This post aims to address Cynic's post.
Vanity and seemingly frivolous actions typically boil down to an individual's self perception of the world around them. (and whatever the society has brainwashed people into what is beautiful)
As simply stated by Cynic, there are two reasons for being vain--self-esteem and self-image. Her definition of self-esteem is having one measure his own self worth by his appearance; while self-image is refers to one being assured of their worth. In short, it's either having yourself assure you, or have others assure you.
However, I think that there is only one reason for vanity-- insecurity. It's all about reassurance of your self worth. As for attracting a mate, that should not be called vanity, as that is a natural thing that all animals do. Vanity is a word that is more to the undesirable side. Since attracting a mate is normal, it's considerably at the equilibrium, and thus not included under vanity.
Now, we have identified the reason for vanity. Insecurity is a dominant feeling in all of us, no matter how well one hides it. It's inborn human nature. We doubt almost everything, be it ourselves or others. We suspect, we are afraid, we want to survive, we are not sure if we are good enough. This is probably residue emotion from when we lived in the wild. We had instincts then, and could count on them. Now humans have lost most of their instincts, the remainder is translated to insecurity, and some to what we call "gut feeling", which most of mankind now do not know how to use. As shown by Malcolm Gladwell in his book "Blink", we can actually deduce alot from just a split second, thus first impressions matter much more to us.
Back to the discussion about insecurity. Insecurity is the result of our loss of instincts, the feeling of being crippled. Humans were suited for the unpredictable wild, as shown by how we still can adapt to different environments quickly.
As for the exceptional few who can't adapt, it's probably because of emotions. As we get further away from the wild, our lives are more predictable, our emotions are much stronger, and we cling onto things more.
Why so? Apes are shown to have emotion (if I remember correctly). They mourn for their dead. But life in the wilderness still goes on, they have to keep going. Their life goes by days. Our life goes by DECADES. We have suppressed the instinct and need to move on. (those who keep harping about the past)
So we have much more time to get emotionally attached to something, and have so little worries about our own future. It's all planned, just like a train track. It's this predictability that causes us mental disturbance. Some are too used to it, such that when something happens, they blame the whole world... Which is not an unfounded thing to do, since it's all of mankind's fault for making things the way they are now.
We forget that tomorrow might not exist, and take things for granted. The more a person is used to a predictable way of life, the more he or she resents when something changes.
Only one who can constantly remind him or her-self that their time is limited, can live in this world without being spiritually scarred.
The more predictable our lives are, the more emotional we are.
I have this little thought here, and would like to side-track for a while. Resentment. That's what I think makes the difference. If there are ghosts, which there probably are, they must have resented in some way or another. That's a reason you rarely see animal ghosts. They know that nature is unpredictable. Not so when they are reared and killed by humans. There's rumors that there's cries of animals slaughtered in abandoned farms.
Back on track. More predictable, more time for emotions. More emotions, more attachments, more confusion, more resentment, more insecurity. Basically more violent emotions that keep chewing on your soul. It's a vicious cycle. Being more insecure, people make things more predictable.
The irony of mankind. Walking to it's own demise is it? Or will everything just escalate to a point of no return? The circle of life... Do we return back to where we started?
No one knows.
But for sure there was a reason why we have such instincts. Straying from the path of nature may not be that good after all... don't you think so?
*This whole theory of mine may be weird, and this post was typed out totally unplanned, so I apologize for its haphazard manner, and its spelling or grammar mistakes if any.*
P.S. *please comment. =) I like hearing others' opinions*