The Sheep That Shook the World
Ten years ago this week, in late February 1997, word began to spread of a seemingly fantastical advance in biological science. Working in secrecy at the Roslin Institute in Scotland, a small team of research scientists, led by Ian Wilmut and Keith H. S. Campbell, had managed to produce the first living clone of an adult mammal. They had made nearly 300 attempts, and one successful cloning had taken place. The result was a sheep named Dolly, whose DNA exactly replicated that of another sheep six years her senior.
The official announcement of this achievement took the form of an academic paper published in the British journal Nature, titled “Viable Offspring Derived From Fetal and Adult Mammalian Cells.” With this paper Dr. Wilmut and his colleagues took a major step forward for science and technology—and sparked an international debate about the ethics of modern biology.
The cloning of Dolly capped a long century of developments in biology and reproductive science. The previous decades had seen the proliferation of new technologies of birth control and the introduction of reproductive methods such as in vitro fertilization. Dolly was the first animal created as an exact copy of a mature animal, but scientists had previously managed to achieve another kind of cloning, using a mixture of male and female genes to artificially make multiple animals that were identical to one another although not to any already living creature.
Attempts at Dolly-type cloning had faltered when scientists had been unable to create a stable cell by implanting mature DNA into the emptied nucleus of an embryo. The Roslin Institute scientists succeeded where others failed because they developed a method for DNA implantation that synchronized the biological cycles of the embryonic cell with those of the implanted DNA, allowing for a stable and more normal merging than had previously been possible.
Dolly was not created as a mere test of scientific capability or demonstration of human ingenuity. Dr. Wilmut and his collaborators had high hopes for her and her kind, though their motives were largely overlooked in the intense reaction to the announcement. They wanted animals like Dolly to be genetically engineered to produce proteins in their milk that could be used by humans to fight disease, and to strengthen the gene pools of agricultural animals. Thinking even further ahead, there was some hope that animals might even be designed to contain “humanized” organs that could be transplanted into sick people. Wilmut, Campbell, and the other scientists in Scotland would be subjected to intense scrutiny and a hailstorm of public criticism, but their aims in producing a clone were, they felt, noble.
Nevertheless, the public that first heard of Dolly was far from comfortable with the news. The notion of human beings tinkering with the process of creating life has always made people uneasy. When Dolly was announced, Richard Nicholson, the editor of the British Bulletin of Medical Ethics, wrote of an unsettling “Frankenstein factor” in the artificial creation of life. Philosophers and theologians expressed unease, and one professor told the Minneapolis Star Tribune, “It’s an appropriate occasion to be ambivalent about science.”
Still, it was clear that the creation of mammalian clones would provide scientists with important new information about aging and early embryonic development, and that the technology might have serious value for medicine. President Clinton, who had previously taken stands against embryonic research, asked his bioethics advisory panel to perform a 90-day study of Dolly’s creation and report on its implications. In the decade since, no successful effort has been made to ban cloning in the United States, as the potential benefits for research have kept the Senate from passing bills to limit the new scientific field.
At the center of this public debate, if necessarily completely unaware of it, was Dolly herself. While the world struggled with the moral and ethical implications of her birth, her own principal struggle was to keep down her weight. She was housed alone, not out of any experimental need for isolation but because she was bad at sharing food and space. Like her namesake Dolly Parton (who said, on first hearing of her, “There’s no such thing as baa-aa-aad publicity”), the animal loved attention. Unfortunately for her, tests in 1999 showed that her cells appeared more worn down than those typical of a sheep her age, which began to raise questions about the long-term viability of cloned animals. In 2003 she died at the young age of six, and although Dr. Wilmut claimed that her premature death had nothing to do with her cloning, questions remain about how cloning affects the health of DNA.
The public debate about cloning continues, but with less intensity and virulence than when it started in 1997. In 2003, after her death, Dolly was taxidermied and put on display at the National Museum of Scotland, in an exhibit marking the fiftieth anniversary of the discovery of DNA, and thus remained a part of public life. And as The New York Times noted, “Dolly is survived by six lambs, produced the customary way, with a ram.”