Giant tortoises are a recent evolutionary innovation and used to be everywhere, not just on islands. It’s impossible to age them accurately unless you know when they hatched. They are actually pretty slow.Giant tortoises are a recent evolutionary innovation and used to be everywhere, not just on islands. It’s impossible to age them accurately unless you know when they hatched. They are actually pretty slow. The ones Darwin saw were fast, but only because he was probably chasing them.