I put up a moderately favorable review of Virgina Postrel's the Substance of Style last week.   I was critical of the book for documenting at length the existence of what Postrel terms "the aesthetic imperative" but NOT laying out a well grounded structural theory for why the imperative exists.

This article in Tyler Cowen's blog lays out an excellent social/evolutionary psych model:

Why fashion? Why spend all that money on silk and sequins? Could it have to do with sexual selection?

With fashion in the game, a woman not only sends out face and figure cues—which are fairly easy to fake—but she also signals her knowledge of the rules of fashion and her strategies for coping with them—which requires a set of inputs that are much harder to fake. With fashion layered into the mix, men can now tell something about a woman's alertness to social conventions and the world around her, about her problem-solving skills and about the financial resources she brings to the game. (If those financial resources are earned by the woman herself, that directly signals a certain degree of fitness; if the financial resources are provided by the woman’s family, well, that at least strongly implies that some fairly fit genes in her family tree, as well as potentially valuable social connections.)

...to fulfill its role in sexual selection as a sincerity-testing handicap, fashion cannot be about simply making women beautiful, despite the fact that designers always portray their craft in this light. Fashion (as opposed to the rag trade) is about creating a rapidly changing set of rules for dressing which are intentionally subtle, complex, and difficult-to-decode. To make fashion work even better as a sincere (i.e., hard to fake) signaling device, designers must create a hierarchy of rules from introductory to expert while also charging increasingly more for the garments necessary to play the game at advanced levels. Making women beautiful (providing positive face and figure cues) is actually a task that fashion deliberately makes more difficult and expensive.

Sounds good and definitely provides some insight into the world of Fashion. 

However, I think there is more to the general imperative than just the sexual signalling in fashion - as Postrel asserts, there are ample situations where we choose to follow the aesthetic imperative for no reason other than the fact that it simply makes *us* feel good.    Holding / playing with cool home appliances and gadgets has an intrinsic benefit for me above and beyond any social standing I gain from others discovering that I've got a GREAT wine bottle opener.   I innately enjoy using it and like the way the brushed metal feels in my hands.  

Now maybe there's some indirect evolutionary effect at play - after all, a male Peacock doesn't consciously understand why he grows an immaculate plume.   And perhaps similarly, the imperative that makes me enjoy nice stuff eventually parlays into sexual selection games.   In this case, the underlying drive that leads to a nice wine bottle opener could also drive me to select other nice things for my apartment which are more visible to others, which does in turn signal fitness, and so on.... 

The logic can get rather deep and circular pretty quickly - but that's precisely what a talented writer and observer of the Human animal like Postrel can and should be untangling for us.