Curly Hair: Follicle's Secret to Cooling Heads

The formation of curly or straight hair is determined by the shape of the hair follicle beneath the skin. Straight hair grows from vertical follicles, while curly hair originates from bent, asymmetrical follicles where cells divide and mature differently on opposite sides. This structural difference creates a kinked strand. Recent evidence suggests that cells on one side of the follicle divide and mature in different ways from the opposite side.

While hair composition plays a role in texture, the follicle's shape is the primary determinant of curl. This genetic trait means hair types often run in families. The evolution of hair follicles is thought to be linked to thermoregulation. Studies in 2023 showed that hair, particularly curly hair, helps the head absorb less heat from solar radiation, making it more effective at cooling compared to baldness or straight hair.