Second Genesis

"The logical climax of evolution can be said to have occurred," said the man in the white coat, "when, as is now imminent, a sentient species deliberately and directly assumes control of its own evolution."

The man was Dr. John Heller, director of the New England Institute for Medical Research. He paced his office, paused to rap a pointer on the green chalkboard where he had drawn a diagram of a chromosome, stepped back from the board and folded his arms. "Yes," he said, gazing at the diagram, "imminent." Ten years ago, such a statement might (continued on page 148)Second Genesis(continued from page 117) have been made by a mad doctor in a science-fiction movie. Five years ago, it was mumbled in a timid and indirect way by a few scientists who were known in academic circles and, with these words, became famous—for talking before thinking. Today, it is the kind of thing that almost any biologist, chemist, botanist or geneticist might be expected to say. It is said not only in the privacy of offices but before audiences at scientific conventions, in scholarly journals and in university classrooms. It is said directly, with no hedging, no "conceivably" or "it has been suggested." It is just said.

In the opinion of many scientists—not all, but an articulate many—the logical climax of evolution is here. Man, the sentient species of a small planet circling a small sun in a dim backwater of the galaxy, is about to undertake the breathtaking adventure of re-creating himself. By tinkering with the mechanisms of his heredity, he plans to improve on nature's designs. He believes he can learn to change any part of his body's engineering: his susceptibility to disease, his height and intelligence and beauty, the very span of his life. After two billion years of evolution by trial and error, we now stand at the beginning of humankind's next phase: the Second Genesis.

"How will you choose to intervene in the ancient designs of nature for man?" asked biophysicist Robert Sinsheimer last year in the Bulletin of the Atomic Scientists. "Would you like to control the sex of your offspring? It will be as you wish. Would you like your son to be six feet tall? Seven feet? Eight feet? What troubles you? Allergy? Obesity? ... These will be easily handled .... Even the timeless patterns of growth and maturity and aging will be subject to our design. We know of no intrinsic limits to the life span. How long would you like to live?"

Dr. Sinsheimer is not a man given to hyperbole. He is a professor at the California Institute of Technology, a scientist who commands world-wide respect for his work on the atomic structure of living cell components. The bulletin in which he wrote these words is a sober, rather ponderous journal of scholarship.

"Yes, certainly this kind of thing is hard to believe," says Professor Charles Price of the University of Pennsylvania. "All through history men have felt that 'life' was something only nature or God could tinker with. It was mysterious, undiscoverable. But now we're finding that it isn't: It's only chemistry. Extremely complex chemistry." Dr. Price, who was president of the American Chemical Society in 1965, raised smoke that year when he urged that the study of genetic processes—and specifically the attempt to create artificial life in the laboratory—be made a national crash program with the same priorities as NASA's man-on-the-moon project. "If we can take dead materials and make a living thing out of them," he says, "we'll have shown dramatically, once and for all, that life is not a mystical phenomenon beyond the reach of science. Can we do it? It may already have been done, depending on your definition of 'life.' It will soon be done unequivocally. I tell my students that I count on a fifty-fifty chance of seeing it in my lifetime [Dr. Price is 54] and that I'm sure they'll see it in their lifetime."

He pauses. "I got in trouble for saying this last year," he adds after a while, "but I'm prepared to go on saying it. The political, social, biological and economic consequences of such a breakthrough would dwarf those of either atomic energy or the space program."

The stuff behind all these grand, eloquent and destiny-shaking prophecies is a group of chemicals called nucleic acids, better known by their abbreviations: DNA (deoxyribonucleic acid—the master chemical) and RNA (ribonucleic acid—the subsidiary or message-carrying chemical). These chemicals exist in living cells and they have captured the imaginations of biological scientists. The enormously long, coiled, springlike molecules of DNA seem to be the main pattern holders of heredity. Each such molecule is apparently built of thousands of subunits, lined up in precise order like numbers on a tape. The numbers seem to form a code of "words"; and the words, translated into action by complex chemical processes that aren't yet fully understood, tell each living cell what to be, how to grow, what substances to produce with what raw materials handled in what ways.

You began life as a single cell containing DNA contributed in equal proportions by your mother and your father. This tiny bit of nucleic acid (about six trillionths of a gram) told the cell that it was to multiply in such a way as to produce a human being. The DNA in an acorn tells it how to become an oak tree. Not only are nucleic acids apparently the repositories of genetic blueprints, they are also the basic organizers and controllers of all life processes, from the relatively simple metabolism of an amoeba to (most scientists presume) the last and most complex process yet to evolve: human intelligence. Nucleic-acid molecules give you and the amoeba and the oak tree that elusive quality called "life." They are the tiny but tangible foundations of the state of being alive.

In their tangibility lies their fascination. "The state of aliveness was once intangible," says biochemist Dr. Paul Saltman of the University of California at San Diego, "and an intangible thing or condition doesn't lend itself to scientific study. Now molecular biology has made the basic life process tangible. We can study it. If we can study it, we're arrogant or foolish enough to believe we can understand it eventually. And if we can understand it, we can tinker with it, control it, maybe produce it artificially. And if we can do these things—well, you see what the excitement is about."

The excitement of the 1960s is the culmination of a scientific detective story that goes back to the 19th Century. In 1866, the Austrian monk Gregor Mendel, studying hereditary patterns of pea plants in a monastery garden, set forth the idea that genetic information is carried from parent to offspring in discrete units, which were later called genes. Each gene carries a specific piece of information needed to build the offspring.

Researchers after Mendel determined that the genes somehow resided in and worked through the chromosomes, dark sausage-shaped bodies in the nuclei of cells. A chromosome was an actual, physical thing that could be seen under a microscope; but a gene was still only an abstract idea, a convenient word that could be used in predicting whether a baby would be blond or dark. Scientists could watch through microscopes while chromosomes (23 in each human sperm and egg) divided and recombined; but the precise mechanism by which the parents' genetic information was carried into the baby and translated into the proteins and other components of his living form was a total mystery. In fact, it was so much a mystery that many scientists thought life must be governed by laws all its own and couldn't profitably be studied in terms of physics and chemistry as we knew them.

A few years after Mendel published his historic theory, a German named Friedrich Miescher, while breaking plant and animal cells down to see what they were made of, found an unfamiliar substance in the cell nuclei. He called it nuclein. Chemists after him renamed it nucleic acid. Further studies of nucleic acid in the early 1900s enabled scientists to break it down more specifically. They added the prefixes ribo- and deoxyribo- to describe chemically the two varieties of nucleic acid. For a long time, nobody knew the purpose of these nucleic acids. Then, in the mid-Twenties, a chemist named Robert Feulgen showed that DNA is found almost exclusively inside the cell nucleus. A Belgian biochemist, Jean Brachet, further narrowed the inquiry when he discovered that DNA could be found only in the chromosome. Other pieces of evidence followed one by one. In the 1940s, French and American scientists added an important new clue. They found that, in any given species of living thing, the amount of DNA in every cell is exactly the same—with one significant exception. Sperm and egg cells have precisely half the amount carried in other cells. When a sperm and an egg get together, they fuse into a single cell, add their half complements of DNA to make a full amount and thus start the life of a new man or mouse or bumblebee.

It now seemed likely that the nucleic acids were the physical embodiment of Mendel's abstract genes. The clincher came in 1944 from the Rockefeller Institute in New York. A scientific team changed the hereditary traits of bacteria by soaking them in a bath containing DNA from different bacteria. This famous experiment proved beyond much doubt that DNA is the basic repository of genetic blueprints.

In the two decades since then, the problem has been to find out exactly how the genetic mechanisms work. The problem looked so huge in the early 1950s that discouraged biologists were tempted to say it was virtually insoluble. One biologist at Princeton University, pondering the complexity of a human adult with roughly a trillion cells, concluded that the necessary blueprints would fill more books than were contained in his university's cavernous library. But breakthroughs came. Among the most important was the proposal in 1953 of a double-helical (picture two intertwined circular staircases) model of DNA's molecular structure by James D. Watson and Francis H. C. Crick. Watson, who was 25 at the time, has recently told the story of the discovery in The Double Helix, a uniquely bold, personal account of the ambition, comradeship and infighting among the modern breed of Nobel Prize seekers. With Crick and a third researcher, Watson got his Prize—the ultimate scientific honor—in 1962. The breakthroughs have in large part been due to the fact that biologists have been joined by reinforcements of men from other fields—atomic physicists, polymer chemists—all lured by the fascinating prospect of uncovering life's last secrets. New designations have been invented to indicate this crossbreeding of disciplines: biophysics, biochemistry, molecular biology. The search for answers is so single-minded that it cuts clear across not only scientific but also national boundaries. It isn't unusual at a biochemists' convention to find Americans, Germans, Russians and Red Chinese gathered around a table, stuttering excitedly in one another's languages as they try to pass information and theories back and forth.

How does DNA work? Trying to understand parts of the process one by one, scientists today routinely perform heredity-changing experiments like the original one in 1944. At the New England Institute, for instance, Dr. Heller is studying the action of nucleic acids in a certain type of fungus. The fungus normally grows white, but one mutant strain is pink. He and his colleagues carefully extract and purify nucleic acids from the cells of the pink strain. These nucleic acids contain faulty genetic instructions—in effect, a misprinted word or words somewhere in the code—that make the mutant strain's cells handle certain chemical processes in an erroneous way and so produce an abnormal color. With a miniature needle, under a microscope, the scientists inject a strong dose of this genetic material into the nucleus of a normal fungus cell. Then they put the cell in a bath of nutrients and let it go on with its business of living. It absorbs nutrients and processes them as its genetic instructions dictate. It turns pink. The faulty instructions have superseded the cell's original ones.

When the cell divides, the faulty instructions are passed on to its daughter cells. They, too, are pink. So are all their progeny after them. Eventually, a mature fungus plant is formed—a mutant, all of its cells are pink. When it reproduces by means of spores, the spores carry the faulty instructions with them. All the new young fungi are also pink. Thus, a full-scale permanent mutation has been caused artificially.

"But not wholly artificially," Dr. Heller points out. "We use DNA that was made by nature, not by us. The dream is to take DNA and doctor it deliberately so as to cause some specific, desired change in the genetic instructions. The ultimate dream is to do this with human DNA and change Homo sapiens into Homo superior. So far, we've taken only the first few steps on that long, long road."

Before genetic instructions can be changed deliberately and specifically, it will be necessary to know precisely what the DNA code says and how it is translated into living flesh. This is a complicated task. The basic building materials of all living things are proteins, and all proteins are made from combinations of 20 amino acids. There are literally hundreds of thousands of possible ways in which these amino-acid molecules can be arranged in space and hooked together so as to form a protein molecule. "The problem is twofold," says Roy Avery, of the American Chemical Society. "Number one: Find out how all the relevant proteins are built. Number two: Find out what words in the DNA code specify each protein and how the specifications are carried out."

But the job has been started. Dr. Marshall Nirenberg at the National Institutes of Health, Dr. H. Gobind Khorana of the University of Wisconsin and other researchers in Germany, Japan and Russia have now all but cracked the first stage of the code. They know what DNA code words seem to specify what amino acids—though there are still some puzzling ambiguities in the code that remain to be understood. Dr. Khorana's approach has been to make synthetic, highly simplified nucleic acids whose molecular subunits are arranged so as to spell the same word over and over again. These are, in effect, simple man-made genes. He puts such a word in a "cell-free protein synthesizing system"—essentially, a bath of amino acids, enzymes and other chemicals such as are found in the protein-making sites of a living cell. Guided by the nucleic-acid code word, the system manufactures a simple protein. Dr. Khorana then analyzes the protein to see which amino acid or acids are incorporated in it. He and others who are traveling this route find that, with some still-puzzling exceptions, a given code word always specifies the same amino acid. Other researchers using natural instead of synthetic nucleic acids corroborate the finding. One code word evidently means one amino acid throughout all of nature—in man, mouse, oak tree or amoeba (strong support for the theory that all life on earth is descended from common ancestors).

But there is more to life than merely manufacturing proteins. There are also complicated regulatory functions. Each creature has its characteristic shape, size, intelligence. How are these encoded in the genetic material? Granted that DNA and RNA can direct the making of protein, how do they know how much to make, at what times, in what parts of the body?

One man who is studying these questions is Professor Clement Markert, chairman of the biology department at Yale University. You began life, he points out, as a single cell. Contained in it were the complete plans for making you as you are today. That original cell divided geometrically into two, four, eight, until you were a small amorphous blob of cells, all precisely alike, all containing the same plans. But as you continued to develop, the cells began to take different chemical routes. By the time you were hauled yowling into the daylight, you contained many diverse kinds of cells: muscle, bone, liver, brain, etc.

Dr. Markert wants to know how this is regulated. At what point in fetal development does a hitherto "undifferentiated" cell decide that it is going to be a liver cell, and what makes it thenceforth ignore all the genetic instructions for making bone or brain or eye tissue?

Professor Markert says there is a mechanism for switching genes on and off at certain times in certain cells. The DNA in a liver cell seems to be the same as in every other cell in the same body; but in that particular cell, the genes for making and maintaining bones and eyes and everything else but the liver are apparently switched off. This can be illustrated with frog embryos. It's possible to separate dozens or theoretically thousands of cells from a single young embryo, put them in a nutrient bath and grow a tadpole from each of them—a process much like the common horticultural system of cloning, or asexually reproducing, plants. But if you try this trick with cells from a more fully developed embryo or an adult frog, the clones won't live—presumably because some of the cells' genes have by now been switched off and no single cell any longer has a complete set of usable frog plans.

Trying to figure out how such a chemical switching system might work, Professor Markert has whittled the problem to manageable size by concentrating on one simple enzyme made by all vertebrate cells. The enzyme, lactate dehydrogenase (needed for efficient use of oxygen), is made of two kinds of subunits that various cells put together in five different proportions. "The assumption is that two genes are needed to make this enzyme," says Dr. Markert. "In some cells, one gene is 'turned on' more than the other; in other cells, both genes are turned on equally. Is there a feedback system to tell the genes when they've made the right proportions and when they should turn on and off? Can they be artificially influenced to turn on and off at the wrong times? If we can answer these questions, we may have some valuable clues about the ways in which genes are regulated."

This is the kind of research that is going on right now. It is research that, to many scientists, heralds the coming of the Second Genesis.

"Some of the predictions you hear scientists make today may seem farfetched," says Dr. Charles Price. "In reality, they are no more so than were predictions about nuclear energy—which were laughed at in 1930." The predictions deal with the grand concept of genetic engineering.

For if scientists can understand how the genetic mechanism works, they can presumably learn to tune it or supercharge it or even rebuild it from scratch. If they can find what part of the code says "high intelligence," for example, they can conceivably rearrange the molecular structure or add new units so as to say "still higher intelligence." With this knowledge, they can cause deliberate mutations in the human species.

A mutation might be engineered in much the same way as it's engineered today in that pink fungus—perhaps through direct injections of nucleic acid into a man's or a woman's reproductive cells or into a single sperm or egg. The mutation would then start with the progeny. Or a mutation might be made to start in the adult himself, biochemist E. L. Tatum of Rockefeller Institute has suggested, by means of artificial viruses.

A virus is an odd small creature that may not, in fact, be a creature at all. It is simply a tiny package of nucleic acid in a protein shell. Drifting about in air or water, it neither grows nor ages, nor reproduces, nor does anything else lifelike. It comes to something like "life" when it breaks into a living cell of a man, an animal or a plant. Once inside the cell, it releases an enzyme that, in effect, partially blanks out the cell's own genetic instructions. Professor Sol Spiegelman of the University of Illinois, discoverer of this enzyme, calls it "replicase." The cell, flooded with replicase, thenceforth begins to process materials in accordance with the virus' genetic plans instead of its own. The cell obediently makes new viruses, which spread into other cells of the host and repeat the process.

This superimposing of wrong genetic instructions may damage the host—as in human viral diseases such as polio, pneumonia, influenza and perhaps some kinds of cancer. On the other hand, a viral infection can be benign. We may have hundreds of viruses in our cells that we don't know about, simply because the cells can manage to go on with their own genetic business while making viruses part time. It may be, in fact, that some desirable human mutations have been accidentally caused by viruses at various times in man's 2,000,000-year history. And it is conceivable that genetic scientists can learn to make viruses on order, so as to cause specific new mutations.

Professor Spiegelman has already made artificial viruses in his Illinois lab. He first accomplished the feat in 1965. He mixed up a chemical broth that, to a virus, would have resembled a fully stocked warehouse of building materials. Everything needed to build a virus was there—everything except a blueprint and a builder. Dr. Spiegelman supplied these by adding small amounts of replicase and natural virus RNA. Within an hour, new viruses were being manufactured in the broth. He extracted replicase and RNA from these new viruses, repeated the process and made still more viruses. Though he needed natural replicase and a "template" of natural RNA to start with, his product in all successive stages could properly be called artificial. Since he was working with RNA viruses, his work didn't excite much popular attention. In the human genetic machinery, the main pattern-carrying chemical is DNA, not RNA. Our cells use RNA in a secondary role. If you think of DNA as the master blueprint, locked in the cell nucleus as in a safe, then RNA works like a kind of copying device, carrying pieces of the pattern from the master blueprint to the cell regions where new structures are being built. If Professor Spiegelman had worked with DNA instead of with the secondary chemical, he might have become a scientific hero.

Biochemists Arthur Kornberg and Mehran Goulian of Stanford University and biophysicist Robert Sinsheimer have made and tested artificial copies of another kind of virus—one whose genetic material is DNA. They started with a template of natural DNA, using techniques similar to Spiegelman's. From then on, they were able to make successive generations of artificial viruses at will. The new viruses were "biologically active"—that is, they had the power to infect living cells and reproduce exactly as natural viruses do. The man-made viruses, in fact, were indistinguishable from natural ones. For the first time, man had made active DNA in a test tube. "If you want to call a virus a living thing," says Professor Charles Price in Pennsylvania, "then you can accurately say that man has now made a living thing."

The next step is to make living things that aren't exact copies of nature's designs. This will be done, presumably, by doctoring the template DNA before it's put into the laboratory broth. Eventually, it may be possible to design whole new creatures—or redesign parts of the human anatomy—by making synthetic DNA with deliberately engineered characteristics. This step has already been started by, among others, Dr. Khorana in Wisconsin.

It may be possible, some scientists think, to design a life-span-lengthening virus. Each species on earth has its characteristic span: A man is allotted some 70 years; a dog, up to 18; a sea turtle, 150. Yet nobody knows precisely why this should be. By continual replication of DNA molecules, life itself has existed on earth for some two billion years; and there seems to be no built-in reason why each individual creature should not live almost eternally through continual regeneration of its own cells. A DNA molecule doesn't "wear out" in the sense that a machine does. Why, then, do a man's cells regenerate less and less perfectly as he passes his 40th year? One possibility, suggests Professor Markert at Yale, is that replicaselike enzymes collect in the cells and interfere with the processing of genetic instructions. Another possibility is that the system for switching genes on and off breaks down—perhaps founders in its own complexity as too many switchings pile up. In either case, it's conceivable that a viral or direct chemical treatment can be devised for nullifying the effects of such cellular garbage.

Another possible cause of aging, some biophysicists think, is cosmic radiation. We're bombarded constantly by high-energy atomic particles from space. We don't feel them, but our DNA might. Each time such a particle hits a DNA molecule, part of the molecule may be chipped off or knocked awry. After 75 years of living, the molecules in all our cells may have sustained so many such "aging hits" that they can't function properly anymore.

"If this is the case," says Dr. Heller, "it's conceivable we may be able to establish a kind of 'youth bank.' At the age of, say, 25, you'd report to the bank and have a patch of skin or a few other cells removed. We should be able, in time, to culture these cells and obtain a significant amount of 25-year-old DNA, and we should also learn how to get DNA back into your living cells. Your 'young' DNA would be stored and protected at, say, the temperature of liquid helium. Every few years, you'd report back to the bank and have your aging DNA diluted with young material. This could retard aging for a long time—perhaps forever."

A similar vision of the future is held by James Bonner, a molecular biologist at the California Institute of Technology. He is interested in the avenue of research being explored by Professor Markert—the mysterious switching on and switching off of genes in various cells. When the mystery is solved, he says, it may be feasible to grow new organs inside the body as replacements for damaged, diseased or aging ones. If you have heart disease, for instance, your body might be induced to grow a new heart next to the old one.

The genetic instructions for growing a heart were in your original cell at conception. As you developed into a small blob of protoplasm, the heart-growing instructions were switched on in some cell or group of cells inside the blob. Now that your heart is fully built and working, the instructions aren't needed and have been switched off. But the instructions, the blueprints, are still there, in your DNA. Can they be switched on again if you need a new heart? Men such as Markert and Bonner are now tracking down the answer.

Stanford University geneticist Joshua Lederberg is interested in the idea of clonal reproduction, as is now practiced with plants and frog embryos. Suppose there were a man such as Albert Einstein, a genetic accident of superior quality. It might be possible to create several thousand exact copies of such a man. A patch of his skin might be removed—100 cells, 1000. Each cell contains a precise duplicate of the DNA that was in his original single cell at conception; and, hence, each contains all the instructions needed to build a whole new Einstein. All the genes except those for making skin are switched off, but possibly a method will be discovered for switching them all back on. Then each cell will have all the relevant properties of a fertilized egg; and from each, in a carefully designed nutrient bath, a complete human being can be grown. The 1000 clones thus made would look and presumably think almost alike.

Procedures such as this will obviously give rise to thorny moral, social and religious problems. If the human life span is greatly lengthened, for example, it may be necessary to curtail new births sharply. If human cloning becomes possible, society will face the problem of deciding who may and may not reproduce himself. Many groups will undoubtedly object that any such tampering with natural processes is wrong on religious grounds. The Second Genesis will not come easily and may, in fact, be acutely painful.

"We're not yet at the point where we dare tamper directly with human genetics," says Dr. Heller, "and some scientists think it's useless right now to begin worrying about the potential problems involved. I strongly disagree. I don't think you should wait for a problem to clobber you before you begin worrying about it."

Many scientists share this view. "Back in 1910," says Dr. Saltman in California, "Einstein enunciated the relationship between energy and matter. Nobody marched in a picket line protesting or agreeing. Yet people should have been thinking about what protest signs they were to carry in 1945 when a mushroom cloud rose over Hiroshima. This time, I say let's show more foresight."

Other scientists are more worried yet. There is a small but vociferous group of men who fear that the world's enthusiasm over nucleic acids will run away with its good sense and that some premature and disastrous attempt may be made quite soon to tinker with humans. The leading spokesman of this group is Professor Barry Commoner, chairman of the botany department at Washington University. Professor Commoner is not convinced that DNA is the sole master chemical of heredity. He thinks that the genetic process may be much more complicated than is now supposed—that other chemicals may play a key role in genetics and may even partly control the molecular make-up of DNA itself. He points to the baffling ambiguities in the DNA amino-acid code, for example. "What worries me," he says, "is the almost religious acceptance of the dogma that DNA is the key to life. There aren't enough questioners around. This sort of blind faith, given its present impetus, could soon thrust us into futile and catastrophically dangerous attempts to alter human life. We'll be tinkering with a delicate mechanism when we don't know enough about it."

Professor Commoner is worried primarily about the scientific or medical consequences of a premature tinkering attempt. He foresees a possible situation in which scientists will believe they know enough about DNA to change its code in some specific way and produce a supposedly desirable new gene. The gene may not work as predicted and the result will be a human monster or a death. "Or the consequences would be more subtle," says Dr. Saltman. "Within the genetic machinery may be connections between one feature and another that we don't even suspect and, in trying to improve one feature, we may unknowingly do damage to another. For example, it would seem desirable to cure sickle-cell anemia, a hereditary disease that's apparently caused by a single misprint in the DNA code. But it turns out that, in the Mediterranean countries and Africa, people who have the disease are highly resistant to malaria. This is the kind of problem we may blunder into when we start tinkering."

But Dr. Saltman and others are also concerned about the moral implications of genetic tinkering. The most notorious recent attempt to influence human genetics occurred in Nazi Germany two and a half decades ago. The Nazis planned to breed an Aryan master race by direct governmental interference in the people's choice of mates. Jews were categorically excluded from the planned genetic pool and, to a lesser extent, so were Italians, Spaniards and other dark-skinned peoples. The idealized prototype was the blue eyed, fair-skinned blond, and young men and women carrying these preferred genes were encouraged to procreate, with or without marriage. The plan was in full force for only six or seven years, not long enough to produce scientifically viable results; but it illustrated some of the worst moral, if not medical, dangers in herent in human genetic engineering.

"It showed," says Dr. Saltman, "that the question 'What are good genes?' is hard to answer. Who is to answer it? If the privilege is granted to me, I'll say my genes are the best and thereby, perhaps, exclude yours. In a free society, we assume that nobody has a right to pass laws about anybody else's genes."

Free-choice mating has served humanity well, though slowly. The breed has improved through natural selection, raising us from animal status to kings of the earth in perhaps 1,000,000 years. Genes producing such anomalies as Mongolism tend to get bred out of the genetic pool as soon as they appear, since people carrying these genes don't often find mates. "This is how things have been for millennia," says Professor Commoner. "Now along comes the discovery of DNA and, with it, a dream that could turn into a nightmare. A dream of hurrying up evolution—a dream of a quick fix."

The Nazi dream was a slow fix, since it would have taken many generations to breed the proposed master race through legislated mating. Other slow fixes have also been proposed from time to time and each has had its problems. The renowned American geneticist Hermann Joseph Muller, who died in 1967, spent much of his life trying to get people interested in a "eugenics bank" of frozen sperm taken from men having what Muller considered desirable qualities: cooperativeness, physical vigor, intelligence, empathy. Muller's proposal was to round up married women of similar qualities, have them inseminated from his eugenics bank and thus engineer a superior breed. The plan sounded just barely plausible on paper, but there was a practical problem: To most women and their husbands, nature's untidy method of procreation is more fun and more rewarding to the husband's ego.

Another slow fix has been proposed by Crick. The codiscoverer of the DNA structure starts with the premise that people with supposedly desirable qualities, such as intelligence and vigor, tend to rise to the top of the heap economically. Thus, says Crick, it might be possible to engineer a system of eugenics-by-economics under which it would be easier for the rich than for the poor to procreate. This could be done by taxing children. Commenting on this proposal, Dr. Commoner dryly remarks: "A man's cultural bias is inextricably interwoven with his views of what is and what isn't desirable in a human."

The nucleic acids, with their promise of a quick fix, make such moral and social problems even more acute. "I wonder about all kinds of odd things," says Dr. Heller. "Suppose we learn how to breed Homo superior instantly—not by slow changes over generations but maybe in a few years' series of treatments such as the polio shots of the late 1950s. Suppose we can even agree on what are and what aren't desirable genes. When Homo superior begins to strut about the earth, how will we poor old remnants of Homo sapiens feel? Will we be forced into ghettos? I want people to start worrying about this kind of problem now. while there's still time to think calmly and before irrevocable steps have been taken."

Now may already be a little too late. Some scientists believe the Second Genesis will rush at us quickly, as atomic energy did, instead of arriving in slow stages and giving us time to sort out our thoughts. Writing in the Bulletin of the Atomic Scientists last year, geneticist Lederberg discussed such possibilities as human cloning in matter-of-fact tones, obviously expecting little argument from his learned readers. "If I differ from the consensus of my colleagues," he said, "it may be only in suggesting a time scale of a few years rather than decades."