Benford's themes are several. He shares with such science fiction writers as Greg Bear (Blood Music, 1985) and Bruce Sterling (Islands in the Net, 1988) the belief that humanity has reached the point where we will soon be able to make drastic changes in our bodies, enhancing our mental and physical capabilities to the point where we will appear virtually superhuman. In Great Sky River, for example, people have a built-in computer and an enhanced musculature that allows them to quite literally run all day. Benford emphasizes, however, the idea that such innovations will have little effect on our basic nature. While we will be able to achieve scientific and intellectual marvels the likes of which the twentieth century cannot yet conceive, we will nonetheless retain our current emotional strengths and shortcomings. We will never cease to be human.

Benford sharply contrasts his new, improved humanity with the Mech machine intelligences. Essentially, he is attempting to do something that may not be possible. Previous to Benford, most attempts to portray Artificial Intelligence (AI) in science fiction have involved what are essentially human beings in machine form. Most fictional AI's, from Heinlein's Mike in The Moon Is a Harsh Mistress (1966) to William Gibson's matrix AI's in Neuromancer (1984), have simply been a human intelligence, rendered faster and somewhat more logical.

Benford's point is that if true thinking machines actually do come into being, their thought processes may not be simply faster than ours, but fundamentally different, and thus beyond our comprehension. Different is not necessarily better, however, and Great Sky River, although a fairly grim novel, does contain a modicum of the determined optimism that is found in much of Benford's work. Beaten down though they may be, the men and women of Snowglade refuse to give up. They may be on the run, but they will keep running until both their legs and their cybernetic circuits give out.