Sheep Astray

Two Decades After Dolly, Mammalian Cloning Closes in on Humans

She would have turned 20 last July. She died in 2003 in the same place where she was born—Edinburgh, Scotland. Oddly, she had three mothers and no father. Yet her birth announcement rocked the world. As you may have guessed, I'm referring to Dolly the sheep, who was the first mammal cloned from an adult.

Dolly's birth, on July 5, 1996, caught everyone by surprise when it was announced months later. At the time, most scientists predicted it would be at least 15 to 20 years before the first mammal was cloned.¹ There had been little serious discussion of cloning in the scientific communities, though ethicists had raised some concerns. But every time they brought up the...