Humans with a lot of time on their hands, plenty of food, shelter and not a lot to do have the tendency to feel guilty about being on the planet. They have the non-luxury of being able to think too much about what it is we’re really up to here – we eat, sleep, reproduce, expel waste and try to stay alive, sometimes shamefully – and it drives them nuts. Makes them angry, depressed. Of course it does. Our lives, if you can afford to dwell on it, basically come down to a lot of obnoxious chewing, flaking, heavy breathing and crying. The same goes for most creatures on earth. Except we humans have figured out how to hack it out the best, or worst, depending on who you ask.