Story, first published: Analog Science Fiction / Science Fact, April 1980
A paleontologist working in the Pyrenees uncovers incontrovertible evidence that Luis, his assistant at camp, is a Cro-Magnon who has survived, impossible as it may seem, for 22,000 years. The heart of the story is the price that Luis has paid for his immortality, his solitude. Luis is the loneliest man in the world.
Ewald, Robert J.: When the Fires Burn High and the Wind is from the North, p.126