This week on the Naked Scientists, we're probing the origins of man and pursuing the spread of humans around the world. We find out how to date a hobbit, discover how an enormous flood formed the English Channel, and examine the evidence for when ancient humans first used fire. We also tune into the world's smallest nano-sized radio, talk to the two men who flew over Mt Everest on paragliders and in Kitchen Science, we show you how to re-light your fire!