The first full mammal was cloned in 1996, a feat that had previously been believed to be impossible. In Edinburgh, Scotland, a sheep was cloned from the cell of an adult. Cloning is made possible by replicating the DNA sequence from the strands within the nucleus of each cell. The newly cloned sheep was named Dolly. The scientists who achieved this, Ian Wilmut and Keith Campbell, announced their success to the world in 1997. This accomplishment led to cloning in other species. However, research in the cloning of humans has been limited because of ethical concerns.

*Pictures from Microsoft Electronic Encarta Encyclopedia Standard Edition 2002.