12 September 2008

The Last Simple Machine

Why do people have such a difficult time believing in the hand of God at work in the natural world? Talk to a hard-core empiricist about how and why God might have designed the world, and you'll often get the same argument: "Nothing exists that can't be adequately explained by purely mechanistic, natural processes." Of course, what they are asserting is the opposite but no more logically valid than saying, "Nothing exists that can't be adequately explained by purely non-mechanistic, super-natural processes." If you point this out, though, you usually lose them in a debate about why the answer to the logic question should default to their explanation, and not to yours. People often treat their foundational assumptions as if they've already been logically established somewhere else. We all do that. It's how we think.

But I prefer the supernatural world view, and one aspect of it keeps coming to my mind, of late. There's something that I have always found fascinating about man-made machine analogs to the bodies of living organisms in the natural world. I see the hand of God in these analogs, where divinely-created nature and human-assembled culture blur together, and the two seem to blend into a larger and more coherent singularity. I remember back in grade school learning about the simple machines of classical Greek mechanics--the lever, the screw, the wheel and axle, the rope and pulley, the wedge, the inclined plane. You can take any mechanism that we might build today, and reduce it to various assemblies of those simple machines. And I used to wrinkle my forehead about all the simple machines that could be found in human culture, and how all of them were found in nature first. The wedges in my incisor teeth help me bite into an apple. The screw-shaped hull of an oat seed forces it into the ground with changes in the weather. Levers help a tendon extend my knee, or turn the pages of a book, and so on. Even a rope and pulley arrangement wiggles my fingers and toes, just without a rotating structure. There was only one exception: the wheel and axle. The wheel and axle was completely absent from the non-human world. I could find all the others. But where was this one? No place, it seemed. No spider's leg, no insect muscle, no bat's wing, no salmon's tail, nothing. Nothing in the natural world, it seemed, was built to use a wheel and axle.

Then one day I was reading a book called Darwin's Black Box--The Biochemical Challenge to Evolution, written by a molecular biologist from Pennsylvania. In it, Michael Behe proposed a new way to think about the smallest molecular pathways of organic evolution, which he proposed required something he called "intelligent design." Intelligent design is a loaded term today among those people eager to fight various social battles in public education. Sadly, over many years I have watched supporters for both sides of the question misrepresent the truth in their eagerness to control social policy. But Behe's original little book didn't concern itself with that. Like many professional scientists, he was interested in the idea for its own sake. What stopped me cold with his book in my hands was one of his examples. It was the complex molecular structure that made the little tails spin on the back ends of single-celled organisms--the flagella-- to shoot them through the water on their microscopic errands, whatever they might be. The structure was a tiny electric motor, where the flagellum began as a tiny knob held inside a tiny socket on the tiny body of the organism. Chemical changes caused electric charges to repel and attract each other between molecular structures on the knob and the socket, and made the flagellum spin. This in turn pushed the little creature through the water. Exactly like the little propeller shaft on a battery-powered toy boat, or the drive wheels of a model car. The flagellum and its socket were a little wheel and axle. It was the last Simple Machine.

Behe used this structure as one of several examples of his theory of irreducible complexity, in which he said you reconstruct the evolution of a structure by following the path of natural selection back to the earliest, theoretically simplest form. Earlier than that point, he said, the pieces don't work together, and something else has to be suggested for bringing them together correctly for natural selection to get started. This is old stuff (Charles Darwin himself famously wondered about the origin of a functioning eye), but Behe's use of basic and fundamental examples from microbiology raised a lot of interest when he published his book. His example of the flagellum seemed to show that the molecular pieces making up the little motor wouldn't function at all in a simpler arrangement, and the simplest arrangement that did work was far too complex to have arisen through any realistic mutational pathway. So ordinary natural selection couldn't build it from scratch, and various other molecular structures and processes had similar problems, at that scale. A fascinating topic if you read the original discussion, rather than taking other people's words for what it's all about. There's been a lot of distortion of his idea by others since then, on both sides of the evolution argument, but I haven't personally read of that example of the little spinning tail being explained away. Explainable or not, though, it was the last Simple Machine.

And this is where I continue to marvel at a natural world which to me is clearly an expression of the mind and handiwork of a Creator. To me, the hand of the designer is apparent everywhere, from wings, to cilia, to the citric acid cycle, or the main sequence of stellar evolution. And as there isn't anything that can't be adequately explained by purely non-mechanistic, supernatural causes, I don't need to invoke purely natural mechanistic causes to explain quantum physics, or the Big Bang, or barnacle diversity in a coral reef. The hand of a Creator is a simple enough answer for me, and I choose the piece falling from Occam's Razor that reflects the face of God.

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