Shift Toward Minor Key

Pop Music Study Shows Shift Toward Minor Key Melodies Since 1960.

It also shows a slowing of tempo, increasing length, and more juxtaposition of positive lyrics over minor keys or introspective/negative lyrics over major keys.

The lyrical content was also studied and shows evidence of the perceived change in lyrics from 1990-present, showing more personal, confrontational, and yes violent lyrics in the last 25 years.

Interesting stuff.