the higher its shrinkage. The shape of the hair follicle determines the hair's curliness. An individual hair's shape is never completely circular. The cross-section of a hair is an ellipse, which can tend towards a circle or be distinctly flattened. East Asiatic heads of straight hair are formed from almost-round hair follicles producing straight hair, and European hair follicle forms oval shapes which produce wavy hair. Afro-textured hair has a flattened cross-section and is finer, and its ringlets can form tight circles with diameters of only a few millimeters. In humans worldwide, East Asiatic-textured hair is the most common, whereas kinky hair is the least common. This is because the former hair texture is typical of the large populations inhabiting the Far East as well as the indigenous peoples of the Americas. Evolution Robbins (2012) suggests that afro-textured hair may have initially evolved because of an adaptive need amongst humans' early hominid ancestors for protection against the intense UV radiation of the sun in Africa. The author argues that afro-textured hair was the original hair texture of all modern humans prior to the "Out-of-Africa" migration that populated the rest of the globe. According to Robbins (2012), afro-textured hair may have been adaptive for the earliest modern humans in Africa because the relatively sparse density of such hair, combined with its elastic helix shape, results in an airy effect. The resulting increased circulation of cool air onto the scalp may have thus served to facilitate the body-temperature-regulation system of hominids while they lived on the open savannah. Afro-textured hair requires more moisture than straight hair and tends to shrink when dry. Instead of sticking to the neck and scalp when damp (as do straighter textures), unless completely drenched it tends to retain its basic springiness. The trait may have been retained and/or preferred among many anatomically modern populations in equatorial areas, such as Micronesians, Melanesians, and the Negrito, because of its contribution to enhanced comfort levels under tropical climate conditions. In rare cases, kinky hair may also be found in populations living under temperate climate conditions, such as indigenous Tasmanians. History Historically, many cultures in continental Africa developed hairstyles that defined status, or identity, in regards to age, ethnicity, wealth, social rank, marital status, religion, fertility, adulthood, and death. Hair was carefully groomed, as the social implications of hair grooming were a significant part of community life. Dense, thick, clean, and