Dynamic Duos: An AI Analysis of Artists with Individual and Collaborative Pop Success

Featuring: Billie Eilish & FINNEAS, Taylor Swift & Bon Iver, Lennon & McCartney, and Jagger & Richards

Doron Gabbay, Dr. Ari Katorza, Amir Graitzer (MyPart)

Co-writing has been a long-standing tradition in popular music. Dating back to the early twentieth century, the Tin-Pan-Alley and Broadway scenes were famously characterized by their iconic songwriter duos: Oscar Hammerstein II & Jerome Kern, George & Ira Gershwin, Rodgers & Hammerstein, and Stefan Sondheim & Leonard Bernstein.

Modern popular music, despite the celebrated romantic concept of the singer-songwriter, has also benefited from its fair share of songwriting partners (e.g. Lennon & McCartney, Jagger & Richards, Goffin & King, Bacharach & David) and songwriting teams (e.g. Holland-Dozier-Holland, the legendary Motown hit-machine).

A review of the songwriting credits for chart-topping songs in 2021 reveals a much more explicit trend. This past year’s hits feature multiple writers in unprecedented numbers. To put it simply: most pop artists do not write on their own.

The solo singer-songwriter hit has all but disappeared from pop over the past decade. For perspective, a study out of Coastal Carolina University found that between 1955 and 2009, 53% of the top Billboard hits were written by individuals while 47% were written by groups. Meanwhile, a 2020 review of data by Rolling Stone found that, “over the last decade, only 4% of the year-end Top 50 songs have come from an individual,” and that “it takes, on average, roughly five writers to write a hit song.” “Indeed, since the beginning of the 21st century, a mere 13 of the 283 songs to top the chart have just one credited writer,” according to Billboard. In 2018, Travis Scott brought this trend to new (almost absurd) heights, breaking the record for most writers credited on a single song with a whopping 30 collaborators on “Sicko Mode,” while 2021 saw Justin Bieber’s “Peaches” break a Grammy Award-record with eleven songwriters contributing to the Song Of The Year nominee.

Cynics might explain the steep rise in songwriting credits over the last decade by the multitude of copyright lawsuits and subsequent court settlements imposing the inclusion of additional writers on a particular song for fee/royalty-splitting purposes (see: “Uptown Funk"). But the truth is, crafting a pop hit is more often than not, a joint effort. For decades, there have been teams of lyricists, composers, and producers joining forces to create a song. Collaboration is simply part of the pop DNA. Is there a qualitative difference between co-written songs and solo songs? Can we evaluate the contributions of each individual writer to the collaborative creative process? We chose several pop icons who achieved mass commercial and critical success with both types of writing, and embarked on a journey to understand the differences between their works, as well as determine how their collaborations affected their songs’ contextual, lyrical, and musical aspects. We enlisted MyPart’s SongCrunch to analyze dozens of solo songs by prominent, classic and contemporary solo-songwriters, and compare them to tracks they’ve co-penned with a fellow prominent songwriter, in order to discern what exactly each writer brings to the proverbial table.

Our analysis focused on three primary aspects:

1. Lyrical Themes and Moods: the narrative and feelings conveyed by the lyrics, measured on a scale of zero (low association) to five (strong association).

2. Lyrical Writing Style: aesthetic preferences in lyric writing, including literary and linguistic devices such as repetition, rhyming and alliteration schemes, verbiage selection, etc.

3. Musical Composition Analysis: the song’s compositional features, including harmony (keys, chord progressions, cadences, etc.), melody (i.e. vocals, hooks), song structure, and arrangement.

Here’s what we found:

1. John Lennon & Paul McCartney

Lyrical Themes and Moods

Lennon and McCartney are arguably the most successful and prolific writing duo in pop history. A well-known hypothesis about the Beatles partnership posits that their work was a clash of beauty, timidness, and positivity on one end, with cynicism, energy, and brutality on the other.

We analyzed songs from Lennon and McCartney's repertoire that we know were definitely co-written by the pair, such as "She Loves You", "I Want to Hold Your Hand" and "In My Life” - arguably some of the best from the early/mid-era group. These songs grade exceptionally highly in features generally associated with romantic relationships, reaching the max in the categories of infatuation, love, and romance. Together, the duo scores higher in these areas than Lennon’s solo songs (despite him having written some fantastic love songs, such as "Oh My Love") and far higher than McCartney's solo songs- though it should be noted that we selected some of McCartney's more abstract pieces, such as "Band on the Run" and "Jet."

Early Beatles' songs were were more daring sexually, more hedonist, and dealt more with pleasure than Lennon and McCartney’s later solo tracks, which is unsurprising considering their initial work celebrated the height of their success during their twenties.

Examining the anger category is interesting, as it is one of the moods that most sharply differentiates the pair’s respective styles. The data reveals that Lennon’s post- Beatles solo tracks are angrier, more bitter, and more cruel than both McCartney's solo songs and the duo’s earlier collaborative work. Lennon’s solo songs also deal more with materialized dreams. A more surprising discovery is that early Beatles' songs were sadder than their later solo efforts (which could be skewed by our inclusion of "In My Life").

Lastly, despite the stereotype that early Beatles collaborations were deliberately calibrated for

commercial pop, the data alleges that the group scored higher on commercially unpopular themes such as criticism and satire than in their respective solo tracks, with McCartney’s solo works unexpectedly scoring higher in those particular categories than Lennon’s.

Writing Style

Beatles songs are famously efficient and hooky, and It would appear that McCartney's solo repertoire continues that commercial appeal, as he tends to reach the choruses relatively early (both in general and in comparison with Lennon’s solo tracks) in his songs. Alternatively, Lennon scored notably higher than McCartney in lyrical density, which is unsurprising considering he was known to be more verbose than his counterpart. Both writers use more slang in their solo years, maybe as a result of pop culture’s trend towards informality.

Overall, the data comes to contradict the preconceived notion that the pair’s individual writing became more sophisticated over the years, as their earlier collaborative (Beatles') tracks are richer in everything from usage of rhymes and number of groups of rhymes, to perfect rhymes at the end of lines- a crucial ingredient in advanced songwriting. It would appear that through their partnership, Lennon and McCartney created a ‘tighter’ linguistic song-making machine. One only needs to catch a glimpse of Peter Jackson’s “Get Back” series- which provides a fly-on-the-wall perspective of their creative songwriting process during their last days together- to understand how teamwork gave their songs a distinct, additional edge.

Musical Composition

Whilst many saw McCartney as the Beatles' composer and Lennon as the primary lyricist, their solo scores are almost identical in compositional features such as number of chords, inversion, unique chords, and number of seventh chords. In fact, our analysis reveals remarkable similarities between Lennon and McCartney’s respective individual works, as well as the songs they co-penned during the early 1960s.

One harmonic feature in which they slightly differed was in harmonic rhythm (chord substitution frequency), with the pair scoring higher in their Beatles’ songs than in their solo tracks.

SongCrunch suggests that McCartney, known for his vertical melodies, indeed used a broader range of notes in his solo work than Lennon (known for his horizontal tunes) or

Beatles tracks. Alternatively, Lennon scored higher in other melodic features such as average hook length.

2. Mick Jagger and Keith Richards

Lyrical Themes and Moods

Often perceived as the more egocentric, cynical, and sexualized version of their alleged rivals from Liverpool, The Rolling Stones' Mick Jagger and Keith Richards formed one of the most flourishing songwriting combinations in rock history.

While the Beatles appear to be more equal collaborative partners, the Stones seemed to have more clearly defined roles, with Jagger responsible for the lyrics, and Richards for the music.

We compared Rolling Stones tracks from their heydays in the 1960s- "The Last Time" (1965), "Satisfaction" (1965), and "You Can't Always Get What You Want" (1969)- to Jagger and Richards' solo efforts during the 1980s and 1990s.

The data reinforces one aspect most of us knew about the Stones: they did not write many love songs, at least not romantic ones. They instead preferred racier, “no-strings-attached” songs. As they transitioned into their solo careers, their songs scored higher in infatuation, love, and romance, perhaps indicating a coming-of-age and growing emotional maturity to be expected of 50 (rather than 20) year-old lyricists.

The duo’s respective solo songs also score higher in themes such as empowerment and self-esteem, and lower on criticism. The AI also revealed that the songwriters were more cynical during their solo years than during the Stones’ days.

Writing Style

Jagger and Richards reached the chorus/hook faster in their Stone’s songs than in their solo works, but used approximately the same amount of slang. They appear to have used more perfect rhymes as individual songwriters, with Richards using more rhymes per word than his former partner - a characteristic that also shone through in many Stones' classics. Alternatively, Jagger's solo songs demonstrate higher lyrical density. Richards' solo songs tend to be less repetitive than those of Jagger and the Stones.

Musical Composition

As in the case of Lennon and McCartney, our data shows remarkable similarities between Jagger and Richards' solo years and songs they co-wrote during the early 1960s. The AI shows that their compositional ammunition is strikingly similar in features like unique chords and number of seventh chords.

One may have suspected that Jagger's solo works would have a broader melodic range than those of Richards, since he was the vocalist. Here too, however, the similarities are evident. Meanwhile, Richards’ solo works are closer to the Stones style in terms of sequence length and number of melodic themes.

Taylor Swift & Bon Iver

Lyrical Themes and Moods

One of the most interesting contemporary collaborations is the unlikely union of pop superstar Taylor Swift, and Justin Vernon aka Bon Iver, a known figure from the alternative Americana/folk scene. Though on the surface the two could hardly be more different, their recurrent collaborations over the years- on “Exile”, “Evermore”, “Birch”, and “Renegade”- clearly prove their musical chemistry. These powerful tracks are equally marked by Swift’s solemn intensity and Vernon’s air of mystique.

The data reveals that Swift deals more with themes such as infatuation, love, and romance as a solo artist than in her collaborative work with Bon Iver. Her solo works (compared to solo Bon Iver and Swift-Vernon collaborations), also score higher in sex, hedonism, pleasure, yearning, longing, loneliness, and anger. In their collaborations, Vernon’s touch brings in themes and moods of success, criticism, feelings of detachment, cruelty, and realistic observation.

Writing Style

Bon Iver songs are less repetitive than Swift in both her solo work and in their collaborations, proving that Swift influences Vernon’s style as well. In the lyrical sense, she attracts him to her playground.

Their scores of slang usage, lyrical density and complexity are interestingly almost identical. When together, however, they use more sophisticated / less common words.

Swift and Bon Iver use a very similar percentage of perfect rhymes (overall) in both their solo and joint works. In terms of rhyme placement, solo Swift tends to employ more middle of line rhymes, while the Iver-Swift duo uses more rhymes at the end of lines. Their collaborations also scored higher in groups of rhymes (similar sounding rhymes throughout the song), have high group size variation (meaning that similar-sounding-rhymes were used selectively), and have more complex structure. Overall, as we saw with the Beatles and the Stones, in terms of linguistics, their co-writing creates richer textures.

Musical Composition

Harmonically speaking, in collaboration with Vernon and as a solo writer, Taylor Swift uses fewer unique chords, including triad chords, than Bon Iver’s solo work. Swift's harmonic rhythm is higher and she tends to repeat chord sequences more in her solo work. In both their duets and respective solo works, Swift and Bon Iver are highly diatonic.

Vernon scores higher in the versatility of melodic groups, meaning that his solo works are much less melodically repetitive. His hooks are also a bit shorter. Their collaborative songs, on the other hand, have fewer appearances of hooks, yet a higher number of themes.

2. Billie Eilish & FINNEAS

Lyrical Themes and Moods

Finneas and his brilliantly talented younger sister, Billie Eilish, form another creative partnership defining contemporary pop music. At just 24 and 20 years old respectively, the incredibly accomplished sibling duo have already won seven Grammy Awards together, and are up for seven more in the upcoming 2022 awards. As opposed to the three aforementioned pairs in this piece, we can only compare this duo’s collaborative work with Finneas’ solo tracks, as Billie has yet to work on her own at this stage of her career.

The data reveals that the siblings’ collaborative tracks score higher than Finneas’s solo songs in themes such as infatuation, love, and self esteem, but lower in romance and breakup. The pair's catalog achieved higher grades in hedonism, pleasure, and sleaziness, as well as yearning and longing. Billie’s songs are darker, angrier, more satirical, and sadder than Finneas’s solo tracks.

Writing Style

The duo’s co-credits are less repetitive, but reach the chorus faster than Finneas’ solo efforts. Finneas’s solo work contains more slang and uses simpler verbiage (fewer “difficult words”) than Billie Eilish songs, which might come to some as a surprise considering Billie’s nonchalant persona and slightly younger demographic.

Billie Eilish songs contain more perfect rhymes, are more dense in rhymes in general and rhymes at the end of lines in particular, and achieved a higher structural complexity score than Finneas solo songs. Overall, in terms of linguistics, their co-writing demonstrates greater sophistication/thoughtfulness.

Musical Composition

Billie and Finneas operate in the electro-pop realm with singer-songwriters sensibilities. Their collaborations contain more unique chords, more inversion, more seventh chords, and more chromaticism. The harmonic rhythm is similar, but Billie's contribution is evident in their broader melodic range in relation to Finneas’s solo tracks, as well as in shorter sequences with more vertical melodies. Their co-written songs also contain more distinct parts than Finneas' solo work.

Whilst Finneas has indeed stepped into his own as a solo artist, he seems to shine brightest when songwriting and producing alongside his superstar sister. Our analysis clearly reinforces her broad contribution to their partnership.

The Bottom Line

It is important to reiterate that this piece represents a somewhat limited view of these songwriters' full body of works, and that including more extensive catalogs in our research would undoubtedly render additional, more precise insights. That being said, our analysis shows that the creative process of songwriting very clearly benefits from the power of teamwork.

When the chemistry is just right, working as part of a team can elevate a writer’s craft, challenge their comfort zone, expose them to new audiences, and increase their productivity. Each individual writer in the iconic partnerships examined above proved to contribute their unique style, perspective, and areas of expertise- from particular themes, lyrical devices, harmonic or melodic features- so that together, they were able to create magical results.

Moreover, thanks to the continued globalization of music, gradual diminution of conventional genre boundaries, and advancements in technology and connectedness, the process of songwriting teamwork is becoming easier and more accessible. As the recent genre-bending partnerships between BTS and Coldplay (“My Universe''), or Young Thug and Elton John (“Always Love You” feat. Nicki Minaj) have demonstrated, songwriting tandems in pop music are here to stay, and rightfully so.