Scientists Took a Cheek Swab From the World's Oldest Tortoise. His DNA Could Reveal Hints to Longevity

Throughout world wars, pandemics and the turn of centuries, there was Jonathan. As the world around him shifted and changed, he lived the slow life munching grass on Saint Helena, a British island territory some 1,200 miles off the western coast of Africa. The Aldabra giant tortoise is the oldest turtle in recorded history and the world’s oldest living land animal.

Caretakers don’t know his exact age, but a photograph from 1882 shows the tortoise looking fully grown, which, for his species, is at least 50 years old. This means that Jonathan would be about 194 today. He has already lived more than a century beyond his species’ 80-year average life expectancy—a feat that his safe environment, diet and medical care alone might not be able to explain.

In a new study published on Wednesday in Science Advances, researchers examined Jonathan’s DNA for genetic clues to his extraordinary age. To collect the data, Hollins propped Jonathan’s mouth open with a gloved finger and swabbed a sample of cheek cells and saliva. Key context: False reports of Jonathan’s death In April, false reports that Jonathan had died were circulated widely, stemming from a fake X post claiming to be the tortoise’s veterinarian.

It turned out to be a hoax—a ploy for cryptocurrency donations. The research team sequenced Jonathan’s DNA and identified 287 genetic variants that were unique to him. Many of these had to do with repairing damage to DNA, reducing inflammation and managing insulin.

They also found that he shared aging-related genes with species including naked mole-rats, which almost never get cancer. Additionally, they looked at Jonathan’s epigenome, the chemical tags on DNA that turn certain genes on and off. As organisms age, these switches become less predictable—tags might inconsistently attach or fall off, leading to erratic activity from genes.

The team compared Jonathan’s epigenome with those of four younger tortoises. Overall, Jonathan showed the chaos, or entropy, in the epigenome that would be expected for his age. But in the areas of the genome linked to things like DNA repair and mitochondria, the energy-producing centers in cells, Jonathan’s chemical tags were especially youthful.