Is pop music going slower and more sad by the minute ? Seems like it according to two behaviorists Phd from Canada !
Dr. Schellenberg and Dr von Scheve have analyzed more than a thousand US popular music hits from 1965 till 2009, looking at tempo and mode (major or minor, determined by the tonic/main chord of the song). Most of pop songs used to be in fast mode and major chord but there has been a steadily increase (they have doubled in fact) in hits being slow tempo with minor chord (usually a sad song). Plus there has been a strong increase in songs that are "emotionally ambiguous": fast tempo song in minor mode.
Not surprisingly, lyrics have taken the same way: there has been a decrease in references to social interactions and positive emotions and an increase on angry and antisocial wording! I guess, if you start scanning songs in the sixties, you'll have a good quota of social references and even politically charged songs and going thru the seventies lyrics start to be more centered on mindless fun; the eighties are quite a sad era lyric wise, the Nineties is a hymn to hedonism and since the 2000 lyrics are most often than not repeated sentences hammered...