two centuries after it was noticed, in the mountains of Wales after which the Cambrian period is named, nobody knows what detonated it. (emphasis added)
Meyer would contest such a long duration of the Cambrian explosion, as his book cites peer-reviewed papers from top scientific journals showing that the primary burst of the explosive appearance of animals was only 5 to 10 million years, and perhaps even less. But whatever the precise length, it's clear that mainstream evolutionary scientists agree that (1) the Cambrian explosion was a real event and not just an artifact of an imperfect fossil record, and (2) the abrupt appearance of new complex animals forms Cambrian explosion has posed problems for evolutionary biology -- problems that remain unresolved today. You won't find a more comprehensive discussion of why this is the case than you will in Darwin's Doubt.


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