Dolly the Sheep Born: First Mammal Cloned from Adult

Scientists at Scotland s Roslin Institute took a single mammary gland cell from a six-year-old Finn Dorset sheep and used it to create a genetically identical lamb. Dolly, born on July 5, 1996, was the first mammal ever cloned from an adult somatic cell, proving that specialized cells could be reprogrammed to create an entirely new organism. The achievement overturned a fundamental assumption of developmental biology and ignited a global debate about the ethics of cloning that has never fully subsided. Ian Wilmut and Keith Campbell led the team that developed the technique, called somatic cell nuclear transfer. They removed the nucleus from an egg cell of a Scottish Blackface sheep and replaced it with the nucleus from the mammary cell of the Finn Dorset donor. An electrical pulse fused the two and triggered cell division. The resulting embryo was implanted in a surrogate mother. Out of 277 attempts, Dolly was the only lamb born alive. The announcement, published in Nature in February 1997, landed on front pages worldwide. The immediate public reaction focused on the possibility of human cloning, prompting President Clinton to request a report from the National Bioethics Advisory Commission within 90 days. Legislation banning human reproductive cloning was introduced in multiple countries. The Vatican condemned the research. Scientists rushed to replicate the result in other species. Dolly lived at the Roslin Institute for six years, producing six lambs through normal reproduction. She developed arthritis at an unusually young age and was diagnosed with a progressive lung disease common in older sheep. Researchers debated whether her health problems were related to the cloning process or simply bad luck. She was euthanized on February 14, 2003, at age six — roughly half the normal lifespan of a Finn Dorset sheep. The technique that created Dolly opened the door to therapeutic cloning, where patient-specific stem cells could theoretically be produced for medical treatment without immune rejection. Dolly s taxidermied body is displayed at the National Museum of Scotland in Edinburgh.