October 16, 2007 > TechKnow Talk
Human Cloning: Miraculous or Monstrous?
We have all wished we could go fishing while our clone went to work or tended to an unpleasant chore. We've also heard the horror stories regarding the potential future of cloning: endless ranks of identical soldiers, rampaging re-animated dinosaurs, or rooms full of brainless, breathing bodies of human "spare parts." What is cloning, what is the current state of research, and what are some of the moral implications surrounding this often-misunderstood subject?
There are several types of cloning. First, recombinant DNA or DNA cloning has been used for several decades in genetic and medical research. This type of cloning replicates genes or small sections of chromosomes. A common laboratory procedure, it creates no embryo or other potentially viable organism; no reproductive tissues are employed. For these reasons, recombinant DNA is not as controversial as other cloning techniques.
The second cloning technique, reproductive cloning, is very controversial indeed. The purpose of reproductive cloning is to create a new animal using the genetic blueprint of a single DNA donor rather than the combined DNA of two parents. In simplistic terms, this is accomplished by extracting an egg, or ovum, from a female donor, removing the nucleus of the egg, and replacing it with a cell from a DNA donor. The cell and egg are fused together and "kick-started" with an electrical shock. If the procedure is successful, the cell will begin to divide and form an embryo that can then be implanted into an adult female for gestation. The offspring will have nearly identical genetic material as the DNA donor.
Reproductive cloning of animals dates back to 1952 when tadpoles were successfully cloned. In recent years, many more complex animals have been cloned including mice, cats, rabbits, pigs, and cows. Researchers in Scotland garnered a great deal of media attention in 1997 with a cloned sheep named Dolly. In late 2006, the Food and Drug Administration declared meat and milk from cloned animals to be safe for human consumption. However, due to the expense of cloning farm animals, it is unlikely much if any such food will appear in supermarkets any time soon.
In fact, the cloning process for mammals is very difficult, and success rates are low. Typically, less than one percent of cloning attempts survive to birth. There is evidence that cloned animals also tend to be less healthy than their naturally-conceived counterparts, suffering from increased rates of deformities, premature aging, immune deficiencies, cancer, and other diseases. Dolly the sheep was euthanized in 2003 after contracting arthritis and lung cancer, having attained about half the normal lifespan for her species.
Considerable research has been performed in the field of monkey and human reproductive cloning, primarily in Europe and Asia. Despite several unsubstantiated claims, there is no hard evidence that anyone has ever succeeded. Because of the poor embryonic survival rate and the high risk of birth defects and disease in animal clones, the majority of scientists are ethically opposed to any further research in human reproductive cloning.
A third type of cloning is therapeutic cloning. The goal of therapeutic cloning is to create stem cells. The process is similar to reproductive cloning, but instead of implanting the embryo (or pre-embryo) into a female, it is used to extract embryonic stem cells, which have the unique capability of producing any type of specialized cell: skin, heart, liver, etc. Again, tissues produced in this way are genetically identical to the DNA donor, so such organs transplanted into the donor would be perfect matches, eliminating the common (and typically fatal) problem of transplant rejection.
Harvesting stem cells destroys the embryo. Thus therapeutic cloning also presents ethical and moral concerns. While some scientists argue the embryo is nothing more than a collection of a few cells when it is destroyed, opponents maintain that it nevertheless holds the potential for a human life.
While therapeutic cloning for humans is still in the research stage, it has demonstrated tremendous promise for eliminating many of the myriad difficulties with organ transplants such as locating suitable donors, long waiting lists, often debilitating anti-rejection therapies, etc. Embryonic stem cells also have the potential for application in the treatment of a much broader variety of diseases, including diabetes, Parkinson's disease, and Alzheimer's.
Several countries have enacted legislation to prohibit or restrict various types of cloning. For example, human reproductive cloning is illegal in the UK, though therapeutic cloning research is allowed. Australian laws are similar. Here in the U.S., the Bush administration is adamantly opposed to all cloning research. Though no federal law currently prohibits it, many states have banned both reproductive and therapeutic cloning.
Therapeutic cloning is the focus of the majority of current research, but when most of us think of cloning, it is reproductive cloning that comes to mind. Though human reproductive cloning may be the stuff of science fiction, at least for now, the implications are worth considering. It is one of a handful of fields of scientific endeavor that brings into sharp focus the tension between the advancement of scientific knowledge and the exercise of religious and moral principles.
Suppose humans are someday cloned. What would your clone be like? Since he or she is essentially identical genetically, your clone would look as much like you as an identical twin, though there would of course be an age difference. Would your clone think, feel, and act as you do? The answer depends on how much personality is formed by genetic influence and how much by environmental factors. This "nature vs. nurture" debate is ongoing, but there is compelling evidence that identical twins raised apart are often very similar in personality, so clones would likely share similar personality traits as well.
There are many potential applications of human cloning, from the relatively mundane to the bizarre. If a couple is unable to have a child naturally, one could be cloned from the DNA of either the man or the woman. Most of us might be comfortable with that, but what if the couple instead chose the DNA of a favorite aunt or a best friend to clone their "child?" What if they recovered DNA from a natural child lost to accident or illness to clone an identical replacement?
Suppose they paid a mathematical genius or musical prodigy to be the DNA donor? In theory such a person, whether gifted with superior intelligence, the beauty of a model, or some other desirable attribute, could produce thousands of identical offspring from a single swab of the mouth or a skin scraping. Should that person be allowed to sell DNA to anyone who can afford it? How many "copies" of that person are too many?
If enough DNA could be recovered from the bones of the long-dead, should there be laws against cloning them? Should clones be created of Jefferson, Einstein, or Da Vinci? What about Hitler? Would you be comfortable with your daughter giving birth to your grandfather's clone? Would the child be your grandfather, your grandson, both, or neither?
Beyond human cloning, is it ethical to clone a favorite pet? Many people have already paid a private company to clone their cats. Assuming enough DNA could be recovered, should we create clones of extinct or endangered animals to increase their chances for survival? If we could, should we clone dinosaurs? Extinct animals would present the added difficulty of finding a suitable animal to carry the fetus to term.
While the potential implications of reproductive cloning are entertaining, the morality of therapeutic cloning is more germane to the current political debate. If we can save lives by producing stem cells in this way, does that outweigh the moral qualms associated with creating and destroying embryos? If you needed a liver to save your life, would you condone growing it from embryonic stem cells? Would your answer change if it were your spouse or your child who was dying?
The public policy debate surrounding cloning continues. Whether one's opinions derive from scientific evaluation, religious faith, philosophical conviction, moral judgment, or some combination of these, an informed and thoughtful position is needed to engage effectively in that debate.