The hushed, eerie Chauvet caves in southern France contain the oldest known artwork on our planet, extraordinarily well-preserved drawings made 32,000 years ago.

During this era, while lions and rhinos roamed Europe, Neanderthals and their advanced Cro-Magnon cousins were competing branches on our ancestral tree. The appearance of cave art marks the origin of symbolic thinking, making possible written language, science, symphonies and napalm. It was the birth of the modern human soul, and cinematic explorer Werner Herzog's fantastic "Cave of Forgotten Dreams" is the delivery-room video.

Herzog was granted exclusive access to the cavern system, whose delicate surfaces could be ruined by the excess exhalations of visitors. Employing a three-member crew with handheld cameras and lighting, his visuals evoke the shifting lights and shadows of a Paleolithic artist's torch. The images are of horses and bears and panthers, their movements so sharply observed and vividly rendered that Herzog declares them "pre-cinematic." Human forms are absent except for grotesque images of interspecies mating. Elsewhere are red-orange palm prints like polka-dot clusters -- the beginnings of abstract art, possibly. The cave wasn't a dwelling but most likely a ceremonial space. What were the ceremonies? Herzog doesn't speculate, content to leave imponderable mysteries alone.

Paleontologists and art experts provide some background, but Herzog's quirky narration carries the show. His dry, nasal drone and skeptical intelligence offer a stark frame for the wondrous artworks; how diminished the experience would be if our tour guide gushed.

He is lightly mocking of Chauvet's resident scientists, some of whom obligingly dress up in animal pelts and throw wobbly spears for his camera. Convinced that reason can carry us only so far, he's pessimistic about our ability to comprehend the meaning of this underground gallery.

In a characteristically bizarre passage, Herzog shifts the focus to a nuclear reactor near Chauvet, where albino crocodiles breed in the warm runoff. Confronted by our ancestors' earliest messages to us, he seems to say, we are as uncomprehending as mutant amphibians. The film is not without its moments of tedium, but in inspired moments like this, all is forgiven.