The Mystery of the Cambrian “Explosion”

ONE of the standard items of propaganda that creationists like to sling around in their ceaseless crusade against reason is that science has no explanation for the so-called Cambrian Explosion. A typical example is this, by Casey Luskin: BioEssays Article Admits “Materialistic Basis of the Cambrian Explosion” is “Elusive”. Here’s another by the same author: Strengths and Weaknesses in David Hillis’s Arguments about the Cambrian Explosion.

The general idea they hope to leave you with is that back in the long-ago Cambrian their supernatural Designer visited earth and performed his mysterious work to magically create a variety of “kinds” which couldn’t possibly have been the result of evolution. That’s their “scientific theory.” But was the “explosion” so incredible that it requires a supernatural explanation?

The Cambrian lasted at least 50 million years. Consider how long that is for purposes of evolutionary change. Let’s say that our own splendid species has been around for roughly 1 million years, and a human generation is 20 years. Okay then:

100 years = 5 generations
1,000 years = 50 generations
10,000 years = 500 generations
100,000 years = 5,000 generations
1 million years = 50,000 generations

That’s a lot of generations during the brief period that we’ve been here. In that short time (geologically speaking), a bewildering variety of dogs have descended from wolves. Galapagos finches change beak sizes within the time frame of human observation (see: Evolution Here, Now, Everywhere). A new breed of tame foxes can appear in only two human generations (see: Domesticated Silver Fox). Peppered moths have changed from white to black and back to white again, all within recent industrial history (see: The Peppered Moth is Turning White Again). What evolutionary changes were possible for us in a span of 50,000 human generations? We’ve found fossils of closely-related species, and although only one human species exists today, we exhibit considerable variation — from pygmies to Danes.

The length of time required for the Cambrian “explosion” was 50 times longer than that, so in human terms it would have been 2.5 million generations. Of course, we’re large animals, and human generations require a long time. Bacteria, in contrast, breed a couple of times each hour. If the typical creature living during the Cambrian required a full year between generations, they had time for 50 million generations. In all likelihood, reproduction in the Cambrian for the simple creatures then alive took much less than a day, possibly only an hour, so there were literally billions of generations during that “explosion.”

Creationists are fond of claiming that Noah’s Ark had plenty of room to contain at least one breeding pair of all land animals on earth. Fine. If they’re that imaginative regarding the capacity of physical space, then they can be similarly generous regarding time. If so, they’ll surely agree that the Cambrian had plenty of time for a whole lot of “micro” evolution to occur; and in a span lasting 50 million years, the cumulative effect of billions of generations was sufficient for all that “micro” evolution to become “macro” evolution.

Will the creationists make that admission? No, because with creationism, integrity is the first casualty. As a fictional character famously said:

“Once you give up integrity, the rest is a piece of cake.”
— J.R. Ewing

However, Arizona State University geologist L. Paul Knauth has been doing a bit of work on the Cambrian. At that university’s website we read this news item: Explosive growth of life on Earth fueled by early greening of planet. Here are a few excerpts, with some bold font added by us for emphasis:

Earth’s 4.5-billion-year history is filled with several turning points when temperatures changed dramatically, asteroids bombarded the planet and life forms came and disappeared. But one of the biggest moments in Earth’s lifetime is the Cambrian explosion of life, roughly 540 million years ago, when complex, multi-cellular life burst out all over the planet.

While scientists can pinpoint this pivotal period as leading to life as we know it today, it is not completely understood what caused the Cambrian explosion of life. Now, researchers led by Arizona State University geologist L. Paul Knauth believe they have found the trigger for the Cambrian explosion.

As you can see, dear reader, Dr. Knauth — here’s his page at the university’s website — is going beyond a mere description of evolution during the Cambrian, and then proclaiming that something magical must have occurred to bring all of this about — he’s suggesting a natural, environmental cause.

Let’s read on:

It was a massive greening of the planet by non-vascular plants, or primitive ground huggers, as Knauth calls them. This period, roughly 700 million years ago virtually set the table for the later explosion of life through the development of early soil that sequestered carbon, led to the build up of oxygen and allowed higher life forms to evolve.

We continue:

“During this period, Earth became extensively occupied by photosynthesizing organisms,” he [Knauth] added. “The greening was a key element in transforming the Precambrian world – which featured low oxygen levels and simple, bacteria dominant life forms – into the kind of world we have today with abundant oxygen and higher forms of plant and animal life.”

There’s more information in the press release. Not only that, but Knauth and his co-author Martin Kennedy, of the University of California, Riverside, will have an article on this in Nature.

It’ll be interesting to see the creationists’ response. There’s sure to be one. Stay tuned to this blog.

Copyright © 2009. The Sensuous Curmudgeon. All rights reserved.

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9 responses to “The Mystery of the Cambrian “Explosion”

  1. The Gadfly

    How can there be a Cambrian Explosion 540 million years ago when the Earth is only 6000 years old.

  2. You’re both wrong. This is Saturday, so the Earth is only 2 days old. 😉

    Seriously, most DI folk will admit that the Cambrian “explosion” was 540 MY ago. But they try not to advertise it.

  3. OK, I can’t get the day of the week right, so I must be wrong about evolution, and YECs and OECs are both right. 😉

  4. Frank J says: “This is Saturday …”

    Hee hee!

  5. At the Texas science standards public hearings, Stephen Meyer seemed to think the Cambrian Explosion lasted around 5 million years. The priceless reaction from Steve Schafersman:

    Meyer defended his description of the Cambrian Explosion as a weakness of evolution. He castigated the idea that the increase in atmospheric oxygen content increased the biological information necessary for all the new phyla and other taxa to appear so quickly. He also said that Dr. Hillis’s statement that the Cambrian Explosion had tens of millions of years to occur is wrong. Instead, Meyer said, the most recent research says that the Cambrian Explosion took place in about five million years, and certainly no more than ten million. I am an evolutionary paleontologist and stratigrapher, and I can say without qualification that Stephen Meyer is totally and completely wrong. He really doesn’t know what he’s talking about, and he characterizes himself as an expert in paleontology and geology. His incompetence and lack of knowledge–or willingness to deceive–is simply spectacular.

  6. James F says:

    At the Texas science standards public hearings, Stephen Meyer seemed to think the Cambrian Explosion lasted around 5 million years.

    I’m shocked. Shocked!

  7. retiredsciguy

    Another thing to consider — multicellular life forms didn’t first appear at the beginning of the Cambrian; they just started fossilizing well at that time. The Late Precambrian has evidence of jellyfish, worms, and other soft-tissued multicellular life going back to at least one billion years ago. Problem is, being soft-tissued, we don’t have much of a record today.
    The Cambrian Explosion was really the evolutionary introduction of hard shells, presumably as protection against predators.

  8. I have to agree with the creationists, 6000 years just isn’t long enough.

    Hey, they just have to start off with a different set of assumptions than us to get where they really want to be.