| Hair texture varies greatly in humans. Because of its strong correlation with regional ancestry, hair texture has been used as a secondary or even primary classifier of race by several early anthropologists. Hair texture in humans ranges from coarse straight to peppercorn hair. The great variation of this trait within one species is quite unique in the animal kingdom and paralleled only by sheep. The most tightly curled hair may form a circle every 1.5 millimetres. On average hair is slightly curlier in males and after puberty. The reason for the great variation of hair texture is not exactly known yet, and studies are missing. It has been suggested that kinky hair offers a protection of the head against solar radiation, because it occurs more frequently in tropical populations. Against this is the fact that many kinky-haired individuals living in tropical regions customarily shave their heads. Additionally, the peppercorn hair of some African populations has carried curvature to the point where it serves no insulating or protective functions. There exist various hair classification systems, among them the Andre Walker hair types that ignores the category of peppercorn hair, or the FIA hair classification. An early very detailed hair classification is that of Martin (1928), who divided smooth hair (coarse straight, smooth, smooth wavy), curly hair (loose wavy, tight wavy, curly), frizzy-hair (crimped, loose frizzy, tight frizzy), peppercorn (fil fil), spiral). This site uses the simplified categories of coarse straight, (fine) straight, wavy, curly, tight-curly, kinky, and peppercorn hair. The map shows regions where a specific hair texture is common in native populations. On an individual level, different hair textures may regularly appear in the black areas as well. |