How has "humanity" been improved in the novel, Great Sky River?

On the planet Snowglade, there was a golden age during which human beings drastically altered their own bodies through cybernetic improvements and DNA restructuring. That near-utopian period ended, however, due to the onslaught of the Mechs, a robot civilization descended, perhaps, from the robotic intelligences of Walmsley's day. Now humanity is nearly extinct, its few remnants, although still superhuman in terms of their physical capabilities, caught up in a hopeless, nomadic lifestyle.