M. C. A. Hogarth’s The Worth of a Shell (self-published) is a complex, serious, well-thought-out extrapolation of the consequences of alien sexual biology marred only by the fact that one of its central premises is not at all credible.
The Jokka are presented as a humanoid species with three sexes; males, females, and neuters. There’s a tragedy built into Jokka physiology; under stress, the females often have strokes that decrease their intelligence. Giving birth induces such stress so reliably that after multiple pregnancies they generally become mindless animals who have to be strapped into a mating harness.
This novel tells of a disgraced neuter who finds renewed meaning in his life by becoming the protector of a female who rejects breeding because she doesn’t want to lose her curiosity and self-awareness. They seek the Birthwell, the legendary origin-point of the Jokka, where she suspects there might be an answer to the Jokka tragedy.
Much of this is well executed. Hogarth has invented plausible specializations for each of the three Jokka sexes and worked out what the resulting dominant social pattern would be like in both logical and evocative detail. Her exploration of the character psychologies arising from these circumstances is equally thoughtful and convincing; she does a particularly good job on her neuter viewpoint character. It is really too bad that Hogarth has screwed up something so basic in her worldbuilding that the whole edifice collapses in a heap.
No, it isn’t the trisexuality, in itself. It is true that premise is almost certainly impossible for a species that isn’t eusocial, like ants or meerkats; the bioenergetics of this have been investigated in some detail. But we can let that slide under the One-McGuffin Rule (a work of SF is allowed one impossible or highly implausible premise as long as the consequences are worked out consistently, and FTL doesn’t count).
The real problem here is the second half – most females going non-sophont after a few births. It’s the “most” that’s the problem here. If this disadvantage were wired so deeply into the Jokka genome that there was effectively no differential across germlines it might be stable. But explicitly it is not; for a few prized females (no one can predict which) the decline is slowed or halted.
This difference is not stable under selection. Remaining sophont in order to care for and advance the interests of your offspring is such a huge reproductive advantage that the alleles preventing the stroke vulnerability should have been strongly selected for in the Jokkas’ evolutionary past, and birth-related strokes should never have had anywhere above about 1% incidence.
The author’s apparent failure to even realize this problem is a crash landing that makes this novel a sad failure as SF. Doubly unfortunate because I can think of a couple of different fixes for it that would have had minimal impact on what the author apparently wanted to do.
Note for those unfamiliar with genre forms: it is allowed for Ms. Hogarth to have an explanation in mind that she has not revealed, but respect for her readers’ ability to play the game requires that she drop a clue to the explanation, or at least signal that she knows it’s a continuity problem that has to be resolved.
Further warning: this is another one of those first-of-a-sequence books that is not so labeled and doesn’t warn you that it ends without resolution. Turns out this may only be true of the ARC; the Amazon listing describes it as first of a series.