Contrary to many news stories, the isolated group has actually been monitored from a distance for decades, past and current Brazilian government officials say.
No one, however, is known to have had a face-to-face meeting with the nomadic tribe, which lives along the Peru-Brazil border. And no one knows how much, if anything, these rain forest people know about the outside world.
The tribe—whose name remains unknown—was first discovered by outsiders around 1910, according to José Carlos Meirelles, an official with Brazil's Indian-protection agency (FUNAI).
It was Meirelles who released the photos on May 29 through the indigenous-rights advocacy group Survival International.
Meirelles said he made the photos public to prove the group exists. Activist and former FUNAI president Sydney Possuelo agreed that—amid development and doubt over the existence of such tribes—it was necessary to publish them.
Taken in May, the photos became a sensation and spurred debate over how best to protect isolated tribes. Many indigenous-rights advocates see such groups as under threat from oil, gas, and logging interests that covet in the Indians' resource-rich homelands.
Despite such apparent threats, the recently photographed group's population has nearly doubled in the last twenty years, Meirelles added.
A few things are known about the enigmatic people, Meirelles said.
They have shaved foreheads but long hair. They plant cotton—or perhaps find it growing in the jungle—and spin it into cloth for skirts.
For the men, the women make cotton belts and headbands. They also make hammocks that are strung below huts covered by thick, thatched-palm roofs. "They are agriculturalists," Meirelles said. "They have big fields, and they grow cassava, maize, almonds, pumpkin, and various types of potato, papaw, yams, and banana."
But both Possuelo and Meirelles said the tribe could have taboos against certain foods, making it impossible to describe their diet with exactitude.
Hard to Photograph
Along with the nomadic tribe, there are three sedentary groups living in the same vast region, Meirelles said. Each group lives at least 150 kilometers (93 miles) from its nearest neighbors.
The nomadic tribe was especially hard to photograph, Meirelles said.
"When they hear the noise of the plane, they hide in the forest, leaving their communities empty," Meirelles said.
"It seems that something very bad, related to an airplane, happened to them. … I think maybe bombs were thrown at them, or they were shot at," he said.
Keeping a Distant Watch
In 1988 FUNAI surveyed the tribe's region from the air, and Brazilian government scouts have carried out ground expeditions near the edges of the group's territory to demarcate their lands.
Since 1989 Brazil has operated "protection post" on the region's Envira River. There, six state officials keep a careful, protective, and appropriately distant watch, patrolling daily to keep developers from encroaching on the land, Meirelles said.
"To protect these people—after years of doing expeditions on the ground—we managed to determine the territory of these Indians and to demarcate two indigenous territories. And a third is due to be demarcated this year," he said in an email.
The two existing territories—the Alto Tarauacá Indigenous Territory and the Riozinho do Alto Envira Indigenous Territory—together cover about 2,400 square miles (6,250 square
Not everyone is jumping on the uncontacted-tribe bandwagon, especially at a time when indigenous peoples' lands are highly sought after for their natural resources.
In Peru—which is facing illegal logging and heavy oil and gas development in once pristine Amazon regions—top officials have publicly suggested that uncontacted people don't exist.
Similar doubts can be heard in Brazil, ex-FUNAI president Possuelo said.
"Here some people have tried to suggest that we have brought in indigenous groups from other places to claim there are people living in isolation," Possuelo said in a telephone interview.
Current FUNAI official Meirelles objected to suggestions that the group in the recent photos had arrived in Brazil only recently.
"This is not true. They've always lived on the Brazilian side," he said.
"The people coming from Peru are other Indians, from another tribe. Their haircuts and homes are different."
"I Don't Want to Know Any More"
Robert L. Carneiro is an anthropologist at the American Museum of Natural History. In an earlier interview with National Geographic News, he said that the bamboo belts and headbands apparently worn by the men in the photos make him think the people could be belong to the Aruak tribe, which he studied in 1960 and 1961.
Possuelo, former head of FUNAI, said it's possible the group in the photos are Aruak. But, he added, they could be from other tribes in the area.
"The point is that, because we've never contacted them, we just don't know anything about them," he said. "So anything anyone says about them has to be treated as speculation."
Meirelles tries to keep a distance while defending the uncontacted tribe.
"I don't want to know any more about these peoples," he said. "We just want to protect them."