Musicality and Behavioural Modernity

17 October, 2007
The development of the human ability to perceive musicality may have triggered one of the most important events in human evolution: the appearance of modern behaviour.

Music as a Super-Stimulus

If music is a super-stimulus, then it must be a super-stimulus for something. We can call the relevant perceived quantity musicality. Musicality is a perceived quality of something else, and music is an artificial stimulus with a much higher level of musicality than that something else.

The most obvious candidate for "something else" is speech, because that is the thing other than music which has the most characteristics analogous to the characteristics of music. Which leaves us with the assumption that musicality is a subtle but somehow important perceived property of speech.

So far this is just a brief re-statement of the super-stimulus theory of music, as explained in my book What is Music? Solving a Scientific Mystery.

The Meaning of Musicality

It's one thing to assert the existence of "musicality" as a quality of speech. But a number of questions are left unanswered by this assertion:

To answer the first two of these questions, we might assume that there exists some very important aspect of speech which needs to be perceived by the listener in a manner which is carefully hidden from both the listener and speaker.

As it happens, the theory of Uncritical Listening that I have developed, for reasons completely unrelated to the explanation of music, suggests a requirement for an aspect of speech perception with just these properties.

The major assumption of this theory is that, under some circumstances, a listener uncritically accepts the truth of what a speaker is saying. The purpose of such acceptance is to enable the efficient "bootstrapping" of a sophisticated world-view. However, such a learning strategy is intrinsically risky, because the listener is left open to manipulation by the speaker. A first strategy to mitigate this risk is for the listener to give no external sign as to whether or not they accept the truth of any given pronouncement. This necessitates that the listener not even be conscious of whether or not they accept it, since any conscious feeling can affect the behaviour of the person having the feeling in a manner which may be observable to onlookers.

A second strategy, and one which brings us to the main topic of this article, is to be sensitive to any aspect of speech which indicates that what the speaker is saying is truly what they think, and not something being said with a conscious intention of deceiving or manipulating the listener. If musicality is a property of speech which indicates such a lack of ulterior motive, then the perception of musicality could play a major role in this process of uncritical listening.

Risks of Using Musicality as Criterion for "Truth"

If musicality is an indicator of "truth", an immediately problem is that music then becomes a false bearer of truth. We would expect that any pronouncement set to music would be received by all listeners as probably true, and even more true than the normal level of truth ascribed to normal speech.

Although very strong music can create a feeling of "truthiness", this feeling is usually very temporary, and we do not generally observe that people can be persuaded by arguments set to music.

My previous article Music: A Drug, Which Used To Be Stronger Than It Is Now suggests an explanation for the non-effectiveness of music as a persuasive device: that in order to safely exploit the perceived musicality of normal speech, the brain must learn to identify music as a distinct category of pseudo-speech with an artificially high level of musicality. Having identified music as such, it can then switch off whatever the normal response is to perceived musicality.

The Evolutionary Scenario

Putting all these ideas together, we can reconstruct the following series of events that occurred somewhere in the early history of the modern human species:

As to when these events occurred, the postulated explosion of culture can plausibly be identified with the appearance of so-called behavioural modernity (or more simply, "modern behaviour"). If the discovery of music had a truly damaging effect on the ability of early humans to look after themselves, then this could be identified with the human population bottleneck that apparently occurred somewhere in the same timeframe as the appearance of modern behaviour.

(It should be noted that explanations for a human genetic bottleneck fall into roughly two categories: (1) externally caused, (2) self-inflicted. An example of an externally caused disaster could be a volcanic explosion. However, it remains unclear why, out of many different African mammals, only the human species would come to the brink of extinction, especially given that human beings have a more varied diet and a greater range of lifestyle possibilities than most other animals. Theories of self-inflicted damage are more plausible, in that they portray the human species as a victim of its own success.)

Evolutionary Theories and the "Evolution of Music"

The notion of an "evolutionary" theory of music strongly implies that music itself "evolved". But evolution is something that happens to organisms, in this case humans, so it is only the response to music which has to evolve.

The evolutionary scenario that I just described makes this distinction clear. Far from music evolving as something "good for us", the history of the evolution is one of the human brain defending itself against the threat that music poses, but doing so in a manner which allows it to continue deriving benefit from the perception of musicality.