194-year-old tortoise reveals stable gene switches that may help resist aging
Researchers studying a giant tortoise named Jonathan say it's not just good genes but a lack of genetic wear and tear that has kept him going for nearly two centuries.
In a study published in the journal Science Advances, scientists have pinpointed 287 unique gene variants in this remarkably old giant tortoise that reduce the usual effects of aging. These control key processes in the body, including repairing 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 the 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.
Gene switches resist the aging process
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 aging 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 nonprofit Kallel in the U.S., who say that cracking the genetic code of a multicentury life offers unprecedented insights into extreme longevity.
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. Credit: Joe Holland
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. Credit: Joe Holland
Jonathan arrived in St. Helena as a gift to Sir William Grey-Wilson in 1882, who later became governor of the island. This image was taken around that time - Jonathan is on the left. Credit: A.L. Innes