* Protection: Hair provides a physical barrier that protects the scalp and skin from harmful elements like sunlight (UV radiation), heat, cold, and minor injuries. Eyelashes and eyebrows protect the eyes from debris and sweat.
* Thermoregulation: Hair can help regulate body temperature by trapping a layer of air near the skin, providing insulation in cold weather. When it's hot, hair can help to dissipate heat through evaporation.
* Sensory perception: Hair follicles are connected to nerve endings, making hair sensitive to touch, air movement, and temperature changes.
* Social and sexual signaling: Hair can play a role in social signaling, identification, and attractiveness in many cultures. Hairstyles, color, and grooming can convey information about a person's identity, status, and intentions.