Why It Matters That Dolly The Sheep's Cloned 'Sisters' Are Healthier
Daisy, Debbie, Denise and Dianna are alive and well at 9 years old.By Grant Suneson | July 26, 2016
In 1996, Dolly the sheep became the world's first mammal cloned from an adult cell.
Scientists fused the DNA from one sheep with an egg from another to create an embryo that eventually became Dolly.
Sadly, Dolly didn't live to see her seventh birthday because of a lung disease. She also seemed to age much quicker than an average ewe, suffering from early onset osteoarthritis and joint problems.