Where Are All the Clones?

It’s 20 years since scientists in Edinburgh cloned Dolly the sheep. Commentators at the time promised us a world overrun by cloned animals and humans. So where are they?

- Henry Nicholls

Embryologist Bill Ritchie knew that Dolly the sheep would be big news. But looking back to the days after the press got wind of the cloned sheep, he is still amazed by the sensation she caused. “By the Monday morning, the place was just full of trucks with dishes sending the news around the world,” says Ritchie, then at the Roslin Institute in Edinburgh and one of the researchers behind the creation of Dolly. “All hell had broken loose.”

One reporter imagined that Dolly might herald “a scientific explosion comparable to the atom bomb or the Moon rocket or DNA itself”. There were accusations that the scientists were ‘playing God’. Some envisaged herds of cloned sheep, consisting of thousands of identical sisters. One commentator even raised the alarming prospect that “any decent college or graduate school student could potentially clone a human being”. Others were more positive, seeing cloning as a lifeline for endangered species.

Given the excitement and such wild predictions of a future overrun by clones, it’s reasonable to ask what happened. Where are all the clones now? What worked and what didn’t? Who’s still cloning and why? Twenty years after Dolly, what is her legacy?

“Everyone thought it was going to be so easy,” says Ritchie. But it isn’t. In the case of Dolly, Ritchie succeeded in creating 277 cloned sheep cells. Of these, only 29 began to divide normally and were implanted into surrogate ewes. There was just one pregnancy that reached term. “It’s not a particularly efficient technique,” he explains. “I sometimes wonder how it works at all.”