Answer by Diane Eager
First, a brief overview of human hair.
The sparse short hair on our bodies and limbs is often used as evidence for evolution by claiming human body hair is vestigial, i.e. a useless leftover from when we were hairy apes. However, human hair is not useless. To understand this we must remember there is more to a hair than just the part that projects beyond the skin surface. A hair is actually formed just under the skin in the hair follicle, or “hair root”. As well as containing the cells that make the hair shaft, it also has an oil gland. The secretions from the oil gland are important in keeping the skin lubricated and water resistant. Hair also has a function in maintain the body temperature i.e. thermoregulation. Even fine fuzz, called vellus hairs, helps maintain a layer of insulating warm air, or when the body is overheating fine hairs can help spread sweat over the body surface where it can evaporate faster and cool you down. Hair also enhances our sense of touch, as each follicles has a nerve fibre around the base which is stimulated when the hair is moved, detecting anything from very gentle air movement when an unseen being moves into the same room as you, right up to advance notice of someone’s attempt to touch you.
Hair follicles go through cycles of growth and regression. During the growth phase the follicle produces the hair shaft, and the longer the follicle remains in this phase the longer the hair will grow. When the growth phase is over the hair stops growing, becomes detached from the follicle and falls out, and the follicle enters a period of dormancy. If the growth phase is very short, the follicle will only produce a vellus hair, a short, usually non-pigmented hair that only just projects above the skin surface. The longer, thicker hairs seen in what we call hairy skin are called terminal hairs.
Almost all human skin contains hair follicles. The most notable exceptions are the palms, soles, lips, and backs of the ears. The variation in hairiness between different regions of the body, and between males and females, is related to how long the follicles are active. Long head and beard hair result from the follicles remaining in the active growth phase for a longer time. In humans this time us up to seven years with the longest growth of human head hair recorded in ‘reputable’ publications such as “The Guinness Book of Records” as being some 7m (20+feet). Apes head hair growth is measured in a maximum of a few centimetres so it is a significant difference.
The length of time spent in the growth phase is the result of a complex mix of hormonal and other growth factors, and how sensitive the hair follicles are to these.
The differences in hairiness between human individuals are due to differences in regulation of follicles, as are the changes in hairiness over an individual lifespan. A loss of control of follicle growth can result in an excess of hair. A classic example is Esau in the Bible, who is noted as being an unusually hairy man (Genesis 25:25, 27:11). Excessive hairiness is called hypertrichosis. At present the black skinned and Asian humans have the least hairy bodies while white skinned people usually have fairly hairy bodies. Yet all can grow very long head hair.
Changes in follicle activity over an individual’s lifespan can result in apparent hair loss in some places, and gain in others, and you have such interesting hair situations such as the increase in hair in the ears and nose with age, and Grandpa joking that he’s going bald because the hair on his head is slipping out his ears and nose. Male pattern baldness is not due to a loss of hair follicles, but to a degenerate change in their activity so that they only produce vellus hairs.
Now, let’s consider what hairy changes would have to happen if we wanted to evolve apes into humans. According to evolution, apes with all-over dense short hair somehow changed into human beings with long head and beard hair, but sparse short body hair. This could conceivably happen by altering the way hair follicles respond to stimulation by hormones and growth factors, but it does not make any sense if evolution claims to be driven by the struggle for existence and survival of the fittest. Head hair that is only a few inches long is enough to protect the head from the sun, and provide thermal insulation. You don’t need long hair for that reason. Long flowing hair from head or beard would be a nuisance, if not a definite hazard, for any ape-like creature scraping up a living by hunting and fighting. Furthermore, if ape-men evolved whilst living on an African savannah under the hot sun, losing thick hair on the body and limbs would leave them exposed to sunburn and skin cancer. This would not make such creatures fitter in an evolutionary world.
The difference between hair growth and hair patterns in apes and people only makes real sense if humans were created separately from animals, and our hair was not given just for physical protection, but also for aesthetic reasons. Our eyes and minds are created to perceive things that are visually attractive, and we have mouth and mind that can then declare “Oh Lord that’s really attractive! Thank you.”
For more on structures that are considered to be evolutionary vestiges download PDF article Vestigial Organs here
Were you helped by this answer? If so, consider making a donation so we can keep adding more answers.
For USA tax deductible donations click here.
For UK tax deductible donations click here.
For Australia and rest of world click here.