Snakes cannot blink, and that unblinking stare left a mark on human language: the English word dragon traces back to a Greek verb meaning to see clearly. This deep dive explores why societies separated by oceans all imagined a giant, scaly, flying monster. We weigh anthropologist David E. Jones's primate theory, which blends our ancestral fear of snakes, big cats, and birds of prey into one composite predator, against Adrienne Mayor's fossil theory, in which giant giraffe bones in the Mediterranean, prehistoric bones in India's Siwalik Hills, and Chinese dinosaur fossils gave ancient people physical proof that monsters were real.

Then we follow the dragon's split personality. In Egypt, Apep attacks the sun god Ra and explains eclipses; the Leviathan breathes fire in the Book of Job; Babylon's mushussu fuses snake, lion, and bird. Christian  ...