6 reasons a 194-year-old tortoise has scientists rethinking how ageing works

A giant tortoise called Jonathan is not just an animal with an extraordinary age. Scientists now think his DNA and the way it has stayed stable for nearly two centuries could help explain how some bodies resist the usual damage of ageing. Researchers say the findings could offer a rare window into extreme lifespan, with lessons that may matter far beyond one famous tortoise.

1. Jonathan is believed to be the world’s oldest living land animal

Jonathan is estimated to be 194 years old, a figure that has made him the leading contender for the title of the world’s oldest living land animal. Scientists say that alone makes him exceptional, but the bigger draw is what that age might reveal about the biology of living a very long time.

Researchers working on Jonathan say he could hold clues to reaching 200 years of age. Their conclusion is not simply that he inherited fortunate genes. They say his long life also appears to be linked to an unusual lack of the genetic wear and tear normally associated with ageing.

2. His genome contains 287 variants linked to slower ageing

The study identified 287 unique gene variants in Jonathan that appear to reduce some of the usual effects of ageing. According to the researchers, those variants influence several important bodily processes that are closely tied to long-term health.

They said these include repairing DNA damage, lowering inflammation, regulating insulin and suppressing cancer. Study senior author Dr Stephen Clark said Jonathan’s genome offers a "blueprint for cellular resilience", framing the tortoise as a natural example of how the body can remain functional over an extreme lifespan.

3. The switches controlling his genes look unusually stable

Scientists did not stop at the genetic code itself. They also examined Jonathan’s epigenome, the system of molecular switches that turns genes on and off.

When they compared Jonathan with younger giant tortoises of the same species, they found that the switches linked to DNA repair and metabolism were remarkably "very similar" to those in his younger relatives. That matters because epigenomes usually change over time, and those changes are seen as one reason ageing bodies begin to malfunction.

Cambridge University scientist Dr Justin Gerlach said the gene regulators involved in energy production and DNA repair had remained incredibly stable in Jonathan over almost two centuries.

4. The research is being described as a first for giant tortoises

The paper was published in Science Advances and marks the first time the epigenome of a giant tortoise has been investigated. It was led by scientists at Kallel, a non-profit organisation focused on longevity research.

For the team, Jonathan is not just a remarkable case study but a chance to look at how evolution may already have solved parts of the ageing puzzle. Dr Gerlach said there are few creatures that could tell scientists more about ageing than the giant tortoises of the Galapagos and Seychelles islands.

5. Jonathan’s life stretches back to the world of Darwin, Dickens and Victoria

Jonathan is an Aldabra giant tortoise believed to have hatched in 1832. That would make him a contemporary of Charles Darwin, Charles Dickens and Queen Victoria. In fact, he was born five years before Victoria succeeded to the throne.

He has spent most of his life on St Helena, the British Overseas Territory in the South Atlantic Ocean, where he lives in the grounds of Plantation House, the governor’s residence. He arrived there 144 years ago from the Seychelles, already fully grown, as a gift to the governor.

6. Scientists think his biology could point to treatments for people

The researchers say the wider goal is not just to understand one historic tortoise. Dr Clark said the aim is to turn these evolutionary insights into practical, affordable treatments for everyday people.

He argued that ageing is the biggest risk factor behind almost every chronic disease people face, and said philanthropic backing could help widen access to longevity medicine. Dr Gerlach, who has studied the ecology and conservation of giant tortoises for decades, described working with Jonathan as a privilege and said the experience feels less like studying a subject and more like collaborating with him.

That is a striking place for the science to end up. One tortoise, hatched in the early 1830s, is now being used to ask one of the biggest questions in medicine: how a body can keep repairing itself for far longer than expected.