With the likes of Kim, Putin and even Trump, one can imagine a nuke being used -- Thus, it is hard to imagine, with a shelf life of five billion years, Earth not seeing some maniac doing something stupid one day -- perhaps our best hope is democracy first, Rebecca! It is a common theme that nuclear states don't find themselves under attack [hence Kim wants nukes -- and Iran and...] Human survival might find us on Mars after all [growing potatoes in space suits -- lol]