It reduces friction Armpit hair prevents skin-to-skin contact when doing certain activities, such as running and walking. The same thing happens with pubic hair, as it reduces friction during sex and other activities.
Armpit Hair Protects Your Skin
In the case of your underarms, it helps reduce skin-on-skin friction when you swing your arms as you walk or run. Armpit hair can save you from unnecessary chafing, irritation, or even heat rash, which can happen when sweat and abrasion mix.
While there are no true health benefits to shaving the arms, some people prefer the look and feel of hair-free arms and others find that having hairless armpits minimizes body odor associated with armpit sweat.
According to a study published in Behavioral Ecology and Sociobiology, not shaving your armpits has little to no effect on body odor. As long as you're still regularly showering and using deodorant you should expect to smell the same as you always do.
Culturally, the Chinese consider it bad luck to alter their physical appearance in any way. Women in the U.S. have been on quite a roller coaster ride when it comes to their armpit hair, or lack thereof, over the past century.
The main role of pubic hair is to reduce friction during sex and other forms of exercise, protecting the delicate skin around the genital area. Just like eyelashes and nose hair, pubic hair helps prevent the transmission of bacteria, trapping any dirt, debris, and microorganisms that could be harmful to the body.
Development and growth
Although vellus hair is already present in the area in childhood, chest hair is the terminal hair that develops as an effect of rising levels of androgens (primarily testosterone and its derivatives) due to puberty. Different from the head hair, it is therefore a secondary sexual characteristic.
Leg hair and arm hair developed to help prevent chafing so we could move around without causing friction.
Many theorize that its purpose is similar to hair on other parts of the body that regulate body temperature. As sweat is produced from the sweat glands, hair provides more surface on which it can evaporate faster. In cooler climates, it can also serve as a form of insulation that allows you to trap more body heat.
In the 1920s, the new fashion for sleeveless tops and short dresses meant that the legs and armpits of American women were now visible in social situations, and advertisers seized the opportunity to encourage women to shave their legs and their armpits.
As bipeds, or animals that walk upright on two legs, our heads are directly exposed to the sun. Near the equator, where humans evolved, sun exposure can be overbearing, and head hair helps people avoid overheating. "It's sort of a built-in hat," Pagel said.
In response to rising levels of androgens (mainly testosterone) during and after puberty, the skin of the abdomen begins to produce coarser, longer and more pigmented hair (terminal hair).
Hormones called androgens, which are present in both sexes, stimulate body hair (known as vellus hair) to darken and coarsen. Men have higher levels of androgens than women, so their body hair tends to be more prolific.
Men all have roughly the same amount of testosterone. Certain genes make your hair follicles more or less sensitive to the amount of testosterone in your body. Basically, an enzyme converts testosterone into a substance that shrinks hair follicles.
Bacteria can cling to hair. In the vaginal area, that is both a good thing and a bad thing. You need your good vaginal bacteria to prevent an overgrowth of yeast, but when bacteria mix with the sweat and oil on your pubic hair, it can produce a smell.
Removing pubic hair may therefore make a person more susceptible to common infections, such as UTIs, vaginitis, and yeast infections. Hair removal can also irritate your skin, leading to skin infections such as cellulitis and folliculitis. In other cases, grooming-related injuries, such as cuts, could become infected.
When the hair wicks sweat off the skin (to keep you dry and cool), it collects, along with pheromones and bacteria, in that area. "The hair traps the smell," Michael Cackovic, M.D., an ob/gyn at Ohio State Wexner Medical Center, tells SELF.
Men report grooming their pubic hair for various reasons including sex and hygiene, comfort, and curiosity. Reasons for pubic hair grooming by age are reported in Figure 1. The majority of men report grooming in preparation for sexual activity with a peak prevalence of 73% among men aged 25 to 34 years.
If you take attractiveness out of the equation, there are a few reasons to trim or shave your chest hair for your own sake: to lend extra definition to your muscles, streamline your body for swimming, to keep it from poking out of your shirt. All good reasons.
As we age, our prolonged exposure to testosterone starts to play a visible role on other body hair as well. Just like it transforms the vellus hair on a young man's face into a thick beard, it also changes the nearly invisible hair that grows in places like our ears into thicker strands.
Like other parts of the body, the skin of the areola contains hair follicles. These can be affected by the fluctuations in hormones during times of significant hormonal change, such as puberty, pregnancy, and menopause.
It's possible — and normal — to have hair almost anywhere on the body, so a few hairs on your nipples are nothing to worry about. Lots of girls have them.
There's no medical or hygienic reason for removing some or all of your pubic hair. But the removal process can be painful and cause many side effects, including: Genital itching, sometimes severe. Genital burns from waxing.
Many hair follicles stop producing new hairs. Men may start showing signs of baldness by the time they are 30 years old. Many men are nearly bald by age 60.
Stephen Wooding, calculate that the last sweep probably occurred 1.2 million years ago, when the human population consisted of a mere 14,000 breeding individuals. In other words, humans have been hairless at least since this time, and maybe for much longer.