Ian Wilmut, the British scientist who led the project that cloned a mammal for the first time, Dolly the sheep, shocking scientists who had thought that such a procedure was impossible, died on Sunday. He was 79.
The Roslin Institute, a research center near Edinburgh where Dr. Wilmut had worked for decades, said in a statement that the cause was complications of Parkinson’s disease. It did not say where he died.
Dr. Wilmut and his team were catapulted into headlines worldwide in February 1997, when they announced their ovine subject’s remarkable birth in the journal Nature.
Cloning from embryonic cells was already known to work; in 1995, Dr. Wilmut and his research partner, Keith Campbell, had swapped out the nuclei of two sheep embryos with those of two others, producing two identical ewes, Megan and Morag. (Dr. Campbell died in 2012.) But most scientists had thought it would be impossible to clone an animal using adult cells.
The problem, they said, was that an embryonic cell would accept only a nucleus from another embryo. It was Dr. Campbell who devised a solution: By taking a differentiated cell and starving it, he could essentially put it into hibernation, a state that would trick a receiving embryo into accepting it.
The work was rough going. Out of some 300 attempts, only one embryo proved viable. Dolly, named for the singer Dolly Parton, was born in July 1996. Dr. Wilmut decided to keep the news secret until he and Dr. Campbell were sure that she would survive infancy.
The announcement of Dolly’s birth was among the biggest news events of 1997, alongside the handover of Hong Kong from the British to China and the death of Diana, Princess of Wales. It was met with a mixture of awe and anxiety, with politicians and medical ethicists calling for an immediate ban on human cloning.
Dr. Wilmut agreed. In the spring of 1997, he toured the United States, meeting with scientists, speaking to standing-room-only crowds and testifying before Congress.
His message was consistent: Human cloning should never, ever be permitted. He called the very prospect of it “offensive,” because of both the risk of birth defects and the fact that a clone would never be accepted as a full human being.
“Human cloning has grabbed people’s imagination, but that is merely a diversion and one we personally regret and find distasteful,” Dr. Wilmut wrote in “The Second Creation: Dolly and the Age of Biological Control,” which he published in 2000 with Dr. Campbell and Colin Tudge.
Dolly’s life seemed to play out some of the risks. Though she was able to bear lambs, she developed early-onset arthritis and exhibited other traits more commonly associated with older animals. After she developed a viral lung infection in 2003, veterinarians euthanized her.
Her stuffed body was put on display at the National Museum of Scotland later that year.
“She’s been a friendly face of science,” Dr. Wilmut said in an interview with The New York Times after Dolly’s death. “She was a very friendly animal that was part of a big scientific breakthrough.”
Ian Wilmut was born on July 7, 1944, in Hampton Lucy, a village near Stratford-upon-Avon, England. His parents, Leonard (also known as Jack) and Eileen (Dalgleish) Wilmut, were teachers.
He entered the University of Nottingham intending to become a farmer, but gave up after he realized that he was, he later said, “helpless on tractors.” A summer internship in an animal-science lab at Cambridge University persuaded him to try academic research instead.
After graduating with a degree in animal science in 1967, he went directly to Cambridge, where he received a doctorate in embryology in 1971; his dissertation was on freezing boar semen. He continued that work at the Animal Breeding Research Station, outside Edinburgh. (The facility became the Roslin Institute in 1993.)
In 1973, Dr. Wilmut and a team of scientists became the first to breed a calf from a frozen embryo, an achievement that revolutionized animal husbandry.
By the 1980s he had become more interested in the medical, rather than the commercial, applications of his work. His father had lived with diabetes, which left him blind for the last 30 years of his life, a family tragedy that drove Dr. Wilmut forward.
He and Dr. Campbell chose to work on sheep, they said, because in Scotland the animals are everywhere, and they are cheap. Their original goal was to create milk containing proteins used to treat human diseases and to make stem cells that could be used in regenerative medicine.
After the clamor around Dolly’s birth died down, Dr. Wilmut continued to research cloning. Despite his early opposition to working with human cells, in 2005 he received a license from the British government to clone human embryos in order to produce stem cells, with the understanding that the embryos would be destroyed before becoming viable.
But he soon gave up that work after a team of scientists in Japan found a way to develop stem cells without the use of embryos, a much more efficient process — and one that relied directly on his own work.
Dr. Wilmut received a knighthood in 2008, an honor that was met with some protest by medical ethicists, who contended that his achievement was morally fraught, and by former colleagues who believed that other people, including Dr. Campbell, deserved more of the credit. He moved to the University of Edinburgh in 2005 and retired in 2012.
Dr. Wilmut married Vivienne Craven in 1967. She died in 2015. He is survived by his second wife, Sara; his son, Dean; his daughters, Naomi Wilmut and Helen Wilmut; and five grandchildren.
Dr. Wilmut revealed that he had Parkinson’s disease in 2018. It was incidentally one of the conditions that he had envisioned his work addressing. He also said he would participate in a research program to test new types of treatments intended to slow the disease, which affects the part of the brain that controls movement.
“It was from such a rich seedbed that Dolly developed,” he told The Times in 2018, “and we can hope for similar benefits in this project.”