Here are a couple of excerpts. See the entire paper here.
Title: The Evolution of Popular Music: USA 1960-2010
[E]xamines US Billboard Hot 100 between 1960 and 2010, [u]sing Music Information Retrieval (MIR) and text-mining tools [to] analyse the musical properties of ~17,000 recordings, [aka] “the fossil record of American popular music”
[findings, proposals and, for some theorists, inconvenient truths, follow]
Some have argued that oligopoly in the media industries has caused a relentless decline in cultural diversity of new music, while others suggest that such homogenizing trends are periodically interrupted by small competitors offering novel and varied content resulting in “cycles of symbol production”. For want of data there have been few tests of either theory.
Contrary to current theories of musical evolution, then, we find no evidence for the progressive homogenisation of music in the charts and little sign of diversity cycles within the 50 year time frame of our study. Instead, the evolution of chart diversity is dominated by historically unique events: the rise and fall of particular ways of making music.
[A]lthough pop music has evolved continuously, it did so with particular rapidity during three stylistic “revolutions” around 1964, 1983 and 1991.