Welcome to the fractured future, at the dusk of the 21st century. Earth has a population of roughly a billion hominids. For the most part, they are happy with their lot, living in a preserve at the bottom of a gravity well. Those who are unhappy have emigrated, joining one or another of the swarming dense-thinker clades that fog the inner solar system with a dust of molecular machinery so thick that it obscures the sun. The splintery meta-consciousness of the solar-system has largely sworn off its pre-post-human cousins dirt side.