A new genetic analysis of Jonathan, a giant tortoise believed to be 194 years old, has uncovered possible clues about exceptional longevity. Researchers say the findings could eventually inform treatments intended to slow cellular decline related to aging in humans.

Jonathan is the world’s oldest land animal and an Aldabra giant tortoise, a species native to the Seychelles islands in the Indian Ocean. He has spent most of his life on St. Helena, a British Overseas Territory in the South Atlantic.

Giant tortoises commonly survive for more than a century, but Jonathan is extraordinary even within this remarkably enduring group. The research, published Wednesday in Science Advances, investigated whether the animals’ slow pace extends to activity inside their cells.

Study coauthor Justin Gerlach, a biology fellow at the University of Cambridge in the United Kingdom, said giant tortoises have long been assumed to possess very low metabolic rates. Slower cellular processes could mean fewer chemical reactions and less damage to cells and DNA.

Researchers examined Jonathan’s genome, his complete set of DNA, and his epigenome, which includes the switches controlling whether genes are active. They identified 287 gene variants associated with protecting him from cellular damage that accumulates over time.

“He does have some genes that are particularly good for DNA repair and reducing inflammation,” Gerlach said. Both mechanisms are known to slow aging processes, while the analysis also suggested Jonathan continues expressing appropriate genes at suitable levels despite his advanced age.

That regulatory process usually deteriorates much earlier in humans and most other animals. Gerlach said Jonathan retains the genetic controls of a much younger animal, although researchers do not yet know whether that quality is unique to him or typical among giant tortoises.

Scientists know that certain whales, sharks and clams also reach exceptional ages, but the genetic and molecular forces determining lifespan remain poorly understood. Joao Pedro de Magalhaes of the University of Birmingham said understanding these differences could represent a major advance in aging and longevity research.

Jonathan’s exact age remains uncertain. Scientists estimated he was about 194 by studying an 1882 photograph showing him already at adult size, which giant tortoises typically reach at approximately 50 years old.

St. Helena’s governor gave Jonathan an official birthday in 2022, setting it as December 4, 1832. Gerlach said the tortoise could actually be 200 or older, but the estimate already places his birth during the youth of Abraham Lincoln, Charles Darwin and Queen Victoria.

Jonathan weighs about 400 pounds, or 180 kilograms, and remains active despite losing his sight to cataracts. Earlier this year, a viral April Fools’ Day joke falsely claimed he had died, leading the St. Helena government to confirm that he remained alive and well.

Because of Jonathan’s age and the need to minimize infection risks, researchers collected DNA by swabbing his mouth instead of drawing blood. The resulting saliva samples prevented the team from using more accurate DNA sequencing methods.

The researchers compared Jonathan’s DNA and epigenome with those of much younger Aldabra giant tortoises from the Aldabra Atoll in Seychelles. They found striking similarities, while his mitochondria, the cellular structures responsible for producing energy, appeared to be in surprisingly optimal condition.

Senior study author Dr. Stephen Clark, founder of the Nashville based Kallel Foundation, said the team wants to determine whether Jonathan’s mitochondrial condition is common across his species. Clark also said researchers are interested in drugs that improve human mitochondrial health and hope to bring such drugs into human clinical trials within one or two years.

The study’s reliance on a single animal limits what researchers can conclude about the reasons for Jonathan’s longevity. Handan Melike Dönertaş of Middle East Technical University said comparisons involving more extreme individuals and additional species could help scientists identify what makes them exceptional.

Vincent J. Lynch of the University at Buffalo called Jonathan an ideal subject but warned that some methods used in the study can produce false positive and false negative results. Ylenia Chiari of the University of Nottingham nevertheless said the findings add to research exploring exceptional longevity and its possible relevance to human aging and cancer research.