On this day in 2003

Dolly the sheep was a scientific marvel, being the first mammal cloned from an adult cell. However, she wasn’t the first mammal created through cloning in history: that honour went to another sheep that was cloned from an embryo cell almost 20 years earlier.

Dolly was cloned at the Roslin Institute, which is part of the University of Edinburgh and her existence was announced to the world in February 1997. By that point she was around seven years old. She had started out as a single cell taken from the udder of an adult Finn Dorset sheep, which was combined in the laboratory with an unfertilised egg, and implanted in a surrogate mother to develop.

Born older than she was

The result, Dolly, was genetically identical to the sheep from which the original udder cell had been extracted – and that included her age. Sample analysis performed one year later showed that Dolly was biologically older than her chronological existence would suggest, with her DNA resembling that of a much older animal. By 2001 she had developed arthritis, and scans performed two years later revealed tumours in her lungs. She was euthanised on 14 February 2003 and her body donated to the National Museum of Scotland. She had given birth to six lambs during her lifetime.

By the time of her death, Dolly was just one mammal among many to have been cloned using cells taken from an adult, and scientists were already warning against cloning humans who, they said, would likewise suffer an early death.