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  • Ah, hair.

  • Who doesn't love it?

  • We style our hair, use it to express ourselves, and do our best to keep it healthy so we can

  • show it off.

  • That is, unless it's there.

  • Or there.

  • Or especially there.

  • Yes, there's one type of hair that most people could do without - body hair.

  • Whether it's back and chest hair, underarm hair, or the hair that lurks beneath your

  • underpants, this hair can be an unwelcome sight for many people - and it's hard to

  • get rid of, especially permanently.

  • People subject themselves to different treatments to try to get rid of body hair, including

  • shaving - with all the nicks that come with it - to using foul-smelling hair removal cream.

  • Then there's those painful waxing sessions to get rid of large strips of hair, and we

  • can't forget plucking those stray hairs out with tweezers and trying not to pinch

  • your skin.

  • Alternatively, you could just go au naturel - even though some particularly hairy people

  • would probably rather not hearMommy, there's a Bigfoot on the beach”!

  • The question is, why?

  • Why do we still have body hair and what purpose does it serve?

  • And why are people so determined to get rid of it?

  • We're obviously not the only mammals to have hair all over our body, as anyone who's

  • whiled away hours petting a cat can tell you.

  • And when we get closer to our relatives - primates - we see the same thing.

  • Most have fur covering their entire body, although the length, color, and thickness

  • of the hair varies.

  • But their hair is more uniform and covers them mostly evenly, which is not the case

  • for human hair.

  • So what sets human hair apart?

  • Human hair is divided into two distinct types, and we're the only species to have this

  • unique hair pattern.

  • The hair you know and love is called Terminal hair, and it grows on the scalp, eyebrows,

  • and eyelashes - along with on the feet and chest and other areas.

  • This hair is thick, unusually long for hair, and grows on the scalp continuously.

  • Other large apes have terminal hair as well, but small apes and monkeys do not - hence

  • their thinner, sleeker fur coat.

  • The other type of hair, you might not even be aware of.

  • Vellus hair is the earliest form of body hair.

  • It's extremely thin, light-colored, and wispy - growing all over the body except a

  • few areas of skin like the lips, palms, soles, and some areas of the genitals.

  • It has a purpose - helping to insulate the body during the winter and keep it cool in

  • the summer by wicking away sweat.

  • It's almost invisible unless you're looking for it, so it's very rare for people to

  • shave it - especially as it's most common during childhood.

  • So what changes in this light, invisible hair?

  • In a word, puberty.

  • This hormone change causes the immature vellus hair to be replaced with terminal hair, making

  • the previously invisible body hair suddenly very visible.

  • While women will develop some additional body hair, usually in the legs and armpit areas,

  • it's men who get the brunt of this transformation.

  • Most women's body hair will maintain the quality of vellus hair, but men can expect

  • to develop thicker facial hair as well as hair all over their body.

  • This is called androgenic hair, and while it rarely grows to the same length as the

  • terminal hair on the scalp due to a shorter active period and a longer dormant period,

  • it can still grow to several inches long.

  • Hence, why getting rid of body hair became a major industry.

  • The question is why we have this hair at all.

  • The answer, as with most things, is a story of evolution.

  • Our current status as the dominant species of Earth wasn't always the case, and in

  • past times we had a lot more to fear from the world around us.

  • Our body hair served as a protective barrier, allowing our body to perceive movement and

  • vibration in our hair before something reached our skin.

  • This is particularly useful when making our way through close quarters - say, near bushes

  • with thorns on them.

  • When our hairs get brushed, we know to give the area a wider berth so our skin doesn't

  • get harmed.

  • This is similar to the function of whiskers on cats, as they use them to sense if they

  • can squeeze into a tight space.

  • If their whiskers clear the opening, they know they won't get stuck.

  • But what's the function of body hair on other areas of the body?

  • One of the areas that becomes hairy during puberty is the underarms, and it's also

  • one of the areas that people work the hardest to keep hair-free.

  • The location of this hair, which is usually among the longest on the body aside from the

  • scalp, is a puzzle to scientists.

  • After all, the underarm is usually kept protected by being folded under the shoulder.

  • It's a hidden area that won't usually come into common with too many exterior dangers.

  • That is, at least any dangers that we can see.

  • One theory about why we have armpit hair is that it's for protection from sweat.

  • The hair naturally wicks sweat away from the underarm and keeps it from becoming a breeding

  • ground for bacteria in the moist area.

  • This can prevent irritation and infection, especially among those who work out or do

  • manual labor and are producing more sweat than usual.

  • This is contrasted to the common fungal infections that happen around the feet like Athlete's

  • Foot.

  • There's usually no hair between the toes and they're usually covered in socks and

  • shoes with no way for moisture to escape, so the moisture, bacteria, and fungal spores

  • get trapped.

  • But microscopic infections aren't the only danger to the skin.

  • In the past, when most people were hunter-gatherers, they spent a lot of time in contact with nature.

  • That led to a lot of dangers - like being mauled by a stray tiger - but many of the

  • threats were smaller.

  • Parasitic insects like ticks and mosquitos could cause infections and carry diseases,

  • which could be fatal without modern medicine.

  • Even today, malaria is one of the deadliest contagious diseases in the world.

  • A thick coating of body hair could make it harder for insects to penetrate to the skin,

  • and make it easier for humans to detect them early and get rid of them before they cause

  • damage.

  • The trade-off is that some parasites flourish in hair, like lice - as any parent who has

  • gotten a note about a head lice outbreak knows.

  • With all the things out there, the question might be - why don't we have more body hair?

  • While some humans are naturally hairy, even the hairiest person isn't going to have

  • the thick coat of fur that we'll see on a gorilla.

  • That is, except those suffering from Hirsutism, a condition caused by an endocrine imbalance

  • that causes excessive hair growth.

  • This can cause a male pattern of hair growth on women, including significant facial hair.

  • In more extreme cases, it can create a full-body hair growth more akin to those seen in other

  • mammals.

  • Those with extreme cases of Hirsutism in the past often found themselves isolated or working

  • in circus freakshows with such insulting names asBearded LadyorWolf Boy”.

  • But the average person is far less hairy than our mammalian cousins.

  • So when in evolution did this change?

  • Scientists believe the shift from a traditional full-body fur coat came at least two million

  • years ago, but possibly over three million.

  • One of the clues they look at is when two species of lice diverged.

  • Pubic lice, which were more common preying on animals with full fur coats, and head lice,

  • which are more specifically geared towards targeting the thick coat of hair we have on

  • our heads.

  • They also believe that this shift happened when humans became more evolved at protecting

  • ourselves from the elements.

  • One of the biggest advantages of a fur coat is the warming effect in the winter.

  • But at a certain point, we evolved so that protection from the cold was less important

  • than a more manageable amount of body hair and fewer hair parasites.

  • So are all humans equally hairy?

  • That would be a clear no.

  • Studies across populations indicate that some populations have much more body hair than

  • others.

  • Indo-Europeans, Spaniards, and Semites are the most hairy, while Native Americans, East

  • Asians, and Australian Aborigines have almost no body hair.

  • While the reason for this isn't clear, most scientists believe that it's a quirk related

  • to the evolution of hair follicles to be sensitive to enzymes generated during puberty.

  • So is body hair just a quirk of evolution, or does it still serve a purpose today?

  • Before modern man, wearing clothing was rare.

  • Early man was either naked, or wearing only a thin piece of protective cloth like a loincloth

  • to guard sensitive areas.

  • Now, we're usually clothed over the majority of our body for the entire day - except for

  • nudists.

  • So the need for body hair as protection isn't there anymore, since we add our own.

  • But body hair still serves its other purpose - moisture reduction.

  • Wearing clothes can trap the moisture on the skin, especially if you're wearing tight

  • clothes during an intense workday or at the gym.

  • That could result in irritation or infection - but body hair can reduce that risk by wicking

  • the moisture away and keeping it from concentrating on the skin.

  • That's why most doctors will recommend boxers over briefs, to let the skin breathe and the

  • hair do its work.

  • So if hair has an evolutionary purpose, why do many people eventually lose it?

  • You may remember it from watching your dad comb his hair and pull away a few more hairs

  • every day, but many men eventually lose the hair on their heads.

  • This is called balding, and is usually a sign of aging caused by a combination of genetics

  • and natural male hormones.

  • It can happen to women as well, although it's usually less severe, and can be triggered

  • by physical or mental stress.

  • Some level of hair loss is common in women following pregnancy.

  • While it can sometimes taper off, male-pattern baldness is usually progressive - and permanent,

  • leaving millions of men to go hat-shopping.

  • Another kind of hair loss, though, is more severe.

  • Alopecia areata is an autoimmune disorder that can cause sudden hair loss.

  • This can happen in one spot when the hair follicles go dormant, but it can also spread

  • over the entire scalp resulting in complete baldness - or even over the entire body, resulting

  • in the loss of every single hair down to the smallest vellus hair.

  • What causes this sudden effect isn't clear, but it's speculated that the body's immune

  • system perceives hair as a foreign object and ejects it from the hair follicle.

  • This condition is usually permanent but some efforts to slow its process or reverse the

  • effects with immunotherapy and steroids have shown some success.

  • Awareness of alopecia has become more widespread thanks to public statements by famous people

  • including Congresswoman Ayanna Pressley and athlete Kevin Bull.

  • So it seems like we're all just stuck with whatever amount of hair our genetics want

  • us to have, right?

  • This is mostly true, but hair removal and prevention has become a massive industry.

  • Temporary removal methods like waxing, shaving, and plucking are common, but the hair will

  • usually grow back quickly.

  • That's why people who want to remove unwanted hair permanently, especially stray ones on

  • the face or other visible areas, are turning to high-tech methods.

  • While depilation, or removing the hair above the skin, is only a temporary measure, epilation

  • can have more permanent results.

  • This is the removal of the entire hair including the part below the skin, and the most popular

  • measure is electrology.

  • This uses a thin probe in the hair follicle to destroy the germ cells needed for hair

  • growth.

  • But are there ways to reduce hair growth permanently beyond targeting specific hairs?

  • Laser hair removal uses an intense beam of light to target hair and destroy the hair

  • follicle.

  • While at first it'll grow back, several sessions can permanently destroy the follicle.

  • The length it'll take to do this will vary based on how thick and dark the hair is, and

  • there's enough interest in the method that many hair care manufacturers have created

  • at-home kits for laser hair removal.

  • The problem is, the type of lasers that are safe to use at home are weaker than the ones

  • used by professionals, so results using at-home kits will vary.

  • While nothing will happen from removing a few pesky hairs, it seems like evolution knows

  • what it's doing.

  • We haven't lost our body hair because it still has a purpose - helping us regulate

  • moisture and temperature and protecting our skin, even if it's not always ideal for

  • beach season.

  • For more on the genetic quirks of hair, check outWhy Do We Have Different Skin, Hair,

  • and Eye Color?”, or check outThings That Happen to your Body When You're Asleep

  • for more on the complex way your body operates.

Ah, hair.

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