This site gives the Cox I.Q. numbers for historical figures. The summary is :
Philosophers (22) average IQ 160; Scientists (39) 159; Fiction writers (53) 152; Statesmen (43) 150; Musicians (11) 149; Artists (13) 153; Soldiers (27) 136.
I personally don't give much weight to I.Q. I also have a low opinion of most philosophy. But one thing I think is true is most "name" philosophers were very smart people. I also think the questions that concern philosophers are important and that most people think about them in one way or another.
Or put another way, never underestimate the enemy.