Take a second and think of your favorite song. Is it James Blunt's "You're beautiful"? Or maybe Jason Mraz's "I'm Yours"? Whatever tune you're thinking of, if it's a pop hit released in the past 40 years, chances are good it's made up of chords with one extremely popular trait: consonance.



Our love for consonant intervals is well documented. Scientists and mathematicians at least as far back as Pythagoras have observed that certain intervals, like the octave, are mathematically perfect. In the West, those intervals today are known as consonant, and are widely considered more pleasant to the ear than their less than perfect peers: dissonant intervals.

For years, scientists thought these distinct interval preferences were hardwired into our biology; in other words, that our brains are wired to prefer one sound over another — nature over nurture, if you will. But a new study seems to squash that theory. The results, published recently in the journal Nature, suggest it is not biology that dictates our musical tastes, but rather hundreds of years' of learned behavior.

"This raises the possibility that it might be possible to develop the opposite preference given enough exposure to dissonant music," says Josh McDermott, an author of the study and assistant professor at the Massachusetts Institute of Technology. "Though that has yet to be demonstrated." He explains more in the video below.

But let's back up. What is the difference between consonant and dissonant intervals? Time for a quick music lesson. Consonant intervals are generally going to sound brighter and feel more final. For example, the main interval in "Twinkle, Twinkle, Little Star" is a perfect 5th, and is equal to three whole tones and one half tone. Dissonant intervals, on the other hand, tend to sound harsh and unfinished. The most glaring example is a tritone, like the one in The Simpsons theme song, and is equal to three whole tones.

Researchers set out to discover whether people everywhere prefer consonant intervals to dissonant ones. A few years ago they started testing the musical preferences of members of a remote Amazonian society called Tsimane. Its residents don't have electricity or tap water, and the only way to get to the town is by canoe. This meant it was unlikely these people had been influenced by Western music, which made them excellent subjects for the study.

The scientists played a randomized set of intervals to more than 100 of the tribe's residents and asked them to rate the pleasantness of each. "When we played them consonant and dissonant chords, they said they're both equally pleasant," explains Ricardo Godoy, another author of the study and professor of international development at Brandeis. "That was surprising."

Surprising, because when the team administered the same test to college students back in the U.S., the results were drastically different. The American students overwhelmingly preferred consonant intervals to dissonant ones.

The researchers also tested residents of the capital of Bolivia and those in a Bolivian town near the Tsimane, who had moderate exposure to Western music. Fascinatingly, their preference for consonant intervals fell somewhere in between that of the college students and that the tribe members.

When the tests were finished, the researchers were left with results that contradict what scientists have theorized for many years. The preference for consonant intervals to dissonant ones, it seems, is not universal. That means it's possible we humans are not biologically programmed to prefer certain sounds, but rather our musical tastes have been learned over time.

But what sparked this learning? It may have been our early instruments, says Brian Moore, an auditory perception professor at the University of Cambridge. It was much easier to play consonant intervals on simple instruments like the pipes, so those sounds were likely what we were exposed to the most, and therefore developed a preference for.

That doesn't mean the West is completely void of dissonant-filled music. A lot of jazz and classical music composers experiment with these types of sounds and have been doing so for decades. For example, famed 20th century classical composer Béla Bartók is known for including a wide array of dissonant intervals in his music.

These new findings could encourage composers to keep experimenting with dissonant intervals, says Moore, and maybe we'll start to learn to truly love those dark tones. "I think it will shake up those people who believe that these are sort of hardwired preferences," Moore says. "It may open the grounds for more novel compositions." Meanwhile, next time you can't help singing along to your favorite song on the radio, now you'll understand a little bit more about why.