The few remaining Native Americans of Venezuela, the Guianas, and Brazil N of the Amazon are mostly descendants of the Arawaks and the Caribs. A considerable number of seminomadic farmers and hunters survive in the hinterlands of the Guianas and in the basins of the upper Rio Branco and Rio Negro. In most of the Amazon basin, including the tropical regions of E Colombia, Ecuador, Peru, Bolivia, and NE Argentina, as well as in the basin of the Río de la Plata, the surviving Native Americans are mostly of Tupí-Guaraní stock (see Guaraní). Belonging to a separate linguistic stock are the Gê-speaking Native Americans of the eastern highlands of Brazil. Although not materially advanced, the Gê are characterized by a highly complex social organization. The Brazilian Tupí-Guaraní practice a rudimentary form of subsistence agriculture and have not developed an extensive material civilization. Today the Native American population of Brazil is relatively small and scattered in isolated clusters. The Guaraní of Paraguay, on the other hand, are fairly numerous, skilled in minor arts, and play a significant role in the national life. Another tropical-forest Native American group is the Jívaro, once practitioners of head shrinking. The Colorado of W Ecuador are almost extinct but have often been the object of public attention because of their practice of painting their bodies with bright red paint. They are actually of Chibcha stock. The Motilones, who live along the border of Colombia and Venezuela in the marshes and hills W of Lake Maracaibo, have tenaciously resisted assimilation. The other major Native American groups of South America consisted of the nomadic hunters of Patagonia and the fishing people of the islands and fjords of S Chile and Argentina. The Puelches and Tehuelches, tall hunters of the Patagonian tableland, were encountered by early Spanish explorers; these people have virtually disappeared. In the rugged and wet region of the southernmost archipelagoes a dwindling number of Native Americans survive. Frequently called the Fuegians, because of their campsites at Tierra del Fuego, the Ona, Yahgan, and Alacaluf survive by hunting and fishing. The canoe is the chief mode of transportation of the Yahgan and the Alacaluf, and their social organizations are not as advanced as those of other Native American groups.