Robert J. Sawyer
Hominids is a science fiction novel -- perhaps best termed an anthropological SF novel, or perhaps an alternate history novel. It is also close to being hard SF, although it slips a bit at times.
The story alternates between two worlds; modern-day Earth, and an alternate version of Earth on which H. Sapiens went extinct and Neanderthals became the dominant species. On both Earths delicate scientific experiments are taking place in a nickel mine two kilometers beneath Ontario -- which is not a coincidence. On both Earths, the deep mines protect the experiments from cosmic radiation, and because the mineral deposits were created by the impact of a large asteroid millions of years ago, the background radiation present in most mines are not a problem. While our Earth is simply trying to detect neutrinos -- apparently harmless research -- the Neanderthals are working on developing a quantum computer. And when the computer accesses parallel universes to complete its calculations, it is apparently possible for it to shift a human into one of those parallel universes. Resulting in a Neanderthal physicist appearing suddenly in the middle of the heavy water tank used in the H. Sapiens' neutrino experiment.
In large part this is a story of culture shock and imagining the way things might have been -- and for the most part this is done very well. Sawyer has done an excellent job of imagining alternative technologies and viewpoints for even the most basic activities, writing a traditional 'alien anthropology' novel about a particularly interesting non-alien species. He has put a lot of effort into considering the similarities caused by living on the same planet versus the differences caused by a different biology and timeline. He does not, unfortunately, make a strong effort to keep up the culture shock aspects throughout the story and by the middle of the novel, the Neanderthals are recognizing vocabulary and ideas that they should not have references for... but by that time, you are already hooked.
The overall story is a bit formulaic, and it has clearly been written to appeal to a wider audience than just SF fans. This is not always a bad thing, but it is not really what I look for in a SF novel. I found myself comparing it in tone and readability to The Da Vinci Code or Sphere. Fast moving, easy to read, characters no smarter or more interesting than they have to be, and predictable plot points. However, half the point of SF is the interesting ideas introduced, and by that standard this is an above-average SF novel. Unfortunately, while the parallel world and the basic science are very well done, Sawyer also goes into some ham-fisted philosophy that is embarrassingly light-weight. He also falls off of the hard science bandwagon when he starts talking about the quantum origin of conscious. But this isn't too bad, given that these are short ponderings sprinkled throughout a 400 page novel.
Sawyer made the interesting choice of having one of his characters raped. As far as I can figure, this was an attempt to add human interest to the story, but it is not a throw-away event and it is treated as well as such a event can be. I do not think that this was a good choice on his part, but as long as you are willing to accept that this is a science-fiction-slash-rape-survivor story, it is a well-written one. The rape scene is fairly graphic, although it not treated as sensationalism or violence for the sake of violence.
Overall, a good book with a very good central premise. I was somewhat disappointed with how it was developed. During the first few chapters I had thought that I had discovered a wonderful new author that would provide many exciting books to read; by the end of the book I was satisfied with the story and interested to read the sequel... but not excited to go and hunt it down Right Now.
Speaking of which... The next book is the series is titled Humans. The third and final book in the series is Hybrids. The first book is fairly self-contained, but there is still plenty of world to explore and I expect the following books to be good reading.
Shortly before publication a much shorter version of Hominids was published as a serial in four parts in Analog Science Fiction and Fact, in the January through April issues. Hominids also won the 2003 Hugo Award for Best Novel.