There are wars in the Middle East and Africa, terrorism across the globe, and violent crime in the United States. Why would this be the case unless humans are by nature an aggressive species? It also seems that men are more aggressive than women. Most murderers are male, most rapists are male, and most people in prisons are male. Why would this be the case unless men were naturally more violent than women? It has to be true that at our core we indeed evolved into aggressive, big-brained apes (or at least men did). If it were not for laws, rules, and the constraints of society the law of the jungle—nature red in tooth and claw—would rule the day. Right? Wrong.