Jonathan, a giant tortoise estimated to be 194 years old, still carries surprisingly youthful chemical patterns in parts of his DNA that help cells produce energy, researchers have found.
The finding could help scientists investigate how some animals survive for nearly two centuries. It does not establish why Jonathan has lived so long or show how to extend human life.
The study, published Oct. 7 in Science Advances, examined Jonathan’s genetic code and the chemical tags that help regulate his genes. Researchers found that some regions associated with cellular energy production showed less disorder than expected for an animal of his age. These regions help control mitochondria, the structures that supply cells with energy.
The team also identified distinctive genetic variants involving DNA repair, inflammation, insulin regulation and cancer suppression. Those processes help the body repair damage and keep cells functioning, making them candidates for further investigation into Jonathan’s longevity.
Jonathan lives on the grounds of Plantation House, the governor’s residence on Saint Helena, a British territory in the South Atlantic. He arrived from the Seychelles in 1882 already fully grown. His estimated birth year, 1832, puts him among animals alive during Charles Darwin’s lifetime; his exact hatch date is unknown.
Obtaining his DNA required special care. Island officials declined a request for a blood sample because of concerns about his health. Veterinarian Joe Hollins instead collected tissue from inside Jonathan’s cheek for the researchers to analyze.
The team compared chemical patterns in Jonathan’s DNA with those of younger tortoises of the same species. That comparison offers a starting point, but further research must establish whether the findings reflect Jonathan’s individual biology or traits common to giant tortoises.
Jonathan’s long life has not spared him every effect of aging. He is blind from cataracts, although he retains excellent hearing. Researchers plan additional studies of long-lived animals to test whether the patterns found in his DNA consistently accompany exceptional longevity.