Mass Extinction! 250 million years ago nearly all life on Earth ended. Back from the brink, history then repeated itself with the disappearance of the dinosaurs 60 million years ago. So are we next? Plus news of how a comet smash could have kick-started life on Earth, whether e-cigarettes are safe, and why science and medical reporting in the media might be untrustworthy... Like this podcast? Please help us by supporting the Naked Scientists