Evolutionary psychologists seem to assume that all of an organism's traits must be the result of natural selection. This is not the case. As Stephen Jay Gould pointed out, it is entirely possible that a given trait is merely a by-product of another trait that is adaptive. This by-product may in fact thwart reproductivity ("fitness") as long as this is outweighed by the benefits of adaptive trait with which it is associated.
Further, we know little about our ancestral environment and its selective pressures, and consequently the claims of evolutionary psychology cannot (excepted for more generic and less controversial cross-species claims) be tested. So when someone excitedly tells you that some human behavior evolved for such and such a reason, you should keep in mind that you're being fed a great big heap of unscientific bullshit disguised as science. Is rape a "secondary sexual strategy" that evolved in disadvantaged males, or is it the by-product of aggressive human behavior that serves a variety of adaptive functions in human beings?
No one knows for sure, because we know nothing about the relevant selective pressures (which include very variable cultural pressures). But given our lack of knowledge, the account involving a highly specific bit of selection seems far less likely than the more general account involving aggression. The same goes for other evolutionary generalizations about male and female sexuality in popular science books and articles today: they're groundless speculation, and likely false.
This cult of reductive, un-founded speculation has recently set its sights on culture and art. Adam Kirsch gives a nice review of a few of these attempts in The New Republic.
Brian Boyd argues that art enhances our fitness by refining the pattern-seeking critical to cognition and social interaction, a claim that we could only prove by showing something like "people who write symphonies or listen to symphonies have more children than people who do not." This is obviously an absurd claim. Kirsch further notes:
As Kant famously taught, the very definition of the aesthetic is that it is disinterested, that it has meanings but not utilities, that it suspends our involvement with practical and goal-oriented life, that it puts life at a distance so that we can judge it and escape it and even reject it. A truly Darwinian account of art would have to embrace this phenomenological reality, rather than simply positing what its premises compel it to posit, which is that art is essentially useful because it serves the biological cause of reproductive fitness.
Mark Pagel argues that culture (including art) is a "strategy for survival" because it promotes group cohesion; but this requires the mechanism of group selection, which is not widely accepted by evolutionary biologists.
Finally, Eric R. Kandel seems to think that the biology of aesthetics will help make aesthetics more objective. But:
When it comes to aesthetics, however, the subjective impressions are the objective facts, to which we have full access without knowing a thing about neurons. A neurological analysis of our experience of art tells us as little about the meaning of that experience as a chemical analysis of the pigments of a painting would tell us about the painting’s meaning. It is not scientifically false, but it is aesthetically pointless. It is an imperious category mistake.
A more plausible explanation of art and culture is that they are by-products of being very smart, which is evolutionary beneficial for obvious generic reasons. They are not merely a matter of survival or maximum reproductivity, but are what happens when survival is taken care of and we can redirect are excess energy to comparatively useless things. Compare Nietzsche's notion of "overflowing" (and his more sophisticated account of the origins of altruistic cultural behavior); and Aristotle's claim that the transition to the polis from more primitive associations occurs precisely at the point where flourishing rather than mere necessity is the overriding motivation. Or to quote Nietzsche from On Truth and Lie in the Extra-Moral Sense: “neither the hose, nor the gait, nor the clothes, nor the clay jugs give evidence of having been invented because of a pressing need."
Beyond the question of origins, there's the matter of explanatory relevance (and this is applicable especially to Kandel's attempt to apply neuroscience to aesthetics and Kirsch's criticism of it as an "imperious category mistake"): if someone asks me why I'm grabbing food from the fridge, I don't launch into an explanation of the fact that I evolved to do so; nor do I go back to the very first cause of my behavior I can think of -- the big bang; nor even do I describe the functioning of my brain. I say, "I'm hungry." This is a perfectly good explanation that tells my interlocutor what they really want to know. This is not to say that these other causes aren't of scientific interest. It's just that they're not relevant in this context. When human beings study and formulate explanations about literature, they're interested in something like the "I'm hungry" explanation, albeit a far more sophisticated version: in other words (and as Kirsch notes), they're interested irreducibly in subjective mental states. These states cannot be reduced to something else without discarding the relevant object of inquiry. When you study the neuroscience of aesthetics, you are studying neither aesthetics nor art; likewise, studying the neuroscience of how we do mathematics will never yield discoveries in the field of mathematics. Such confusions seem to be our contemporary version of the error of psychologism.
-- Wes Alwan