National Geographic

Rising Seas, Burrowing Worms, and Nasty Jaws: Weaving Together Animal Evolution

Just over half a billion years ago, the animal kingdom went through a remarkable flowering that lasted somewhere in the neighborhood of 20 million years. During the so-called Cambrian Explosion, the first known fossils of many major groups of living animals appear. It’s a chapter of evolutionary history that has captivated many scientists ever since Darwin. And in recent years researchers have gathered a lot of fresh evidence about different factors that might have been the trigger to this evolutionary big boom. Today in the New York Times, I talk to Paul Martin, the director of the Oxford Museum of Natural History, who has co-authored a new synthesis of ideas about the Cambrian Explosion. Rather than looking for just one cause–such as rising sea levels–he argues for a tangled web of feedback loops. Check it out.

There are 2 Comments. Add Yours.

  1. James V. Kohl
    September 19, 2013

    In my model, the feedback loops are nutrient-dependent and pheromone-controlled. In this article, it seems like you’re moving away from any theory that involves mutation-driven evolution.

    Do you think that the preservation of docosahexaenoic acid (DHA) “… in neural signalling systems for 500–600 million years… despite enormous genomic changes since the beginning of animal evolution” is an important consideration? If not, can evolutionary theorists ignore it like they ignore the fact that no evidence suggests mutations are fixed in the DNA of the organized genome in any species from microbes to man?

  2. Thomas R. Holtz, Jr.
    September 20, 2013

    Dear J.V. Kohl,

    Keep in mind that mutations need not be “fixed” by any special mechanism over huge swaths of the Tree of Life and yet unvaried over the same. If an ultracritical trait were mutated into a fashion that wasn’t operational, that embryo would not form completely, and thus won’t have descendants. Critical failures cannot be passed on.

    Only mutations that can actually survive get passed on; all others automatically get filtered out (and most long before birth/hatching).

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