I saw part of this movie on cable in the 80s. It was in color and English language, but not American. Possibly from New Zealand, South Africa, or Australia.

A boy around 12(?) years of age is very curious about science and anthropology. It’s all he talks about. He has a book or a magazine (it might have been National Geographic) with lots of photos in it. His parents are concerned because there is a photo of a bare-breasted native woman in it. They think he’s so fascinated with it because of the nudity. So they ask him to compare the woman in that photo to another one and tell them what is so interesting about her. He thinks for a moment, then he says that she’s “better fed,” due to the rainy season.