Keith Campbell, a British cell biologist who helped usher into being one of the most famous animals in creation, Dolly the cloned sheep, died last Friday at his home in the Derbyshire region of England. He was 58.
His death was announced by the University of Nottingham, where he had taught since 1999. The cause was not made public.
In February 1997, Dr. Campbell and his colleague Ian Wilmut, both then on the staff of the Roslin Institute, a research center near Edinburgh, disclosed that Dolly, the first mammal to be cloned from an adult animal, had been born in Scotland the summer before.
The announcement, which seized the attention of the world news media, was divisive. On the one hand, the experiment engendered great excitement for defying conventional scientific belief: cloning a living being from an adult cell had long been deemed impossible.
On the other, it gave rise to abundant agonizing, as pundits and public alike worried that the cloning of human beings à la "The Boys From Brazil" -- Ira Levin's 1976 novel and the subsequent film about the cloning of a welter of Hitlers -- was not far behind.
After Dolly's creation, human reproductive cloning was banned in several countries, including Canada and Australia, and in about a dozen American states. In 2005, the United Nations adopted a nonbinding declaration calling for its members to ban human cloning in all its forms.
Dr. Campbell, who said he was a fan of the film "The Boys From Brazil," was quick to say that human cloning was a distant dream, and that he deplored the idea in any case.
The real value of cloning, he said, lay in the potential to engineer animals to produce medications, and even transplantable organs, for use by human beings. Those prospects, too, have so far remained largely unrealized.
Although Dr. Wilmut was credited as the lead scientist on the research that produced Dolly, he later said that Dr. Campbell deserved "66 percent" of the credit for the work. The order of the names on their published research announcing Dolly's creation, Dr. Wilmut said, had been determined by both men by prearrangement.
It had been, in fact, a watershed idea of Dr. Campbell's that made Dolly possible at all.
Keith Campbell was born in Birmingham, England, on May 23, 1954. Interested from a very early age in what made animals tick, he was the kind of boy who, as the newspaper Scotland on Sunday reported in a 2000 article, "used to fill his mother's kitchen with frogs."
He earned a bachelor's degree in microbiology from the University of London in 1978, followed in 1986 by a doctorate from the University of Sussex. He joined the staff of the Roslin Institute in 1991.
At the time, cloning much of anything from the cells of a mature creature was considered a pipe dream. Adult cells are programmed to produce one thing, and one thing only: skin cells make skin, bone cells make bone, and so on.
To clone an entire organism, scientists believed, one had to start with embryonic cells, which had not yet undertaken their specialized roles.
In 1995, using embryonic cells, Dr. Campbell and Dr. Wilmut created a pair of cloned lambs, Megan and Morag. Of the mammals considered likely candidates for the procedure, sheep were chosen, Dr. Campbell later said, because "sheep in Scotland are very, very, very cheap."
The two men next turned their attention to cloning a cell from an adult sheep. Here, Dr. Campbell had a crucial insight: Perhaps, he speculated, it was possible to turn back the clock on the specialized adult cells -- to return them to the state they were in before their functions diverged.
If that were the case, a single cell from any part of a mature animal might then be coaxed into producing the entire creature.
By "starving" mature cells of nutrients in the laboratory, Dr. Campbell found, he was able to do just this, causing them to regress to their undifferentiated states.
In January 1996, he and his colleagues took cells from the udder of a 6-year-old sheep, starved them and introduced them into eggs donated by other sheep. Of the nearly 300 eggs they fused in this way, only a handful developed fully enough to be implanted in the wombs of adult ewes.
Of these, only one resulted in a live birth: Dolly, born on July 5, 1996. Because she owed her very existence to mammary cells, she was named for Dolly Parton, the pneumatic country singer.
In 1997, Dr. Campbell became head of embryology at PPL Therapeutics, a biopharmaceutical company with offices in Scotland. That year, he and Dr. Wilmut created Polly, a lamb cloned from the skin cells of fetal sheep, who also had a copy of a human gene added to every cell. Such work was a first step in producing animals whose milk or organs might one day have therapeutic use for humans.
Dr. Campbell's survivors include two daughters, Claire and Lauren.
Dolly, who suffered from arthritis and lung ailments, was euthanized in 2003; her stuffed remains are on display at the National Museum of Scotland in Edinburgh. In 2007, Dr. Campbell cloned four new lambs from the original genetic material that had produced Dolly.
During her life, Dolly was also bred the traditional way and gave birth to six lambs.
"It will always be the preferred way of having children," Dr. Campbell told The New York Times in 1997. "Why would anyone want to clone, anyway? It's far too expensive and a lot less fun than the original method."
This article originally appeared in The New York Times.