The typical organization among nomadic hunters, gatherers, and fishers was the band, which, depending on the resources, could be large or very small. Low productivity and the lack of developed transportation prevented the accumulation of a surplus to maintain permanent communities. There were no social or occupational specialists; every family produced its own equipment. Despite these general similarities there was wide diversity in social structure depending on the methods of obtaining food.
The Chono, Alacaluf, and Yámana of the Chilean archipelago were dispersed in elementary family units of father, mother, and children with perhaps an elder or two. These small family bands, if they can be so called, moved from one beach to another. There were no permanent territorial claims to shellfish beds, although individual families repelled others while they were using a particular shellfish bed. Sometimes close relatives or friends would move together briefly, and at times a number of families would gather together to feast on a stranded whale or join in hunting seals or sea lions. The family was also the economic unit among the Guató and, during the dry season, among the Nambikwara. This, of course, does not mean that the people did not visit relatives when circumstances permitted or when certain religious and ceremonial activities demanded.
The hunting of guanaco and rhea among the eastern Yámana and Ona and among the Patagonian and Pampean tribes was more productive when carried out cooperatively by a number of families banded together. Such bands consisted of 40 to 100 persons and had defined hunting territories, which the men defended against trespass. Chieftainship does not appear to have been hereditary but was ceded to a leader able in settling both internal disputes and conflicts between bands.
With the introduction of horses and cattle, a great change took place in the band organization. Horses permitted greater mobility, new techniques of hunting, and much larger bands. The former foot hunters joined into bands ranging from 500 to 1,000 persons. They roamed over ill-defined areas hunting wild cattle and raiding Spanish settlements and other Indians without horses. Each of these bands consisted of a number of lineages under a leader of proven ability; a strong leader might attract a huge following, including members drawn away from other bands. Warfare between bands increased because of uncertainties over rights to territory.
Forest nomads, such as the Guayakí and Sirionó, on the other hand, were matrilineal and matrilocal—that is, an individual traced his ancestry through his mother’s lineage, and a man went to live with his wife’s band. Matrilineal descent and matrilocal residence were associated with the importance of women gathering food.
Although little is known about the social structure of the Chaco tribes in aboriginal times, there appears to have been a contrast between the peoples of the dry western area and the wetter eastern area. Because the people in the west depended on water holes, they were forced to shift camp frequently as holes dried up. The groups nevertheless seem to have claimed territorial rights to gathering, fishing, and hunting areas. With the arrival of the Spaniards and an increase in warfare, the authority of the chiefs was strengthened, although chieftainship was rarely hereditary. In the eastern Chaco, on the other hand, the presence of fish runs in the larger rivers and the practice of fairly productive cultivation permitted the settlements to be larger and less mobile. After acquiring the horse from the Spanish, however, the Caduveo and other Guaycuruan-speaking peoples gave up what little horticulture they practiced and became predatory nomads raiding Spanish settlements, taking cattle, and capturing slaves from more sedentary tribes. Other Chaco tribes, such as the Abipón, Mocoví, Toba, and Lengua, also became horsemen and raiders. These tribes continued to move their camps in search of pasture for their herds of horses and cattle. Incipient class differences based on war honours and wealth appeared.
The Caduveo were outstanding raiders in the Chaco. Although roaming over great areas, the warrior bands always returned to their base settlements, where they had permanent houses and kept their slaves and livestock. The Caduveo also exhibited the clearest form of social stratification, which, although pre-Spanish, crystallized with the coming of the horse and the intensification of warfare. Caduveo society became stratified into nobles, warriors, serfs, and slaves. The nobles were divided into those who inherited their titles and those upon whom titles were bestowed for lifetime only. The warrior class was basically hereditary, but other men demonstrating greatness in war could become members, thereby establishing new hereditary lines. The serfs, who served only the members of the noble class, were from subjugated peoples. The lower class was made up of captured and purchased slaves, who included not only Indians from neighbouring tribes but also mestizos from the Spanish settlements. Slaves could gain their freedom by marrying into the warrior class.