Multiplicity: Scientists clone a sheep named Dolly
NewsHour coverage of: Science
A QUESTION OF
Myself and I
The idea of cloning living beings was probably hatched in the mind of a science fiction writer. But the concept took a giant step toward becoming reality in 1997, when scientists in Scotland cloned the first mammal: a sheep named Dolly.
Cloned cows, goats, pigs and mice soon followed. Now, a team of researchers is planning to clone another type of mammal - humans. Researchers haven't quite worked out all the bugs in the system, but they say they'll have a clone human in about two years.
1+1 = 2 is yesterday's math -- at least when it comes to cloning. Now it's all about making babies from just one parent.
Cloning essentially starts with the genetic material (DNA) from an adult human. This DNA can come from almost any cell -- a blood cell, for example, or a skin cell. That DNA blueprint, or instructions, is implanted into a human egg that has been "stripped" of its own DNA.
If all goes well, the egg cell develops into an embryo, which is implanted in the uterus of a surrogate female. From then on, the process is pretty familiar. The fetus grows for nine months and is born the old-fashioned way. But instead of having a mix of genes from two parents, the baby has an exact copy of the genes from one parent (either male or female) -- and no genetic input from the woman who gave birth to it. The result is a genetic twin of the DNA donor.
Your double, but not really
So, even if you cloned yourself, the clone would still be born a baby. (So forget the idea of sending your clone to school, while you played in the park or have your clone do your chores while you talked on the phone.)
The cloned baby would grow up to look just like its genetic parent, but wouldn't necessarily have the exact same personality. That's because personality is heavily influenced by life experience and environment. As the cloned baby grows up, it will have its own memories, dreams and thoughts.
The clone would,
in most legal cases, have the same rights as a baby made the old-fashioned
way. It would not 'belong' to the genetic parent; most governments don't
allow people to own people. So, while you're spending your teen years
listening to Limp Bizkit and Eminem, your clone could grow up to be
the biggest fan ever of a future boy band.
Should we go there?
Some people have serious doubts about whether cloning humans is a good idea. It raises a ton of legal, moral and ethical questions. And even if those are worked out, some people have religious objections to what they call "playing God." Other people just think cloning sounds kind of spooky, and is not something humans should mess around with.
Some people fear that clones could give rise to a race of superhumans - a world of cloned superstars, athletes, Nobel Prize winners and beautiful people. Just because we can do it, they say, doesn't mean we should.
But researchers say the scientific knowledge necessary to clone a human is out there, and cannot be stopped. Human cloning will happen sooner or later.
Many doctors say the knowledge gained from successful cloning will help them fight diseases and discover new medicines. One of the biggest benefits is research on "stem cells" -- special cells in embryos that can be used to "grow" new organs and nerve tissue.
Cloning could also
help infertile people have children.
Most cloned animals are also infertile and cannot reproduce sexually. Some doctors say cloning humans would likewise result in massive numbers of miscarriages and birth defects.
Critics say it would be immoral to give birth to cloned babies, knowing the high potential for birth defects. Besides, doctors say, there is also a health risk to women carrying clones. Most cloned animals are born very large and all bear the telltale sign of cloning - unusually large navels, because inexplicably, umbilical cords grow oversized in cloned pregnancies.
A final concern is that cloning could reduce the variety of the human gene pool.
The current team of scientists, led by researchers from the U.S., Italy, and Israel, is now looking for a host country where the government will allow them to perform their research. Israel and Italy are considering the idea.
But in the U.S., congress is also considering a law that would make cloning humans illegal. California, Michigan, Louisiana and Rhode Island have made it illegal. Britain has approved some forms of human cloning, while Japan has outlawed the practice.
The court of public opinion
"When you see something that is technically sweet, you go ahead and do it and you argue about what to do about it only after you have had your technical success," said J. Robert Oppenheimer, one of the creators of the atom bomb.
Many people view cloning the same way Oppenheimer viewed atomic energy-- an incredibly powerful technology that can be used for good or evil, but once unleashed, can't be put back in the box.
Scientist William Joy has been a leading voice urging caution on new technologies like cloning.
"The technologies that are emerging in the 21st century genetic engineering, nanotech, and robotics-- have enormous potential, but they carry a hidden danger, along with this enormous potential, of a kind that I don't think we've ever faced before," he said last year on the NewsHour.
The Last Horizon?
Ultimately, most scientists say cloning humans should not occur until more facts about the process are known. One fear is that cloned babies would look much older than they are (a problem that happened to Dolly the sheep) because parts of their DNA are match the age of the genetic parent. A 5-year old might look like a 10-year old, with potential for illnesses to develop.
Also, human cloning requires the use of adult somatic cells. Because somatic cells are used rather than reproductive cells, genetic "imprinting," the molecular mechanism which genes inside sperm and egg cells are turned "on" or "off" in preparation to develop an embryo, doesn't happen. Although the fluids in the egg cell can reset the genes in the adult cell to the "on" position, the process is hardly perfect and abnormalities usually occur.
But advances in science keep making the impossible, possible. Moral and ethical concerns are often eased over time with public understanding.
Less than 20 years ago, the idea of creating "test-tube babies" scared a lot of people. Today, it's known as in-vitro fertilization, a common and accepted method for couples who haven't been able to have a baby naturally.
Who knows, the issue of cloning humans could just be in the timing?
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