The Good News: As a professor of biochemistry, what made you question Darwin's theory of evolution?

Michael Behe: I used to believe in Darwin's theory because I was taught it in high school and college. I'm now a biochemist, and when you study biochemistry you study very complicated molecular systems that are the basis of the cell and the foundation of life. Many times I would wonder how something that complicated could have evolved by a step-by-step Darwinian process. But I tried to shrug off the doubts.

GN: What happened then?

MB: In the late 1980s, when I was an associate professor of biochemistry, I read the book Evolution: A Theory in Crisis by a geneticist, Michael Denton. And in it, Denton presented a number of arguments against the Darwinian theory that I thought were good arguments and that I had never heard of before. I became angry because here I was a professor of science at a leading university and had never heard these criticisms, let alone how to answer them. I became angry because I had been led to believe in the Darwinian theory, not because the evidence was compelling, but because that's what I was expected to believe.

GN: What did you do?

MB: After reading Denton's book, I decided to go to the science library and look at the science journals to see who had explained the complicated cellular systems by a Darwinian process. I was astounded to find there were no published papers, or none to speak of, that even tried to explain how a step-by-step process could produce such complexity. At that point I figured a new idea was needed and so I started to think more about alternatives.

GN: You often speak of "molecular machines." In the molecular world, are all structures of life made up of molecular machines?

MB: Many things in the cells are molecular machines. Quite literally they are machines made of molecules—that is, they have gears, screws and bolts. There are things like little molecular trucks that will walk along highways and there are little traffic signs and so on.

But not everything in the cell is a machine. Some things are fuel—they fuel the machines. There are things like bricks and cement that hold structures together. I wouldn't call these machines. They are part of the building itself. But the interesting part of the cell is it's really an elegant machine.

GN: What are some of your favorite examples of these molecular machines?

MB: My favorite examples are those that remind us of the machines in our everyday world. Perhaps my all-time favorite is the bacterial flagellum, which is quite literally an outboard motor that bacteria use to swim. It's just like putting an outboard motor on a boat to go through the water. Instead of using gasoline, it uses a flow of acid from one side of the cell to the other.

There are nuts and bolts that hold the pieces together, and a hook region that is actually a universal joint allowing the drive shaft and the propeller to turn. There is an anchor called a stater, which holds the structure onto the cell wall and allows it to stay in place while the propeller turns.

When I show the picture of this structure, people ask if this is a machine NASA designed or if it comes from an engineering journal. When I tell them it's a biological structure found in the cell, they quickly grasp that these things do not look like they were put together by random Darwinian processes—rather that they were designed.

GN: What is another striking example?

MB: The network for moving supplies from one side of the cell to another. Things have to be carried and put on little molecular trucks. They have to know what direction to take, their destination, when to get there and what to load, much like UPS or FedEx does. There are literally trucks and highways and signs and many other things necessary for things to work.

GN: Are Darwin's ideas bad science?

MB: It depends on what you mean by bad science. Good ideas and promising ideas are good science, even if they turn out to be wrong in the end—but they are good science nonetheless. I think Darwin's idea was a good idea. It looked like it might have a chance when he proposed it. But even when he proposed it in 1859 there were problems with it, as he admitted.

The assumption when he published his idea was that the foundation of life was simple. Cells were simple little things like jelly and protoplasm. Maybe as he knew more and more about this simpler foundation of life, he would see how the simplicity would give rise to the complexity that we saw in organisms such as legs, eyes and ears.

It was a good idea, but it turned out to be incorrect. As science progressed and we learned more about life, we saw inexorably that it was not complexity at the top and simplicity underneath, but it was complexity at the top, and more complexity underneath.

We learned the cell is not a simple blob of jelly. It has these molecular machines in it. It has a sophisticated mechanism that man has not been able to reproduce. And much of it is what I call irreducibly complex, so that if you take one part away from the machine, the machine will break down, just as you can take a couple of spark plugs from a car and it will not work. Things will break down in the cell as well.

These things haven't been explained by Darwinian theory in any journal article, and there's good reason to think that, in principle, they can't be explained by Darwinian theory.

So Darwin's idea, now viewed in retrospect, has a much more limited range of application. Darwinian evolution can really explain when an organism has a slight change that might favor it—natural selection can explain that. For example, how a polar bear might have arisen from a brown bear. It can explain insecticide resistance in insects and so on. So it can explain little changes, but it's the big things in life that it has trouble explaining.

GN: What do you mean when you say something is irreducibly complex, and how does that fit with Darwinian evolution?

MB: It sounds like a fancy word, but it is really a simple idea. It means you have a machine or some organization or system that has a number of different components that act on one another or push against each other. The result is that they perform some action that the parts themselves couldn't do, and if you take one of the parts away the system breaks down because you need all the parts for it to work.

An example is a mousetrap. Usually it has a wooden base, a spring, a hammer, an arm and a catch. If you take one of the parts out, it doesn't work and you can't catch mice.

It is very hard to see how you could fit something like this mousetrap in a step-by-step process, where each step does a job and improves the system. And that's the way Darwinian evolution has to work. It has to work by having some system that is already functioning, and natural selection trying to improve it slowly into a better system.

But with a mousetrap, if you started with a wooden platform, that wouldn't catch any mice. Natural selection would have no reason to keep that. Even if you put another component on it, it still wouldn't catch mice. The important thing about irreducible complexity is there are many systems in the cell that have that same property. You take one component away and it's broken; it doesn't work any more.

So that's a big problem for Darwinian evolution because you can't put things like that together gradually. It seems you need intelligence or some other outside intelligent agency to put these things together.

GN: What are the main ideas behind the "intelligent design" movement?

MB: The basic idea is that by looking at features from natural systems, you can discern an intelligent agent was involved in setting up the system. A good example in the U.S. is a mountain called Mt. Rushmore.

On the face of this mountain have been carved the faces of four American presidents. If you were from another country and never heard of Mt. Rushmore, and were driving down the road when suddenly you see these faces on the mountain, you would know they were not formed by erosion, wind or any other unintelligent sources. You would know a mind was involved, some culture was out there and made that.

The same idea applies in any area of nature. Suppose you're an astronomer and you're studying the radio waves that fill the universe. Most of them are static, but you have your antennae focused, and all of a sudden you hear radio waves that are conveying a message—something like "We would like pizza, too" or "Greetings from Alpha Centauri"—then it would be dumb to ascribe those to random physical forces. You would ascribe them to intelligent space aliens.

Now if you are a biologist and you think the cell is a glob of protoplasm but you go on to investigate it and you find out that instead of being simple, it is filled with these elegant machines—machines of greater sophistication than we are capable of making—that is telling us something.

The intelligent design hypothesis says we can infer that a mind was at work there, too—that matter and energy and natural processes are not sufficient to explain how the cell came to be arranged that way.

GN: Is the information embedded in DNA matter, energy or something else?

MB: That's an excellent question. This harkens back to the 1960s when a physical chemist made the point explicitly that information is not matter or energy but something else. He talked about a paper with writing on it. He said the chemistry of the ink and the paper is well understood, but you cannot explain the message on the paper in terms of the physical properties of either the ink or the paper.

In the same way, we found information in the DNA, and the information is not in the chemical or the physical properties of DNA. It's the way the pieces of DNA, called nucleotides, are arranged in a string. Just as a string of letters in a word, a sentence or a paragraph, these give sensible information that tell the cell how to make itself.

So in the intelligent design theory, since we take it as a given that there is such a thing as intelligence, information is not matter or energy. We say, yes, there is something else in DNA, and that is the intelligence component.

GN: What do you think the situation will be like in the year 2025 for the intelligent design movement and Darwinian evolution?

MB: In the year 2025 what we view as the complexity of the genome in the cell today will be seen as child's play compared to the complexity we will have discovered in the next 20 years. As we discover more about the cell, at every turn we find it is far more sophisticated, more elegant and more complicated than we ever thought, and that trend is not decreasing.

So the things I write about that show intelligent design will look like child's play compared to what we will discover. I think the case for intelligent design will be even stronger. The problem, though, is more political than scientific. The scientific argument is easy to see, but some people have committed themselves to materialism. For intelligent design to make strong inroads into science, that will have to change.

One way things can be changed is if students and young scientists more open to intelligent design begin to choose scientific careers and make their views known. Then if a critical mass of people say they are open to the idea of intelligent design, I think Darwinism will indeed collapse.

Right now it is being held up simply by social pressure among scientists who view the world in a certain way. But if a significant group of scientists dissents from that view, then Darwinism will have to prove its case—and I don't think it can prove it. GN