A serious but distended time travel yarn featuring the proto-human, hunter-gatherer Homo habilis of two million B.C. Throughout a troubled childhood, adoptee Joshua Kampa is visited by compelling dreams of Pleistocene Africa--dreams which his researches soon confirm as authentic ""spirit-traveling"" episodes. So eventually, with help from maverick, Leakey-ish paleoanthropologist A. P. Blair and unprepossessing, obsessive physicist Woody Kaprow (who are perfecting time-travel techniques), Kampa journeys back to the Pleistocene--where he involves himself with a band of bone-wielding, hut-building, fire-less, and language-less ""habilines"" (whose social system remains vague and uncertain here). And during his winsome, rather oversentimental sojourn in prehistory, Kampa mates with Helen, an uncommonly large and advanced specimen (uniquely, she's able to adopt the missionary position): after she dies in childbirth, Kampa will return with the child to the present. Thoughtful, glum, choppy work--chapters of Kampa's biography alternate with the habiline saga--but, if less crisply vivid than Bishop's short stories, his fans (and anthropology buffs) will certainly find it worth trying.