Hair Ethnicity 194 a deeper understanding emerges that often further refines the classification systems. The grouping of hair to explain physical and morphological variations is no different. Early attempts to describe hair were mainly based on race, namely Negroid, Caucasoid, and Mongoloid.1-3 In more recent times, hair classifications became a combination of race and ethnicity, where most research has been focused on Black, Caucasian and Asian.4,5 As a result, the term ethnic hair is used to describe many different hair types. Some populations consider ethnic hair to be afro hair, to some it is non-Caucasian hair and to others it is simply curly, kinky hair. Race and ethnicity are often used interchangeably however, according to Webster’s Dictionary, race is a category of humankind that shares certain distinctive physical traits, and ethnicity is defined as relating to large groups of people classed according to common racial, national, tribal, religious, linguistic, or cultural origin or background. These definitions are important as you consider the need to categorize hair in order to objectively study its physical, geometric and chemical properties. Race, as we will see, was once an adequate classification describing the appearance of the hair and was thus correlated with groupings of geometric properties such as degree of curl. As the mixing of the races continues, the variation in these properties becomes greater within racial groups. Ethnicity, however, is still important as it may be the determinant factor in diet, UV exposure and grooming practices, and therefore, influence the state of the hair at the time of analysis. Evolution of Curl The potential importance of the degree of curl in hair forces one to consider why the difference exists. Anthropologists and other scientists have attempted to explain the variation in hair curliness using the predominate theory for the evolution of the relatively hairless man.6,7 The theory is based on thermoregulation, sweating and the body’s ability to cool itself.6 The loss of hair allowed for more efficient cooling. However, in the case of head hair, it is believed that it provided protection against UV radiation. Millions of years