October 28, 2009 | David F. Coppedge

Cambrian Explosion Solved: Elementary, My Dear Darwin

Two articles announced solutions to the evidential problem that most troubled Darwin – the sudden appearance of complex animals at the base of the Cambrian fossil record.  Both of them involve chemical elements.  The only difference is which element.
    Science Daily announced a “Novel Evolutionary Theory For The Explosion Of Life.”  The article acknowledged that “The Cambrian Explosion is widely regarded as one of the most relevant episodes in the history of life on Earth, when the vast majority of animal phyla first appear in the fossil record.”  The article also acknowledged it to be a bit of a problem: “However, the causes of its origin have been the subject of debate for decades, and the question of what was the trigger for the single cell microorganisms to assemble and organize into multicellular organisms has remained unanswered until now.”  Sitting on the edge of our seats after this build-up, we look into the article for the solution.  An international team looked into the question.  It’s calcium, they announced with chutzpah:

The researchers succeeded to show that the massive and sudden surge in the calcium concentration of the Cambrian seawater — that is believed to be the result of volcanically active midocean ridges — not only initiated the buildup of calcified shells, but was also mandatory for the aggregation and stabilisation of multicellular sponge structures.  This allows, on the other hand, to formulate a novel theory where the geologically induced increase of marine calcium might be the key for understanding the Cambrian Explosion of Life.
    This paper constitutes the first research work where single molecule force spectroscopy studies have provided meaningful answers to such a deep evolutionary biology question as the origin of multicellular animals, and might represent a milestone for both disciplines and an example of how multidisciplinarity and collaboration are essential components of excellent contemporary science.

PhysOrg, on the other hand, had another element in mind to explain the “big growth spurts” in the evolutionary history of life.  They had two in mind: the origin of eukaryotes, and the Cambrian explosion.  “Scientists say the main driver of each growth step was a massive increase in the supply of oxygen, which is needed to convert food to the additional energy required for larger, more complex life forms.”  But if you give food to an athlete, does it increase his complexity?  How does that solve the problem?  The article presented the views of David Johnston of Harvard.  Sure enough, he thinks that size matters, and wrote a book called Why Size Matters.  “It is the supreme and universal determinant of what any organism can be and can do.”  Again, it is not clear why size alone creates complexity.
    So if the first eukaryotes started pumping oxygen into the atmosphere 2.35 billion years ago, why did it take so long for the Cambrian growth spurt?  “Fueled by more oxygen, eukaryotes took another enormously significant stride: They started to combine into larger organisms containing multiple cells, organs and tissues.”  This idea should be testable.  People in oxygen tents should be examined to see if new cells, organs and tissues are emerging.
    Johnston also omitted to address the origin of the genetic instructions to build new organs, tissues, and body plans.  Could it be as simple as “just add oxygen”? 

At first, these ancient animals were soft-bodied, like modern jellyfish.  Around 542 million years ago, however, some animals developed shells and skeletons and grew larger.
    This was the famous “Cambrian Explosion” of complex life forms, which led to today’s species, the biggest of them another million times larger than their single-celled ancestors.
    Fish, reptiles, birds, amphibians, plants, mammals and human beings were finally on their way, and the Earth’s largest living thing, the sequoia tree, is 10 million billion times bigger than the first tiny microbe in the sea.

Our question about why with so much oxygen the animals waited almost 2 billion years to burst forth with 20 to 40 new complex body plans in a geological instant, without ancestors, is apparently not included in this edition of the story.

If they believe that solves the problem of the origin of genetic information for building new complex body plans, it’s novel, all right – as in science fiction.  Have you ever in your life seen such empty fluff masquerading as an answer?  If you have watched Darwin’s Dilemma, you understand the magnitude of the problem.  At a memorable moment in the film, Richard Sternberg had just discussed the complexity of development of a body plan with its new genes, proteins, cell types, tissues and organs.  “This is orders of magnitude more complex than anything we have been able to conceive,” he said, pointing back over his shoulder.  “You”ve left the idea of ‘impossible by chance’ a long time ago.”  But like a circus ringmaster doubling as a clown and magician, Johnston swept the elephant in the room away with pure magic.  The eukaryote developed [miracle word] skeletons and body plans.  This led to [miracle phrase] the complex Cambrian animals.  Then human beings were finally on their way [miracle phrase].  While you weren’t thinking, his sleight-of-mind trick produced the zoo on stage.  The crowd gasps in awe.  His magic elixir was: oxygen!
    The other team boos from the stands.  No, they shout.  It was calcium!  They come down to the ring and discuss this with the ringmaster.  After some discussion, they come up with a compromise.  They combine the calcium with the oxygen and get CaO2.  Everyone is happy till they realize calcium peroxide is used to sterilize water.
    Get your money back from this circus.  Don’t be one of P.T. Barnum’s suckers, even if The Dawk hawks it as the Greatest Show on Earth.

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Categories: Dumb Ideas, Fossils

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