When Was the First Cloned Mammal Born?

Dolly was produced through somatic cell nuclear transfer (SCNT): the nucleus of an adult mammary gland cell from a six-year-old Finn Dorset ewe was transferred into an enucleated egg cell from a Scottish Blackface ewe, stimulated to divide, and implanted into a surrogate mother. Out of 277 attempts, Dolly was the only lamb born alive. Her birth, announced in February 1997, was a scientific sensation and sparked worldwide debates about cloning ethics, including the potential for human cloning. Dolly lived a relatively normal life, producing six lambs naturally, but developed premature arthritis and a progressive lung disease. She was euthanised on 14 February 2003 at age six (sheep normally live 10-12 years). Since Dolly, dozens of species have been cloned, including cats, dogs, horses, and endangered animals.