Carter first visited here 12 years ago. He decided to stay a month. "I wanted to figure out how to help them put value in their culture," he says.

The tribe, best known for its beautiful jewelry, didn't know how to count, so Carter helped them itemize their arts and crafts and came up with a price list. Then he started flying in small groups of high-dollar tourists to buy the jewelry. The program has been so successful—the tourist fees ($450 per person), plus the income the Indians generate by selling their crafts, covers close to 30 percent of the tribe's total annual operating costs—that now nearby villages want a similar system.

"This is one of the best-preserved tribes in the Amazon," says Carter. "They live in the middle of all these ranchers and farmers and haven't been beaten into submission. Ask any villager and they'll tell you that they don't want to leave."

Just when I start getting used to the idea that this may be a culture that can live without Facebook, the chief pulls up in a massive flatbed truck. Kotok is about 50, has a Beatles-style bowl cut, and is wearing flip-flops, khaki shorts, and a T-shirt. He's smoking a cigarette and looks like a surfer.

About five minutes after Kotok arrives, he strips naked, but keeps the cigarette. Four members of a Brazilian documentary film crew came with the chief in the truck. The little kids pull up an assortment of chairs near the tailgate to watch them unload their gear. The crew is here for two weeks to tape video for a piece that will ultimately become an art installation in a museum in Brasília.

When the director, Álvaro Andrade Garcia, finds out that the gringo in the Wranglers is John Carter, a man he's been tracking for months because he's a rancher sympathetic to the plight of the Indians and a passionate conservationist, he sits Carter down for an interview.

In Portuguese with the camera rolling, Carter spreads his sound bite to the world: "Ranchers aren't devils!" he says. "The real responsibility lies on the backs of the government, a task they fail to shoulder. But along with white landowners, Indians have an important role to play in Amazonian conservation. Twenty-five percent of it is in their control. But they, like whites, need financial incentives!"

Tacumã, the village shaman, who's sitting under a tree next to the film crew, slowly nods in agreement.