The Great Cambrian Whitewash
Stephen Meyer's book Darwin's Doubt has been out for almost three years. Paleontologist Mark McMenamin called it a "game changer for the study of evolution..." It has over 700 reviews on Amazon (78 percent five-star, 6 percent four-star). When it came out in 2013, it ranked #7 for hardback nonfiction on the New York Times bestseller list. And last year, a follow-up book, Debating Darwin's Doubt, addressed all the known objections to the original work.
To read most of the scientific journals, though, you would think they know nothing about this. Nature, PNAS, Current Biology, you name it: they avert their eyes from Meyer's 500-page challenge whenever they discuss the Cambrian explosion. (The journal Science is the noble exception.) It is simply not possible that the authors of these papers, and the editors of these journals, are unaware of the controversy. Meyer has raised a significant challenge to the usual Darwinian explanation for the sudden appearance of complex animal life in the fossil record. It's time for the journals to face it and engage the scientific debate.
The leading science journal Nature, sad to say, whitewashed the controversy once again in a recent piece, "What sparked the Cambrian explosion?" Author Douglas Fox gives the usual positivist spin:
An evolutionary burst 540 million years ago filled the seas with an astonishing diversity of animals. The trigger behind that revolution is finally coming into focus. [Emphasis added.]
Such writing has all the comfort of Pravda telling the captives behind the Iron Curtain, deprived of alternative sources of information, that the famine will soon be over. Science should abjure a closed society. Besides, journals cannot afford the luxury of one-sided propaganda in this internet age. You can't wall off information for long. Search on "Cambrian explosion" and critiques pop up for the entire world to see. Not the least of those is Darwin's Doubt. Journals look foolish when they adopt the three-monkey posture, "Hear no controversy; see no controversy; speak no controversy." The smart strategy is to deal with it openly, so that consumers in the marketplace of ideas can decide who has the better product.
What is implied by Nature's line that the trigger for the Cambrian explosion is "finally coming into focus"? It can only mean one thing. It's been out of focus till now. When you consider that the problem of the Cambrian explosion troubled Charles Darwin, it's a sad commentary on the ability of scientists to admit being unable to focus on a solution for 157 years. That's enough time for 31 Five-Year Plans proverbially launched by the dear leader of evolution to find the fossils that would support his theory.
But Nature isn't really looking for support. As doctrinaire believers in Darwin's "mechanism" of natural selection, they don't need support. It's self-evident to them that an "evolutionary burst... filled the seas with an astonishing diversity of animals." Douglas Fox just wants to help by finding the "trigger."
And what is that trigger that is finally coming into focus? Oxygen.
Sperling has looked for insights into Ediacaran oceans by studying oxygen-depleted regions in modern seas around the globe. He suggests that biologists have conventionally taken the wrong approach to thinking about how oxygen shaped animal evolution. By pooling and analysing previously published data with some of his own, he found that tiny worms survive in areas of the sea floor where oxygen levels are incredibly low -- less than 0.5% of average global sea-surface concentrations. Food webs in these oxygen-poor environments are simple, and the animals feed directly on microbes. In places where sea-floor oxygen levels are a bit higher -- about 0.5-3% of concentrations at the sea surface -- animals are more abundant but their food webs remain limited: the animals still feed on microbes rather than on each other. But around somewhere between 3% and 10% oxygen levels, predators emerge and start to consume other animals.
The implications of this finding for evolution are profound, Sperling says.The modest oxygen rise that he thinks may have occurred just before the Cambrian would have been enough to trigger a big change. "If oxygen levels were 3% and they rose past that 10% threshold, that would have had a huge influence on early animal evolution," he says. "There's just so much in animal ecology, lifestyle and body size that seems to change so dramatically through those levels."
This excerpt illustrates why airing of the controversy is so drastically needed. Fox's prose hardly rises to the level of fairy tale. Would anyone outside the iron curtain of Darwinian explanations fall for a "just add oxygen" theory for the emergence of a trilobite or Anomalocaris?
Meyer would grant Fox and Nature all the oxygen they could ever want. He would let them inject copious quantities of oxygen bubbles into the Cambrian oceans right at the start of the explosion. No trilobites would emerge, he would argue, because the Cambrian explosion is not about gases, triggers, or influences. It's about information: the specifications to build animal body plans. That is the central challenge that the journals ignore.
Fox whitewashes the problem by repeating the party line no matter what. He offers pipe dreams that solutions will come someday, as long as everyone holds to the dogma.
Understanding how oxygen influenced the appearance of complex animals will require scientists to tease more-subtle clues out of the rocks. "We've been challenging people working on fossils to tie their fossils more closely to our oxygen proxies," says Lyons. It will mean deciphering what oxygen levels were in different ancient environments, and connecting those values with the kinds of traits exhibited by the animal fossils found in the same locations.
Communist ideologues were masters at interpreting every economic condition, including the failures in Russia and the riches in the West, in terms of class struggle and economic determinism. Yet now we look back at the fruits of that closed system.
Science should abhor iron curtains. Nature's willful neglect of the controversy surrounding the Cambrian explosion subverts the ideals of science. Besides that, it just looks bad. What are they hiding behind that wall? What do they have to lose by engaging scientific challenges? Only the story that oxygen causes trilobites. That's a tale worth losing. The time for détente, for glasnost, has arrived. Good things follow.
Image credit: © Guerrieroale / Dollar Photo Club.