Yesterday’s Kin (Nancy Kress; Tachyon Publications) is a surprisingly pedestrian first-contact novel. Surprisingly because Nancy Kress has done groundbreaking SF in the past. While this novel is competently written, no new ground is being broken here.
Aliens land in New York City and announce that within a year Earth will encounter a sort of interstellar spore cloud that is likely to be infectiously lethal to humans. They ofter help with attempts to develop a cure.
Then it turns it that the aliens are human stock, transplanted to a distant K-type star 150,000 years ago. There are a handful of human with a rare haplotype that they recognize as kin. A few of these kin (including one of the major characters) attempt to assimilate themselves to the aliens’ culture.
Sadly, there isn’t as much story value as there could be here. Far too much of the novel is spent on the major characters’ rather tiresome family dramas. The resolution of the crisis is rather anticlimactic. SFnal goodness is mostly limited to clever re-use of some obscure facts about human paleontology.
On her past record, Nancy Kress might have some really thought-provoking novels in her yet. This isn’t one of them.