Humanity has evolved from pack hunters with unique hunting capabilities, but essentially our behavior remains the same. Although many have denied that animals have feelings and any kind of consciousness, the evidence for such things is rather substantial as well as remarkably clear and self-evident among our closest cousins, the chimpanzees. For the purpose of focusing this discussion, I will not go into the details of the direct evidence for animals having some kind of consciousness and emotional life. Essentially, pack-hunting societies are organized cultures of hate, which often extensively use guilt and threats to regulate the levels of violence according to the demands of the environment at the time. Whether a particular species of pack hunters utilizes more violence or guilt or threats is, in turn, genetically regulated. Hyenas, for example, are particularly vicious with each other as well as their competition while lions are more laid back. In the case of humans, it has recently been demonstrated that approximately one quarter of the population is genetically predisposed towards more violent behavior if the environment reinforces this predisposition. The strategy of pack hunting societies can be summed up as, "My enemy's enemy is my friend. " Once one enemy is defeated, you turn your attention towards the enemy that helped you defeat them. For example, once done fighting with a rival pack over a kill, hyenas will then turn their attention towards resolving dominance issues within the pack. In the case of human packs, this level of cooperation has been extended to new heights within the animal kingdom. Rather than merely involving cooperation within the pack against competing packs, among humans multiple packs will form temporary coalitions to defeat their common enemies. The more hierarchal and competitive the pack society, the more vicious and psychopathically guilt free the individuals within the pack will be. The less competitive, the more they rely on guilt to avoid physical confrontation. However, if enough guilt or violence is brought to bear it will result in a significant trend towards the physical adaptation of the pack becoming more vicious. Under the stress of sustained or extreme violence the physiology of the individual members of the pack changes in a process psychologists currently refer to in humans as “Post Traumatic Stress Disorder.” This causes the parts of the brain that regulate impulse control and positive feelings to shrink. If the stress is sustained from early childhood on, or over a protracted period of time, the physiological changes become permanent within the individual. Such sustained stress and violence is counter-productive to the long-term health and reproductive capacity of animals. It reduces the effectiveness of the immune system, causes mating to become a risky venture, and in general requires the animal to constantly be on guard and expending energy. If the entire pack is exposed to such stresses over multiple generations it will by default select for those individuals better adapted genetically to cope with the physiological and psychological demands of the situation. Notably, the genetic and psychological predispositions of the pack are not synonymous with human destiny. Human societies have existed which have little resemblance to the usual pack hunting societies, however, these have required unique conditions. The language of the !Kung of Africa, for example, does not even possess a word for guilt. Historians estimate that before the white man came and forced them onto a crowded reservation murder, rape, and serious thefts occurred among them perhaps once every four hundred years. After being forced onto a reservation, such criminal behavior obtained the same ubiquitous proportions most societies experience and the !Kung adopted the pervasive use of the concept of guilt. In general, natural selection favors flexibility in species. The more complex the species, the more flexibility is favored and this general rule applies to pack hunters who are widely considered to be among the most complex of animals. Within the next fifty years psychologists have estimated that cures will be found for some eighty percent of all mental illnesses. Understanding humanity’s heritage as pack hunters then, is perhaps essential towards such efforts. Certainly, whether these efforts are as successful as the psychologists hope or not, it appears to be essential towards implementing preventative measures and promoting world Peace.