Chapter 6 219 role of ethnicity, which can be influenced by environment, diet and grooming practices. Conclusion The properties of hair have been studied for decades. Early studies sought correlation of physical and geometric properties with race and, more recently, ethnicity. With exception of mechanical properties like break stress and geometrical properties like cross- sectional area and ellipticity, early results were inconsistent. The issue does not appear to be the use of race or ethnicity to group like samples, but the test methods utilized. The use of advanced techniques with higher resolution which allow the non-destructive analysis of hair have led to improved agreement in data reported for hair properties and structures. There is strong evidence that curly hair is programmed from the bulb and that some genes are associated with several specific hair attributes. This would certainly point to the hereditability of certain hair characteristics. However, other results like the confirmation of a deviation in the distribution of cortical cells are linked to curl and not to race or ethnicity. In order to move to a more universal classification system and in recognition of the mixing of cultures, a worldwide curl classification was developed and used to evaluate many of the same properties studied earlier. Indeed, this more objective classification revealed strong correlations between curl and break stress, cross-sectional area, and ellipticity, all previously studied as a function of race. On the other hand, all three parameters are also strongly influenced by ethnicity. In fact, it is difficult to use one without the other, because at the extremes, curl classes I and VIII, ethnic diversity of available hair samples is limited. The role of ethnicity as a strong determinant in diet, environment and grooming practices is evident in the analysis of the self-perceived hair problems survey. So, as we continue to evolve as a human race with more cultural mixing, these differences are expected to dwindle. Eventually, curl and ethnicity may converge to provide a more diverse curl pattern for each