It's true that a lot of cultures have used bones for many things, (both animal and human bones), but usually they use bone from people who have died already or animals that were hunted for food or skins, etc. However, I think on Manitu, they actually made it a practice to kill people *specifically* to make musical instruments out of them. You could say it was a kind of big "marketplace" (even if they didn't use money there) and you got the feeling they killed people just for their body parts. Also, it is implied that this is what they do with practically all the visitors who "disappeared" before. During the episode, it is mentioned that people went to Manitu and were never seen or heard from again. By the end of the episode, I think the listener is supposed to figure out that this goes way beyond a tribal culture's use of bones to make things. On the surface, they *seem* like such a peaceful culture, but underneath they are really after human bones for the quality of "sound" they make in musical instruments. They will stop at nothing to get those parts and since everyone on Manitu loves music, there is always a great demand for more of these musical flutes. I think that's what is supposed to make it scary. I really wasn't all that scared, but I thought the episode was done very well, so it remains interesting.