I just finished reading Frank M. Robinson's novel Waiting. The book had a very good premise, another species in the genus Homo has been hiding amongst us for the last 35,000 years waiting for the opportunity to take over the earth. One of them one's found out by a doctor and now the "Old People" are killing everyone who may know about them.
The first 2/3 of the book was much better than the last 1/3. I liked the concepts in the book and found the book somewhat interesting. The book had a strong save the environment message through out it, which did not bother me. The best parts were the flashbacks that showed us the racial memories of the others, namely how the lived and how humans had butchered most of them so long ago. The book had some characterization problems namely how the main character Artie acted and how the "Old People" were portrayed. I figured out that he was married to one of the "Old People" fairly quickly and did not like the ending very much at all.
By far the best thing in this book was the speculation on the other species. It is not a stretch of the imagination to envision Homo Sapiens having wiped out the other humanoids 35,000 years ago seeing how humanity has wiped out a number of species and even commits genocide on other humans (Mayans, Armenians, Jews, etc.). The other species in the book managed to survive because they looked enough human to blend in which is fairly believable seeing how much variation there is amongst humans (Ex. Eskimo, Pygmies, Europeans all look fairly different) and they killed their own offspring that looked less human. Palaeontologists have found bones of Neanderthals in Levant that could probably pass for humans fairly easily. Even without blending in like in the book it is possible that we may have another species of humanoids living with man on the Earth right now, Homo floresiensis (more commonly called hobbit) lived amongst humans as recently as 13,000 years ago and there have been legends and myths about them amongst modern people of the island Flores.
The "Old People" are descendants of a species no longer around just like we are just took a slightly different evolutionary path. In the book the main difference is that Humans developed speech, art, and better tools much better than the other species who was partially telepathic capable of sending pictures to one another an ability according to the book that humans also have as babies but lose as they begin talking more. In the book the other species is very close genetically to humans close enough to interbreed successfully though the offspring are sterile same as how Horses and Donkeys can breed to create mules. The problem I have with that aspect of the book is that in the end the other species wins because an airborne virus is going to kill off the humans one that they are immune to. The other species is genetically similar enough to humans to interbreed so almost all diseases humans are susceptible to they should be as well. Even saying they are immune doesn't mean that they will stay that way seeing how virus's mutate and jump species that are far more drastically different than the species portrayed in the book.