I would suggest you read the book. The acting wasn't horrible. Except for the Neanderthals. All their grunting and screaming got old. In the very beginning there's a naked girl and I thought, this can't be bad. I was wrong. It's as if they went looking for the ugliest naked girl they could find. There's also some kind of weird pederast sex going on with an old guy that just lays in the dirt making noises. Also, weirdly, Neanderthals shave their faces, legs and vaginas. Then there's the strange sadist caveman rape scene which includes the caveman biting off the girl's labia. The problem with the movie is that it doesn't really explain any of this any better than I did. The he only redeeming quality of this movie was titties. And even they weren't that great. If none of this deters you from seeing this film, they also kill a couple babies in it. But if you're into that kind of thing...