This is quite an interesting follow-on. Not only do we see more of the dynamic of these creatures development (much is made of their territorial instincts) and breeding practices, but we also get a look at the intelligence behind their evolution to begin with. It's not the sort of earth-shattering read Sawyer's done before (even if there is some chipping away at rocks) but it's spinning out a good, solid story with a profoundly interesting species, the like of which have rarely been done as well in the genre.