Music: Adaptive or Not Adaptive?
Does music have a biological function?
If so, what is it?
Science has not yet settled the question of whether or not music is adaptive, ie whether or not music has a biological function.
(Within the context of evolutionary biology, "biological function" and "adaptation" both refer to any aspect of a living organism, in this case humans, which is genetically determined, and which increases expected long-term reproductive success.)
I have recently proposed a theory that music is a glial illusion, and that, more specifically, music is a superstimulus for the glial perception of slow speech tempo.
But actually we can step back a bit, and just assume, for the sake of making an assumption, that music is not adaptive, and then see where that takes us.
Historically (or Prehistorically) Adaptive?
When we ask if music is adaptive, we are asking a question about the status of music now.
If we consider the status of music in the past, then the two choices of adaptive or not adaptive can be expanded to three choices:
- Music is adaptive
- Music was adaptive, but the reason for it being an adaptation has gone away, and it is no longer adaptive<./li>
- Music is not adaptive, and it has never been adaptive.
For the sake of the current discussion, I am going to assume the stronger third option, that is, there is, and there never has been, anything about music that is adaptive.
Questions To Ask
If we decide to assume that music is not adaptive and never has been, then various questions arise.
The primary question is:
If music is not adaptive, then how come it exists at all?
One possible answer to this question is that music exists because it is a side effect of some other thing which is an adaptation. Which naturally leads to the question:
If music is a side effect of something that is an adaptation, what is that adaptation?
A different kind of question has to do with finding other things that might be like music.
That is:
Do there exist other things which are not adaptive, which are similar to music?
And a final question has to do with mitigation:
If music is not adaptive, are there any secondary adaptations that have evolved for the purpose of mitigating the costs caused by the existence of music as a thing which is not adaptive?
The previous question about finding other similar non-adaptive things is relevant to this question about mitigation, because if we can find examples of other non-adaptive things similar to music, then there might be examples of secondary adaptations relating to those other things.
A Possibly Similar Non-Adaptation: Alcohol
In some ways music is like a recreational mind-altering drug. In particular:
- People enjoy consuming music.
- People will go to considerable effort to create music, so that it can be consumed.
- Music causes or alters emotions (albeit in some fashion that is hard to pin down exactly).
One obvious difference is that music is not a chemical that is ingested in some manner, and it doesn't damage your liver (it can damage your hearing, although that is mostly only possible with very modern technology).
There are many different mind-altering drugs that people use in the modern world, some of them stronger than alcohol, some of them weaker, some of them more or less addictive.
However alcohol is one drug that has a long evolutionary history, so that makes it a good example to start with. Most of the other drugs have been invented or discovered much more recently, evolution of resistance to those drugs to be evident to a degree that can be unambiguously observed or measured.
(It might turn out that there exists some other drug whose mind-altering effect is actually more similar to that of music, but I'm not currently aware of any such drug.)
The first in my list of questions above related to a non-adaptation being a side-effect of some other adaptation.
For some mind-altering drugs the drug is known to act on particular neurotransmitters in a fashion that relates directly to known mechanisms of "pleasure" and "reward seeking".
Alcohol has a general inhibitory effect, and it would appear that the exact reasons why this leads to a state of enjoyment are rather complex and not necessarily well understood.
Benefits of Alcohol
I have identified alcohol as an example of a non-adaptation.
But of course we do need to ask if alcohol is indeed a non-adaptation.
I think it is generally agreed that alcohol is not "good for you" overall.
However, there are situations where alcohol can be beneficial to particular individuals in certain sitations.
One effect of alcohol is that it increases risk-taking behaviour.
The thing about taking risks is that it can end well or it can end badly.
In as much as alcohol does not one's judgement skills, any increase in risk-taking will on average probably not be beneficial.
Yet there will be situations where it does end well, and in some cases a sober person may rationally decide that they need to temporarily increase there own tolerance of risk in a particular situation to achieve a good result.
For example, so-called "dutch courage", where a boy gets a bit drunk and then approaches the girl.
If that works out OK, leading to marriage and children and grandchildren, and the alternative is that the boy would never have approached the girl at all, then that would be a clear case of alcohol providing an increase in long-term reproductive success.
The relevance of this to studying the adaptiveness of music is that there may be situations where music cause someone to think of something, or to do something, which has some long term benefit, even though, considering the overall long-term costs involved in music consumption and production, the costs of music on average exceed its benefits.
(Pre)History and Secondary Adaptations
The Promise of an Evolutionary Perspective of Alcohol Consumption gives a summary of what is currently known about the evolution of human adaptations to the availability and consumption of alcohol.
The paper identifies two major evolved adaptations relating to alcohol:
- Evolution of a variant of the gene ADH4 for enzyme Alcohol Dehydrogenase, occurring about 10 million years ago, which increased the efficiency of the enzyme in metabolizing alcohol by a factor of about 10.
- Evolution of a variant of the gene ADH1B about 9000 years ago, in what is now the eastern part of China, which increases the rate at which alcohol metabolizes into acetalhehyde, to a degree such that consumption of alcohol results in the accummulation of acetaldehyde in the body, where acetaldehyde is actually more poisonous than alcohol. This apparently perverse adaptation provides resistance to alcoholism, because the uncomfortable symptoms of acetaldehyde poisoning discourage the consumption of alcohol. (The paper identifies other distinct variants of the same gene with similar effects that have recently appeared in other human populations.)
These two evolutionary events correspond roughly to two phases in the history and pre-history of the consumption of alcohol by humans and human ancestors:
- The consumption of naturally occurring alcohol in over-ripe fruit.
- The deliberate production of alcohol from agricultural produce.
Alcohol is a chemical sustance, and these evolutionary adaptations consist of easily identifiable variations in enzymes which are proteins directly represented in our genomes by the genes which code for those proteins according to the well-known genetic code.
If similar types of adaptations have evolved in relation to music, they will mostly likely not involve simple variations in enzymes, because music is not a chemical substance.
In the case of music, if we want to discover secondary adaptations which act against the primary effects of music on the brain, then we are limited to looking for aspects of our perception of music which could be intrepreted as being such secondary adaptations.
The Dichotomy Between Communicative Speech and Music, and the Suppression of Truth Evaluation
One possible candidate for a secondary adaptation against the effect of music is the dichotomy between communicative speech and music.
"Communicative" includes all conversational speech, but it also includes some types of audience-directed speech, ie where one person is talking with to a group.
The defining characteristic of communicative speech is that the speaker expects to be taken seriously. Not necessarily to the extent that the speaker expects their audience to unconditionally believe what they say, but rather that they expect the audience to consider what has been said as something advanced as likely or at least possible to be true, and the audience should make some effort to determine their own opinion about whether or not the speech content is true, and depending on the specific context of the speech, but especially in an informal one-to-one conversational scenario, the listener would be expected to give some feedback to the speaker that is indicative of what their opinion is about the possible or likely truth of what has been said.
None of this stuff happens when music is being performed.
If we consider just instrumental music, then of course there is no speech content in instrumental music, so there isn't any speech content to be evaluated.
But music can contain speech, that is, songs are a form of music.
What happens to the dichotomy between speech and music in this case?
One might expect that the treatment of a mixture of music and speech takes a form that is halfway between the treatment of music and the treatment of speech.
But this is not what happens. What happens instead is that music containing speech is treated as if it is music, and as a result, the speech contained within music is not "communicative". Listeners the lyrics of songs do not make any effort to evaluate the possible or likely truth of the content of the lyrics, and there is no expectation that they should provide any feedback about any such evaluation to the singer.
To put it another way, if you are having a conversation, and you start singing your conversation instead of speaking, as if you were living inside a BroadWay musical, you will not be taken seriously by your listeners.
One of the major consequences of listening to music is that it intensifies emotional responses. If listeners to musicalized speech did not realise that the emotional effect was due to the music, they might be duped into thinking that they truly had an intense emotional response to the what was in the speech, and that, perhaps, they should take some action in relation to that.
So it is plausible that a secondary adaptation of some kind has evolved, to prevent listeners from over-reacting to the emotional intensification that music causes, and to prevent them from getting confused about whether their emotional response is "genuine", or whether it is artificially enhanced by the music.
On the one hand it might be sufficient to be aware that music is involved, and therefore any emotional effects are artificially intensified. But our brains seems to take it further. We are not just made aware that music is involved. Something in our brain automatically responds to the perception of music by fully suppressing the process of "truth evaluation" that normally occurs during spoken conversation.
(I will add a caveat that this suppression of truth evaluation does not prevent a listener from evaluating the possible or likely truth of song lyrics, if they really want to. It would be more precise to say that the perception of music triggers suppression of the urge to evaluate truth. In other words, during normal conversation, the listener will be constantly evaluating the truth of what is said, and there isn't really any way that they can stop that process of evaluation. When listening to songs, this automatic evaluation of truth is disabled, but it can be forcefully enabled if the listener makes a conscious effort to do so.)