between members of the same group and warfare as hostile action between different groups Contrary to the belief that warfare is a non-holds-barred action aimed at exterminating one's enemies, both feuds and warfare operate according to cultural rules and expectations. For example, we speak of the treatment of prisoners of war according to rules of internal treaties and, also according to treaty, certain kinds of weapons have been banned, and certain targets are regarded as off limits in military aggression. Feuds, conducted according to rules, involve collective, not personal, responsibility. Revenge is often taken against any member of a group In segmentary lineage systems, found among the Nuer of Sudan and the Enga of New Guinea, it is difficult to separate feud and warfare, since sub-clans feud with each other in much the same ways that the larger society does when engaging in warfare against another community It should be remembered that no data exists on human aggression and warfare prior to European expansion. In other words, a clear picture on what tribal or"primitive "warfare actually consist of does not exist. It is thus impossible to accurately assess the impact of western expansion including its own means of conflict and warfare-on local populations anywhere in the world One of the fullest accounts of warfare practiced by a small-scale society is that of the yanomamo Indians of Amazonia, studied by Napoleon Chagnon. There are several levels of hostility amor the Yanomamo, each of them representing a distinct phase in the escalation of conflict but hostilities can terminate at any level. The chest-pounding duel is the most innocuous form of fighting, halfway between a sporting contest and a fight. It can take place between two individual of the same village or, on the occasion of a feast, between the men of two different villages. In a chest-pounding duel, men are paired and take turns striking each other on the pectoral muscle of the chest with a bare fist. Chest-pounding duels arise from accusations of cowardice, stinginess with food, or gossip Chest-pounding may be considered as the antithesis of war, for it provides an alternative to killing. The next level is the side-slapping contest, when the blow is levied with a hand to the side of the body between the ribs and pelvis. duels are formal and are regulated by stringent rules about proper ways to deliver and receive blows These are only slightly more aggressive than chest-pounding. The third level is the club fight, which can also take place within or between villages. Two men attack one another with wooden clubs eight to ten feet long and attempt to hit each other on the skull. Such fights typically arise as a result of arguments over women. The enraged husband challenges his opponent to strike him on the head with a club. He holds his own club vertically, leans against it and exposes his head for his opponent to strike. After he has sustained a blow on the head, he can then deliver one on the opponents skull. But as soon as blood starts to flow, almost everybody rips a pole out of the house frame and joins in the fighting, supporting one or the other of the contestants These contests end when one opponent withdraws The most intensive kind of hostility is the raid, conducted by one village against another, which one could define as warfare. Villages that have a history of being enemies raid one another to take revenge for past homicides. Also, once the relationship between to villages is one of hostility, then a death in one of the villages will be attributed to the malevolent forces sent by shamans in the other village, and raids will eventually take place between them. Even where there is no history of homicides, hostile relations can build from a club fight to raiding if one or