If you haven't seen this movie, you should add it to your Netflix list. Its a slightly disturbing look at what the world might look like in 500 years. Written by Mike Judge , of Beavis and Butthead fame, its not an Oscar contender , but its very funny, in a thought provoking way.
The premise of the movie is in the short clip above. The more intelligent people, wait to have kids, the less intelligent people breed like rabbits. Over 500 years the average intelligence dropped to the point, where people can't figure out how to get rid of garbage, or grow plants.
The entire Synopis is on Wikipedia , but do yourself a favor and watch it.