Brave New Worlds Staying Human in the Genetic Future

Brave New Worlds Staying Human in the Genetic Future
CHAPTER ONE
Brave New Worlds
Staying Human in the Genetic Future

By BRYAN APPLEYARD
Viking
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The Future

Biology is likely to dominate science for the next century.
--KAY DAVIES, professor of genetics, University of Oxford



Any forecast of the future must make one of two assumptions: Either we manage this deeper genetic knowledge wisely or we do not. In the first case we can be reasonably optimistic. In the second case there need be no limit to our pessimism.

Forecasting the future is dangerous. Sometimes we expect too little to happen. At the end of the nineteenth century, some physicists believed their subject was almost complete. This was just before Planck's quantum theory and Einstein's relativity theory started a revolution in physics that was to dominate the next fifty years of science, posing fundamental problems that remain unresolved.

Or we expect too much. According to the 1968 film 2001: A Space Odyssey, we should by now have self-conscious computers and be ready to send astronauts to Jupiter. In fact, since the moon landings in the 1960s, humans have not even left Earth's orbit and artificial intelligence research has been stalled for twenty years.

The difficulty is that any forecast assumes that present developments will continue on a straight line into the future. As a result, we make naive assumptions. But how else are we to proceed? It is, by definition, impossible to forecast the unforeseen. We have only the present as evidence, so the futures we construct are always destined to be commentaries on the present. The reality is that problems and breakthroughs, not straight lines, are the main determinants of progress. The cost and dubious benefits of space travel have stopped us going to Jupiter or even returning to the moon, while quantum theory has produced an information revolution. Neither the problem nor the breakthrough could have been anticipated.

Forecasting the future of genetics is a riskier endeavor than most. At one level, the future looks very predictable indeed: The overall pattern of developments in molecular biology seems clear and we can, therefore, expect more of the same. Most geneticists seem to know exactly where they are going. Yet at another level, it seems impossible to predict anything. Our present genetic knowledge is notably lacking in direct, practical applications. We may be able to continue increasing our knowledge of what genes do, but we do not know what to do with that information, or, indeed, whether we can do anything. Some say molecular biology is still waiting for its Newton or Einstein, its big theorist. In this view, the unforeseen element is the overarching theory that makes sense of it.

One final and, for geneticists, depressing possibility is that genetics has distorted the entire discipline of biology. Maybe we have taken DNA too seriously. Perhaps proteins are, in reality, the most decisive substances in the biochemical system. They, not DNA or its precursor replicating molecules, may have been the start of the life process. By concentrating so much on the gene, we may have ignored the dynamics of the whole organism, and once we escape from this delusion, genetics will decline in importance, becoming one aspect of biology.

Whichever future we choose, we are likely to be wrong. Yet the present implications of developments in genetics are too vast to be ignored. The future presses in on us daily. News stories demand that we ask ourselves, What if? Dolly the sheep stunned both the scientific and the lay world in 1997: Cloning from adult cells was now possible. Suddenly the future seemed to have arrived. But not quite, for such stories are all about developments as yet unapplied in the human realm, and they can only be understood from the perspective of a possible future.

Scientists tend to be reticent about addressing this. They dislike sensational stories about the possibility of "designer babies" or "brave new worlds" of cloned human beings. They say either that we are a long way from being able to do anything like that, or that there is no reason to do it, so it will not be done. But Dolly undermined the credibility of the first position. (The day before she was revealed to the world, it would have been easy to find a large number of geneticists who would have insisted that cloning from adult cells was either impossible or a long way in the future. All of them would have been wrong.) And the widespread insistence that there could be no reason to clone human beings simply betrays an innocence about the infinite demands of human vanity. This is the age of consumption--if it can be bought, it will be.

So we must look forward. Perhaps the most low-risk forecast concerns the Human Genome Project--the reading of all the chemical information stored in human DNA. Early in the next century, "Adam II" will have been created. We will have a complete list of the three billion chemical letters that compose the message of the human genome.

From that point onward forecasting becomes much more risky because we do not know how we will be able to apply that information or, indeed, how much of it we shall understand. It could be many years before we can interpret all the messages buried in the genome. And it may take decades or centuries to work out the complete biochemistry of the body. At that point we shall be able to say that the study of anatomy is complete--that we shall know the entire system of the human body. Perhaps, some have suggested, this stage will be reached around the year 2100.

It is generally assumed that both before and after the completion of the Human Genome Project, applications will flow continuously from the information it provides. These applications will be primarily about the improvement of the physical human condition. Medically, this is an urgent matter because we seem to have almost reached the limit of improvement using conventional methods. Doctors hope genetics will lead them away from a road that is looking increasingly like a dead end.

For example, life expectancy has almost doubled in the developed world over the last hundred years, creating hopes among many that this rate of improvement will continue (straight-line thinking again). But, in fact, for those reaching the age of sixty, life expectancy is only a few months more than it was at the beginning of the century. This suggests that our main achievement has been to stop people from dying young rather than to make them live longer. We have failed, so far, to do anything about aging other than to allow more people to experience it.

Genetics has provided many speculative possibilities for extending the human life span by slowing, or compensating for, the changes that take place at the molecular level. Aging may be, after all, an entirely genetic process caused by a buildup of mutations in the DNA of the somatic cells. Or, even if aging is not directly genetic, it may involve cellular processes that can be genetically regulated.

The difficulty is that any attempt to intervene entails the thwarting of nature at a very fundamental level. From the point of view of the gene, our longevity is neither here nor there. Once we have finished reproducing, it is immaterial to our genes whether we live or die; we have done our job of transmitting them to the next generation. Yet even so, there is biological evidence that death does not have to happen. Stem cells in the bone marrow and cancer cells are immortal; they are capable of reproducing themselves forever. So, at the cellular level, death is not an inevitable outcome for biological systems. If we can discover what keeps those cells going, then perhaps we can treat all other cells to behave in the same way. Immortality is no longer completely unthinkable.

Currently, eighty-five might be said to be the optimum human age--the life span which a reasonably healthy, and lucky, person might expect. The utopian vision of current Western medicine is that of a person who drops painlessly dead on the golf course at eighty-five after a disease-free life. However, some now talk of using genetics to increase that optimum age to one hundred twenty-five. Yet even if these scientists were successful, the problems, both for the individual and society, would be enormous. For example: How much of this increased life span would be spent in helpless dependency?

Oddly enough, the conquest of individual diseases does not have much effect on the statistics of longevity. Almost all the increase in life span in this century has been due to public health measures and improved nutrition. Even curing cancer would add only a year or two to the average Western life. Yet, clearly, it is better not to be ill, and, to the individual with cancer, statistics provide little consolation. So it is the treatment of illness that is the primary driving force of genetics.

The immediate future of medical genetics looks reasonably clear. The 4,000 genes involved in single-gene disorders will be progressively identified, and scientists will attempt to identify the genes involved in polygenic illnesses--those arising from the interaction of a number of genes. This is a much more complex process, but it will bring genetics into many more lives since single-gene disorders are rare, while polygenic disorders are common.

A single-gene disorder like Huntington's disease or muscular dystrophy tends to be a simple, all-or-nothing event: If you have the single dominant gene for Huntington's or the two recessive genes for muscular dystrophy, you will get the disease. Some environmental (not directly genetic) factors may determine the time and rate of onset, but these do not alter the fact that the conditions are genetically predestined. This makes tracking the genes with the current state of knowledge and technology relatively simple--they follow clear Mendelian patterns of inheritance with no significant ambiguity about the role of the genes as opposed to the environment. Here is a bad gene and it causes this disease.

There remains, however, the ambiguity about the evolutionary significance of these aberrant genes. Tampering even with these apparently clear-cut cases of disease genes may not be a simple matter. Genes that do one thing may have other, entirely unrelated effects--a phenomenon known as pleiotropy. Genes that appear to be bad may provide benefits of which we know nothing. A single sickle-cell anemia gene, for example, provides some protection against malaria. To describe a gene as "bad," therefore, is risky--it may be "good" in ways we cannot yet imagine. But, leaving that ambiguity aside, the origins and broad causal pathways of many single-gene disorders are now understood, even though little or nothing of therapeutic value can yet be done with that understanding.

Multigene disorders, however, are much more complex. Even if just two genes are involved, the difficulty of tracking them increases enormously. There are three billion chemical bases and maybe 100,000 genes, all of different shapes and sizes, in the human genome. As many as 20 genes may be involved in some disorders. Even if we were to successfully track these genes, the picture would be far more ambiguous than that of the single-gene disease. Say we were able to identify a number of genes linked to a form of heart disease. This would tell us something about the health prospects of anybody possessing that combination of genes, but it would not be the sort of dear-cut information we get when we identify single-gene disorders. It would say simply that this person is at risk from or predisposed to heart disease, not that he will definitely get it. If that person works out and doesn't drink, smoke, or eat too much fat, then he can reduce that risk and may become ill and die as a result of something entirely unrelated to heart disease. Or he may not.

Almost all polygenic disorders are likely to involve some degree of interaction with the environment. In the case of the man at risk from heart disease, "environment" refers to his fitness, eating, drinking, and smoking habits. Even if this environment is corrected to take account of the increased risk, the man's heart disease genes may interact with other genes and lead to a heart attack anyway, no matter what his general state of health.

The environment encompasses not only psychological and physiological factors, but also those more conventionally seen as "environmental": air quality, pollution, heat, cold, sunlight, and so on. The impact of some of these elements have been isolated--for example, tobacco and sunshine are factors in lung and skin cancers respectively--but many have not. In fact, it is probably misleading to think of the environment in which we live as simply benign or harmful. Of course, some elements of that environment, such as clean air, may be benign, and some, like tobacco smoke, may be harmful. But the picture that is now emerging is that life is a constant interaction with the external world at the molecular level. All life for as long as it manages to endure is an incredibly ingenious victory against huge environmental armies.

Disentangling the incidents in this war will be difficult and our conclusions may frequently be illusory. So the next wave of medical information arising from genetics is not going to be nearly as clear as the first wave. Medical knowledge will move into the realm of probabilities. For example, say that in ten years' time, a doctor takes a DNA sample from a fetus. He then sequences the DNA, using faster technology than anything we now have, and seeks out whatever single-gene or polygenic disorders have been identified by that time. He finds that the fetus has a combination of genes that makes it more prone to heart disease than the average person. The doctor will be able to quantify the risk. But the figures will not be simple: He may say, for example, that, given a normal lifestyle, this person will have a 46 percent chance of having a heart attack by the age of thirty. Given an unusually healthy lifestyle, the risk may fall to, say, 39 percent by the age of forty.

These figures will be based on large population studies which tell the doctor that, say, out of every hundred people with these genes who maintain a healthy lifestyle, 39 had heart attacks by the age of forty. This may sound like solid information--and for medical policymakers, insurance companies, or hospitals, it is, since they look at large numbers of people, whereas we only look at a few, generally ourselves and our families. But what are the parents to make of these figures? Does it mean their baby is ill? When it is born it will almost certainly look and behave like any other baby. Yet there is this strange phantom of probabilities, of calculable futures, already present at its birth. We have always known that our newborn babies will one day die, but soon we will be told when and why it is likely to happen.

This involves the whole relationship of the individual to a statistically described world, and it calls into question our concept of disease. It will demand more of patients and doctors and, most importantly, more of their relationships.

The potential for refinement of such predictive thinking is huge. Any illness that can be shown to have a genetic component--and that, some argue, means every illness--may be detectable as a probability or predisposition from a sample of our DNA. Vast probability charts--scientific horoscopes--of our susceptibilities may be constructed and whole lifestyles designed to minimize risk: This person should not smoke and that person should avoid red meat or taking a job in a particular kind of factory. In the future we may be given, at birth, a lifelong program precisely tuned to our own genetic predispositions.

This need not mean we will be enslaved by statistics. It may in fact mean we will be liberated. For example, current medical advice for the prevention of heart disease includes cutting down on animal fats, exercising, and avoiding smoking. But in reality, doctors know perfectly well this advice is based on ignorance; they simply do not know whether any particular person needs to do those things, only that, in general, people do. If we knew which people's arteries were likely to become clogged as a result of the consumption of animal fats, then we could just tell them to cut down their intake. The rest of us could eat as much as we liked, and possibly some people could even smoke as much as they liked. In this sense genetics could free people from a whole range of anxieties that doctors feel obliged to impose on the whole population on the basis that they may improve the health of a few. Our health profiles would become much more precise and personal. In theory, the whole health-care business could become much more efficient.

And it may not simply be familiar physical illnesses that are drawn into this realm of probabilities and predictions. Most serious mental illnesses are now thought to have genetic components. Manic depression and schizophrenia are assumed to be overwhelmingly genetically determined, and a worldwide search is in progress for the genes involved. Other, less serious mental disturbances may also be genetically diagnosed.

At this point the question of what is and is not an illness arises. Schizophrenia is obviously a debilitating disorder, as is manic depression. But what about simple depression? Currently, how we view a particular state of depression may result in hospitalization, psychotherapy, a consoling chat, the prescription of antidepressants, or a brisk insistence that life is tough, pull yourself together, and get on with it. The dividing lines between the levels of seriousness will be vague. But genetics may offer more precise divisions. As one researcher put it to me: "[Genetics] provides an objective basis for a subjective diagnosis." We may be able to say that this depression has a recognizable genetic component and that one does not.

So, in looking to the future, the question becomes: How much of human life will be explicable in terms of genetics? In the current climate the usual answer is: Almost every aspect of human life has a large and frequently decisive genetic component.

The psychologist Thomas Bouchard has said, "For almost every behavioral trait so far investigated, from reaction time to religiosity, an important fraction of the variation among people turns out to be associated with genetic variation. This fact need no longer be subject to debate; rather it is time instead to consider its implications." This is the mainstream, working assumption in science today. On that assumption, schizophrenia, as well as other forms of behavior we would not necessarily consider as evidence of disease, could be explained by genetics. Routine depression, a tendency to lose one's temper, sexual promiscuity, or anything even slightly out of the ordinary could be shown to have genetic roots. In itself this is not surprising; we often notice that children inherit not just the looks but the attitudes of one or both of their parents. What will be new in the future will be, first, exact knowledge of the precise genes involved and, second, the possibility of doing something about such tendencies.

Of course, we might now say, But you are not sick if you tend to get angry. But what sickness is or is not tends to be defined by the prevailing wisdom. Just as genetics may come to teach us that somebody with a predisposition to heart disease later in life is sick now, so it may come to convince us that certain personality traits are sicknesses and should be treated as such. Look at the way surgery is now widely used for cosmetic purposes. Yet do we regard ugliness as a sickness? Many people, both doctors and patients alike, now act as though it is. The possibility of changing any human condition immediately transfers that condition into the medical realm--a place dominated by the simple polarity of sickness versus health.

This makes it highly unlikely that genetics will reduce overall medical costs, though many have hoped that this would happen because of the resulting increased effectiveness of preventive medicine. But if genetics also increases the number of human attributes classified as illnesses--or simply as treatable disadvantages--then medical spending will continue to rise. It will also tend to be even more concentrated on the richest sectors of society--those most able to afford the diagnostic and therapeutic programs involved.

But there is another form of "preventive medicine"--abortion. Knowing the gene for a particular disease may not yet lead to any treatment, but it does, if the gene is identified prenatally, offer the choice of abortion. Abortion is the one medical intervention based on medical genetics which is already widely available. Prenatal tests are offered to women thought to be at risk of having genetically abnormal babies. These tests--such as amniocentesis or chorionic villus sampling--are invasive and slightly risky, so they are not offered to every mother-to-be. If they are positive, abortion is frequently the only response available.

But if genetic flaws can be identified even earlier, abortion can sometimes be avoided for at-risk families. The use of preimplantation diagnosis, pioneered at the Hammersmith Hospital in London for families at risk of cystic fibrosis, involves taking eggs from the mother, fertilizing them in vitro with the husband's sperm, and incubating them for three days, still outside the body, until they form a cluster of eight cells. One cell is then removed from each embryo and tested for the disease gene (rather amazingly this removal of one eighth of the mass of the embryo has no effect on its future development). If the disease gene is present, the embryo is discarded. A healthy embryo is then reimplanted into the mother.

More rapid DNA sequencing techniques and greater knowledge about the effects of specific genes would mean that a much larger range of conditions could be sought in the embryonic cell. These conditions need not be what we would now classify as serious diseases. In time they could, for example, forecast anything from the eye color to the likely intelligence or sexual orientation of the child. Preimplantation diagnosis could offer, to those who could afford it, a choice of what kind of child they would like.

But prenatal testing on a larger scale will only happen when a cheaper, easier method is found of getting at embryonic or fetal cells. The best hope is the use of a simple blood sample taken from the mother. Fetal cells do circulate in the mother's blood and could, therefore, be isolated and tested. This would mean that all pregnant women could be routinely tested and, subsequently, offered a vast amount of information about their babies. However, much of this information would be in the form of statistical probabilities. Confronted with this kind of information, people will seek explanations. Thus, one absolute certainty for the future is that genetic counseling is bound to be a massively expanding industry.

Also in the near future a number of specific medical treatments are likely to become available. The overwhelming consensus among geneticists is that the development of highly specific though conventional treatments will be the first effective fruits of the Human Genome Project. Because genetics will tell us a lot more about individuals and their biochemical constitutions, we will be able to target particular conditions more exactly. In this form, genetics can be seen as no more than an extension of existing medicine. We simply will know a great deal more about the way the body works and we will be able to provide treatments that look much the same as existing treatments (pills, injections) but that act more precisely not only on a specific disease but also on the specific individual. This process will be rapidly advanced by the genetic engineering of animals so that, from the point of view of the disease, they become more like humans.

"Mice don't get Alzheimer's," explained one man involved in this industry, "[and] they don't get high cholesterol. But we can genetically engineer these conditions into an animal so you have a whole animal system other than a human being on which to measure and evaluate drugs. This tool, before we had genetically engineered animals, was unavailable. It will accelerate the drug development process. Think how valuable that tool can be to any drug-testing or drug-development company."

Such treatments will also result in a massive expansion of the existing industry of protein production via genetic engineering. Currently this production of protein happens through either engineered bacteria or animals--typically goats and sheep--that have been genetically altered to express a human protein in their milk. Assuming this technology continues to be the most effective method, we can expect the development of huge new protein factories and farms, the latter probably relying on techniques developed once the mysteries of the cloning of Dolly have been deciphered.

Animals, usually pigs, will also be more radically engineered to produce organs suitable for transplantations to humans--so-called xenotransplantation. This was first tried, absurdly prematurely, in 1964 in Jackson, Mississippi, when a baboon heart was transplanted to a human who, of course, died. Now the procedure is technologically possible but fraught with uncertainties about the precise tuning of the immune response and the possibility of transferring animal viruses to humans. This is exactly what appears to have happened in the case of acquired immune deficiency syndrome (AIDS), a disease which is thought to have found its way into humans from monkeys. The science of immunity seems certain to benefit from the knowledge derived from the genome project. A reasonable straight-line forecast would be that xenotransplantation will happen quite soon and will become commonplace over the next couple of decades.

Distinctively human body parts also may be produced if we succeed in mastering the control mechanisms of the genes. Again, Dolly seems to point the way by suggesting that the genes in differentiated cells may be controllable. For example, we might begin with one cell from a patient and, by switching on the right genes in the right order and in the right environment, grow a new arm or leg. In this case there would be fewer or no problems with rejection by the immune system because the new limb would be genetically identical to the rest of the patient's body.

Finally, knowledge of gene regulation may also lead to a breakthrough in the treatment of cancer--the disease which kills one in three of us. All cancer is genetic because it involves an alteration in a cell's DNA. Some types are also genetic in the sense that they are hereditary, but the remainder seem to be the result of mutations due to environmental factors or the action of viruses which replicate by changing the DNA of the host cells. If we can regulate genes with sufficient accuracy, we can, in theory at least, turn off cancer-causing genes or otherwise change the genetics of cancer cells to eliminate tumors.

Already we have isolated a number of genetic factors involved in cancers. The first breakthrough came as long ago as the 1960s when the American scientist Peyton Rous discovered a gene--christened "sarc"--that caused cancer in chickens. Since then, there have been steady though not spectacular developments. Colon cancer and breast cancer, the most common form of the disease in women, have been traced to certain genes, called oncogenes. There will be a huge increase in the number of cancer-causing genes we are able to identify.

Genetic advances have already transformed the way cancer is regarded. Traditionally cancers have been categorized on the basis of the part of the body in which they occur--colon cancer, lung cancer, and so on. It is now becoming clear that it is more accurate to categorize cancers on the basis of the chemical pathways involved. So a cancer of the throat may, biochemically, have more in common with a cancer of the bowel than it does with another throat cancer. As the geneticist Eric Lander said: "We will classify the tumor according to the pathway, not the site in the body."

One form of specific human cloning is currently being used as a treatment for cancer. This involves the production of so-called monoclonal antibodies. White blood cells are removed from a patient and exposed to cancer cells in the hope that they will produce the correct antibodies to destroy the cancer. Only about one in 100,000 white cells will react in this way. But this is enough if they can then be cloned and injected back into the patient to seek out and destroy tumors. This technique has long been promising, but results are so far inconclusive.

These are simply examples of the use of genetics against cancer. The field of cancer research is so vast that there are many others. Current cancer treatment is still largely based on the conventional methods of chemotherapy, radiation, and surgery. In spite of all the effort in the past half century, cancer treatment has only been refined, not revolutionized. While would-be revolutionaries now look to genetics, in view of the history, it would be safest to say only that some kind of breakthrough may happen in the next ten years.

Gene therapy, for the moment, remains a more distant prospect. "The theory of gene therapy is impeccable," one geneticist told me. Unfortunately, the practice is not. There is a gap between what happens in the test tube and what happens in patients. It has been suggested that it will be at least fifty years before gene therapy becomes a widespread medical practice. The difficulties of targeting genes and changing enough cells to have any effect have, so far, proved insuperable. "Gene delivery," as Michael Blaese at the National Institutes of Health in Bethesda put it, "is the issue."

The recent development of an artificial human chromosome suggests one way of delivering genes. In 1983, a yeast artificial chromosome (YAC) was created. YACs can now be made to order and are used to store millions of DNA base pairs. They have been described as the "beasts of burden" for the Human Genome Project. After that the race was on to make what was conveniently called the Big Mammalian Artificial Chromosome--the Big Mac. This has finally resulted in the creation of an artificial human chromosome.

The point about artificial chromosomes is that they may offer a way of carrying exactly the genes and regulatory sequences we need into any organism, so that transgenic animals--creatures which carry human genes--can be more efficiently created than they are at the moment. The genes would simply be ferried into their cells using the artificial chromosome.

Similarly, gene therapy could be made to work. In both cases new genes would be permanently added and would not disturb the work of existing genes. One danger, unfortunately, of existing gene therapy techniques is that, in inserting genes into the targeted place, we can end up inserting them in the wrong place and distorting healthy sequences.

Germ line therapy--in which the sex cells are altered so that future generations are treated by current medical interventions--is also on the agenda, but here the issues are more complex. It may seem obvious that if someday we are able to change the DNA in sex cells so that future generations will be immune to AIDS, then we should do so. As yet there is no prospect of that happening, but even if there were, could we ever be sure that we were not creating new problems for the future? If, for example, we could eliminate sickle-cell anemia through germ line therapy, would that result in an increase in malaria? Tinkering with the whole human gene pool may have consequences we cannot possibly foresee. Will we have so much confidence in our knowledge that we feel able to alter the outcome of millions of years of evolution?

The foregoing examples are only a sampling of possible future developments in medical genetics. Many others will be announced month by month, including some that will come as a complete shock, even to geneticists. The general picture, however, is clear: We are at a stage in our understanding of human genetics where much is promised but little of direct, practical value has been achieved. In fact, the word "much" is probably too weak. It is more true to say that almost everything is promised--from immortality to a cure for cancer to a new consumer market in offspring characteristics. Developments in genetics offer the possibility of bringing all our life processes under control.

Anything, it is now clear, may be possible. And that includes penetrating the human mind. Molecular biology in general and genetics in particular offer new ways of understanding the mind. Evolutionary psychology is now an active and fashionable area of research, based on the idea that our psychological condition can be investigated by viewing the mind as a product of evolution rather than as a blank sheet written over by culture and environment. We can now study human sexual behavior in the same way we might study that of chimpanzees--as a series of strategies that have been tried and tested by the evolutionary process and passed on by heredity. The central biological insight that we are connected to all other living things is being extended to the way we act and think. Psychology, psychiatry, sociology, and even politics can be viewed and analyzed as the products of evolution. In the future it is quite possible--indeed, to some extent it is already happening--that psychoanalysts will refer to Darwin rather than Freud when attempting to understand mental disorder. It is likely that, in time, the study of the mind will become much more like the study of anatomy.

Meanwhile, Francis Crick has forecast the explosive growth of "molecular psychology"--the study of the workings of the brain at the molecular level. "The present state of the brain sciences," he has written, "reminds me of the state of molecular biology and embryology in, say, the 1920s and 1930s. Many interesting things have been discovered, each year steady progress is being made on many fronts, but the major questions are still largely unanswered and are unlikely to be without new technologies and new ideas."

Molecular psychology could link up with evolutionary psychology and with research into genetic predisposition to mental disturbance to form a new science of the mind based entirely in biology. "We will have," as one researcher put it, "a much clearer understanding of what personality means biochemically."

But, in the future, genetics may also affect much more than just the individual human life. For a start, the medical developments I have noted have wider policy implications. Accurate prenatal or even postnatal diagnosis of future conditions may lead to a nightmare for insurance companies and for their customers. In countries like the United States, where the health care system is largely financed by private insurance companies rather than the government, as in Britain, a conflict exists between the commercial interests of the companies and the public interest in providing health care. If DNA tests for a wide range of diseases are demanded by insurance companies, then, inevitably, a large number of people are going to find themselves uninsurable or with cripplingly high premiums.

All the geneticists I have met have said--perhaps because of their political inclinations--that genetics will destroy the present American health care system. They say it will have to be replaced with some kind of national health service like Britain's. Whether this is true or not, it is clear that developments in genetics will force huge changes in the way health coverage is provided. The full implications of these changes are only just beginning to be felt.

Advances in genetics also have other, even darker, policy implications. First, they suggest that human characteristics are, to a greater or lesser extent, fixed at birth, that people are made by nature (their biology) rather than by nurture (their environment). Second, they provide information not just about individuals, but also about groups of people. For example, we may well be able to identify a whole range of precise differences between races, as well as genetic dispositions to criminality, dissidence, or any other traits perceived as socially undesirable. The readout of your genome at birth may not just tell your doctor how likely you are to have a heart attack; it may also tell him how likely you are to rob a bank or blow up a federal building. Genetic information may be able to create clearly definable--and very easily identifiable--criminal or politically dissident classes.

These are scientific developments which can only really be understood in moral, philosophical, and political terms. The improvements in the physical human condition that may flow from developments in genetics will be trivial compared to the catastrophe that will befall us if we mishandle the information in the wider public realm. Concealed within the knowledge we are now acquiring are insights that may be profoundly socially divisive and which could overthrow the basis on which the wealth and stability of Western democracies are constructed. Any forecast of the future must make one of two assumptions: Either we manage this deeper genetic knowledge wisely or we do not. In the first case we can be reasonably optimistic. In the second case there need be no limit to our pessimism.

Outside the human realm, advances have already resulted in direct, practical applications. The primary theme of developments in the genetics of animals and plants is the breaking down of barriers between species. Transgenic animals are now relatively commonplace, as are transgenic plants. These "chimeras" can be created because of our power--derived from the recombinant DNA technology developed in the early 1970s--to move DNA from one species to another. I have already mentioned the use of transgenics in medicine. In agriculture, transporting genes across species results in the enhancement or preservation of favored characteristics far more rapidly and efficiently than traditional breeding methods. Crops can be made resistant to disease or able to endure a much higher level of chemical treatment to eradicate destructive pests. Or they can be made to produce fruit with more convenient characteristics, like the now famous tomato that lasts longer on supermarket shelves (thanks to a gene christened the Flavor Saver Gene by Calgene, the company involved). Dozens of species have already been transformed, and, within a few years, techniques will become available for the genetic manipulation of all major crops species.

These advances could go much further than merely producing better versions of the same species; they could lead to wholly new species. The writer Colin Tudge speculates, for example, about the possibility. of a Virginia creeper that does not respond to the seasons and is tolerant of cold, providing insulation for houses over the winter and producing strawberries. Eventually, Tudge speculates, we can move on to developing life from scratch: "So perhaps in a hundred years, and perhaps less, there will surely be a `life creation project' comparable with the Human Genome Project of today."

The British geneticist Steve Jones takes this even further. In his view, plants could become biological factories, producing anything we want and completely displacing animals: "All this may mean that plants will soon do almost everything and that animals will fade in importance as--perhaps--the salmon-flavoured banana takes over." And he suggests: "The rural landscape may become one in which asexual cows feed on engineered grass under the shade of clonal trees."

And so on and so on. We are in the process of taking control of life. Some aspects of this process will appear to be no different from previous scientific and technological developments. Other aspects, however, will be profoundly different. We will produce new species, diagnose illness long before it happens, "know" human beings at the biochemical level, manipulate our reproductive processes, and change ourselves.

Such developments are like nothing that has gone before. They represent a fundamental redefinition of human capability. The remainder of this book is about what that really--as opposed to merely scientifically--means.