So there's a comic book series called "Y - The Last Man" that's actually pretty related to the topics we've been discussing lately. But unlike Left Hand of Darkness, which shows us a world where the two sexes as we know them have been sort of combined, this series shows us a world where one sex just ceases to exist.

I think this is a little more formal than what others have been posting, but here it is anyway. It's somewhat an expansion of the comment I made earlier, with some more points and some textual support: