Most readers think that superheroes began with Superman's appearance in Action Comics No. 1, but that Kryptonian rocket didn't just drop out of the sky. By the time Superman's creators were born, the superhero's most defining elements--secret identities, aliases, disguises, signature symbols, traumatic origin stories, extraordinary powers, self-sacrificing altruism--were already well-rehearsed standards. Superheroes have a sprawling, action-packed history that predates the Man of Steel by decades and even centuries. On the Origin of Superheroes is a quirky, personal tour of the...