Idiocracy: Some Peeples Thinks It's A Jook
If a population has a mean IQ below 90, it is unable to maintain a modern high tech infrastructure. Why? Because a mean IQ below 90 means that there are insufficient numbers of people high enough on the Bell Curve to be knowledgeable and competent physicians, engineers, nurses, accountants, teachers, attorneys, judges, scientists, etc. etc. The mean IQ of the world population currently stands at 90, but is projected to drop to 84 over the next several decades.
As mean IQ goes down, societal competency goes down, and corruption goes way up (Russia being a major outlier). It becomes impossible to maintain the machinery of society, until the entire world looks like Zimbabwe or Nicaragua.
Our friend Kevin McGrew of Intelligence Testing blog offers the above educational slideshow for background information on what may be rapidly growing numbers of the Forrest Gump segment of society.