When we had paddled our way back to the stretch of the Vézère below Castel-Merle, we pulled out our canoe at the boat landing in Sergeac and walked a few minutes to a narrow vallon, a small side canyon. Students were working under a shed roof, excavating a thin layer of a floor 33,000 years old in a rock shelter called Abri Castanet.

Abri means shelter in French, and this vallon, about 100 yards across and 300 yards long, has at the bases of its cliffs a dozen such shelters, containing some of the oldest known carvings and paintings, as well as cruder artifacts going much further back. Marcel Castanet, the first excavator at this spot, is the source of the name for Abri Castanet. His descendants still own the land  and Castel-Merle  and his son, René, runs a small museum of prehistory in Sergeac. René’s granddaughter, Isabelle Castanet-Daumas, an archaeologist, owns the vallon and offers tours of its rock shelters.

In a Quonset hut beside Abri Castanet, Dr. Randall White, a professor of anthropology at New York University, was excavating refuse from a 33,000-year-old bead workshop. He picked through bead-making residue with a pair of tweezers, separating tiny shards of hematite, used for polishing, from equally minuscule scraps of the charred reindeer antler and bone. The beads themselves were made of mammoth ivory and soapstone, materials prized apparently for their smoothness. Behind him, students uncovered a section of the ancient floor with brushes. “We’re picking through the garbage of everyday life 33,000 years ago,” he said, holding up the tiny ulna of a prehistoric bird or rodent.

The nomadic hunters called the Cro-Magnon, who were, like us, Homo sapiens, existed here from about 40,000 to 10,000 years ago, and wintered in the vallon sporadically over that time. The canyon sheltered them from cold winds, and the natural rock overhangs allowed them to hold heat inside by hanging hides over the openings of their shelters. It is thought that different groups met in those cold months and shared materials, techniques and genes before separating to go to their summer hunting grounds in the spring.

Their own ancestors had come to Dordogne from Africa, taking thousands of years to get there only to find another human species already in residence  the Neanderthal.

Professor White believes that the shock of that contact was an impetus for the Cro-Magnon use of body ornamentation. “Ornamentation helped them organize into large groups and identify each other across wide distances,” he said. Their distinctive styles of beadwork and clothing made them identifiable as Cro-Magnon and differentiated them from the Neanderthals. In this view, ornamentation was not only the beginning of metaphor  the taking of an image or material out of one context and placing it in another  but also of the concept of social status. Abri Castanet is one of the richest sources of concrete evidence for ornamentation, though earlier so-called “find spots” exist in France and South Africa.

From the vallon we followed a centuries-old trail under the overhanging cliffs and through oak forests along the river for almost a mile, to the next village, St.-Léon-sur-Vézère, and back to Castel-Merle. Here the wild surroundings made it possible to imagine the landscape as a preagricultural refuge for early humans, if not as the dry grassland that once existed here.