Ursula Le Guin (http://en.wikipedia.org/wiki/Ursula_Le_Guin) published The Left Hand of Darkness in 1969.
Her work, like a great deal of science fiction/fantasy is really about human life and human existence rather than exotic places in the Galaxy. This is the story of ‘Winter’, an Earth-like planet where the weather conditions are semi-arctic and the inhabitants are all of the same sex, which is invited to join a coalition of planets. A major theme is that of gender. Thinking person’s science fiction, this has long been hailed an influential classic of the genre.
256 pages in the Orbit paperback edition.
ISBN 978-1857230741
Ursula Le Guin