The intriguing what-if here: North America inhabited, not by Indians, but by ""sims,"" ancient (and, in the real world, extinct) humans of the species Homo erectus. However, Turtledove evidently is no novelist: like his debut (Agent of Byzantium, 1987), this one consists of short stories that consider the notion from broad though superficial perspectives. Sims are upright, small of stature, small-brained, and less intelligent (though not unintelligent) than modern humans. Their tools are primitive, they are unable to make fire--yet, while incapable of reading or learning a language, the sims soon learn to communicate with the early European settlers via hand signs; so they are viewed as natural slaves. However, their very existence causes differences in the way society develops over the centuries. Samuel Pepys, for instance, buying a pair of sims as slaves, is moved to postulate a theory of evolution. In America, the enslavement of blacks fails to survive its first court challenge in 1805: sims are, after all, demonstrably inferior to both whites and blacks. Later, injured trapper Henry Quick, in order to survive, must join a band of wild sims, where he comes to recognize their essential humanity notwithstanding their lack of intellect. Despite all this, though, sims remain slaves: in alternate 1988, as an AIDS epidemic looms, sims prove to be ideal experimental subjects. Mildly provocative, curious, and entertaining enough, even if the overall effect resembles a Reader's Digest version of something more substantial. Turtledove is simply too mercurial a writer to explore the idea to any truly challenging degree.