On February 27, 1997, the world learned that Dolly was a clone. Guided by Ian Wilmut and colleagues from the Roslin Institute in Scotland, they announced that they had succeeded in giving birth to a sheep that had originated from a cell taken from an adult sheep. This made her the identical twin of a sheep that was six years older! Just as amazing is the fact that she has no father. Although there were some who doubted that the procedure had been reported accurately, subsequent cloning successes with other animals (i.e. cattle, mice) have proven the power of the technology.