 Great question. Dogs are an amazing model. If you go to the dog park and look around, there are dogs that look like Strider, but there are tiny dogs and giant dogs and couch potato dogs and sprinting dogs. Huge variation. That's true as well for aging. There are short-lived breeds and long-lived breeds. There are breeds that are at risk of cancer, while other breeds are protected from cancer but at risk of heart disease and so on. That variation...