Cloning is now one of the emerging technologies, initiated when Dolly the sheep was cloned two decades ago. Chinese scientists have now cloned two healthy female monkeys for the first time leading us a step closer to human cloning.

Zhong Zhong and Hua Hua were cloned from a non-embryonic cell. Born eight and six weeks ago respectively, these two long-tailed macaques are the first primates ever to be cloned by the similar technique ‘somatic cell nuclear transfer (SCNT)’ through which Dolly the sheep was cloned.

Since Dolly the sheep, many mammals have been cloned, including cats, dogs, rats, cattle, cows, pigs, and rabbits. The cloning of primates, however, has been the first, said the study published in Cell.

Through SCNT, the nucleus is replaced in the donor egg with a nucleus taken from a cell from another animal. Electric current was passed to fertilize the egg and after fertilization, the egg develops into an embryo that can be rooted into a surrogate for gestation. The result is the genetic copy of whatever animal donated the nucleus, reported Futurism.

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However, the process was not just successful in first try. Seventy nine embryos were implanted into 21 surrogates, of which six of them became pregnant and two gave successful births of Zhong Zhong and Hua Hua.

Researchers believe that this makes them closer to replicate humans too because of the genetic similarities. “Humans are primates. So [for] the cloning of primate species, including humans, the technical barrier is now broken,” said supervisor Mu-Ming Poo.

However, according to Business Insider, a cloning expert, Robin Lovell-Badge who wasn’t involved in the study expressed, “It remains a very inefficient and hazardous procedure. The work in this paper is not a stepping-stone to establishing methods for obtaining live born human clones. This clearly remains a very foolish thing to attempt.”