When I think about science fiction, the best example is the "Time Machine" by H.G wells.  I saw a movie version of it not so long ago.  Perhaps the movie is a bit different from the original book so don't penalize me if I got some things distorted from the original.  The initial word that flashes through my mind is "awesome".  Awesome even though the developments were extremely scary.  As he goes more and more into the future, he arrives in a destroyed future.  A future where the "warlocks" (deformed mutations of our former form), torment the humanity that still lives above ground.  Major events in the earth divided the human races in two species.  One that was devoid of pigment and that was forced to live underground.  A future where humans are eaten by creatures is certainly not one to look forward to.  However, it does show us that humanity is fragile thing.  And if Darwin is correct, then it is theoretically possible that the human species could separate into two different species.  Given enough time in different envirements, the two sects of people could evolve differently.  I think most people who watch the film and believe in Darwin's findings would agree with me.  Insterestingly enough, I personally do find this type of film much more entertaining than the segment we watched on Darwin.  People are far more interested in watching humanity spilt into two species than to dwell on Darwin's ethical dilema.  It's just the society we live in.  Science fiction sells because it takes us to "la la land".  Science itself does too, but not as much I guess.