Social Organization. Although today the Kuikuru are egalitarian, there are traces of an earlier system of social ranking among them. Thus, to become village chief or a trading-game captain, a man must be anetï, that is, a member of a bilateral "lineage" to which former chiefs belonged. The chief today does little in the way of mobilizing labor. Most activities requiring the cooperation of persons beyond the nuclear family are planned through informal discussion, the organizer of a work party repaying with food and drink those who helped him.
Political Organization. Chieftainship is presently not a strong institution among the Kuikuru. In 1953-1954 the incumbent headman was a quiet individual who played a very small role in village affairs. Another, more vigorous individual, though not an anetï, took over the de facto role of chief. In 1975 there were three Kuikuru chiefs. The oldest served mostly in a ceremonial capacity, for example, when the village engaged in intervillage ceremonies. The next oldest exercised more authority in economic matters, such as the distribution of goods and the mobilization of labor for fish poisoning. The third aneti chose to play no leadership role at all. The Kuikuru tell of past chiefs, like Afukaká, who, because of the strength of his personality, exercised considerably more control of village life than did later chiefs. A recognized chiefly function is to exhort teenage boys and young men to rise early, bathe in the nearby lake, and live up to tribal norms.
Social Control. Scarcely any formal means of social control exists in the Kuikuru village. The chief plays no role in maintaining order or in punishing offenders if norms are violated. However, the Kuikuru are strongly socialized from childhood to be amiable and to refrain from expressing anger. Indeed, fights among men in the village are unknown. A dislike of being thought stingy, quarrelsome, or aggressive keeps village life running smoothly. Allegations of witchcraft within the village are not uncommon, and fear of being thought a witch serves as a strong deterrent against antisocial behavior. This fear, moreover, is well grounded, since at least four village members have been executed as witches over a period of twenty-five years. If a death is suspected as being the result of witchcraft, the father, brother, or son of the victim asks the shaman to ascertain the witch's identity; the deceased's relatives may take it upon themselves to kill the alleged sorcerer. Beyond this, there is no recourse against any offense committed within the village except "bad-mouthing" the guilty party to others.
Conflict. Ever since the upper Xingu Basin was discovered in 1884, the Kuikuru and their immediate neighbors have been at peace with one another. The one incident of violence involving the Kuikuru was their murder, around 1935, of five visiting Yarumá from a now-extinct village of Carib-speaking Indians located east of the Rio Kuluene. Several groups outside the upper Xingu Basin, recognized by the Kuikuru as Ngikogo, have attacked Xinguano villages at various times. These hostile tribes include the Shavante to the east, the Suya to the northeast, the Chukahamay (Mekranotí) to the north, and the Txikão to the west. There is archaeological evidence in the form of defensive trenches to indicate that, centuries ago, warfare was prevalent in the upper Xingu. However, no oral tradition of this survives.