About Rationally Speaking

Rationally Speaking is a blog maintained by Prof. Massimo Pigliucci, a philosopher at the City University of New York. The blog reflects the Enlightenment figure Marquis de Condorcet's idea of what a public intellectual (yes, we know, that's such a bad word) ought to be: someone who devotes himself to "the tracking down of prejudices in the hiding places where priests, the schools, the government, and all long-established institutions had gathered and protected them." You're welcome. Please notice that the contents of this blog can be reprinted under the standard Creative Commons license.

Monday, May 07, 2007

Yet another nail in the Intelligent Design coffin

The transition from swimming to walking, which happened around 385 million years ago and was one of the pivotal moments in animal evolution, has been somewhat of a mystery for evolutionary biologists, thereby offering the usual (and trite) opening to creationists, seemingly oblivious to the fact that their positions are based on nothing more than an argument from ignorance (often their own).

But as it is often the case in science, new research suddenly throws light on an old mystery. It is what happened recently with the publication of a paper by Auke Ijspeert and colleagues at the Swiss Federal Institute of Technology in Lausanne (Nature, 9 March 2007). The group has built a robotic model of a salamander to test a daring hypothesis about the neurological basis of the switch from swimming to walking that was a necessary part of the evolutionary transition from sea to land.

The researchers focused on a particular neural network, the central pattern generator, that causes rhythmic muscle movement along the body when activated. In lampreys and salamanders this triggers waves of body contractions, causing the animal to swim. The neat piece of the puzzle here is that lampreys (which don't walk on land) only have one such network, while amphibians (which can walk) have a second one in charge of limb movement.

In a previous study, Jean-Marie Cabelguen's group at the University of Bordeaux located the region of the midbrain of salamanders that triggers neuronal firing in both networks, and discovered that the intensity of the stimulation is a direct predictor of the animal's behavior: when the networks are firing at low intensity, the salamander walks; turn up the dial, and it walks faster; turn it even more and some of the nerve cells shut down, the walking stops, and the body begins undulating movements appropriate for swimming!

The group led by Ijspeert then developed a mathematical model of the process, and built a robot, aptly nicknamed Salamandra robotica (see photo), to test it. It worked beautifully, precisely mimicking the behavior of the real thing.

Of course, creationists will entirely miss the point, arguing for example that Salamandra was “intelligently designed” by human beings – thereby displaying a complete misunderstanding of the workings of science (all scientific experiments are “intelligently designed,” but that doesn't mean they can't tell us anything about nature). Alternatively, they will complain that other changes must have happened as well during the time of the transition from sea to land, for example the ability to withstand longer and longer periods away from water. Again, this misses two crucial aspects of evolutionary theory: it does not require that all changes have to happen simultaneously, while it does predict the existence of variation in the characteristics and behaviors of living organism, enough, for example, to insure that some proto-amphibians were better than others at dealing with the stress imposed by the novel environment.

Then again, as we all know, creationism and so-called intelligent design aren't really about reason and evidence. There is no scientific controversy about evolution in the scientific community, there is only people who don't understand science or who put their faith ahead of any possible fact. The funny thing about that, however, is that the same people then turn around and wish to use reason to back up their faith. Could it be that, deep down, they are actually insecure about their simplistic worldview?


  1. Hey, don't forget to italicize the name of the intelligently designed "new species" Salamandra robotica sp. nov.! :O)

  2. Very nice! My only comment is your (mis)use of the word 'animal'

    ...pivotal moments in animal evolution...

    vertebrates represent less than 4% of Animalia, and once the undescribed insects are tallied, probably less than 1%. A change to such a minor proportion of the lineage can hardly be called important to the lineage as a whole (except from a biased human/vertebrate-centric perspective - but scientists should strive to eliminate such bias).

    I'd swap the word animal with 'vertebrate.' And keep on the lookout for similar misuses - they're quite common because children grow up thinking that a vertebrate, like a dog, is a typical "animal" when in fact it's a super-rare very atypical animal (as are all those animals with internal skeletons).

  3. That's true, me (sorry, forgot your name, was it Kevin?). I did sound like "speciesism", or should I say "plylumcism". Yuck.

    But... if you broaden Massimo's sentence a bit and include also non-vertebrates coming out of the water, things would be more fair. It's been seen before how some processes are actually deeply shared (homologous) between beings that didn't look like it was the case. Take for example the development of the eyes. It's not morphologically homologous between insects and vertebrates, but the homeotic gene involved is the same -- to the point that you can swap it between mouse and fly and it still works. Or so I've heard.

    So it might be the case that, even if the limb development does not look homologous between these organisms, it might still be at some deeper level of regulation or the like. We do develop segmentally up to a point after all. So
    the adaptation of the neural network might have been of a similar nature in different organisms. Just speculating, of course. But that might be the case for TWO pivotal moments in animal evolution. :-)

    Unrelated to this all (but nobody would read it in the old post, so here it goes), this nice little text that came out in the Ottawa Citizen, about "Those fanatical atheists".


  4. Not "I did sound", IT did sound...

  5. I had ever wondered for the appear of this novelty.

    I hope creationist people one day learning to be honest with herself. From my perspective it is a matter of have the courage to break some cultural background and to cope the repulse from the others. But, come on guys there is more hope in science and you should recognize (just actually unconscious do) that it is the only way to survive for us.

  6. j
    Thanks for the link to the Canadian article. That rascal pulls no punches!

  7. I think Darwins world view is more simplistic than the creationists.


  8. Aureola Nominee, FCDMay 09, 2007 3:24 PM

    I see, SJ. The classic "I know you are, but what am I?" projection defense.

    There's hardly anything more simplistic than "Goddidit", as is very clearly shown by the failure of any creationist to generate any testable hypothesis about how the world works.

    On the other hand, evolutionary biologists generate, test, and either reject or refine a huge volume of hypotheses, testing them against the ultimate touchstone.

    No, not the Bible.


  9. SJ said...
    I think Darwins world view is more simplistic than the creationists.

    yes, and simplicity is preferred - the principal of parsimony. The creationists posit a number of elements to their explanatory model that are themselves unexplained (and are unexplainable) thereby increasing the complexity of the problem and not solving it at all - just making it worse.

  10. thanks ME thats what i mean when i say more simplistic.

    evolution is like the universal acid of theories. (Daniel C Dennet)

    it burns through all levels of complexity.

    i just think that we shouldnt conceed the 'simplistic' to something that makes no sense on any level.


  11. Aureola Nominee, FCDMay 10, 2007 7:44 AM


    then we shouldn't say it is "simplistic"; it is "simple", but far from "simplistic".

    Anyway, thanks for clarifying what you really meant; on this, I agree.

  12. Yes I take your point Aureola, both ideas are complex in different ways, and can also be over simplified.

    I guess I should have said evolution is more coherent than creationism. Which to me makes it self evidently simple.

  13. put as many nails in the coffin as you want. theres nothing inside.

  14. I'm more interested if any of the IDiots will pick up on the bit of naturally-occuring neural circuitry named the "Central Pattern Generator" - will they cry about the generation of information or the relationship to the second law of thermodynamics (order is being created from disorder!) or some such?

    Nice post, I thought this bit of biorobotics was very interesting.


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