Music theory is an entirely different animal that art or music appreciation. In the appreciation classes, you look at or listen to, then discuss, and maybe write a paper or 2. Music theory requires one to actually compose sections of, or entire, pieces of music using the common era rules of voice leading, harmony and the like. Don't know where you went to school, but theory was no easy A, and I was highly motivated to learn the material (to this day, 25+ years after graduating from college, I still perform).
But you can say music has evolved. In theory.
Wish I could say this....
Sniff.....