You remember Pravda and Izvestia, the official propaganda organs of the former USSR. (That’s the editorial offices of Pravda pictured above.) Having silenced the free press long ago, these “newspapers” were free to dole out the party line without opposition, giving the impression to unwary readers that there was no opposition. Well, here is a major science journal that followed this strategy.
A Treasure Trove
To celebrate its 25th anniversary, Current Biology offered a special issue on “The History of Life on Earth.” The 16 open-access articles amount to a treasure trove of evolutionary thinking on a wide variety of subjects: RNA World, insect evolution, bird evolution, and more — all presented by big-name Darwinian proponents who ignore alternative views. A case in point is the primer on “The Cambrian Explosion” by Derek E. G. Briggs. Any mention of critiques of the Darwinian explanation? Nope. Intelligent design? Are you kidding?
One might think that the editors would find it strategic to allay the fears of readers worried about the challenge to Darwinism raised, for example, by Stephen Meyer’s bestseller Darwin’s Doubt by answering it. Not at all. That seems a risky strategy, considering that Meyer and others cogently responded to their critics’ best objections in a follow-up book, Debating Darwin’s Doubt. It’s hard to imagine Briggs or the editors being unaware of these books. Apparently they think that enough of their readers don’t know of the controversy, or they don’t wish to give Meyer publicity.
It’s interesting to see what Derek Briggs is willing to admit about the Cambrian explosion (emphasis added):
- It’s real: “We now know that the sudden appearance of fossils in the Cambrian (541-485 million years ago) is real and not an artefact of an imperfect fossil record,” he says.
- It saw diverse body plans: “In effect, the major body plans or phyla were establishedduring the Cambrian explosion,” but how? (Keep reading.)
- Hard parts were not required: “Exceptionally preserved Cambrian fossil deposits, such as the famous Burgess Shale, yield examples of 14 of the 19 soft-bodied phyla” of the ~33 animal phyla recognized today.
- Not oddballs: “The affinities of some of the Cambrian creatures that were dubbed ‘weird wonders’ are still debated but phylogenetic analyses have shown that most of them are much less weird than first thought — they do not represent extinct higher taxa, but are early offshoots of the lineages leading to modern groups.”
- Complex parts: “Various arthropods from the Cambrian of China have recently been shown to preserve evidence of the brain and nervous system, which were fossilized in rapidly precipitating minerals,” Briggs says.
- No answers: “The drivers behind the Cambrian explosion were varied and complex, and there is no simple explanation of either the timing or ecological mechanism involved.” All he can do is offer possibilities.
- Bottom line: Briggs is still looking for clues about how “all the major animal groups evolved in a relatively short time during the Cambrian explosion.”
You see that Briggs doesn’t dispute the observable facts. He knows that the major animal body plans appeared quickly.
So What Is His Explanation?
- He stretches out the explosion, giving it the largest possible range of 56 million years. 10 million years is more widely accepted, but no matter how many years are granted, the problems of missing ancestors and abrupt appearances remain.
- He considers the Ediacaran period ancestral to the Cambrian, asserting that this resolves “Darwin’s dilemma” about the missing Precambrian fossils. “Darwin’s dilemma regarding the absence of Precambrian fossils was not resolved until the 1940s when a diversity of large animals of Ediacaran age (635-541 million years ago) was discovered in South Australia, providing spectacular evidence of life prior to the appearance of the first shells.” This is very misleading, as most biologists do not consider the Ediacaran organisms ancestral to the Cambrian animals.
- He makes the most of early arrivals: “However, a number of Ediacaran fossils are interpreted with reasonable certainty as early offshoots (stem taxa) of lineages leading to modern groups — including sponges (Palaeophragmodictya), cnidarians, and bilaterians such as molluscs (Kimberella) and possibly arthropods.” This misdirects attention from the complexity of these phyla, and fails to account for at least 15 more new body plans that exploded onto the scene in the early Cambrian.
- He puts a lot of trust in molecular inferences: “Molecular clock dates indicate that the ancestors of most modern marine phyla had evolved by the Ediacaran, but identifying their representatives, even among the remarkable range of Ediacaran forms, is not straightforward.” His conclusion is more confident: “Phylogenies calibrated by fossil occurrences allow molecular clocks to estimate the timing of branching even where fossil evidence is wanting.”
- He uses the power of suggestion: “The rise of oxygen levels in the earth’s atmosphere and oceans has often been implicated in initiating rapid diversification.” We’ve responded to this “oxygen theory” before. Another suggestion: “The rise of zooplankton allowed particles to sink to the sea floor as fecal material which significantly augmented the nutrient supply,” he speculates. “Such increases in environmental complexity during the Cambrian may well have resulted in a proliferation of diverse ecological strategies that were not present earlier.” Should we call this the crap theory?
- He offers promissory notes: “And in due course, experiments on the role of control genes in the development of animals from embryo to adult may provide clues to how all the major animal groups evolved in a relatively short time during the Cambrian explosion.”
Hoping for an Answer
Here’s another key passage expressing hope for an answer:
Although the fossil record is silent on mechanisms to explain how morphology could have evolved so rapidly, developmental biology investigates how genetic mechanisms affect body plans. Evolutionary developmental biology (evo-devo) may provide clues to how such a remarkable range of morphology evolved so quickly, at least in organisms amenable to experimental manipulation.
There’s really nothing new here. All these hypotheses have been answered in Darwin’s Doubt and Debating Darwin’s Doubt. Our job is to get the information past the censors, so that the organs of propaganda are defeated by free and open inquiry.
This article was originally published in 2015.