When the now-famous Scottish sheep that carried the astonishing news that Ian named Dolly was introduced to the Wilmut and his colleagues at the Roslin world earlier this year, the world responded Institute, near Edinburgh, had cloned Dolly with a giddy mixture of levity and alarm. "An from the udder of a six-year-old ewe. udder way of making lambs" said a headline "We should be clear why the science of in the same issue of Nature (Feb. 27, 1997) Dolly is so important," John Maddox, a former Nature editor, writes in Prospect (Apr. 1997). The cells in an animal’s body undergo a gradual process of specialization as the embryo develops into a newborn animal, so that while each cell in the animal’s body has a full complement of DNA, each uses only those genes needed for its specialized function. Scientists thought that the unused genes were somehow permanently switched off. Dolly refutes that. She shows that an animal replica can be grown from the DNA in just about any cell in the body.

What Wilmut and his colleagues did, explains Science News (Apr. 5, 1997) writer John Travis, was to take mammary cells from a ewe and deprive them of nutrients, so that the cells entered a "quiescent" stage. The researchers then fused these cells, containing all their DNA, with egg cells whose nuclei had been removed. The developing embryos were then implanted in a surrogate mother. Out of 277 attempts to produce a clone in this way, Wilmut and his associates succeeded only once. (Helping to ease doubts that Dolly might be a fluke, researchers at a Wisconsin firm disclosed to New York Times [Aug. 8, 1997] science writer Gina Kolata that they have cloned genetic replicas of more than 10 adult Holstein cows. Though none of the clones had yet been born, some of the cows were expected to deliver "very soon," and the researchers were confident of success.)

"In one sense," observes Travis, "Dolly isn’t even a true clone—she does not share all of her genes with her donor." While the nucleus was removed from the egg cell that became Dolly, the energy-producing mitochondria, home to a few dozen genes, were not. Is this mixing of genes important? Scientists do not know. "Nor do they know whether Dolly will be fertile or have a normal life span." The nucleus from which she was created was from a six-year-old ewe; was the age of the transplanted nucleus "reset"? If not, Travis says, "Dolly’s life might be historic but brief."

Despite the uncertainties, the cloning of animals may benefit humans. The Roslin research, for example, has been underwritten by a Scottish biotech firm seeking to genetically alter female animals so that they secrete valuable drugs—such as human hormones or other biological products to treat disease— in their milk. In July, the scientists announced that they had produced a lamb called Polly with a single human gene in every cell of its body—a lamb cloned from a fetal cell that had that human gene implanted in it, reports Gina Kolata in the New York Times (July 25, 1997).

Cloning technology may also allow scientists to give sheep and other animals human diseases, for study and testing. Researchers might also be able to produce pigs tailored to generate organs suitable for transplant into people. It is even possible, when the process for reversing the specialization of tissue cells is better understood, that whole organs such as human livers could be regenerated.

What about cloning humans? The nightmarish possibilities are readily apparent, observes Tabitha M. Powledge, a science journalist writing in Technology Review (May–June 1997). "Consider, for example, a world without sex because cloning does away with fathers. Or endless duplicates of individuals—Nobel laureates, movie stars, criminal masterminds, fascist dictators, whoever—created with or without their knowledge. Or how about raising the dead, literally, from the cells of corpses?" Some are optimistic about the future of cloning. Biologist Francis Crick, codeveloper of the double-helix model of DNA structure, and 30 humanistic scientists, philosophers, and others signed a declaration in Free Inquiry (Summer 1997) expressing confidence that human reason will be able to resolve any "moral predicaments" that cloning humans may bring. But Leon R. Kass, a physician-philosopher at the University of Chicago, writing in the New Republic (June 2, 1997), contends that cloning humans would be unethical and dangerous. "Asexual reproduction, which produces ‘single-parent’ offspring, is a radical departure from the natural human way, confounding all normal understandings of father, mother, sibling, grandparent, etc., and all moral relations tied thereto. It becomes even more of a radical departure when the resulting offspring is a clone derived not from an embryo, but from a mature adult to whom the clone would be an identical twin; and when the process occurs not by natural accident (as in natural twinning), but by deliberate human design and manipulation; and when the child’s (or children’s) genetic constitution is pre-selected by the parent(s) (or scientists)." At issue, Kass believes, is nothing less than "the future of our humanity." He favors a legal ban on the cloning of humans.

President Bill Clinton agrees. Human cloning, he said in June, "has the potential to threaten the sacred family bonds at the very core of our ideals and our society." He is backing his National Bioethics Advisory Committee’s recommendation for legislation "to prohibit anyone from attempting, whether in a research or clinical setting, to create a child through somatic cell nuclear transfer cloning." These alarms may turn out in the end to be false. Cloning humans by the method used to produce Dolly may be impossible, the Economist (Mar. 1, 1997) notes. The transplanted DNA may need to be "reprogrammed" before it can work. In a sheep’s embryo, the DNA does not start controlling the new organism’s development "until the egg has divided three or four times." In humans, the DNA must take control much sooner—after the second cell division. This may not allow enough time for the transplanted DNA to be reprogrammed.

If human cloning should be at all possible, however, it "cannot be prevented" from being done somewhere in the world, argues James Q. Wilson, author of Moral Judgment (1997). Cloning’s major threat, he writes in the Weekly Standard (May 26, 1997), would be to the already besieged two-parent family. If cloning were allowed only for two married partners, and the mother, in normal circumstances, carried the fertile tissue to birth, then, he thinks, the gains ("a remedy for infertility and substitute for adoption") would outweigh the risks. But that, of course, is a big if.