As the first cloned mammal ever to be created from an adult cell, her birth was of huge excitement both to the scientific world and to the public.
The development of cloning technology was an extension of the Roslin Institute's interest in the application of transgenic technology to farm animals. Transgenesis is the process of introducing an external gene, called a transgene, into a living organism so that the organism will display a new trait, which it may then pass on to its offspring. Transgenesis has been practised on mice since the early 1980s, producing so-called 'super mice' through a very sophisticated genetic modification technology using embryonic stem cells.
Since embryonic stem cells had not been isolated from farm animals, this method of genetic modification was not available. Cloning was therefore a potential alternative way of achieving the same end.
As with all other cloned animals, Dolly started her life in a test tube. Once normal development was confirmed at six days, the embryo, which was eventually to become Dolly, was transferred into a surrogate mother. The pregnancy went without a problem and Dolly was born on 5 July 1996.
The birth of Dolly was kept under wraps until the publication of the Roslin Institute's research results could be prepared. Once these results were released, the full impact of the discovery became plain, as the world’s press descended on Roslin.
In an attempt to allow Dolly to have as normal a life as possible, it was decided that she should be allowed to breed. A small Welsh mountain ram was selected as her mate and between them they successfully produced six lambs. Their first lamb, Bonny, was born in the spring of 1998. Twins followed the next year and triplets the year after that.
Dolly as a lamb with her surrogate mother. © Roslin Institute.
Dolly and her first lamb Bonnie. © Roslin Institute.
Dolly the sheep being scanned. © Roslin Institute.
In the autumn of 2001, Dolly was seen to be walking stiffly. X-rays confirmed that Dolly did indeed have arthritis. It fueled the suspicion that cloned animals were destined to age prematurely. The cause of the arthritis was never established but daily anti-inflammatory treatment resolved the clinical signs within a few months.
Although the arthritis was a concern for the animal carers at Roslin, a much more serious problem was feared. In January 2000, another cloned sheep, Cedric, died. The post mortem revealed that Cedric had died of sheep pulmonary adenomatosis (SPA). This disease is caused by a virus that induces tumours to grow in the lungs of affected animals and is incurable.
Dolly remained healthy until Monday 10 February 2003, when an animal care worker reported that he had noted her coughing. Full veterinary examinations and blood tests were conducted but failed to establish a diagnosis. A CT scan was carried out on 14 February 2003. The scan confirmed the team's worst fears: tumours were growing in Dolly's chest.
Since a general anaesthetic had been necessary to perform the CT scan it was decided that it would be best if Dolly did not regain consciousness and she was put to sleep.
Dolly was important because she captured the public imagination. The idea that there might be an exact copy of oneself somewhere in the world is a theme that has been often pursued in science fiction and the prospect that it might be possible to clone a human being has excited a lot of speculation and interest.
Likewise, plans to clone extinct species such as mammoths have attracted a lot of publicity, but at present such ideas must remain, like Jurassic Park, firmly in the realm of fiction.
This short animation about Dolly was made by young volunteers at National Museum of Scotland working with curators from our Science and Technology department and animator Cameron Duguid.
Dolly and the Atom Smasher was designed and made as part of a National Museums Scotland project, Game Jam, which brought together schools pupils, game developers and museum objects. Pupils from Craigie High School in Dundee worked with Dundee Games Collective (DGC) and staff from the museum’s Community Engagement team.
As part of the celebrations for the opening of ten new galleries at the National Museum of Scotland, the Young Demonstrators worked with artist Henry Cruickshank to create a comic strip starring Dolly. You can see the completed comic in the slideshow below, or download it here. You can find out more about the project and see images drawn by our visitors here.