Cloning advances: From sheep and dogs to… woolly mammoths and humans?

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Twenty years after Dolly the Sheep was successfully cloned, NBC’s Keir Simmons gains exclusive access to a cloning factory to South Korea to investigate the latest developments, including efforts to clone extinct woolly mammoths, using Asian elephants as surrogate mothers. But he reports human cloning would be extremely difficult – not to mention already illegal in some countries.