Ok, this is cool - especially if you're a science nerd like me.

A joint study from the Spanish National Research Council, The Center for Research Mathematics, and 2 Spanish Universities has been studying almost half a million pop songs from 1955-2010.  They analyzed the songs on the basis of pitch (harmonic transitions, chord structure, melodic range, tonal arrangements), timbre (sound texture, tone quality, instrument diversity, performance expression) and the intrinsic loudness of the recording (that is, the volume level applied during production, not the volume controlled by the listener).

What they found was a logarithmic and power law-driven decline in the diversity of all pitch and timbre parameters, accompanied by a simultaneous increase in the applied volume of pop recordings.  The lead investigator told Reuters: "We found evidence of a progressive homogenization of the musical discourse. In particular, we obtained numerical indicators that the diversity of transitions between note combinations - roughly speaking chords plus melodies - has consistently diminished in the last 50 years."  From their final discussion:

"Much of the gathered evidence points towards an important degree of conventionalism, in the sense of blockage or no-evolution, in the creation and production of contemporary western popular music. Thus, from a global perspective, popular music would have no clear trends and show no considerable changes in more than fifty years."

Damn!  It's a nice validation to what many of us have known all along: all of the interesting stuff comes from outside of the mainstream.  

The Reuters short version: http://ow.ly/czhf6

The full journal article, with all the data (caution: copious nerd-speak): http://ow.ly/cziCM

...IT'S TOO BAD , BECAUSE THERE WAS A TIME THAT WAS'NT TRUE. FOR ALL THE LIMP POP MUSIC OF THE 50'S AND 60'S (STILL BETTER THAN THE LIMP POP DREK OF THE 80'S AND BEYOND.) , THERE WAS STILL SOME CUTTING EDGE STUFF IN THE TOP 100 FOR YEARS. NOW , WE'RE JUST TOLD WHAT IS "CUTTING EDGE". I'M NOT TALKING JOHN CAGE OR STOCKHAUSEN , BUT , LITTLE RICHARD , LINK WRAY , JERRY LEE LEWIS , THE TRASHMEN , AND EVEN ELVIS , WE TAKE IT FOR GRANTED NOW , BUT , THAT WAS HEAVY SHIT .  THEN , OF COURSE , YOU HAD ALL THE GREAT MID-60'S "NUGGETS" ERA HITS , AND EARLY HARD ROCK , BEFORE IT GOT SOFT. EVEN THE LEGENDARY STARDUST COWBOY GOT INTO THE BOTTOM OF THE CHARTS IN 1968 , WHILE BLUE CHEER MADE IT TO THE TOP. BUT  , EVERY ERA HAD IT'S DULL ,LAME POP MUSIC , AS WE ALL KNOW.