Here's a simple theoretical situation. A brilliant mathematician with very high IQ crashes in the jungle, but is unhurt.

Not far from the crash site, there's a tribesman who lived in the jungle all his life. He doesn't know how to read or write.

The jungle is filled with predators, spiders and snakes. The sun is setting, the night starts soon.

Who has bigger chances of surviving ? I guess most people would bet on the tribesman. Why does nature select the person who would most likely score lower on the IQ score ?

The point is - intelligence is contextual and circumstantial. It's not one number, like width or length. Not sure why people still try to squeeze some sort of conclusion from it..

1. Comparing the bottom 2.5% to the top 2.5% is a vast range and not really applicable to just about anybody who's able to read. So the effect may be real but irrelevant for 95%+ of humanity.

2. It doesn't look like they controlled the expected longevity to the actual longevity and instead compared it to projected longevity. It seems flawed.

0. Since it comes from sociology type research, odds are that it is pure bunk. I would like to see it replicated before it actually got any air time in any serious conversation.

(Yes, I know I have trouble counting but the last one is applicable to almost all modern research)