Yeah, Earth isn't really isn't a thing anymore. The human race, having been exposed to other Alien races, were just too weak (i.e. pathetic) and their race just kind of started to diminish. What humans that didn't die off were captured and the females were forced to breed with other aliens, making 'humanoids' (i.e. the scum of the earth) but there can still be a full-blooded human found here and there...