On one hand, you know exactly what you're getting by the stagey make-up and hammy performances used to depict prehistoric man. They were hallmarks of star-driven movies from the golden era right through to the late 60s, the focal point of which is Raquel Welch's perfectly styled and lustrous hair (somehow maintained a million years before shampoo).

On the other hand, it's surprisingly smart about the way early humanity would have behaved, particularly in the early scenes setting up life in prehistory. It's quite frank about the alpha male-led tribal structure to the way interlopers risked expulsion from the group, as happens to hero Tumak (Richardson) when he becomes embroiled in a leadership challenge.

After wandering across the desert battling starvation and a giant iguana and hiding from the fearsome apes that live in an idyllic cave, he finds his way to the more peaceful (and distinctly Aryan) ocean people, stumbling across their efforts to fend off a giant tortoise.

Tumak shares knowledge and finds something like a new home with the sea people, particularly the winsome Loana (Welch). But he can't keep his savagery in check, and before long the sea people cast him out as well, Loana so taken by him she goes with him. He returns to the cave tribe and the fight is on claim the best prize in camp.

But the sea people follow them back, and when inter-tribal war is about to break out the local volcano stops everyone in their tracks. It rains chaos and carnage down from above and decimates the population, the bedraggled remnants with no option but to stagger out of the smoking landscape and try to keep surviving. In a perhaps unintentionally smart piece of storytelling, it's a simple and powerful device to portray the life of lurching from one disaster to another, never knowing which one is going to punch your ticket.

I didn't know before watching that it the immortal Ray Harryhausen did the creature scenes. The plot itself gets a little bit episodic as the tribespeople battle one rubber-suited dinosaur, stop-motion animated pterodactyl or superimposed film of a real animal after another. It probably wasn't even that scary or realistic-looking for audiences in the late 60s, but it's more insightful and thought provoking that you'll ever expect to see from such an essentially schlocky movie.

And next time someone growls about how Hollywood's an endless string of sequels and remakes nowadays, remind them that this was a remake of a Lon Chaney movie from 1940.