Fans of pop music know that it has undergone some pretty dramatic changes in recent decades, and one musical genre seems to be driving this musical evolution more than others.
An exhaustive new analysis of chart-topping songs from 1960 to 2010 shows that hip hop had a bigger effect on pop music than any other pop genre--and that includes the music of the so-called "British Invasion" by The Beatles and other groups in the mid-1960s.
That's right, "hip hop, the hippie, the hippie, to the hip, hip hop, and you don't stop," as Sugarhill Gang puts it.
"I was surprised quite how massive a change rap and hip hop introduced into the charts, and that it happened nearly 10 years after Grandmaster Flash’s 1982 hit single 'The Message,'" study co-author Dr. Matthias Mauch, a lecturer in the field of music informatics at Queen Mary University of London, told The Huffington Post in an email. "Hip hop tracks really have a different 'anatomy' -- we measure more speech-like sounds, and almost completely devoid of chords, the cornerstone of basically all other genres that previously entered the charts."
17,000 songs. For the study, evolutionary biologists and computer scientists analyzed more than 17,000 songs featured on the U.S. Billboard Hot 100 charts -- which Mauch called the "fossil record" of popular music. They took a close look at trends in the songs' harmonic and timbral properties, among other musical properties.
The researchers then used these properties to build an audio-based classification system of the various musical styles. Using the system, they looked at the diversity of the songs during various eras and at how trends changed across the years.
What did the researchers find? Though music evolved continually, the researchers identified three stylistic "revolutions" during which the change from one year to the next was unusually large: Around 1964 (the era of British bands), 1983 (the rock era) and 1991 (the era of mainstream hip hop).
"The third revolution is the biggest," Mauch told BBC News. "This is so prominent in our analysis, because we looked at harmony -- and rap and hip hop don't use a lot of harmony. The emphasis is on speech sounds and rhythm... This was a real revolution: suddenly it was possible that you had a pop song without harmony."
When it came to diversity of songs in terms of style and other musical properties, 1986 was the least diverse -- but in the years following, diversity went back up.
A lot like biology. Oddly enough, these revolutions in pop music mirror a biological phenomenon known as punctuated equilibrium, in which long stretches of gradual change in species are "punctuated" by periods of rapid change, Science magazine reported.
"It’s interesting to compare this behavior of the charts to biology," Mauch said in the email. "Slow evolution patterns with few fast changes is what evolutionary biologists have also observed in the world of living organisms."
Now that the researchers have discovered how pop music has changed scientifically in recent years, they next want to analyze why music has changed.
"Culture is not anymore about music critics and art critics telling us the way it was, it's going to be about scientists telling us about what the actual patterns are," Dr. Armand Leroi, professor of evolutionary developmental biology at Imperial College in London and the study's senior author, told the AFP. "From here, we want to understand the forces that have actually shaped things."
The study was published in the journal Royal Society Open Science on May 6, 2015.