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When a scientist whose goal is to turn animals into drug factories
announced on Saturday in Britain that his team had cloned a sheep, the
last practical barrier in reproductive technology was breached, experts
say, and with a speed that few if any scientists anticipated.
Now these experts say the public must come to grips with issues as grand
as the possibility of making carbon copies of humans and as mundane, but
important, as what will happen to the genetic diversity of livestock if
breeders start to clone animals.
For starters, quipped Dr. Ursula Goodenough, a cell biologist at
Washington University in St. Louis, with cloning, "there'd be no need
for men."
But on a more serious note, Dr. Stanley Hauerwas, a divinity professor
at Duke University, said that those who wanted to clone "are going to
sell it with wonderful benefits" for medicine and animal husbandry. But
he said he saw "a kind of drive behind this for us to be our own
creators."
Dr. Kevin FitzGerald, a Jesuit priest and a geneticist at Loyola
University in Maywood, Ill., cautioned that people might not understand
clones. While a clone would be an identical, but much younger, twin of
the adult, people are more than just the sum of their genes. A clone of
a human being, he said, would have a different environment than the
person whose DNA it carried and so would have to be a different person.
It would even have to have a different soul, he added.
The cloning was done by Dr. Ian Wilmut, a 52-year-old embryologist at
the Roslin Institute in Edinburgh. Wilmut announced on Saturday that he
had replaced the genetic material of a sheep's egg with the DNA from an
adult sheep and created a lamb that is a clone of the adult. He is
publishing his results in the British journal Nature on Thursday.
While other researchers had previously produced genetically identical
animals by dividing embryos soon after they had been formed by eggs and
sperm, Wilmut is believed to be the first to create a clone using DNA
from an adult animal. Until now, scientists believed that once adult
cells had differentiated -- to become skin or eye cells, for example --
their DNA would no longer be usable to form a complete organism.
Wilmut reported that as a source of genetic material, he had used udder,
or mammary, cells from a 6-year-old adult sheep. The cells were put into
tissue culture and manipulated to make their DNA become quiescent. Then
Wilmut removed the nucleus, containing the genes, from an egg cell taken
from another ewe. He fused that egg cell with one of the adult udder
cells.
When the two cells merged, the genetic material from the adult took up
residence in the egg and directed it to grow and divide. Wilmut
implanted the developing embryo in a third sheep, who gave birth to a
lamb that is a clone of the adult that provided its DNA. The lamb, named
Dolly, was born in July and seems normal and healthy, Wilmut said.
In an interview, Wilmut said he wanted to create new animals that could
be used for medical research, and he dismissed the notion of cloning
humans. "There is no reason in principle why you couldn't do it," he
said. But he added, "All of us would find that offensive."
Yet others said that might be too glib. "It is so typical for scientists
to say they are not thinking about the implications of their work," said
Dr. Lee Silver, a biology professor at Princeton University. Perhaps, he
added, "the only way they can validate what they are doing is to say
they are just doing it in sheep."
Few experts think that sheep or other farm animals would be the only
animals to be cloned. While cloning people is illegal in Britain and
several other countries, John Robertson, a law professor at the
University of Texas at Austin who studies reproductive rights and
bioethics, said there were no laws against it in the United States.
If such a law was passed, Silver said, doctors could set up clinics
elsewhere to offer cloning. "There's no way to stop it," Silver said. "Borders
don't matter."
Dr. Ronald Munson, an ethicist at the University of Missouri at St.
Louis, said the cloning itself was relatively simple. "This technology
is not, in principle, policeable," he said. "It doesn't require the sort
of vast machines that you need for atom-smashing. These are relatively
standard labs. That's the amazing thing about all this biotechnology.
It's fundamentally quite simple."
One immediate implication of cloning, Silver said, would be for genetic
engineering: custom-tailoring genes. Currently, scientists are unable to
take a gene and simply add it to cells. The process of adding genes is
so inefficient that researchers typically have to add genes to a million
cells to find one that takes them up and uses them properly. That makes
it very difficult to add genes to an embryo -- or a person -- to correct
a genetic disease or genetically enhance a person, Silver said. But now,
"it all becomes feasible," he said.
After adding genes to cells in the laboratory, scientists could fish out
the one cell in a million with the right changes and use it to clone an
animal -- or a person. "All of a sudden, genetic engineering is much,
much easier," Silver said.
Wilmut is hoping that the genes for pharmacologically useful proteins
could be added to sheep mammary cells and that the best cells could be
used for cloning. The adult cloned sheep would produce the proteins in
their milk, where they could be easily harvested.
Because cloning had been considered so far-fetched, scientists had
discouraged ethicists from dwelling on its implications, said Dr. Daniel
Callahan, a founder of the Hastings Center, one of the first ethics
centers.
In the early 1970s, "there was an enormous amount of discussion about
cloning," Callahan said, and ethicists mulled over the frightening
implications. But scientists dismissed these discussions as idle
speculation about impossible things, Callahan recalled, and urged
ethicists not to dwell on the topic.
"A lot of scientists got upset," Callahan said. "They said that this is
exactly the sort of thing that brings science into bad repute and you
people should stop talking about it."
In the meantime, however, cloning had captured the popular imagination.
In his 1970 book, "Future Shock," Alvin Toffler speculated that "cloning
would make it possible for people to see themselves anew, to fill the
world with twins of themselves."
Woody Allen's 1973 movie "Sleeper" involved a futuristic world whose
leader had left behind his nose for cloning purposes. Allen played a
character charged with cloning to bring the leader back. A later movie,
"The Boys From Brazil," released in 1978, involved a Nazi scheme to
clone multiple Hitlers. That same year, a science writer, David Rorvik,
published a book, "In His Image: The Cloning of a Man," that purported
to be the true story of a wealthy man who had secretly had himself
cloned but was found to be a hoax.
But gradually, the notion disappeared from sight, kept alive only in the
animal husbandry industry, where companies saw a huge market for cloned
animals and where the troubling ethical implications of cloning could be
swept aside.
Now these questions are back to haunt ethicists and theologians.
Clones of animals, FitzGerald said, might sound appealing -- scientists
could clone the buttery Kobe beef cattle or the meatiest pigs, for
example. But these cloned creatures would also share an identical
susceptibly to disease, he cautioned. An entire cloned herd could be
wiped out overnight if the right virus swept through it.
FitzGerald wondered if people would actually try to clone themselves. "Because
we have all this technology and we have this ability," he said, "we can
spin off these fantasies. But that doesn't mean we'd do it. It would be
going against everything we desire for the human race."
Others are less sure. Robertson can envision times when cloning might be
understandable. Take the case of a couple whose baby was dying and who
wanted, literally, to replace the child. Robertson does not think that
would be so reprehensible.
Cloning might also be attractive to infertile couples who want children
and who "want to be sure that whatever offspring they have has good
genes," Robertson said.
Of course, there are legal issues, Robertson said, like the issue of
consent. "Would the person being cloned have an intellectual property
right or basic human right to control their DNA?" he asked. If the
person did, and consented to the cloning, would cloning be procreation,
as it is now understood?
Robertson thinks not. After all, he said, "replication is not
procreation." |
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