The presence of hair is one of the main characteristics seen in most mammals. The reason as to why we have hair on our bodies and why it grows in such distinct, varying ways is not completely clear, however, it is certain that it does provide several functions that we benefit from in our everyday lives, such as:
Protection against environmental factors
Our hair, even the miniscule hairs on our arms, provides our bodies with minimal protection against potentially harmful environmental elements such as sun damage from UV rays and chapped skin from wind damage. It also acts as a filter for dust and dirt particles.
Hair helps to insulate our bodies in two ways:
(1) by acting as a barrier between cold air and skin, and
(2) and by trapping warm air closer to our bodies and thus keeping us warm.
Extending sensory capability
Similar to some animals, our hair has the ability to extend our sensory perception, though this ability is not as finely tuned as it is in animals, as we do not have the same amount of sensory nerve fibers in our hair roots as animals do. This extension of our sensory capability is apparent when the tiny hairs on our arms are displaced, thus allowing us to become aware of the disturbance.
Buffer against friction and sweat
Hair acts as a buffer, particularly in areas that are prone to rubbing together. Hair also absorbs sweat and redirects it away from these areas, so as to avoid skin irritation from chaffing or blistering. By absorbing and redirecting sweat, hair can help the body cool down or dry off faster in the areas that need it.