As an example of their willing gullibility, from that site:
Disclosure - In 1986, nearly 15 years after the Tasaday were first discovered, everything changed. General Marcos's tyrannous regime was ousted and a new, freer, democratic government took its place.
A Swiss writer and Anthropologist named Oswald Iten took advantange of the opportunity to study the Tasaday without the former government's restrictions. He brought Joey Lozano, a journalist from South Cotabato, with him on his expedition. Strangely, when they reached the caves, they found them deserted. A search of the surrounding area led to the discovery of the same "Stone Age" people a short distance away living in modest huts, wearing T-shirts and blue jeans.
Iten and Lozano realized that the whole thing was a glorious hoax. Further research showed that the Tasaday actually came from two other tribes, tribes that had been part of the modern world for years. They publicized their findings through an ABC television documentary entitled The Tribe that Never Was. Millions of viewers were confronted with the images of Filipinos in T-shirts and Levi's laughing at the pictures of themselves from National Geographic. One anthropologist called the Tasaday, "rain forest clock punchers" who were "cave people" by day and went home to their families at night.
In retrospect, the fraud seemed obvious. Why, some wondered, were the caves so clean? Even a Stone Age tribe would have had garbage, such as crab shells or scraps of food. And how did such a small tribe avoid inbreeding? Also, the Tasaday were a mere three hours walk from an modern village. It seemed odd that they would not have encountered this village while searching for food. And if that was not enough evidence of a hoax, anthropologist, Thomas Headland conducted an investigation on the Tasaday and produced "eight little known facts about the Tasaday." These were:
1. The Tasaday were found wearing commercially manufactured cloth. They were asked to remove their clothes and wear their "traditional" garb.
2. The Tasaday must have traded with other tribes. They had brass, metal tipped arrows, bows made of cultivated bamboo, glass beads, iron knives, and tin cans, just to name a few of the foreign items that Headland mentions.
3. Nearby tribes ate meat from animals killed by the Tasaday, and gave them cultivated food in return.
4. The South Cotabato rain forest lacks the amount of starch foods necessary to sustain the Tasaday. Headland writes, "It has been generally assumed until recently that tropical rain forests are food-rich biomes for human foragers, and that prehistoric hunter-gatherers once lived completely independent of cultivated foods in such environments. An alternative hypothesis that such forests are actually food-poor for humans is proposed here. Specifically, that wild starch foods such as yams were so scarce and so hard to extract that human foragers could not have lived in such biomes without recourse to cultivated foods...."
5. The Tasaday were never directly observed subsisting on gathered food. Scientists simply assumed they did.
6. The Tasaday bamboo tools were cultivated bamboo. Their bamboo was the sun-loving type which cannot grow in the rain forest.
7. The Tasaday stone tools were fake. They were made at the request of the officials in charge.
8. In the Tasaday language, 85% of the words were identical to the Cotabato Manobo speech, which is spoken by most of the tribes in the area.