Marissa Mayer didn't become a doctor because her state school friends were learning the same things

Yahoo CEO Marissa Mayer started out as a pre-med student at Stanford, but after her freshman year, she completely reversed course.

Why? You might think it was because she didn't like her classes, but that actually wasn't the case, she told Bloomberg. She did it because she was learning the same things as her friends at state school.

"After my freshman year, I went back to Wausau [her hometown in Wisconsin], and I realized that I was learning all the same things that all my friends who went to the University of Wisconsin-Madison were learning," she told Bloomberg. "We were all memorizing the same flashcards and had the same carbon atoms and molecules. I'm doing something much more expensive, so how can I really get the most out of Stanford?"

When she returned for her sophomore year, she switched majors to symbolic systems ("You look at how people learn, how people reason, and ask a computer to do the same things," she said). That put her on a path that would lead her through Google and eventually to become Yahoo's CEO.

But it still seems like a pretty strange reason to switch majors.