194-Year-Old Animal: Researchers Uncover the Longevity Secrets of the World’s Oldest Land Animal

For the first time, researchers have sequenced the genome of Jonathan, the giant tortoise revered as the oldest living land animal on Earth. The findings shed light on the reasons behind his extraordinary longevity.

Nearly Two Centuries on This Earth

After Napoleon Bonaparte, this Aldabra giant tortoise (Aldabrachelys gigantea) is perhaps Saint Helena’s most famous resident in the South Atlantic. It is thought that Jonathan arrived on the island in 1882, when he was already around fifty years old, which would place his current age at roughly 194 years.

While the average lifespan of A. gigantea is estimated at 80 years, over the decades researchers noticed that many individuals far exceeded it. To learn more, Stephen Clark and his colleagues carried out the very first genetic sequencing of the oldest terrestrial animal.

Because Sainte-Hélène authorities declined their request for blood samples due to the risk of infection to the tortoise, the team instead used saliva samples and buccal swabs, which are more prone to bacterial contamination. Compare this approach to solving a puzzle: they meticulously pieced together usable DNA fragments and filled in the missing sections by drawing on spectra from another Aldabra tortoise.

Comparing its genome with those of four other individuals of its species uncovered 287 genes harboring mutations unique to Jonathan. Of these, 41 were deemed functionally significant and 12 also associated with longevity in other animal species. Notably, some regions of its DNA linked to mitochondrial function—the cellular power plants—displayed features similar to those of a five-year-old specimen of A. gigantea.

An Exceptional Resilience

According to the authors of the new study, published in the journal Science Advances, these particular traits would help Jonathan’s body counteract the deleterious effects of aging, especially by promoting DNA repair, which helps limit cancer risk.

The fact that some of the tortoise’s near-bicentennial genetic mutations are close to those identified in human supercentenarians further reinforces the idea of a universal aging.

Last year, researchers in Barcelona had also reported exceptional mitochondrial function in Maria Branyas, the former oldest person in humanity who passed away at age 117 in 2024.