Final answer:
African hair differs from European and Asian hair due to genetic factors determining the shape of the follicle and hair fiber, and the type and distribution of melanin. Curvature and cross-sectional shape of hair contribute to the distinct texture, while hair plays key physiological roles such as UV protection and thermoregulation.
Step-by-step explanation:
The difference in hair texture among African, European, and Asian individuals can primarily be attributed to genetic factors that determine the shape of the hair follicle and the hair fiber, as well as the distribution and type of melanin present in the hair. African hair is typically characterized by a flattened elliptical cross-section, which contributes to its tight curl pattern, while European and Asian hair tend to have a more circular cross-section leading to straighter hair. The keratinocytes in hair produce keratin, a protein that is responsible for the hair's structure and strength.
Hair texture is also indicative of various physiological roles such as protection from UV radiation, sensory input, and thermoregulation. Cultural factors additionally play a role, with African and African diasporic hairstyles holding significant social implications, denoting factors such as social status and tribal belonging. Over time, genetic variation and adaptation to different environmental conditions have let to the diverse hair textures observed in human populations around the world.