I think the article mentions "any simple way to enhance IQ" - presumably "simple" meaning that evolution would also have had an easy way to discover that simple

I think the article mentions "any simple way to enhance IQ" - presumably "simple" meaning that evolution would also have had an easy way to discover that simple way. For example if digesting a substance the body already manufactures enhances intelligence, it seems likely that it would be easy for evolution to make bodies manufacture more of that substance. I think that is especially true since many substances in the brain are really just (exchangeable?) carriers of information (I am not a medic, though).