People with a high IQ, no matter from where, are an experiment of the evolution. It seems they are not aggressive enough to replace the average intelligent. It may be true that some degree of ignorance is required to survive in this worlds dogmata.
Depending on your point of view: Since 'smart'/educated people tend to have significantly less kids than those at the shallow end of the gene pool, evolution 'favors' low IQ.
(Of course one shouldn't anthropomorphize evolution -- it hates that)