Quantcast

Root and Branch | The Nation

  •  

Root and Branch

  • Share
  • Decrease text size Increase text size

First the bright side. The anti-Darwin movement has racked up one astounding achievement. It has made a significant proportion of American parents care about what their children are taught in school. And this is not a question of sex or salacious novels; the parents want their children to be taught the truth. None of your fancy literary high jinks here, with truth being "relative." No, this is about the real McCoy.

About the Author

Ian Hacking
Ian Hacking, the author of The Taming of Chance and other books, is an honorary professor at the Collège de...

According to a USA Today/Gallup poll conducted this year, more than half of Americans believe God created the first human beings less than 10,000 years ago. Why should they pay for schools that teach the opposite? These people have a definite and distinct idea in mind. Most of the other half of the population would be hard-pressed to say anything clear or coherent about the idea of evolution that they support, but they do want children to learn what biologists have found out about life on earth. Both sides want children to learn the truth, as best as it is known today.

The debate about who decides what gets taught is fascinating, albeit excruciating for those who have to defend the schools against bunkum. Democracy, as Plato keenly observed, is a pain for those who know better. The public debate about evolution itself, as opposed to whether to teach it, is something else. It is boring, demeaning and insufferably dull.

The arguments that Darwin painstakingly presented in On the Origin of Species by Means of Natural Selection, or The Preservation of Favoured Races in the Struggle for Life (1859) were revolutionary in their day. They continue to astonish and perplex; never take them for granted. Unfortunately, anti-Darwinism keeps playing minor variations on the same negative themes and adds nothing to our understanding of life. Many scientists who are upset by the ongoing lobbying insist that it is bad science or pseudo-science. Living With Darwin, Philip Kitcher's brief and cogent manifesto, very rightly disagrees. Anti-Darwinism is, he says, dead science, recapitulating old stuff long abandoned. I prefer to call it degenerating.

I take the word from Imre Lakatos, a philosopher of science who liked to flaunt the aphorisms "Every theory is born refuted" and "Every theory wallows in a sea of anomalies." Both exaggerations have been true of evolutionary theories from the word go, but evolution has gone from strength to strength. Lakatos was a great rationalist, but following his hero Karl Popper, he did not think that theories are good when they are established as true. His unit of evaluation was the research program rather than the theory. A rational program is, he said, "progressive" in that it constantly reacts to counterexamples and difficulties by producing new theories that overcome old hurdles. When challenged it does not withdraw into some safe corner but explains new difficulties with an even riskier, richer and bolder story about nature. Degenerate programs paint themselves into smaller and smaller corners, skirting problems they'd prefer not to face. They seldom or never have a new, positive explanation of anything. In short, they teach us nothing.

There is no one philosophy of science that fully accounts for the evolving body of practices we call the sciences. I would not want to apply Lakatos's model indiscriminately. It is a colorful way to point to the difference between the history of evolutionary biology since Darwin and anti-Darwin posturing that explains nothing. Anti-Darwinism is not pseudo-science or even dead science so much as degenerate science--and that, in pretty much the explicit sense, I owe to Lakatos.

The Discovery Institute, a conservative think tank, states that "neo-Darwinism" posits "the existence of a single Tree of Life with its roots in a Last Universal Common Ancestor." That tree of life is enemy number one, for it puts human beings in the same tree of descent as every other kind of organism, "making a monkey out of man," as the rhetoric goes. Enemy number two is "the sufficiency of small-scale random variation and natural selection to explain major changes in organismal form and function." This is the doctrine that all forms of life, including ours, arise by chance. Never underestimate the extraordinary implausibility of both these theses. They are, quite literally, awesome.

The tree of life is one of our most ancient metaphors, recurring and profound. There it is in Eden, firmly planted in Genesis 2:9. It was initially free for all, unlike the infamous tree of knowledge, which grew beside it. Much earlier it was carved in stone on Assyrian monuments. The menorah is a tree with seven branches. The cross itself is a tree of life: Made from the wood of dead trees, it became the symbol of eternal life.

We have been working out uses for tree pictures forever. Family relationships were represented by trees in the sixth century. Genealogical trees had to wait another 300 years. But then the Tree of Jesse, showing the ancestry of Christ, grew into vivid displays on medieval glass and illustrated texts. In the eighteenth century Linnaeus and his fellow naturalists classified species and genera of plants in a hierarchical way that can lend itself to representation by a tree. Nineteenth-century Victorians were obsessed with family trees, perhaps because the prosperous ones were worried that their interlocking marriages made their pedigrees all too close to incestuous. One of those gentlemen, Charles Darwin, put it all together: "All true classification is genealogical; that community of descent is the hidden bond which naturalists have been unconsciously seeking."

A genealogical tree of life thereby became the symbol of the theory of evolution by natural selection. We used to rely on the shapes of organisms and their parts in order to construct an ancestral tree. We now use molecular genetics to trace relations. Four years ago Richard Dawkins, Darwin's eloquent though abrasive champion, announced that by 2050 we should have completed "the one true tree of life, the unique pattern of evolutionary branchings that actually happened." That is exactly what sticks in the craw of all those who doubt the theories that descend from Darwin.

I myself take the tree of life in Genesis as a wonderful intimation of things to come. Like all the ancient commentators, I read it as allegory. Those who read it as revealed truth should see that it laid out the road to follow, right from the start, in human speculation about the mysteries and miracles of life. Those who think that Genesis is just another old book should marvel that its authors got it right, in the very beginning, planting the tree of life in the human mind.

Not surprisingly, the central chapter of Kitcher's book is "One Tree of Life." He does an exemplary job of showing how apt the metaphor is, as a way of representing knowledge about the origin of the species. Nevertheless, it is useful to reflect on difficulties in the present, rather than successes in the past. They arise precisely because the evolutionary program is "progressive" in Lakatos's sense. Anti-Darwinists love to repeat news of difficulties. They say, "We told you so; it is just a bunch of guesswork." Hence defenders of the faith, like Kitcher, do not like to dwell on present problems, for fear of giving succor to the foe.

I wonder if they should not instead celebrate the difficulties, making plain that evolutionary theory is a living, growing, vital organism, while anti-Darwinism is lifeless, if not, in Kitcher's word, dead. In my opinion the arrogant religion-baiters--yes, Richard Dawkins comes to mind, but others are worse--do a disservice to their cause by making evolutionary theory seem so cut and dried (viz. dead), when it is a blooming, buzzing, confusing delight, finding out more about the world every day. With anti-Darwinians fabricating a "controversy," it helps to see what a real scientific controversy is like, with each competing conjecture piling on new research methods, new explanations, new questions, new failures and new successes.

It is, for example, splendidly difficult to draw a definitive tree of life. I shall mention just two open questions. First, man and monkey. Kitcher well explains that at the species level, chimpanzees are the closest, genetically, to humans. But it is not wholly clear how to put gorillas, chimpanzees and humans on a tree. On balance, at present, the most probable tree has species X splitting into gorillas on one branch and species Y on another; species Y splits into chimps and people. But some molecular evidence suggests that X splits into Y and chimps, with Y splitting into gorillas and people. Another tree suggested by other molecular evidence is X evolving into Y and humans, with Y evolving into gorillas and chimps. A paper in Nature in 2006 proposed an unusual resolution to the conundrum: Early on, there was a lot of hybridization between humans and chimpanzees!

The DNA record does not give us a tidy tree because it encodes a lot of slightly different evolutionary histories in kindred animals, covering a very short span of recent time. With gorillas, chimps and humans we are talking no more than 8 million years. We may not end up with a tree even for the part that most interests us, the one on which humans hang. A thicket or bush, yes, but a clean-limbed tree, perhaps not. Thus the old question of the missing link has been transformed into a series of new questions that have immeasurably added to our understanding and leave us asking for more. That is the mark of a progressive research program.

There is a deep reason underlying the difficulty just mentioned. The ideas of species, genera and the rest of the taxa are invaluable in practical botany, ecology, the fisheries, etc., for sorting living organisms as they are now. Classes of living things really are distinct. But historically they are on a continuum. The species, as distinct and definite entities, fade away. I am no expert on Darwin, but it seems to me that he saw this very clearly.

When, thanks to Darwin, we turned from classification at a time to classification over time in the long haul, species began to drop out except as a convenient way to distinguish bits of the fossil record and match them with present life-forms. Because of the depth of the tree idea in the human mind (yes, back to Genesis and beyond), we have been fixated on the project of arranging definite species, like fruit, on a tree of descent. To exaggerate, there are no historical species to hang with exactitude. Not even our own, which we narcissistically call Homo sapiens (Latin for "wise man"). Anyone who reads Origin will notice that Darwin displayed only one curiously abstract tree diagram in that book. Starting in 1866, Ernst Haeckel, Darwin's great advocate in Germany, began to cover pages with exuberant trees of descent, including the first drawn tree of animal evolution. It is as if we have been trying to imitate Haeckel, but Darwin was the wiser man.

The human genome does have an incredible amount of historical information that we have only just begun to decode. Genetic anthropology is the liveliest of the human sciences today. It uses molecular biology to track the movements of peoples across the globe. It is a fabulous continuation of the program begun in another of Darwin's great books, The Descent of Man (1871). At the end of May this year, an enormous Creation Museum and Family Discovery Center opened near Cincinnati; innocent children are told that "The first man walked with dinosaurs and named them all!"

Perhaps we had better not speak of tree diagrams but of tree-ish diagrams or, to be Latinate, arborescent diagrams, as being the upshot of Darwin today. Even so--and here is my promised second open question--the representation of life on such diagrams may work well only for human-sized organisms: roughly speaking, from whales to mites, redwoods to lichen. Even that is misleading: Once we get down to fungi, classification is a mess. The action in evolutionary research today is, however, far below that, at the bacterial level. One fascinating idea is horizontal (or lateral) gene transfer. Bacteria, which don't have sex, probably pass genetic material from one to another, quite indifferent to who is descended from whom--from one species of bacterium to another. This idea was first circulated by C.R. Woese in 1977, and it has blossomed into a vigorous research program. By 2000 Scientific American had published a popular essay, "Uprooting the Tree of Life." It could be that the earliest life-forms had distinct origins; these then shared genetic material by passing it sideways, making life as a whole a bit more viable on a nasty planet. No unique primal ancestor after all.

Some biologists are pretty skeptical and doubt that horizontal transfer, if it exists, is a big deal. More radical souls are guessing that even mites and lichen benefit from horizontal transfer, via bacteria. (And maybe that's the problem with fungi.) You can sensibly take bets either way. I would bet that what we find out about bacteria in the next decade, including horizontal gene transfer, will wonderfully enrich our understanding of life and its origins. I might be ignorantly backing the wrong horse. Evolutionary theories are rich in open questions. That is what makes them so exciting.

Contrast that with pseudo-controversy and take, for example, Michael Behe, a professor at Lehigh University who must be the most ingenious and prolific anti-Darwinian biologist at work today. My use of "anti-Darwin" follows him. Unlike Ronald Numbers or Michael Lienesch, I do not speak of the antievolution movement or of creationism. This is because Behe says, in effect, "Sure, I believe in evolution by natural selection--it just doesn't do all it is supposed to." In his capacity as a biologist he does not officially argue for special acts of creation. So you cannot call him antievolution or creationist. But he is undeniably anti-Darwin. His first book was Darwin's Black Box (1996). His latest book is The Edge of Evolution: The Search for the Limits of Darwinism. The label "anti-Darwin" seems the right umbrella term for creationism, antievolutionism--and Behe.

In his first book, Behe makes his case against evolutionary theory by taking up the eye argument. Even Aristotle was astonished by the eye, whose parts developed together so that an animal could see. After 1859 people asked how all the parts could have evolved before the survival value of seeing was in place. Behe applies the argument to a question about the complex devices that enable bacteria to get around. (Kitcher summarizes this quite well.) If you like, Behe has raised the number of open questions about evolution from a million to a million and one. We now know quite a lot about the eye, but we are only just beginning to figure out bacterial evolution. So it is a good bet that his problem will stay around for a while. But that is not scientific controversy. There is no give and take of explanation and counterexample, no new methodology, no new anything--just the same old question dressed up in slightly new clothes.

The same is true of Behe's new book, which restates the "not enough time for evolution to work" objection. That arose when we were debating the age of the earth, 140 years ago. Behe looks at examples such as the retrovirus associated with AIDS, in which new generations appear every few minutes, a chance for the evolution of the retrovirus to hurtle ahead. It does not, or so he argues (not too convincingly, to my mind, but leave that aside). Maybe he has increased the number of open questions to a million and two. Once again, we get a recycled objection in slightly new packaging, and no new ideas. It reminds us of the degeneracy of anti-Darwins. Can't they do better than that? Apparently not.

Theories of evolution have been evolving ever since Jean-Baptiste Lamarck began lecturing on the subject in 1800. "Founder of the evolutionary theory," it says on his grand statue at the entry to the botanic gardens in Paris. That is a good reminder that Darwin, marvelous thinker and naturalist that he was, is only part of an ongoing story. The pedigree of evolution passes through Darwin's natural selection, through the synthesis with Mendel's genetics, through the idea of mutation--but also through the statistician's observation that you can get a lot of speciation without mutation, by sheer combinatorial chance, called genetic drift. Perhaps horizontal gene transfer will be established in a future history of evolutionary thought. It is already a commonplace of biotechnology. We used to cross strains of cattle to produce the breeds we are familiar with. Fine animals in farm fairs have pedigrees that can be as neatly drawn as a family tree. But today entire kingdoms are crossed: Fish genes are put into tobacco plants to help them resist disease. Thus the end twigs on the tree of life are being grafted to one another with consequences that cannot be foreseen. Genetically modified organisms are here to stay. A new and very untreelike chapter in evolutionary history is unrolling before our eyes.

Kitcher's long final chapter addresses a pressing question that is seldom asked. Why, when we are bathed in the innumerable implausible and often incomprehensible results of modern science, is Darwin the bogeyman? A short version of Kitcher's answer is that we need the consolations of religion, and they are untenable in the light of Darwin. And why does anti-Darwinism thrive only in America? Because life there is so cruel and competitive, says Kitcher, that Americans need extra consolation.

I simplify, but I found his discussion too simplistic. We have to summon sociologists and historians to point the way. Why has anti-Darwinism thrived in the United States for almost a century? How has it been so successful? Until 1918 the United States was much like the rest of the industrialized world. After some initial bickering and pious rethinking after 1859, an evolutionary account of life was taken for granted. The age of the earth and natural selection were accommodated by all of the churches that took notice of such topics. That's how it is with religions: They evolve to fit their contemporary worlds. Every expert and most interested lay people knew there were endless problems in the Darwinian research program, but the overall project was accepted. Science and Christianity made their peace.

Then something happened. A series of twelve pamphlets called The Fundamentals was printed in Chicago, from 1910 to 1915. After the First World War ended, the "fundamentalists"--those touting The Fundamentals--pushed anti-Darwinism and became a major intellectual and political force in America. The movement has had its ups and downs since then, but with an astounding run of ups. Fifteen years ago Ronald Numbers published an encyclopedic history of the phenomenon. He told of the initial hostility to the theory of natural selection, followed by its almost universal acceptance by the end of the nineteenth century; and then The Fundamentals, followed by vehement public denunciation of evolution. Numbers has now updated his history, The Creationists, with two chapters about intelligent design. He has thus written a great reference work but does not fully address the how and why questions. Michael Lienesch tries to do so, using contemporary methodology for studying social movements and agenda-setting.

The general message can be summed up by twisting a line from Edison. The success of anti-Darwinism has been 1 percent inspiration and 99 percent perspiration--endless committee work, backroom organizing and networking to support the preaching. The successes are not in any way accidental or inspirational. Anti-Darwinists have been well funded. Three million copies of The Fundamentals were mailed in their first five years. The heartland in the beginning was not, as is so often imagined, a rural backwater. It was very often Chicago businessmen whom Numbers and Lienesch identify, men taking time out from building the great traditional corporations that Chicago gave to the world, or from commanding the skyscrapers that continue to astonish tourists. The Moody Bible Institute, granddaddy of them all, sits at the corner of LaSalle Drive and Chicago Avenue. When I was a child in a Canadian public school, I avidly watched its extraordinary nature movies about life and growth; they gave us a break from the teachers. Snatches of them have stayed with me the rest of my life as an atheist.

Lienesch is essential reading for anyone who wants to understand the successive waves of anti-Darwinism, right up to intelligent design. Kitcher, as I said, reflects on why Americans need God. He mentions the moving story of a noted agnostic scholar who found comfort in a great New York cathedral, after she had learned that her child would soon die of a horrible disease. A cathedral? Somehow, that is a giveaway. Kitcher's background is Episcopalian (mine, too, for my sins). I think he is just not down to earth enough when he turns to the abiding strengths of religion. I'd like to say his heart is in the right place, unlike the current crop of atheist propagandists, but the trouble is that, as with many Episcopalians, it is more mind than heart. (It takes one to know one.)

As a foreign kibitzer, I would like to repeat what I said at the start about democracy. Movements need perspiration and organization, but they also need uptake by the people. I have no use for anti-Darwinian campaigners, but I do have a lot of respect for popular skepticism. The people do not trust those who present themselves as elite. If you want a sense of the monstrous self-confident complacency of days gone by, read H.L. Mencken's daily reports to the Baltimore Sun on the Scopes trial, now reissued under the title A Religious Orgy in Tennessee. Or read any of the self-indulgent, virulent atheists in circulation today--Sam Harris and Christopher Hitchens being just two. Contrary to their professed intentions, such writers buttress the faithful; their loathsome arrogance shields evangelical churches from doubt. That part of the American population that believes God made man in His own image has a heartfelt contempt for know-it-alls. I am inclined to say, God bless the people, even when they get it wrong.

I have said nothing about the second sticking point for the anti-Darwin movement, that chance variation and natural selection have sufficed to produce the living world as we know it. It is an incredible doctrine. Darwin himself was pretty cautious about it. I respect anyone who says he cannot believe it. But that is where one should stay, in a state of disbelief. Once you start arguing against it, you end up being silly.

Intelligent design is silly. It is a refurbished version of the argument advanced at the end of the seventeenth century and the beginning of the eighteenth by those I call Royal Society divines--important Anglican clergymen, often fellows of the Royal Society of London, the leading scientific institution of the day. The argument at its most concise is known as Bishop Paley's pocket watch. If you found something like a watch in the desert, you would of course suppose it was an artifact of an intelligent watchmaker. Here we find ourselves in an intricate world that we think of as an elaborate mechanism, so there must be an intelligent worldmaker.

The argument had predecessors: that there must be a creator because there is an obvious purpose in the world. That is called the teleological argument, which goes back to antiquity and which is Thomas Aquinas's "Fifth Way" to God. Kant and Hegel thought it the sole rational consideration of merit. But only the English, obsessed by machines, tried to construct an argument based specifically on the fact that the world appears to be very well and intricately designed, a pocket watch on a universal scale. (The "argument from design" is a pretty standard part of American freshman or sophomore philosophy courses, but there is not even a name for it in France, where it seems at best, well, sophomoric.)

There is a problem with the argument, including its most up-to-date versions: It says nothing about the designer. At the end of the teleological argument, the Fifth Way, we learn about the purpose in the world, and purpose requires an agent. Having established a purposeful agent who creates, an Aquinas can exclaim, "And this Being can be only Thou, O Lord!" That does not come so easily at the end of an argument from design. So the world must have a brilliant engineer, a molecular engineer at that, a veritable nanotechnologist. Why think this being has anything to do with any god, Christian or other?

There is the trite ad hominem observation, repeated by Kitcher, that quite a few aspects of the design, even of humans, seem rather imperfect; a reasonably good engineer could have done better. The nasty cynic says, "Why not an absolutely evil genius as designer?" So we get an argument for the existence of the devil at work.

An amused cynic is more fun. Life seems the handiwork of a mad designer, who fits several DSM diagnoses from the American Psychiatric Association. He--only a male would do this--is obsessed with intricate details so long as they do not get too much in the way of other devices he concocts. For example, he designs and builds a bird such as the Arctic tern (Sterna paradisaea, apt name, that), which annually migrates in a figure-eight pattern across the North and South Atlantic from the Arctic to the Antarctic and back. Brilliant, brilliant design, a navigation system with two routes from pole to pole, sturdy enough to survive earth's cruelest seas--all madly miniaturized in a brain the size of a plum. But why on earth, were it not for a lunatic fascination with design itself? A proof, thus, that the earth with its denizens is the work of a crazed design-freak.

This silly cynicism invites a more attractive thought. Leibniz proposed that the actual world is the one that combines the maximum of variety with the minimum of complexity for its fundamental laws. The "best" world, the world sought by the most intelligent designer, is one that maximizes variety in its phenomena and simplicity of basic law. Such a world has no place for a specific set of plans for the Arctic tern. The upshot is not attractive to those who favor intelligent design. It is in effect a proof that we live in a world of quantum-mechanical laws that are counterintuitive (to humans) but intrinsically simple--a world that, once these laws are in place, is then allowed to evolve out of a very few raw materials by chance and selection into unendingly complex patterns, including life on earth as we know it. It is a fact that you will get complex structures if you just let such systems run.

The wisest designer would choose the governing laws and initial conditions that best capitalized on this mathematical fact. A stupid designer would have to arrange for all the intricate details (the Arctic tern again) that anti-Darwinians eulogize, but an intelligent designer would let chance and natural selection do the work. In other words, in the light of our present knowledge, we can only suppose that the most intelligent designer (I do not say there is one) would have to be a "neo-Darwinian" who achieves the extraordinary variety of living things by chance.

  • Share
  • Decrease text size Increase text size