section_path: South America
section_name: South America
paragraph_text: South America
  
  By the first millennium, South America's vast rainforests, mountains, plains, and coasts were the home of millions of people. Estimates vary, but 30–50 million are often given, and 100 million by some estimates. Some groups formed permanent settlements. Among those groups were Chibcha -speaking peoples (" Muisca " or "Muysca"), Valdivia, Quimbaya, Calima, Marajoara culture, and the Tairona. The Muisca of Colombia, postdating the Herrera Period, Valdivia of Ecuador, the Quechuas, and the Aymara of Peru and Bolivia were the four most important sedentary Amerindian groups in South America. Since the 1970s, numerous geoglyphs have been discovered on deforested land in the Amazon rainforest, Brazil, supporting Spanish accounts of complex and ancient Amazonian civilizations, such as Kuhikugu. The Upano Valley sites in present-day eastern Ecuador predate all known complex Amazonian societies.
  
  The theory of pre-Columbian contact across the South Pacific Ocean between South America and Polynesia has received support from several lines of evidence, although solid confirmation remains elusive. A diffusion by human agents has been put forward to explain the pre-Columbian presence in Oceania of several cultivated plant species native to South America, such as the bottle gourd (Lagenaria siceraria) or sweet potato (Ipomoea batatas). Direct archaeological evidence for such pre-Columbian contacts and transport has not emerged. Similarities noted in the names of edible roots in Maori and Ecuadorian languages ("kumari") and Melanesian and Chilean ("gaddu") have been inconclusive.
  
  A 2007 paper published in PNAS put forward DNA and archaeological evidence that domesticated chickens had been introduced into South America via Polynesia by late pre-Columbian times. These findings were challenged by a later study published in the same journal, that cast doubt on the dating calibration used and presented alternative mtDNA analyses that disagreed with a Polynesian genetic origin. The origin and dating remain an open issue. Whether or not early Polynesian–American exchanges occurred, no compelling human-genetic, archaeological, cultural, or linguistic legacy of such contact has turned up.