Chapter 14 467 (r2 = 0.18). Therefore, for Japanese women there is an increase in hair fiber curvature with increasing age which has a negative effect on hair luster, especially at advanced age. In a different publication by these same authors,26 frizziness was explained as a lack of synchronization in the curvature of neighboring hair fibers in an assembly of hair. Therefore, this increase in hair fiber curvature with age could create the appearance of frizziness with increasing age, which should be explored. We would expect a similar effect of age on hair fiber curvature among Caucasian women and men however, this hypothesis awaits empirical determination. Also, the effect of age on hair fiber curvature among those of African descent requires additional study. In addition, the effects of a loss in hair luster and an increase in frizziness with increasing age remain to be examined among Caucasian and African groups. We know that hair curvature has an exceedingly important effect on almost every important cosmetic hair property therefore, we believe that the effects of hair curvature versus age and all cosmetic hair assembly properties is a major gap for future study. Ellipticity and age: We have located five studies of hair fiber ellipticity versus age.13, 18-20, 26 Three of these papers are relatively large studies. In the earliest paper, Trotter20 took hair fibers from the vertex of 340 Caucasian (American) males and females at different ages, measured the maximum and minimum diameters, and calculated both cross-sectional sizes and ellipticity. Trotter initially separated the groups into males versus females and measured ellipticity for age groups set at every 10 years from age 0 to 79. One concern with the data of that study was the small and varied sample sizes (only 10 hairs per subject, and the number of subjects per age group varied from as low as 1 to as high as 45). Trotter next examined hair from the vertex of 300 French Canadians measuring maximum and minimum diameters and reported hair shaft indices (D min /D max x 100) and cross-sectional areas by age group separating the data into hair of males and females.19 Table 6 summarizes the data from both Trotter studies.