Haddon has classified the races on the basis of hair in his book ........................

A.C. Haddon proposed a hair-based classification of human populations in his work "The Races of Man and Their Distribution" (commonly cited as "Races of Man"), grouping populations by hair texture into ulotrichous (woolly), cymotrichous (wavy), and leiotrichous (straight) types. Such hair-based racial taxonomies are historical anthropological schemes rather than valid modern biological divisions of humanity.