How Does Music Evolve? Modern Pop Hits Are Happier, More Danceable

Taylor Swift knows a lot about what makes a song a hit—you could even argue she's recorded a hit about it. "But I keep cruising, can't stop won't stop moving, it's like I got this music in my mind saying it's gonna be all right," she sings in the dance-packed video to "Shake It Off."

It's not quite as simple as just penning a song that makes its listener want to get up and dance, but it turns out that between 1985 and 2015, hit songs were significantly more danceable than songs that didn't top the charts. That's according to a new study published in the journal Royal Society Open Science, which used math to pin down what has made hit songs successful.

The project was inspired by an evolutionary perspective on music. "I was listening to the sound of songs that my teenage daughter's listening to, and I found that they're very different from what I used to listen to when I was her age," co-author Natalia Komarova, a mathematician at the University of California Irvine who focuses on life science, told Newsweek. "Clearly, music is evolving."

Read more: Proof of Evolution? Birds of Prey Avoid Extinction by Growing Longer Beaks in Just 10 Years

Komarova and her co-authors wanted to figure out what factors drove that evolution. They turned to a large database in which volunteers characterized individual songs according to a dozen different characteristics. Danceability was one of those—in 2014, "Shake It Off" was joined by songs like "Chandelier" by Sia and Meghan Trainer's "All About That Bass" showed high levels of danceability. Other traits included happiness, electronic, instrumental and having a male vocalist.

Over the three decades, Komarova and her co-authors noted that songs have become less aggressive, less bright and more atonal. They've also become much less likely to be sung by a man.

Then, the team identified songs that hit the top 100 chart in the U.K. to see if anything set them apart from less successful contenders. In addition to a high danceability rating, hits tended to be less sad and less instrumental.

"They really behave like different biological species," Komarova said. "This is statistically significant, it's a real mathematical result."

Taylor Swift collected eight Billboard Music Awards in 2015, including for her hit song 'Shake It Off.' Jason Merritt/Getty Images

Finally, the researchers asked whether they could predict which songs would become hits based on the characteristics of the music itself. Komarova and team used their mathematical finding on half a million songs.

Komarova said she was surprised to see so much of a song's success or failure could be chalked up to its musical qualities—the characteristics the team incorporated into the algorithm let them guess with 75 percent accuracy.

This is good news for music lovers—success isn't just about having a superstar artist or pouring lots of money into marketing. "I think that's actually a very optimistic finding," she said. "Music matters."