why do we have hair under our arms?
395903
My guess, and it's only a guess is that it traps our own unique scent, which then attracts "mates."  Obviously, we only grow hair under our arms at puberty, and what occurs at puberty is that our sex organs develop, so that's the rationale behind my answer.  However, I do not know the biological reason why humans have relatively long hair in their armpits!
800782
That's because they choose to shave their hair, not because they are natural bald. A bald head is much easier to manage than something like an Afro.For example thick, curly hair that they have do dry as quickly after washing.
166144
Well, they are there for a few reasons.  Way back in caveman days, men and women were supposed to be attracted to each others BO...yuck. And more hair there, meant more BO.  Also, pubic hair is there so there will be less friction caused by sex and things like legs rubbing together, etc.  Now, we really don't need underarm hair, but shaving pubic hair is just a matter of choice. It still does help decrease friction.
146537
We were not born with clothes nor were we designed to wear them. The basic function of all body hair is warmth.
743630
Actually, your hair keeps growing throughout your life (excluding the upper scalp hair on some men). It's just that the hair folicles each have a programed length to which the hair shaft will grow. When the shaft reaches that length, it falls out and a new one starts to grow. Obviously, for some folicles, this programed length is longer than it is for others. That is why body hair is usually shorter than head hair. This is also why it is silly for a man to start worrying about going bald just because he sees some hairs in his brush. We are all constantly shedding hairs that have reached their maximum length. So, seeing a few hairs come off is normal. You only need to worry about it if you see an actual thinning of the hair.
638899
Your sweat actually contains urine, that's why it smells.  Since your armpits are a perfect place for heat and wetness, it is more abundant. Bacteria also feed off the sweat and emmit more stinky smells!
1167090
No. Because its perfectly normal  for a teen boy to have under arm hair. If your embarrassed about it just trim it down and it will look just fine. Besides if anyone else has any problem with it, Than their the ones that have issues, not you.
720536
hair actually covers all the body surface, except for palm of hands, sole of feet, eyes, lip/mouth, and nails.  Some of hairs on our body may be very small or thin for us to realize.
359348
One difference we have in comparison with a lot of other mammals is that we have a lot of sweat glands in our skin. They help to prevent our bodies from overheating, especially during exercise. As sweat cooling your body works best if the air on your skin can move easily (and especially if a breeze of air is blowing) I would guess that fur/hair would decrease the efficiency of this cooling system a lot. As humans are supposed to have evolved in warm areas of Afrika, protection from cold was not an issue for keeping hair. And protection from sunburn - as a upright walking species we kept our hair on the place where sunburn would be most of a problem. \nThat's my guess, so that may not be true, but I read not too long ago that sweating allows humans to exercise much longer without overheating than a lot of animals (and so hunt an animal to its heat exhaustion, despite if may be able to run faster), if you look up these studies you may find more.\nPS. I found at least one source for that theory, I added it below
380304
black underarms are caused from excessive shaving...the root of the hair is trapped under the skin. Try waxing...or electrolysis.
375574
My guess is that it doesn't get the exposure to sunlight & fresh air that hair on other parts of your body does.  Just a guess.
58297
Well, armpits are a pain because razors NEVER conform to the shape of an armpit and the bikini line is very sensitive but the place that has been shaved on my body that is the worst??? My elbow.  When I went for surgery last year to have a broken arm fixed, they have to shave the little hairs on your arm.  So now I have the hairs on my elbow again but they are blacker.  Oy.
830044
Ha! What an interesting question. Hair is regulated by our hormones, when a "child" becomes an adult and enter's their sexual maturity they start producing various sex hormones which causes hair in places to grow (unfortunately). Hair has many purposes: warm, decreases friction (with sexual activity), traps pheromones (especially arm pit, male facial hair, and genital hair) which in turn attracts the opposite sex.  The female population (at least many females that I know) spend a lot of time and money attempting to rid ourselves of hair . . . guess another purpose is served . . . supporting the economy! LOL!
937258
It is believed that the functions of pubic hair include the dissemination of pheromones and protection from the friction of sexual intercourse. Natural selection may also have sustained it because it can show a potential sexual partner that the other person is sexually mature and can reproduce. Pubic hair and the growth between the tops of the legs and the buttocks, like under arm hair, helps to lubricate the areas, making movement smoother and more comfortable.\n\nThere is no definitive theory on the reason for the existence of pubic hair. The prevailing theory relates to pheromones — scents that the body produces that can be sexually stimulating to others. In this theory, the tufts of hair that grow around the genitals, as well as under the arms, capture these erotic scents. Pheromones get trapped in the pubic hair when apocrine glands release an odorless secretion on the surface of the skin that combines with bacteria decomposed by the secretions of the sebaceous glands. Humans have the same number of hair follicles as gorillas, chimpanzees and orangutans, but body hair is generally very fine or barely visible in comparison. So, while pubic hair and underarm hair might be considered the primary scent traps, they are not the only ones. For some people, scents from these areas are noticeable and consciously increase sexual arousal. Pheromones might not be obvious but may be detected subconsciously.\n\nAnother theory is that the pubic hair keeps the genitals warm. The purpose of women's pubic hair could be similar to that of the cilia in the nose, in that it prevents small foreign particles from entering the vagina. If this is true, male pubic hair may be a vestigial trait.
1106215
Just be happy you live at this point in human evolution and not tens of thousands of years ago, we used to be covered with hair head to toe.  As body hair became less necessary, we gradually evolved to the point where body hair is very light except for certain areas like the face, underarms and groin.  Eventually, it's possible that all body hair will be bred out of the species and mankind will be hairless.
666792
Nearly all the skin of the human body except palms of hands and soles of feet is covered with hairs. The density of the hairs (in hair follicles per square centimeter) thickness of the hairs, color of the hairs, speed of hair growth, and qualities such as kinkiness, vary from one part of the body to another, and from one person to another. All of these features have strong genetic determinants, as demonstrated by the heritability of these qualities.\n\nDoctors generally distinguish scalp hair, vellus hair, and androgenic (terminal) hair. \n\nVellus hair is the hair on the rest of the body which has not been stimulated and transformed by sex hormones. Androgenic hair is the hair that greatly increases in heaviness and rate of growth with puberty.
209647
Because it relaxes the hair and makes it easier for them to cut and comb it properly. Dry hair is also very itchy when it lands on their arms and your neck and face, and is harder to brush off. Also, it floats in the air more easily and you would both be breathing it. If you just wet the hair, it becomes sticky and hard to comb, so they wash and condition it.