Skin painted bright red, heads partially shaved, arrows drawn back in the longbows and aimed square at the aircraft buzzing overhead. The gesture is unmistakable: Stay Away. Behind the two men stands another figure, possibly a woman, her stance also seemingly defiant. Her skin painted dark, nearly black. The apparent aggression shown by these people is quite understandable. For they are members of one of Earth's last uncontacted tribes, who live in the Envira region in the thick rainforest along the Brazilian-Peruvian frontier. Thought never to have had any contact with the outside world, everything about these people is, and...