I think the subject needs to put to rest. Facts are facts and many on this thread have presented enough to back this statement.......................
If you are a 1000-1100, 1100-1200 etc. etc. and you hold that number then thats where you are in the game (on this site) for example. No matter what you do for a living or who you are, If you hold that rating then thats where you are at mentaly in the game.
Most players play as a hobby, and some do advance their play. But to label what a person does for a living verses playing the game is questionable. Althought we all know that a smart person can be smart in many things and this game may not be one of them and on the other hand it may be.
So with all that said, its simple ......."Do you want to be the best? Then you should do nothing but the game from the age of the ability to make a move." Do you want to enjoy the game? Then do so. Do you want to talk about the game in measures, well that can be infinite. I am to the point of taking time off from the game and yes will be reading some things about it.
I need a sabbitcal to re-focus. Jeesh, did I just say that. But thats just me. I enjoyed the reading, and thank all who replied. My perspective has changed of the game.

johnyoudell's summary was right on. Conclusions about any study in this area are tied to the "intelligence test" used in the study. There are lots of Different tests for "intelligence," and they're all multivariate, and almost all are skewed by cultural factors. The closest to "pure" intelligence is G factor, but that alone doesn't have much predictive power.
Definition of "intelligence?" "Intelligence is what inteligence tests measure." Tautology? I'll say. ;-)