Are We Really That Two Faced?

So, an interesting topic came up Wednesday of last week while I was doing my weekly show on Hot 977. I was told that women work very well together, however, we don't like each other. I can't say that I was surprised by this comment. I've certainly witnessed this type of behavior and may have even been a culprit in acting this way, too. For instance, a new girl just got hired at work. She walks in wearing her nice pencil skirt, button down blouse, and heels with her head held high. She walks right past you and your group of friends at work and doesn't speak. Instantly, you take a dislike to her. "I mean, really, who does she think she is? She hasn't even been here a week yet. She thinks she's too much." You and your friends might say to each other. Or perhaps you have a crush on a guy you've seen and conversed with at this nice little spot you frequent and one day you see him smiling and talking with an attractive girl. Suddenly, she's the target of all your negative energy and gossip. Or maybe you see a girl you grew up with at the grocery store and you plaster on a smile and greet her as if you were ultra excited to see her, but call her a bitch as soon as she walks away. My question is; why? Why do we have such a problem with each other? Why do we smile in each others face then talk badly about each other? Now, let me also say that I know that not all females are this way, BUT I know that a lot of us are. So, what do you think? What causes us to be so distrusting of each other?