Posthumanity was the term used to describe the human race after the destruction of the Earth.
Some ten million years after the 21st century, Sol went supernova. This deprived humanity of their common cultural reference point. Thus since they were post-Earth, they were posthuman, forming what became known as the posthuman hegemony.
Two distinct political viewpoints resulted. One, the Arcadians, considered themselves the preservers of the old Earth's ways. They recreated Earth on 28,000 Earth-like display of which was Siloportem. (PROSE: The Book of the War)
Posthuman races included the pilots, (PROSE: The Book of the War, Newtons Sleep) the Yesodites, (PROSE: A Hundred Words from a Civil War) and Quire. (PROSE: Work in Progress, Tribal Reservations, Quire as Folk, Intermissions, Future Relations)