Faulty Design


It would be difficult to name a scientific idea that causes more unease, more bewilderment, or more opposition than Charles Darwin’s theory of evolution. Evolution has been the target of textbook protests, board-of-education elections, state laws, show trials, and even Supreme Court decisions. So powerful and far-reaching is the idea that it has even led its most ardent enthusiasts to suggest that evolutionary analysis will soon step beyond science to overwhelm traditional ways of thinking in the arts and humanities (see Consilience, by E. O. Wilson). Presidential candidates feel obliged to comment on their acceptance or rejection of the idea, and the question literally splits the U.S. population right down the middle. (A 2005 Harris poll found that 46 percent of Americans agreed with the statement that “Darwin’s theory of evolution is proven by fossil discoveries,” while 48 percent disagreed.) Into this contentious fray steps Michael Behe, Lehigh University biochemist and advocate of “intelligent design” (ID). Behe’s credentials as an opponent of evolution are well established. His 1996 book, Darwin’s Black Box, is a classic of the antievolution movement. He is senior fellow of the pro-ID Discovery Institute, and served as an expert witness in favor of the ID policy promoted by the Dover, Pennsylvania, Board of Education. His new book, The Edge of Evolution, will surely attract a passionate following among the antievolution crowd. As someone who has publicly defended evolution against attacks from the ID movement (I served as an opposing witness in the Dover trial), I might be expected to be very critical of Behe’s new book, and so I will be. But the book contains a genuine surprise-a blanket concession to what nearly all Americans would regard as the core of Darwin’s theory: the notion of common descent. Ask Darwin doubters what they find objectionable about evolution, and as often as not the answer will be the wretched notion that “we came from monkeys.” More than half of all Americans, in fact, would agree with the assertion that humankind was created in more or less its present form in the last ten thousand years. What does Behe have to say to these folks, the heart and soul of the antievolution movement? We do indeed come from other primates, so get over it! At the Dover trial, I showed the court a slide demonstrating that the human and chimpanzee genomes share a series of molecular errors in their DNA. Remarkably, these mistakes match each other precisely, indicating beyond a doubt that humans share a common ancestor with the chimpanzee. To my amazement, I discovered that Behe’s book includes a nearly exact copy of the diagram I used in the Dover trial. He pulls no punches as to its meaning. “It’s hard to imagine how there could be stronger evidence for common ancestry of chimps and humans,” he observes. What’s more, he continues, “The bottom line is this. Common descent is true.” Those hoping that Behe would argue for a biblical version of human origins will be shocked. Indeed, Behe tells his readers that there must be “no relying on holy books or prophetic dreams,” and that it “would be silly” to treat the Bible “as some sort of scientific textbook.” Amen. Where, then, is a role for the “intelligent designer” for which Behe has so long argued? His book’s subtitle, citing a search for “the limits of Darwinism,” provides a clue. Evolution, Behe freely admits, can do great things. It is responsible for drug resistance in microbes, for human traits like sickle-cell that counter the deadly threat of malaria, and perhaps even for the formation of new species. But evolution has its limits, and this book places those limits at a very low level. Shifting into technical language that has an air of studied authenticity, Behe correctly points out that cells are filled with complex protein-to-protein interactions. These interactions do everything from transmitting environmental signals to copying DNA. Evolution, he argues, couldn’t have produced even a single one of these protein-to-protein interactions. Behe says that they lie well beyond the “edge of evolution” (hence the book’s title). To support that assertion, he claims that the odds that evolution could produce a new protein-to-protein interaction would be no better than one chance in 1,040. Such an event would be so improbable that it “would not be expected to have happened by Darwinian processes in the history of the world.” I don’t doubt that these odds will impress many readers-cold, dispassionate math seems to show that Darwinian evolution is simply impossible. Evolution itself cannot account for the biochemical complexity of life, much less for the dramatic changes we see in the fossil record, and for Behe that means we are on sound scientific ground to invoke “design” to explain the history of life. Sadly, most of Behe’s readers will not appreciate the magnitude of the error he has built into these numbers. What he has done, as reviews in several scientific journals have already pointed out, is calculate probabilities that depend upon a predetermined set of mutations occurring in the same gene at the same time in a single individual organism. But evolution simply doesn’t work that way. By ruling out any role for natural selection until each of the mutations he requires has “randomly” appeared in the same individual organism, Behe has presented a cartoon version of the process, one that is completely at odds with scientific reality. In short, his numbers are wrong, and they’re even wrong for his chosen example of drug resistance to malaria. Behe’s miscalculations fit a pattern of incorrect claims concerning evolution that date back at least to his 1993 work on the textbook Of Pandas and People. In that book he made claims about the proteins of blood-clotting pathways that were exposed as false at the Dover trial. In 1994 he claimed that intermediate fossil forms would not be found linking whales with land-dwelling mammals. Such fossils have since been found in abundance. His well-known 1996 claim (in Darwin’s Black Box) that complex biochemical systems are “irreducibly complex” was likewise disproved in the face of more detailed research on systems, such as the bacterial flagellum and eukaryotic cilium. All these failures were in plain view when Behe’s scientific arguments collapsed under a devastating cross-examination in the Dover trial, and this book wouldn’t have changed a thing-except to place one more flawed argument on the table for a painful dissection. A hopeful reader might be forgiven if he dismissed my criticisms as little more than partisan carping from a true believer from the “evolutionist” camp. After all, if God exists, he would indeed be an “intelligent designer” of the very highest order. So, why shouldn’t we regard this provocative book as a helpful and timely scientific defense against the forces of atheistic materialism? One reason, as I mentioned, is that what it says is wrong. Its scientific arguments are built on a mistakenly improbable view of evolution. There is, however, a deeper reason that will also be of interest to Commonweal readers: Behe’s view of the designer. The final chapter of The Edge is a confusing investigation of the nature of the “designer,” as implied by Behe’s case against evolution. Behe happily notes, as I would, that we live in a universe whose fundamental physical constants are remarkably hospitable to life. To me, and apparently to Behe, these constants may well reflect the will of a creator we would both identify as the God of Abraham. That, however, is where we part company. Behe’s designer-God never gets it quite right. Behe accepts at face value common descent and the long natural history of life, but he attributes their complex features to the mutational tinkering of the designer. As a result, Behe’s interventionist God had to produce millions of failed species over billions of years to arrive at the present state of the world. If today’s world were God’s only intent, just how “intelligent” could he be? Furthermore, it turns out that this designer-God has crafted some pretty awful things along the way. One wonders about the day he designed the malaria parasite so well that it could kill a million children a year, or the polio genome that crippled my aunt, or the parasites that eat the livers of millions of souls in the tropics. To Behe, these are not byproducts of a fruitful and creative natural world that also gave us the beauty of a sunset, the grace of the eagle, and the talent of a Beethoven. No, each vicious parasite and fatal disease is the direct and intentional work of the designer. This isn’t my conclusion; it’s Behe’s. In fact, he advises us to face the terrible pain of the designer’s work, taking comfort only in the Yiddish proverb,“If God lived on earth, people would break his windows.” And for Behe’s God, that just might be true. Even more confusing is Behe’s attempt to meld this version of design with science. He tries to argue that his God need not intervene to produce change because “the purposeful design of life to any degree is easily compatible with the idea that, after its initiation, the universe unfolded exclusively by the intended playing out of natural laws.” Really? Behe has just provided two hundred pages of passionate argument that natural laws are not sufficient to explain evolutionary change, only to turn around and claim that they are. His core argument is that the natural laws that produce mutations cannot generate the diversity needed to explain evolutionary change. Then he insists that the unfolding of our universe is governed entirely by those same natural laws. And Behe does nothing to dispel this self-contradiction. In reality, the scientific and theological confusion promoted by this book are completely unnecessary. At the conclusion of the Dover trial, conservative columnist Charles Krauthammer summed up the theological confusion of the ID movement this way: How ridiculous to make evolution the enemy of God. What could be more elegant, more simple, more brilliant, more economical, more creative, indeed more divine than a planet with millions of life forms, distinct and yet interactive, all ultimately derived from accumulated variations in a single double-stranded molecule, pliable and fecund enough to give us mollusks and mice, Newton and Einstein? Even if it did give us the Kansas State Board of Education, too. Indeed it did. And now evolution has given us a book that accepts nearly every Darwinian principle, including common descent, disparaging only the adequacy of “random” mutation to produce the variation needed for natural selection to work. Regrettably, on this point, Behe’s numbers are wrong, his arguments contrived, and his logic flawed. The Edge is a work that will generate no scientific tests, no experiments, and no discoveries, yet it will certainly become a standard-issue weapon in the wars against scientific reason that will continue to sweep across our land in the years ahead. We are at a critical point in the struggle for scientific understanding in this country-and this badly flawed book seeks to move us in exactly the wrong direction.

Published in the 2007-10-12 issue: 

Kenneth R. Miller is professor of biology at Brown University.

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