Jonathan the tortoise is 194 years old and thriving. His genes help explain why.

He lived at the same time as Charles Darwin, Queen Victoria, and President Andrew Jackson. He’s a gay icon, who was alive before Thomas Edison patented the lightbulb. At 194 years old, Jonathan the Aldabra giant tortoise (Aldabrachelys gigantea) is the world’s oldest known living giant tortoise and oldest land animal. But what is helping Jonathan stay alive this long? Good genes alone are not responsible for Jonathan’s longevity but a lack of genetic wear and tear appears