As the most advanced human embryo clones yet are produced, BBC News Online looks back as some of the landmark moments since 1997, when British scientists unveiled the first successful mammal clone.
1997: Dolly the sheep and the big breakthrough - the first successful mammal clone from an
ordinary adult cell.
1997 to 2000: Scientists at various institutes cloned various species
of animal - as other scientists claimed to be working towards the first human
1998: American Dr Richard Seed said he was ready to begin experiments on
cloning a human being within the next three months.
January 2001: Controversial Italian doctor Severino Antinori announced
plans to clone human babies for infertile couples at his fertility clinic in
April 2001: Dr Antinori reportedly said that a woman he was treating was
pregnant with a cloned embryo. It was later denied.
July 2002: Authorities in South Korea investigated a company's claim that
it had implanted a cloned human embryo in a South Korean woman.
November 2002: Dr Antinori announced that the first human baby clone
would be born in January 2003.
December 2002: Clonaid, founded by the Raelian sect, claimed the first
human clone was born, sparking surprise and condemnation. It has never provided
DNA proof of its cloning claims.
February 2003: Dolly the sheep is put down after a veterinary examination showed she had a progressive lung disease.
July 2003: The first UK research licence of its kind permitting a technique
that creates embryonic stem cells from human eggs was granted to the scientists
who cloned Dolly the sheep in Edinburgh. This is therapeutic, not reproductive, cloning.
September 2003: Dr Panos Zavos claims to have created the world's first
cloned human embryo.
He announced plans to implant the human embryo in a surrogate mother later in
October 2003: Scientists in China claimed they had created twins which
effectively had two "genetic mothers" and one father, but the experiment did
not create any live babies.
One expert called the experiment "proof of principle" for human cloning, but
others disagreed. The work was not aimed at producing genetic copies of humans.
January 2004: Dr Zavos announces a 35-year-old woman is hoping to give
birth to the world's first cloned baby.
February 2004: South Korean scientists clone 30 human embryos and develop them over several days to a stage where special cells known as embryonic stem cells could be extracted. The researchers hope to obtain cells that could one day be used to treat disease.
THE HUMAN CLONING DEBATE
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