But the new study, which tracked four sheep cloned from the same ewe as Dolly, found they had aged normally.
Some of the animals did show mild — and in one case moderate — signs of osteoarthritis. But the researchers say that it was not sufficiently severe that any of the animals required treatment.
Dolly the sheep’s “siblings” are generally healthy, a study has shown, providing hope that cloning can yield animals free from degenerative illness.
The first mammal to be cloned from an adult cell — Dolly — died at the relatively young age of 6.5 years, having suffered from osteoarthritis.
This raised concerns that cloned animals might age more quickly.
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