---
title: "Scientists Sequence Genome of Jonathan, the 194-Year-Old Tortoise"
description: "The world’s oldest living land animal carries unusual gene variants tied to DNA repair, telomeres and a surprisingly youthful mitochondrial methylome"
author: "rews desk"
published: 2026-10-07T18:00:38Z
modified: 2026-10-07T18:34:49Z
url: https://rews.cc/a/scientists-sequence-genome-of-jonathan-the-194-year-old-tort-a2a49d
language: en
tags: ["biology", "aging", "genetics", "tortoises", "longevity", "science"]
publisher: "Rews (https://rews.cc)"
---

# Scientists Sequence Genome of Jonathan, the 194-Year-Old Tortoise

*The world’s oldest living land animal carries unusual gene variants tied to DNA repair, telomeres and a surprisingly youthful mitochondrial methylome*

By rews desk · October 7, 2026 · https://rews.cc/a/scientists-sequence-genome-of-jonathan-the-194-year-old-tort-a2a49d

## In brief

- Scientists sequenced the genome of Jonathan, a roughly 194-year-old Aldabra giant tortoise and the oldest living land animal
- The study, published Wednesday in Science Advances, found unique gene variants across most known aging pathways
- Jonathan’s mitochondrial methylome looked more like a five-year-old tortoise’s than his own aged genome’s
- Obtaining the DNA took years of negotiation with Saint Helena caretakers; a U.S. Space Force flight carried the samples
- Researcher Stephen Clark said the work at Kallel Labs aims to find targets that could extend human healthspan

Scientists have sequenced the genome of Jonathan, the roughly 194-year-old Aldabra giant tortoise who is the world’s oldest living land animal, and found a batch of unusual gene variants that may help explain how he has survived nearly two centuries, according to a study published on Wednesday in *Science Advances*.

Jonathan hatched around 1832 in the Seychelles and was already in his twenties when Charles Darwin published *On the Origin of Species*. In the 1880s he was shipped, with three other tortoises, to the remote island of Saint Helena as a gift to the British colonial governor, and he has lived at the governor’s residence, Plantation House, ever since. As [404 Media reported](https://404media.co/oldest-living-land-animal-jonathan-the-tortoise/), he and his fellow tortoises are now one of the island’s tourist attractions.

Aldabra giant tortoises often live past 100, but Jonathan is an outlier even by their standard. To look for the source of his staying power, the researchers swabbed his cheeks and compared his genome with those of several younger tortoises, including a 36-year-old named Tank.

The sequencing turned up what the study called unique gene variants in most of the known aging pathways, including DNA repair, insulin regulation and mitochondrial function. Many of the variants were ones the team expected, based on earlier studies of long-lived animals and people: genes tied to DNA repair, to the upkeep of telomeres, the sequences that protect the ends of chromosomes, and to autophagy, the process by which cells recycle their own worn parts.

The surprise came in Jonathan’s methylome, the set of chemical marks that help control how genes are expressed. Most of his showed the wear, or entropy, the team would expect of a 194-year-old. But the portion tied to the mitochondria looked unusually clean, more like that of a five-year-old tortoise the researchers used for comparison.

“Jonathan’s really the first of his kind to have this analysis, and we were also able to do the methylome for the younger tortoises,” Stephen Clark, an aging researcher at the nonprofit Kallel Foundation and an author of the study, said in a call with 404 Media. “We actually compared him to a five-year-old tortoise, so we had 189 years of difference between the methylomes. No one’s ever done that, even in humans, because no humans live that long.”

That gap, Dr. Clark said, was the point of the exercise. “That was one of the main things we were excited about: how does this methylome change with age?” But he cautioned that the mitochondrial finding is a lead, not an answer, and that confirming it will take more work. “Aging is very complicated, and there’s all these different hallmarks,” he said. “That’s why this Jonathan study is so interesting. We’re still just at the very beginning of trying to understand aging.”

Getting Jonathan’s DNA at all took years. Dr. Clark first contacted his caretakers in 2017, but a blood draw was judged too risky for the old tortoise, so he had to be coaxed into opening his mouth for a swab. Early samples came back incomplete, the Covid pandemic intervened and new rules limited access to Jonathan. In the end the samples traveled from Saint Helena to Florida aboard a U.S. Space Force flight.

The team has a commercial aim behind the curiosity. “We’re interested in long-lived species like Jonathan because we can hopefully find other targets,” Dr. Clark said of the work at Kallel Labs. “The ultimate goal of the company is to affect human healthspan and lifespan.”

Jonathan, meanwhile, grazes on at Plantation House. Saint Helena is also known as the island of Napoleon Bonaparte’s exile; the former emperor died there only about a decade before Jonathan is thought to have hatched.