you must not teach middle school (as i do) if you did, you'd have no problem believing that people aren't as smart as they used to be.
I teach where i went to school. Only one of the teachers that taught me still works here. I asked her to compare our generation to the current one. She said 2 things:
1. Parents now were raised by parents who were (on the whole) strict on them and expected them to study and work hard. They thought it was "unfair," so they don't "force" their kids to work as hard, hence overall lower student performance. (Same can be said for behavior as well)
2. TVs are used more as babysitters and shows like Sponge bob have little redeeming qualities for children to learn from.
Living where i did growing up, we didn't get cable till i was 12. Cartoons only came on on weekends and the only other children's programing was on PBS and it was educational. If you watched TV then, you either learned something from an educational show, or watched a more mature show that required more "adult" thinking.
So instead of kids rotting their brains to Sponge Bob, we watched Fantasy Island reruns or even Gilligan's island reruns in the afternoons. Gilligan's island was brilliant as kids programming because it stressed the importance of science in the role of the professor. It showed how people with money sought to use it for power and influence (the Howells). How a movie star was just a normal person who put on a persona to influence people (Ginger), etc...
Well, i guess that was kinda long winded huh?
Anyway, take it from a 7th grade teacher, on the whole, kids aren't as studious as previous generations were, and they have taken the concept of "work smarter, not harder" and turned it into "why work? Someone smarter will do it for me."