Women are supposedly neurotically insecure about their bodies. I'll admit that I am, though I conceal it better than most (I think--does this confession count?). We think our boobs are too big/small and our asses are too this or that and the glossies have a ball every summer before bikini season when we're supposedly at our wits' end about looking like a walrus. But you know what? It really doesn't matter--if you have boobs and an ass, you'll get hit on--only not by that cute artsy guy in the cafe (who is, of course, taken), alas. Men, it seems, really don't see much else--at least, not if my observations of ogling behavior along Kelly Drive is correct.
At this point I'd also put in a statement about what physical features about men attract women, but in this respect there's perilously little consistency. Women are far more slick about how they ogle men, and their tastes are far more divergent: the Chippendales would have you believe that the ideal man is 200 pounds of pure muscle, but the variety of body types available amongst the Hollywood elite would suggest otherwise (personally, I go for the more slightly-built, like Eric McCormack, but I have to admit, seeing Daniel Craig in Casino Royale took my breath away).
All of which suggests that there is no one true body type that's universally beautiful. Some characteristics are appreciated, undoubtedly--ten fingers, ten toes, two eyes, one nose--but if you're reading this odds are you meet someone's expectations of beauty.
So why all the pressure to be thin? Or rather, why, in spite of Marilyn Monroe and the zaftig figures of previous generations, and a resurgence of more normal figures, are women still airbrushed to "perfection" and the figure of a prepubescent boy still considered desirable?
Actually, the real question isn't even why we're still told that we need to look a certain way to be "beautiful". It's why we fall for the line that our bodies, as they are, are not enough--that they must somehow be modified to be beautiful. If you think about it, this is a puzzle: female apes don't feel the need to don high heels and strut their stuff in couture--but I betcha they would if another did it and won the ultimate Darwinian prize: a male.
Which gender self-modifies is irrelevant from this point on. In most species where sexual dimorphism occurs, it's usually the male that gets decked out like a drag queen. Sexual selection is certainly a powerful force when it comes to designing traits that the other gender "likes". But it's not the end of the story. I would suggest that a somewhat more subtle psychological need to be assimilated, especially in social animals (like humans) also plays a key role in why we get gussied up.
That is: women dress up because it makes them more attractive to men. But it also unifies them with other women. Assimilation is not just for the Borg. It makes civilized life possible. And leads to an interesting array of neuroses, like that involving bikinis.