Stephen J. Gould once said that he was frequently asked what he thought the future of human evolution would be like. His answer was that we are not going anywhere. His theory of punctuated equilibrium holds that when a species has a large population and is widespread it is pretty well adapted to its environment and is not under selective pressure to change. It is when the environment changes or something else happens to severely reduce the population orr to isolate a small subpopulation from the larger population that evolutionary change comes about. He said that short of a worldwide disaster or a science fiction like scenario like a lost space colony humans are just not under any pressure to evolve in the foreseeable future.
Well, Stephen Baxter supplies the pressure in this novel. It is a severe ecological breakdown brought about mainley by anthropogenic global warming. He postulates that humanity does survive, even if barely, and evolution does take place. Not only that, but interstellar travel is also postulated giving rise to a version of the lost space colony too. Any attempt to predict how humans would evolve under such circumstances would be purely speculative, but then, this is a story of speculative fiction. It is also a quite enjoyable and interesting read.