• Weaknesses of Evolution – Part 6 – The Cambrian Explosion

    With this part of our exploration of the ‘weaknesses of evolution‘ we move from origins of life into the fossil record. Fossils present an insurmountable problem for creationists.  These are clearly organisms that no longer exist.  Fossils show a steady change over geologic time.  The older the fossil, the more unlike modern organisms it is.

    The website I’m refuting here has some very specific claims for fossils, which I like.  It’s much easier to refute or explain specific claims rather than vague, ill-defined claims (as we saw in part 5).

    The Cambrian explosion quickly produced all of the basically different body structures, and some of these have since become extinct. This is very different from the evolutionary tree of life, which suggests a slow and gradual increase in body structures.

    Ah, the Cambrian Explosion.  Another classic.  I love this line “quickly produced”.

    The Cambrian explosion refers to a increase in the rate of evolution that occurred during the Cambrian period of Earth’s history.  The Cambrian and the ‘explosion’ are dated between 540 mya (million years ago) and 495 mya.  So, this “quick” event lasted for about 60-70 million years.  That’s about 70 times as long as modern humans have been in existence.

    The fossil record as Darwin knew it (and up into the 1980s) supported the idea that the major groups of metazoans (animals) appeared during this time frame.  However, we now know that many body plans, phyla, ways of life, etc. that we thought first appeared in Cambrian actually appeared earlier.  Bilateral creatures appeared before the Cambrian. Cnidarians (jellies and corals) appeared before the Cambrian. Predators appeared in the Precambrian and almost a billion years before the Cambrian.

    Indeed, the modern research shows that the amount of evolution and adaptation in the Cambrian ‘explosion’ is no faster than any other of the radiations in the history of animal life.

    There are some innovations that appeared in the Cambrian.  Armor appears in the Cambrian.  But then, intelligence only appears in the in Quaternary.  Of course, flowering plants (which have taken over the world) first appeared in the Jurassic.  So, it’s not like innovation is something that has never happened before.

    So that pretty much refutes the claim of the creationists anyway.  However, there’s another point here and it’s related to the next creationist claim.

    Many life forms persist through large expanses of geologic time with essentially no change.  Evolution theory suggests that mutations occur randomly over time and are selected to produce continuing change as the environment continually changes.

    Even if there was a massive increase in evolution in the Cambrian.  So what?

    Evolution doesn’t actually suggest a slow and steady change over time.  There’s the hypothesis that was promoted by Stephen J. Gould and Ernst Mayr called punctuated equalibria. It basically states that populations of organisms may remain fairly static until there is an external change that causes massive adaptation.  For example, the evolution of citrate consuming bacteria.  (I keep referring back to the same examples for sake of brevity, but there are plenty of others.)

    Further, with the more recent understanding of evolutionary developmental biology, there is no reason to suspect a slow and gradual change anyway.  A single change in a single regulatory gene that controls development can result in massive changes in the organism’s morphology.  A single change can result in an inset with 4 or 5 body segments instead of three.  It can result in legs replacing antennae or eyes growing on knee joints.

    This link has some excellent examples of how changes to regulatory genes change the organism.

    Even if the Cambrian period had a much higher rate of evolution than ‘normal’, so what?  Evolution as a theory doesn’t specify a rate of change.  And modern science has discovered that such rapid changes are completely possible.

    Another point is about climate change here.  Yes, adaptations would occur as the climate changed.  But climate changes are generally on a nearly geologic time scale.  Even with the rapid climate change caused by man, we’re talking a couple of degrees change in temperature per 100 years.  For most organisms, that’s 50 or more generations. We just can’t resolve that narrow period of time, especially back in the Cambrian.

    If we consider a change that took 1,000 years in the Canbrian 70,000,000 years we’re talking about trying to see changes that occurred in 0.000014% of the time within the Cambrian.  The limits of fossilization just don’t allow for that.  We just can’t know if the temperature when fossil x died was y.  We can see massive upheavals in the environment such as the change from an ocean to a beach to a prairie.  That’s a much more significant change (that takes longer) than just climate change.

    Is climate change important to evolution?  Sure.  But we can’t resolve the issues at that level of detail.

    This claim by creationists is not only wrong, but it wouldn’t matter even if it was true.


    Category: CreationismEvolutionScienceSkepticism


    Article by: Smilodon's Retreat