I must admit that I'm somehwat surprised by the controversy surrounding this book. It certainly isn't as good as his other works (the New Dinosaurs, After Man and the Future is Wild) but it certainly isn't a terrible book either. It seems that most people dislike it either because it leans so heavily towards sci-fi/paranormal (mainly via psychic powers and genetic engineering) or because it degrades humankind. Honestly, if you have no problem with sci-fi influences or with a pessimistic attitude towards human nature then you probably won't be too offended by this book.
Like all of Dougal Dixon's books, it starts out with a brief history of homo sapiens and our ancestors. The short accounts of us are given in a first person fashion, departing from his other works but I didn't find them to be hard to follow. He then gives an evolutionary chart for the various species in his book. The book then starts two hundred years in the future, as a rift develops between the upper and lower class humans, and the genetically modified servants. Another century later, their descendants are examined. Then it jumps ahead to 500 years from present, when genetically modified humans are created to repopulate the earth (from which most large animals have been exterminated) and upper class humans are kept alive through machines, while lower class humans resort to communal agriculturalism. Another five hundred years and we come upon an earth on the brink of disaster, as both the high-tech mechanical societies and agricultural communities fail while the genetically modified humans in the wilderness survive.
The book keeps going showing the various twists and turns taken by the genetically modified humans, as they evolve into strange new organisms. Psychic powers, symbiosis, parasitism, aquatic lifestyles and social colonies all evolve, and vaguely humanoid creatures colonize tundras, plains, jungles and other environments. Ultimately 3 million years into the future these creatures come closer to animals like mammoths, slothes, jerboas and sabretooth tigers than humans. The book closes out at 5 million years, when the descendants of upper class humans sent to space colonies return to earth, genetically modifying and exploiting their "cousins", and ultimately laying waste to the earth. But there is still survival, and life goes on in strange new forms.
Ultimately I found this book to be an interesting concept, though not on par with his other works. Still it was a nice experiment in sci-fi for Dixon, and if you're a fan of the genere then you will probably appreciate this book. If reading this review you decide that you wouldn't like it or would find it offensive, then don't bother tracking it down. Trust me, its out of print and usually expensive to buy. Thats about the best I can say for this book. I appreciated it, but others out there might not feel the same way, so just read my review and consider whether or not it sounds like you would like it.