Two decades ago, the birth of Dolly the sheep was a huge breakthrough for the scientific community. Cloned by researchers Sir Ian Wilmut, Keith Campbell and colleagues at the Roslin Institute in Scotland, Dolly's birth on 5 July 1996 sparked excitement around the globe, with promises of medical advances in treating diseases.
Although several clones of frogs, mice and cows had been previously cloned in the laboratory using DNA from embryos, Dolly was remarkable as she was the first mammal to be cloned from an adult somatic cell using the process of nuclear transfer. Although neither the hopes of medical treatments nor fears of human cloning have materialised since Dolly, some scientists say her cloning has made a significant impact on stem cell research.
Twenty years on, test your knowledge on Dolly the Sheep with our quiz: