How can studying music give us an insight into social change throughout history?

Throughout history, the kind of music people compose, perform and listen to is intrinsically linked to the kinds of lives these people lived. The sheer fact that not much of popular/folk music pre-1850 has been preserved shows the powers of the aristocracy as well as the contrast of eduction level between various classes, as only the rich and well-educated managed to preserve their music through the act of notation. 
Moreover, studying the evolution of jazz in America from swing tunes to fast bebop shows the desire of oppressed black musicians to be recognised for their technical artistry, having their music been mostly relegated to background music for rich white patrons. Thus by trying to understand the background of the music and study the wider social context, music offers a fantastic insight into what it was like to live during that time.