Aerial photographs of an isolated tribe in the Brazilian rain forest are yielding a sensational new look at a Neolithic way of life that has all but disappeared from the face of the Earth.

The high-resolution images, taken from a helicopter last week by Brazilian photographer Ricardo Stuckert, offer an unprecedented glimpse of a vibrant indigenous community living in complete isolation in the depths of the Amazon jungle. National Geographic obtained first-time rights from Stuckert to publish a selection.

“I felt like I was a painter in the last century,” Stuckert said, describing his reaction to seeing the natives. “To think that in the 21st century, there are still people who have no contact with civilization, living like their ancestors did 20,000 years ago—it’s a powerful emotion.”

Stuckert’s close-up photographs taken near Brazil’s border with Peru show details about these Indians that had previously escaped the notice of experts, such as their use of elaborate body paint and the way they cut their hair. “We thought they all cut their hair in the same way,” said José Carlos Meirelles, who has worked with and studied Brazil’s indigenous tribes for more than 40 years. “Not true. You can see they have many different styles. Some look very punk.”

The same tribe gained global attention in 2008, when agents from Brazil’s indigenous affairs agency, Fundação Nacional do Índio—known by its acronym, FUNAI—released photographs of tribesmen in red body paint launching arrows at their low-flying airplane. (Learn about how uncontacted tribes emerge.)

The tribe has moved a number of times since that sighting, said Meirelles, a veteran FUNAI scout and expert on the region’s indigenous groups. Meirelles was on last Sunday’s flight, as well as previous missions in 2008 and 2010 that also yielded extraordinary images. “These groups change locations every four years or so,” Meirelles told National Geographic by phone from his home. “They move around. But it’s the same group.”

Stuckert arrived earlier this month in the far western Amazonian state of Acre as part of a yearlong project to photograph indigenous tribes across Brazil. Last Sunday, he boarded a helicopter with Meirelles to visit the jungle outpost of Jordão near the border of Peru. When thunderstorms forced the chopper to make a detour in midflight, the occupants suddenly found themselves flying directly over an isolated settlement of thatched huts carved into the dense jungle. The naked inhabitants were evidently just as surprised, scattering into the surrounding forest at the aircraft’s approach.

The tribe’s initial panic seemed to give way to curiosity by the time the team returned a few hours later for another look. “They seemed more inquisitive than fearful,” Stuckert told National Geographic when reached by phone. “I felt there was a mutual curiosity, on their part and mine.”

The tribe’s apparent well-being was heartening to Meirelles. The people looked well fed and healthy, he said. Plots of corn, manioc, and bananas surrounding the cluster of communal huts—known as a maloca—seemed capable of sustaining as many as 80 to a hundred people. Together with other nearby malocas of the same tribe, Meirelles believes the population exceeds 300.

Equally impressive for Meirelles was the barrage of arrows the tribesmen fired at the helicopter, which he took as a healthy sign of resistance. “They’re messages,” he said. “Those arrows mean 'Leave us in peace. Do not disturb.'”

Unlike other regions of the Brazilian Amazon, the state of Acre enforces strict vigilance over its forests and indigenous inhabitants. The isolated tribes of Acre appear to be safe—for now. But the jungles across the border in Peru are rife with illegal logging crews, gold prospectors, and drug traffickers, posing the kind of threats that have wiped out entire tribes in the past.

“Once their territory is encroached by loggers or prospectors, the isolated groups are finished,” Meirelles said. “They could disappear from the face of the Earth, and we wouldn’t even know it.” (See the photos of an uncontacted tribe that stirred an uproar.)

Although they seek to avoid direct contact with outsiders, the Indians at the headwaters of the Envira and Humaitá rivers have long made use of steel tools. “Dating back to 1910, there have been reports that they raided settlements and made off with machetes and axes,” Meirelles said. “They’ve been using them for a long time. They’re practically part of their culture.” The tools have allowed them to clear large enough swaths of forest to expand food production. Since the group has never sustained peaceful contact with the outside world, the name of the tribe is unknown. Brazilian officials simply refer to them as the “isolated Indians of the upper Humaitá.”

A former staff photographer for major Brazilian media, including Veja and O Globo, Stuckert said his four children are his most important audience. “They’re very curious, always asking questions,” he said. “They are very interested in how these Indians live, these people who were the very first human inhabitants of our country. They want to know every detail.”

Stuckert hopes his forthcoming book, Índios Brasileiros, will awaken the curiosity and conscience of successive generations, so that they might also experience the spine-tingling sensation he felt as he beheld the village from his perch in the helicopter.