The 100,000 years since the monolith visited earth saw no new inventions among the man-apes, but they were refining their tools and learning to use them better. Their teeth became smaller as they further relied on tools; consequently, their jaw became more refined-the first step toward speech. Ice ages came and went and the descendents of the man-apes further developed their physical and mental abilities. At the end of this long process was man. The first men had no more advanced tools than the man apes, but they had speech and were able to share knowledge and pass it to the next generations. They began to develop more powerful tools and materials. He invented writing, philosophy, and religion. His weapons increased in scope-spears gave way to guns, which gave ways to guided missiles and nuclear warheads. These weapons had helped man conquer the world, but "as long as they existed, he was living on borrowed time."
The book begins by describing creatures, "man-apes," who are the biological predecessors of humans. The narrator is omniscient, capable of describing the internal mental states of these creatures in ways they would not think. For instance, at the start of the book we are told that Moon-Watcher feels "a dim disquiet that was the ancestor of sadness." This type of talk is strange and unsettling to most people. We are not used to confronting the fact that we were evolved from "lower" beings in this way. By taking this perspective on the man- apes, the narrator jars us, putting people, including the reader, in their proper evolutionary framework. Humans are conceives as intimately related to the man-apes. The opening of the book implicitly connects us back with beings whom we would most likely consider animals.
The activities by the monolith offer a particularly interesting bit of science fiction, while raising many questions. The intelligent beings who begin to control the man-apes teach them to do various things, like tying knots and hunting. Still, not all man-apes can be taught—only certain ones are capable of learning, of being improved. This whole incident presents a new take on evolution, one in which an external entity intervenes to push forward human evolution. At the same time, this process retains many of the features of evolution—the man-apes are not extended beyond their natural limitations—nothing supernatural is occurring; they simply learn to use their natural endowment in new ways.
This whole episode raises a very interesting, counterfactual question. At this point in the book, the man-apes are starving. We wonder if they would have learned to hunt if the monolith never descended and the man-apes were never taught to hunt. Furthermore, the narrator expands on the significance to the man-apes of learning to hunt. Since they could hunt, they were no longer constantly concerned with the origin of their next meal and they had time for leisure and "the first rudiments of thought." If the man apes had never been taught by the monolith to hunt, would these behaviors have ever developed? Would humans have ever evolved or would the man apes have simply died out or produced a much less impressive evolutionary line?
At the end of part one the narrator comments, "as long as [nuclear weapons] existed, [man] was living on borrowed time." This foreboding sentence serves a number of purposes. First, it introduces to the narrative the notion that technology could pose a problem for people, foreshadowing the later developments of the book, in which technology gets beyond human control. Second, this statement begins to develop one of the major themes of the book-the potential destructive power of technology. While this point has become trite in contemporary society, there was a strong attitude, prevalent in the decade before 2001 was written, that developing technology would lead inexorably toward human progress.