this is a very interesting theory.

economic inequality leads to shorter life expectancy because being at the bottom of the social pile puts people under prolonged stress.

Depends on how one measures intelligence.

In my field, sociology, Kanazawa has published quite a few papers that have been accused of being sloppy in argumentation and/or methods. I would double, triple-check any conclusions he makes.

To me the out come seems to reflect a intuitive state of being. The simple fact that such economic conditions exist in certain places without revolution suggest something about the intelligence of the situation. I've seen this situation here in USA where social bias has been used to avoid the stigma of being on the bottom of the social pile.

As we all know anyone that is smart is rich.

Despite my smart-assed comment above, interesting finding. This will be interesting to follow.