The Effects of Aging on Hair–More Than Just Amount 458 No comparable data on graying of hair versus age based on large numbers of Asians or Africans could be found in the literature. Therefore, assuming that the conclusions of Tobin and Paus are correct, that graying begins for Asians and Africans about 5 years and 10 years, respectively, later than for Caucasians and that once graying begins the rate of graying is the same for all three of these geo-racial groups, then one can approximate the incidence of graying versus age for Asians and Africans by examining the data of Table 2 and moving each graph point or data point back 5 years for Asians and 10 years for Africans. Until sufficient data can be obtained for large numbers of people of Asian and African descent, these approximations should be useful. Conflicting literature on interdependence of graying and hair curvature, diameter: There is conflicting literature as to whether gray hairs are coarser or finer than highly pigmented hairs. For example, Hollfelder et al.10 provided evidence from five Caucasians that gray hairs on the same person are coarser and wavier than highly pigmented hairs. This observation by Hollfelder et al. is consistent with observations by Yin et al.11 that fine Caucasian hair is straighter than coarse Caucasian hair. Similarly, Van Neste examined 60 hairs from each of three different scalp sites on 24 women, and a global comparison of all hairs (more than 3,300) showed that the average diameter of non-pigmented hairs exceed that of pigmented hairs by approximately 10 µm.63 Furthermore, both Van Neste and Hollfelder reported a more prominent medulla in non-pigmented compared to pigmented hairs.10,63 If this is the case, then the more prominent medulla would likely provide the appearance of whiter or grayer hair by scattering light and changing the refractive index at the hair-to-air interfaces of the medullary pores. However, Gao and Bedell,12 studying gray hair and dark hairs from four persons plus one sample of pooled gray hair, measured cross-sectional parameters with a laser-scanning micrometer and found no significant differences in the maximum center diameter, center ellipticity, or cross-sectional areas however,