To most historians, the colonial accounts came to seem exaggerated, though exactly why was not often explained. (“Sixteenth-century Europeans,” Cook and Borah dryly remarked, “did indeed know how to count.”) Especially in North America, historians’ guesses at native numbers kept slipping down. By the 1920s they had dwindled to forty or fifty million in the entire hemisphere. Twenty years after that, the estimates had declined by another factor of five.
