Is the existence of music proof of the human soul? Like the '21 grams' theory, Dr Duncan MacDougall's infamous idea that the loss of weight when someone dies is evidence of the soul leaving the body, does music show that there is more to us than biology? Or can it be explained purely in scientific terms?

"I think everything can be explained in scientific terms", says Oxford-educated Professor Lauren Stewart, head of the Masters programme at Goldsmiths University in London ‘Music, Mind, Brain’.

"How much of it we can do now, I'm not sure. For instance, one theory about why music can trigger our emotions has been explored in some depth by Leonard Meyer in the 50s and, more recently, David Huron, a musicologist and cognitive psychologist, in his book, 'Sweet Anticipation', which examines the relationship between prediction and emotion.

“Huron was not the first person to say this but probably the first person to come up with testable hypotheses." 
 

Prediction

Huron's theory is essentially this: evolution has programmed humans to get a sense of reward when we predict events accurately because this increases our chances of survival. As a crude example, if I can predict that the deer I am hunting will turn left and not right then I can kill it and feed my family. Music is pleasurable to us because it sustains our need to predict successfully. When it surprises us (defies our prediction) it elicits in us “laughter, frisson or awe” which comes from our natural response: fight, flight, or freeze (once we realise it is a non-threatening situation).

An example of this is found in tonality and meter. Whether we like one note over another depends on the tonal context of that particular song (ie. notes heard in one song sound terrible, but in another they sound fantastic). In the same way, we prefer notes to happen at predictable times (meter) rather than occurring randomly. This is again contextual. The context sets the expectation and therefore the quality of our attempts at prediction.

Stewart says: "Prediction and anticipation seems to be the middle-man between musical events and our emotional response to them. I think it's not the only thing going on, because you also have memory mechanisms and personal associations to particular songs and you've got lyrics and certain conventional properties of different keys and tempos that play into it as well, but I think anticipation is a nice, cognitive mechanism that explains where emotional response comes from in music."

We enjoy music not just for the direct pleasure, but also because of a range of other reasons: the ideas a song expresses which might challenge, excite, or comfort; the relationship people build with their favourite singer; the sense of belonging to a particular musical movement; the shared human experience of live music; and the connection between a memory and a song.

Huron admits his theory only covers the pleasure we get from expectation and does not include other factors that contribute to our engagement with music. "But," he says, "without a significant dose of pleasure, no one would bother about music". (p.ix, Sweet Anticipation, 2006)

So why do we have music at all? What’s the point?

“That's a controversial and very big question”, says Stewart. “Stephen Pinker, [the Canadian-born American psychologist and author] annoyed a lot of people because he referred to music as being pure auditory cheesecake, by which he meant there's no survival value associated with music per se.

"The reason that it's so pleasurable, and people assume it must be so important because we have these emotional responses to it, is a bit misleading in his view. He says it hijacks the pleasure circuitry of the brain, which has itself evolved for other purposes, being to seek out biologically useful things. But other people fundamentally disagree with that."

Stewart believes that music may have evolved as a social bonding mechanism. "Early humans used to exist in much smaller groups, in groups that required intensive one-to-one grooming, for instance, to keep the social bonds going. But, at some point in our evolutionary past, early humans existed in quite large social groups."

"It is now widely accepted that singing with others makes you feel close to them and even increases pain tolerance, but what was not known was if this effect scaled-up the more people there were in the group."

To prove this, Stewart recently collaborated with Robin Dunbar and his team at Oxford to research a group called "PopChoir", a collection of regional choirs which combine once a year in a singing event totalling about 250 people.

"We found that the effects were just as strong, if not stronger and, quite interestingly, it wasn't just that you feel more close to the people in your regional choir, when singing in the "megachoir", it's that you feel closer to everyone in the megachoir. Even individuals there that you've never met." (published in journal Evolution and Human Behaviour)

Popchoir Director and founder Helen Hampton said at the time: "I know of members who have been able to stop taking anti-depressants because of their new-found confidence, raised self-esteem and the new and supportive friendships they have made in the choir.

Singers reported an alleviation of symptoms of illness, from asthma, to cancer, to crippling pain and yet the truth is that science still doesn't know for sure the exact purpose of music or why it came about. Stewart adds: "There's many other theories of the role of music in evolution to do with mother-infant communication and mother-ese and the sing-song style of communication."