The Edge of Evolution
Page 18
It’s one thing to say that both Windows and Apple operating systems require formatting, and that they both have programs for copying, editing, and deleting computer code. It’s quite another to say either that the codes arose by unintelligent processes, or even that Apple formatting could be switched to Windows formatting by a series of beneficial, random changes. Big changes in Moby Dick—duplicating chapters, rearranging paragraphs and sections—won’t convert it into a new story any more than will small changes, such as spelling changes or duplicating or deleting single words. Monkeys typing on computers equipped with even the most advanced word-processing features still can’t generate coherent changes to a text—only intelligence can. Shapiro makes a strong case that the genome is much more sophisticated than had been thought, and that changes in repetitive DNA can affect an organism. But if anything he is pointing the way to a possible mechanism for the unveiling of a designed process of common descent. Something must control this process; it cannot be random.
In fact, old-fashioned Darwinism demonstrably has more going for it than rival unintelligent theories. Self-organization and self-engineering played no visible role in the evolution of malaria and HIV over the past fifty years. Whatever the many shortcomings of Darwin’s theory, small random mutations and natural selection do seem to account perfectly well for the resistance of malaria to chloroquine and of HIV to various drugs. On the other hand, in a hundred billion billion chances, there have been no apparent occasions where unintelligent-but-non-Darwinian processes have helped much—no sudden changes to new cellular states, no massive rearrangements by the genome reengineering itself. The only hint of non-Darwinian events in the best studies of evolution is found in Richard Lenski’s work with E. coli.16 He reported that “insertion sequences” (DNA sequences resembling viruses that can hop around a genome) do cause many mutations, which often break and disrupt genes. Yet none of them make new cellular structures. The fact that natural genetic engineering processes are indeed quite active, as Lenski and others have shown, yet malaria and HIV have made no good use of them in 1020 tries, strongly suggests they have very limited utility.
Indeed, the work on malaria and AIDS demonstrates that all possible unintelligent processes in the cell—both ones we’ve discovered so far and ones we haven’t—at best have extremely limited benefit, since no such process was able to do much of anything. It’s critical to notice that no artificial limitations were placed on the kinds of mutations or processes the microorganisms could undergo in nature. Nothing—neither point mutation, deletion, insertion, gene duplication, transposition, genome duplication, self-organization, self-engineering, nor any other process as yet undiscovered—was of much use. Darwinism helped the parasites a little bit, so it takes the prize for the best of the unintelligent mechanisms. But any other putative non-Darwinian, unintelligent processes were undetectable. It’s reasonable to conclude, then, that all other unintelligent processes are even less effective than Darwinism.
DARWIN MEETS MICHELSON-MORLEY
P. falciparum, HIV, and E. coli are all very, very different from each other. They range from the simple to the complex, have very different life cycles, and represent three different fundamental domains of life: eukaryote, virus, and prokaryote. Yet they all tell the same tale of Darwinian evolution. Single simple changes to old cellular machinery that can help in dire circumstances are easy to come by. This is where Darwin rules, in the land of antibiotic resistance and single tiny steps. Burning a bridge that can stop an invading army or breaking a lock that can slow a burglar are easy and effective. But if just one or a few steps have to be jumped to gain a beneficial effect, as with chloroquine resistance, random mutation starts breathing hard. Skipping a few more steps appears to be beyond the edge of evolution.
There is much evidence from these studies that, in their incoherent flailing for short-term advantage, Darwinian processes can easily break molecular machinery. There is no evidence that Darwinian processes can take the multiple, coherent steps needed to build new molecular machinery, the kind of machinery that fills the cell.
Yet if it can do so little, why is random mutation / natural selection so highly regarded by biologists? Because the dominant theory requires it. There is ample precedent in the history of science for the overwhelming bulk of the scientific community strongly believing in imaginary entities postulated by a favored theory. For example, in the nineteenth century physicists knew that light behaved as a wave, but a wave in what? Ocean waves travel through water, sound waves through air; what medium do light waves travel through as they traverse space from the sun to the earth? The answer, announced with the utmost confidence by James Clerk Maxwell, the greatest physicist of the age, was the “aether” (that is, “ether”).17
Whatever difficulties we may have in forming a consistent idea of the constitution of the aether, there can be no doubt that the interplanetary and interstellar spaces are not empty, but are occupied by a material substance or body, which is certainly the largest, and probably the most uniform body of which we have any knowledge. (emphasis added)
In his article “Ether,” published in the Encyclopedia Brittanica in the 1870s for all the world to read, the eminent Maxwell simply voiced the shared certainty of the entire physics community: Light was a wave, a wave needed a medium, the medium was called ether. In the encyclopedia article Maxwell not only proclaimed the existence of the ether, he precisely calculated its density and coefficient of rigidity! But in 1887 Albert Michelson and Edward Morley conducted a now-classic experiment to discern the presence of the ether, and found absolutely nothing. No trace of the “essential” substance. Whether the physicists’ theories needed it or not, no ether could be detected.
Just as nineteenth-century physics presumed light to be carried by the ether, so modern Darwinian biology postulates random mutation and natural selection constructed the sophisticated, coherent machinery of the cell. Unfortunately, the inability to test the theory has hampered its critical appraisal and led to rampant speculation. Nonetheless, although we would certainly have wished otherwise, in just the past fifty years nature herself has ruthlessly conducted the biological equivalent of the Michelson-Morley experiment. Call it the M-H (malaria-HIV) experiment. With a billion times the firepower of the puny labs that humans run, the M-H experiment has scoured the planet looking for the ability of random mutation and natural selection to build coherent biological machinery and has found absolutely nothing.
Why no trace of the fabled blind watchmaker? The simplest explanation is that, like the ether, the blind watchmaker does not exist.
OVER THE EDGE
All unintelligent processes give very limited benefit. It’s at this point in the book, then, that we must plunge across the boundary of Darwinian evolution to ponder what lies beyond. On this side of the edge of evolution lie random mutation and natural selection. On the other side—what?
First, it’s certainly reasonable to suppose that natural selection plays a large role on both sides. After all, by itself natural selection is an innocuous concept that says only that the more fit organisms will tend to survive. Such a truism pretty much has to be operative in almost any biological setting. The big question, however, is not, “Who will survive, the more fit or the less fit?” The big question is, “How do organisms become more fit?” Or (now that we know much more about the molecular foundations of life) the question is, “Where did complex, coherent molecular machinery come from?” Even for that big question, the answer almost certainly will involve natural selection (at least after something has been supplied for natural selection to favor).
But just as certainly the answer will not involve random mutation at the center. From our best relevant data—parasitic diseases of humanity—we see that random mutation wreaks havoc on a genome. Even when it “helps,” it breaks things much more easily than it makes things and acts incoherently rather than focusing on building integrated molecular systems. Random mutation does not account for the “mind-boggling” sys
tems discovered in the cell.
So what does? If random mutation is inadequate, then (since common descent with modification strongly appears to be true) of course the answer must be non random mutation. That is, alterations to DNA over the course of the history of life on earth must have included many changes that we have no statistical right to expect, ones that were beneficial beyond the wildest reach of probability. Over and over again in the past several billion years, the DNA of living creatures changed in salutary ways that defied chance.
What caused DNA to change in nonrandom, helpful ways? One can envision several possibilities. The first is bare chance—earth was just spectacularly lucky. Although we have no right to expect all the many beneficial mutations that led to intelligent life here, they happened anyway, for no particular reason. Life on earth bought Powerball lottery ticket after lottery ticket, and all the tickets simply happened to be grand prize winners. The next possibility is that some unknown law or laws exist that made the cellular outcomes much more likely than we now have reason to suppose. If we eventually determine those laws, however, we’ll see that the particular machinery of life we have discovered was in a sense written into the laws. A third possibility is that, although mutation is indeed random, at many critical historical junctures the environment somehow favored certain explicit mutations that channeled separate molecular parts together into coherent systems. In this view the credit for the elegant machinery of the cell should go not so much to Darwin’s mechanism as to the outside world, the environment at large.
Each reader must make his own judgments about the adequacy of these possible explanations. I myself, however, find them all unpersuasive. Although much more could be said, briefly my reasons are these. The first possibility—sheer chance—is deeply unsatisfying when invoked on such a massive scale. Science—and human rationality in general—strives to explain features of the world with reasons. Although serendipity certainly plays its part in nature, advancing sheer chance as an explanation for profoundly functional features of life strikes me as akin to abandoning reason altogether. The second and third possibilities both seem inadequate on other grounds. They both seem in a sense to be merely sweeping the problem of the complexity of life under the rug. The second possibility replaces the astounding complexity of life with some unknown law that itself must be ultracomplex. The third possibility simply projects the functional complexity of life onto the environment. But, even in theory, neither the second nor third possibilities actually reduce complexity to simplicity, as Darwin’s failed explanation once promised to do.
Instead, I conclude that another possibility is more likely: The elegant, coherent, functional systems upon which life depends are the result of deliberate intelligent design. Now, I am keenly aware that in the past few years many people in the country have come to regard the phrase “intelligent design” as fighting words, because to them, the word “design” is synonymous with “creationism,” and thus opens the door to treating the Bible as some sort of scientific textbook (which would be silly). That is an unfortunate misimpression. The idea of intelligent design, although congenial to some religious views of the universe, is independent of them. For example, the possibility of intelligent design is quite compatible with common descent, which some religious people disdain. What’s more, although some religious thinkers envision active, continuing intervention in nature, intelligent design is quite compatible with the view that the universe operates by unbroken natural law, with the design of life perhaps packed into its initial set-up. (In fact, possibilities two and three listed above—where nonrandomness was assigned either to complex laws or to the environment—can be viewed as particular examples of this. I think it makes for greater clarity of discussion, however, just to acknowledge explicitly in those cases that the laws or special conditions were purposely designed to produce life.)
In the remainder of the book, I’ll plainly treat the other side of the edge of evolution as the domain of design. Readers who strongly disagree with design may take it simply as showing how the design argument is framed, or just as showing how little Darwinian processes explain and how much is not understood. Readers who are open to design explanations can see how well it fits with other aspects of nature that science has recently uncovered.
SURVIVOR
What is the rational justification for chalking up to design features of life that may be just barely over the edge of evolution, such as molecular systems that contain two different cellular protein-protein binding sites? After all, up until now I have shown simply that it was biologically unreasonable to think that Darwinian processes produced them. How do we proceed from the improbability of Darwinism to the likelihood of design?
Let’s consider an analogy. Imagine that, like Tom Hanks in Cast Away, you wash up on a tropical island, the sole survivor of a plane crash. Choking and spitting out water, you pull yourself up off the sand and set off to explore the island, to look for food and shelter. After hours walking along the beach catching crabs, you turn and head for the interior mountains, hoping to find a cave to use as a base. Eventually you stumble across a sizeable crevice in the side of a mountain where you can at least take cover from storms. Over the next few weeks you range farther and farther on the large island, finding some coconut trees here and other edible plants there.
One day while exploring a distant stony beach you notice a half dozen football-sized rocks close together, forming a small crescent. Odd. But there are a lot of rocks around and they have to be in some pattern, so why not a crescent? About fifty yards away on the edge of the same beach you find another group of rocks, roughly the same size as the first, but this group has a couple dozen rocks and forms a complete circle, about four feet in diameter; no other rocks are close by. Very odd. Maybe a freak accident. Maybe a larger rock got hit by lightning, shattering it into pieces that landed in a circle, or possibly a swirling wave pushed rocks into a circle.
A week or two later while exploring the jungle, you spot a banana tree. Overjoyed at the prospect of a new food source you continue in the same direction, hoping to find a few others. During a ten-minute walk you find some more banana trees, a few scattered—then six of them, in two rows of three, each spaced about a dozen feet apart. Strange. Why should they grow like that? Were there just three original trees that happened to be growing in a row, and then perhaps a steady wind blew seeds perpendicular to the row? Or maybe there were two original trees, and the wind blew seeds to make two rows of three? But what sort of a lucky wind would it take to space the seeds so evenly?
A little farther into the jungle you find a grove of thirty-five mango trees in five neat rows of seven. About a quarter mile from the grove you discover a square of stone walls, with four straight sides ten feet long, each with three layers of stone neatly atop each other. Running now, you surmount a hill and for the first time spy the other side of the island. On the far beach, broken and weathered, are the remains of a small sailing vessel, a hundred years old by the looks of it. Its mast is snapped, planks are missing from the hull, and only shreds of the sail remain.
After rummaging through the ship, you walk back to your cave, and again pass the banana and mango groves, the square of rocks, and the circle and crescent. Now you see them differently. Did the wind blow seeds into neat rows of fruit trees, or did a shipwrecked sailor plant them? How about those piles of stones? Not just the big square, but the circle and the crescent, too? Once it’s crystal clear that some things on the island—the ship and its contents—are the result of intelligent design, you have to reevaluate other features of the island. Now possible explanations include not only nature and luck, but mind and purpose, too.18 Yet how do you decide if something is more likely accounted for by intelligence rather than the natural forces that also are at play on the island?
Here’s one way. Design is the purposeful arrangement of parts.19 Rational agents can coordinate pieces into a larger system (like the ship) to accomplish a purpose. Although sometimes the purpose of the sys
tem is obscure to an observer who stumbles upon it, so the design goes unrecognized,20 usually the purpose can be discerned by examining the system. What’s more, the arrangement of the pieces is frequently one that is quite unlikely to occur by chance. So if something on the island now looks as if it might have served some palpable objective, and if it seems quite unlikely to be the result of chance, you decide that the best explanation may be that it was purposely arranged that way.
With those considerations in mind, you now judge that the mango grove is very likely to have been purposely planted. The purpose would be to provide a supply of food, and the probability of the mango trees’ growing in five neatly spaced rows of seven seems quite low. However, although suspicious-looking, the two rows of banana trees might just be a coincidence. Flukes do happen, even when an intelligent agent is around, so it’s hard to tell for sure. The crevice in the mountain you are using as a base is not an uncommon natural occurrence—no reason to suspect design there. The square, three-layered stone pile is presumptively an incomplete or dismantled makeshift shelter; the four-foot circle of rocks is most probably some old campsite, rather than the aftermath of a lightning strike. But instead of a second campsite where some of the rocks were washed away, the small crescent of rocks might really be a fortuitous arrangement. After all, there are a lot of other rocks around, and some simple pattern or other might pop up just by chance.
You would make inferences based on your experience of the likelihood of some event happening by chance. You might be wrong in some cases, when your estimation is off. What’s more, new evidence (such as discovering that the crescent is actually part of a large circle of rocks—a second campsite—the rest of which were covered by sand) could affect a conclusion, just as the new evidence of the discovery of the ship affected your judgments. Your level of confidence in design for different cases could range widely, from sneaking suspicion to utter certainty. As the estimated probability of serendipity decreases and the clarity of the purpose of the arrangement increases, your confidence in design would also increase. The stone crescent may be a fluke; the makeshift shelter almost certainly isn’t. The wrecked ship itself, never.