One of the most fascinating things about hair is that we don’t have very much of it. That’s because most of our body has evolved to be mostly naked in order to help us keep cool. The evolution of more naked skin occurred at the same time as the evolution of a higher density of sweat glands. Sweat is really important for keeping us cool, especially when we’re exercising in hot places.

So much about why we have the hair we do is about regulating our body temperature. New research is showing that tightly curled hair helps to insulate our heads from intense heat from the sun. This is especially important in regions near the equator where the sun is strong year round. We are going to learn much more about this in the coming years.

Hair on our faces has special meaning because faces convey so much information about our emotions and intentions. Eyebrows help to magnify the movement of the muscles around our eyes and help us communicate feelings of concern, anger, or disgust. This is really important today, and may have been even more important to us in the past:

There are lots of different theories about why men have facial hair. We know facial hair starts showing up later in puberty and that it’s related to increased testosterone production. But the reasons why some men have thicker hair than others are the subject of much speculation.

Even though we don’t have much hair on most of our bodies, the hair we have left is really important. The fine vellus hairs on our body help us to perceive gentle touch that makes us feel secure and comforted. Gentle, social touch is important for all of our primate relatives, especially during grooming behavior.

Next Section »