I'd argue that capitalism selects not only for certain types of brains (in a sort of accelerated natural selection geared towards intellectual ability), but for certain memes as well. It selects for "social memes" that determine corporate culture, which contributes largely to whether a company succeeds or not. It also selects for more "ideological memes" that serve as the basis for the company itself.

A company's success is the result of a meme (or set of memes) the founder created (or borrowed) and convinced others to buy into. Others only buy into the meme if they believe it would be beneficial to themselves as well. Thus the system as a whole selects for memes that provide high benefit to society.