Music as social glue

In Martin Scorcese's The Wolf of Wall Street, a primitive chant whips Jordan Belfort's stock brokers into a euphoric state of solidarity. (Note: NSFW. Chanting starts at about 1:00.) The chest-beating rhythm and wordless tune (consisting of just four pitches) evoke our early ancestors singing and dancing before a hunt.


In fact, recent psychological findings are at least consistent with the idea that human music-making evolved as a social bonding mechanism. Rhythmically moving together is unique among cooperative activities in its ability to promote feelings of social affiliation and empathy. Young children are more likely to engage in helpful behaviour with someone after they have rhythmically moved together.

 Why should rhythmically moving together act as such a powerful social glue? One idea increasingly supported by neuroscience is that the act involves simulating or "playing out" another person's actions without necessarily producing them yourself. Simulating another person's actions may allow you to gain insights into their emotional state and make predictions about their future actions in a more direct way than through observation. For this reason, simulation may have had survival value for our early ancestors in deciding whether someone is friend of foe. Likewise, performing easily-simulated, predictable rhythmic movements, like clapping your hands or stomping your feet at regular intervals, may be an effective means of signalling good will towards others.

One interesting recent study showed evidence for simulation among musicians using transcranial magnetic stimulation (TMS). TMS sends electrical impulses to the scalp that can be used to selectively impair parts of the brain temporarily and harmlessly. The experimental task was to play a right hand piano part in synchrony with an audio recording of the left hand part. Prior to the experiment, one group of musicians had no exposure to the left hand part. The other group practised playing the left hand part, which, upon subsequent hearing, would presumably elicit a motor simulation of those actions required to produce it.

In the experiment, both groups played the right hand part in synchrony with an audio recording of the left hand part. The recording contained accelerations and decelerations in tempo typical of an expressive music performance. At tempo changes, TMS was delivered to the right motor cortex (which controls the left hand). Remarkably, only the group that had practiced the left-hand part beforehand were impaired in their ability to follow the tempo changes. This suggests they had been attempting to simulate the actions required to produce the audible left-hand part. More strikingly, extent of impairment was greatest for those individuals that showed a stronger tendency to adopt others' perspectives on an empathy questionnaire.