Using techniques normally used in evolutionary biology scientists at Imperial College and Cambridge University analysed 17,000 songs from the US Billboard charts between 1960 and 2010.
They gave each song a unique signature based on harmony and timbre and with that were able to trace the rise and fall of different types of music.
They found among other things that tunes using dominant 7th chords became rarer over time. This chord is common in blues and jazz music and reflects their decline. They also looked at “thrashing guitars” associated with rock music.
The scientists found three big changes over the 50 years they examined.
In 1964 the Beatles invasion of America; in 1983 with synth music; and in 1991 with hip-hop.
There is still a lot of diversity in music despite the decline in the 1980s when synthesiser groups like Duran Duran dominated the charts. The scientists consider that revolution the most boring and it took the hip-hop revolution to change that.
Personally I don’t buy this and would question hip-hop’s influence. But then I’m old-fashioned. I go the the R&B section of a record store still expecting to find John Lee Hooker or Howling Wolf not the pretentious urban music that goes by that label today.