The Beatles’ most “perfect pop song”, according to science

The middle eight in Lou Reed’s ‘Perfect Day’, the key change in The Beach Boys’ ‘God Only Knows’, the final chords in the coda of The Strokes’ ‘Under Control’, and the jazzy crescendo of Nina Simone’s ‘Sinnerman’—these are all perfect moments in music. But that appraisal is purely subjective. When science gets involved in identifying the perfect pop song from start to finish, there’s only one winner. And, unsurprisingly, it’s The Beatles behind it.

Over 60 years on from their debut single, the Fab Four ended 2023 with yet another number-one hit, closing out their discography with their 21st chart-topper, ‘Now and Then’. It’s an unrivalled feat that caught the attention of a group of German scientists with plenty of spare time. After a hefty dose of analysis, the team uncovered evidence that might explain how the Beatles managed to dominate the charts while still pushing musical boundaries.

One of the key elements of pop is catchiness, and it’s been proven by neuroscientists that one of the key elements of catchiness is… surprise. Keeping the listener on their toes in an appealing manner triggers reward pathways, so a sweet note that shocks you is akin to plunging your hand into a jacket pocket and finding a £20 note that you had previously forgotten about. When arranged correctly, this means that a sequence of surprising chords collated seamlessly provides a drip-feel of feel-good energy that keeps you hooked.

It turns out that nailing the brief is key to catchiness. A recent University of Amsterdam study named ‘Eye of the Tiger’ by Survivor the catchiest classic rock song. The cheesy 1982 anthem is now inseparable from anything remotely combative—if you’re gearing up for a blood-pumping activity, chances are it’s already playing in your head. But what about the more vague world of frivolous pop? How do you stick the landing and still surprise people when the terrain is so familiar and often far-fetched?

With this in mind, researchers at the Max Planck Institute in Germany handpicked 700 pop hits and analysed the 80,000 chord progressions contained therein. Using machine learning, they could rank the level of surprise, comparing the whole sequence note-by-note. Then, to ratify the work of the machines, they enlisted volunteers and played them the songs without melody or lyrics, just one chord followed by the next.

The value of surprise was once again proven. The volunteers found it much more pleasing when they couldn’t easily predict which chord would come next. Endorphins were released when the next chord was sweetly unexpected. So, when it comes to pleasing pop, there was one resounding winner that the scientists deemed almost “perfect”; it was, of course, the often maligned ‘Ob-La-Di, Ob-La-Da’, frequently cited as one of the worst Beatles songs. In fact, it almost broke up the band. However, with the weight of science behind him, Paul McCartney can happily rest assured that he was right to put the band through a weary session.

John Lennon once dismissed his songwriting partner’s tune as “Paul’s granny shit”. George Harrison didn’t hide his disdain either, taking a jab at it in his own song. Three months after a tense recording session for the track, he wrote in ‘Savoy Truffle’: “But what is sweet now, turns so sour / We all know Ob-La-Di, Ob-La-Da / But can you show me, where you are?” A clear dig, it made his feelings plain. To Harrison, it was a hollow tune that only served to push the band further apart.

McCartney might have called it “a very me song”, suggesting authenticity, but to the rest of the group, that ‘authenticity’ felt more like exclusion. Ironically, the tension this created—and the jilted melody it produced—may have helped the track’s success. It shows that even when the band missed, they still scored. As they fell apart personally, they somehow held it together musically. Our brains register the tension not just as the sound of a band on the brink, but as an aural thrill ride packed with stuttering surprises.

As PhD student Vincent Cheung at the institute explained: “It is fascinating that humans derive pleasure from a piece of music just by how sounds are ordered over time. Songs that we find pleasant strike a good balance between us knowing what is going to happen next and surprising us with something we did not expect.”

So, while BJ Thomas’ ‘Hooked on a Feeling’ and Genesis’ ‘Invisible Touch’ might have ranked high, none were musically more perfect than the divisive yet ultimately delightful Beatles track. Leaving McCartney with the last laugh.