Why always the horrible?

Why is it that we always focus on the horrible things in life rather than the good things? Even our news would rather show the disastorous events than the heart warming events. We hear about drug deals, murders, rapists, assualts, kidnappings, vehicle accidents, etc, etc every day. To this I feel that it is sad. Yes the reason that our news channels tend to do the negative reports is because that's what human beings want to watch. We want to see the horrible things. Why is that we dont want to hear those good heart warming stories of people doing great things for others? Something that might encourage you to do the same for another, or maybe just put a smile on your face. Is it because we want to always have something to complain about? Can we never be content with a day if nothing were to happen in the shady area? Or is it that we want to blame others? Do we want to have other people to look at and scorn so that we can forget what we ourselves have done? So what is it that compells us to go towards the darkening events, rather than listening to the light touching events instead?