Dolly the Sheep

Dolly was born on July 5, 1996, at the Roslin Institute in Scotland, the work of scientists Ian Wilmut, Keith Campbell, and colleagues (with the biotech firm PPL Therapeutics). Using a technique called somatic cell nuclear transfer, they took the nucleus from an adult sheep's cell, placed it in an unfertilized egg, and coaxed it to grow — making Dolly the first mammal cloned from an adult somatic cell. It was that precise achievement, not merely 'the first clone,' that made her historic: she proved a fully grown, specialized cell could be reset to build a whole new animal.

Her existence was announced on February 22, 1997, and the reaction was enormous. She appeared in Time magazine and was named Science journal's Breakthrough of the Year, and the news set off a worldwide debate about the ethics of cloning — human cloning fears, government moratoriums, and late-night monologue jokes all at once. She was named after Dolly Parton: because she'd been cloned from a mammary-gland cell, Wilmut said, they couldn't think of a more fitting namesake.

Dolly lived about six years and was euthanized on February 14, 2003, after developing a progressive lung disease; scientists found no evidence her cloning was to blame. Her taxidermied body went on display at the National Museum of Scotland in Edinburgh, where she remains one of its best-known exhibits — the ordinary-looking sheep who briefly made the whole world argue about the future.