Wednesday, February 24, 2010

The Conservative Nature of Natural Selection

In the class on the History and Philosophy of Atheism I'm taking this semester at Kilns College, I had the opportunity last night to guest-lecture on naturalism and evolution. I mentioned that we now know--150 years after Darwin--that the mechanism of natural selection that he endowed with incredible creative potential instead acts only in conservative and degenerative ways. Time, however, prevented me from sharing one of my favorite illustrations of this, the "green toothpick" illustration. So I'll share it here.

I took an undergraduate biology class from Dr. M.D. "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), continued natural selection (predation on those toothpicks most easily spotted) would eventually cause those toothpicks to 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.)


Jordan said...

OK, hopefully my woeful lack of biology training (I did take a genetics class but that was a loooong time ago) won't be too obvious here.

My understanding was that mutations provided the fodder for natural selection to add new genetic information (toothpicks). That is, the toothpick colors shouldn't be static I guess but new random colors should show up.

The other thing I'm wondering about is that there seems to be quite a bit of talk about how natural selection might not be the big evolutionary driving force everybody used to think it was. Perhaps stuff like gene flow and genetic drift counteract the conservative nature of natural selection?

Anyway, those are just some "devil's advocate" question I've been wondering about. For sure I've always been puzzled about natural selection when it seems like if anything, it gets rid of genetic material, not increase it.

Rick Gerhardt said...


You're absolutely right. The current understanding--neo-Darwinism or the "Modern Synthesis"--involves two things. These are natural selection acting upon random genetic mutations. And the whole story is that neither of these has creative ability. The point of my most recent post was to demonstrate (by using the best illustration that my evolutionary biology professor could come up with) the failure of the former, natural selection.

If you can see that NS has no creative potential of its own, then my argument is half finished. It will be rather simple to demonstrate (in a later post) that mutations likewise have no creative power. But before moving on to that, let me make it clear that evolutionists--like Richard Dawkins--really do imbue NS with God-like creative power, and remain blissfully unaware that in 150 years of research since Darwin we have found no evidence that NS can do anything but keep individuals of a species from varying too far from that species' mean.

Your second point (your third paragraph) seemed to allude to a questioning of the power of NS from within the biological community. Again, you're absolutely correct. There are increasingly frequent and vocal calls from within biology for a new (or "Third") synthesis, which represents a tacit acknowledgment that neo-Darwinism is a failure. Last month, for example, geneticist James Shapiro told a packed auditorium at the University of Chicago that "Richard Dawkins is a man who lives in a fantasy world." Nonetheless, in the popular media, Natural Selection still remains as religious dogma, and the proponents of this inadequate theory still control the microphone.

Moreover, those calling for a new synthesis do not go far enough. They continue to assume a naturalist/materialist view of the world, despite two important facts... 1) It was Darwin's now-refuted natural selection that caused biologists to adopt a naturalistic approach to science in the first place, and 2) astronomy and physics have now demonstrated both that the universe had a transcendent beginning (powerfully supporting the cosmology of Christian theism and refuting the cosmology under which evolutionary theory and naturalism were proposed) and that the universe is itself designed with the goal of supporting intelligent life on Earth.

It's a good time to be a theist, as God is providing our skeptical generation with powerful evidence for His existence and love. But many scientists, unaware of the relevant philosophical issues, will continue to cling to naturalistic theories about life's history, even though all the evidence and reason argue against such a view.

Thanks for your perceptive comments.

Debi said...

Ok, my question revolves around moths. Based on your post and the toothpick model if there were purple, yellow, grey and red moths flying around and a power plant came in and they had to all adapt to the changed environment, then the grey ones might survive and add some spots or the like to fit in with the environment of pollution.

But if they power plant was shut down and they put in wind turbines they grey spotted ones would not be able to turn white because they have no creative potential and the larger gene pool was already so watered down.

Right? or it could but it couldn't turn into a different animal all together because that would be more practical for that environment.

Just trying to wrap my little mind around all this.