Researchers studying a giant tortoise named Jonathan say it's not just good genes, but lack of genetic wear and tear that have kept him going for nearly two centuries.
In a study published today in the journal Science Advances, scientists have pinpointed 287 unique gene variants in this remarkably old giant tortoise that reduce the usual effects of ageing. These control key processes in the body including repair of DNA damage, reducing inflammation, regulating insulin, and suppressing cancer.
Jonathan, an Aldabra giant tortoise (Aldabrachelys gigantea), is estimated to be 194 years old. This makes him the oldest living giant tortoise, and oldest land animal, in the world today. He's thought to have hatched in 1832 - making him a contemporary of Charles Darwin and Queen Victoria.
The team also compared the giant tortoise's epigenome - the 'on/ off' switches on his genes - with those of younger giant tortoises of the same species. Remarkably, they found the switches controlling Jonathan's DNA repair and metabolism genes were very similar to those in his younger relatives. Usually, the epigenome changes over time, contributing to the ageing process - this is a key reason why things start to go wrong in older bodies.
This study marks the first time the epigenome of a giant tortoise has been investigated. It was led by researchers at longevity research non-profit Kallel in the US, who say that cracking the genetic code of a multi-century life offers unprecedented insights into extreme lifespan.
"We found that the gene regulators involved in energy production and DNA repair have remained incredibly stable in Jonathan over almost two centuries," said Dr Justin Gerlach at Peterhouse at the University of Cambridge, who was involved in the study.
He added: "There are few creatures that could tell us more about ageing than the giant tortoises of the Galapagos and Seychelles islands. Working with a really old giant tortoise is such a privilege: you get a sense of the tortoise being your collaborator, not your study subject."
Gerlach has studied the ecology and conservation of giant tortoises for several decades, but this is the first time he has studied their exceptionally long lives.
"Nature has already solved the puzzle of aging in remarkable ways, and Jonathan's genome provides a blueprint for cellular resilience," said Stephen Clark MD, PhD, founder of Kallel and senior author of the study.
He added: "Our goal is to take these evolutionary insights and immediately translate them into practical, affordable treatments for everyday people. Aging is the greatest risk factor for nearly every chronic disease we face, and through the generosity of philanthropic partners, we can democratise access to longevity medicine."
Jonathan has lived most of his life on the island of St Helena, a British Overseas Territory in the South Atlantic Ocean, in grounds of Plantation House - the residence of the governor of St Helena. He arrived from the Seychelles 144 years ago, already fully grown, as a gift to the governor.
The giant tortoises of the Galapagos and Seychelles islands are the extraordinary last survivors of animals that used to dominate the ecology of many of the world's islands.
