Dolly (sheep)

Lore & Background

Dolly was created by Keith Campbell, Ian Wilmut and colleagues at the Roslin Institute, part of the University of Edinburgh, and PPL Therapeutics. The cell used as the donor was taken from a mammary gland; Wilmut stated the name came from Dolly Parton. She had three mothers: one provided the egg, another the DNA, and a third carried the cloned embryo. Dolly was born on 5 July 1996, and her existence was announced on 22 February 1997.

Dolly lived her entire life at the Roslin Institute in Midlothian. She was bred with a Welsh Mountain ram and produced six lambs: Bonnie (1998), twins Sally and Rosie (1999), and triplets Lucy, Darcy and Cotton (2000). At age four she developed arthritis, treated with anti-inflammatory drugs. On 14 February 2003 she was euthanised due to progressive lung disease and severe arthritis. A post-mortem revealed ovine pulmonary adenocarcinoma, a common disease in sheep; Roslin scientists stated no connection to cloning was found. Her body was preserved via taxidermy and is displayed at the National Museum of Scotland in Edinburgh.

Reader's Guide

Dolly's cloning demonstrated that genes in a mature differentiated somatic cell could revert to an embryonic totipotent state, enabling the creation of a whole individual. This breakthrough led to advancements in stem cell research, including the discovery of induced pluripotent stem cells. After Dolly, many other large mammals were cloned, including pigs, deer, horses, and cattle, and cloning has been explored for preserving endangered species and reviving extinct ones, such as the Pyrenean ibex cloned in 2009. The technique was highly inefficient in 1996—Dolly was the only lamb from 277 attempts—but success rates improved over time. Scientific American concluded in 2016 that Dolly's main legacy is in stem cell research rather than animal cloning. The first successful cloning of a primate species using the same method was reported in January 2018, and gene-edited monkey clones followed in 2019. Dolly's cloning also spurred ethical debates and popular culture references, such as the Brazilian telenovela O Clone (2001).

Did You Know?

• Dolly was not the first animal to be cloned; the first animal cloned from an adult cell was Dolly.
• Her name was inspired by Dolly Parton because the donor cell came from a mammary gland.
• She produced six lambs in total: one, twins, and triplets.
• A 2016 study of thirteen cloned sheep, including four from Dolly's cell line, found no evidence of detrimental long-term effects from cloning.