Fear - it's necessary; without it you'd step off a cliff, or do something else really daft that'll end badly.
Definitely fear. It's fear of differences in other people which causes most of the world's conflict.
Fear is what gave snakes venom, tigers agility and humans their brains. We make houses, boundries, forts, weapons, clothes and develop prejudices because we're scared.<br />
When someone screams our swears at u, hits u, they're just scared.
Of the two - FEAR but if I were to choose from all human characteristics in the negative realm - I think the most universal is GREED!