"The relief prayed for is granted." With
those words, on January 5, 1982, Federal Judge William K. Overton struck
down a state law that would have mandated the teaching of creation-science
in the public schools of Arkansas. Overton's decision followed an extraordinary
public trial in which a series of scientific heavyweights, including Harvard's
Steven J. Gould, persuasively argued in court that "creation-science"
was a religious idea that did not meet the generally-accepted tests for
scientific theory. As such, the Arkansas creation-science law had the primary
effect of advancing a religion in the public schools, and was invalidated
under the First Amendment's clause prohibiting establishment of religion.
A similar law in Louisiana was invalidated shortly thereafter. Case closed?
Not at all.
There is a new movement to counter the teaching of evolution in the schools, and it claims to be based on a non-religious critique of evolution. In many respects, the anti-evolution crusades of the 80s may have failed because they were aimed too high at State Boards of Education and Legislatures. The public pressure was obvious, easily recognized, and quickly invalidated by court orders and scientific counterattacks. This time the opponents of evolution have targeted a campaign at the grassroots at local school boards and it looks like they are having some success.
In September of 1993, an anti-evolution majority of newly elected board of education members in Vista, California voted to implement a "creation-science" component as part of their biology curriculum. The science teachers of the district were critical of the decision, and their textbook selection committee flatly rejected a book put forward to support anti-evolution teachings. Backing down only slightly, the elected local board has now instructed the schools to include "discussions of divine creation " at "appropriate times" in the social science and language arts curricula. Similar actions have been urged upon scores of school boards around the country, and in some places, challenges to evolution are already part of the standard curriculum. Since 1986, for example, the school board of Louisville, Ohio, has directed its teachers to teach "alternate theories to evolution" The centerpiece of these challenges to evolution is something that has become known as "intelligent design theory."
Intelligent design has been embraced by critics of evolution around the country who are eager to find an seemingly non-religious alternative to the teaching of evolution. Intelligent design is the modern synthesis of a classic argument that an engineer would love. Quite simply, it states that living organisms are the product of careful and conscious design. A close examination of living organisms, so the argument goes, reveals details of structure and physiology that cannot be accounted for by the workings of evolution. Therefore, these organisms must be the products of design.
The Argument from Design
If you were walking through the woods, and saw two objects lying on the ground, a stone and a pocket watch, what would your first thoughts be? Suppose a companion asked you where the stone and the pocket watch had come from? You might well have laughed as you answered that for all you knew, the stone had been there forever. It's safe to say, however, that you would not have given that answer concerning the watch. It could not have been there forever, for the very simple reason that it was produced by a watch-maker, and watch-makers have not existed forever. Every gear, spring, and screw in a watch is evidence of the fact that watches are not natural objects that have existed forever. Rather, they have been produced by the conscious design and handiwork of watch-makers.
In 1802, Rev. William Paley of Carlisle made that argument in his book Natural Theology. As you might suspect, watches and stones were not the real objects of his interest, for Paley was concerned with a timeless question that still rivets our attention nearly two centuries later. With all of its astonishing variety, complexity, and diversity, did life itself have a designer? To Paley, the answer was clear.
... "There cannot be design without a designer; contrivance without a contriver ... The marks of design are too strong to be got over. Design must have had a designer. That designer must have been a person. That person is GOD. "
Paley's writings form one of the most lucid examples of a train of reasoning known as the "Argument from Design." In various forms, it has served for centuries as a classic argument for the existence of God, and more recently, as a counter-argument for a very different explanation of the diversity of living species. That alternative explanation was advanced more than 50 years after Paley by his countryman, Charles Darwin. Darwin's "abstract" of his work, On the Origin of Species, was an instant scientific and popular sensation. The theory of evolution, as Darwin's ideas have come to be known, accounts for the origin of living species in ways that could not be more different from those of William Paley. In Darwin's world, living things did not have a conscious, intelligent designer. Instead of being designed, their exquisite adaptations and specializations were the products of natural selection, acting on the raw materials of variation and genetic change.
Paley's argument for conscious design was well known to Darwin, and he answered it effectively, showing that natural selection could account for many of the classic examples of structures and organs that were thought to demand conscious design. But Darwin did not put the argument from design to rest. Far from it. The modern advocates of this argument now clamor for a place in the science classroom under the banner of "intelligent design theory." In fact, a modern restatement of the argument is found in the book Of Pandas and People by Percival Davis & Dean Kenyon. This well-illustrated 170 page text is the very book rejected by Vista's science teachers in 1993. Despite this recent setback, Of Pandas and People is often put forward as an example of how intelligent design might be placed in the biology classroom.
The book argues that "In creating a new organism, as in building a new house, the blueprint comes first. We cannot build a palace by tinkering with a tool shed and adding bits of marble piecemeal here and there. We have to begin by devising a plan for the palace that coordinates all the parts into an integrated whole. Darwinian evolution locates the origin of new organisms in material causes, the accumulation of individual traits. That is akin to saying the origin of a palace is in the bits of marble added to the tool shed. Intelligent design, by contrast, locates the origin of new organisms in an immaterial cause: in a blueprint, a plan, a pattern, devised by an intelligent agent. "
Of all the arguments that have been advanced against evolution, intelligent design is the most appealing, most common, and in my view, the most effective. The reasons should be obvious. First, the argument is easy to make and easy to understand. Second, the argument appeals to the emotional sense that we, and other living things, are what we are and where we are as the conscious result of intelligent design. Third, and most telling, the argument seems strengthened by each advance in our understanding of the complexity of life. The grander the palace, the greater the leap of imagination that is required to imagine that it could have been constructed by "tinkering with a tool shed."
I would not argue, even for a minute, that living organisms are not complex or intricate. In fact, I'd claim that even William Paley underestimated the complexity of living organisms by several orders of magnitude. One case in point is a structure often cited as a perfect example of intelligent design: the human eye. Indeed, the eye is often compared to a camera, but such comparisons are unfair. The eye is better than any camera.
Like a top-of-the-line modern camera, the eye contains a self-adjusting aperture, and an automatic focus system. Like a camera, its inner surfaces are surrounded by dark pigment to minimize the scattering of stray light. However, the sensitivity range of the eye, which gives us excellent vision in bright sunlight as well as in the dimmest moonlight, far surpasses that of any film. The neural circuitry of the eye produces automatic contrast enhancement and sensitivity to motion. Its color analysis system enables it to quickly adjust to lighting conditions (incandescent, fluorescent, and sunlight) that would require a photographer to change film or add filters.
Finally, the eye-brain combination produces depth perception that is still beyond the range of an camera or video system. Just ask your local photo or video engineer to design a system that will calculate, from a snapshot, the exact force required to sink a basket, on the run, from 25 feet away. Charles Barkley and his NBA colleagues perform such calculations with astonishing regularity, all based on the information that their eyes acquire in a split second glance at the basket.
The argument from design asserts that the combination
of nerves, sensory cells, muscles, and lens tissue in the eye could only
have been "designed" from scratch. It would be too much, the argument
goes, to ask evolution, acting on one gene at a time, to assemble so many
interdependent parts. After all, how could evolution start with a sightless
organism and produce a retina, which would itself be useless without a lens,
or a lens, which would be useless without a retina? As Paley himself wrote:
"Is it possible to believe that the eye was formed without any regard
to vision; that it was the animal itself which found out, that, although
formed with no such intention, it would serve to see with?"
Complex physiological systems are not the only cases to which the argument from design can be applied. One might well ask whether the careful and precise movements of cells and tissues during human embryonic development do not argue for the role of intelligent design, rather than evolution, in the formation of the structures of a new human life. The intricacies of the human genome, with its 6 billion base pairs of DNA encoding an estimated 100,000 genes, can also be taken as an argument for intelligent design. Proponents of intelligent design often compare the DNA sequence of the genome to a computer program, powerful and flexible and carefully designed. Surely the chance forces of evolution could not assemble so much purposeful complexity, and surely the very sequences of human DNA argue for intelligent design.
Evolution as a Creative Force
Intelligent-Design advocates content that evolution could not have produced such complex structures and processes because its instrument, natural selection, simply isn't up to the tast. Such advocates agree that natural selection does a splendid job of working on the variation that exists within a species. Given a range of sizes, shapes, and colors, those individuals whose characteristics give them the best chance to reproduce will pass on traits that will increase in frequency in the next generation. The real issue, therefore, is whether or not the "input" into genetic variation, which is often said to be the result of random mutation, can provide the beneficial novelty that would be required to produce new structures, new systems, and even new species. Could the marvelous structures of the eye have been produced "just by chance?"
The simple answer to that question is "no." The extraordinary number of physiological and structural changes that would have to appear at once to make a working, functioning eye is simply too much to leave to chance. The eye could not have evolved in a single event. That, however, is not the end of the story. The real test is whether or not the long-term combination of genetic variation and natural selection could indeed produce a structure as complex and well-adapted as the eye, and the answer to that question is a resounding "yes."
The pathway by which evolution can produce such structures has been explained many times, most recently in Richard Dawkins' extraordinary book, The Blind Watchmaker. The essence of Dawkins' explanation is simple. Given time (thousands of years) and material (millions of individuals in a species), many genetic changes will occur that result in slight improvements in a structure or system. However slight that improvement, so long as it is a genuine improvement, natural selection will favor its spread throughout the species over several generations.
Little by little, one improvement at a time, the system becomes more and more complex, eventually resulting in the fully-functioning, well-adapted organ that we call the eye. The retina and the lens did not have to evolve separately, because they evolved together. As Dawkins is careful to point out, this does not mean that evolution can account for any imaginable structure, which may be why living organisms do not have biological wheels, X-ray vision, or microwave transmitters.
But evolution can be used as an explanation for complex structures, if we can imagine a series of small, intermediate steps leading from the simplex to the complex. Further, because natural selection will act on every one of those intermediates, these intermediate steps cannot be justified on the basis of where they are going (the final structure). Each step must stand on its own as an improvement that confers an advantage on the organism that possesses it.
Evolution of the eye: A complex eye could easily have evolved from a simple eyespot through a series of minor and reasonable variations. When a change conferred even a slight advantage, it would have spread throughout the population over several generations.
This step-by-step process is the real reason why
it is unfair to characterize evolution as "mere chance," even
though chance plays a role in it. The continuing power of natural selection
fine-tunes each stage of the process in a way that is not determined by
chance. Can we apply this step-by-step criterion to a complex organ like
the eye? Yes, we can, quite easily in fact. We can begin with the simplest
possible case, a small animal with a single light-sensitive cell. We can
then ask, at each stage, whether natural selection would favor the incremental
changes that are shown, knowing that it if would not, the final structure
could not have evolved, no matter how beneficial.
Starting with the simplest light-sensing device, a single photoreceptor cell, it is easy to draw a series of incremental changes that would lead, step-by-step, directly to lens-and-retina eye. None of the intermediate stages requires anything more than an incremental change in structure: an increase in cell number, a change in surface curvature, a slight increase in transparency. Therefore, all the changes are reasonable.
The critic might ask what good that first tiny step, perhaps only 5% of an eye, might be. As the saying goes, in the land of the blind, the one-eyed man is king. In a population with limited ability to sense light, every slight improvement is favored, even if it represents only 5% of an eye. If each individual, incremental change would be favored by natural selection, the whole sequence is would be favored as well. Since none of the steps involves an unreasonable genetic change, the contention that evolution cannot explain the evolution of a complex eye is refuted.
One might rightly claim, of course, that if this were really true, then evolution should have driven the independent development of light-sensing abilities in scores of organisms. Has it? In their 1992 review of the evolution of vision, Michael F. Land and Russell D. Fernald cite evidence that primitive eye-spot light-sensing systems have evolved independently as many as 65 times, and that more complex image-forming systems have evolved many times, employing roughly 10 optically distinct image-formation mechanisms. In the mollusks alone, distinct light-sensing systems exist that bear an uncanny resemblance to each of the stages in our hypothetical scheme. Obviously, each of these intermediates has to be considered reasonable if an organism living today possesses it.
If we can account for the evolution of complex structures by incremental advances, this might seem to leave us with no way to distinguish design from evolution. Evolution, then, might have produced such structures. But did it? In fact, there is a way to tell. Evolution, unlike design, works by the modification of pre-existing structures. Intelligent design, by definition, works fresh, on a clean sheet of paper, and should produce organisms that have been explicitly (and perfectly) designed for the tasks they perform.
Evolution, on the other hand, does not produce perfection. The fact that every intermediate stage in the development of an organ must confer a selective advantage means that the simplest and most elegant design for an organ cannot always be produced by evolution. In fact, the hallmark of evolution is the modification of pre-existing structures. An evolved organism, in short, should show the tell-tale signs of this modification. A designed organism should not. Which is it?
The eye, that supposed paragon of intelligent design, is a perfect place to start. We have already sung the virtues of this organ, and described some of its extraordinary capabilities. But one thing that we have not considered is the neural wiring of its light-sensing units, the photoreceptor cells in the retina. These cells pass impulses to a series of interconnecting cells that eventually pass information to the cells of the optic nerve, which leads to the brain. Given the basics of this wiring, how would you orient the retina with respect to the direction of light? Quite naturally, you (and any other designer) would choose the orientation that produces the highest degree of visual quality. No one, for example, would suggest that the neural wiring connections should be placed on the side that faces the light, rather than on the side away from it. Incredibly, this is exactly how the human retina is constructed.
What are the consequences of wiring the retina backwards? First, there is a degradation of visual quality due to the scattering of light as it passes through layers of cellular wiring. To be sure, this scattering has been minimized because the nerve cells are nearly transparent, but it cannot be eliminated, because of the basic flaw in design. This design flaw is compounded by the fact that the nerve cells require a rich blood supply, so that a network of blood vessels also sits directly in front of the light-sensitive layer, another feature that no engineer would stand for. Second, the nerve impulses produced by photoreceptor cells must be carried to the brain, and this means that at some point the neural wiring must pass directly through the wall of the retina. The result? A "blind spot" in the retina, a region where thousands of impulse-carrying cells have pushed the sensory cells aside, and consequently nothing can be seen. Each human retina has a blind spot roughly 1 mm in diameter, a blind spot that would not exist if only the eye were designed with its sensory wiring behind the photoreceptors instead of in front of them.
Do these design problems exist because it is impossible to construct an eye that is wired properly, so that the light-sensitive cells face the incoming image? Not at all. Many organisms have eyes in which the neural wiring is neatly tucked away below the photoreceptor layer. The squid and the octopus, for example, have a lens-and-retina eye quite similar to the vertebrate one, but these mollusk eyes are wired right-side-out, with no light-scattering nerve cells or blood vessels above the photoreceptors and no blind spot.
None of this should be taken to suggest that the eye functions poorly. Quite the contrary, it is a superb visual instrument that serves us exceedingly well. To support the view that the eye was produced by evolution, one does not have to argue that the eye is defective or shoddy. Natural selection, after all, has been fine-tuning every organ in the body, including the vertebrate eye, for millions of years. The key to the argument from design is not whether or not an organ or system works well, but whether its basic structural plan is the obvious product of design. The structural plan of the eye is not.
Evolution, which works by repeatedly modifying preexisting structures, can explain the inside-out nature of the vertebrate eye quite simply. The verterbate retina evolved as a modification of the outer layer of the brain. Over time, evolution progressively modified this part of the brain for light-sensitivity. Although the layer of light-sensitive cells gradually assumed a retina-like shape, it retained its original orientation, including a series of nerve connections on its surface. Evolution, unlike an intelligent designer, cannot start over from scratch to achieve the optimal design.
Tinkering with Success: the Mark of Evolution
The living world is filled with examples of organs and structures that clearly have their roots in the opportunistic modification of a preexisting structure rather than the clean elegance of design. Steven Jay Gould, in his famous essay "The Panda's Thumb," makes exactly this point. The giant panda has a distinct and dexterous "thumb" which, like our own thumb, is opposable. These animals nimbly strip the leaves off bamboo shots by pulling the shoots between thumb and their five other fingers. Five? No, the panda doesn't have six fingers, because it's thumb isn't a true digit at all. In fact, it grips the shoot of bamboo between its palm and a bone in the wrist which, in giant pandas, has been enlarged to form a stubby protuberance.
A true designer would have been capable of remodeling a complete digit, like the thumb of a primate, to hold the panda's food. Evolution, on the other hand, settled for much less: a bamboo-gripping pseudo-digit that conferred just enough of an advantage to be favored by natural selection. As Gould himself notes, a single mutation increasing the rate of growth of this wristbone could explain the formation of the Panda's "thumb." Natural selection itself explains how this simple modification was advantageous. It is a clear case of the way in which evolution produces organisms that are well-adapted, but not necessarily well-designed.
A true designer could begin with a clean sheet of paper, and produce a design that did not depend, as evolution must, on re-using old mechanisms, old parts, and even old patterns of development. The use of old developmental patterns is particularly striking in human embryonic development. The early embryos of reptiles and birds, which produce eggs containing massive amounts of yolk, follow a particularly specialized pattern of development. This pattern enables them to produce the three vertebrate body layers in a disc of cells that sits astride a hugh sphere of nutritive yolk. They eventually surround that yolk with a "yolk sac," a layer of cells that supplies the embryo with nutrition from the stored yolk.
Placental mammals produce tiny eggs, so there would be no need to follow a developmental pattern that surrounds the non-existent mass of yolk. Nevertheless, as Scott F. Gilbert, the author of an influential book on developmental biology notes:
"What is surprising is that the gastrulation movements of reptilian and avian embryos, which evolved as an adaptation to yolky eggs, are retained even in the absence of large amounts of yolk in the mammalian embryo. The inner cell mass can be envisioned as sitting atop an imaginary ball of yolk, following instructions that seem more appropriate to its ancestors."
Indeed, human embryos even go so far as to form an empty yolk sac, surrounding that non-existent stored food. The human yolk sac develops from the same tissues as the yolk sacs of reptiles and birds, performs many of the same functions (except, of course, for using the non-existent yolk), and gives rise to the same adult tissues. That it why it has been known as a "yolk sac" for more than a century. The cells of the sac channel nutrients to the embryo (much as they do in birds and reptiles), and play a role in the formation of the circulatory, reproductive, and digestive systems. These functions do not explain, however, why the cells that perform them should take the form of a sac.
There is no reason, from the standpoint of intelligent design, for the human embryo to produce an empty yolk sac. Evolution, of course, can supply the answer. If placental mammals are descended from egg-laying animals, like reptiles, then the empty yolk sac can be understood as a evolutionary remnant. The yolk sac is produced by a process of development that could not be re-designed simply because mammalian eggs had lost their yolk. It suggests that mammals evolved from animals that once had eggs with large amounts of yolk. Does the historic fossil record support that contention? Absolutely. The very first recognizable mammals in the fossil history of life on Earth are known by a telling name: they are the "reptile-like mammals."
Hints of the Past
The concept of intelligent design is particularly clear on one point: organisms have been designed to meet the distinct needs of their lifestyles and environments, not to reflect an evolutionary history. Is this distinction between evolution and design testable? I think it is, and the test is a simple one. Intelligent design dictates that the genetic system of a living organism should be constructed to suit its present needs, and should not contain superfluous genes or gene sequences that obviously correspond to structures or substances for which the organism has no need. In short, the master genetic plan should correspond precisely to the organism for which it codes.
No living bird has teeth, and that fact, of course, is behind the old saying that a rare object is "as scarce as hen's teeth." Why don't birds have teeth? A proponent of intelligent design must answer that they have not been designed to have teeth, quite probably because the designer equipped them with alternatives (hard beaks and food-grinding gizzards) that are superior for lightweight flying organisms.
Is this in fact the case? In 1980 Edward Kollar and his colleague C. Fisher decided to test whether or not chicken cells still have the capacity to become teeth. Intelligent design would predict that they cannot, because teeth were never designed into the organism.
Kollar & Fisher's experiment was simple. They took mouse tissue that normally lies just beneath the epithelial cells that develop into teeth, and put it in contact with chick epithelial cells. What happened? The chick cells, apparently influenced by the mouse tissue, dutifully began to develop into teeth. The produced impact-resistant enamel on their surfaces, and developed into clear, recognizable teeth (Figure 5). The experimenters took great care to exclude the possibility that mouse tissue had produced the teeth, first by making sure that no mouse epithelium was included in the experiments, and second by confirming that the cells in the tooth-producing tissue were indeed chick cells. Their experiments have since been confirmed by two independent groups of investigators.
No plan of intelligent design can account for the presence of tooth-producing genes in chicken cells. Indeed, it would be remarkably un-intelligent to endow birds with such useless capabilities. Evolution, on the other hand, has a perfectly good explanation for these capabilities. Birds are descended from organisms that once had teeth, and therefore they may retain these genes, even if other genetic changes normally turn their expression off. In short, birds have a genetic mark of their own history that no designed organism should ever possess. Designed organisms, after all, do not have evolutionary histories.
The Story in DNA
In today's world, it is possible to test evolution and intelligent design as never before. Rather than depending upon the indirect evidence of structure and physiology, we can go right to the source to the genetic code itself. If the human organism is, indeed, the product of careful, intelligent design, a detailed analysis of human DNA should reveal that design. Remember the quotation from Of Pandas and People: "We cannot build a palace by tinkering with a tool shed and adding bits of marble piecemeal here and there. We have to begin by devising a plan for the palace that coordinates all the parts into an integrated whole." We can test intelligent design simply by examining the genome to see if it matches the prediction of a coordinated, integrated plan.
If, on the other hand, the human genome is the product of an evolutionary history, that DNA should be a patchwork riddled with duplicated and discarded genes, and loaded with hints and traces of our evolutionary past. This, too, can be tested by directly examining the coded sequences of human DNA.
Although a complete sequence for all human DNA is at least a decade away, we already know more than enough of that sequence to begin to address the question of design. Let's take, as a representative example, a piece of chromosome # 11 known as the b -globin cluster. About 60,000 DNA "bases" are in the cluster, each base effectively representing 1 letter of a code that contains the instructions for assembling part of a protein. b -globin is an important part of hemoglobin, the oxygen-carrying protein that gives blood its red color. There are 5 different kinds of b -globin, and the cluster contains a gene for each one .
Why are there so many different forms of the b -globin gene? Here both evolution and intelligent design could supply an answer. Two of the genes are expressed in adults, and the other three are expressed during embryonic and fetal development. Evolution maintains that the multiple copies have arisen by gene duplication, a random process in which mistakes of DNA replication resulted in extra copies of a single ancestral gene. Once the original b -globin gene had been duplicated a number of times, so the explanation goes, slight variations within each sequence could produce the 5 different forms of the globin gene.
Why would different forms of b -globin be useful? The embryo, which is engaged in a tug-of-war for oxygen with its mother, must have hemoglobin that binds oxygen more tightly than the mother's adult hemoglobin. The 3 versions of the gene that are expressed during embryonic development enable hemoglobin to do exactly that. These slight variations enable embryonic blood to draw oxygen out of the maternal circulation across the placenta into its own circulation. Hence, gene duplication provided a chance for special forms of the b -globin gene to evolve that are expressed in fetal development.
Intelligent design proposes much the same mechanism, except that the production of extra copies and their modification to suit the embryo were a matter of intentional design, not chance and natural selection. Intelligent design maintains that the DNA sequences of each of the 5 genes of the cluster are matters of engineering, not random gene duplications fine-tuned by natural selection. So which is it? Are the 5 genes of this complex the elegant products of design, or a series of mistakes of which evolution took advantage?
The cluster itself, or more specifically a sixth b -globin gene, provides the answer. This gene is easy to recognize as part of the globin family because it has a DNA sequence nearly identical to that of the other five genes. Oddly, however, this gene is never expressed, it never produces a protein, and it plays no role in producing hemoglobin. Biologists call such regions "pseudogenes," reflecting the fact that however much they may resemble working genes, in fact they are not.
How can we be sure the sixth gene really is a pseudogene? Molecular biologists know that the expression of a gene like b -globin is a two-step process. First, the DNA sequence has to be copied into an intermediate known as RNA. That RNA sequence is then used to direct the assembly of a polypeptide, in this case, a b -globin. There is no evidence that the first step ever takes place for the pseudogene. No RNA matching its sequence has ever been found. Why? Because it lacks the DNA control sequences that precede the other 5 genes and signal the cell where to start producing RNA This means that the pseudogene is "silent." Furthermore, even if it were comehow copied into RNA, it still could not direct the assembly of a polypeptide. The pseudogene contains 6 distinct defects, any one of which would prevent it from producing a functional polypeptide. In short, this sixth gene is a mess, a nonfunctional stretch of useless DNA.
From a design point of view, pseudogenes are indeed mistakes. So why are they there? Intelligent design cannot explain the presence of a nonfunctional pseudogene, unless it is willing to allow that the designer made serious errors, wasting millions of bases of DNA on a blueprint full of junk and scribbles. Evolution, however, can explain them easily. Pseudogenes are nothing more than chance experiments in gene duplication that have failed, and they persist in the genome as evolutionary remnants of the past history of the b -globin genes.
The b -globin story is not an isolated one. Hundreds of pseudogenes have been discovered in the 1 or 2% of human DNA that has been explored to date, and more are added every month. In fact, the human genome is littered with pseudogenes, gene fragments, "orphaned" genes, "junk" DNA, and so many repeated copies of pointless DNA sequences that it cannot be attributed to anything that resembles intelligent design.
If the DNA of a human being or any other organism resembled a carefully constructed computer program, with neatly arranged and logically structured modules each written to fulfill a specific function, the evidence of intelligent design would be overwhelming. In fact, the genome resembles nothing so much as a hodgepodge of borrowed, copied, mutated, and discarded sequences and commands that has been cobbled together by millions of years of trial and error against the relentless test of survival. It works, and it works brilliantly; not because of intelligent design, but because of the great blind power of natural selection to innovate, to test, and to discard what fails in favor of what succeeds. The organisms that remain alive today, ourselves included, are evolution's great successes.
A Process Set in Motion
It is crucial to recognize the stakes of this debate. "Intelligent design theory" requires that we pretend to know less than we do about living organisms and that we pretend to know less than we do about design, engineering, and information theory. It demands that we set aside evolution's simple and logical explanations for the design flaws of living organisms in favor of a nebulous theory that pretends to account for everything by stating "well, that's the way the designer made it." In short, it requires a retreat back into an unknowledge of biology that is unworthy of the scientific spirit of this century.
It is particularly unfortunate that the advocates of intelligent design theory seem to see it as a way of countering what they view as evolution's inherent incompatibility with religion. In reality, evolution is not at all inconsistent with a belief in God, a fact recognized by Darwin himself in the concluding passage of Origin of Species:
"There is grandeur in this view of life, with its several powers, having been originally breathed by the Creator into a few forms or into one; and that. whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been and are being evolved."
William Paley once hoped that the study of life could tell us something about the personality of the creator. Although Paley was wrong about the argument from design, he may have been right about the issue of personality. It seems to me that the scope and scale of evolution can only magnify our admiration for a creator who could set such a process in motion. To the deeply religious, evolution may not be seen as a challenge, but rather as proof of the power and subtletly of the creator's ways. The great Architect of the universe might not have written down each DNA base of the human genome, but He would still be a very clever fellow indeed.