Dolly was probably the most famous sheep in the world because she was the first mammal to be cloned from an adult cell.
She was created by a research group led by British embryologist Ian Wilmut and born on 5 July 1996. Her DNA came from an adult sheep’s mammary gland cell, and she was named after the country singer Dolly Parton. The fact that she was cloned means she only had one parent and they were genetically identical.
Cloning animals is a very difficult process and the success rate is very low. It took 277 attempts to create Dolly, and her birth was a huge scientific achievement, proving that a cell taken from a specific part of the body could recreate a whole individual.
When Dolly was one year old, an analysis of her DNA showed that she was ageing faster that it would be expected for a normal sheep at the same age. Some scientist believe that her premature ageing resulted from the fact that her DNA had come from an adult sheep, and it could have meant that Dolly was ‘older’ than her actual age.
Dolly led a normal life with the other sheep at The Roslin Institute, where she had been cloned. Over the years she had a total of six lambs. Interestingly, most sheep live for 10-12 years, however Dolly was put to sleep at the age of six, on 14 February 2003, because she had lung cancer and severe arthritis.
Cloning is a very controversial issue and many countries passed laws to ban human cloning.