When the Wall Street Journal asked business leaders whether they would clone themselves if the technology became available, most said yes. Albert Dunlap, CEO of Sunbeam Corporation, said he would like to have 12 copies of himself, because he could think of 12 companies that could use his help to restructure. "You could have 12 fantastic turnarounds," he said.
Is Dunlap right in his assumption that his clones would possess his business savvy? If you could drop a few skin cells into a cloning machine and have your spitting image stroll out the other side, would you do it? Would your clone walk, talk, or behave like you?
If you have ever known a pair of identical twins, you already have part of the answer. Identical twins share their entire genetic endowment, just as you would with your clone. In fact, identical twins are real life clones. While twins generally look alike and may share many habits and traits, they also have different hopes and aspirations and follow different paths.
But your clone would be even more different from you than a twin sister or brother. The Journal's question assumed that technology will someday make it possible to produce photocopies of ourselves, pre-aged and suffused with a life history and a mature consciousness. In fact, this will never be possible.
The cells in the body of a typical college student, for example, have taken nearly two decades to reach their current state. Stem cells (undifferentiated precursor cells that generate your skin and other tissues) have divided thousands of times, making adult skin tougher and coarser than baby skin. Your immune system has evolved to resist thousands of diseases, and your brain and nervous system have grown and developed in response to a lifetime of experience. None of that was in your DNA when you were born. If technology existed that could clone you, your genetic double would have to begin at the beginning, as an embryo. Your twin would be 20 years younger than you, growing up in a different home, a different school, with different friends, fashions, music, and customs. In 20 years, you might not even recognize yourself.
So far, no one has cloned a human being, but scientists have been cloning animals since the 1950s. The reason for early cloning attempts was to find out whether all cells retain their complete genetic potential as they divide and specialize to form tissues such as skin, blood, and brain. Beginning with amphibians, scientists replaced the nuclei of a frog egg with nuclei from the cells of an embryo, tadpole, or adult frog. Eggs transplanted with nuclei from young embryos nearly always developed into normal tadpoles. But nuclei taken from older embryos and from tadpoles produced progressively fewer tadpole clones. In some cases the egg did not even divide once. Scientists eventually succeeded in generating swimming tadpoles with nuclei taken from adult frog skin, but these tadpoles always died before metamorphosis. It appeared that nuclei from specialized cells were somehow different from the nucleus of an egg.
Cloning adult animals finally became a reality in 1997 when Ian Wilmut, a biologist in Scotland, announced the birth of Dolly, a lamb whose genetic constitution had come from cells of her "mother's" udder. Cloning itself was not new. For years, agricultural biologists had been cloning sheep, pigs, and cattle-but only from the cells of very early embryos that had not yet implanted in the mother's uterus.
In order to clone an adult, Wilmut and his colleagues found that they had to trick the donor cell into behaving as if it were part of an early embryo. By growing the mother's mammary cells in a dish with a limited supply of nutrients, the researchers found they could push the cells back to a less specialized state. Wilmut's cloning success proved that differentiated cells have not necessarily lost their genetic potential.
But is animal cloning useful? Some biotechnology companies think so. These companies already genetically alter farm animals to produce proteins for treating cancer and other diseases, or to create organs for human transplant. Now they have taken an interest in cloning as a way to make copies of mature animals with laboriously constructed genotypes. But others are waiting to see if the technology can be perfected. The Scottish team had to transplant some 300 nuclei to get just one lamb.
Should cloning ever be tried in humans? Wilmut has said he finds the idea morally repugnant and sees no reason even to try. Others object based on the possibility of selecting a nucleus with damaged DNA, which might produce a clone with a genetic disease. Nonetheless, nightmare visions of hordes of mutant drones manufactured to perform menial tasks for a leisure class are probably exaggerated. Cloning human beings would merely produce more human beings with the same natural revulsion to enslavement we all possess.