It surely doesn't explain differences between similarly coloured countries. In Europe Italy seems to be the bluest and yet things are not good. Ireland is very pale yet it fared pretty well before the recession.

I would argue that in many cases wealth causes IQ and poverty takes it away. E.g. ex-ussr is rather blue for its sorry state, and I guess it would be much bluer if measured 25 years ago. Argentina is pretty blue but yet it fails to monetize that. Mongolia is very blue and it's effectively a placeholder.