Chauvet cave features 3-meter-high paintings of horses, fighting rhinos, and cows. Narrow tunnel leads to spectacular prehistoric artwork. Anthropologists ignored semicircles, lines, and zigzags as doodles. Latest research proves marks are highly symbolic written code. Code familiar to all prehistoric tribes around France and beyond. Marks provide snapshot of humanity's first symbolism and writing steps. Challenge accepted view of creative explosion 30,000-40,000 years ago. Jean Clottes saw paintings firsthand and describes horse heads leaping from walls.