We have always underestimated the cell.... The entire cell can be viewed as a factory that contains an elaborate network of interlocking assembly lines, each of which is composed of a set of large protein machines.... Why do we call [them] machines? Precisely because, like machines invented by humans to deal efficiently with the macroscopic world, these protein assemblies contain highly coordinated moving parts.
Bruce Alberts, President, National Academy of Sciences
We should reject, as a matter of principle, the substitution of intelligent design for the dialogue of chance and necessity; but we must concede that there are presently no detailed Darwinian accounts of the evolution of any biochemical system, only a variety of wishful speculations.
Biochemist Franklin M. Harold
Michael Behe was taught in parochial school that God had set up the universe, knew what was going to happen, and intended for life to come into existence, but from our perspective the entire process unfolded through Darwinian evolution. And that pretty much satisfied the young Behe.
Later as a student in biochemistry, when Behe would encounter enormously complicated biological systems, his response was to scratch his head and say, "Gee, I wonder how evolution created that? Well, somebody must know!" He always moved on, assuming someone did.
Then one day, while doing post-doctorate research on DNA at the National Institutes of Health, he and a colleague were pondering what it would take for life to begin by naturalistic processes. As they enumerated the components that would be needed-proteins, a genetic code, a membrane, and so on-they looked at each other and said, "Naaaaahhhhhh!" They knew there was no way life could have sprung into existence unaided. Seeds of skepticism were planted.
Subsequently, he read geneticist Michael Denton's groundbreaking book Evolution: A Theory in Crisis.
Until then, he only knew of "religious nuts" who doubted Darwin. Now, here was a thoughtful, agnostic scientist who was powerfully challenging whether Darwin's mechanism of natural selection could really explain how life started and developed through the ages.
Spurred on by Denton's book, Behe began scouring the scientific literature in search of the detailed Darwinian explanations he had always assumed were there. Time after time, he found scientists describing complex, interlocking biological systems and basically saying, "Isn't it wonderful how natural selection put this together?" The how was always missing.
That's when Behe realized that as a biochemist, he was perfectly situated to investigate whether the evidence points toward Darwinism or God as the source for living organisms. After all, life is essentially a molecular phenomenon. If Darwinian evolution is going to work, it has to succeed at the microscopic level of amino acids, proteins, and DNA. On the other hand, if there really was a designer of the world, then his fingerprints were going to be all over the cell.
And the cell is Behe's world-an incredible, intricate, Lilliputian world where a typical cell takes ten million million atoms to build. One scientist described a single-cell organism as a high-tech factory, complete with
artificial languages and their decoding systems, memory banks for information storage and retrieval, elegant control systems regulating the automated assembly of parts and components, error fail-safe and proof-reading devices utilized for quality control, assembly processes involving the principle of prefabrication and modular construction ... [and] a capacity not equaled in any of our own most advanced machines, for it would be capable of replicating its entire structure within a matter of a few hours.
Shaking off his preconceptions as best he could, Behe began to scrutinize the molecular evidence with new eyes. Ultimately, he would summarize his stunning conclusions in what the National Review would call one of the most important non-fiction books of the twentieth century.
INTERVIEW #6: MICHAEL J. BEHE, PHD
Behe credits his casual manner to being the father of eight (at the time, going on nine) children, who keep him from taking himself too seriously. He laughed when I asked if he had any hobbies. "Mostly, I drive kids places," he said.
Behe grew up on the other side of Pennsylvania. He received a degree in chemistry with honors from Drexel University and a doctorate in biochemistry at the University of Pennsylvania. After post-doctorate research at the University of Pennsylvania and the National Institutes of Health, he joined Lehigh's faculty in 1985. He also has served on the Molecular Biochemistry Review Panel of the Division of Molecular and Cellular Biosciences at the National Science Foundation.
He has authored forty articles for such scientific journals as DNA Sequence, The Journal of Molecular Biology, Nucleic Acids Research, Biopolymers, Proceedings of the National Academy of Sciences USA, Biophysics, and Biochemistry. He has lectured at the Mayo Clinic and dozens of schools, including Yale, Carnegie-Mellon, the University of Aberdeen, Temple, Colgate, Notre Dame, and Princeton. He is a member of the American Society for Biochemistry and Molecular Biology, the Society for Molecular Biology and Evolution, and other professional organizations.
Behe has contributed to several books, including Mere Creation, Signs of Intelligence, and Creation and Evolution. He was catapulted into the national spotlight, however, by his enigmatically titled and award-winning best-seller, Darwin's Black Box. According to David Berlinski, author of A Tour of the Calculus, Behe's book "makes an overwhelming case against Darwin on the biochemical level" through an argument "of great originality, elegance, and intellectual power." Added Berlinski: "No one has done this before."4
In fact, it was this book that lured me to Lehigh. I knew that Behe's theories could provide strong support for the idea that a designer created the tiny but complex molecular machines that drive the cellular world-that is, if his arguments could withstand the objections of skeptical Darwinists.
PEERING INSIDE THE BLACK BOX
The "black box" in the title of Behe's book is a term scientists use when describing a system or machine that they find interesting but they don't know how it works. As an example, Behe gestured toward the Dell computer on his desk. "A computer is a black box for most people," he explained. "You type on the keyboard and you can do word processing or play electronic games, but most of us don't have the foggiest idea of how the computer actually works."
"And to Darwin, the cell was a black box," I commented.
"That's right," he replied. "In Darwin's day, scientists could see the cell under a microscope, but it looked like a little glob of Jello, with a dark spot as the nucleus. The cell could do interesting thingsit could divide, it could move around-but they didn't know how it did anything."
"There must have been speculation," I said.
"Of course," Behe said. "Electricity was a big deal back then, and some believed that all you had to do was to zap some gelatinous material and it would come alive. Most scientists speculated that the deeper they delved into the cell, the more simplicity they would find. But the opposite happened.
"Now we've probed to the bottom of life, so to speak-we're at the level of molecules-and there's complexity all the way down. We've learned the cell is horrendously complicated, and that it's actually run by micromachines of the right shape, the right strength, and the right interactions. The existence of these machines challenges a test that Darwin himself provided."
"Darwin said in his Origin of Species, `If it could be demonstrated that any complex organ existed which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down.'' And that was the basis for my concept of irreducible complexity.
"You see, a system or device is irreducibly complex if it has a number of different components that all work together to accomplish the task of the system, and if you were to remove one of the components, the system would no longer function. An irreducibly complex system is highly unlikely to be built piece-by-piece through Darwinian processes, because the system has to be fully present in order for it to function.
The illustration I like to use is a mousetrap."
I chuckled. "Do you have problems with mice at your house?"
"Actually, yes, we do," he said with a laugh. "But a mousetrap has turned out to be a great example."
He stood and walked over to a filing cabinet, removing a run-of-the-mill mousetrap and putting it down on the desk next to me. "You can see the interdependence of the parts for yourself," he said, pointing to each component as he described them.
"First, there's a flat wooden platform to which the other parts are attached. Second, there's a metal hammer, which does the job of crushing the mouse. Third, there's a spring with extended ends to press against the platform and the hammer when the trap is charged. Fourth, there's a catch that releases when a mouse applies a slight bit of pressure. And, fifth, there's a metal bar that connects to the catch and holds the hammer back when the trap is charged.
"Now, if you take away any of these parts-the spring or the holding bar or whatever-then it's not like the mousetrap becomes half as efficient as it used to be or it only catches half as many mice. Instead, it doesn't catch any mice. It's broken. It doesn't work at all."
He pointed down at the trap again. "And notice that you don't just need to have these five parts, but they also have to be matched to each other and have the right spatial relationship to each other. See-the parts are stapled in the right place. An intelligent agent does that for a mousetrap. But in the cell, who tells the parts where they should go? Who staples them together? Nobody-they have to do it on their own. You have to have the information resident in the system to tell the components to get together in the right orientation, otherwise it's useless."
Behe sat back down. "So the mousetrap does a good job of illustrating how irreducibly complex biological systems defy a Darwinian explanation," he continued.
"Evolution can't produce an irreducibly complex biological machine suddenly, all at once, because it's much too complicated. The odds against that would be prohibitive. And you can't produce it directly by numerous, successive, slight modifications of a precursor system, because any precursor system would be missing a part and consequently couldn't function. There would be no reason for it to exist. And natural selection chooses systems that are already working."
I studied the mousetrap. "You said an irreducibly complex system can't be produced directly by numerous, successive, slight modifications," I said. "Does that mean there couldn't be an indirect route?" Behe shook his head. "You can't absolutely rule out all theoretical possibilities of a gradual, circuitous route," he said. "But the more complex the interacting system, the far less likely an indirect route can account for it. And as we discover more and more of these irreducibly complex biological systems, we can be more and more confident that we've met Darwin's criterion of failure."
I asked, "Are there a lot of different kinds of biological machines at the cellular level?"
"Life is actually based on molecular machines," he replied. "They haul cargo from one place in the cell to another; they turn cellular switches on and off; they act as pulleys and cables; electrical machines let current flow through nerves; manufacturing machines build other machines; solar-powered machines capture the energy from light and store it in chemicals. Molecular machinery lets cells move, reproduce, and process food. In fact, every part of the cell's function is controlled by complex, highly calibrated machines."
Behe motioned toward the mousetrap. "And if the creation of a simple device like this requires intelligent design," he said, "then we have to ask, `What about the finely tuned machines of the cellular world?' If evolution can't adequately explain them, then scientists should be free to consider other alternatives."
Before I began investigating that issue any further, though, I wanted to stay focused a while longer on Behe's whimsical use of the mousetrap to illustrate irreducible complexity. Ever since Darwin's Black Box was published, the lowly rodent-catcher has become something of a new icon in the debate over evolution versus design. As such, it has been pelted by opposition from Darwinists-and I needed to know if Behe could fend off the best challenges.
MESSING WITH THE MOUSETRAP
"Your mousetrap has generated quite a bit of controversy," I began. "For instance, John McDonald of the University of Delaware said mousetraps can work well with fewer parts than yours-and he even drew a picture of a trap that's simpler than the one you drew. Doesn't this undermine your point that your mousetrap is irreducibly complex?"
"No, not a bit," he said with a good-natured smile. "I agree there are mousetraps with fewer parts than mine. As a matter of fact, I said so in my book! I said you can just prop open a box with a stick, or you can use a glue trap, or you can dig a hole for the mouse to fall into, or you can do any number of things.
"The point of irreducible complexity is not that one can't make some other system that could work in a different way with fewer parts. The point is that the trap we're considering right now needs all of its parts to function. The challenge to Darwinian gradualism is to get to my trap by means of numerous, successive, slight modifications. You can't do it. Besides, you're using your intelligence as you try. Remember, the audacious claim of Darwinian evolution is that it can put together complex systems with no intelligence at all."
Behe's simple explanation seemed sufficient to defeat McDonald's critique But there was a stronger challenge to consider. I reached down into my briefcase and removed a copy of Natural History magazine.
"Kenneth Miller of Brown University has another objection to your trap," I said. Then I read him Miller's comments:
Take away two parts (the catch and the metal bar), and you may not have a mousetrap but you do have a three-part machine that makes a fully functional tie clip or paper clip. Take away the spring, and you have a two-part key chain. The catch of some mousetraps could be used as a fishhook, and the wooden base as a paperweight; useful applications of other parts include everything from toothpicks to nutcrackers and clipboard holders. The point, which science has long understood, is that bits and pieces of supposedly irreducibly complex machines may have different-but still useful-functions.'
"That's a strong point," I said. "Maybe an irreducibly complex system could develop gradually over time, because each of its components could have another function that natural selection would preserve on the way toward developing a more complex machine." "That's an interesting argument," he said.
I leaned forward. "Doesn't this dismantle your case?" I asked.
Behe didn't flinch. "The problem," he replied, "is that it's not an argument against anything I’ve ever said. In my book, I explicitly point out that some of the components of biochemical machines can have other functions. But the issue remains-can you use numerous, slight, successive modifications to get from those other functions to where we are?
"Some of this objection seems a bit silly. Could a component of a mousetrap function as a paperweight? Well, what do you need to be a paperweight? You need mass. You need to exist. An elephant, or my computer, or a stick can be a paperweight. But suppose you go buy a paperweight. What would it look like? Most of them are nondescript, roundish things. None of them look anything like a precursor to a mousetrap. Besides, look at what he's doing: he's starting from the finished product-the mousetrap-and disassembling it and moving a few things around to use them for other purposes. Again, that's intelligent design!
"The question for evolution is not whether you can take a mousetrap and use its parts for something else; it's whether you can start with something else and make it into a mousetrap. The problem for evolutionists is to start with a less complex system and build a more complex system. Even if every component could theoretically have a useful function prior to its assembly into the mousetrap, you'd still have the problem of how the mousetrap becomes assembled."
"Explain further," I said.
"When people put together a mousetrap, they have the disassembled components in different drawers or something, and they grab one from each drawer and put it together. But in the cell, there's nobody there to do that.
"In molecular machines, components have portions of their shape that are complementary to each other, so they connect with each other in the right way. A positive charge can attract a negative charge, and an oily region can attract another oily region. So if we use the mousetrap as an analogy, one end of the spring would have to have a certain shape or magnetism that just happened to attract and fit with another component of the trap. They'd all have to fit together that way until you had the whole trap assembled by itself.
"In other words, if you just had the components themselves without the ability to bring the other pieces into position, you'd be far from having a functioning mousetrap. Nobody ever addresses this problem in the evolutionary literature. If you do any calculations about how likely this could occur by itself, you find it's very improbable. Even with small machines, you wouldn't expect them to self-assemble during the entire lifetime of the earth. That's a severe problem that evolutionists don't like to address."
THE AMAZING, MOVING CILIUM
The mousetrap emerged unscathed. But of course, it was only intended to be an illustration to help people understand irreducibly complex cellular systems. I decided to press forward by asking about some specific examples of molecular machines to see whether they could have developed by the step-by-step evolutionary process envisioned by Darwin. When I asked Behe for a specimen of irreducible complexity, he quickly cited the cilium.
"Cilia are whiplike hairs on the surface of cells. If the cell is stationary, the cilia move fluid across the cell's surface. For instance," he said, pointing toward my throat, "you've got cilia lining your respiratory tract. Every cell has about two hundred of them, and they beat in syn-chrony in order to sweep mucus toward your throat for elimination. That's how your body expels little foreign particles that you accidentally inhale. But cilia also have another function: if the cell is mobile, the cilia can row it through a fluid. Sperm cells would be an example; they're pro-pelled forward by the rowing action of cilia."
"That sounds fairly simple," I remarked.
"That's what scientists used to think when they examined cilia under a light microscope. They just looked like little hairs. But now that we have electron microscopes, we've found that cilia are, in fact, quite complicated molecular machines. Think about it: most hairs don't beat back and forth. What enables cilia to do this? Well, it turns out a cilium is made up of about two hundred protein parts."
"How does it function?"
He smiled. "I'll try to keep this basic," he said. "There are nine pairs of microtubules, which are long, thin, flexible rods, which encircle two single microtubules. The outer microtubules are connected to each other by what are called nexin linkers. And each microtubule has a motor protein called dynein. The motor protein attaches to one microtubule and has an arm that reaches over, grabs the other one, and pushes it down. So the two rods start to slide lengthwise with respect to each other. As they start to slide, the nexin linkers, which were originally like loose rope, get stretched and become taut. As the dynein pushes farther and farther, it starts to bend the apparatus; then it pushes the other way and bends it back. That's how you get the rowing motion of the cilium.
"That doesn't begin to do justice to the complexity of the cilium. But my point is that these three parts-the rods, linkers, and motors-are necessary to convert a sliding motion into a bending motion so the cilium can move. If it weren't for the linkers, everything would fall apart when the sliding motion began. If it weren't for the motor protein, it wouldn't move at all. If it weren't for the rods, there would be nothing to move. So like the mousetrap, the cilium is irreducibly complex."
"Why can't Darwinian evolution account for that?"
"You only get the motion of the cilium when you've got everything together. None of the individual parts can do the trick by themselves. You need them all in place. For evolution to account for that, you would have to imagine how this could develop gradually-but nobody has been able to do that."
I ventured a possibility. "Maybe these three components were being used for other purposes in the cell and eventually came together for this new function," I said. "For instance, microtubules look a bit like girders. Maybe they were used in the structure of primitive cells. Or maybe they formed the cellular highways along which the motor proteins moved material within the cell."
Belie didn't look impressed. "A motor protein that has been transporting cargo along a cellular highway might not have the strength necessary to push two microtubules relative to each other," he replied. "A nexin linker would have to be exactly the right size before it was useful at all. Creating the cilium inside the cell would be counterproductive; it would need to extend from the cell. The necessary components would have to come together at the right place at the right time, even assuming they were all pre-existing in the cell."
"Isn't it possible that they might all come together by chance?" I asked.
"It's extraordinarily improbable," he replied. "Let me illustrate it for you. Say there are ten thousand proteins in a cell. Now, imagine you live in a town of ten thousand people, and everyone goes to the county fair at the same time. Just for fun, everyone is wearing blindfolds and is not allowed to speak. There are two other people named Lee, and your job is to link hands
with them. What are the odds that you could go grab two people at random and create a link of Lees? Pretty slim. In fact, it gets worse. In the cell, the mutation rate is extremely low. In our analogy, that would mean you could only change partners at the county fair one time a year.
"So you link with two other people-sorry, they're not the other Lees. Next year, you link with two other people. Sorry, no Lees again. How long would it take you to link with the other Lees? A very, very long time-and the same is true in the cell. It would take an enormous amount of time-a prohibitive amount of time-even to get three proteins together.
"To make it even more difficult, a recent study in Science magazine found that half the proteins in a simple yeast cell don't function alone, but they function as complexes of half a dozen proteins or more. Up to fifty proteins are stuck together like cogs in a machine. Of the other fifty percent, most are in complexes of three or four. Very few work as single, Lone Ranger proteins. So this is a huge problem not only in cilia but in other cells too."
"Some scientists have pointed out that there are examples of other cilia that don't have some of the parts that you contend are essential," I said. "One said, `In nature, we can find scores of cilia lacking one or more of the components supposedly essential to the function of the apparatus.' Doesn't the existence of simpler cilia refute your contention that they are irreducibly complex?"
"If you could point to a series of less complex structures that progress from one to the other in order to create the cilia I've described, then, yes, that would refute me. But that isn't the case," he said. "What the critics say is that you can take away one of the several microtubules and the cilium would still function. That's fine. You still need all the basic components-microtubules, nexin, and dynein.
'"Let me give you an analogy. Some big mousetraps-actually, they re rat traps-have double springs to make them stronger. You can take one spring away and it would still work to a degree. In a sense, the second spring is a redundant component. The cilium is the same way; it's got some redundant components. You can take one of the microtubules away and it will still function, though maybe not as well.
"But evolution does not start with the completed trap or completed cilium and take parts away; it has to build things up from the bottom. And all cilia have the three critical components that I've mentioned. There have been experiments where scientists have removed one of the three and the cilium doesn't work. It's broken-just like you'd expect it to be, since it's an irreducibly complex machine."
THE WORLD'S MOST EFFICIENT MOTOR
As amazing as the cilium is, I was even more fascinated by another biological machine for propelling cells-the bacterial flagellum. "While cilia act like oars to move cells, it was discovered in 1973 that the flagellum performs like a rotary propeller," Behe explained. "Only bacteria have them."
"How does it work?" I asked.
"Extremely efficiently," he said. "Just picture an outboard motor on a boat and you get a pretty good idea of how the flagellum functions, only the flagellum is far more incredible. The flagellum's propeller is long and whiplike, made out of a protein called flagellin. This is attached to a drive shaft by hook protein, which acts as a universal joint, allowing the propeller and drive shaft to rotate freely. Several types of proteins act as bushing material to allow the drive shaft to penetrate the bacterial wall and attach to the rotary motor."
"Where does it get its energy?" I asked
"That's an interesting phenomenon," he replied. "Some other biological systems that generate movement, like muscles, use energy that has been stored in what's called a `carrier molecule.' But the flagellum uses another system-energy generated by a flow of acid through the bacterial membrane. This is a complex process that scientists are still studying and trying to understand. The whole system works really well-the flagellum's propeller can spin at ten thousand revolutions per minute."
As a car aficionado, I was staggered by that statistic! A friend had recently given me a ride in his exotic high-performance sports car, and I knew it wasn't capable of generating that many rpms. Even the notoriously high-revving Honda S2000, with a state-of-the-art, fourcylinder, two-liter, dual-overhead-cam aluminum block engine, featuring four valves per cylinder and variable intake and exhaust valve timing, has a redline of only nine thousand rpms.9
"Not only that," Behe continued, "but the propeller can stop spinning within a quarter turn and instantly start spinning the other way at ten thousand rpms. Howard Berg of Harvard University called it the most efficient motor in the universe. It's way beyond anything we can make, especially when you consider its size."
"How small is it?"
"A flagellum is on the order of a couple of microns. A micron is about 1/20,000 of an inch. Most of its length is the propeller. The motor itself would be maybe 1/100,000ths of an inch. Even with all of our technology, we can't even begin to create something like this. Sometimes in my lectures I show a drawing of the flagellum from a biochemistry textbook, and people say it looks like something from NASA. If you think about it, we've discovered machines inside our-selves. On Star Trek they had a creature called the Borg, which has tiny machines inside. Well, it turns out everybody does!"
Drawings of the flagellum are, indeed, very impressive, since they look uncannily like a machine that human beings would construct. I remember a scientist telling me about his father, an accomplished engineer who was highly skeptical about claims of intelligent design. The dad could never understand why his son was so convinced that the world had been designed by an intelligent agent. One day the scientist put a drawing of the bacterial flagellum in front of him. Fascinated, the engineer studied it silently for a while, then looked up and said to his son with a sense of wonder: "Oh, now I get what you've been saying."
"Think of this too," Behe continued. "Imagine a boat with its motor running. Uh-oh! Nobody's steering it. It goes out and crashesboom! Well, who's steering the bacterial cell? It turns out it has sensory systems that feed into the bacteria flagellum and tell it when to turn on and when to turn off, so that it guides it to food, light, or whatever it's seeking. In a sense, it's like those smart missiles that have guidance systems to help them find their target, except there's no explosion at the end!"
"And the flagellum is irreducibly complex?"
"That's right," he said. "Genetic studies have shown that between thirty and thirty-five proteins are needed to create a functional flagellum. I haven't even begun to describe all of its complexities; we don't even know the roles of all its proteins. But at a minimum you need at least three parts-a paddle, a rotor, and a motor-that are made up of various proteins. Eliminate one of those parts and you don't get a flagellum that only spins at five thousand rpms; you get a flagellum that simply doesn't work at all. So it's irreducibly complexand a huge stumbling block to Darwinian theory."
I asked, "Has anyone been able to propose a step-by-step evolutionary explanation of how a
gradual process could have yielded a flagellum?"
"In a word-no," he said with a chuckle. "For most irreducibly complex systems, the best you get is a sort of hand-waving, cartoonish explanation, but certainly nothing that approaches being realistic. Even evolutionary biologist Andrew Pomiankowski admitted: `Pick up any biochemistry textbook, and you will find perhaps two or three references to evolution. Turn to one of these and you will be lucky to find anything better than `evolution selects the fittest mole-cules for their biological function.'
"But for the flagellum, there aren't even any cartoon explanations. The best the Darwinists have been able to muster is to say that the flagellum has components that look like the components of other systems that don't have as many parts, so maybe somehow this other system had something to do with the flagellum. Nobody knows where this subsystem came from in the first place, or how or why the subsystem may have turned into a flagellum. So, no, there's no reasoned explanation anyone has been able to offer."
I tried another approach. "What about Darwinists who say, `Maybe it's merely too early for us to come up with a road map of how these gradual changes developed. Someday we'll better understand the flagellum, so have patience-in the end, science is going to figure it out."'
Behe leaned back in his chair. "You know, Darwinists always accuse folks in the Intelligent Design movement of making an argument from ignorance. Well, that's a pure argument from ignorance! They're saying, `We have no idea how this could have happened, but let's assume evolution somehow did it.' You've heard of 'Godof-the-gaps'-inserting God when you don't have another explanation? Well, this is 'evolution-of-the-gaps.' Some scientists merely insert evolution when they don't understand something.
"Look-we may not understand everything about these biological systems, but we do know some things. We do know that these systems have a number of very specifically matched components that do not lend themselves to a gradualistic explanation. We know that intelligence can assemble complex systems, like computers and mousetraps and things like that. The complexity we see is not going to be alleviated by the more we learn; it can only get more complicated. We will only discover more details about the systems.
"Here's an illustration. Let's say you have a car in a dark garage. You shine a flashlight on one part of the engine and you see all of its components and its obvious complexity. Shining the flashlight on another part of the motor isn't going to make the first part go away. It isn't going to make the problem any simpler; it's going to make it more complicated. And as we discover more about the flagellum, it won't negate the complexity we've already found. All we'll have is an even more complicated, more impressive, more interdependent machineand an even greater challenge to Darwinian theory."
MOLECULAR TRUCKS AND HIGHWAYS
According to Behe, the cilium and bacterial flagellum are just the beginning of the Darwin-defying complexity in the microscopic world of the cell. One of his other favorites is the "intra-cellular transport system."
"The cell is not a simple bag of soup, with everything sloshing around," he said. "Instead, eukaryotic cells-cells of all organisms except bacteria-have a number of compartments, sort of like rooms in a house.
"There's the nucleus, where the DNA resides; the mitochondria, which produce energy; the endoplasmic reticulum, which processes proteins; the Golgi apparatus, which is a way station for proteins that are being transported elsewhere; the lysosome, which is a garbage disposal unit; secretory vesicles, which store cargo before it's sent out of the cell; and the peroxisome, which helps metabolize fats. Each compartment is sealed off by a membrane, just like a room has walls and a door. In fact, the mitochondrion has four separate sections. Counting everything, there are more than twenty different sections in each cell.
"Cells are constantly getting rid of old stuff and manufacturing new components, and these components are designed to work in one room but not others. Most new components are made at a central location in the cell on things called ribosomes."
Denton has described the ribosome, a collection of some fifty large molecules containing more than one million atoms, as an automated factory that can synthesize any protein that it is instructed to make by DNA. Given the correct genetic information, in fact, it can construct any protein-based biological machine, including another ribosome, regardless of the complexity. Denton marveled:
It is astonishing to think that this remarkable piece of machinery, which possesses the ultimate capacity to construct every living thing that has ever existed on Earth, from a giant redwood to the human brain, can construct all its own components in a matter of minutes and ... is of the order of several thousand million million times smaller than the smallest piece of functional machinery ever constructed by man."
"Not only is the ribosome amazing," Behe said, "but now you're faced with the challenge of getting these new components into the right rooms where they can operate. In order to do that, you need to have another complicated system, just like you need a lot of things in place for a Greyhound bus to take someone from Philadelphia to Pittsburgh.
"First of all, you've got to have molecular trucks, which are enclosed and have motors attached to them. You've got to have little highways for them to travel along. You've got to be able to identify which components are supposed to go into which truck-after all, it doesn't do any good if you just grab any protein that comes along, because each one needs to go to a specific room. So there has to be a signal attached to the protein-sort of a ticket-to let the protein onto the right molecular truck. The truck has to know where it's going, which means having a signal on the truck itself and a complementary signal on the compartment where the truck is supposed to unload its cargo.
"When the truck arrives where it's supposed to go, it's kind of like a big ocean liner that has crossed from London to New York. It pulls up at the dock and everyone's waving-but, oops, they forgot the gang plank. Now what are you going to do? You see, you've got to have a way for the cargo to get out of the truck and into the compartment, and it turns out this is an active process that involves other components recognizing each other, physically opening things up, and allowing the material to go inside.
"So you've got numerous components, all of which have to be in place or nothing works. If you don't have the signal, if you don't have the truck, you're pretty much out of luck. Now, does this microscopic transportation system sound like something that self-assembled by gradual modifications over the years? I don't see how it could have been. To me, it has all the earmarks of being designed."
THE BLOOD-CLOTTING CASCADE
There was a pause in our conversation as my mind processed the stupefying complexity of the cilium, flagellum, and intracellular transport system. As I began to formulate my next line of questioning, Behe noticed a Band-Aid on one of my fingers, covering a cut I had received while
picking up pieces of broken glass the previous day.
"Irreducible complexity is a very relevant topic," he commented as he gestured toward the bandage. "An irreducibly complex system just saved your life."
"What do you mean?" I asked.
"Blood clotting," he said. "If your blood hadn't clotted in the right place and in the right amount and at the right time, you would have bled to death. As it turns out, the system of blood clotting involves a highly choreographed cascade of ten steps that use about twenty different molecular components. Without the whole system in place, it doesn't work."
Suddenly, I felt a personal stake in the topic. "Tell me more," I said.
"The real trick with blood clotting isn't so much the clot itself-it's just a blob that blocks the flow of blood-but it's the regulation of the system," he continued.
"If you make a clot in the wrong place-say, the brain or lung you'll die. If you make a clot twenty minutes after all the blood has drained from your body, you'll die. If the blood clot isn't confined to the cut, your entire blood system might solidify, and you'll die. If you make a clot that doesn't cover the entire length of the cut, you'll die. To create a perfectly balanced blood-clotting system, clusters of protein components have to be inserted all at once. That rules out a gradualistic Darwinian approach and fits the hypothesis of an intelligent designer."
Surely, I thought to myself, there must be another way. "Some scientists have proposed that a process called `gene duplication' can account for the creation of new components for complex biological systems," I said. "Why wouldn't that work with blood clotting?"
Gene duplication can happen during the process of cell division when DNA is being copied from the original cell for use in the new cell. Occasionally, the process goes awry and a piece of DNA, perhaps a gene, is copied twice. This creates an extra gene. While the original gene can go about its pre-assigned role, the extra gene can drift and perhaps create a new function. Some scientists have theorized that this is how new components might be created for irreducible systems.
"Sure, gene duplication happens," Behe replied. "But what the fans of gene duplication rarely recognize is that when you get a duplicated gene, you don't get a new protein with new properties. You've got the same protein as before. And that's a problem."
I was having difficulty seeing why. "Could you explain that?" I asked.
He glanced down at the mousetrap, which was still sitting on his desk. "Let's go back to the mousetrap analogy," he said. "Suppose you have a one-component mousetrap, with two ends of a metal spring being bent and pressing against each other under tension so that if a mouse disturbs them, they'll slip and spring and hopefully catch a paw or tail. And say you wanted to develop a more efficient two-component trap that has a wooden base as well as the spring.
"According to the concept of gene duplication, you would make a copy of the first spring. Now you've got two springs-except the second spring somehow becomes a wooden base. Do you see the conceptual disconnect? You can't just say the spring somehow morphs into a wooden base without doing more than just saying, `gene duplication did it.' The problem is, Darwinists don't provide the details of how this can actually happen in the real world.
"When one scientist tried to come up with a step-by-step scenario of how blood-clotting could have developed, he couldn't avoid generalizing by saying a component suddenly `appears,' or `is born,' or, `arises,' or, `springs forth,' or `is unleashed."' What's causing all of this springing forth and unleashing? There's no meaningful explanation of what could have caused these steps to take place. These are details that doom these scenarios.
"And there are a lot more problems than that. How can blood clotting develop over time, step
by step, when in the meantime the animal has no effective way to stop from bleeding to death whenever it's cut? And when you've only got part of a system in place, the system doesn't work, so you've got the components sitting around doing nothing-and natural selection only works if there is something useful right now, not in the future.
"Besides, at best the explanations that some people attempt are mere word pictures. In science we're supposed to do experiments to show something is true. Nobody has ever done experiments to show how blood-clotting could have developed. Nobody has been able to show how a duplicated gene can develop some new function where it starts to make a new and irreducibly complex pathway."
SURVIVING THE ACID TEST
There is a scientific way, however, to establish through experimental data whether Belie's concept of irreducible complexity is really an insuperable barrier for Darwinism. I was anxious to see whether Behe's ideas could survive this formidable challenge from Miller, a biology professor who's an ardent and outspoken evolutionist.
The "true acid test," explained Miller, would be to use "the tools of molecular genetics to wipe out an existing multi-part system and then see if evolution can come to the rescue with a system to replace it."13 If the system can be replaced purely by naturalistic evolutionary processes, then Behe's theory has been disproved.
After describing Miller's challenge, I asked Behe: "Do you agree this would be a fair test?" Without hesitation, he said: "Yes, I agree. That's a terrific test."
Then I said: "Miller went on to describe an experiment by scientist Barry Hall of the University of Rochester to show how this apparently was done in the laboratory. Miller concluded: `No doubt about it-the evolution of biochemical systems, even complex multi-part ones, is explicable in terms of evolution. Behe is wrong."'14
I faced Behe squarely. "Tell me, has Hall proved through his experiment that your theory is incorrect?"
Unflustered, Behe replied: "No, not really. Actually, Hall is very modest about what his experiment shows. He didn't knock out a complex system and then show how evolution can replace it. Instead, he knocked out one component of a system that has five or six components. And replacing one component in a complex system is a lot easier than building one from scratch.
"For instance, suppose someone told you that natural processes could produce a working television set. You'd say, `That's interesting. Why don't you show me?' He would then unplug a thousand television sets. Eventually, a strong wind would come along and blow one plug back into the outlet, and the TV would come on. He would say, `See? I told you that natural processes could produce a working TV.' But that's not exactly what happened. He wasn't producing a new complex system; there was a glitch introduced and he showed that on occasion this can be fixed by random processes.
"That's a little like what went on with Hall's experiment with the bacterium E. coll. There was a complex system with a number of different parts, he knocked out one of them, and after a while he showed that random processes came up with a fix for that one part. That's a far cry from producing a brand new system from scratch.
"But there's something equally important: Hall made it clear that he had intervened to keep the system going while evolution was trying to come up with a replacement for the missing part. In other words, he added a chemical to the mixture that gave it the time to come up with the mutation that fixed the glitch. The result never would have actually happened in nature without
his intelligent intervention in the experiment.
"Here's another analogy. Suppose you say you can make a three-legged stool by random processes. You take a three-legged stool and break off one leg. Then you hold up the stool so it won't fall over. Finally, a wind comes along, knocks down a tree branch, and it accidentally falls right where the missing leg had been. You're intervening to help the stool through the stage where it would otherwise have fallen over and you've made it possible for the branch to fit in the right place.
"Back to Hall's experiment. Without going into the technical details, which I've done in more formal responses,'' in nature you couldn't have gotten just the mutation that he got in the laboratory. You would have had to have simultaneously gotten a second mutation-and the odds of that would have been prohibitive. Hall made it clear that he intervened so that he would get results that would never have actually happened in the natural world. And that is injecting intelligence into the system.
"When you analyze the entire experiment, the result is exactly what you would expect of irreducible complexity requiring intelligent intervention. Unintentionally, he has shown the limits of Darwinism and the need for design."
WHIRLPOOLS AND TORNADOES
"What about other alternatives to Darwinian gradualism?" I asked. "How about self-organization? Maybe there's some sort of selforganizational property in biochemistry that encourages the parts of molecular machines to self-assemble."
"Just like natural selection explains some things, self organization explains some things too. The controversy arises when they're used to explain big things or everything," Behe said.
"It's true that if you pull out the plug in your bathtub, the water forms a little whirlpool. That's self-organization: the water is moving in an organized fashion whereas it wasn't before. Tornadoes organize themselves. If you mix chemicals together in a certain way, you get a system that acts like a clock. It will turn blue, five seconds later it will turn colorless, and it will oscillate back and forth. So it's clear that there is such a thing as self-organization.
"The question is, can it explain more complicated phenomena? Can it explain the genetic code? Scientists trying to solve the riddle of the origin of life have been exploring self-organizational properties for decades. Yet today they're more confused about the origin of life than fifty years ago. They haven't come up with any explanation for how self-organization could account for something as complex as even the first primitive living organism.
"Right now, there's only one principle that we know can come up with complex interactive systems, and that's intelligence. Natural selection has been proposed, but there's little or no evidence backing that claim. Some people had high hopes for self-organizational properties or complexity theory, but there's no evidence that these can explain something as complicated as the cell. The only force known to be able to make irreducibly complex machines is intelligent design.
"So scientists are in the curious position of ignoring something they know to be capable of explaining what they see in biology, in favor of phantom or totally unproven explanations. Why ignore intelligent design when it's a good match to the data? Yes, we have to keep an open mind in science, but we shouldn't be ignoring the most obvious explanation for all the evidence we have today."
"One reason some scientists are reluctant," I said, "is because they claim intelligent design is not falsifiable." I was referring to the belief among many philosophers and scientists that a
theory cannot truly be scientific unless there are potential ways to prove it false through experiments or other means.16
"That's silly," Behe replied.
"But I hear it over and over," I insisted. "The National Academy of Sciences said: `Intelligent design ... [is] not science because [it's] not testable by the methods of science."'
"Yes, I know," he said, "but what's really ironic is that intelligent design is routinely called unfalsifiable by the very people who are busy trying to falsify it! As you just pointed out, Miller proposed a test that would falsify the claim that intelligence is needed to produce an irreducibly complex system. So I don't see the problem. Intelligent design's strong point is that it's falsifiable, just like a good scientific theory should be. Frankly, I'd say it's more falsifiable than Darwinism is."
"Come on," I said. "Do you really believe that?"
"Yes, I do, and I'll give you an example," he replied. "My claim is that there is no unintelligent process that could produce the bacterial flagellum. To falsify that claim, all you would have to do would be to find one unintelligent process that could produce that system. On the other hand, Darwinists claim that some unintelligent process could produce the flagellum. To falsify that, you'd have to show that the system could not possibly have been created by any of a potentially infinite number of possible unintelligent processes. That's impossible to do. So which claim is falsifiable? I'd say the claim for intelligent design."
That isn't the only objection that Behe has turned on its head. While Darwinists often accuse intelligent design proponents of letting their religious beliefs color their science, Behe once told a newspaper reporter: "It has been my experience ... that the ones who oppose the theory of design most vociferously do so for religious reasons.""8
"What did you mean by that?" I asked.
"It seems that the folks who get the most animated when talking about Darwinian evolution are the ones most concerned with the philosophical and theological ramifications of the theory, not the science itself," he explained.
"Scientists propose hypotheses all the time. No big deal. But if I say, `I don't think natural selection is the driving force for the development of life; I think it was intelligent design,' people don't just disagree; many of them jump up and down and get red in the face. When you talk to them about it, invariably they're not excited because they disagree with the science; it's because they see the extra-scientific implications of intelligent design and they don't like where it's leading."
Behe shrugged. "I guess that's okay," he added. "These are important issues and people can get emotional about them. But we should not use what we want to be true to dismiss arguments or try to avoid them."
THE ARROW OF PROGRESS
Behe's concept of irreducible complexity is at once a negative and a positive argument. First, he has taken Darwin at his own word and demonstrated how these interconnected biological systems could not have been created through the numerous, successive, slight modifications that his theory demands. The result has been a staggeringsome say lethal-blow to Darwinism.
Second, Behe has pointed out that there is an alternative that does sufficiently explain how complex biological machines could have been created. Once again, as with the previous experts I had interviewed on cosmology, physics, and astronomy, the evidence conspires to point toward a transcendent Creator.
"My conclusion can be summed up in a single word: design," Behe said as we came to the end of our interview. "I say that based on science. I believe that irreducibly complex systems are strong evidence of a purposeful, intentional design by an intelligent agent. No other theory succeeds; certainly not Darwinism.
"Based on the empirical evidence-which is continuing to mount-I'd agree with Joseph Cardinal Ratzinger that `the great projects of the living creation are not the products of chance and error.... [They] point to a creating Reason and show us a creating Intelligence, and they do so more luminously and radiantly today than ever before."'19
"Your book has been out for several years now," I said. "How well do you think it has endured so far?"
"I'm very pleased with how things stand," he said, leaning back in his chair and casually folding his arms over his chest. "It has attracted a lot of attention from people who have tried to knock it down, but they haven't been able to do it. Complex biological systems have yet to be explained by naturalistic means. That's a fact. Even Darwinists admit that in their candid moments. And as science advances, we're continuing to find more and more complexity in the cellular world. This, Lee, is the arrow of progress.
"I do hear occasional complaints that science needs to pretend that everything works by natural law and that intelligent design is `giving up.' I've never seen the logic of that. The purpose of science, it seems to me, is to find out how things got here and how they work. Science should be the search for truth, not merely the search for materialistic explanations. The great scientists of history-Newton and Einstein, for instance-never thought science's job was to come up with some sort of self-sufficient explanation for nature. This is a recent innovation, and not a good one-especially in light of discoveries during the last fifty years that have pointed in the exact opposite direction."
Behe and I continued to talk for a while, then we shook hands and parted ways. As I lingered in the hallway, peering through the glass into various laboratories where scientists were hard at work, I thought of the concession by microbiologist James Shapiro of the University of Chicago in his review of Behe's book: "There are no detailed Darwinian accounts for the evolution of any fundamental biochemical or cellular system, only a variety of wishful speculations."20
Shapiro might not be amenable to Behe's ultimate conclusions, but personally I wasn't ready to bank on wishful speculations. Connecting the dots from my interviews with William Lane Craig, Robin Collins, Guillermo Gonzalez, Jay Richards, and now Michael Behe, I was coming up with a picture that was squarely at odds with the icons that had once led me into atheism. In the words of Allan Sandage, one of the most highly respected scientists of our age:
The world is too complicated in all its parts and interconnections to be due to chance alone. I am convinced that the existence of life with all its order in each of its organisms is simply too well put together. Each part of a living thing depends on all its other parts to function. How does each part know? How is each part specified at conception? The more one learns of biochemistry the more unbelievable it becomes unless there is some type of organizing principle-an architect for believers, a mystery to be solved by science (even as to why) sometime in the indefinite future for materialist reductionalists.21
That mystery was going to take me even deeper inside the awe-inspiring, microscopic realm of the cell. As I started my rental car and began to drive down the asphalt road from Lehigh's Mountaintop Campus, I remembered that Stephen Meyer, the philosopher of science I had
already interviewed about the relationship between science and faith, has written extensively on DNA. This seemed like a good time for a new chat about where the arrow of genetics might be pointing.