How did ‘Old Town Road’ become so popular?

Turns out, there’s a scientific explanation for the unprecedented success of the country/hip-hop mashup. Written by rapper Lil Nas X and featuring Billy Ray Cyrus, the song has spent most of this summer at the top of country music charts and the Billboard Hot 100. It was even in the No. 1 spot on the latter for a record 19 weeks. But why?

According to an AI tool created by University of Southern California researchers, it’s because the song successfully combines multiple music genres in a way that our brains find entertaining. It has the lyrics of a country song, guitar chords of rock music, but when you put it all together it also sounds like a pop song.

“The lyrics are steeped in the country genre, but the chords and the instrumentation don’t sound like country at all,” said Timothy Greer, a USC Ph.D. student in computer science who built the tool. “The algorithm highlights the complexity of music, both in terms of how the music is constructed and how it is perceived, in other words, how people process it.”