Jealousy

Can anyone explain to me why we all get jealous? Seriously, we do we all want what someone else has? Can't we just live in peace with what we don't have? This is just a topic I can really relate to right now. It's not because I'M jealous of anyone, it's because my friends and I think someone else is jealous of me. For whatever the reason, this person is jealous of me. We really don't understand why people get jealous.

Do we get jealous because we feel emotionally connected to what someone else has? I think that is the case in many situations. I know when I get jealous or envious of someone, it's because they have something that I want for whatever the reason. But, I always have a story of why I want it. If you could really help me on this, I would love to understand why us human beings get J E A L O U S.