In the seventy thousand years that modern human beings have walked this earth, we ve come a long way. Art, science, culture, trade - on the evolutionary food chain, we re real winners. But, frankly, it s not exactly been plain sailing, and sometimes - just occasionally - we ve managed to really, truly, quite unbelievably f*ck things up.   From Chairman Mao s Four Pests Campaign, to the sinking of the Titanic; from the American Dustbowl, to the world s leading superpower electing a reality TV mogul as President... it s pretty safe to say that, as a species, we haven t exactly grown wiser with age.