Jonathan the tortoise is about 194 years old, and his genes may explain why

Jonathan, an Aldabra giant tortoise weighing about 400 pounds, is roughly 194 years old, which makes him the oldest known living land animal. He arrived on the island of St. Helena in 1882 as an adult and has lived around a century longer than others of his kind. Collecting his DNA was tricky: his veterinarian, Joe Hollins, tempted him with fresh greens and quickly took a sample of cells from inside his cheek. After sequencing it, scientists found youthful gene activity that may help account for his exceptionally long life.