We are all planets. Is it possible for intelligent life to escape destruction, either from the planet or ourselves? Or are we destined for extinction like 99% of all species before us? Our best chance of survival may be to escape earth and build another colony somewhere else. But there are real barriers: space radiation, microgravity and the bacteria inside us will conspire against us. And our DNA is coded for the conditions here on earth, so if we ever manage to colonize another planet those who are born there will evolve into another species.