In Kurt Vonnegut's novel Galápagos we follow the destiny of the human race.  The problem with human beings, according to Vonnegut, was that their brains were too big and that this caused no end of misery.  The story is narrated over the next million years by the ghost of Leon Trout, the son of recurring Vonnegut character and science fiction author Kilgore Trout.  Repeatedly the deceased father beckons Leon to enter the blue tunnel leading into the afterlife but Leon demurs.  He stays to watch as the last colony of humans on Earth devolve into a race of seal-like creatures with small brains and a cheerful disposition.  Finally there is nothing interesting happening anymore and Leon accepts his father's invitation and leaves.

The blue tunnel of the novel suggests to me the universal unconscious longing for a return to the womb (that distantly remembered paradise) and this is paralleled by the return of human beings to the sea, untroubled by disturbingly big brains.  All problems solved.