Why do people have hair on the body?

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Maintenance of body hair can be quite uncomfortable, especially in summer, considering that you must devote time to this process. When adding up the time spent by men to remove facial hair throughout life, we achieve a period of one month, while women spend hundreds of hours in order to meticulously remove hundreds of unwanted hairs on the body.

Is only visible hair on the skin surface, but the real action takes place in the skin. Cells inside the hair follicle divide and multiply, fill the spaces inside the follicle and old cells are pushed outward. Then the old cells harden and leave the follicle, forming hair.


1. Overview
2. Composition and phases of hair growth
3. Why do people have hair?
4. Body hair function

Composition and phases of hair growth

The hair is mostly composed of dead tissue and a protein called keratin. Hair does not grow continuously but, each hair goes through active and resting phases.

The process of cell division occurs when the hair grows in length and is called the active phase or anagen. Anagen phase persists for a while, depending on your hair type, then rests slowly, or telogen phase.

Since hair is composed of dead matter, it falls during the telogen phase. Anagen phase of hair on the body lasts only a few months while in the case of hair on the scalp, phase lasts several years.

Differences in growth phase, size and density of the hair follicle varies depending on where the person grew up, but also from person to person.

In the womb, fetuses are covered with tiny wires called lanugo hair. Shortly after birth, on the baby’s body are growing thin threads called vellus, which is non-pigmented hair. At puberty, vellus hairs will be replaced by some coarse hairs called terminal (eg armpits and genital area).

Why do people have hair?

Certainly, humans are mammals with the least hair on the body. Only a few mammals, including elephants and rhinos, have rarely hair like humans. In this case, you must take into account a simple explanation for the low amount of hair: rhinos and elephants spend so much time immersed in water to maintain low body temperature.

People have the same amount of hair follicles on the body like other primates. Even though there are similarities between a human and a chimpanzee on hairless parts of the body, the hair on human copra is much finer and shorter than the chimpanzee. Yet why, during human evolution were lost thick layers of hair?

At one point it looks like thick hair had become more of a burden than a help. One of the scientific theories say that primitive man lived rather in the water and his thin and rare hair was a way to adapt to the environment.

Another explanation is that thinning hair was a way to prevent the spread of adaptation parasites that multiply in thick fur. Other landmarks are based on the fact that humans have become biped about two million years ago.

Standing up in two legs instead of fours, people third of the body exposed to sunlight. In this position it would not be necessary to total cover of the body with fur, for sun protection.

No matter which of these evolutionary factors was the trigger, all these ways of adaptation was that which led models of human body hair. On some areas like head, armpits and genitals, hair grows thicker and often, while in other places, such as the beck the hair is rarely seen and is quite thin (generally).

Body hair function

Imagine wearing a hoodie during sunny days of July. Your body warms quickly in this manner, you will feel uncomfortable and you start to sweat. After 30 minutes you simply boil and you feel the need to be naked and do a cold shower. If people often had hair that chimps probably would have felt like wearing a hoodie, permanently especially when the air temperature rises.

Mammals have an internal mechanism called thermoregulation that allows the brain to regulate the temperature inside the bodies, but there are limitations in humans and the sensitivity increases as the temperatures are higher. To avoid overheating, perspiration starts, but for the sweat to act and cool the body, it must be kept by hair.

Most adults have about 5 million hairs all over their body. This is a pretty impressive number, but the structure of the hair (short and thin) it facilitates the body’s response through perspiration cools.

People have kept their hair for its protective role. This makes sense, because the head is one of the main parts of the body that is constantly exposed to the sun, including a large amount of heat and radiation.

On the other hand, men had a role in the mating process, which has led women to want to be attractive by removing hair from the body. Speaking of breeding, body hair may play a role in sexual attraction. Preferences differ, some people prefer partners with long, short or curly hair. Biological, areas with thicker hair (armpits and genitals) are closely associated with sexual selection. Both areas release their scent due to apocrine glands action.

Chemicals they emit scent glands that are unique to each person and can help attract the opposite sex partners – just like the action of pheromones in animals. Hair found in these areas amplifies the smell.



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