Lichtenberg's Sime~Gen series involves a distant future where human beings have evolved into two races, with a predator-prey relationship.
New York Times critic Gerald Jonas described Sime~Gen collection as combining "qualities of both porn and the soaps ... because they deal obsessively with the physical union between the two races". The physical union between Sime and Gen, which is not actually sexual, provides the Sime with a life-giving substance known as
selyn, produced only within a Gen's body. The Sime~Gen series began with Lichtenberg's
Operation High Time, a short story published in 1969. It followed with her first novel in 1974,
House of Zeor. As Lichtenberg continued work on the Sime~Gen series in the 1970s, science fiction writers Marion Zimmer Bradley and
Hal Clement provided encouragement and mentoring, teaching her more of the "craft and trade of writing". She also became involved with writing partner Jean Lorrah, who co-authored
First Channel (1980) with Lichtenberg. In the 1970s, dedicated fans of this series created the
fanzine A Companion in Zeor, first published in June 1978 by Karen MacLeod. == Bibliography ==