Two monkeys have followed in the footsteps of Dolly the Sheep by becoming the world’s first primates to be cloned from transferred DNA.
Identical long-tailed macaques Zhong Zhong and Hua Hua were born eight and six weeks ago respectively at a laboratory in China.
The success marks a watershed in cloning research and raises major ethical questions.
The scientists hope to pave the way for populations of genetically uniform monkeys that can be customised for ground-breaking research into human diseases.
But the cloning of monkeys will be seen by some as a step toward the creation of human clones.
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Zhong Zhong and Hua Hua are not the first primate cloned. Tetra, a rhesus monkey, was born in 1999 through a simpler method called embryo splitting.
They are, however, the first primates to be cloned using something known as the same single cell nuclear transfer (SCNT) technique.
This was the same technique used on Dolly, who made history 20 years ago after being cloned at the Roslin Institute in Edinburgh.
It was the first time scientists had managed to clone a mammal from an adult cell, taken from the udder of a Finn Dorset sheep.
Since then many other mammals have been cloned using the same single cell nuclear transfer (SCNT) technique, which involves transferring cell nucleus DNA to a donated egg cell that is then prompted to develop into an embryo.