Documentary films, except when being screened for documentary filmmakers, are usually dependent upon their subject matter to interest an audience. But the subject of cannibalism brings out the more prurient interest in any audience -- like the innocuous college kids who ask Tobias Schneebaum questions that one would expect to be thought rather than voiced: "What do people taste like?" and "Which part did you eat?" Schneebaum dodges the questions of the class he is lecturing with a practiced ease. This is how "Keep the River on Your Right" begins.

From the Metropolitan Museum of Art in New York the film follows Schneebaum to New Guinea, where he once lived among the Asmat natives, and now supplements his retirement by acting as a guide on a cruise line. Much of this part of the film is interesting, including the irony that Schneebaum hates tourists and tourism, yet collaborates with the industry for the money. A trip up river to a village where he once lived and his reunion with old friends and a lover only confirms Schneebaum's fear that the world he once knew has been devoured by modernization.

Yet the first half of the film, despite these highlights, remains defused. It is part travel log, part polemic on the nature of homosexuality in primitive cultures, and part anthropology. But the sum is less than the whole. The second half of the film, however, jumps into sharp focus with story of Scheenbaum's first expedition to the primitive world.

Mr. Schneebaum was an up and coming New York painter in 1955. That was the year he got a Fulbright Fellowship to go to Peru. After visiting the ancient Inca ruins, he went to stay with a missionary in the jungle. Upon hearing that some of local people had left the mission and killed those sent to ask them to come back, he ventured out into the bush to find them with nothing more than the clothes on his back and a little food. When he found them, the tribe adopted him and he spent several months living with them. One of the hunting trips he went on with them turned out to be an attack on another tribe. Some of the villagers were killed, and in the celebration afterwards he was offered, and ate, a small piece of human flesh.

The above synopsis doesn't get to the heart of the film, however. The real story is about a 78-year old man lead, sometimes willingly, sometimes almost forced, to confront the seminal event in his life almost half-a-century past. After the incident (as he almost always refers to it) he lost the drive to paint and become a minor celebrity when he published his story and became an anthropologist. As Scheenbaum and the camera crew journey up the river to find his past, he has to confront his own fears. Not just that the tribe he was once part of now watches satellite TV (which it does), but his own, very human, nature. As he says as he leaves with the film crew, "I didn't want to come, but I'm glad I did now."

Though the first half of the documentary is rather ordinary, the second half of David and Lauren Gwen Shapiro's project becomes not just good film making, but great storytelling. They even get Scheenbaum to answer the question everyone seems to want to know - humans taste a little like pork.