AAAS Policy Brief: Human Cloning
New:
AAAS Urges United Nations to Endorse Cloning for Research Purposes (November
3, 2003)
AAAS REPORT: Regulating Human Cloning
(April 3, 2003)
The issue of human cloning has been the subject of much public
debate since the birth
of the cloned sheep Dolly was announced in 1997. The profound ethical questions
surrounding the prospect of the birth of a human clone have received much scrutiny.
In recent months, the debate has included the topic of human
stem cell research, which scientists believe could benefit from experimentation
using the procedure pioneered by the scientists who produced Dolly.
Nuclear Transplantation
This procedure is known as nuclear transplantation, or somatic
cell nuclear transfer. It involves removing the nucleus (which contains a cell's
DNA) from an egg cell, and transplanting the DNA from an adult cell into the
enucleated egg. Under certain conditions, the egg then begins to replicate as
though it were a fertilized embryo.
If this entity is implanted into a uterus, it has the potential
to develop into a full organism which would have the same DNA as the donor of
the adult cell. In other words, the organism would be a "clone." This
procedure is known as "reproductive cloning."
After the egg divides for several days, it produces embryonic
stem cells, which are primitive cells that can theoretically develop into virtually
any type of cells in the organism, from blood cells to skin cells. Scientists
believe that research on human stem cells could lead to new cures for many diseases.
The use of nuclear transplantation to produce human stem cells is often referred
to as "research cloning" or "therapeutic cloning."
The Link to Stem Cell Research
The issues of stem cell research and cloning are closely linked.
Researchers in the private sector have conducted experiments on human embryonic
stem cells after extracting them from excess embryos left over from fertility
treatments. They hope one day to use these cells for tissue transplants, and
one of the potential obstacles for such a procedure is rejection of the implanted
cells by the patient's immune system. Through nuclear transplantation, stem
cells could be created with the same genetic makeup as the patient, which some
scientists believe would reduce or eliminate the risk of immune rejection.
Legislative Debate
There is widespread opposition in the U.S. to the birth of a human
clone (reproductive cloning). While a few groups argue that cloning is a legitimate
form of reproduction, opposition to these arguments is nearly unanimous in the
U.S. Congress, due to both ethical and safety concerns.
In July 2001, the House of Representatives passed the Weldon-Stupak
bill, which criminalizes nuclear transplantation in humans, whether for
reproductive or research purposes. This bill was introduced in the Senate as
the Brownback-Landrieu
bill and has been endorsed
by President Bush.
This legislation, however, has raised the ire of many scientists,
who argue that it will unduly restrict scientific research. Many science groups
back the Specter-Feinstein
bill, which would prohibit reproductive cloning but allow nuclear transplantation
research to go forward. It would impose criminal penalties on anyone who attempts
to implant the product of nuclear transplantation into a woman's uterus.
(Click here
to view AAAS's position on human cloning.)
Arguments Against Nuclear Transplantation Research
Proponents of a ban on nuclear transplantation
such as the Brownback-Landrieu legislation raise two main arguments. Religious
conservatives argue that human embryos should be afforded a moral status similar
to human beings and should not be destroyed, even in the course of conducting
research. They also argue that permitting nuclear transplantation would open
the door to reproductive cloning, because a ban only on implantation would be
difficult to enforce. In this second argument, conservatives are joined by a
coalition of environmental, women's health, and bioethics groups who are not
unalterably opposed to nuclear transplantation, but believe that it should not
be permitted until strict regulations are in place.
Arguments For Nuclear Transplantation Research
Proponents of a ban on reproductive cloning
that would permit nuclear transplantation research, such as the Specter-Feinstein
bill, include a coalition of science organizations, patient groups, and the
biotechnology industry. These groups argue that the moral status of a human
embryo is less than that of a full human being, and must be weighed against
the potential cures that could be produced by research using nuclear transplantation.
They contend that a ban on implantation on the product of nuclear transplantation
would be no more difficult to enforce than a ban on nuclear transplantation
itself. They argue further that criminalizing scientific research, which has
been done only very rarely in the past, would set a bad precedent.
Updated January 2003
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