Comparative thickness of human hair

This image shows the difference in thickness of human hair between different ethnic groups. The strand of hair on the left is that of a Caucasian blonde female. The hair on the right is from an Asian male. Hair is normally comprised of three layers, the inner medulla, the cortex and the cuticle. The cuticle is the outermost layer and is comprised of numerous overlapping cells or scales. The cortex makes up the majority of the hair thickness. Interestingly, the inner medulla is not present in blond hair.