Uncontacted Amazon tribes

Indians who are considered uncontacted by anthropologists react to a plane flying over their community in the Amazon basin near the Xinane river in Brazil's Acre State, near the border with Peru, March 25, 2014.

Members of the Mashco-Piro tribe observe a group of travelers from across the Alto Madre de Dios river in the Manu National Park in the Amazon basin of southeastern Peru, as photographed through a bird scope October 21, 2011. Peru prohibits contact with the Mashco Piro and another dozen "uncontacted" tribes, mainly because their immune systems carry little resistance to common illnesses. REUTERS/Jean-Paul Van Belle

Three members of a previously uncontacted tribe make voluntary contact with a team of researchers (R, edge of photo) from Brazil's National Indian Foundation (FUNAI) on the bank of the Envira river in Aldeia Simpatia, Acre state, June 30, 2014. REUTERS/FUNAI

A ceramic flute made by uncontacted Indians sits on a table after it was found by Cacique Omina of the Madija tribe, in the village called Igarape do Anjo in Brazil's northwestern Acre state, March 12, 2014. REUTERS/Lunae Parracho

Indians who are considered uncontacted by anthropologists react to a plane flying over their community in the Amazon basin near the Xinane river in Brazil's Acre State, near the border with Peru, March 25, 2014. REUTERS/Lunae Parracho

Indians who are considered uncontacted by anthropologists react to a plane flying over their community in the Amazon basin near the Xinane river in Brazil's Acre State, near the border with Peru, March 25, 2014. REUTERS/Lunae Parracho

Indians who are considered uncontacted by anthropologists react to a plane flying over their community in the Amazon basin near the Xinane river in Brazil's Acre State, near the border with Peru, March 25, 2014. REUTERS/Lunae Parracho

Indians who are considered uncontacted by anthropologists react to a plane flying over their community in the Amazon basin near the Xinane river in Brazil's Acre State, near the border with Peru, March 25, 2014. REUTERS/Lunae Parracho

Alberto Flores, a Mascho Piro indigenous who was taken away by hunters from an uncontacted tribe during his childhood, is seen at his home in Diamante, a town near the Alto Madre de Dios River, May 25, 2014.

A view of an area of deforested jungle inside the Ashaninka Indian territory in Brazil's northwestern Acre state, March 25, 2014. Many indigenous groups say that they have seen more and more incursions on their territory from uncontacted tribes. The "Bravos," or "Braves," as uncontacted Indians are called in the region, carry out raids on other villages, putting the communities along the Envira River on permanent alert.

A Machinguenga indigenous woman attends a meeting with government authorities to express their concern about the approach of uncontacted tribes to their village, in Shipetiari, near the Alto Madre de Dios River, in Peru, May 25, 2014. REUTERS/Enrique Castro-Mendivil

Members of an uncontacted Amazon Basin tribe and their dwellings are seen during a flight over the Brazilian state of Acre along the border with Peru, May 2008. REUTERS/Funai-Frente de Protecao Etno-Ambiental Envira

Members of an uncontacted Amazon Basin tribe and their dwellings are seen during a flight over the Brazilian state of Acre along the border with Peru, May, 2008. REUTERS/Funai-Frente de Protecao Etno-Ambiental Envira

Members of an uncontacted Amazon Basin tribe and their dwellings are seen during a flight over the Brazilian state of Acre along the border with Peru, May 2008. REUTERS/Funai-Frente de Protecao Etno-Ambiental Envira

Members of an uncontacted Amazon Basin tribe and their dwellings are seen during a flight over the Brazilian state of Acre along the border with Peru, May, 2008. REUTERS/Funai-Frente de Prote o Etno-Ambiental Envira��