Reproductive cloning and the future of humankind
The ghost of Dolly is watching over a new science
Terry Wuerz Volunteer Staff
Reproductive cloning first received near-galactic media attention in 1997, due to the successful cloning of Dolly the Sheep. The scientific field, at the frontier between science and philosophy, is fraught with ethical challenges yet is almost sure to advance to the successful cloning of a human being in the near future.
Before the past decade, the idea of creating another human being through means other than sperm-on-egg fertilization (via sexual intercourse, preferably) was largely the realm of gruesome science fiction. In the novel The Boys From Brazil, cloning technology is able to bring a copy of Adolph Hitler into the world.
Human cloning contributes chillingly to the dystopic society of Huxley’s 1932 classic Brave New World. Much more recently, Hollywood film The Island explored the idea of using clones as health insurance, for use in organ transplantations. With Dolly dead since February 2003, old before her time, what is the reality of human reproductive cloning today?
Normal human reproduction takes place between a male sperm and a female egg, each with 22 regular chromosomes and one sex chromosome, X or Y. The result is as easy to predict as simple addition: a “somatic” or adult cell that has 44 regular chromosomes and 2 sex chromosomes, from which the rest of our body’s cells divide. If the sex chromosomes are 2 Xs, it’s a girl; if there is one X and one Y, you’ve got a boy.
Reproductive cloning involves neither sperm nor eggs. It takes a somatic body cell from one donor, with 46 chromosomes all-together, and makes that cell divide into all the body’s cells. The result is an entity that has the exact same chromosomal makeup as its donor, as opposed to having half of its chromosomes from its father and half from its mother.
Nevertheless, humans created in this way would not be identical to each other. Experience is a powerful shaper of personality. A clone would be only as similar to its donor (or other clones created with the same donor) as identical twins raised separately. Even if Adolph Hitler were cloned, the chances of him building another Third Reich are infinitesimal.
As for Dolly the Sheep, she was scientifically conceived in Scotland with the ostensible goal of finding a way to genetically engineer therapeutic proteins into the milk of livestock. This would ultimately allow the drug industry to farm milk-producing animals to pump out drugs for cheap.
Dolly the Sheep was cloned using a technique called Somatic Cell Nuclear Transfer, or SCNT. The nucleus of a cell contains the vast majority of the genetic material in a cell, and is the architectural blueprint from which all the cells in our bodies are constructed. To perform SCNT, a geneticist actually isolates just the nucleus of a somatic cell, and manually transfers it into an unfertilized egg (which, in turn, has had its nucleus removed or destroyed). The egg is then artificially implanted into the uterus of a mature female, who carries the embryo to term.
Confused? So are modern cloning technologists. The biochemistry involved in activating the egg that has received its new nucleus is not understood. Many eggs must be expended just to have one make it to birth; most will die in the uterus. This is enough of a practical barrier when sheep are involved. When it is human eggs that are needed, ethical and resource issues are compounded. A highly-trained technologist is required to manually implant the somatic nucleus into the egg cell, and this is extremely resource intense. In addition, Dolly died at a very young age for a sheep, and it is likely that her cells underwent the biochemical process of aging at an accelerated rate.
For these reasons, human reproductive cloning is extremely costly and very risky to the clone. The birth of Dolly has also engineered a new wave of ethical concerns in the public eye. Several scientists have announced that they intend to clone humans for reproductive purposes. This prospect has resurrected a scientific field long fallen in disgrace from popular favour: eugenics.
Called the “self-direction of human evolution,” eugenics sought to improve the human condition by direct intervention. Proposed methods in the past have included birth control, selective breeding, even genocide. The movement was used as a rationalization for the governmental discrimination of “racially impure” Germans during the Holocaust: homosexual people, the Roma and Jewish people. After World War II, eugenics quickly became a societal taboo.
Today, humankind is again faced with the moral dilemma of whether we should have a more controlling hand in our own evolution. The future technologies of human reproductive cloning and genetic engineering have not only revived the field of eugenics, they may offer a chance to improve our genetic makeup. It is likely that, in addition to being disadvantaged from birth, the earth’s poor will someday be genetically deficient as well.
There is a great deal of hope invested into the field of human cloning. Many believe that, in addition to providing an avenue to a cheaper source of drugs, it will one day lead to a discovery that will cure cancer, dispel the plague of organ transplant shortages and even offer a novel solution to human aging. At this point, however, just how profoundly Dolly the Sheep, and the science that made her, will affect our future still lies within the tomes of science fiction.
Terry Wuerz is a third-year medical student.
