Warren Douglas, in this sequel to Stepwater, offers a story even more convoluted, but just as entertaining. While he takes the structure wholesale from Vance's Alastor series, he moulds it into its own peculiar shape, less exotic, but more science-based, and more human.
Douglas posits six new human races, each built for a particular purpose and derived in part from animal genes. The races can interbreed, but produce only old humans if they do so. Part of their genetics include strong imperatives to breed within their own race. Those imperatives are a large part of what the Arbiter stories are about.
The role Douglas imagines for females is a grim one, though male roles are at times no better. Yet, the breeding issues create interesting quandaries and puzzles to solve, and females often get the upper hand somehow. Despite the grim exigencies of female life in this universe, the truth is both genders are heavily driven by instinctive or genetic needs, and their circumstances seem clearly intended as an entertaining examination of concepts, not as misogyny. Premise aside, both genders are cunning and crude, dense and deft in equal measure. It's true that old humans don't seem to have made a lot of progress over the years (there's never been a female Arbiter, but there's hope), but the rest of setup is intriguing.
Beyond the societal elements, this is a fun story of plotting, planning, and manipulation, all tied together by a basis in geology. The science is not terribly deep, but is clearly presented, and seems accurate as far as my own limited knowledge goes. The human side of the story, filtered through fard genetic constraints, is interesting, often appealing, and occasionally surprising. Douglas uses the Arbiter thread of the story as framing, and it works nicely, both as a pleasant diversion, and to remind us that there is a larger framework binding the books of the series together.
The Arbiter series was clearly intended to cover between six and eight books (one for each race, plus perhaps books for old humans and the poletzai). Douglas only published three, with one more currently looking for a publisher. The three available can be read in any sequence, or as individual stories.
I heartily recommend this book, and in fact the series. It's fun and light, and it's a nice reminder that people did still use real science in light SF not that long ago.