The cave of Lascaux -- the "Sistine Ceiling of the Cave Man" -- is a spectacular window into the shadowy, powerful animal world of the Old Stone Age, some 17,000 years ago. The chance discovery of two boys in France in 1940, the cave was soon overwhelmed by tourists and in the early 1960s showed inescapable evidence that its radiant frescoes of bison, aurochs, horses, and deer were dimming with molds and fungi generated by bright lights and the warmth...