Raoni Metuktire, a leader of the Brazilian indigenous ethnic Kayapo people, reacts at a news conference before a protest during the National Indigenous Mobilization at the Esplanade of Ministries in Brasilia April 14, 2015. Organizers of the mobilization aim to discuss issues of land demarcation and indigenous rights with authorities. REUTERS/Ueslei Marcelino

Kayapo Indians take paddle board lessons during a break in the fourth edition of the Traditional Indian Games of Para, held on Maruda Beach in Marapanim, September 6, 2014. Native Brazilians from 15 different tribes are participating in the event that features traditional sports and runs through September 10. Picture taken September 6, 2014. REUTERS/Paulo Santos (BRAZIL - Tags: SPORT SOCIETY)

A Kayapo Indian takes a dip in the Sao Miguel River during the "Meeting of Traditional Cultures of Chapada dos Veadeiros" in a multiethnic village in Goias July 25, 2012. The annual event, currently in its 12th edition, celebrates Brazilian popular culture and the intersection between the various manifestations of traditional culture around the Midwest and across the country. It lasts from July 20-28. REUTERS/Ueslei Marcelino (BRAZIL - Tags: ENVIRONMENT SOCIETY)

An indigenous woman of the Kaiapo tribe paints a woman during the "Meeting of Traditional Cultures of Chapada dos Veadeiros" in a multiethnic village in Goias July 25, 2012. The annual event, currently in its 12th edition, celebrates Brazilian popular culture and the intersection between the various manifestations of traditional culture around the Midwest and across the country. It lasts from July 20-28. REUTERS/Ueslei Marcelino (BRAZIL - Tags: SOCIETY)

An indigenous child from Kayapo tribe attends first indigenous assembly for the "Rio +20" Conference at Kari-Oca village in Rio de Janeiro June 14, 2012. Indigenous people from around the world are visiting the village for the "Rio +20" United Nations Conference on Sustainable Development that will be held from 20 to 22 June. REUTERS/Ricardo Moraes (BRAZIL - Tags: ENVIRONMENT POLITICS SOCIETY)

Native Brazilians from the Kaiapo tribe play on a river bank near the venue of the Indigenous Nations Games in Porto Nacional, in the Amazonian state of Tocantins, November 10, 2011. Some 1,300 members of different ethnic groups from around Brazil are competing in the event that lasts through November 12. REUTERS/ Paulo Santos (BRAZIL - Tags: SPORT SOCIETY)

Native Brazilians from the Kaiapo tribe play in a river near the venue of the Indigenous Nations Games in Porto Nacional, in the Amazonian state of Tocantins, November 10, 2011. Some 1,300 members of different ethnic groups from around Brazil are competing in the event that lasts through November 12. REUTERS/Paulo Santos (BRAZIL - Tags: SPORT SOCIETY)

Brazilian Indian chief Raoni Txukarramae, the chief of the Amazonian Indian tribe Kaiapo, arrives at the Charles de Gaulle airport in Roissy, near Paris, September 19, 2011 to collect a petition to protest the construction of the Belo Monte hydroelectric dam in the Amazonian Xingu River in Brazil. REUTERS/Benoit Tessier (FRANCE - Tags: POLITICS ENVIRONMENT)

Brazilian Indian chief Raoni Txukarramae, the chief of the Amazonian Indian tribe Kaiapo, arrives at the Charles de Gaulle airport in Roissy, near Paris, September 19, 2011 to collect a petition to protest the construction of the Belo Monte hydroelectric dam in the Amazonian Xingu River in Brazil. REUTERS/Benoit Tessier (FRANCE - Tags: POLITICS ENVIRONMENT)

Brazilian Indian chief Raoni Txukarramae, the chief of the Amazonian Indian tribe Kaiapo, arrives at the Charles de Gaulle airport in Roissy, near Paris, September 19, 2011 to collect a petition to protest the construction of the Belo Monte hydroelectric dam in the Amazonian Xingu River in Brazil. REUTERS/Benoit Tessier (FRANCE - Tags: POLITICS ENVIRONMENT)

Brazilian Indian chief Raoni Txukarramae, the chief of the Amazonian Indian tribe Kaiapo, arrives at the Charles de Gaulle airport in Roissy, near Paris, September 19, 2011 to collect a petition to protest the construction of the Belo Monte hydroelectric dam in the Amazonian Xingu River in Brazil. REUTERS/Benoit Tessier (FRANCE - Tags: POLITICS ENVIRONMENT)

Brazilian Indian chief Raoni Txukarramae, the chief of the Amazonian Indian tribe Kaiapo, arrives at the Charles de Gaulle airport in Roissy, near Paris, September 19, 2011 to collect a petition to protest the construction of the Belo Monte hydroelectric dam in the Amazonian Xingu River in Brazil. REUTERS/Benoit Tessier (FRANCE - Tags: POLITICS ENVIRONMENT)

Brazilian Indian chief Raoni Txukarramae, the chief of the Amazonian Indian tribe Kaiapo, arrives at the Charles de Gaulle airport in Roissy, near Paris, September 19, 2011 to collect a petition to protest the construction of the Belo Monte hydroelectric dam in the Amazonian Xingu River in Brazil. REUTERS/Benoit Tessier (FRANCE - Tags: POLITICS ENVIRONMENT)

A man with his face painted like a Kaiapo Indian tribe warrior attends the "Meeting of Traditional Cultures of Chapada dos Veadeiros" in Goias July 24, 2011. The annual event, currently in its 11th edition, celebrates Brazilian popular culture and the intersection between the various manifestations of traditional culture around the Midwest and across the country. It lasts from July 22-30. REUTERS/Ueslei Marcelino (BRAZIL - Tags: SOCIETY)

Kayapo Indians stand in a line during a ritual dance in a multiethnic village during the Meeting of Traditional Cultures of Chapada dos Veadeiros in Goias July 23, 2011. The meeting is a celebration of Brazilian popular culture and the intersection between the various manifestations of traditional culture around the midwest and across the country. Picture taken July 23, 2011. REUTERS/Ueslei Marcelino (BRAZIL - Tags: SOCIETY)

A Kayapo boy with traditional body paint and piercing is seen at his home the day before the start of the "Expedicionarios da Saude" (Brazilian Health Expeditions), in the Kikretum community in Sao Felix, northern Brazil, April 21, 2011. Twice a year, volunteer doctors build a mobile hospital to provide clinical and surgical treatments for indigenous tribes and residents from different parts of the Amazon rainforest. Picture taken April 21. REUTERS/Ricardo Moraes (BRAZIL - Tags: HEALTH SOCIETY)

A Kayapo child waits outside the hospital of the "Expedicionarios da Saude" (Brazilian Health Expeditions), in the Kikretum community in Sao Felix, northern Brazil, April 24, 2011. Twice a year, volunteer doctors build a mobile hospital to provide clinical and surgical treatments for indigenous tribes and residents from different parts of the Amazon rainforest. Picture taken April 24. REUTERS/Ricardo Moraes (BRAZIL - Tags: HEALTH SOCIETY)

Kayapo youths play soccer on the fourth day of the "Expedicionarios da Saude" (Brazilian Health Expeditions), in the Kikretum community in Sao Felix, northern Brazil, April 24, 2011. Twice a year, volunteer doctors build a mobile hospital to provide clinical and surgical treatments for indigenous tribes and residents from different parts of the Amazon rainforest. Picture taken April 24. REUTERS/Ricardo Moraes (BRAZIL - Tags: HEALTH SOCIETY)

A member of the "Expedicionarios da Saude" (Brazilian Health Expeditions) plays with a Kayapo child on the last day of the visit, in the Kikretum community in Sao Felix, northern Brazil, April 29, 2011. Twice a year, volunteer doctors build a mobile hospital to provide clinical and surgical treatments for indigenous tribes and residents from different parts of the Amazon rainforest. Picture taken April 29. REUTERS/Ricardo Moraes (BRAZIL - Tags: HEALTH SOCIETY)

A group of native Kayapos stand at the edge of a river near the medical center built by "Expedicionarios da Saude" (Brazilian Health Expeditions), in the Kikretum community in Sao Felix, northern Brazil, April 28, 2011. Twice a year, volunteer doctors build a mobile hospital to provide clinical and surgical treatments for indigenous tribes and residents from different parts of the Amazon rainforest. Picture taken April 28. REUTERS/Ricardo Moraes (BRAZIL - Tags: HEALTH SOCIETY)

A Kayapo girl hides behind a stuffed doll outside the medical center built by "Expedicionarios da Saude" (Brazilian Health Expeditions), in the Kikretum community in Sao Felix, northern Brazil, April 28, 2011. Twice a year, volunteer doctors build a mobile hospital to provide clinical and surgical treatments for indigenous tribes and residents from different parts of the Amazon rainforest. Picture taken April 28. REUTERS/Ricardo Moraes (BRAZIL - Tags: HEALTH SOCIETY)

Traditional accessories are pictured on a Kayapo man before a dance for members of the "Expedicionarios da Saude" (Brazilian Health Expeditions) during an appreciation ceremony on the last day of a medical expedition to the Kikretum community in Sao Felix, northern Brazil, April 29, 2011. The Brazilian Health Expeditions organization conducted a medical expedition to the area with volunteer doctors that twice a year build a mobile hospital to provide clinical and surgical treatment for indigenous tribes and residents from different parts of the Amazonian rainforest. Members of the expedition examined 1,141 medical cases and performed 73 surgeries. REUTERS/Ricardo Moraes (BRAZIL - Tags: SOCIETY HEALTH)

Kayapo women dance for members of the "Expedicionarios da Saude" (Brazilian Health Expeditions) to show their appreciation during a ceremony on the last day of the medical expedition to the Kikretum community in Sao Felix, northern Brazil, April 29, 2011. The Brazilian Health Expeditions organization conducted a medical expedition to the area with volunteer doctors that twice a year build a mobile hospital to provide clinical and surgical treatment for indigenous tribes and residents from different parts of the Amazonian rainforest. Members of the expedition examined 1,141 medical cases and performed 73 surgeries. REUTERS/Ricardo Moraes (BRAZIL - Tags: SOCIETY HEALTH IMAGES OF THE DAY)

A Kayapo girl holds her doll, which is decorated with the Kayapo's traditional face paint, on the eighth day of a medical expedition of the "Expedicionarios da Saude" (Brazilian Health Expeditions) in the Kikretum community in Sao Felix, northern Brazil April 28, 2011. The "Expedicionarios da Saude" is currently on a medical expedition to the area. Twice a year, volunteer doctors would build a mobile hospital to provide clinical and surgical treatments for indigenous tribes and residents from different parts of the Amazonian Rainforest. REUTERS/Ricardo Moraes (BRAZIL - Tags: HEALTH SOCIETY)

Kwykyti Kayapo, 63, wears sunglasses days after his cataract surgery during a medical expedition by the "Expedicionarios da Saude" (Brazilian Health Expeditions) in the Kikretum community in Sao Felix, northern Brazil April 28, 2011. The "Expedicionarios da Saude" is currently on a medical expedition to the area. Twice a year, volunteer doctors would build a mobile hospital to provide clinical and surgical treatments for indigenous tribes and residents from different parts of the Amazonian Rainforest. REUTERS/Ricardo Moraes (BRAZIL - Tags: HEALTH SOCIETY HEADSHOT)

A Kayapo man makes handicrafts on the eighth day of a medical expedition of the "Expedicionarios da Saude" (Brazilian Health Expeditions) in the Kikretum community in Sao Felix, northern Brazil April 28, 2011. The "Expedicionarios da Saude" is currently on a medical expedition to the area. Twice a year, volunteer doctors would build a mobile hospital to provide clinical and surgical treatments for indigenous tribes and residents from different parts of the Amazonian Rainforest. REUTERS/Ricardo Moraes (BRAZIL - Tags: HEALTH SOCIETY IMAGES OF THE DAY)

A member of the "Expedicionarios da Saude" (Brazilian Health Expeditions) (R) plays with a Kayapo baby on the seventh day of their medical expedition in the Kikretum community in Sao Felix, northern Brazil April 27, 2011. The "Expedicionarios da Saude" (Brazilian Health Expeditions) organization is currently on a medical expedition to the area with volunteer doctors that twice a year build a mobile hospital to provide clinical and surgical treatment for indigenous tribes and residents from different parts of the Amazonian Rainforest. REUTERS/Ricardo Moraes (BRAZIL - Tags: HEALTH SOCIETY)

A Kayapo woman, wearing a traditional dress, has traditional body paint applied on her in front of her house on the seventh day of a medical expedition by the "Expedicionarios da Saude" (Brazilian Health Expeditions) in the Kikretum community in Sao Felix, northern Brazil April 27, 2011. The "Expedicionarios da Saude" (Brazilian Health Expeditions) organization is currently on a medical expedition to the area with volunteer doctors that twice a year build a mobile hospital to provide clinical and surgical treatment for indigenous tribes and residents from different parts of the Amazonian Rainforest. The tradition of their dresses began when a naked Kayapo woman, who went to the city looking for medical attention, was presented with a dress by an old lady. Ever since, the rest of the community of Kayapo women in the Para state now wear similar dresses, according to the locals. REUTERS/Ricardo Moraes (BRAZIL - Tags: HEALTH SOCIETY)

A Kayapo woman, wearing a traditional dress, poses in front of her house on the seventh day of a medical expedition by the "Expedicionarios da Saude" (Brazilian Health Expeditions) in the Kikretum community in Sao Felix, northern Brazil April 27, 2011. The "Expedicionarios da Saude" (Brazilian Health Expeditions) organization is currently on a medical expedition to the area with volunteer doctors that twice a year build a mobile hospital to provide clinical and surgical treatment for indigenous tribes and residents from different parts of the Amazonian Rainforest. The tradition of their dresses began when a naked Kayapo woman, who went to the city looking for medical attention, was presented with a dress by an old lady. Ever since, the rest of the community of Kayapo women in the Para state now wear similar dresses, according to the locals. REUTERS/Ricardo Moraes (BRAZIL - Tags: HEALTH SOCIETY)

Kypato Kayapo, chief of Kayapo tribe from the Aukre community, receives post-cataract surgery ophthalmologic attention on the seventh day of the "Expedicionarios da Saude" (Brazilian Health Expeditions) medical expedition in the Kikretum community in Sao Felix, northern Brazil, April 27, 2011. The "Expedicionarios da Saude" is currently on a medical expedition to the area. Twice a year, volunteer doctors would build a mobile hospital to provide clinical and surgical treatments for indigenous tribes and residents from different parts of the Amazonian Rainforest. REUTERS/Ricardo Moraes (BRAZIL - Tags: HEALTH SOCIETY IMAGES OF THE DAY)

A Kayapo woman paints her daughter in traditional body ink on the sixth day of a medical expedition of the "Expedicionarios da Saude" (Brazilian Health Expeditions) in the Kikretum community in Sao Felix, northern Brazil April 26, 2011. The "Expedicionarios da Saude" organization is currently on a medical expedition to the area with volunteer doctors that twice a year build a mobile hospital to provide clinical and surgical treatment for indigenous tribes and residents from different parts of the Amazonian rainforest. REUTERS/Ricardo Moraes (BRAZIL - Tags: HEALTH SOCIETY)

A Kayapo woman is seen with her children on the Fresco river banks on the sixth day of a medical expedition of the "Expedicionarios da Saude" (Brazilian Health Expeditions) in Kikretum community in Sao Felix, northern Brazil April 26, 2011. The "Expedicionarios da Saude" organization is currently on a medical expedition to the area with volunteer doctors that twice a year build a mobile hospital to provide clinical and surgical treatment for indigenous tribes and residents from different parts of the Amazonian Rainforest. REUTERS/Ricardo Moraes (BRAZIL - Tags: HEALTH SOCIETY)

A Kayapo man, receives attention after a surgery, at his house on the sixth day of a medical expedition of the "Expedicionarios da Saude" (Brazilian Health Expeditions) in Kikretum community in Sao Felix, northern Brazil April 26, 2011. The organization is currently on a medical expedition to the area with volunteer doctors that twice a year build a mobile hospital to provide clinical and surgical treatment for indigenous tribes and residents from different parts of the Amazonian Rainforest. REUTERS/Ricardo Moraes (BRAZIL - Tags: HEALTH SOCIETY)

A Kayapo child does inhalation on the sixth day of a medical expedition of the "Expedicionarios da Saude" (Brazilian Health Expeditions) in Kikretum community in Sao Felix, northern Brazil April 26, 2011. The organization is currently on a medical expedition to the area with volunteer doctors that twice a year build a mobile hospital to provide clinical and surgical treatment for indigenous tribes and residents from different parts of the Amazonian Rainforest. REUTERS/Ricardo Moraes (BRAZIL - Tags: HEALTH SOCIETY IMAGES OF THE DAY)

A Kayapo woman carries bananas in Sao Felix, northern Brazil April 25, 2011. The "Expedicionarios da Saude" (Brazilian Health Expeditions) organization is currently on a medical expedition to the area with volunteer doctors that twice a year build a mobile hospital to provide clinical and surgical treatment for indigenous tribes and residents from different parts of the Amazonian rainforest. REUTERS/Ricardo Moraes (BRAZIL - Tags: HEALTH SOCIETY)

Kayapo children play on the fifth day of a medical expedition of the "Expedicionarios da Saude" (Brazilian Health Expeditions) in the Kikretum community in Sao Felix, northern Brazil April 25, 2011. The "Expedicionarios da Saude"organization is currently on a medical expedition to the area with volunteer doctors that twice a year build a mobile hospital to provide clinical and surgical treatment for indigenous tribes and residents from different parts of the Amazonian rainforest. REUTERS/Ricardo Moraes (BRAZIL - Tags: HEALTH SOCIETY)

A Kayapo woman carries bananas in Sao Felix, northern Brazil April 25, 2011. The "Expedicionarios da Saude" (Brazilian Health Expeditions) organization is currently on a medical expedition to the area with volunteer doctors that twice a year build a mobile hospital to provide clinical and surgical treatment for indigenous tribes and residents from different parts of the Amazonian rainforest. REUTERS/Ricardo Moraes (BRAZIL - Tags: HEALTH SOCIETY)

Kayapo people from the Krokaimoro community arrive at the Kokretum community during a medical expedition by the "Expedicionarios da Saude" (Brazilian Health Expeditions) in Sao Felix, northern Brazil April 24, 2011. The "Expedicionarios da Saude" (Brazilian Health Expeditions) organization is currently on a medical expedition to the area with volunteer doctors that twice a year build a mobile hospital to provide clinical and surgical treatment for indigenous tribes and residents from different parts of the Amazonian Rainforest. REUTERS/Ricardo Moraes (BRAZIL - Tags: SOCIETY HEALTH)

Girls from Kayapo tribe play soccer on the fourth day of a medical expedition of the "Expedicionarios da Saude" (Brazilian Health Expeditions) in Kikretum community in Sao Felix, northern Brazil April 24, 2011. The "Expedicionarios da Saude" organization is currently on a medical expedition to the area with volunteer doctors that twice a year build a mobile hospital to provide clinical and surgical treatment for indigenous tribes and residents from different parts of the Amazonian Rainforest. REUTERS/Ricardo Moraes (BRAZIL - Tags: SOCIETY HEALTH SPORT SOCCER)

Kwykyti, 63, from Kayapo tribe wears a pair of sunglasses as he walks with his wife after a cataract surgery during the third day of a medical expedition of the "Expedicionarios da Saude" (Brazilian Health Expeditions) in Kikretum community in Sao Felix, northern Brazil April 23, 2011. The organization is currently on a medical expedition to the area with volunteer doctors that twice a year build a mobile hospital to provide clinical and surgical treatment for indigenous tribes and residents from different parts of the Amazonian Rainforest. REUTERS/Ricardo Moraes (BRAZIL - Tags: SOCIETY HEALTH)

A child from Kayapo tribe with traditional face paint and earrings is seen during the third day of a medical expedition of the "Expedicionarios da Saude" (Brazilian Health Expeditions) in Kikretum community in Sao Felix, northern Brazil April 23, 2011. The organization is currently on a medical expedition to the area with volunteer doctors that twice a year build a mobile hospital to provide clinical and surgical treatment for indigenous tribes and residents from different parts of the Amazonian Rainforest. REUTERS/Ricardo Moraes (BRAZIL - Tags: SOCIETY HEALTH)

A man from Kayapo tribe wears a pair of sunglasses after a cataract surgery during the third day of a medical expedition of the "Expedicionarios da Saude" (Brazilian Health Expeditions) in Kikretum community in Sao Felix, northern Brazil April 23, 2011. The organization is currently on a medical expedition to the area with volunteer doctors that twice a year build a mobile hospital to provide clinical and surgical treatment for indigenous tribes and residents from different parts of the Amazonian Rainforest. REUTERS/Ricardo Moraes (BRAZIL - Tags: SOCIETY HEALTH IMAGES OF THE DAY)

A child from Kayapo tribe eats biscuits on the second day of a medical expedition of the "Expedicionarios da Saude" (Brazilian Health Expeditions) in Kikretum community in Sao Felix, northern Brazil April 22, 2011. The "Expedicionarios da Saude" (Brazilian Health Expeditions) organization is currently on a medical expedition to the area with volunteer doctors that twice a year build a mobile hospital to provide clinical and surgical treatment for indigenous tribes and residents from different parts of the Amazonian rainforest. REUTERS/Ricardo Moraes (BRAZIL - Tags: SOCIETY HEALTH ENVIRONMENT)

A man from Kayapo tribe observes an Arara in front of his house on the second day of a medical expedition of the "Expedicionarios da Saude" (Brazilian Health Expeditions) in Kikretum community in Sao Felix, northern Brazil April 22, 2011. The "Expedicionarios da Saude" (Brazilian Health Expeditions) organization is currently on a medical expedition to the area with volunteer doctors that twice a year build a mobile hospital to provide clinical and surgical treatment for indigenous tribes and residents from different parts of the Amazonian Rainforest. REUTERS/Ricardo Moraes (BRAZIL - Tags: ENVIRONMENT SOCIETY HEALTH ANIMALS)

A boy of Kayapo tribe plays in front of his house on the second day of a medical expedition of the "Expedicionarios da Saude" (Brazilian Health Expeditions) in Kikretum community in Sao Felix, northern Brazil April 22, 2011. The "Expedicionarios da Saude" (Brazilian Health Expeditions) organization is currently on a medical expedition to the area with volunteer doctors that twice a year build a mobile hospital to provide clinical and surgical treatment for indigenous tribes and residents from different parts of the Amazonian Rainforest. REUTERS/Ricardo Moraes (BRAZIL - Tags: ENVIRONMENT SOCIETY HEALTH)

A boy of Kayapo tribe stands at the entrance of his house on the second day of a medical expedition of the "Expedicionarios da Saude" (Brazilian Health Expeditions) in Kikretum community in Sao Felix, northern Brazil April 22, 2011. The "Expedicionarios da Saude" (Brazilian Health Expeditions) organization is currently on a medical expedition to the area with volunteer doctors that twice a year build a mobile hospital to provide clinical and surgical treatment for indigenous tribes and residents from different parts of the Amazonian Rainforest. REUTERS/Ricardo Moraes (BRAZIL - Tags: ENVIRONMENT SOCIETY HEALTH)

Girls from the Kayapo tribe pose for pictures on the first day of a medical expedition by the "Expedicionarios da Saude" (Brazilian Health Expeditions) in Kikretum community in Sao Felix, northern Brazil, April 21, 2011. The "Expedicionarios da Saude" (Brazilian Health Expeditions) organization is currently on a medical expedition to the area with volunteer doctors that twice a year build a mobile hospital to provide clinical and surgical treatment for indigenous tribes and residents from different parts of the Amazonian rainforest. REUTERS/Ricardo Moraes (BRAZIL - Tags: HEALTH SOCIETY)

A boy from the Kayapo tribe, with body paintings and traditional piercing, is seen on the first day of a medical expedition of the "Expedicionarios da Saude" (Brazilian Health Expeditions) in Kikretum community in Sao Felix, northern Brazil April 21, 2011. The "Expedicionarios da Saude" (Brazilian Health Expeditions) organization is currently on a medical expedition to the area with volunteer doctors that twice a year build a mobile hospital to provide clinical and surgical treatment for indigenous tribes and residents from different parts of the Amazonian rainforest. REUTERS/Ricardo Moraes (BRAZIL - Tags: HEALTH SOCIETY)

A baby from the Kayapo tribe reacts on the first day of a medical expedition by the "Expedicionarios da Saude" (Brazilian Health Expeditions) in Kikretum community in Sao Felix, northern Brazil, April 21, 2011. The "Expedicionarios da Saude" (Brazilian Health Expeditions) organization is currently on a medical expedition to the area with volunteer doctors that twice a year build a mobile hospital to provide clinical and surgical treatment for indigenous tribes and residents from different parts of the Amazonian Rainforest. REUTERS/Ricardo Moraes (BRAZIL - Tags: HEALTH SOCIETY IMAGES OF THE DAY)

A member of the Kayapo tribe undergoes an eye examination on the first day of a medical expedition of the "Expedicionarios da Saude" (Brazilian Health Expeditions) in Kikretum community in Sao Felix, northern Brazil, April 21, 2011. The "Expedicionarios da Saude" (Brazilian Health Expeditions) organization is currently on a medical expedition to the area with volunteer doctors that twice a year build a mobile hospital to provide clinical and surgical treatment for indigenous tribes and residents from different parts of the Amazonian Rainforest. REUTERS/Ricardo Moraes (BRAZIL - Tags: HEALTH SOCIETY)

Kwykyti, 63, from Kayapo tribe receives medical attention during the second day of a medical expedition of the "Expedicionarios da Saude" (Brazilian Health Expeditions) in Kikretum community in Sao Felix, northern Brazil April 22, 2011. The "Expedicionarios da Saude" (Brazilian Health Expeditions) organization is currently on a medical expedition to the area with volunteer doctors that twice a year build a mobile hospital to provide clinical and surgical treatment for indigenous tribes and residents from different parts of the Amazonian Rainforest. REUTERS/Ricardo Moraes (BRAZIL - Tags: ENVIRONMENT SOCIETY HEALTH)

Canadian film director James Cameron shakes hands with leader Raoni Txucarramae of the Kaiapo indigenous tribe after he spoke about the construction of the Belo Monte dam along the Xingu River, during the Global Sustainability Forum in Manaus, March 25, 2011. The second edition of the forum brought together political, business and environmental leaders to discuss the sustainability of the Amazon, according to the organization's website. Picture taken March 25, 2011. REUTERS/Bruno Kelly-A Critica (BRAZIL - Tags: ENVIRONMENT POLITICS ENTERTAINMENT BUSINESS)

Canadian film director James Cameron listens as leader Raoni Txucarramae of the Kaiapo indigenous tribe speaks about the construction of the Belo Monte dam along the Xingu River, during the Global Sustainability Forum in Manaus, March 25, 2011. The second edition of the forum brought together political, business and environmental leaders to discuss the sustainability of the Amazon, according to the organization's website. Picture taken March 25, 2011. REUTERS/Bruno Kelly-A Critica (BRAZIL - Tags: ENVIRONMENT POLITICS ENTERTAINMENT BUSINESS IMAGES OF THE DAY)

Chief Raoni of the Caiapo tribe from the Amazon basin demonstrates against the construction of the planned Belo Monte hydroelectric dam, in Brasilia February 8, 2011. Proposed to be built along the Xingu River in the state of Para, the dam would be the world's third largest at planned capacity, though environmentalists and native Brazilians have raised concerns that the project may displace indigenous tribes and damage the environment. REUTERS/Ueslei Marcelino (BRAZIL - Tags: ENVIRONMENT POLITICS HEADSHOT ENERGY)

Members of Brazil's Kaiapo nation dance during the first day of competition in the Indigenous Nations' Games in Pagagominas, northern Brazil November 3, 2009. Some 600 Brazilian Indians from 29 ethnic groups will compete in sporting events in the tenth edition of the games. REUTERS/Paulo Santos (BRAZIL)

Members of Brazil's Kaiapo nation attend the first day of competition in the Indigenous Nations' Games in Pagagominas, north Brazil November 3, 2009. Some 600 Brazilian Indians from 29 ethnic groups will compete in sporting events in the tenth edition of the games. REUTERS/Paulo Santos (BRAZIL SOCIETY)

A member of Brazil's Kaiapo nation watches the first day of competition in the Indigenous Nations' Games in Pagagominas, northern Brazil November 3, 2009. Some 600 Brazilian Indians from 29 ethnic groups will compete in sporting events in the tenth edition of the games. REUTERS/Paulo Santos (BRAZIL SOCIETY)

Members of Brazil's Kaiapo nation dance during the Indigenous Nations' Games in Pagagominas, northern Brazil November 3, 2009. Some 600 Brazilian Indians from 29 ethnic groups will compete in sporting events in the tenth edition of the games. REUTERS/Paulo Santos (BRAZIL SOCIETY)

Members of Brazil's Kaiapo nation compete in a tug of war during the Indigenous Nations' Games in Pagagominas, north Brazil November 3, 2009. Some 600 Brazilian Indians from 29 ethnic groups will compete in sporting events for the tenth edition of the games. REUTERS/Paulo Santos (BRAZIL SOCIETY IMAGES OF THE DAY)

Kaiapo Indians listen to a speech by Venezuelan President Hugo Chavez during an assembly with Para State leaders in Belem, March 27, 2008. Chavez signed agreements of cooperation with Governor Ana Julia Carepa. REUTERS/Paulo Santos (BRAZIL)