I enjoyed Asimov's novella Ugly Little boy & so I tried the novel. The authors ,I'm guessing, did an intersting approach to collaboration. Rather than trying to merge their different styles (something that would've been very difficult) they ,once again I'm presuming, wrote 2 stories & connected them. The Neanderthal story of where the child came from is pure silverberg, the future tale of where the boy ended up is a great deal like the original novella so it's pure Asimov. This works because asimov's original story was about the child being "a fish out of water" & silverberg does a good job of showing the "waters" he came from. Therefore the contrasting styles are almost necessary. In novel form it becomes a story of a child going from a Silverbergian world (Which in my experience means beautiful, passionate, melancholy, dangerous, & in this case primitive) to an asimovean one (Which I'm more experienced with: rational, shiny, techy, & in this case a bit cold). This approach makes the contrast between the primitive & the futuristic more real. It will please fans of prehistoric romance & futuristic fiction. Also it's just a great story about being thrust to a place where you don't fit in, but where you find people to care about anyway. Recommended & I wouldn't mind other collaborations using this technique. If ,of course, they really did use the technique I described. I'm almost certain they did, however.