This is Scientific American 60 Second Science.

I'm Christopher in Dargyatta.

Got a minute?

Flip through Rolling Stone and you'll read about a lot of revolutions in popular music.

Rock and roll in punk, disco and new wave. But for Matius Mao, an engineer

at Queen Mary University of London, the qualitative analysis of musical evolution, the music critics take, left him wondering.

You know, is there some way in which we can take this kind of pub conversation and make it a more quantifiable.

So he and his colleagues analyze fragments from more than 17,000 songs on the Billboard Hot 100,

from 1960 to 2010.

They process the audio to extract information about timbrel and harmonic qualities, tagging

the files for attributes like orchestra harmonic, or calm quiet mellow.

Then they use those tags, which they compare to a musical fossil record,

to tease out trends about musical evolution over time.

Turns out from 1960 to 2009,

the dominant seventh chord

all but disappeared

in what they call the death of blues and jazz on the pop charts.

But as dominant seventh faded, the minor seventh came into its own.

More than doubling in frequency between 1967 and 77.

We can really see the influx of funk, which is then turning into disco.

But next, as you know, came the 80s.

Dominated by a rise in musical tags like Percussive, and guitar aggressive.

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