It's all bullshit.
So someone tests well..... big whooooooop.
Drop that same someone in a dessert. 1000 miles from nowhere, and I guarantee he's a dead man(woman, er person)
Drop the same "mentally handicap" that grew up in the dessert, and he/she makes it out just fine.
It's all relative. So a genius grows up in the ghetto. He's still an idiot according to the tests because the opportunity wasn't affordable.
I'm speaking (literally typing) from experience on this one. Will I live longer than most? Probably not. I pride myself on realism. I don't want to live longer. The world isn't that great. Which of us genius' here are going to leave a REAL mark on society/civilization?
I'm a damned good carpenter. I taught Calculus in high school. I have no education past high school. I actually tested out of college, but never had college credit (BA degree). Without funding there is no formal recognition of talent.
The best IQ test I took was an internet test. After an hour of testing (I was younger and wanting to prove my smarts) I noticed patterns. I figured similar questions were being asked for consistancy in answers. I kept going. Some questions provoked thought. I got tired of taking it. When I quit the results were poor. Said something of being an idiot for wasting so much time. I had to laugh.
Another IQ test that really got me laughing, which I didn't take, the tester asked my friend's younger brother: "Say as many words in a minute as you can think of". He started counting. Pure genius..... hundreds of words in sixty seconds.
Education is great, but not the end all be all of success. IQ test measure, in most cases, education...... at least from my seat.