Science Fiction and Society

Last few weeks I have been reading Robert Heinlein’s works. One peculiar aspect of his science fiction is that in almost all of the stories the society is depicted very different from present society. To be precise male-female relationship are more often than not polygamous and polyandrous. The exact nature of relationship is ofcourse dependent on nature of society as well as male to female ratio. However assuming the male to female ratio remain equal, I believe that not only monogamy is the best way for society, but most probably it is the only stable way.