South Koreas stem cell scientists have cloned a dog, smashing another biological barrier and reigniting a fierce ethical debate—while producing a perky, lovable puppy. This immediately renewed calls for a global ban on human reproductive cloning before the technology moves any farther. "Successful cloning of an increasing number of species confirms the general impression that it would be possible to clone any mammalian species, including humans," said Ian Wilmut, a reproductive biologist at the University of Edinburgh who produced the first cloned mammal, Dolly the sheep, from an adult cell nearly a decade ago. Researchers have since cloned cats, goats, cows, mice, pigs, rabbits, horses, deer, mules and gaur, a large wild ox of Southeast Asia. So far, efforts to clone a monkey or another primate with the same techniques have failed. Uncertainties about the health and life span of cloned animals persist; Dolly died prematurely in 2003 after developing cancer and arthritis.
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