Another movie to identify--cavemen "evolve" into rich people then devolve

Years ago, late at night, I saw a film on TV in Japan part of which was in German, and part of which was in English. The film started out seeming like a documentary about caveman-like folks in the jungle. Then the cavemen found a mansion, and started playing various mansion-folk roles. Their grunting evolved into talking, and eventually they appeared to be well-mannered rich people at a civilized rich-people party. This part was all in English IIRC, and the German speaking “documentarian narrator” did not speak for quite a while. The people in the mansion got tangled up in some kind of soap-opera-esque plot. Then finally, they started devolving as emotions got more intense. At the end, they were back to being cavemen, running around the property and fighting each other. I believe the German Documentarian Narrator returned at thi point.

What was this movie?

-FrL-

Die Pleistocene Hillbillies?

Savages.

I saw part of this on late night TV in the 80’s. I thought it was just a drug-induced fantasy.

Wow, after that description I was not expecting to find ‘Director: James Ivory’ on imdb.

And apparently, I now discover, Sam Waterston is in it!

I may have to buy this thing.

-FrL-