The World Is More Complex, Ergo Our Brains Are
The intelligence of your average person is getting higher as the influence of modern technology, travel and cultural intergration are adding to the complexities of life.
As we develop in youth, each generation requires more understanding and a higher level of attention and retention to function normally in society.
The Brain Must Work Harder
Moore's Law dictates that every 18 months the power of a given size of computational space doubles. With this technological advancement and we must informally learn and undergo neurological preocesses that in turn advance our own understanding and cognitive abilities.
In short, more advanced technology means we must become more advanced to understand it.
...and we do.
IQ Tests Are Harder
Because we get smarter, every ten years or so IQ tests require higher results to simply be average. So if you scored 105 IQ ten years ago, getting the exact same amount of questions correct would yield you a result of 100 IQ this time.
Tests change to keep average... Well, average.
It's Kind Of Motivating
The idea that a stagnant intelligence level will actually be empirically a reducing IQ level means that it can be motivating for us to increase our cerebral pursuits as not to slip behind and fall backwards.
After all, who wants to go from above average IQ to below average?
Not any one I know.
So that is something to ponder the nest time you switch on America's Most Explosive Building Domolitions instead of Discovery channel.