If youÃ¢â‚¬â„¢re thinking itÃ¢â‚¬â„¢s impossible that such an isolated group could exist in the Philippines as late as the 1970s, youÃ¢â‚¬â„¢re right. It turns out that their “discoverer,” PANAMIN (Private Association National Minorities) secretary Manuel Elizalde Jr., paid local farmers to live in the caves, take off their clothes, and appear Stone Age. In return he gave them money and security from counterinsurgency and tribal fighting.
A bonus link, Neatorama also pointed me to this account of dragging a World War II tank out of a lake. With muddy, muddy photos.