Do not cower from science

The news that biologists have successfully cloned sheep is cause for hope, not fear, says Tom Wilkie

For more than 10 years now, the solemn and serious Fellows of the Royal Society, Britain's national academy of science, have been preoccupied with increasing public understanding of science. Judging by the reaction to the news this week that biologists at the Roslin Institute in Edinburgh have cloned sheep, they have clearly failed.

Bafflement tinged with fear appears to have greeted the sight of sheep that have been brought into this world by a process other than traditional sexual reproduction. The cry has gone up: will the men in white coats do next to us what they have done to the sheep? And there have been the inevitable hackneyed references to Hitlerian eugenics and "playing God".

The limits of the biologically permissible have been raised in more measured tones elsewhere this week. The seriously intelligent and reasonable Nuffield Council on Bioethics has published a report on the moral acceptability of using genetically engineered pigs as "donors" of organs to be transplanted into people when suitable human organs are not available. And on Wednesday, the House of Commons Select Committee on Science and Technology spent an agreeable couple of hours grilling the Minister for Science, Ian Taylor, on why the Government has no policy to cope with the avalanche of new discoveries made by researchers teasing through the long double helix strand of human DNA to read all the genetic messages encoded in that molecule.

The birth of five Welsh mountain lambs, each derived from the same single set of genes, unquestionably represents a technical tour de force in mammalian embryology. Although three died soon after birth, the survival of "twins" nicknamed Megan and Morag visibly demonstrates the high scientific skills of the team at Roslin.

Yet impressive though this feat is, it has important scientific limitations. Characteristically, these have been ignored by many commentators worried about setting moral limits to what the scientists do.

Scientists have been cloning animals in the laboratory for decades. Mammals are much more difficult, admittedly, than frogs or toads but the first healthy live lambs to be produced by a cloning technique were born more than 10 years ago. It is also nearly 10 years since a "chimaeric" mammal - a cross between a sheep and a goat that could never have come into being without the techniques of genetic engineering - was born in Cambridge. So is any fuss now really justified?

At the very beginning, the Roslin lambs started their journey to life in the traditional manner: with a ram tupping a ewe and its sperm mingled with the ewe's egg. But nine days after fertilisation, when the single- celled egg had grown to a little clump of 16 cells, the researchers intervened and dissected out the "embryonic disc" - the part that would otherwise have been destined to grow into a lamb rather than, say, placenta. The researchers cultured the cells from the embryonic disc in the laboratory, persuading them to continue to live and grow. The establishment of this "cell line" is one of the most important achievements of their work.

In effect, from one fertilised egg they now had a "clone", a collection - which they could make as large as they liked - of genetically identical cells available in the laboratory glassware. If one cell gave rise to the "birth" of an animal that proved particularly valuable, it would be possible to produce hundreds of identical copies as long as the other cells had been kept in culture. And, when genetic engineering becomes sophisticated enough, it might be possible to insert DNA leading to desirable characteristics directly into the cells.

Nor need the applications be restricted to farm animals. What would Elvis Presley and those of us who wept with him over the death of "Old Shep" have done if it had been possible to produce that beloved dog in this way? If the original cell line from which Shep sprang had been kept going in the laboratory, Elvis could have ordered up a replacement "Shep" - identical in every way to the original new-born puppy that grew into the dog he loved.

But Elvis could not have cloned his dog by taking one of Shep's body cells just before he blew the animal's brains out. Shep's cells were all "differentiated" - they had in effect already chosen to be nerve or muscle or skin cells and not any other sort. The Roslin researchers had to use cells from a very early embryo because only these cells arecapable of developing into every other type and thus forming all the tissues of a living individual.

For the same reason, clones of Elvis himself or even of Hitler would have been impossible. It may one day be possible to clone from differentiated cells, but no one yet knows in principle how to do so.

It is possible in principle to apply the Roslin technique to humans. But some future Hitler could clone copies of himself only if, at the moment of his conception (years before anyone could ever know that he would become a megalomanic dictator), some of his totipotent embryonic cells had been cultured and that culture maintained until his megalomania became evident.

As is to be expected in new scientific research, the overall success rate of the Roslin work - in terms of live births compared with numbers of manipulated embryos - is poor. The prospect that we might one day see "monocultures" of genetically identical sheep or cattle, selected to give leaner meat or healthier milk, will depend crucially on the efficiency and cost of the Roslin process compared with conventional breeding techniques. It will be years before such costs become clear.

Cloning humans is illegal in Britain. Even were it permitted, it is unlikely to replace conventional methods. After all, Louise Brown, the world's first human test-tube baby, is now nearly 18 years of age, yet IVF is sought only by those with a compelling medical reason. The rest of us have yet to be wooed away from the more traditional method.

The late, great British medical researcher Sir Peter Medawar noted in a essay written at the beginning of the era of genetic engineering and recombinant DNA: "It is the great glory, as it is also the great threat of science that everything which is in principle possible can be done if the intention to do it is sufficiently resolute. Scientists may exult in the glory, but in the middle of the 20th century, the reaction of ordinary people is more often to cower at the threat."

There are serious people trying soberly to assess what the scientists are doing and what applications of their work we should permit. Sadly, this sterling work has gone unnoticed by those moral commentators whose reaction to Roslin has been a perhaps secretly enjoyable frisson of fear.

Our own government has been shamefully negligent. When last July, the House of Commons science and technology select committee produced a report on human genetics (internationally recognised as one of the most comprehensible and sensible expositions of the subject), the Government contemptuously rejected its recommendations. The committee's conclusions are detailed; they are complex; and don't fit into convenient soundbites. But they take up Sir Peter's challenge and, in his own words, reply that science offers "the hope of progress" - that we can be in control and we do not need to cower.