Thursday, November 20, 2008

Green Toothpicks

In the class I'm teaching this semester at Kilns College, I had the opportunity last night to address naturalism and evolution. Among the many illustrations this allowed me to resurrect, one of my favorites has to do with green toothpicks.

I took an undergraduate biology class from Dr. "Mad Dog" Johnson, in which he tried to demonstrate natural selection in action. We went outside to a lush, uncut, well-fertilized portion of the campus lawn, where we scattered a known number of toothpicks of different colors--red, yellow, blue, and green. We, the students, then acted as predators--the agents of natural selection--foraging through that patch of lawn capturing as many toothpicks as we could find. As I recall, we found all of the yellow and red toothpicks, most of the blue ones, and almost none of the green, so well-camouflaged were they among the long blades of grass. The lesson was that natural selection works just so on populations of living things.

There are at least a couple of serious problems with this experiment as an illustration of natural selection at work. If--as is claimed--natural selection acting on genetic variation is the mechanism by which evolutionary advance is made, what we demonstrated would seem to be just the opposite. Our toothpick population began with a much higher genetic diversity than it had by the end. The population, which now consists almost entirely of green toothpicks, would seem to be much less able to adapt to a changing environment than when it contained the greater diversity of phenotypes. It has ever since seemed to me that we demonstrated that natural selection has a far greater capacity to tend toward extinction than to adaptation and advance.

Another problem with this illustration is just as important. Let us be unreasonably generous and grant that the resulting population of toothpicks is somehow better prepared to adapt to some future environmental change. That is, let us say--for the sake of argument--that what we witnessed was an instance of microevolution. Microevolution refers to the idea that species (and populations and such) are not static, but change over time in both their phenotype and genotype (their form and the genetic basis for that form, respectively).

That microevolution occurs is a well-accepted, non-controversial idea. But granting that the population of green toothpicks is a good example of something having undergone microevolution provides no support for the claim of neo-Darwinism, which is that this same mechanism--natural selection acting upon genetic variation (mutation)--can account for macroevolution. In other words, the diversity of all life is explainable by this sort of natural selection acting over vast time scales. In the specific case of the toothpick illustration, we are to believe that if we waited long enough (as the toothpicks bred generation after generation) and continued preying on those toothpicks most easily spotted, eventually those toothpicks would give rise to species of dental floss, of toothbrushes, and even, eventually, of electric toothbrushes, all without the input of any sort of intelligence or designer.

The fossil record shows that there have existed--over the course of Earth's history--different life forms. But macroevolutionary theory, as an explanation for how that record came to be, has yet to be substantiated by any evidence. Rare cases of microevolution have been documented, and then we are asked to make the unreasonable and unsupported extrapolation that such minor changes can be invoked to explain all of the advancing complexity witnessed in the fossil record. For me, Professor Johnson's toothpick demonstration has always served as a reminder of the absurdity of the grander claims of evolutionists.

(A version of this post originally appeared on 26 Feb 2007.)

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