The answer is hostility. All human beings are hostile. They like to quarrel with each other. At times they fight with each other. Some times they kill each others, for silly reason like religious misbeliefs. He can not live with out the society. He becomes insane when kept in solitude. He become insane when he lives in society as well. Few types of monkeys also have some what similar pattern of behaviour. But is is not as much pronounced. The nature has chosen wrong species for evolution, probably.