I'm going to go out on a limb and say every culture has them. I'm thinking Africa, Asia, native Indians, even Europe with the Venetian carnival comes to mind. Whether beards and make-up also qualify I'll leave up to you.
The purpose of masks are many, to deceive, to represent, to hide behind. Today, the clothes we wear function as a mask, sometimes to portray a certain image, sometimes to aid our self-esteem, sometimes to separate our private personality from our public persona, and in that respect we're not that different from the cave man with the saber tooth around his neck.
Business men wear suits, why? Because banks and other conservative establishments expect it. Suits communicate you're taking care of your appearance, and you're happy (oh well) to conform to the norm of your field. Some suits are better than others, but basically they're the armor of the contemporary manager. Personally, dressing in a suit influences the way I carry myself, not only as dictated by limited range of motion, but by what the suit represents. I walk a little taller and straighter, I'm a little more aware of what I'm wearing and how it looks, and yes, wearing one makes me feel more confident, professionally.
Women have been known to feel more confident or brazen depending on which underwear they put on. Silk feels sexy. Lace is uncomfortable if you ask me, but it looks nice. Anyway, well-fitting undergarments provide flattering curves, and flattering curves gain attention, and the confidence men and women exude used to directly influence their ability to procreate. To a lesser and more subtle extent, that's still the case today. Research has shown that strippers make more tips and are perceived as more alluring and beautiful during ovulation, and that's not even wearing but taking off their clothes, so I digress.
Creative types don't normally wear suits, and I'd probably count IT-ers into this category, too. I heard a piece on NPR recently that said Silicon Valley is introducing "Formal Friday" to allow people to dress up (as opposed to Casual Friday where jeans make an appearance). No programmer wears a suit, why? They mostly sit in front of a computer and have little outside contact to clients. In this case the image communicated through clothing is, "we're relaxed and comfortable, easy-going!"
Work in the army, police force, firefighting or in health care and you're expected to wear a uniform. Your particular contribution, though highly appreciated and valued, serves the group and therefore the greater good. As part of a team you need to be easily identifiable as to position or rank, but your personality doesn't necessarily play into it.
Do you remember the punk movement of the 70s and 80s, people with spiky green hair scaring pedestrians all over Europe? Or the grunge phase where suddenly it was cool not to wash your hair for weeks? Rebelling against the establishments or their parents turned all of us self-proclaimed individuals into herds of sheep wearing the same things, looking alike. Not wanting to belong to one group makes every generation create their own, and sometimes that persona is put on with a lot of help by peer pressure.
What masks are you wearing every day, and how do they inhibit or support your openness and vulnerability?