Steve Jones - The Language of the Genes

Both genetical and environmentalist views of blood pressure or IQ are naive. Characters like these are shaped by both gene.ind environment and it is meaningless to ask about genetic differences except in populations that live in the same conditions. I once did a simple experiment with a group of students. 1 divided them on the basis of hair colour. The fair-haired group were sent downstairs for coffee. The other set measured their own resting blood pressure. I then summoned the coffee-drinkers. As they had just run upstairs and were dosed with caffeine, their average score was higher than that of the dark-haired students. There was an association between blood pressure and hair colour.

Family studies show that much of the variation in resting blood pressure is due to inherited variation. To most of the students this proved the existence of a genetic difference in blood-pressure between dark and fair-haired people. Only when let into the simple secret of the differences in the experiences of each group was it obvious what is wrong in that claim. The students had made the same mistake as the educationists. High heritability combined with a difference between groups need not say anything about genes. The race and IQ story is, in the main, one of a dismal failure to understand basic biology.

A belief in heredity, rather like faith in predestination, is a good excuse for doing nothing. At least the environmentalist version can be used to try to improve matters. The genetkal view is often taken as a chance to blame the victim; to excuse injustice because it is determined by nature. In the last chapter of Daniel Deronda, biology wins. The hero returns to his ancestral roots and marries Mirah Mordecai, with the Cohen family in attendance. His admirer Gwendolen Harleth is left to console herself with the memory of her unlikeablc mate Henleigh Grand-court, drowned a few pages earlier. Determinism triumphs, which is convenient for the novelist. Fortunately, real life is more complicated than that. One of the most remarkable discoveries made by the new genetics has been to show how little we understand about the human condition that we did not know before.

If, by chance, you are reading this book on a train, or in a library, or anywhere apart from in solitude, steal a glance at the person to your left and to your right. Then, comfort yourself with the knowledge that two of the three of you will die as a result of errors in (or side-effects of) the genes you carry. Should that idea be unwelcome, it is worth remembering that a century ago, in that train or library (and depending on the age of your companions) two of the three of you would be dead already.

Life, towards the end of the second millennium, underwent a great change. A British baby born today who lives through the difficult first six months has only about one chance in a hundred of failing to make it to adulthood. In Victorian times — and long before — the figure was, for most newborns, about one in two. In those days, death came from outside: from starvation, infection, or cold. The eugenicists were concerned about the inborn weaknesses of future generations, but in fact most of their fellow citizens died for reasons not directly connected with their genes. Now things are different: we have won the battle against the external world and face the enemy within; our innate failings, central as they are to ailments such as heart disease, diabetes or cancer. As a result, most of us nowadays die of a genetic disease (although not many notice). Genes impinge upon us more than they did in Galton's time and our new ability to read their message may alter lives and deaths in unexpected ways.

Both Galton's Laboratory for National Eugenics and Davenport's Eugenics Records Office (which changed its identity through a merger with the Cold Spring Harbor Laboratory) are now world centres for human genetics. They and the hundreds of research groups that descend from them have come up with the technology for searching out genetic imperfection thut (I.ilion and Davenport lacked. Many of the questions ih.it obsessed ilu- biologists of a century ago have been answered. What is the relationship between people and genes now that we may soon have the tools to identify the inadequate and to carry out some kind of eugenical programme if one was called for? Will we screen all babies at birth; or is that a step too far?

No serious scientist has any interest in a genetically planned society. But the explosion in genetics means that, like it or not, we must face ethical problems of the kind so comprehensively ignored by its founders. Can, or should, choices be made on the basis of DNA? What is the balance between the rights of individuals and of society in the light of the new biology; and is there any need to worry — as the eugenicists thought — about those of unborn generations? One intellectual hero, Sam Goldwyn, dismissed the issue by asking 'what did posterity ever do for me?', but his predecessor, Plato, saw a moral duty to the future in that 'mankind gains its hope of immortality by having children 7. To interfere with the genes of the present has an effect on that future and to diagnose an error in one individual at once draws in his family; those alive and those yet to be. Where should the duties of science end?

Genetics has undergone a healthy shift in attitude. Most of its practitioners are not concerned with the quality of the distant future. They feel responsible to people rather than to populations; to today and not to tomorrow. Biologists are, indeed, more cautious about their work than is the public. In one poll three out of four Americans found the idea of inserting genes into human sperm or egg quite acceptable but almost no scientist would contemplate the idea.

In the nineteenth century the bacterial theory revolutionized medicine. Some hope that DNA will do the same in the twenty-first. Genetics might help to predict disease before symptoms appear, prevent it before damage is done or even cure it by molecular microsurgery. Whether or not it succeeds, it will reveal many secrets. DNA may have shattered Plato's notion of the perfect human, but reminds us of his notion that men may be classified by their very nature — not just into those of gold, silver, iron and brass; but into thousands of classes, each at risk of certain diseases, of certain environments, and each, perhaps, endowed with some unique and inborn talent. Are we ready to expose the skeletons hidden in every genetical cupboard? Mass screens for genetic defects are in the air (with the British government among the first to offer its population for the task). The eugenicists would have been happy with the idea and libertarians are alarmed; but now it seems that the job may be more difficult than anyone had hoped — or feared.

For much of the time genetics deals with healthy people, either carriers of single copies of recessive genes, or those with damaged DNA that might affect their future health. By so doing, it draws more and more under the aegis of medicine. Genetics was once a science of the exceptions. Dreadful as inherited disease might be for the families involved, it did not seem to impose upon most people. Genes are responsible for severe inborn defects, but most are impossible to treat (so that those affected die young) and each is rare. With an overall incidence of one or two in a hundred live births, genetic problems seem a minor part of the history of death; crucial to a few, but irrelevant to the many. For such rare diseases rests do pay, to use that term in its crudest sense, because of the effectiveness of pre-natal diagnosis and pregnancy termination. In Holland the national counselling service costs about thirty million pounds a year. It prevents the birth of from eight hundred to twice that number of severely handicapped children. Even in that small and efficient system, the expense of their lifetime healthcare would be between about.1 tjuarrer and three-quarters of a billion pounds. For Untjiii, with a population four times as great, the figures must be multiplied in proportion. In the United States, for fragile X syndrome (a common cause of inborn mental defect) the cost of prevention of a single birth is $12, 000 compared to the million-dollar cost of support.