London - Sad songs, as Elton John suggested all the way back in 1984, say so much. Elton - or, more accurately, his lyricist Bernie Taupin - was clearly on to something: sad songs have increasingly become the prevailing musical currency.
Where once we revelled in the unambiguous joys of thrilling pop songs, we now prefer them as bleak and miserable as the average British summer.
This is no mere conjecture. Psychologists have, albeit in inverted commas, proved it.
A study from the universities of Toronto and Berlin has concluded that songs have indeed become progressively sadder over the past 50 years, both in tempo and mood.
Its analysis of the most popular 1,000 songs since 1965 has revealed that, with each passing decade, the biggest hits have become more lugubrious and reflective. In the 1960s, 85 percent of songs were written in a major key; today it's just 42 percent - and, of course, the more minor the key, the sadder it sounds. Meanwhile, today's average song speed is a listless 100 beats per minute compared with 116 five decades ago.
There is a reason for this, according to the report's co- author Glenn Schellenberg.
“People like to think they are smart,” he suggests. “And unambiguously happy-sounding music has come, over time, to sound more like a cliché. People have come to appreciate sadness and ambiguity more. Life is more complicated, and they want the things that they consume as pleasure to be similarly complex.”
It's been a seismic shift. Where the carefree days of the 1960s were accompanied by the exclamatory pop songs of The Beatles, the 1970s by Abba's life-affirming kitsch, and the 1980s by Wham!'s silly ebullience, such frippery has now officially gone into recession, replaced by, frankly, the doom and gloom merchants.
Take grunge, which in the 1990s killed the happy hedonism of heavy metal and replaced it with stomach-ulcered angst. Then, soon after, Radiohead removed the posturing from British rock altogether in favour of post-millennial tension, and a deliberate absence of melody. (And when The Darkness tried to put it back, we all laughed, quickly discarding them.)
Even dance music has been affected. Kanye West, hip hop's best advert for extrovert living and monomaniacal arrogance, delivered, in 2008, an album called 808s & Heartbreak in which he sounded all but suicidal.
The virus has spread. One of the most celebrated artists of the year is Lana del Rey, an American beauty as melancholic as an octogenarian on her deathbed lamenting lost love. Coldplay have taken their maudlin anthems - the slower, the more effective - into stadiums worldwide. Adele has reinvented the power ballad.
And how else to explain the preponderance of Damien Rice covers on The X Factor? TV talent shows are surely places for joyful plastic pop, not the navel-gazings of either Rice or, for that matter, Leonard Cohen, whose magisterial Hallelujah was 2008's X Factor winner Alexandra Burke's winning single.
But Hallelujah was chosen for good reason: the show's producers realised, like Professor Schellenberg, that we are all in the grip of our own existential crises these days, worried about our lives, the economy, the Premiership. And we want our inner pain articulated by those who do it better than we ever could - even on Saturday-night telly.
Of course, there will always be exceptions to the rule, and pop can still bring uncomplicated joy. The authors of the research cite Lady Gaga, for example, whose single Born This Way, they say, “sounds fresh, recalling popular music from an earlier time”.
And there are further anomalies to remind us that pop doesn't have to be exclusively morose. Take Psy, quite possibly the happiest South Korean who ever lived, and surely the only South Korean to score a UK top-three hit. His single Gangnam Style is a nonsensical global smash, a proper pop song that, in this current climate, is practically alone in shining a light at the end of a very long tunnel.
But, don't worry, Psy's a flash in the pan, clearly. Normal, glum service will be resumed shortly.
MUSIC THEN ... AND NOW
Happy songs of the 1960s
'She Loves You' by The Beatles
Possibly the most uncomplicated love song ever written. “She loves you, yeah yeah yeah.” And, as a consequence, the happiest.
'Daydream Believer' by The Monkees
A glorious bolt of melodic honey, lovingly sung by four young men not yet tainted by fame. That would come later.
'Shout' by Lulu
Typifies the thrill of youthful vim (Lulu was 15) with its introductory war-cry of “We-e-e-e-ellll?”.
'My Girl' by The Temptations
Blissful five-part harmonies about the bliss of being in love.
'Be My Baby' by The Ronettes
Phil Spector's most gloriously life-affirming pop song, as glittering today as it was 50 years ago.
Sad songs of today
'Someone Like You' by Adele
Our best modern singer rakes over the coals of a dying love, hoping to meet someone comparable.
'Under the Westway' by Blur
An antidote to the feelgood Olympic summer, focusing instead on the city's underbelly.
'Video Games' by Lana del Rey
Set to a funereal pace, Del Rey broods on the possibility of love in her hometown. She does not sound happy.
'Us Against the World' by Coldplay
The moment in the stadium when everybody reaches for their lighters.
'The A Team' by Ed Sheeran
There's this drug-addled prostitute, and Sheeran takes pity on her. Saintly! - The Independent on Sunday