Cloning is the asexual production of an exact copy of an original. So for example, one could use cloning to produce the exact copy of a single cell. The cell copy would be identical to the first cell and would have the same exact DNA sequence. In many cases, cloning has been used to reproduce type specific cells. In some instances, cloning of an individual organism, like the sheep, Dolly, has been possible.
Unlike reproduction that involves two “parents,” such as a male and female plants, cloning has a single parent. This is often used in reproducing certain plants. Certain plants have undergone cloning processes for thousands of years, but they do not play a part in the ethical debates that surround cloning of animals, and most particularly humans.
For example, reproductive cloning of animals was first attempted in the 1950s. Most identify the sheep Dolly, cloned in 1996. Dolly’s parent had DNA transferred into an egg that had its nucleus removed. This is called a somatic cell nuclear transfer. The cell was then treated with chemicals and stimulated to grow so than an almost exact replicate of the cloned sheep was born.
In actuality, Dolly was not a precise clone of her parent. She shared the same DNA, but some of the genetic materials of the donor cell also became part of Dolly’s parentage. This is only .01% of Dolly’s DNA, but it does make a negligible difference.
The cloning resulting in Dolly was not exactly simple. In fact it took 277 donor eggs, and the production of 29 embryos before a live birth was achieved. Calf cloning experiments with somatic cell nuclear transfer have prospered less than 1% of the time.
However, the idea of cloning humans still remains. While many people feel that cloning human tissue, as for organs for transplant might be valuable, many others feel that cloning a whole human is unethical. Some scientists without religious affiliation also believe that ethical issues that might be engendered in prolonging life through cloned tissues need further scrutiny.
From a moral standpoint, much has to do with how some reproductive clones are made. Many believe that an embryo, even when simply fertilized sperm and egg is a human and thus should not be destroyed. Experimentation of embryos to produce clones often results in embryo death. Further some feel that cloned embryos might be used specifically to harvest body parts and then killed.
Some further feel that the harvesting of stem cells from an embryo is also wrong, or that creating embryos for the purpose of harvesting stem cells is unethical. Others argue that stem cell research may point the way toward curing diseases for which there is currently no cure. It should be noted, however, that fewer people object to the idea of cloning a body part, than cloning a human.
Others are concerned about the cloning of extinct or endangered animals. In fact Michael Crichton’s novel Jurassic Park dealt with this theme extensively. Especially since actual dinosaur DNA has been found recently, in enough abundance to clone, some scientists are concerned about the environmental impact that could result from reproducing a long dead species.
In some countries, stem cell research has been halted, when it involves cloning human embryos. Other scientists investigate the possibility of finding stem cells elsewhere, as in the umbilical cord blood of newborns. It is suspected that some countries may be attempting to clone a whole human, but have not yet achieved this.
Though cloning is much in the news, it is still an imperfect science with more failures than successes at present. This suggests that scientists may not fully understand all the mechanisms involved in creating an exact copy of another organism. With further research, such mechanisms may be understood and clear the way toward making clones. Yet, doing so is likely to result in continued controversy.
By Tricia Christensen