What's with girls and them being obsessed about being pretty?

[Packersfan]

I'm a guy, so maybe I won't understand. But guys aren't obsessed about looking hansom, so what's with girls being so obsessed about having to be pretty? There are of course those girls on Facebook and Twitter that whine about feeling ugly, and hope that somebody will call them pretty. I've also seen girls tweet that their day was made when someone called them pretty. So I don't mean to be insensitive, I just am wondering why girls feel this way.

[Sissy Sophie]

Most girls like to feel they look good as society has been like this since time began.