Information excerpted from:
How Cloning Works
How Human Cloning Will Work
by Craig Freudenrich, Ph.D.
by Kevin Bonsor and Cristen Conger
http://science.howstuffworks.com/life/genetic/cloning.htm
Animal cloning has been the subject of scientific experiments for years, but garnered little attention until
the birth of the first cloned mammal in 1996, a sheep named Dolly.
Stephen Ferry/Getty Images
Introduction to How Cloning Works
On Jan. 8, 2001, scientists at Advanced Cell Technology, Inc., announced the birth of the first clone of an
endangered animal, a baby bull gaur (a large wild ox from India and southeast Asia) named Noah.
Although Noah died of an infection unrelated to the procedure, the experiment demonstrated that it is
possible to save endangered species through cloning.
Cloning is the process of making a genetically identical organism through nonsexual means. It has been
used for many years to produce plants (even growing a plant from a cutting is a type of cloning).
Animal cloning has been the subject of scientific experiments for years, but garnered little attention until
the birth of the first cloned mammal in 1996, a sheep named Dolly. Since Dolly, several scientists have
cloned other animals, including cows and mice. The recent success in cloning animals has sparked fierce
debates among scientists, politicians and the general public about the use and morality of cloning plants,
animals and possibly humans.
Why Clone?
The main reason to clone plants or animals is to mass produce organisms with desired qualities, such as a
prize-winning orchid or a genetically engineered animal -- for instance, sheep have been engineered to
produce human insulin. If you had to rely on sexual reproduction (breeding) alone to mass produce these
animals, then you would run the risk of breeding out the desired traits because sexual reproduction
reshuffles the genetic deck of cards.
Other reasons for cloning might include replacing lost or deceased family pets and repopulating endangered
or even extinct species. Whatever the reasons, the new cloning technologies have sparked many ethical
debates among scientists, politicians and the general public. Several governments have considered or
enacted legislation to slow down, limit or ban cloning experiments outright. It is clear that cloning will be a
part of our lives in the future, but the course of this technology has yet to be determined
Introduction to How Human Cloning Will Work
On July 5, 1996, the most famous sheep in modern history was born. Ian Wilmut and a group of Scottish
scientists announced that they had successfully cloned a sheep named Dolly.
If you stood Dolly beside a "naturally" conceived sheep, you wouldn't notice any differences between the
two. In fact, to pinpoint the only major distinguishing factor between the two, you'd have to go back to the
time of conception because Dolly's embryo developed without the presence of sperm. Instead, Dolly began
as a cell from another sheep that was fused via electricity with a donor egg. Just one sheep -- no hankypanky involved.
While Dolly's birth marked an incredible scientific breakthrough, it also set off questions in the scientific
and global community about what -- or who -- might be next to be "duplicated." Cloning sheep and other
nonhuman animals seemed more ethically benign to some than potentially cloning people. In response to
such concerns in the United States, President Clinton signed a five-year moratorium on federal funding for
human cloning the same year of Dolly's arrival [source: Lamb].
Today, after more than a decade since Dolly, human cloning remains in its infancy. Although cloning
technology has improved, the process still has a slim success rate of 1 to 4 percent [source: Burton]. That
being said, science is headed in that direction -- pending governmental restraints.
Scientists have cloned a variety of animals, including mice, sheep, pigs, cows and dogs. In 2006, scientists
cloned the first primate embryos of a rhesus monkey. Then, in early 2008, the FDA officially deemed milk
and meat products from cloned animals and their offspring safe to eat.
Creating a Human Clone
In January 2001, a small consortium of scientists led by Panayiotis Zavos, a former University of Kentucky
professor, and Italian researcher Severino Antinori said that they planned to clone a human in two years
[source: Kirby]. At about the same time, news surfaced about an American couple who planned to pay
$500,000 to Las Vegas-based company Clonaid for a clone of their deceased infant daughter [source:
Clonaid]. Neither venture produced documented success.
Then, in 2004, South Korean scientist Hwang Woo-suk announced that he and his research team had
cloned 11 human embryos for the purpose of extracting stem cells. However, after reviewing his work, a
panel at Seoul National University concluded that his findings were false. There hasn't been any confirmed
human clone created to date. When discussing cloning in the sense of doing so to make a duplicate of an
organism, we refer to it as reproductive cloning.
If human reproductive cloning proceeds, the primary method scientists will likely use is somatic cell
nuclear transfer (SCNT), which is the same procedure that was used to create Dolly the sheep. Somatic
cell nuclear transfer begins when doctors take the egg from a female donor and remove its nucleus, creating
an enucleated egg. A cell, which contains DNA, is taken from the person who is being cloned. Then the
enucleated egg is fused together with the cloning subject's cell using electricity. This creates an embryo,
which is implanted into a surrogate mother through in vitro fertilization.
Cloning Uses
At the outset of the clone craze, some scientists and companies focused on exploiting the science-fiction
aspects of the technology. For instance, Zavos and Antinori, mentioned earlier, aimed to develop cloning to
aid infertile couples -- to the tune of approximately $50,000 for the service. The group said that the
procedure would involve injecting cells from an infertile male into an egg, which would be inserted into the
female's uterus. This child would look the same as his or her father. Then there's the possibility of bringing
deceased relatives back to life. A now-defunct company called Genetics Savings & Clone performed this
type of cloning for a woman's dead cat, Little Nicky, in 2004.
Therapeutic cloning holds the most promise of valuable medical advancement. Therapeutic cloning is the
process by which a person's DNA is used to grow an embryonic clone. However, instead of inserting this
embryo into a surrogate mother, its cells are used to grow stem cells. These stem cells could become the
basis for customized human repair kits. They can grow replacement organs, such as hearts, livers and skin.
They can also be used to grow neurons to cure those who suffer from Alzheimer's, Parkinson's or Rett
syndrome. And since the stem cells would come from embryo clones using your own cell's DNA, your
body would readily accept them.
Human Cloning Ethics
Surveys have shown that few Americans approve of cloning for reproductive purposes, although more are
open to therapeutic cloning [source: Burton]. The U.S. government has established strategic roadblocks
related to human cloning, although no federal ban exists. First, the government won't fund research focused
on human cloning for reproduction. Also, the FDA, which regulates public cloning research, requires
anyone in the United States attempting to clone humans to first get its permission. President George W.
Bush's appointed Council on Bioethics unanimously opposed cloning for reproductive purposes.
Certain countries abroad have stricter standards, and more than 50 have legally banned research efforts on
reproductive human cloning [source: Medical Devices & Surgical Technology]. In Japan, human cloning is
a crime punishable by up to 10 years in prison. England has allowed cloning human embryos for
therapeutic use only. Many individual states have also passed laws restricting cloning.
While legal restrictions are one deterrent to pursuing human cloning at this time, some scientists believe
today's technology just isn't ready to be tested on humans. Ian Wilmut, one of Dolly's co-creators, has even
said that human cloning projects would be irresponsible. Cloning technology is still in its early stages, and
nearly 98 percent of cloning efforts end in failure. The embryos are either not suitable for implanting into
the uterus, or die some time during gestation or shortly after birth.
Those clones that do survive suffer from genetic abnormalities. Clone cells may age more rapidly,
shortening their lifespan, similar to what happened with Dolly. Some clones have been born with defective
hearts, lung problems, diabetes, blood vessel complications and malfunctioning immune systems. One of
the more famous cases involved a cloned sheep that was born but suffered from chronic hyperventilation
caused by malformed arteries leading to the lungs.
Opponents of cloning point out that while we can euthanize defective clones of other animals, it's morally
problematic if this happens during the human cloning process. Advocates of cloning respond that it's now
easier to pick out defective embryos before they're implanted into the mother. In 2005, the United Nations
attempted to pass a global ban on human cloning, but was unsuccessful due to disagreements over whether
therapeutic cloning should be included. For now, human cloning remains in a stalemate from both a
scientific and public policy perspective -- the future of human cloning will likely depend on which side
gives in first.