It seems common these days to try to explain everything through evolutionary theory. For example, supposedly art exists because it makes us more likely to survive for some reason. There are at least 2 major problems with such thinking.
- First, an important fact about evolution is that it uses what it has to work with. Organisms do not evolve through careful planning, instead the traits that exist and show up are then selected. Consider, then, a trait A that shows up and becomes popular at some point in some organism, for reasons that we will discuss later. It may be that using some aspect of trait A is of benefit to survival, and the entirety of trait A is retained for that benefit. It is valid to say that part of trait A is useful for reproduction, but it is not quite valid to say that "trait A is explained by its reproductive benefit". A may contain many other aspects that are not directly of practical benefit, but perhaps more importantly, A did not arise due to a need to maximize fitness. We purposefully did not mention the original reason for it showing up: Perhaps it was chance, or perhaps something else.
Regarding such "something else", we can imagine that art arose through some intentional act at some point in time - a great leader used it to justify his rule, for example, or it was derived from religious visions seen under the influence of some drug. Art may have remained relevant later on due to some reproductive benefit, but that is just why it persists, not why it arose, in this story.
If you are tempted to say that the origin matters less than what sustained it later on, then that is of course a fair position. But here is a counter-argument: Imagine that a particular problem faced a species. There are various ways to work around that problem; whichever is implemented first is the one that will become useful and persist for a very long time. So that the first solution to appear is of reproductive benefit is true and important, but which solution actually appeared and became part of the species became such because of specific "origin" reasons: Why that solution showed up when it did, and why others did not do so earlier. So a lot of the information about the species is lost by considering just the retention of the trait and not the specifics of the trait's appearance. To make this vivid, consider that the possible solutions can be very different from each other: The species becomes quite different depending on which solution is kept.
- Second, evolutionary selection is a very dull blade. It selects an entire organism at a time, in effect, not for each trait separately. And the reasons an individual survives, especially among species like humanity, can involve to large degree factors like culture, intelligence, and so forth. But even in "less" sophisticated creatures non-immediate effects can be crucial: Such is sexual selection. With humans we have sexual selection as well as cultural selection and many other factors. The amount of "noise" between actual reproduction and survival and between those factors is tremendous. It is far from clear that reproductive fitness is a major factor in the actual traits we see day to day (art, personality, religion, etc.), even if it does "back" things in an important sense. We are also "backed" by particle physics (without which we would not exist), but we do not say that it determines specifically properties of our species like art or religion or poetry.
Future generations will laugh at our present time and its morbid fascination with using evolutionary theory to explain everything.
(Background: Adam Kirsch on Boyd, Pagel, and Kandel)