Christopher Hitchens - The Portable Atheist - Essential Readings for the Nonbeliever

Without a word of justification, explanation or amplification, Behe simply proclaims the bacterial flagellar motor to be irreducibly complex. Since he offers no argument in favour of his assertion, we may begin by suspecting a failure of his imagination. He further alleges that specialist biological literature has ignored the problem. The falsehood of this allegation was massively and (to Behe) embarrassingly documented in the court of Judge John E. Jones in Pennsylvania in 2005, where Behe was testifying as an expert witness on behalf of a group of creationists who had tried to impose “intelligent design” creationism on the science curriculum of a local public school—a move of “breathtaking inanity,” to quote Judge Jones (phrase and man surely destined for lasting fame). This wasn’t the only embarrassment Behe suffered at the hearing, as we shall see.

The key to demonstrating irreducible complexity is to show that none of the parts could have been useful on its own. They all needed to be in place before any of them could do any good (Behe’s favourite analogy is a mousetrap). In fact, molecular biologists have no difficulty in finding parts functioning outside the whole, both for the flagellar motor and for Behe’s other alleged examples of irreducible complexity. The point is well put by Kenneth Miller of Brown University, for my money the most persuasive nemesis of “intelligent design,” not least because he is a devout Christian. I frequently recommend Miller’s book, Finding Darwin’s God, to religious people who write to me having been bamboozled by Behe.

In the case of the bacterial rotary engine, Miller calls our attention to a mechanism called the Type Three Secretory System or TTSS. The TTSS is not used for rotatory movement. It is one of several systems used by parasitic bacteria for pumping toxic substances through their cell walls to poison their host organism. On our human scale, we might think of pouring or squirting a liquid through a hole; but, once again, on the bacterial scale things look different. Each molecule of secreted substance is a large protein with a definite, three-dimensional structure on the same scale as the TTSS’s own: more like a solid sculpture than a liquid. Each molecule is individually propelled through a carefully shaped mechanism, like an automated slot machine dispensing, say, toys or bottles, rather than a simple hole through which a substance might “flow.” The goods-dispenser itself is made of a rather small number of protein molecules, each one comparable in size and complexity to the molecules being dispensed through it. Interestingly, these bacterial slot machines are often similar across bacteria that are not closely related. The genes for making them have probably been “copied and pasted” from other bacteria: something that bacteria are remarkably adept at doing, and a fascinating topic in its own right, but I must press on.

The protein molecules that form the structure of the TTSS are very similar to components of the flagellar motor. To the evolutionist it is clear that TTSS components were commandeered for a new, but not wholly unrelated, function when the flagellar motor evolved. Given that the TTSS is tugging molecules through itself, it is not surprising that it uses a rudimentary version of the principle used by the flagellar motor, which tugs the molecules of the axle round and round. Evidently, crucial components of the flagellar motor were already in place and working before the flagellar motor evolved. Commandeering existing mechanisms is an obvious way in which an apparently irreducibly complex piece of apparatus could climb Mount Improbable.

A lot more work needs to be done, of course, and I’m sure it will be. Such work would never be done if scientists were satisfied with a lazy default such as “intelligent design theory” would encourage. Here is the message that an imaginary “intelligent design theorist” might broadcast to scientists: “If you don’t understand how something works, never mind: just give up and say God did it. You don’t know how the nerve impulse works? Good! You don’t understand how memories are laid down in the brain? Excellent! Is photosynthesis a bafflingly complex process? Wonderful! Please don’t go to work on the problem, just give up, and appeal to God. Dear scientist, don’t work on your mysteries. Bring us your mysteries, for we can use them. Don’t squander precious ignorance by researching it away. We need those glorious gaps as a last refuge for God.” St. Augustine said it quite openly: “There is another form of temptation, even more fraught with danger. This is the disease of curiosity. It is this which drives us to try and discover the secrets of nature, those secrets which are beyond our understanding, which can avail us nothing and which man should not wish to learn” (quoted in Freeman 2002).

Another of Behe’s favourite alleged examples of “irreducible complexity” is the immune system. Let Judge Jones himself take up the story:

In fact, on cross-examination, Professor Behe was questioned concerning his 1996 claim that science would never find an evolutionary explanation for the immune system. He was presented with fifty-eight peer-reviewed publications, nine books, and several immunology textbook chapters about the evolution of the immune system; however, he simply insisted that this was still not sufficient evidence of evolution, and that it was not “good enough.”

Behe, under cross-examination, by Eric Rothschild, chief counsel for the plaintiffs, was forced to admit that he hadn’t read most of those fifty-eight peer-reviewed papers. Hardly surprising, for immunology is hard work. Less forgivable is that Behe dismissed such research as “unfruitful.” It certainly is unfruitful if your aim is to make propaganda among gullible laypeople and politicians, rather than to discover important truths about the real world. After listening to Behe, Rothschild eloquently summed up what every honest person in that courtroom must have felt:

Thankfully, there are scientists who do search for answers to the question of the origin of the immune system… It’s our defense against debilitating and fatal diseases. The scientists who wrote those books and articles toil in obscurity, without book royalties or speaking engagements. Their efforts help us combat and cure serious medical conditions. By contrast, Professor Behe and the entire intelligent design movement are doing nothing to advance scientific or medical knowledge and are telling future generations of scientists, don’t bother.

As the American geneticist Jerry Coyne put it in his review of Behe’s book: “If the history of science shows us anything, it is that we get nowhere by labelling our ignorance ‘God.’” Or, in the words of an eloquent blogger, commenting on an article on intelligent design in the Guardian by Coyne and me,

Why is God considered an explanation for anything? It’s not—it’s a failure to explain, a shrug of the shoulders, an “I dunno” dressed up in spirituality and ritual. If someone credits something to God, generally what it means is that they haven’t a clue, so they’re attributing it to an unreachable, unknowable sky-fairy. Ask for an explanation of where that bloke came from, and odds are you’ll get a vague, pseudo-philosophical reply about having always existed, or being outside nature. Which, of course, explains nothing.

Darwinism raises our consciousness in other ways. Evolved organs, elegant and efficient as they often are, also demonstrate revealing flaws—exactly as you’d expect if they have an evolutionary history, and exactly as you would not expect if they were designed. I have discussed examples in other books: the recurrent laryngeal nerve, for one, which betrays its evolutionary history in a massive and wasteful detour on its way to its destination. Many of our human ailments, from lower back pain to hernias, prolapsed uteruses and our susceptibility to sinus infections, result directly from the fact that we now walk upright with a body that was shaped over hundreds of millions of years to walk on all fours. Our consciousness is also raised by the cruelty and wastefulness of natural selection. Predators seem beautifully “designed” to catch prey animals, while the prey animals seem equally beautifully “designed” to escape them. Whose side is God on?