Your scalp has 100,000 hairs.
Redheads have 90,000; black-haired people, 110,000.
Head hair grows about 5 inches a year.
Humans are as hairy per square inch as chimps but don’t show it, since most hairs are too fine to be seen.
Individual hairs live anywhere from 2 to 7 years (eyebrow hair 3 to 5 months).
An adult human head weighs more or less 8 pounds, even without hair.
Hair analysis is like a fossil record. It can reveal drug use, nutritional habits, and many aspects of your health. It cannot reveal gender.