Many animals, and even plants, have fur and tiny hairs that serve different purposes. Animals need fur to keep warm, for camouflage, and, in some cases, to warn or signal other animals with the special markings on their coats. Evolution has proved that these reasons for having hair are not as important to human survival. Humans have developed to have very little hair to help keep warm and communicate with one another compared to other organisms that use their fur for these reasons.

Warmth

Polar bears use their fur for warmth, camouflage while hunting and for protection by hiding cubs in the snow.

While humans have developed clothing and other means of keeping warm, the hairs found on the head and other parts of the body serve as primary sources of heat and insulation. Hats and coats are still required while doing outdoor activities to prevent frost bite and hypothermia, but the hair on the human body does help to keep the internal temperature regulated. When the body is too cold, the erector pili muscles found attached to hair follicles stand up, causing the hair in these follicles to do the same. These hairs thus form a heat-trapping layer above theepidermis. This is called piloerection, which is a Latin word where 'Pilo' means hair and 'erect' means to stiffen. This process is more commonly known as having goosebumps. The opposite happens when the body is too warm. The erector muscles make the hair lay flat on the skin which allows heat to leave.

Protection

Human hair may not compete with the painful spines of the porcupine, but much of the hair on the human body is suited to protect it. This natural armor cannot directly protect humans from potential predators, but it does help to keep the sense organs, like the eyes, working properly.

Eyebrows and eyelashes

Eyelashes and eyebrows help to protect the eyes from dust, dirt, and sweat

The eyebrows are situated above the eyelids on the forehead. While they have little significance to the survival of humans, they remain a part of the body's physiological makeup because of the role they play in protecting the eyes from dirt, sweat, and rain, as well as communication. People have developed other means, such as hats, umbrellas, and goggles to serve the purpose of eyebrows more effectively, but the presence of eyebrows may suggest that they were once important to earlier species' survival.

The eyelashes grow at the edges of the eyelid and protect the eye from any dirt that may enter the eye. Eyelashes are to humans what whiskersare to cats; they are used to sense when dirt, dust, or any other potentially harmful object is too close to the eye. The eye reflexively closes as a result of this sensation.