Natural Selection as "Piano Tuning"
At his website Private Papers, Victor Davis Hanson posts a fine review of Jerry Fodor and Massimo Piattelli-Palmarini's What Darwin Got Wrong that gives a really nice, lucid summary of their takedown of natural selection. We're always gratified to discover another conservative, like Hanson, who seems to get it. The author of the review, Terry Scambray, wrote originally in the New Oxford Review:
The most cited example of the power of natural selection is the so-called "Darwin's finches" of the Galapagos Islands whose average beak size fluctuated due to changes in the finches environment. But not only were the changes in the beak sizes of these tiny birds microscopic, but the average beak size returned to normal when the food supply returned to normal and foraging was easy once again even for finches with smaller beaks. In other words, nature, as it usually does, stabilized itself.The piano-tuning metaphor, quite helpful in illuminating the problem of evolution's edge (as Behe puts it), is one we've just put in our back pocket for later use. Read the rest here.
So natural selection in this case did not lead to any progressive and irreversible change of the finches into, say, an eagle or even something closer in its morphology like a robin. Natural selection in this case was a conserving force which occasioned a minor modification, thus permitting the finches to temporarily adapt, then reverse back to their former state so that they could survive intact.
For that matter, the tiny teeter-totter changes of adaptation within a population occur endlessly in nature. Such changes can be something as common as getting a sun tan at the beach which is nature's way of protecting a person's skin; or adaptation happens when a cat sheds its hair in order to adjust to the summer heat.
In other words, organisms will change ever so slightly in order to stay the same and, thus, survive in their particular niche or environment. Besides if an organism were to change too much, as, for example, a fish which by virtue of a mutation acquired nascent legs, the fish would quickly die because it could not survive out of water or, in its helpless state, it would be eaten by predators.
So beyond such adaptations or adjustments, natural selection is incapable of any innovative, irreversible changes in an organism such as a leg changing into a wing, or the scales on a trout changing into the feathers on a thrush. As Fodor and Piattelli-Palmerini concisely put it: "We think of natural selection as tuning the piano, not as composing the melodies."