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.
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.