The g that shows up when doing factor analysis on intelligence test results is not necessarily the same concept we all have of innate, immutable intelligence. There are good reasons to believe it's not the same thing at all -- g is mutable, somewhat heritable, and quite variable between different cultures and countries. It's a broad correlation; it doesn't correspond to any particular fundamental brain mechanism that would tell us useful things about biology.
http://cscs.umich.edu/~crshalizi/weblog/523.html
The g that shows up when doing factor analysis on intelligence test results is not necessarily the same concept we all have of innate, immutable intelligence. There are good reasons to believe it's not the same thing at all -- g is mutable, somewhat heritable, and quite variable between different cultures and countries. It's a broad correlation; it doesn't correspond to any particular fundamental brain mechanism that would tell us useful things about biology.