College Majors

This month little brother Abe is starting school near me. He postponed college for a year or two while saving cash for tuition (all of us kids have done this and therefore started college late) and deciding on a major. What to major in is quite the question: Abe loves art, drama, music, and languages, but he also excels in the sciences. He considered artistic versus scientific (knowing Abe, he made a pros and cons list), and this Spring he was leaning towards a PA (physician's assistant) degree. I was hesitant to give approval to this choice - I think there is value to a PA degree, but it's a limited field. However, Abe changed his mind and is going whole hog medical school. At least, so he says for now.
I was kind of in Abe's situation when I started college back in 2001*. I went to school on an art scholarship, and eight years later I was a pharmacist! We both are mostly right brain in interests and abilities, but can do left brain tasks as well. I started out in art, but quickly realized that I could do well enough in more scientific areas to pursue any number of careers. I changed my major from studio art to biology after two years, and went on to pharmacy school. Abe's major is biology for now, but I'm wondering if he'll change his mind once he starts classes.
From an unofficial poll, I gather that a lot of students change majors during college. Did you? Was it a drastic change? Did you lose credit hours? After two years of art classes my only pre-pharmacy requirement that I had met was freshman English!
* But not really. Abe is all brilliant and stuff and taught himself Mandarin. And he runs a 4:19 mile. So I don't really hold a candle to Abe. Ah, little brothers! First they get all tall and bigger than you, then they whoop your academic record!