Cloning’s ups and downs

There’s been good news and bad news about cloning of late. On the worrisome side, one of the creators of Dolly, the world’s first cloned mammal, report that the nearly 6-year-old sheep has developed arthritis in her left hip and knees. That’s early for a sheep to show such a malady, and the report renews concern that cloning may accelerate aging (SN: 4/29/00, p.