Central to the discussion of human social life is an ideal of behavior called ifutisu, a set of ethical statements by which the Kalapalo distinguish Upper Xingu people from all other human beings. In a more general sense, ifutisu can be defined as behavior characterized by a lack of public aggressiveness – for example, avoiding arguing in public and not provoking situations that will make others uncomfortable – and by the practice of generosity – such as hospitality and the willingness to give or share material possessions. The Kalapalo believe that their society’s viability depends upon conforming to this ideal.

The concept of ifutisu extends into virtually every area of social life, applying in varying degrees to relationships among local groups, kinspeople, relatives by marriage, men and women, and even between humans and non-humans. Similarly, the demonstration of ifutisu behavior confers prestige and therefore is important in the allocation of political power. This ideal is manifested in a distinctive behavioral and conceptual complex that the Kalapalo claim distinguishes them from their traditional neighbors.

Before the establishment of the reservation boundaries and permanent contact with Brazilians, the ethnographic situation in the Upper Xingu Basin was complicated by the fact that a number of aggressive tribal groups surrounded this territory and occasionally clashed with its residents. Relationships between the Kalapalo and some of these groups – especially the Jaguma, who lived to the east of the Tanguro River (a tributary of the Upper Kuluene) – were occasionally amicable, but more often they were antagonistic. The Kalapalo call these tribes, and, more generally, any Indians who are not part of Upper Xingu society, aõikogo, “fierce people” (from aõiko, “fierce” or “wild” behavior). This category of “human beings” is conceived primarily in terms of a kind of behavior labeled itsotu, which refers to unpredictable anger and violence. Itsotu behavior is often explicitly contrasted with peaceful, generous behavior called ifutisu, which the Kalapalo consider to be an important distinctive feature of the category “people of Upper Xingu society” (kuge, “human being”).

The second important means by which the Kalapalo distinguish kuge from other human beings is a set of dietary practices that reflect ifutisu. The most significant aspect of this is a system in which “living things” (ago) are classified according to whether they are eaten or not eaten by people of the Upper Xingu. The Kalapalo generally reject animals they call õene, land animals that are furred, and eat those they call kaõa, water creatures (especially fish). In addition to this general principle, there are specific restrictions for persons in life crisis situations, particularly adolescents. The importance of the dietary system is underscored by the Kalapalo idea that one’s external physical appearance is a mark of one’s internal feelings, so that physical beauty, accomplished by obeying the food restrictions and medical practices is a sign of moral beauty. In Kalapalo myths, pubescent girls and boys often enact roles of moral perfection that contrast with the bad behavior of their adult relations.