Genome of Jonathan the Tortoise, World's Oldest Land Animal, Sequenced

Jonathan's Longevity Explored

Jonathan, an Aldabra giant tortoise, is recognized as the world's oldest living land animal, estimated to be around 194 years old. He hatched in the Seychelles archipelago around 1832 and was brought to Saint Helena in the 1880s, where he has resided since.

Aldabra giant tortoises are known for their long lifespans, but Jonathan's age significantly surpasses the typical centenarian range for his species. Researchers aimed to understand the biological underpinnings of his extreme longevity.

First Genome Sequencing

Scientists have successfully sequenced Jonathan's genome for the first time, using cheek swab samples. This genetic information was compared with that of other tortoises, including a 36-year-old named Tank, to identify genetic differences associated with aging.

The study, published in Science Advances, revealed that Jonathan possesses unique gene variants in several aging pathways. These include mechanisms for DNA repair, insulin regulation, mitochondrial function, and specific methylation patterns.

Insights into Aging Mechanisms

The research identified gene variants expected in long-lived individuals, such as those linked to DNA repair, telomere maintenance, and cellular recycling (autophagy). These findings contribute to the broader understanding of aging processes.

Stephen Clark, an aging researcher and co-author of the study, noted that understanding aging is complex and that this study represents an early step in deciphering the mechanisms behind extreme longevity.

Challenges in Sample Collection

Obtaining Jonathan's genetic material presented several challenges. Initial contact with his caretakers began in 2017, and a blood draw was deemed too risky. Samples were eventually collected via cheek swabs after coaxing Jonathan to open his mouth.

The process faced delays due to incomplete early samples, the COVID-19 pandemic, and new regulations regarding access to Jonathan. Samples were eventually transported from Saint Helena to Florida by the U.S. Space Force.