Dolly the Sheep's Clone 'Sisters' Are Healthy in Old Age

Four cloned sheep that are genetically identical to Dolly, the first cloned mammal, are still healthy even in old age, a new study found. The four sheep, which were derived from the same batch of cells as Dolly and could be considered her clone "sisters," have just reached their 9th birthday, which is equivalent to age 70 in human years, researchers who have been studying the sheep said. All of the sheep were free from many diseases commonly found in older sheep, such as diabetes and high blood