Dolly the sheep made history in 1997, when the scientists who created her announced she was the first cloned mammal to survive.For a while, she was a media star with a profile almost approaching that of her namesake Dolly Parton. At the peak of her fame, she even made the cover of Time Magazine.But her spotlight faded fast. And at the age of just six years old, she died, euthanized after fighting a lung disease. The science journal Nature designed a special issue around her obituary, even though the average person had already forgotten her.Although Dolly's life was short, it wasn't your average sheep's life. And where she is now is even more surprising.Scientists created Dolly in a test tube, after they figured out how to take a sheep egg cell, remove its DNA, and replace it with DNA extracted from a different sheep's skin cell. The newly fused cell was then implanted into a surrogate mother sheep, who gave birth to Dolly on July 5, 1996.Dolly was the only lamb to be born out of 30 embryos implanted into surrogate sheep and another 250 embryos that never got far enough to be implanted.All that happened at the Roslin Institute, part of the University of Edinburgh in Scotland, which is still developing the science of cloning mammals. Dolly's existence was kept secret for more than six months to make sure she wouldn't be joining the long chain of failed attempts to clone mammals.Dolly lived at Roslin for the rest of her life. Her keepers wanted to give her a normal sheep's life, so they mated her with a small Welsh mountain ram. Dolly had six lambs this way.At the same time, scientists cloned Dolly herself, creating 10 sheep that were born in 2007.Four of these sheep, nicknamed the "Nottingham Dollies," are still alive and thriving at the age of nine. (The breed Dolly and her clones belong to, Finn Dorsets, are known to live as long as 12 years.)That's in stark contrast to Dolly herself.She was allegedly overfed when she was young in a quest to get better photos and videos of her, which led to lifelong weight problems.When she was a year old, scientists investigating her genes found the telomeres at the ends of her DNAmicroscopic structures that are associated with lifespanwere shorter than usual. So the world worried that cloning led to bad health. (Another early controversy questioned whether she was truly a clone, but further testing reaffirmed her claim.)Those fears seemed to come true when Dolly began showing signs of arthritis in 2001, when she was 5 years old. This was followed in 2003 by a case of sheep pulmonary adenomatosis, a viral disease that makes invincible tumors grow in the lungs, which a few other sheep at the facility had also caught. Scientists decided to euthanize Dolly when they reached this diagnosis.Her remains are now on display at the National Museums of Scotland, stuffed with her head crooked inquisitively, perched on a thin layer of straw.After her death, Dolly was also the subject of a long and bitter court case over whether she and other animals produced by the same cloning method could be patented. The question was finally resolved in 2014: The cloning technique, called somatic cell nuclear transfer, remained patented, but Dolly herself was not.That decision joins a handful of cases shaping the plausibility and profitability of personalized medicine.Join the conversation about this storyNOW WATCH: Cloning your dog is easier than you think ' here's how it works
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