why do people have so much hair in thier armpits?

Question

what is the evolutionary reason, that people have lost most of thier hair....except in a few key places (pubes, armpits, head)??

Answer 1

The armpits are known scientifically as the axilla, and armpit hair, axillary hair. The tissue in this area has a concentration of sebaceous glands, fatty glands at the base of the hair follicle which release the lipidous substance sebum, which functions as a hair/skin lubricant. Odour is caused by natural bacteria that feed on the excretion.
The armpits ( er, axilla...) seem to be to be a high-friction part of the body, epecially considering our upright, armswinging gait. Subum might give the hair a lubricated quality that prevents chafing and keeps the hair and skin pliant and healthy. There also seems to be quite a few lymph nodes close to the surface around the underarms, and the lymphatic system deals with similar fluids. So underarm hair might be leftover anti-frictional primate hair. Considering all that bacteria, it might be the last place you want an dermal infection. And all that pheromone/ sexual status stuff sounds good too. But what frictional forces to people experience in the groin area?

I can't think of any!

Answer 2

Our body has a self defence mechanism and due to this hair is grown in all places where it feels that it secure the places from any hits etc and hence hair is grown on head where our brain is situated and in pubic places where our tender organs are situated and in armpits as a shock absorber Previously before civilzation humans also used to have whole body full of hair for the same reason of protection but as we started to wear clothes and proctect ourselves the hair during the course of time stopped growing. Similarly when people wear helmets regularly we see that they lose the hair on the head . Thats all.

Answer 3

Ecolink's got the right answer. As much as we are disgusted by the smell now, for our ancestors, arm pit scent acted as pheromones. Having hair there just increases the surface area.

Eyebrows evolved for communication--we can read each others expressions better. We are very social animals, afterall.

Pubic hair is one of secondary sexual characteristics. Our ancestors used it as visual cues for determining who is sexually mature.

Hair on head? Actually I don't really know. We lose a lot of heat from our heads, so it could be to prevent the loss of heat, but people that evolved in colder climates (Caucasians) seem to have thinner hair than people who evolved in warmer climates (asians and africans) so there goes my hypothesis...

Answer 4

Hair protects the skin from damage
like rubbing.
(your arms and legs scraping skin from your body would be painful).

Hair provides insulation from the cold.
Wearing clothing over many tens of thousands of years has reduced this need. Excess hair Under our clothing makes us sweat more, adds body heat, reduces body fluids; all things that are a disadvantage.

Hair on the head has been less impacted by clothing. The brain uses a dispropotionate amount of blood when compared to comparable-sized body areas. But our heating/cooling system uses the skin as a radiator. Other body areas are less dense and cool more quickly than the head; but it has more blood flow so the head area often continues to radiate heat via sweat to continue the cooling process for the deeper regions of the body to complete cooling. -Hair on the head insulates the head itself from excessive cooling.

Answer 5

We lost most of our hair when we started walking upright. The hair on our backs and stomacs was mostly to protect our skin from the sun, but when we started walking upright, only a small part of our body was receiving a lot of direct sunlight, and that place (your head for the slow ones) still has thick hair.

Other patches of hair has its own reasons. The one i didnt see answered was pubic hair, which is to show sexual maturity.

Answer 6

We're still animals and we react subconsciously to smells. Armpit hair helps disseminate each person's aroma.

Answer 7

We have hair in our armpits to prevent sweat from dripping down our bodies. (of course deodorant was invented to prevent now) Same with eyebrows, to keep sweat out of our eyes.

Answer 8

Acutally God made us this way. In microevolution I belive that Hair has become aesthetically ugly so people don't mate with hair people. Still, God gave us razors so we use em.

Answer 9

some of us are closer to the monkies than others
i have very little