HOW powerful can a song or a tune be? I had two musical experiences this week, wildly different in mood, which richly answered this question. Firstly, there was a camera phone clip from a shattered apartment in Beirut. Windows blown in, cushions punctured with shards, the ceiling meeting the floor.

The aftermath of a dockside explosion of massive amounts of ammonium nitrate, one-10th the power of the Hiroshima bomb. Incompetence, or attack? We don’t yet know. In the meantime, amidst her domestic ruin, a prim, elderly lady sits at the house piano. She starts tentatively playing … Auld Lang Syne. The daughter filming it, Hoda Melki, says her mother is “pushing through her pain”, making “beauty from ashes”.

Certainly that – and hard not for the throat to be caught. Scotland’s classic paean to remembering old relatives and friends, with “cups of kindness” sends chords through the lady’s chaos. Its emotional power travels the globe, and surfaces to give a sufferer strength in their fragile Middle Eastern city.

My second experience of a song’s power comes from one that hasn’t ever been heard – although we do at least have the chorus: “Rise up! People gotta rise up!”. This is a fictional one-hit wonder from 1990, written and performed by the fireball Clio Campbell, who cartwheels through Kirsten Innes’s epic and moving new novel, Scabby Queen.

Scabby Queen is about many things – the way older women artists are treated by the culture industry; the crunch between early trauma and creative drive; the weird, destructive trip we’ve been on since Thatcherism; the thrawnness of the Scottish character. And brilliantly so. But it’s also about the aftermath of one big pop song, catching the mood of the times (the poll tax militancy at the turn of the decade). “Rise Up!” becomes both balloon and ball-and-chain for Clio as an artist.

Tediously, it’s the song that everyone has to hear, for increasingly nostalgic reasons, at every gig she does. But Clio can’t deny how consistent and continuous she is with that moment. She remains the same flame-haired, red-lipped rebel, who refused to mime and showed her “Can’t Pay Won’t Pay” T-shirt at the end of her Top of the Pops performance.

Clio is increasingly embattled as the years pass – not only artistically, with one faltering musical follow-up after another, but also politically, as the waves of neoliberalism beat against her rackety, rainbow resistance. She ends up taking her own life a few weeks short of her 51st (not a spoiler, that’s how the book opens). And on Clio’s death, for days afterwards, it’s the only song that anyone can hear, as they go about their daily business. Until even that phenomenon fades.

But between Auld Lang Syne and Rise Up! we have a petri dish that can show us what songs do for humans. I’ve been reading the neuroscientist and musician Daniel Levitin, who also played with and produced for Steely Dan, David Byrne, Stevie Wonder and Joni Mitchell.

Levitin digs into how songs, in particular, are longstanding answers to some enduring challenges for our species. His main assertion is that we have sung songs for hundreds of thousands of years, in order to better connect us to our fellow group members. The one thing you can equally say about our two songs is that they are triggers for social bonding, in different forms.

Out of Robert Burns’s usual adaptation of folk melody and lyrics, Auld Lang Syne has become a global anthem of comity and togetherness. It’s the ritual melody that passes us between each new year (at least according to the Westernised calendar). Indeed, it even comes with a ritual dance. The circle of celebrants cross their arms and hold hands, come closer and then expand outwards, turning their bodies to face to the future.

Rise Up, as the imagined (though creepily accurate) Q reporter writes in Scabby Queen, was written by Clio to be sung at poll-tax protests, and from there gets picked up by a major record company.

INNES even imagines a bland Labour MP (2010 intake) writing blandly that Clio’s song is about “the idea of communities coming together to resist a specific injustice … I’m fairly sure she started something in me!”.

In Levitin’s book The World In Six Songs, he literally calls the earliest songwriters and singers “politicians”. By this, Levitin means that singing, and especially collective singing, can “induce feelings of happiness, safety and security in a group”.

This produces an evolutionary “advantage” for such vocalisers, who can get others to co-operate with them by inducing “good feelings” in song. Their songmaking talents are “calming, energising, organising and inspiring”.

In Scabby Queen, Clio clearly has an elemental talent for this. She not only reduces rooms to a quiet stillness with the sheer beauty of her voice, she also takes the chance to constitute her audience as a community of purpose. How delightful. The standard charge flung at political popsters – “just shut up and sing, pal!” – turns out, according to evolutionary neuroscience, to be a fundamentally unnatural request.

Indeed, when Innes sources Rise Up! in a protest movement, she is reflecting the use of song over millennia “to allow subgroups, particularly the disenfranchised, to cohere”, as Levitin writes. “Music has historically been one of the strongest forces binding together the disenfranchised, the alienated.”

(This is one of the tenderest parts of Scabby Queen – where the older Clio, and a south London rapper called Hamza Hassan fall deeply for each other, her folk rebelliousness mixing with his grime-led alienation).

But Levitin’s social-bonding theory of song works equally well for Auld Lang Syne, though in a gentler, more encompassing register. He wonders how humans have generally managed to peaceably live in units of thousands, and then of hundreds of thousands, beginning about 3500 years ago.

“I believe that synchronous, co-ordinated song and movement were what created the strongest bonds between early humans, or protohumans,” continues Levitin. “And these allowed for the formation of larger living groups, and eventually of society as we know it.”

The professor reports a beautiful experiment in synchrony he once conducted. Two humans tap their fingers in time to a metronome – and then tap their fingers in time with each other. In the latter case, their fingers co-ordinate more tightly together than against the machine’s click. In Levitin’s words: “Humans accommodate one another’s performance, a situation of co-adaptation.”

Seen from the heights (or depths) of evolutionary mind-science, then, Auld Lang Syne fulfils one of the primal functions of song. It re-weaves the social bond between kin, non-kin, strangers and friends alike.

It’s worth noting how explicitly non-religious the lyrics of Auld Lang Syne are. The sentiment comes from memories of a shared childhood, roaming around freely in nature. A memory confirmed by drink and adult conviviality, which makes a point of recalling absent (and departed) friends.

And all of this in a primal, lullaby melody, which (according to my YouTube research yesterday) suits big-band arrangements as well as Russian balalaika. No wonder that Hoda Melka’s mum reached for the song in her blasted Beirut flat. It throws a sonic arm of stability and care around her shattered homestead.

Hardly for the first time, Scotland is already profoundly woven into the world, as the world waits for our official arrival. Closing suggestion: isn’t this the obvious, post-indy Scottish national anthem in waiting? A song the world already sings – joyfully, harmoniously, in happy celebration? Right under our noses, all this time?