A shaved chimpanzee skin#

Some of the most ancient figurines do have coiffed hair. This might explain why lank, unkempt locks are the mark of the social pariah. If this is correct, then the main function of head hair is to be cut and styled for maximum impact.

Grooming is time-consuming, and so having well-groomed hair shows you are resourceful and have good social contacts. Indeed, precisely because our head hair needs so much care, it makes a perfect hoarding upon which to advertise social and sexual status. Most people find a strong, healthy head of hair attractive. Sexual selection could also explain our head hair.

A shaved chimpanzee skin#

Hair-free skin may have been a billboard to advertise good health and hence attract mates – a sexual come-on saying, “Look how unblemished and parasite-free I am.”

For whatever reason, the least hairy of our ancestors were considered the most attractive and so produced more offspring. There’s also sexual selection, which was Charles Darwin‘s preferred explanation. We may also have lost body hair to improve our ability to identify others and to make communication easier, or to resist disease, since fur is a prime habitat for parasites. Look! No parasitesīut it is not the only possibility. Around this time our ancestor Homo erectus was living on the baking savannah, which supports the thermoregulation hypothesis. Genetic evidence suggests that we became furless around 1.7 million years ago. Head hair, meanwhile, became thicker and more luxuriant, protecting our ancestors’ brains from the midday sun, and also retaining heat in the cold. Hair loss was also presumably aided by technological innovations such as clothes, fire and cave-dwelling, which lessened the importance of fur for keeping warm at night. Body hair receded, removing an unnecessary insulating layer and also allowing the skin to be cooled by sweating. The leading one is that when our bipedal ancestors moved out of the forests and onto the searing heat of the savannah, they needed to keep their bodies cool while also sheltering their big brains from the sun. Ideas abound as to why evolution has endowed us with such a unique combination of hair types. That means head hair can theoretically grow to almost a metre in length. Armpit hairs make it to six months, but head hairs grow non-stop for six years or more. Leg hairs grow for about two months, which is why they are short and fine. The length of the growth phase is controlled by hormones. The hair falls out and the follicle goes dormant for around six months before sprouting new hair-producing cells and entering a new growth phase. But at some point the hair-producing cells die off and growth stops. During the growth phase the hair grows continuously at about 0.4 millimetres per day, getting longer and thicker in the process. Hair follicles go through cycles of growth and dormancy. This is what determines their length and thickness. Beyond that, the main difference between hair types is how long they grow for before the follicle runs out of steam. Human hair comes in two basic types: terminal hair, which grows on the scalp, eyebrows and eyelashes, and vellus hair, which is found everywhere else.

No wonder our relationship with our hair is a tangled one. We are pretty much the only animal to have hair that grows continuously for many years, and also to suffer the indignity of going bald. Our head hair is almost uniquely long and flamboyant. Most of our body hair is so wispy and short as to be almost invisible, though in some places it is coarse and curly. All told you have about 5 million follicles, about the same as chimps and other primates.īut the similarities stop there. But in fact your entire body (with the exception of the palms of your hands and the soles of your feet) is covered in hair. You may not think you are, and compared with, say, a chimpanzee, you appear distinctly bald.