Dolly's Clones are ageing fine!

 Four clones of a cloned sheep have made it to their ninth birthday without issue

Twenty years ago, Dolly the sheep was born. The first mammal to be successfully cloned from an adult may have kickstarted a whole new chapter in cloning, but it also didn’t live very long. Ill health and a premature death at the age of six-and-a-half raised concerns about the sustainability of clones. 

Now a study into a second batch of cloned sheep, including a number of direct duplicates of Dolly, has shown this isn’t the case. The cohort of 13 cloned sheep, including the four “Nottingham Dollies” (Debbie, Denise, Dianna and Daisy), underwent extensive muscular and skeletal investigations, with X-ray and metabolic tests assessing glucose tolerance, insulin sensitivity, and blood pressure. Compared to a group of naturally bred six-year-old sheep, they were all judged to be healthy, except for one that had developed mild osteoarthritis. 

Crucially, all of the tested clones have surpassed Dolly’s lifespan of 6.5 years. Before she was euthanised, Dolly had developed progressive lung disease and severe arthritis, and this raised concerns that the health of cloned animals could never match one born naturally. It now seems that Dolly’s condition was something of an outlier, and may have been a symptom of being raised indoors rather than any issues with the cloning process.