Notice at the end of my post I mentioned that I was only providing some gross generalizations and that it's a complicated issue.  I also mentioned that biology plays a HUGE role, a role that is far too often dismissed by most people In my experience.

Waist hip-ratio is one thing that spans cultures, but another factor that's equally important is symmetry.

I think a lot of people just think it's almost entirely society that determines what others find attractive and that's simply not true.  If anything, society (or should I say, those who want to sell us something) simply plays on our *natural* desires and maybe exaggerates them (think fake boobs, makeup, lighting, airbrushing).

Now, desertpear, we have to make a distinction here between "skinny" and "ultra-skinny".  You started to blur the line when you wrote "women in the media".  I don't think the sexy women on Fox News for example can be compared to the Kate Moss's of the world.  If we want to have that discussion, tha's fine, but that wasn't my original intent.

But it's not just supply and demand either.  If the world was filled with tall guys (let's say everyone was 6'2)  I seriously doubt the short guys would suddently be a hot commodity(average height is 5,10 for men BTW).

There's a reason taller guys are sought after that's spanned history and goes back to the caveman days. If marketers made a concerted effort to make short cool, it might have *some* impact but it would be far less successful than a campaign to make a natural, widespread desire even cooler.

And obviously there are evolutionary explanations for why men prefer large breasts. The problem is of course that marketers have raised the bar and with surgery, lighting, super-bras (and finding the women who naturally have these things), etc, although again that applies to men with cut jaws and six-pack abs.  Same thing with darker people with light eyes (it happens but obviously it's less common, but that's why there are contacts, right?).

At any rate, supply and demand is relevant here because in the end, we all lose.  Both men and women, gay and straight.  There really IS a limited supply of people who have ALL of these characteristics (a great waist hip ratio, symmetrical face and body, larger breasts, light eyes and so on) we shouldn't expect to find them very often in every day life.  (Granted, those of you in LA have a better shot than some but still).

Same with men that are tall, dark and handsome (with a chiseled jaw, non-receeding hairline, six-pack, big but not too big, etc.).  But every day we're bombarded by images of this small subset of (biologically) alpha males and females, which tricks us (consciously or not) into thinking that the supply of them is great.  Again, we might know on the surface that's not true, but it does effect us in some way.

And on top of it as I said, surgery, make-up, lighting and airbrushing take these alpha people and make their appearance completely unrealistic in any way for anyone to acheive without these things, and that applies for women *and* men.  Not to mention the fact that people who act or model can usually afford (financially and time wise) to have surgery, or workout all the time, or hire a personal chef/trainer, etc.