In Dunbar on Friends I wrote about the different kinds of friends. In the Savanna Theory of Happiness, people living in sparse density areas and with higher frequency interactions with close friends are happier. Satoshi Kanazawa and Norman Li leverage Dunbar to basically explain we are happier when in smaller communities because our evolution has not yet caught up to our societies. Only… More intelligent people have the capacity to thrive in more dense areas without as much time with their friends.
I find this curious because it would suggest more intelligent people are extroverted. Pro-introvert researchers claim people who avoid social interactions are the more intelligent ones.