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
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?