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Human cloning is the creation of a genetically identical copy of an existing, or previously existing human or growing cloned tissue from that individual. The term is generally used to refer to artificial human cloning; human clones in the form of identical twins are commonplace, with their cloning occurring during the natural process of reproduction.
Although genes are recognized as influencing behavior and cognition, "genetically identical" does not mean altogether identical; almost no one would deny that identical twins, despite being natural human clones with identical DNA, are separate people, with separate experiences and not altogether overlapping personalities. However undramatic it may sound, the relationship between an "original" and a clone is rather like that between identical twins raised apart; they share all the same DNA, but little of the same environment. A lively scientific debate on this exact topic occurred in the journal Nature in 1997. Ultimately, the question of how similar an original and a clone would be boils down to how much of personality is determined by genetics, an area still under active scientific investigation. (See nature versus nurture and cloning.)
Techniques
Currently, there are three types of cloning. The most successful and common cloning technique is the process which allowed Dolly the sheep to be cloned - somatic cell nuclear transfer. It is also the technique used by ACT, the first company to successfully clone a human embryo (see research section below). An egg cell taken from a donor has its nucleus removed. Another cell with the genetic material to be cloned is fused with the original egg cell. Another way of cloning is by parthenogenesis, where an unfertilized egg cell is induced to divide and grow as if it were fertilized. This technique could only work with females.
(The technique known as embryo splitting has the potential to produce a number of genetically identical individuals, but not individuals genetically identical with a pre-existing child or adult. It is often regarded as a cloning technique, but does not meet the definition used in this article.
Purposes
- Purposes of human cloning can best be explained by referring to two kinds of cloning that would both normally use the somatic cell nuclear transfer technique. These are commonly referred to, respectively, as "reproductive cloning" and "therapeutic cloning". - In reproductive cloning, the cloned embryo is implanted in a woman's uterus. This should develop into a normal baby, its only distinction being that it would be almost genetically identical to the DNA donor. Scientific knowledge of normal and abnormal development could also be found. - Therapeutic cloning could be used to provide replacement organs or tissue for people who have had theirs damaged. The cloned embryo would contain DNA taken from the transplant patient. After nuclear transfer, the cell would divide to form an embryo and stem cells would be removed. Stem cells could develop into any tissue or organ. These cloned organs would be compatible with the person's immune system, so no immunosuppressant drugs would have to be taken after the operation. However, no therapies have been developed yet from this procedure.
Limits of cloning
First, none of these techniques provide exact clones — they would be 99.7% identical to the DNA donor, because some important genes are present outside the nucleus, in mitochondria for example. Some of the DNA of the DNA donor would be missing for the clone to be an exact copy, and some of the resulting clone DNA would come from the donor egg-cell. How much change this would lead to in the clone is being investigated. Consider that the chimpanzee genome is more than 98% identical to the human genome, only a 2% difference. A 0.3% difference could potentially lead to much more divergence from the DNA donor's genotype than one may at first believe. It could also spell problems for therapeutic cloning, where compatibility is essential because of the risk of rejection.
Second, difficulties with cloning organisms from their somatic (non germline) cells tend to lead to (what seems to be) premature aging in higher animals. If a new brain is generated in that body, there is no reason to believe that consciousness, apart from the ethics of the move, can ever be moved from one brain into a new brain even if it is genetically identical. Identical twins often show uncanny parallels in life choices, but rarely do they exhibit any characteristics that would cause one to believe that genetic similarities in brains lead to any kind of compatibility of consciousness.Thirdly the process of cloning can only be used to females of the species being clonned. Although this idea recently came into dispute with new controversial theories on the matter all experiments ended in the rejection of the male would be clone. Moreover if a brain is moved from an old body to a new one, even a clone, it would continue to lose size and capacity to regenerate cells, and continue to be subject to such degenerative disorders as Alzheimer's disease. Given all this, "immortality" seems a difficult goal to achieve, and even extended lifespan may be at a low quality of life.
Given these limits, the main reason for interest in the speculations is that they may be driving funding for research, and providing active lobbying for legal or political protections for the cloning industry. Concerns regarding the Raelian movement tend to focus on these issues.
All such issues are likely to be solved with better manipulation of DNA (better copies, able to fix changes which occur with each cell division and accumulate over time — these changes in the parent cause premature ageing in the clone), and better understanding of how DNA changes with each cell division.
Claims of success in human cloning beyond the embryo stage
In 1978 David Rorvik claimed in his book In His Image: The Cloning of a Man that he had personal knowledge of the creation of a human clone. A court case followed. He failed to produce corroborating evidence to back up his claims, and his claims are now regarded as a hoax.
Severino Antinori made claims in November 2002 that a project to clone human beings has succeeded, with the first human clone due to be born January 2003. His claims were received with skepticism from many observers.
In December 2002, Clonaid, the medical arm of a cult called Raëlism, who believe that aliens introduced human life on Earth, claimed to have successfully cloned a human being. They claim that aliens taught them how to perform cloning, even though the company has no record of having successfully cloned any previous animal. A spokesperson said an independent agency would prove that the baby, named Evá, is in fact an exact copy of her mother. Shortly thereafter, the testing was cancelled, with the spokesperson claiming the decision would ultimately be left up to Evá's parents.]
A mother in America plans to pay $500,000 to the Clonaid organization to clone her deceased daughter. In December 2004 Dr. Boisselier, claimed in letter to the UN that Clonaid has successfully cloned 13 children, however their identities cannot be revealed to the public in order to protect them.
On October 9, 2003, newspaper Le journal de Montréal published an article accusing Clonaid and the Raelian organization of maintaining an outright hoax in its claims regarding cloning a human baby.
In 2004 a group of scientists led by Hwang Woo-Suk of Seoul National University in Korea claimed to have grown 30 cloned human embryos to the one-week stage, and then successfully harvested stem cells from them. The results of their experiment were published in the peer-reviewed journal Science.
On May 30, 2005, Hwang's team announced the creation of 11 lines of human stem cells, using a different technique (Hwang et al. 2005).
Later in 2005, a pattern of lies and fraud by Hwang Woo-Suk came to light, removing any of his credibility.
Possible advantages
Many hopes have been put upon human cloning. Therapeutic cloning could provide needed organ transplants. A cure for cancer by a better understanding of the cell-differentiation process, as well as better treatments for heart attacks and improved cosmetic surgery, are being cited as being possible with the new technology. Dr. Richard Seed thinks that human cloning will help us understand, and eventually reverse, the human aging process.
Antinori and Zavos hope to create a fertility treatment that allows parents who are both infertile to have children with at least some of their DNA in their offspring. Some families have high hopes for reproductive cloning. How to Build a Human, a documentary by BBC and The Discovery Channel, illustrated the prospects by showing an American family that wants to make a clone of their third child, who, although genetically healthy, had serious mental and physical deficiencies due to complications at birth and is expected to die soon. Other people hope to clone their already deceased children. Jonathan Colvin, in an interview on the CBC, expressed his desire to clone himself while repairing his genetic defect (cystic fibrosis), thereby creating a version of himself free of the fatal disease.
The current law on human cloning
In 1998, 2001, and 2003 the U.S. House of Representatives voted whether to ban all human cloning, both reproductive and therapeutic. Each time, divisions in the Senate over therapeutic cloning prevented either competing proposal (a ban on both forms or reproductive cloning only) from passing. President George W. Bush is opposed to human cloning in any form. Some American states ban both forms of cloning, while some others outlaw only reproductive cloning.
Current regulations prohibit federal funding for research into human cloning, which effectively prevents such research from occurring in public institutions and private institution such as universities which receive federal funding. However, there are currently no laws in the United States which ban cloning completely, and any such laws would raise difficult Constitutional questions similar to the issues raised by abortion.
The British government introduced legislation in order to allow licensed therapeutic but not reproductive cloning in a debate in January 2001 after an amendment to the Human Embryology Act. However on November 15, 2001 opposition groups won a High Court legal challenge that effectively blocked cloning of embryos for therapeutic purposes. They discovered a loophole which allows reproductive cloning to be performed also. Anti-abortion groups say that a new debate is necessary because of recent technologies having been developed that might circumvent the need for embryonic cloning. The government overruled this attempt at the beginning of March 2002 and currently therapeutic cloning is allowed under license of the Human Fertilisation and Embryology Authority. The first known licence was granted on August 11, 2004 to researchers at the University of Newcastle to allow them to investigate treatments for diabetes, Parkinson's disease and Alzheimer's disease.
Australia has prohibited human cloning, though a government committee is still reviewing issues related to therapeutic cloning and the creation of human embryos for stem cell research.
Organizations devoted to cloning humans, such as the Raelians' Las Vegas-based Clonaid, as well as Antinori and Zavos, are very hard to control. Many think these groups would shift their operations to other countries should mainstream legislation impede their operations, as many less developed nations have no such ban on cloning, so human cloning experiments could (theoretically) be easily shifted to more viable areas. On December 12, 2001 the United Nations General Assembly began elaborating an international convention against the reproductive cloning of human beings. Lawrence Goldstein, professor of cellular and molecular medicine at the University of California at San Diego, claims that the United States, unable to pass a national law, forced Costa Rica to start this debate in the UN over the international cloning ban. In February 2005 a vaguely worded and non-binding United Nations Declaration on Human Cloning was finally adopted. * The European Convention on Human Rights and Biomedicine prohibits human cloning in one of its additional protocols, but this protocol has been ratified only by Greece, Spain and Portugal. The Charter of Fundamental Rights of the European Union explicitly prohibits reproductive human cloning, though the Charter currently carries no legal standing. The proposed European Constitution would, if ratified, make the charter legally binding for the institutions of the European Union.
See also
References
"Human cloning"