Dolly’s Descendants Healthy Into Old Age, Scientists Find

The '90s are alive and well in a British laboratory.

Researchers in the U.K. have found that relatives of Dolly, who became famous in 1996 as the first mammal to be cloned, are healthy even into old age, allaying fears among some that genetic copies may begin to suffer ailments associated with aging sooner than their naturally bred counterparts.

Dolly's Relatives | Photo Courtesy of the University of Nottingham

Created in Edinburgh, Scotland, Dolly died in 2003 at just over 6 years old. The average lifespan of a sheep is about 10 years, and Dolly had been undergoing treatment for arthritis and lung disease. Her early death led some to speculate that the cloning process could cause health issues well into adulthood.

But that doesn’t seem to be the case, according to a study written by the researchers and published July 26 in the journal Nature Communications.

Scientists examined blood sugar levels, blood pressure, and muscular and joint health of 13 cloned sheep. Four of those came from the same batch of DNA as Dolly and were created between 2005 and 2007 using somatic-cell nuclear transfer (SCNT), the same procedure used in 1996.

“We could find no evidence, therefore, of a detrimental long-term effect of cloning by SCNT on the health of aged offspring among our cohort,” the researchers said.

The study is first to examine the health of cloned animals at such an advanced age relative to their species. Researchers said that though animals who survive into adulthood showed no signs of cloning-related health issues, a high proportion of embryo’s fail to make it to term.

When news first broke that scientists had cloned Dolly, the public had mixed reactions. Some hailed it as a major step in medicine and agriculture; others said it was a slippery slope to human cloning. In 2003, the Food and Drug Administration said that cloned animals were safe for human consumption, but the use of cloned animals for meat never caught on.

Dolly was the subject of a U.S. court case over whether the Roslin Institute at the University of Edinburgh, which performed the cloning procedure, could patent the sheep. In 2014, the U.S. Court of Appeals for the Federal Circuit rejected the patent application, finding that the requirement for “markedly different characteristics” in an organism can’t be met when the invention claimed—in this case Dolly—is identical to the donor animal.