During the millions of years that Ross spent in Deep Sleep, the robots advanced to the point where they could discard their physical bodies and exist as beings of pure energy. They developed a faster-than-light space drive, and when the search for life in the Solar System proved negative, they began searching other star systems. Believing that it was the kindest thing to do, they concealed all of this from Ross, only energising their old-style physical bodies whenever he was out of Deep Sleep.
Eventually, the robots discovered Fomalhaut IV, an Earth-like planet where dinosaurs were being replaced by mammals, and they guided the evolution of these mammals to the point when a humanoid species emerged so close to the original human form that interbreeding was possible. The robots argue among themselves as to whether these Fomahautans are human or merely perfect duplicates of humans. One robot, Geneticist 44/RLB/778, objects to this ‘philosophical hair-splitting’.
Ross awakes in a small spacecraft that has landed near a sandy beach where a group of people are bathing. Their skins have a slight greenish tinge, but other than that they are completely human. Ross feels that he wouldn’t mind if his sister married one – indeed he wouldn’t mind marrying one himself. (Were these greenish-skinned humanoids purely Fomahautan, or were they partly descended from Ross’s grass?)
For all their almost godlike powers, the robots still existed only to serve humans – but they could not serve humans if there were no humans left.
5B notes that Ross’s descendants will be partly human, and that the robots are very good at splitting heirs. Geneticist 44/RLB/778 respectfully suggests that Ross should not have told her about puns.