Dollymania: How Dolly the Sheep Became a Media Sensation in the '90s

On Saturday, February 22, 1997, British scientists Ian Wilmut and Keith Campbell prepared for a quiet moment before the groundbreaking results of their revolutionary experiment were revealed to the world.

For seven months, the team had kept their breakthrough a secret, awaiting the publication of their paper in the renowned journal Nature. Confidential press releases were sent to journalists with strict instructions to keep the news under wraps until February 27.

However, that night, the team learned that journalist Robin McKie was planning to publish the story the very next day in the British newspaper The Observer.

On Sunday morning, Wilmut and Campbell hurried to the Roslin Institute as McKie’s story exploded across the media. News outlets from around the world began flooding the institute to catch a glimpse of Wilmut and Campbell’s groundbreaking creation: Dolly the sheep, the first mammal ever cloned from a single adult cell. Hidden from the public eye, Dolly poked her nose through the fence, calmly munching on hay, seemingly oblivious to the swarm of journalists capturing every moment. A woolly, bleating scientific marvel, Dolly resembled other sheep, but with a significant genetic distinction.

By the end of Sunday, February 23, headlines about Dolly the sheep had appeared in nearly every major newspaper globally.

A Long-Awaited Scientific Milestone

Dolly was born on July 5, 1996, at the Roslin Institute, part of the University of Edinburgh, in collaboration with Scottish biotech company PPL Therapeutics. Her cloning involved taking DNA from a single sheep mammary gland cell, inserting it into an egg from another sheep, and then implanting the embryo into a surrogate mother sheep. In essence, Dolly had three mothers: one provided the DNA, another the egg, and the third carried the embryo to term. Despite this, Dolly was genetically identical only to the sheep from which the original cell was taken.

Following the announcement, the Roslin Institute was inundated with 3,000 phone calls from across the globe. Dolly's birth was hailed as one of the most significant scientific breakthroughs of the decade.

However, Dolly was not the first foray into cloning. Scientists had been probing the complexities of cloning for nearly a century. In 1902, German embryologists Hans Spemann and Hilda Mangold, his student, successfully grew two salamanders from a single embryo that was split using a noose made of a strand of hair. Over time, cloning experiments advanced and became increasingly refined. Several animals, including frogs and cows, had been cloned from embryos before Dolly. But Dolly made history as the first mammal cloned from a specialized adult cell.

Embryonic stem cells, which form immediately after fertilization, are capable of developing into any type of cell in the body. Once these cells evolve into specific types, such as neurons or blood cells, they are called specialized cells. Since the cell that gave rise to Dolly had already specialized as a mammary gland cell, most scientists believed it would be impossible to clone anything but other mammary gland cells. Dolly disproved that assumption.

A Global Reaction—And Debate

In the 1990s, many scientists were astonished. Dolly’s creation demonstrated that specialized cells could be used to produce a perfect clone of the animal from which they originated. “It means all science fiction is true,” Princeton University biology professor Lee Silver told The New York Times in 1997.

The Washington Post reported that “Dolly, depending on the commentator, is considered the biggest story of the year, the decade, or even the century. Wilmut has found himself compared to figures like Galileo, Copernicus, Einstein, and at least once, even Dr. Frankenstein.”

Scientists, lawmakers, and the public quickly envisioned a future shaped by the dangers of unethical human cloning. President Bill Clinton called for a review of the bioethics of cloning and introduced legislation to ban cloning intended “for the purposes of creating a child” (the bill was not passed). The World Health Organization determined that human cloning was “ethically unacceptable and contrary to human integrity and morality” [PDF]. A Vatican newspaper editorial called on governments to outlaw human cloning, arguing that every human has “the right to be born in a human way and not in a laboratory.”

However, some scientists remained skeptical about the validity of Wilmut and Campbell’s experiment. Norton Zinder, a molecular genetics professor at Rockefeller University, criticized the study published in Nature as “a bad paper,” arguing that Dolly’s genetic lineage could not be confirmed without testing her mitochondria—the DNA passed down through mothers. This test would have proven whether Dolly was truly the offspring of the sheep that birthed her. In an interview with The New York Times, Zinder referred to the Scottish duo’s work as “just lousy science, incomplete science.” Despite this, NIH director Harold Varmus told The Times that he was confident Dolly was indeed a clone of an adult sheep.

Dollymania!

Since she was cloned from a mammary gland cell, Dolly earned her name—get ready for a dad joke—after the well-endowed country music legend Dolly Parton. (Parton took the comparison in stride.) Like her famous namesake, Dolly the sheep became a true celebrity: She graced the covers of magazines like People; inspired books, articles, and essays; even had an opera composed in her honor; appeared in commercials; and was used as a symbol during an election campaign.

That wasn't the end of it: New York Times journalist Gina Kolata, one of the first to offer an in-depth look at Dolly, wrote Clone: The Road to Dolly, and the Path Ahead, drawing comparisons between the sheep's creation and classic characters like those in Frankenstein and The Island of Dr. Moreau. American composer Steve Reich was so moved by Dolly’s story that he incorporated it into Three Tales, a video-opera exploring the perils of technology.

The sheep also unexpectedly became a political symbol when the Scottish National Party used her image on campaign posters, suggesting that rival political candidates were mere clones of each other. The appliance company Zanussi took advantage of her likeness in a poster featuring her name and the provocative slogan “The Misappliance of Science” (the advertisement was later retracted after backlash from the scientific community). Dolly's name became so commercially exploited that her creators eventually trademarked it to prevent further misuse.

Dolly’s Lasting Impact

After Dolly, cloning was extended to larger mammals, including horses and bulls. Roslin Biomed, a company established by the Roslin Institute to focus on cloning research, was eventually acquired by U.S.-based Geron Corporation, which integrated cloning with stem cell research. However, despite Dolly’s fame—and the widespread concern surrounding it—her birth did not spark a boom in cloning. Human cloning was considered too dangerous and unethical, while animal cloning proved minimally beneficial for agriculture. Dolly’s true legacy is regarded as a significant advancement in stem cell research.

Dolly’s creation proved it was possible to alter a cell’s gene expression by replacing its nucleus with one from another cell. Stem cell researcher Shinya Yamanaka shared with Scientific American how Dolly’s cloning inspired him to successfully generate stem cells from adult cells. This achievement later earned him a Nobel Prize for his development of induced pluripotent stem cells (iPS), which are artificially created and versatile. These iPS cells have greatly diminished the reliance on embryonic stem cells in research, and are now fundamental to most stem cell-based therapies, including regenerative medicine.

Dolly had six offspring, and led a vibrant, sociable life, with many visitors coming to see her. In 2003, a veterinary checkup revealed that Dolly had a progressive lung disease, which led to her being euthanized. However, four clones derived from the same cell line in 2007 exhibited no similar health issues and aged as normal.

Dolly continues to captivate people, even nearly 25 years after her birth: Her preserved body is displayed at the National Museum of Scotland in Edinburgh.

A version of this article was originally published in 2020 and has been updated for 2023.