Dollysheep

Dolly the sheep, the first mammal cloned from an adult somatic cell, was produced at the Roslin Institute in Scotland and announced to the world in 1997. The work was led by Ian Wilmut and Keith Campbell, among others. Dolly's creation demonstrated that specialized adult cells could be reprogrammed to form a complete organism, a breakthrough in cloning research.

Dolly was created using somatic cell nuclear transfer, a technique in which the nucleus of an adult cell is transferred into an enucleated egg cell and stimulated to develop into an embryo for implantation into a surrogate mother. The clone is genetically nearly identical to the donor, with differences arising from mitochondrial DNA in the egg donor.

Dolly was named after the singer Dolly Parton, in reference to the mammary gland from which the donor cell was taken. Born in 1996, Dolly lived at the Roslin Institute until she was euthanized in February 2003 following a progressive lung disease, at about six years old.

Dolly’s birth highlighted the technical feasibility of cloning mammals and spurred advances in cloning technologies for animals, with potential applications in medicine and agriculture as well as substantial ethical and welfare concerns. Her case also fueled debate about the health implications of cloning. Some discussions focused on whether donor cell age might cause accelerated aging in clones, prompting further study of telomere length, but subsequent analyses yielded mixed results and no clear consensus emerged.