“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.
爱丁堡大学生殖生物学家伊恩·维尔莫特称：“越来越多的物种被成功克隆使人们确信： 所有哺乳动物， 包括人类本身， 都是可能被克隆的。” 维尔莫特是第一个克隆哺乳动物的科学家， 大约 10 年前他成功利用成体细胞克隆了绵羊多莉。 此后研究人员相继克隆了猫、 山羊、 牛、 老鼠、 猪、 免予、 马、 鹿、 骡及白肢野牛(东南亚地区一种大野牛)。 但迄今为止， 用同样方法克隆猴子或其他灵长类动物的尝试均告失败。 克隆动物的健康状况及寿命也仍然存在不确定性： 绵羊多莉 2003 年就因患癌症及关节炎夭亡。