now been successfully cloned from adult or fetal cells, and attempts are being made (so far without success) to clone monkeys, dogs, horses, and other animals in the same way. The cloning of mammals involves a process called nuclear transplantation or somatic cell nuclear transfer (SCNT). In biological terminology, clones are not replicas of each other, but contain identical genetic material.
The nuclear transplantation procedure is also used for a purpose distinctly different from cloning whole mammals. Like reproductive cloning, the process of nuclear transplantation to produce stem cells (also called “therapeutic cloning, nonreproductive cloning, or research cloning”) involves placing the DNA from one mammal into an enucleated egg (an egg from which the chromosomes have been removed). Thereafter, the egg is stimulated to divide. At the blastocyst stage of embryonic development (in humans, a 5-7 day old preimplantation embryo of about 150 cells), its inner cell mass is harvested and grown in culture for subsequent derivation of embryonic stem cells. These cells are then used for scientific and clinical investigations. Neither the cells nor the blastocyst are ever implanted in a uterus, as is required for reproductive cloning and the birth of an animal. Figures 1 and 2 in the Executive Summary illustrate the differences between the techniques of reproductive cloning and nuclear transplantation to produce stem cells.
This report, by a joint panel of the National Academies Committee on Science, Engineering, and Public Policy (COSEPUP) and the National Academies Board on Life Sciences (BLS), focuses on issues raised by the possible application of nuclear transplantation technology to the reproductive cloning of humans.
NATIONAL BIOETHICS ADVISORY COMMISSION
In 1997, after a report announced the cloning experiments that produced Dolly the sheep , President Clinton asked that the National Bioethics Advisory Commission (NBAC), chaired by Harold Shapiro, look at the issue of human cloning. The NBAC’s report, Cloning Human Beings , came to various conclusions, including the following (emphasis added):
“The Commission concludes that at this time it is morally unacceptable for anyone in the public or private sector, whether in a research or clinical setting, to attempt to create a child using somatic cell nuclear transfer cloning. The Commission reached a consensus on this point because current scientific information indicates that this technique is not safe to use in humans at this point. Indeed, the Commission believes it would violate important ethical obligations were clinicians or researchers to attempt to create a child using these particular technologies, which are
Dolly, the world’s most famous and controversial sheep, was born twenty years ago – on July 5, 1996 to be precise. She was the first mammal to enter the world following a process of reproductive cloning, making the event a spectacular scientific breakthrough.
To create Dolly, researchers at the Roslin Institute in Scotland employed a technique known as somatic cell nuclear transfer (SCNT). With SCNT, DNA from the nucleus of an ordinary cell - obtained from anywhere in an animal’s body - is transferred into an enucleated oocyte (egg cell), typically from a different animal.
In Dolly’s case, her DNA came from one sheep’s mammary cell; it was implanted into an egg from another sheep; and the resulting tiny biological entity was implanted into the uterus of yet a third sheep, where it grew until birth.
The result of SCNT is a creature with almost the same genetic potential as the one providing the nuclear DNA. SCNT is thus a powerful, and often effective, form of animal cloning.
Dolly is born! Announcement and reaction
Subsequently, in February 1997, Ian (now Sir Ian) Wilmut and his research team at the Roslin Institute announced Dolly’s birth in the prestigious science journal Nature. This provoked political and ethical debates that have never truly stopped.
Public discussion of cloning gradually receded in prominence as new issues arose to dominate the airwaves and the headlines, notably the threat of jihadist terrorism following the attacks on September 11, 2001. But issues relating to cloning technology remain crucial to debates over biomedical research and its regulation.
The announcement – with a description of the method used to bring Dolly into existence – triggered a feverish worldwide response because of the possible implications for human cloning. It was immediately obvious that SCNT could, in principle, be used to create human babies. Across the world, many countries banned human cloning - often with significant punishments, such as lengthy jail terms, even for attempting such a thing.
The case against cloning
The actual arguments against human cloning are extremely varied, and I cannot elaborate them all here. (I go into more of them, and in far more depth, in my 2014 book, Humanity Enhanced: Genetic Choice and the Challenge for Liberal Democracies).
One common claim is that bringing children into the world in this way is somehow a violation of the natural order, or of human dignity; or perhaps it would be an act of “playing God”. Unfortunately, it can be very difficult to pin down precisely what any of these claims really mean in the context of bioethical debate. I am, for example, sceptical about the existence of anything that can correctly be called “human dignity”.
Some critics fear that children created via SCNT would be subjected to unfair expectations of duplicating the talents and achievements of whoever provided their nuclear DNA. Sometimes the critics speak in terms of the autonomy of the child being violated, diminished or denied, although it can be very difficult to spell out exactly what this amounts to. In Humanity Enhanced, I challenge the idea that children conceived through SCNT would have their autonomy violated – or would somehow lack or lose autonomy – in any sense inapplicable to “ordinary” children.
Some critics worry about a larger social effect, or even an effect on our species, if cloning restricted the diversity of children being born (perhaps because parents and doctors might look for donors with a narrow range of characteristics, such as possessing high intelligence and meeting certain standards of physical beauty).
Yet other arguments acknowledge that reproductive cloning in itself might not have a great social or species-wide impact; however, it’s claimed, cloning could place human societies on a slippery slope toward accepting even more radical technological interventions such as genetic engineering of human traits. On one version of the approach, this would, in turn, set us upon a path to unequivocally horrible social outcomes. Thus cloning supposedly confronts us with a slippery slope to another slippery slope … which seems like a tenuous style of argument.
Though some of these fears may have an element of truth, they are all exaggerated. In my view, which I’ve defended in Humanity Enhanced and other publications, human cloning would not be a seriously worrying action if we could carry it out safely.
To some extent, however, all of this is moot. Over the past twenty years, we have enjoyed success in cloning many mammalian species, but no one has cloned a human being. Indeed, we have been frustrated in efforts to clone other primates such as apes and monkeys.
In the upshot, human reproductive cloning is not yet feasible, and indeed there’s no current prospect that it could be carried out effectively and safely in the foreseeable future. Even if we did conceive a human embryo through SCNT, and we then managed to bring it to term, the odds are very high that the result would be a seriously deformed child.
That’s a good pragmatic reason not to make attempts until we know a lot more, and even then we’d need to have developed the technology to a point where we are about as likely as with ordinary births to end up with a healthy baby.
I don’t rule out that someone might accomplish this technological feat one day, but, once again, there is no sign of it happening. Nor is it what SCNT research is really about from the point of view of reputable medical researchers. The real action is with what is known as “therapeutic cloning”. Allow me to explain.
Reproductive and therapeutic cloning
So far I’ve focused on “reproductive cloning”, and more specifically on human reproductive cloning: the postulated use of SCNT (or any other technique that might have a similar result) to bring about the birth of a human child.
By contrast, the expression “therapeutic cloning” refers to the creation of human embryos by SCNT for some other purpose, such as for biomedical research or for harvesting cells or tissues to be used in therapies.
Although some ethical issues are raised with therapeutic cloning – including a concern that the associated research destroys human embryos – the idea has been obtaining legal acceptance in some countries, usually subject to tight government regulation. If we start to see impressive results from therapeutic cloning, with new therapies emerging from the research, I expect that it will eventually obtain the same wide acceptance that IVF – in vitro fertilization – now enjoys in Western countries. (It’s not that long ago that IVF was also widely regarded as abhorrent.)
More generally, people come to embrace new technologies, even those that initially seemed shocking and “unnatural”, once concrete benefits become clear.
Twenty years later
Two decades later, I’m not sure that the ethical arguments advanced for and against human cloning are greatly different from those we saw back 1997. However, the early debate was very one-sided. The initial response to the dramatic Nature article by Wilmut et al. was largely one of fear, mingled with disgust, with too little rational reflection. Since then, the fear-mongering has partly died down, but not before a great deal of draconian legislation was enacted across the world. Little chance was given for calmer voices - or any dissenting voices - to be heard before governments took action.
As it seems to me, calmer voices eventually won the academic debate. There is a strong sense, within the field of secular bioethics, that the early arguments against human reproductive and therapeutic cloning were flawed. However, dissenters lost the political debate almost before it began. Politicians, journalists, many academics, and the general public in our Western liberal democracies greeted the very idea of human cloning with a cascade of hostility.
The expressions of fear, disgust, and moral outrage appeared immediately; in response, highly illiberal laws were enacted without due consideration of the issues.
But more reasonable people are slowly winning back the central political ground, gradually making the public case that technologies based on SCNT may bring many benefits. That, perhaps, will be the story of the next twenty years.