Nine workmanlike, dowdyish, often moralizing stories--mostly concerning the biological and psychological future of humankind. Veteran contributors: Ian Watson, with a rather amusing slant on the ""creation of superman"" theme; Michael Bishop, who posits the world's entire population suddenly redistributed utterly at random; Carol Emshwiller, whose ""The Start of the End of the World"" features a distinctly Lafferty-ish alien invasion; and Josephine Saxton, who chips in with ""The Snake Who Had Read Chomsky"" (perils of advanced DNA research), a novel-size idea squashed to short-story length. Among the relative newcomers: the promising Nancy Kress (books written to computerized standards of appeal); Carter Scholz, with a tangled, gloom/doom ""first alien contact"" yarn; and Michael Swanwick (grim consequences of a Three Mile Island meltdown). Clever titles, careful craftsmanship, damp-firecracker impact--a so-so installment in an increasingly unadventurous series.