December 1, 2021

I, Science

The science magazine of Imperial College

Anne Petzold finds out what happens when an evolutionary biologist teams up with a music informaticist

The biosphere of pop music

taylor swift shutterstock_185452082When asked to define the nature of time, Saint Augustine famously confessed that “If no-one asks me, I know: if I wish to explain it to one that asketh, I know not”. The same may be said of pop music.

Whatever pop music exactly is, it seems a fair bet to say that whatever is high up on the US billboard charts is certainly popular music. The Billboard Hot 100 represents a record chart of singles sold in the US every week, thereby reflecting pop music tastes for almost 60 years now.

Certainly, tastes change – but how much, and when? Evolutionary biologist Armand Leroi from Imperial College and Matthias Mauch from Queen Mary University teamed up to analyse changes in pop music tastes as they would an evolving ecosystem.

A total of 17, 000 songs populated this biosphere, all of which were classified into species (genres) based on tags by users, and dissected into their component parts to identify their major features and how these changed over time.

The pop music pub quiz

arctic monkeys shutterstock_246841651The study itself is a little treasure trove of fun facts about pop music. One of the most stubborn and abundant features of pop songs of the last 60 years is the presence of major chords only, without variation, as in Bill Haley’s Rock around the Clock (1954) or in ‘505’ by the Arctic Monkeys (2007).

We have to search for transient features, however, to find changes in pop music tastes. Among those, the dominant 7th chords that are often used in jazz and blues to create the dissonant, ‘dirty’ color in songs like Nat King Cole’s When I Fall in Love (1956) and Ella Fitzgerald’s Cry Me a River (1975) have been continuously declining since the 1960’s, marking the death of jazz and blues in popular music.

Even more interesting are features that emerge, so to speak, completely out of the blue: essentially no pop song was viable without proper chords until the end of the 1980’s, when fledgling flocks of pop songs foregoing chords marked the rise of hip hop and rap (for example Busta Rhymes and Snoop Dogg) in the 1990’s.

The evolution of different species of pop music

Mauch F3.large
Evolution of musical styles in the Billboard Hot 100 (from Mauch et al. 2015)

For the pub quiz record: whenever someone sniffs at you for not being able to tell apart heartland rock from roots rock, and grunge from indipop, retort that, according to science, there are really only 13 pop music styles that can be objectively discriminated based on their song features with the power of statistical modeling.

Considering the frequency of the different style species of pop music in the last 60-odd years, we must conclude that some died out in the biosphere of pop (jazz, blues, funk, R’n’B) while others experience revivals (rock) and others emerged in the last decades only (markedly the species encompassing hip hop/rap/house).

So is it all going to sound the same, eventually?

If you care about pop music, take home at least one consoling message: the often-lamented homogenization of music is an illusion, and the evolution of pop music is not converging on a single Taylor Swift tune.

In fact, diversity in the realm of pop music does not generally decline over time. There are periods of stasis, however, due to the “the rise and fall of particular ways of making music”, such as the introduction of synthesizers in the 1980’s.

A revolutionary history of pop music

snoop dogg shutterstock_81636316Periods, or ‘eras’, of a particular taste last until they are shaken up by musical ‘revolutions’. But which are the most revolutionary years of pop music? The year when The Beatles hit the US music market perhaps? Or the debut of The Rolling Stones?

– – – Spoiler alert! – – –

Nice try, but far off:  the biggest revolution occurred when Rap hit US mainstream music in 1991. The emergence of Rock’n’Roll sparked a smaller revolution in 1964, and the British invasion was carried on the heat wave of another small revolution in 1983, which coincided with the introduction of synthesizers rather than with the import of the Beatles.

Anne Petzold is a second year PhD student studying neuroscience

Images: Taylor Swift in concert (Everett Collection; Shutterstock); Musical genres (Mauch et al. 2015; Creative Commons); Arctic Monkeys in concert (Astrobobo; Shutterstock); Snoop Dogg in concert (Mat Hayward; Shutterstock) 

Citation: Mauch, M. et al. (2015) The evolution of popular music: USA 1960–2010 Royal Society Open Science DOI: 10.1098/rsos.150081