Chapter 6 203 component of the hair functions to shield the load-bearing cortex from environmental stresses. However, this level of protection is not equal across all ethnic groups. Hadjur et al. showed that the distance in space between cuticle layers increased in order of Asian, Caucasian and African hair (Figure 3). They also indicated that the number of cuticle layers were the same (~ 6-8) for the Asian and Caucasian hairs, but that African hair had as few as 1-2 layers on the sides of its minor axis of the ellipse. The number of cuticle layers on the major axis approached that of the other hair types.30 In more recent work, Japanese and Caucasian hairs were compared using scanning electron microscopy (SEM) and showed that the Japanese hair had thicker cuticle scales and more of them.33 One may speculate that the tighter the layers and the greater they are in number, the greater protection they provide. Geometry: Color aside, the most noticeable difference in hair is its geometrical appearance. Asian hair is typically straight, circular in cross-section and has a thick diameter that’s fairly uniform along its length. Natural African hair is on the opposite end of the Figure 3 Field emission scanning electron micrograph of cuticle spacing in African, Caucasian and Asian hair.