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(Issue 3; posted March 6, 1997; archived April 18, 1997)
In the past few days, almost every newspaper in the world has chosen to wring its hands about the supposed ethical dilemma posed by the lamb called "Dolly", the cloned sheep born at the Roslin Institute at Edinburgh a few months ago. How's this for a first approximation to a summary of what all those newspapers should have said: Dolly poses no novel ethical problems, and will not do so for many years.
That is not the outrageously insensitive remark that it may seem. And it does not rest on the simple observation that Dolly is a sheep, not a human being. Even if the technique is transferable to human beings (which is not guaranteed), there is no prospect that even the world's well-heeled megalomaniacs will be cloning themselves soon, or at all.
For one thing, there is the cost in surrogacy. Dolly sprang from one out of 29 embryos implanted in the uteri of 13 different female sheep. To ensure that the embryos had a chance of growing successfully to term, they were first grown to the 4-cell or 8-cell stage. Most of the implantations did not lead to pregnancy. Only the embryo that produced Dolly led to a successful pregnancy and birth.
These are early days, of course, and the technique is certain to be made more efficient with further practice, but it is likely always to be the case that the viability of these artificial embryos will be less than that of embryos formed directly from ova and sperm. After all, the first step in the procedure described by Dr Ian Wilmut and his colleagues (Nature 385: 810-813, 1997; see Endlinks below) is the removal of the nucleus from a mature but unfertilized ovum. Notoriously, ova contain materials required to see the embryo through the first several cell-divisions; taking away the nucleus is bound to remove some of this material as well, reducing the viability of the embryo. Yet the experience of IVF clinics is that even in ideal conditions, the chance of successful implantation of a single embryo is 20 per cent or so. Large numbers of women would be caught up in an attempt at a single cloning of a human being.
Need any of this deter a sufficiently determined (and rich) megalomaniac? There is a further snag. As yet, it is too soon to know whether Dolly's age will start running from the day of her birth, or from the 6-year age of the donor of the mammary tissue from which she has sprung. If, however, the age of an animal is in any way encoded in its genome, there is a high chance that cloned animals produced by the Wilmut technique will quickly assume the age of the donor animal. What megalomaniac would welcome a clone who is a physiological contemporary? When we know how Dolly grows up, such people will be better able to decide what to do.
But the real deterrent to cloning oneself (if one is a rich megalomaniac) is the old conflict between nature and nurture. Although human genetics is going through a phase in which many onlookers and some geneticists (who should know better) are convinced that a person's character and capability is almost exclusively determined by his or her genes, the plain truth is that the environmental influence on development is now, more than ever, largely undetermined.
Yet common observation shows that even historical accidents can make an immense difference to a person's development to adulthood - exceptionally inspiring schoolteachers are frequently mentioned in this connection. And while the obvious class of those who would clone themselves are political dictators and powerful captains of industry, even they would be hard-pressed to bring up their cloned siblings in just the way that made them ruthless. Imagine the disappointment if a dictator's clone turned out to be a libertarian, or if the chairman of some multinational company found that his clone wanted to devote himself to the relief of others' poverty!
This does not mean that we do not have to worry about the ethics of cloning, but in most places the application of the Wilmut technique to people is already forbidden by law. In Britain, for example, it is a criminal offence to experiment with human embryos without a licence, which will not be granted under any circumstances for experiments with embryos more than 14 days old. (There is a strong case for believing that the 14-day restriction is too tight, especially by preventing studies of the teratological induction of neural defects.) To be sure, people might argue that an ovum whose nucleus has been replaced by that of a somatic cell is not a real human embryo, but that seems a flimsy argument. But governments believing it to be their duty to prevent people cloning themselves had better set about negotiating an international convention to make practice uniform everywhere. Otherwise, self-cloners will be off to places like Morocco before you can say "Dolly".
Sir John Maddox is a well-known writer and commentator. He was Editor of Nature, and has been a lecturer in theoretical physics at the University of Manchester.