In a game of Russian roulette with a standard Colt revolver, the chances of instant death are one-in-six. Terrifyingly, that’s the same as the odds of humanity being wiped out within 75 years – everyone dead in a cataclysmic and total breakdown of civilisation, according to Oxford University futurologist Toby Ord, an expert on the threat of artificial intelligence. Does it sound impossibly bleak? His colleague Nick Bostrom is more pessimistic still. He rates the possibility of human extinction by the next century as one in four. Pulitzer prize-winning writer Jared Diamond is even less hopeful, predicting our species’ chances...