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When one of those single-celled embryos divided into two cells, the first step in development, the scientists quickly separated the cells, creating two different embryos with the same genetic information. (This sometimes happens naturally inside a mother, and the result is identical twins.) In the process, though, the researchers had to strip away an outer coating, called the zona pellucida, that is essential to development. Then came the trickiest part of the procedure. Over the years, Hall had been working with a gel derived from seaweed that could serve as a substitute for the zona pellucida. When Hall put the artificial coating around the cloned embryos, they began to grow and develop. The experiment was a success.
The scientists replicated their procedure many times, producing 48 clones in all. That was the entire experiment. None of the clones grew for more than six days. The scientists had no intention of starting an embryo factory, selling babies or doing anything else that ethicists worry about.
In fact, Hall and Stillman were totally taken aback by the furor they created. TIME correspondent Ann Blackman asked Hall if he feared that his work would create a backlash against this kind of research. "I revere human life," said Hall, his voice choking with emotion. "I respect people's concerns and feelings. But we have not created human life or destroyed human life in this experiment." To Hall and Stillman, human cloning is simply the next step in the logical progression that started with in-vitro fertilization and is driven by a desire to relieve human suffering -- in this case, the suffering of infertile couples.
That is certainly the least controversial of the technology's potential applications. In the TIME/CNN poll, Americans were evenly split on whether they approved or disapproved of cloning for this purpose. If it works -- and that is still a big if -- it could probably find a market among infertility patients who have tried everything else. "It's pretty scary," said Barbara Tilden, a 39-year-old Illinois woman who has gone through eight different infertility treatments in the past 10 years. "But I'd probably consider it as a desperate last attempt."
Arthur Caplan, director of the Center for Bioethics at the University of Minnesota, could conjure up several equally defensible ways in which cloning human embryos might be medically appropriate. Suppose, for example, a woman knew she was about to become sterile, either because of chemotherapy or through exposure to toxic substances. She might consider having an embryo cloned for future use. Or suppose a couple knew that their children had a chance of inheriting hemophilia or cystic fibrosis. Researchers have developed DNA-analysis techniques to screen embryos for such disorders, but the procedures require snipping cells off embryos, a process that sometimes kills them. In such situations, having a couple of extra clones around could mean the difference between passing on a defective gene or giving birth to a perfectly healthy child.