Dolly the Sheep Cloned
Scientists at the Roslin Institute announced the first successful cloning of a mammal
February 22, 1997
The World Meets Dolly
On July 5, 1996, a lamb was born at the Roslin Institute near Edinburgh, Scotland. She looked like any other sheep, but Dolly was unlike any animal that had ever lived. She was the first mammal successfully cloned from an adult cell. Scientists led by Ian Wilmut and Keith Campbell took a cell from the mammary gland of a six-year-old Finn Dorset sheep and used its DNA to create a new embryo. That embryo was implanted into a surrogate mother and grew into Dolly. Her birth was announced to the public in February 1997 and triggered a worldwide debate about the future of science.
How Cloning Works
The technique used to create Dolly is called somatic cell nuclear transfer, or SCNT. Scientists remove the nucleus from an egg cell and replace it with the nucleus from an adult body cell. The egg is then stimulated to start dividing as if it had been fertilized. The resulting embryo is genetically identical to the animal that donated the adult cell. Before Dolly, scientists believed that once a cell became specialized, it could not be used to create a whole new organism. Dolly proved that belief wrong and opened entirely new possibilities in biology and medicine.
Dolly's Life and Lasting Impact
Dolly lived at the Roslin Institute and became one of the most famous animals in history. She had six lambs of her own through natural reproduction. In 2003, Dolly was euthanized after developing a progressive lung disease. Scientists noted that she also showed signs of premature aging, sparking questions about whether cloned animals age faster than normal. Her death did not end the research she inspired. Since Dolly, scientists have cloned dozens of other mammals, including cats, dogs, horses, and cattle. The technology has been used in conservation efforts and biomedical research, though human reproductive cloning remains widely banned.